aboutsummaryrefslogtreecommitdiff
path: root/src/net_processing.cpp
blob: 80655c61e7989d00d8d3738ab1a2c0d166303318 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2020 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <net_processing.h>

#include <addrman.h>
#include <banman.h>
#include <blockencodings.h>
#include <blockfilter.h>
#include <chainparams.h>
#include <consensus/validation.h>
#include <deploymentstatus.h>
#include <hash.h>
#include <index/blockfilterindex.h>
#include <merkleblock.h>
#include <netbase.h>
#include <netmessagemaker.h>
#include <node/blockstorage.h>
#include <policy/fees.h>
#include <policy/policy.h>
#include <primitives/block.h>
#include <primitives/transaction.h>
#include <random.h>
#include <reverse_iterator.h>
#include <scheduler.h>
#include <streams.h>
#include <sync.h>
#include <tinyformat.h>
#include <txmempool.h>
#include <txorphanage.h>
#include <txrequest.h>
#include <util/check.h> // For NDEBUG compile time check
#include <util/strencodings.h>
#include <util/system.h>
#include <util/trace.h>
#include <validation.h>

#include <algorithm>
#include <memory>
#include <optional>
#include <typeinfo>

/** How long to cache transactions in mapRelay for normal relay */
static constexpr auto RELAY_TX_CACHE_TIME = 15min;
/** How long a transaction has to be in the mempool before it can unconditionally be relayed (even when not in mapRelay). */
static constexpr auto UNCONDITIONAL_RELAY_DELAY = 2min;
/** Headers download timeout.
 *  Timeout = base + per_header * (expected number of headers) */
static constexpr auto HEADERS_DOWNLOAD_TIMEOUT_BASE = 15min;
static constexpr auto HEADERS_DOWNLOAD_TIMEOUT_PER_HEADER = 1ms;
/** Protect at least this many outbound peers from disconnection due to slow/
 * behind headers chain.
 */
static constexpr int32_t MAX_OUTBOUND_PEERS_TO_PROTECT_FROM_DISCONNECT = 4;
/** Timeout for (unprotected) outbound peers to sync to our chainwork, in seconds */
static constexpr int64_t CHAIN_SYNC_TIMEOUT = 20 * 60; // 20 minutes
/** How frequently to check for stale tips, in seconds */
static constexpr int64_t STALE_CHECK_INTERVAL = 10 * 60; // 10 minutes
/** How frequently to check for extra outbound peers and disconnect, in seconds */
static constexpr int64_t EXTRA_PEER_CHECK_INTERVAL = 45;
/** Minimum time an outbound-peer-eviction candidate must be connected for, in order to evict, in seconds */
static constexpr int64_t MINIMUM_CONNECT_TIME = 30;
/** SHA256("main address relay")[0:8] */
static constexpr uint64_t RANDOMIZER_ID_ADDRESS_RELAY = 0x3cac0035b5866b90ULL;
/// Age after which a stale block will no longer be served if requested as
/// protection against fingerprinting. Set to one month, denominated in seconds.
static constexpr int STALE_RELAY_AGE_LIMIT = 30 * 24 * 60 * 60;
/// Age after which a block is considered historical for purposes of rate
/// limiting block relay. Set to one week, denominated in seconds.
static constexpr int HISTORICAL_BLOCK_AGE = 7 * 24 * 60 * 60;
/** Time between pings automatically sent out for latency probing and keepalive */
static constexpr std::chrono::minutes PING_INTERVAL{2};
/** The maximum number of entries in a locator */
static const unsigned int MAX_LOCATOR_SZ = 101;
/** The maximum number of entries in an 'inv' protocol message */
static const unsigned int MAX_INV_SZ = 50000;
/** Maximum number of in-flight transaction requests from a peer. It is not a hard limit, but the threshold at which
 *  point the OVERLOADED_PEER_TX_DELAY kicks in. */
static constexpr int32_t MAX_PEER_TX_REQUEST_IN_FLIGHT = 100;
/** Maximum number of transactions to consider for requesting, per peer. It provides a reasonable DoS limit to
 *  per-peer memory usage spent on announcements, while covering peers continuously sending INVs at the maximum
 *  rate (by our own policy, see INVENTORY_BROADCAST_PER_SECOND) for several minutes, while not receiving
 *  the actual transaction (from any peer) in response to requests for them. */
static constexpr int32_t MAX_PEER_TX_ANNOUNCEMENTS = 5000;
/** How long to delay requesting transactions via txids, if we have wtxid-relaying peers */
static constexpr auto TXID_RELAY_DELAY = std::chrono::seconds{2};
/** How long to delay requesting transactions from non-preferred peers */
static constexpr auto NONPREF_PEER_TX_DELAY = std::chrono::seconds{2};
/** How long to delay requesting transactions from overloaded peers (see MAX_PEER_TX_REQUEST_IN_FLIGHT). */
static constexpr auto OVERLOADED_PEER_TX_DELAY = std::chrono::seconds{2};
/** How long to wait (in microseconds) before downloading a transaction from an additional peer */
static constexpr std::chrono::microseconds GETDATA_TX_INTERVAL{std::chrono::seconds{60}};
/** Limit to avoid sending big packets. Not used in processing incoming GETDATA for compatibility */
static const unsigned int MAX_GETDATA_SZ = 1000;
/** Number of blocks that can be requested at any given time from a single peer. */
static const int MAX_BLOCKS_IN_TRANSIT_PER_PEER = 16;
/** Time during which a peer must stall block download progress before being disconnected. */
static constexpr auto BLOCK_STALLING_TIMEOUT = 2s;
/** Number of headers sent in one getheaders result. We rely on the assumption that if a peer sends
 *  less than this number, we reached its tip. Changing this value is a protocol upgrade. */
static const unsigned int MAX_HEADERS_RESULTS = 2000;
/** Maximum depth of blocks we're willing to serve as compact blocks to peers
 *  when requested. For older blocks, a regular BLOCK response will be sent. */
static const int MAX_CMPCTBLOCK_DEPTH = 5;
/** Maximum depth of blocks we're willing to respond to GETBLOCKTXN requests for. */
static const int MAX_BLOCKTXN_DEPTH = 10;
/** Size of the "block download window": how far ahead of our current height do we fetch?
 *  Larger windows tolerate larger download speed differences between peer, but increase the potential
 *  degree of disordering of blocks on disk (which make reindexing and pruning harder). We'll probably
 *  want to make this a per-peer adaptive value at some point. */
static const unsigned int BLOCK_DOWNLOAD_WINDOW = 1024;
/** Block download timeout base, expressed in multiples of the block interval (i.e. 10 min) */
static constexpr double BLOCK_DOWNLOAD_TIMEOUT_BASE = 1;
/** Additional block download timeout per parallel downloading peer (i.e. 5 min) */
static constexpr double BLOCK_DOWNLOAD_TIMEOUT_PER_PEER = 0.5;
/** Maximum number of headers to announce when relaying blocks with headers message.*/
static const unsigned int MAX_BLOCKS_TO_ANNOUNCE = 8;
/** Maximum number of unconnecting headers announcements before DoS score */
static const int MAX_UNCONNECTING_HEADERS = 10;
/** Minimum blocks required to signal NODE_NETWORK_LIMITED */
static const unsigned int NODE_NETWORK_LIMITED_MIN_BLOCKS = 288;
/** Average delay between local address broadcasts */
static constexpr auto AVG_LOCAL_ADDRESS_BROADCAST_INTERVAL = 24h;
/** Average delay between peer address broadcasts */
static constexpr auto AVG_ADDRESS_BROADCAST_INTERVAL = 30s;
/** Average delay between trickled inventory transmissions for inbound peers.
 *  Blocks and peers with NetPermissionFlags::NoBan permission bypass this. */
static constexpr auto INBOUND_INVENTORY_BROADCAST_INTERVAL = 5s;
/** Average delay between trickled inventory transmissions for outbound peers.
 *  Use a smaller delay as there is less privacy concern for them.
 *  Blocks and peers with NetPermissionFlags::NoBan permission bypass this. */
static constexpr auto OUTBOUND_INVENTORY_BROADCAST_INTERVAL = 2s;
/** Maximum rate of inventory items to send per second.
 *  Limits the impact of low-fee transaction floods. */
static constexpr unsigned int INVENTORY_BROADCAST_PER_SECOND = 7;
/** Maximum number of inventory items to send per transmission. */
static constexpr unsigned int INVENTORY_BROADCAST_MAX = INVENTORY_BROADCAST_PER_SECOND * count_seconds(INBOUND_INVENTORY_BROADCAST_INTERVAL);
/** The number of most recently announced transactions a peer can request. */
static constexpr unsigned int INVENTORY_MAX_RECENT_RELAY = 3500;
/** Verify that INVENTORY_MAX_RECENT_RELAY is enough to cache everything typically
 *  relayed before unconditional relay from the mempool kicks in. This is only a
 *  lower bound, and it should be larger to account for higher inv rate to outbound
 *  peers, and random variations in the broadcast mechanism. */
static_assert(INVENTORY_MAX_RECENT_RELAY >= INVENTORY_BROADCAST_PER_SECOND * UNCONDITIONAL_RELAY_DELAY / std::chrono::seconds{1}, "INVENTORY_RELAY_MAX too low");
/** Average delay between feefilter broadcasts in seconds. */
static constexpr auto AVG_FEEFILTER_BROADCAST_INTERVAL = 10min;
/** Maximum feefilter broadcast delay after significant change. */
static constexpr auto MAX_FEEFILTER_CHANGE_DELAY = 5min;
/** Maximum number of compact filters that may be requested with one getcfilters. See BIP 157. */
static constexpr uint32_t MAX_GETCFILTERS_SIZE = 1000;
/** Maximum number of cf hashes that may be requested with one getcfheaders. See BIP 157. */
static constexpr uint32_t MAX_GETCFHEADERS_SIZE = 2000;
/** the maximum percentage of addresses from our addrman to return in response to a getaddr message. */
static constexpr size_t MAX_PCT_ADDR_TO_SEND = 23;
/** The maximum number of address records permitted in an ADDR message. */
static constexpr size_t MAX_ADDR_TO_SEND{1000};
/** The maximum rate of address records we're willing to process on average. Can be bypassed using
 *  the NetPermissionFlags::Addr permission. */
static constexpr double MAX_ADDR_RATE_PER_SECOND{0.1};
/** The soft limit of the address processing token bucket (the regular MAX_ADDR_RATE_PER_SECOND
 *  based increments won't go above this, but the MAX_ADDR_TO_SEND increment following GETADDR
 *  is exempt from this limit). */
static constexpr size_t MAX_ADDR_PROCESSING_TOKEN_BUCKET{MAX_ADDR_TO_SEND};

// Internal stuff
namespace {
/** Blocks that are in flight, and that are in the queue to be downloaded. */
struct QueuedBlock {
    /** BlockIndex. We must have this since we only request blocks when we've already validated the header. */
    const CBlockIndex* pindex;
    /** Optional, used for CMPCTBLOCK downloads */
    std::unique_ptr<PartiallyDownloadedBlock> partialBlock;
};

/**
 * Data structure for an individual peer. This struct is not protected by
 * cs_main since it does not contain validation-critical data.
 *
 * Memory is owned by shared pointers and this object is destructed when
 * the refcount drops to zero.
 *
 * Mutexes inside this struct must not be held when locking m_peer_mutex.
 *
 * TODO: move most members from CNodeState to this structure.
 * TODO: move remaining application-layer data members from CNode to this structure.
 */
struct Peer {
    /** Same id as the CNode object for this peer */
    const NodeId m_id{0};

    /** Protects misbehavior data members */
    Mutex m_misbehavior_mutex;
    /** Accumulated misbehavior score for this peer */
    int m_misbehavior_score GUARDED_BY(m_misbehavior_mutex){0};
    /** Whether this peer should be disconnected and marked as discouraged (unless it has NetPermissionFlags::NoBan permission). */
    bool m_should_discourage GUARDED_BY(m_misbehavior_mutex){false};

    /** Protects block inventory data members */
    Mutex m_block_inv_mutex;
    /** List of blocks that we'll announce via an `inv` message.
     * There is no final sorting before sending, as they are always sent
     * immediately and in the order requested. */
    std::vector<uint256> m_blocks_for_inv_relay GUARDED_BY(m_block_inv_mutex);
    /** Unfiltered list of blocks that we'd like to announce via a `headers`
     * message. If we can't announce via a `headers` message, we'll fall back to
     * announcing via `inv`. */
    std::vector<uint256> m_blocks_for_headers_relay GUARDED_BY(m_block_inv_mutex);
    /** The final block hash that we sent in an `inv` message to this peer.
     * When the peer requests this block, we send an `inv` message to trigger
     * the peer to request the next sequence of block hashes.
     * Most peers use headers-first syncing, which doesn't use this mechanism */
    uint256 m_continuation_block GUARDED_BY(m_block_inv_mutex) {};

    /** This peer's reported block height when we connected */
    std::atomic<int> m_starting_height{-1};

    /** The pong reply we're expecting, or 0 if no pong expected. */
    std::atomic<uint64_t> m_ping_nonce_sent{0};
    /** When the last ping was sent, or 0 if no ping was ever sent */
    std::atomic<std::chrono::microseconds> m_ping_start{0us};
    /** Whether a ping has been requested by the user */
    std::atomic<bool> m_ping_queued{false};

    /** A vector of addresses to send to the peer, limited to MAX_ADDR_TO_SEND. */
    std::vector<CAddress> m_addrs_to_send;
    /** Probabilistic filter to track recent addr messages relayed with this
     *  peer. Used to avoid relaying redundant addresses to this peer.
     *
     *  We initialize this filter for outbound peers (other than
     *  block-relay-only connections) or when an inbound peer sends us an
     *  address related message (ADDR, ADDRV2, GETADDR).
     *
     *  Presence of this filter must correlate with m_addr_relay_enabled.
     **/
    std::unique_ptr<CRollingBloomFilter> m_addr_known;
    /** Whether we are participating in address relay with this connection.
     *
     *  We set this bool to true for outbound peers (other than
     *  block-relay-only connections), or when an inbound peer sends us an
     *  address related message (ADDR, ADDRV2, GETADDR).
     *
     *  We use this bool to decide whether a peer is eligible for gossiping
     *  addr messages. This avoids relaying to peers that are unlikely to
     *  forward them, effectively blackholing self announcements. Reasons
     *  peers might support addr relay on the link include that they connected
     *  to us as a block-relay-only peer or they are a light client.
     *
     *  This field must correlate with whether m_addr_known has been
     *  initialized.*/
    std::atomic_bool m_addr_relay_enabled{false};
    /** Whether a getaddr request to this peer is outstanding. */
    bool m_getaddr_sent{false};
    /** Guards address sending timers. */
    mutable Mutex m_addr_send_times_mutex;
    /** Time point to send the next ADDR message to this peer. */
    std::chrono::microseconds m_next_addr_send GUARDED_BY(m_addr_send_times_mutex){0};
    /** Time point to possibly re-announce our local address to this peer. */
    std::chrono::microseconds m_next_local_addr_send GUARDED_BY(m_addr_send_times_mutex){0};
    /** Whether the peer has signaled support for receiving ADDRv2 (BIP155)
     *  messages, indicating a preference to receive ADDRv2 instead of ADDR ones. */
    std::atomic_bool m_wants_addrv2{false};
    /** Whether this peer has already sent us a getaddr message. */
    bool m_getaddr_recvd{false};
    /** Number of addresses that can be processed from this peer. Start at 1 to
     *  permit self-announcement. */
    double m_addr_token_bucket{1.0};
    /** When m_addr_token_bucket was last updated */
    std::chrono::microseconds m_addr_token_timestamp{GetTime<std::chrono::microseconds>()};
    /** Total number of addresses that were dropped due to rate limiting. */
    std::atomic<uint64_t> m_addr_rate_limited{0};
    /** Total number of addresses that were processed (excludes rate-limited ones). */
    std::atomic<uint64_t> m_addr_processed{0};

    /** Set of txids to reconsider once their parent transactions have been accepted **/
    std::set<uint256> m_orphan_work_set GUARDED_BY(g_cs_orphans);

    /** Protects m_getdata_requests **/
    Mutex m_getdata_requests_mutex;
    /** Work queue of items requested by this peer **/
    std::deque<CInv> m_getdata_requests GUARDED_BY(m_getdata_requests_mutex);

    explicit Peer(NodeId id)
        : m_id(id)
    {}
};

using PeerRef = std::shared_ptr<Peer>;

class PeerManagerImpl final : public PeerManager
{
public:
    PeerManagerImpl(const CChainParams& chainparams, CConnman& connman, CAddrMan& addrman,
                    BanMan* banman, ChainstateManager& chainman,
                    CTxMemPool& pool, bool ignore_incoming_txs);

    /** Overridden from CValidationInterface. */
    void BlockConnected(const std::shared_ptr<const CBlock>& pblock, const CBlockIndex* pindexConnected) override;
    void BlockDisconnected(const std::shared_ptr<const CBlock> &block, const CBlockIndex* pindex) override;
    void UpdatedBlockTip(const CBlockIndex *pindexNew, const CBlockIndex *pindexFork, bool fInitialDownload) override;
    void BlockChecked(const CBlock& block, const BlockValidationState& state) override;
    void NewPoWValidBlock(const CBlockIndex *pindex, const std::shared_ptr<const CBlock>& pblock) override;

    /** Implement NetEventsInterface */
    void InitializeNode(CNode* pnode) override;
    void FinalizeNode(const CNode& node) override;
    bool ProcessMessages(CNode* pfrom, std::atomic<bool>& interrupt) override;
    bool SendMessages(CNode* pto) override EXCLUSIVE_LOCKS_REQUIRED(pto->cs_sendProcessing);

    /** Implement PeerManager */
    void StartScheduledTasks(CScheduler& scheduler) override;
    void CheckForStaleTipAndEvictPeers() override;
    bool GetNodeStateStats(NodeId nodeid, CNodeStateStats& stats) const override;
    bool IgnoresIncomingTxs() override { return m_ignore_incoming_txs; }
    void SendPings() override;
    void RelayTransaction(const uint256& txid, const uint256& wtxid) override;
    void SetBestHeight(int height) override { m_best_height = height; };
    void Misbehaving(const NodeId pnode, const int howmuch, const std::string& message) override;
    void ProcessMessage(CNode& pfrom, const std::string& msg_type, CDataStream& vRecv,
                        const std::chrono::microseconds time_received, const std::atomic<bool>& interruptMsgProc) override;

private:
    void _RelayTransaction(const uint256& txid, const uint256& wtxid)
        EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /** Consider evicting an outbound peer based on the amount of time they've been behind our tip */
    void ConsiderEviction(CNode& pto, int64_t time_in_seconds) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /** If we have extra outbound peers, try to disconnect the one with the oldest block announcement */
    void EvictExtraOutboundPeers(int64_t time_in_seconds) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /** Retrieve unbroadcast transactions from the mempool and reattempt sending to peers */
    void ReattemptInitialBroadcast(CScheduler& scheduler);

    /** Get a shared pointer to the Peer object.
     *  May return an empty shared_ptr if the Peer object can't be found. */
    PeerRef GetPeerRef(NodeId id) const;

    /** Get a shared pointer to the Peer object and remove it from m_peer_map.
     *  May return an empty shared_ptr if the Peer object can't be found. */
    PeerRef RemovePeer(NodeId id);

    /**
     * Potentially mark a node discouraged based on the contents of a BlockValidationState object
     *
     * @param[in] via_compact_block this bool is passed in because net_processing should
     * punish peers differently depending on whether the data was provided in a compact
     * block message or not. If the compact block had a valid header, but contained invalid
     * txs, the peer should not be punished. See BIP 152.
     *
     * @return Returns true if the peer was punished (probably disconnected)
     */
    bool MaybePunishNodeForBlock(NodeId nodeid, const BlockValidationState& state,
                                 bool via_compact_block, const std::string& message = "");

    /**
     * Potentially disconnect and discourage a node based on the contents of a TxValidationState object
     *
     * @return Returns true if the peer was punished (probably disconnected)
     */
    bool MaybePunishNodeForTx(NodeId nodeid, const TxValidationState& state, const std::string& message = "");

    /** Maybe disconnect a peer and discourage future connections from its address.
     *
     * @param[in]   pnode     The node to check.
     * @param[in]   peer      The peer object to check.
     * @return                True if the peer was marked for disconnection in this function
     */
    bool MaybeDiscourageAndDisconnect(CNode& pnode, Peer& peer);

    void ProcessOrphanTx(std::set<uint256>& orphan_work_set) EXCLUSIVE_LOCKS_REQUIRED(cs_main, g_cs_orphans);
    /** Process a single headers message from a peer. */
    void ProcessHeadersMessage(CNode& pfrom, const Peer& peer,
                               const std::vector<CBlockHeader>& headers,
                               bool via_compact_block);

    void SendBlockTransactions(CNode& pfrom, const CBlock& block, const BlockTransactionsRequest& req);

    /** Register with TxRequestTracker that an INV has been received from a
     *  peer. The announcement parameters are decided in PeerManager and then
     *  passed to TxRequestTracker. */
    void AddTxAnnouncement(const CNode& node, const GenTxid& gtxid, std::chrono::microseconds current_time)
        EXCLUSIVE_LOCKS_REQUIRED(::cs_main);

    /** Send a version message to a peer */
    void PushNodeVersion(CNode& pnode, int64_t nTime);

    /** Send a ping message every PING_INTERVAL or if requested via RPC. May
     *  mark the peer to be disconnected if a ping has timed out.
     *  We use mockable time for ping timeouts, so setmocktime may cause pings
     *  to time out. */
    void MaybeSendPing(CNode& node_to, Peer& peer, std::chrono::microseconds now);

    /** Send `addr` messages on a regular schedule. */
    void MaybeSendAddr(CNode& node, Peer& peer, std::chrono::microseconds current_time);

    /** Relay (gossip) an address to a few randomly chosen nodes.
     *
     * @param[in] originator   The id of the peer that sent us the address. We don't want to relay it back.
     * @param[in] addr         Address to relay.
     * @param[in] fReachable   Whether the address' network is reachable. We relay unreachable
     *                         addresses less.
     */
    void RelayAddress(NodeId originator, const CAddress& addr, bool fReachable);

    /** Send `feefilter` message. */
    void MaybeSendFeefilter(CNode& node, std::chrono::microseconds current_time) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    const CChainParams& m_chainparams;
    CConnman& m_connman;
    CAddrMan& m_addrman;
    /** Pointer to this node's banman. May be nullptr - check existence before dereferencing. */
    BanMan* const m_banman;
    ChainstateManager& m_chainman;
    CTxMemPool& m_mempool;
    TxRequestTracker m_txrequest GUARDED_BY(::cs_main);

    /** The height of the best chain */
    std::atomic<int> m_best_height{-1};

    /** Next time to check for stale tip */
    int64_t m_stale_tip_check_time{0};

    /** Whether this node is running in blocks only mode */
    const bool m_ignore_incoming_txs;

    /** Whether we've completed initial sync yet, for determining when to turn
      * on extra block-relay-only peers. */
    bool m_initial_sync_finished{false};

    /** Protects m_peer_map. This mutex must not be locked while holding a lock
     *  on any of the mutexes inside a Peer object. */
    mutable Mutex m_peer_mutex;
    /**
     * Map of all Peer objects, keyed by peer id. This map is protected
     * by the m_peer_mutex. Once a shared pointer reference is
     * taken, the lock may be released. Individual fields are protected by
     * their own locks.
     */
    std::map<NodeId, PeerRef> m_peer_map GUARDED_BY(m_peer_mutex);

    /** Number of nodes with fSyncStarted. */
    int nSyncStarted GUARDED_BY(cs_main) = 0;

    /**
     * Sources of received blocks, saved to be able punish them when processing
     * happens afterwards.
     * Set mapBlockSource[hash].second to false if the node should not be
     * punished if the block is invalid.
     */
    std::map<uint256, std::pair<NodeId, bool>> mapBlockSource GUARDED_BY(cs_main);

    /** Number of peers with wtxid relay. */
    int m_wtxid_relay_peers GUARDED_BY(cs_main) = 0;

    /** Number of outbound peers with m_chain_sync.m_protect. */
    int m_outbound_peers_with_protect_from_disconnect GUARDED_BY(cs_main) = 0;

    bool AlreadyHaveTx(const GenTxid& gtxid) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /**
     * Filter for transactions that were recently rejected by
     * AcceptToMemoryPool. These are not rerequested until the chain tip
     * changes, at which point the entire filter is reset.
     *
     * Without this filter we'd be re-requesting txs from each of our peers,
     * increasing bandwidth consumption considerably. For instance, with 100
     * peers, half of which relay a tx we don't accept, that might be a 50x
     * bandwidth increase. A flooding attacker attempting to roll-over the
     * filter using minimum-sized, 60byte, transactions might manage to send
     * 1000/sec if we have fast peers, so we pick 120,000 to give our peers a
     * two minute window to send invs to us.
     *
     * Decreasing the false positive rate is fairly cheap, so we pick one in a
     * million to make it highly unlikely for users to have issues with this
     * filter.
     *
     * We typically only add wtxids to this filter. For non-segwit
     * transactions, the txid == wtxid, so this only prevents us from
     * re-downloading non-segwit transactions when communicating with
     * non-wtxidrelay peers -- which is important for avoiding malleation
     * attacks that could otherwise interfere with transaction relay from
     * non-wtxidrelay peers. For communicating with wtxidrelay peers, having
     * the reject filter store wtxids is exactly what we want to avoid
     * redownload of a rejected transaction.
     *
     * In cases where we can tell that a segwit transaction will fail
     * validation no matter the witness, we may add the txid of such
     * transaction to the filter as well. This can be helpful when
     * communicating with txid-relay peers or if we were to otherwise fetch a
     * transaction via txid (eg in our orphan handling).
     *
     * Memory used: 1.3 MB
     */
    CRollingBloomFilter m_recent_rejects GUARDED_BY(::cs_main){120'000, 0.000'001};
    uint256 hashRecentRejectsChainTip GUARDED_BY(cs_main);

    /*
     * Filter for transactions that have been recently confirmed.
     * We use this to avoid requesting transactions that have already been
     * confirnmed.
     *
     * Blocks don't typically have more than 4000 transactions, so this should
     * be at least six blocks (~1 hr) worth of transactions that we can store,
     * inserting both a txid and wtxid for every observed transaction.
     * If the number of transactions appearing in a block goes up, or if we are
     * seeing getdata requests more than an hour after initial announcement, we
     * can increase this number.
     * The false positive rate of 1/1M should come out to less than 1
     * transaction per day that would be inadvertently ignored (which is the
     * same probability that we have in the reject filter).
     */
    Mutex m_recent_confirmed_transactions_mutex;
    CRollingBloomFilter m_recent_confirmed_transactions GUARDED_BY(m_recent_confirmed_transactions_mutex){48'000, 0.000'001};

    /** Have we requested this block from a peer */
    bool IsBlockRequested(const uint256& hash) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /** Remove this block from our tracked requested blocks. Called if:
     *  - the block has been received from a peer
     *  - the request for the block has timed out
     */
    void RemoveBlockRequest(const uint256& hash) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /* Mark a block as in flight
     * Returns false, still setting pit, if the block was already in flight from the same peer
     * pit will only be valid as long as the same cs_main lock is being held
     */
    bool BlockRequested(NodeId nodeid, const CBlockIndex& block, std::list<QueuedBlock>::iterator** pit = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    bool TipMayBeStale() EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /** Update pindexLastCommonBlock and add not-in-flight missing successors to vBlocks, until it has
     *  at most count entries.
     */
    void FindNextBlocksToDownload(NodeId nodeid, unsigned int count, std::vector<const CBlockIndex*>& vBlocks, NodeId& nodeStaller) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    std::map<uint256, std::pair<NodeId, std::list<QueuedBlock>::iterator> > mapBlocksInFlight GUARDED_BY(cs_main);

    /** When our tip was last updated. */
    std::atomic<int64_t> m_last_tip_update{0};

    /** Determine whether or not a peer can request a transaction, and return it (or nullptr if not found or not allowed). */
    CTransactionRef FindTxForGetData(const CNode& peer, const GenTxid& gtxid, const std::chrono::seconds mempool_req, const std::chrono::seconds now) LOCKS_EXCLUDED(cs_main);

    void ProcessGetData(CNode& pfrom, Peer& peer, const std::atomic<bool>& interruptMsgProc) EXCLUSIVE_LOCKS_REQUIRED(peer.m_getdata_requests_mutex) LOCKS_EXCLUDED(::cs_main);

    /** Process a new block. Perform any post-processing housekeeping */
    void ProcessBlock(CNode& node, const std::shared_ptr<const CBlock>& block, bool force_processing);

    /** Relay map (txid or wtxid -> CTransactionRef) */
    typedef std::map<uint256, CTransactionRef> MapRelay;
    MapRelay mapRelay GUARDED_BY(cs_main);
    /** Expiration-time ordered list of (expire time, relay map entry) pairs. */
    std::deque<std::pair<std::chrono::microseconds, MapRelay::iterator>> g_relay_expiration GUARDED_BY(cs_main);

    /**
     * When a peer sends us a valid block, instruct it to announce blocks to us
     * using CMPCTBLOCK if possible by adding its nodeid to the end of
     * lNodesAnnouncingHeaderAndIDs, and keeping that list under a certain size by
     * removing the first element if necessary.
     */
    void MaybeSetPeerAsAnnouncingHeaderAndIDs(NodeId nodeid) EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /** Stack of nodes which we have set to announce using compact blocks */
    std::list<NodeId> lNodesAnnouncingHeaderAndIDs GUARDED_BY(cs_main);

    /** Number of peers from which we're downloading blocks. */
    int m_peers_downloading_from GUARDED_BY(cs_main) = 0;

    /** Storage for orphan information */
    TxOrphanage m_orphanage;

    void AddToCompactExtraTransactions(const CTransactionRef& tx) EXCLUSIVE_LOCKS_REQUIRED(g_cs_orphans);

    /** Orphan/conflicted/etc transactions that are kept for compact block reconstruction.
     *  The last -blockreconstructionextratxn/DEFAULT_BLOCK_RECONSTRUCTION_EXTRA_TXN of
     *  these are kept in a ring buffer */
    std::vector<std::pair<uint256, CTransactionRef>> vExtraTxnForCompact GUARDED_BY(g_cs_orphans);
    /** Offset into vExtraTxnForCompact to insert the next tx */
    size_t vExtraTxnForCompactIt GUARDED_BY(g_cs_orphans) = 0;

    /** Check whether the last unknown block a peer advertised is not yet known. */
    void ProcessBlockAvailability(NodeId nodeid) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    /** Update tracking information about which blocks a peer is assumed to have. */
    void UpdateBlockAvailability(NodeId nodeid, const uint256& hash) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    bool CanDirectFetch() EXCLUSIVE_LOCKS_REQUIRED(cs_main);

    /**
     * To prevent fingerprinting attacks, only send blocks/headers outside of
     * the active chain if they are no more than a month older (both in time,
     * and in best equivalent proof of work) than the best header chain we know
     * about and we fully-validated them at some point.
     */
    bool BlockRequestAllowed(const CBlockIndex* pindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    bool AlreadyHaveBlock(const uint256& block_hash) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
    void ProcessGetBlockData(CNode& pfrom, Peer& peer, const CInv& inv);

    /**
     * Validation logic for compact filters request handling.
     *
     * May disconnect from the peer in the case of a bad request.
     *
     * @param[in]   peer            The peer that we received the request from
     * @param[in]   filter_type     The filter type the request is for. Must be basic filters.
     * @param[in]   start_height    The start height for the request
     * @param[in]   stop_hash       The stop_hash for the request
     * @param[in]   max_height_diff The maximum number of items permitted to request, as specified in BIP 157
     * @param[out]  stop_index      The CBlockIndex for the stop_hash block, if the request can be serviced.
     * @param[out]  filter_index    The filter index, if the request can be serviced.
     * @return                      True if the request can be serviced.
     */
    bool PrepareBlockFilterRequest(CNode& peer,
                                   BlockFilterType filter_type, uint32_t start_height,
                                   const uint256& stop_hash, uint32_t max_height_diff,
                                   const CBlockIndex*& stop_index,
                                   BlockFilterIndex*& filter_index);

    /**
     * Handle a cfilters request.
     *
     * May disconnect from the peer in the case of a bad request.
     *
     * @param[in]   peer            The peer that we received the request from
     * @param[in]   vRecv           The raw message received
     */
    void ProcessGetCFilters(CNode& peer, CDataStream& vRecv);

    /**
     * Handle a cfheaders request.
     *
     * May disconnect from the peer in the case of a bad request.
     *
     * @param[in]   peer            The peer that we received the request from
     * @param[in]   vRecv           The raw message received
     */
    void ProcessGetCFHeaders(CNode& peer, CDataStream& vRecv);

    /**
     * Handle a getcfcheckpt request.
     *
     * May disconnect from the peer in the case of a bad request.
     *
     * @param[in]   peer            The peer that we received the request from
     * @param[in]   vRecv           The raw message received
     */
    void ProcessGetCFCheckPt(CNode& peer, CDataStream& vRecv);

    /** Checks if address relay is permitted with peer. If needed, initializes
     * the m_addr_known bloom filter and sets m_addr_relay_enabled to true.
     *
     *  @return   True if address relay is enabled with peer
     *            False if address relay is disallowed
     */
    bool SetupAddressRelay(const CNode& node, Peer& peer);
};
} // namespace

namespace {
    /** Number of preferable block download peers. */
    int nPreferredDownload GUARDED_BY(cs_main) = 0;
} // namespace

namespace {
/**
 * Maintain validation-specific state about nodes, protected by cs_main, instead
 * by CNode's own locks. This simplifies asynchronous operation, where
 * processing of incoming data is done after the ProcessMessage call returns,
 * and we're no longer holding the node's locks.
 */
struct CNodeState {
    //! The best known block we know this peer has announced.
    const CBlockIndex* pindexBestKnownBlock{nullptr};
    //! The hash of the last unknown block this peer has announced.
    uint256 hashLastUnknownBlock{};
    //! The last full block we both have.
    const CBlockIndex* pindexLastCommonBlock{nullptr};
    //! The best header we have sent our peer.
    const CBlockIndex* pindexBestHeaderSent{nullptr};
    //! Length of current-streak of unconnecting headers announcements
    int nUnconnectingHeaders{0};
    //! Whether we've started headers synchronization with this peer.
    bool fSyncStarted{false};
    //! When to potentially disconnect peer for stalling headers download
    std::chrono::microseconds m_headers_sync_timeout{0us};
    //! Since when we're stalling block download progress (in microseconds), or 0.
    std::chrono::microseconds m_stalling_since{0us};
    std::list<QueuedBlock> vBlocksInFlight;
    //! When the first entry in vBlocksInFlight started downloading. Don't care when vBlocksInFlight is empty.
    std::chrono::microseconds m_downloading_since{0us};
    int nBlocksInFlight{0};
    //! Whether we consider this a preferred download peer.
    bool fPreferredDownload{false};
    //! Whether this peer wants invs or headers (when possible) for block announcements.
    bool fPreferHeaders{false};
    //! Whether this peer wants invs or cmpctblocks (when possible) for block announcements.
    bool fPreferHeaderAndIDs{false};
    /**
      * Whether this peer will send us cmpctblocks if we request them.
      * This is not used to gate request logic, as we really only care about fSupportsDesiredCmpctVersion,
      * but is used as a flag to "lock in" the version of compact blocks (fWantsCmpctWitness) we send.
      */
    bool fProvidesHeaderAndIDs{false};
    //! Whether this peer can give us witnesses
    bool fHaveWitness{false};
    //! Whether this peer wants witnesses in cmpctblocks/blocktxns
    bool fWantsCmpctWitness{false};
    /**
     * If we've announced NODE_WITNESS to this peer: whether the peer sends witnesses in cmpctblocks/blocktxns,
     * otherwise: whether this peer sends non-witnesses in cmpctblocks/blocktxns.
     */
    bool fSupportsDesiredCmpctVersion{false};

    /** State used to enforce CHAIN_SYNC_TIMEOUT and EXTRA_PEER_CHECK_INTERVAL logic.
      *
      * Both are only in effect for outbound, non-manual, non-protected connections.
      * Any peer protected (m_protect = true) is not chosen for eviction. A peer is
      * marked as protected if all of these are true:
      *   - its connection type is IsBlockOnlyConn() == false
      *   - it gave us a valid connecting header
      *   - we haven't reached MAX_OUTBOUND_PEERS_TO_PROTECT_FROM_DISCONNECT yet
      *   - its chain tip has at least as much work as ours
      *
      * CHAIN_SYNC_TIMEOUT: if a peer's best known block has less work than our tip,
      * set a timeout CHAIN_SYNC_TIMEOUT seconds in the future:
      *   - If at timeout their best known block now has more work than our tip
      *     when the timeout was set, then either reset the timeout or clear it
      *     (after comparing against our current tip's work)
      *   - If at timeout their best known block still has less work than our
      *     tip did when the timeout was set, then send a getheaders message,
      *     and set a shorter timeout, HEADERS_RESPONSE_TIME seconds in future.
      *     If their best known block is still behind when that new timeout is
      *     reached, disconnect.
      *
      * EXTRA_PEER_CHECK_INTERVAL: after each interval, if we have too many outbound peers,
      * drop the outbound one that least recently announced us a new block.
      */
    struct ChainSyncTimeoutState {
        //! A timeout used for checking whether our peer has sufficiently synced
        int64_t m_timeout{0};
        //! A header with the work we require on our peer's chain
        const CBlockIndex* m_work_header{nullptr};
        //! After timeout is reached, set to true after sending getheaders
        bool m_sent_getheaders{false};
        //! Whether this peer is protected from disconnection due to a bad/slow chain
        bool m_protect{false};
    };

    ChainSyncTimeoutState m_chain_sync;

    //! Time of last new block announcement
    int64_t m_last_block_announcement{0};

    //! Whether this peer is an inbound connection
    const bool m_is_inbound;

    //! A rolling bloom filter of all announced tx CInvs to this peer.
    CRollingBloomFilter m_recently_announced_invs = CRollingBloomFilter{INVENTORY_MAX_RECENT_RELAY, 0.000001};

    //! Whether this peer relays txs via wtxid
    bool m_wtxid_relay{false};

    CNodeState(bool is_inbound) : m_is_inbound(is_inbound) {}
};

/** Map maintaining per-node state. */
static std::map<NodeId, CNodeState> mapNodeState GUARDED_BY(cs_main);

static CNodeState *State(NodeId pnode) EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
    std::map<NodeId, CNodeState>::iterator it = mapNodeState.find(pnode);
    if (it == mapNodeState.end())
        return nullptr;
    return &it->second;
}

/**
 * Whether the peer supports the address. For example, a peer that does not
 * implement BIP155 cannot receive Tor v3 addresses because it requires
 * ADDRv2 (BIP155) encoding.
 */
static bool IsAddrCompatible(const Peer& peer, const CAddress& addr)
{
    return peer.m_wants_addrv2 || addr.IsAddrV1Compatible();
}

static void AddAddressKnown(Peer& peer, const CAddress& addr)
{
    assert(peer.m_addr_known);
    peer.m_addr_known->insert(addr.GetKey());
}

static void PushAddress(Peer& peer, const CAddress& addr, FastRandomContext& insecure_rand)
{
    // Known checking here is only to save space from duplicates.
    // Before sending, we'll filter it again for known addresses that were
    // added after addresses were pushed.
    assert(peer.m_addr_known);
    if (addr.IsValid() && !peer.m_addr_known->contains(addr.GetKey()) && IsAddrCompatible(peer, addr)) {
        if (peer.m_addrs_to_send.size() >= MAX_ADDR_TO_SEND) {
            peer.m_addrs_to_send[insecure_rand.randrange(peer.m_addrs_to_send.size())] = addr;
        } else {
            peer.m_addrs_to_send.push_back(addr);
        }
    }
}

static void UpdatePreferredDownload(const CNode& node, CNodeState* state) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    nPreferredDownload -= state->fPreferredDownload;

    // Whether this node should be marked as a preferred download node.
    state->fPreferredDownload = (!node.IsInboundConn() || node.HasPermission(NetPermissionFlags::NoBan)) && !node.IsAddrFetchConn() && !node.fClient;

    nPreferredDownload += state->fPreferredDownload;
}

bool PeerManagerImpl::IsBlockRequested(const uint256& hash)
{
    return mapBlocksInFlight.find(hash) != mapBlocksInFlight.end();
}

void PeerManagerImpl::RemoveBlockRequest(const uint256& hash)
{
    auto it = mapBlocksInFlight.find(hash);
    if (it == mapBlocksInFlight.end()) {
        // Block was not requested
        return;
    }

    auto [node_id, list_it] = it->second;
    CNodeState *state = State(node_id);
    assert(state != nullptr);

    if (state->vBlocksInFlight.begin() == list_it) {
        // First block on the queue was received, update the start download time for the next one
        state->m_downloading_since = std::max(state->m_downloading_since, GetTime<std::chrono::microseconds>());
    }
    state->vBlocksInFlight.erase(list_it);

    state->nBlocksInFlight--;
    if (state->nBlocksInFlight == 0) {
        // Last validated block on the queue was received.
        m_peers_downloading_from--;
    }
    state->m_stalling_since = 0us;
    mapBlocksInFlight.erase(it);
}

bool PeerManagerImpl::BlockRequested(NodeId nodeid, const CBlockIndex& block, std::list<QueuedBlock>::iterator** pit)
{
    const uint256& hash{block.GetBlockHash()};

    CNodeState *state = State(nodeid);
    assert(state != nullptr);

    // Short-circuit most stuff in case it is from the same node
    std::map<uint256, std::pair<NodeId, std::list<QueuedBlock>::iterator> >::iterator itInFlight = mapBlocksInFlight.find(hash);
    if (itInFlight != mapBlocksInFlight.end() && itInFlight->second.first == nodeid) {
        if (pit) {
            *pit = &itInFlight->second.second;
        }
        return false;
    }

    // Make sure it's not listed somewhere already.
    RemoveBlockRequest(hash);

    std::list<QueuedBlock>::iterator it = state->vBlocksInFlight.insert(state->vBlocksInFlight.end(),
            {&block, std::unique_ptr<PartiallyDownloadedBlock>(pit ? new PartiallyDownloadedBlock(&m_mempool) : nullptr)});
    state->nBlocksInFlight++;
    if (state->nBlocksInFlight == 1) {
        // We're starting a block download (batch) from this peer.
        state->m_downloading_since = GetTime<std::chrono::microseconds>();
        m_peers_downloading_from++;
    }
    itInFlight = mapBlocksInFlight.insert(std::make_pair(hash, std::make_pair(nodeid, it))).first;
    if (pit) {
        *pit = &itInFlight->second.second;
    }
    return true;
}

void PeerManagerImpl::MaybeSetPeerAsAnnouncingHeaderAndIDs(NodeId nodeid)
{
    AssertLockHeld(cs_main);
    CNodeState* nodestate = State(nodeid);
    if (!nodestate || !nodestate->fSupportsDesiredCmpctVersion) {
        // Never ask from peers who can't provide witnesses.
        return;
    }
    if (nodestate->fProvidesHeaderAndIDs) {
        int num_outbound_hb_peers = 0;
        for (std::list<NodeId>::iterator it = lNodesAnnouncingHeaderAndIDs.begin(); it != lNodesAnnouncingHeaderAndIDs.end(); it++) {
            if (*it == nodeid) {
                lNodesAnnouncingHeaderAndIDs.erase(it);
                lNodesAnnouncingHeaderAndIDs.push_back(nodeid);
                return;
            }
            CNodeState *state = State(*it);
            if (state != nullptr && !state->m_is_inbound) ++num_outbound_hb_peers;
        }
        if (nodestate->m_is_inbound) {
            // If we're adding an inbound HB peer, make sure we're not removing
            // our last outbound HB peer in the process.
            if (lNodesAnnouncingHeaderAndIDs.size() >= 3 && num_outbound_hb_peers == 1) {
                CNodeState *remove_node = State(lNodesAnnouncingHeaderAndIDs.front());
                if (remove_node != nullptr && !remove_node->m_is_inbound) {
                    // Put the HB outbound peer in the second slot, so that it
                    // doesn't get removed.
                    std::swap(lNodesAnnouncingHeaderAndIDs.front(), *std::next(lNodesAnnouncingHeaderAndIDs.begin()));
                }
            }
        }
        m_connman.ForNode(nodeid, [this](CNode* pfrom) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
            AssertLockHeld(::cs_main);
            uint64_t nCMPCTBLOCKVersion = 2;
            if (lNodesAnnouncingHeaderAndIDs.size() >= 3) {
                // As per BIP152, we only get 3 of our peers to announce
                // blocks using compact encodings.
                m_connman.ForNode(lNodesAnnouncingHeaderAndIDs.front(), [this, nCMPCTBLOCKVersion](CNode* pnodeStop){
                    m_connman.PushMessage(pnodeStop, CNetMsgMaker(pnodeStop->GetCommonVersion()).Make(NetMsgType::SENDCMPCT, /*fAnnounceUsingCMPCTBLOCK=*/false, nCMPCTBLOCKVersion));
                    // save BIP152 bandwidth state: we select peer to be low-bandwidth
                    pnodeStop->m_bip152_highbandwidth_to = false;
                    return true;
                });
                lNodesAnnouncingHeaderAndIDs.pop_front();
            }
            m_connman.PushMessage(pfrom, CNetMsgMaker(pfrom->GetCommonVersion()).Make(NetMsgType::SENDCMPCT, /*fAnnounceUsingCMPCTBLOCK=*/true, nCMPCTBLOCKVersion));
            // save BIP152 bandwidth state: we select peer to be high-bandwidth
            pfrom->m_bip152_highbandwidth_to = true;
            lNodesAnnouncingHeaderAndIDs.push_back(pfrom->GetId());
            return true;
        });
    }
}

bool PeerManagerImpl::TipMayBeStale()
{
    AssertLockHeld(cs_main);
    const Consensus::Params& consensusParams = m_chainparams.GetConsensus();
    if (m_last_tip_update == 0) {
        m_last_tip_update = GetTime();
    }
    return m_last_tip_update < GetTime() - consensusParams.nPowTargetSpacing * 3 && mapBlocksInFlight.empty();
}

bool PeerManagerImpl::CanDirectFetch()
{
    return m_chainman.ActiveChain().Tip()->GetBlockTime() > GetAdjustedTime() - m_chainparams.GetConsensus().nPowTargetSpacing * 20;
}

static bool PeerHasHeader(CNodeState *state, const CBlockIndex *pindex) EXCLUSIVE_LOCKS_REQUIRED(cs_main)
{
    if (state->pindexBestKnownBlock && pindex == state->pindexBestKnownBlock->GetAncestor(pindex->nHeight))
        return true;
    if (state->pindexBestHeaderSent && pindex == state->pindexBestHeaderSent->GetAncestor(pindex->nHeight))
        return true;
    return false;
}

void PeerManagerImpl::ProcessBlockAvailability(NodeId nodeid) {
    CNodeState *state = State(nodeid);
    assert(state != nullptr);

    if (!state->hashLastUnknownBlock.IsNull()) {
        const CBlockIndex* pindex = m_chainman.m_blockman.LookupBlockIndex(state->hashLastUnknownBlock);
        if (pindex && pindex->nChainWork > 0) {
            if (state->pindexBestKnownBlock == nullptr || pindex->nChainWork >= state->pindexBestKnownBlock->nChainWork) {
                state->pindexBestKnownBlock = pindex;
            }
            state->hashLastUnknownBlock.SetNull();
        }
    }
}

void PeerManagerImpl::UpdateBlockAvailability(NodeId nodeid, const uint256 &hash) {
    CNodeState *state = State(nodeid);
    assert(state != nullptr);

    ProcessBlockAvailability(nodeid);

    const CBlockIndex* pindex = m_chainman.m_blockman.LookupBlockIndex(hash);
    if (pindex && pindex->nChainWork > 0) {
        // An actually better block was announced.
        if (state->pindexBestKnownBlock == nullptr || pindex->nChainWork >= state->pindexBestKnownBlock->nChainWork) {
            state->pindexBestKnownBlock = pindex;
        }
    } else {
        // An unknown block was announced; just assume that the latest one is the best one.
        state->hashLastUnknownBlock = hash;
    }
}

void PeerManagerImpl::FindNextBlocksToDownload(NodeId nodeid, unsigned int count, std::vector<const CBlockIndex*>& vBlocks, NodeId& nodeStaller)
{
    if (count == 0)
        return;

    vBlocks.reserve(vBlocks.size() + count);
    CNodeState *state = State(nodeid);
    assert(state != nullptr);

    // Make sure pindexBestKnownBlock is up to date, we'll need it.
    ProcessBlockAvailability(nodeid);

    if (state->pindexBestKnownBlock == nullptr || state->pindexBestKnownBlock->nChainWork < m_chainman.ActiveChain().Tip()->nChainWork || state->pindexBestKnownBlock->nChainWork < nMinimumChainWork) {
        // This peer has nothing interesting.
        return;
    }

    if (state->pindexLastCommonBlock == nullptr) {
        // Bootstrap quickly by guessing a parent of our best tip is the forking point.
        // Guessing wrong in either direction is not a problem.
        state->pindexLastCommonBlock = m_chainman.ActiveChain()[std::min(state->pindexBestKnownBlock->nHeight, m_chainman.ActiveChain().Height())];
    }

    // If the peer reorganized, our previous pindexLastCommonBlock may not be an ancestor
    // of its current tip anymore. Go back enough to fix that.
    state->pindexLastCommonBlock = LastCommonAncestor(state->pindexLastCommonBlock, state->pindexBestKnownBlock);
    if (state->pindexLastCommonBlock == state->pindexBestKnownBlock)
        return;

    const Consensus::Params& consensusParams = m_chainparams.GetConsensus();
    std::vector<const CBlockIndex*> vToFetch;
    const CBlockIndex *pindexWalk = state->pindexLastCommonBlock;
    // Never fetch further than the best block we know the peer has, or more than BLOCK_DOWNLOAD_WINDOW + 1 beyond the last
    // linked block we have in common with this peer. The +1 is so we can detect stalling, namely if we would be able to
    // download that next block if the window were 1 larger.
    int nWindowEnd = state->pindexLastCommonBlock->nHeight + BLOCK_DOWNLOAD_WINDOW;
    int nMaxHeight = std::min<int>(state->pindexBestKnownBlock->nHeight, nWindowEnd + 1);
    NodeId waitingfor = -1;
    while (pindexWalk->nHeight < nMaxHeight) {
        // Read up to 128 (or more, if more blocks than that are needed) successors of pindexWalk (towards
        // pindexBestKnownBlock) into vToFetch. We fetch 128, because CBlockIndex::GetAncestor may be as expensive
        // as iterating over ~100 CBlockIndex* entries anyway.
        int nToFetch = std::min(nMaxHeight - pindexWalk->nHeight, std::max<int>(count - vBlocks.size(), 128));
        vToFetch.resize(nToFetch);
        pindexWalk = state->pindexBestKnownBlock->GetAncestor(pindexWalk->nHeight + nToFetch);
        vToFetch[nToFetch - 1] = pindexWalk;
        for (unsigned int i = nToFetch - 1; i > 0; i--) {
            vToFetch[i - 1] = vToFetch[i]->pprev;
        }

        // Iterate over those blocks in vToFetch (in forward direction), adding the ones that
        // are not yet downloaded and not in flight to vBlocks. In the meantime, update
        // pindexLastCommonBlock as long as all ancestors are already downloaded, or if it's
        // already part of our chain (and therefore don't need it even if pruned).
        for (const CBlockIndex* pindex : vToFetch) {
            if (!pindex->IsValid(BLOCK_VALID_TREE)) {
                // We consider the chain that this peer is on invalid.
                return;
            }
            if (!State(nodeid)->fHaveWitness && DeploymentActiveAt(*pindex, consensusParams, Consensus::DEPLOYMENT_SEGWIT)) {
                // We wouldn't download this block or its descendants from this peer.
                return;
            }
            if (pindex->nStatus & BLOCK_HAVE_DATA || m_chainman.ActiveChain().Contains(pindex)) {
                if (pindex->HaveTxsDownloaded())
                    state->pindexLastCommonBlock = pindex;
            } else if (!IsBlockRequested(pindex->GetBlockHash())) {
                // The block is not already downloaded, and not yet in flight.
                if (pindex->nHeight > nWindowEnd) {
                    // We reached the end of the window.
                    if (vBlocks.size() == 0 && waitingfor != nodeid) {
                        // We aren't able to fetch anything, but we would be if the download window was one larger.
                        nodeStaller = waitingfor;
                    }
                    return;
                }
                vBlocks.push_back(pindex);
                if (vBlocks.size() == count) {
                    return;
                }
            } else if (waitingfor == -1) {
                // This is the first already-in-flight block.
                waitingfor = mapBlocksInFlight[pindex->GetBlockHash()].first;
            }
        }
    }
}

} // namespace

void PeerManagerImpl::PushNodeVersion(CNode& pnode, int64_t nTime)
{
    // Note that pnode->GetLocalServices() is a reflection of the local
    // services we were offering when the CNode object was created for this
    // peer.
    uint64_t my_services{pnode.GetLocalServices()};
    uint64_t nonce = pnode.GetLocalNonce();
    const int nNodeStartingHeight{m_best_height};
    NodeId nodeid = pnode.GetId();
    CAddress addr = pnode.addr;

    CService addr_you = addr.IsRoutable() && !IsProxy(addr) && addr.IsAddrV1Compatible() ? addr : CService();
    uint64_t your_services{addr.nServices};

    const bool tx_relay = !m_ignore_incoming_txs && pnode.m_tx_relay != nullptr;
    m_connman.PushMessage(&pnode, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::VERSION, PROTOCOL_VERSION, my_services, nTime,
            your_services, addr_you, // Together the pre-version-31402 serialization of CAddress "addrYou" (without nTime)
            my_services, CService(), // Together the pre-version-31402 serialization of CAddress "addrMe" (without nTime)
            nonce, strSubVersion, nNodeStartingHeight, tx_relay));

    if (fLogIPs) {
        LogPrint(BCLog::NET, "send version message: version %d, blocks=%d, them=%s, txrelay=%d, peer=%d\n", PROTOCOL_VERSION, nNodeStartingHeight, addr_you.ToString(), tx_relay, nodeid);
    } else {
        LogPrint(BCLog::NET, "send version message: version %d, blocks=%d, txrelay=%d, peer=%d\n", PROTOCOL_VERSION, nNodeStartingHeight, tx_relay, nodeid);
    }
}

void PeerManagerImpl::AddTxAnnouncement(const CNode& node, const GenTxid& gtxid, std::chrono::microseconds current_time)
{
    AssertLockHeld(::cs_main); // For m_txrequest
    NodeId nodeid = node.GetId();
    if (!node.HasPermission(NetPermissionFlags::Relay) && m_txrequest.Count(nodeid) >= MAX_PEER_TX_ANNOUNCEMENTS) {
        // Too many queued announcements from this peer
        return;
    }
    const CNodeState* state = State(nodeid);

    // Decide the TxRequestTracker parameters for this announcement:
    // - "preferred": if fPreferredDownload is set (= outbound, or NetPermissionFlags::NoBan permission)
    // - "reqtime": current time plus delays for:
    //   - NONPREF_PEER_TX_DELAY for announcements from non-preferred connections
    //   - TXID_RELAY_DELAY for txid announcements while wtxid peers are available
    //   - OVERLOADED_PEER_TX_DELAY for announcements from peers which have at least
    //     MAX_PEER_TX_REQUEST_IN_FLIGHT requests in flight (and don't have NetPermissionFlags::Relay).
    auto delay = std::chrono::microseconds{0};
    const bool preferred = state->fPreferredDownload;
    if (!preferred) delay += NONPREF_PEER_TX_DELAY;
    if (!gtxid.IsWtxid() && m_wtxid_relay_peers > 0) delay += TXID_RELAY_DELAY;
    const bool overloaded = !node.HasPermission(NetPermissionFlags::Relay) &&
        m_txrequest.CountInFlight(nodeid) >= MAX_PEER_TX_REQUEST_IN_FLIGHT;
    if (overloaded) delay += OVERLOADED_PEER_TX_DELAY;
    m_txrequest.ReceivedInv(nodeid, gtxid, preferred, current_time + delay);
}

// This function is used for testing the stale tip eviction logic, see
// denialofservice_tests.cpp
void UpdateLastBlockAnnounceTime(NodeId node, int64_t time_in_seconds)
{
    LOCK(cs_main);
    CNodeState *state = State(node);
    if (state) state->m_last_block_announcement = time_in_seconds;
}

void PeerManagerImpl::InitializeNode(CNode *pnode)
{
    NodeId nodeid = pnode->GetId();
    {
        LOCK(cs_main);
        mapNodeState.emplace_hint(mapNodeState.end(), std::piecewise_construct, std::forward_as_tuple(nodeid), std::forward_as_tuple(pnode->IsInboundConn()));
        assert(m_txrequest.Count(nodeid) == 0);
    }
    {
        PeerRef peer = std::make_shared<Peer>(nodeid);
        LOCK(m_peer_mutex);
        m_peer_map.emplace_hint(m_peer_map.end(), nodeid, std::move(peer));
    }
    if (!pnode->IsInboundConn()) {
        PushNodeVersion(*pnode, GetTime());
    }
}

void PeerManagerImpl::ReattemptInitialBroadcast(CScheduler& scheduler)
{
    std::set<uint256> unbroadcast_txids = m_mempool.GetUnbroadcastTxs();

    for (const auto& txid : unbroadcast_txids) {
        CTransactionRef tx = m_mempool.get(txid);

        if (tx != nullptr) {
            LOCK(cs_main);
            _RelayTransaction(txid, tx->GetWitnessHash());
        } else {
            m_mempool.RemoveUnbroadcastTx(txid, true);
        }
    }

    // Schedule next run for 10-15 minutes in the future.
    // We add randomness on every cycle to avoid the possibility of P2P fingerprinting.
    const std::chrono::milliseconds delta = std::chrono::minutes{10} + GetRandMillis(std::chrono::minutes{5});
    scheduler.scheduleFromNow([&] { ReattemptInitialBroadcast(scheduler); }, delta);
}

void PeerManagerImpl::FinalizeNode(const CNode& node)
{
    NodeId nodeid = node.GetId();
    int misbehavior{0};
    {
    LOCK(cs_main);
    {
        // We remove the PeerRef from g_peer_map here, but we don't always
        // destruct the Peer. Sometimes another thread is still holding a
        // PeerRef, so the refcount is >= 1. Be careful not to do any
        // processing here that assumes Peer won't be changed before it's
        // destructed.
        PeerRef peer = RemovePeer(nodeid);
        assert(peer != nullptr);
        misbehavior = WITH_LOCK(peer->m_misbehavior_mutex, return peer->m_misbehavior_score);
    }
    CNodeState *state = State(nodeid);
    assert(state != nullptr);

    if (state->fSyncStarted)
        nSyncStarted--;

    for (const QueuedBlock& entry : state->vBlocksInFlight) {
        mapBlocksInFlight.erase(entry.pindex->GetBlockHash());
    }
    WITH_LOCK(g_cs_orphans, m_orphanage.EraseForPeer(nodeid));
    m_txrequest.DisconnectedPeer(nodeid);
    nPreferredDownload -= state->fPreferredDownload;
    m_peers_downloading_from -= (state->nBlocksInFlight != 0);
    assert(m_peers_downloading_from >= 0);
    m_outbound_peers_with_protect_from_disconnect -= state->m_chain_sync.m_protect;
    assert(m_outbound_peers_with_protect_from_disconnect >= 0);
    m_wtxid_relay_peers -= state->m_wtxid_relay;
    assert(m_wtxid_relay_peers >= 0);

    mapNodeState.erase(nodeid);

    if (mapNodeState.empty()) {
        // Do a consistency check after the last peer is removed.
        assert(mapBlocksInFlight.empty());
        assert(nPreferredDownload == 0);
        assert(m_peers_downloading_from == 0);
        assert(m_outbound_peers_with_protect_from_disconnect == 0);
        assert(m_wtxid_relay_peers == 0);
        assert(m_txrequest.Size() == 0);
        assert(m_orphanage.Size() == 0);
    }
    } // cs_main
    if (node.fSuccessfullyConnected && misbehavior == 0 &&
        !node.IsBlockOnlyConn() && !node.IsInboundConn()) {
        // Only change visible addrman state for full outbound peers.  We don't
        // call Connected() for feeler connections since they don't have
        // fSuccessfullyConnected set.
        m_addrman.Connected(node.addr);
    }
    LogPrint(BCLog::NET, "Cleared nodestate for peer=%d\n", nodeid);
}

PeerRef PeerManagerImpl::GetPeerRef(NodeId id) const
{
    LOCK(m_peer_mutex);
    auto it = m_peer_map.find(id);
    return it != m_peer_map.end() ? it->second : nullptr;
}

PeerRef PeerManagerImpl::RemovePeer(NodeId id)
{
    PeerRef ret;
    LOCK(m_peer_mutex);
    auto it = m_peer_map.find(id);
    if (it != m_peer_map.end()) {
        ret = std::move(it->second);
        m_peer_map.erase(it);
    }
    return ret;
}

bool PeerManagerImpl::GetNodeStateStats(NodeId nodeid, CNodeStateStats& stats) const
{
    {
        LOCK(cs_main);
        CNodeState* state = State(nodeid);
        if (state == nullptr)
            return false;
        stats.nSyncHeight = state->pindexBestKnownBlock ? state->pindexBestKnownBlock->nHeight : -1;
        stats.nCommonHeight = state->pindexLastCommonBlock ? state->pindexLastCommonBlock->nHeight : -1;
        for (const QueuedBlock& queue : state->vBlocksInFlight) {
            if (queue.pindex)
                stats.vHeightInFlight.push_back(queue.pindex->nHeight);
        }
    }

    PeerRef peer = GetPeerRef(nodeid);
    if (peer == nullptr) return false;
    stats.m_starting_height = peer->m_starting_height;
    // It is common for nodes with good ping times to suddenly become lagged,
    // due to a new block arriving or other large transfer.
    // Merely reporting pingtime might fool the caller into thinking the node was still responsive,
    // since pingtime does not update until the ping is complete, which might take a while.
    // So, if a ping is taking an unusually long time in flight,
    // the caller can immediately detect that this is happening.
    std::chrono::microseconds ping_wait{0};
    if ((0 != peer->m_ping_nonce_sent) && (0 != peer->m_ping_start.load().count())) {
        ping_wait = GetTime<std::chrono::microseconds>() - peer->m_ping_start.load();
    }

    stats.m_ping_wait = ping_wait;
    stats.m_addr_processed = peer->m_addr_processed.load();
    stats.m_addr_rate_limited = peer->m_addr_rate_limited.load();
    stats.m_addr_relay_enabled = peer->m_addr_relay_enabled.load();

    return true;
}

void PeerManagerImpl::AddToCompactExtraTransactions(const CTransactionRef& tx)
{
    size_t max_extra_txn = gArgs.GetArg("-blockreconstructionextratxn", DEFAULT_BLOCK_RECONSTRUCTION_EXTRA_TXN);
    if (max_extra_txn <= 0)
        return;
    if (!vExtraTxnForCompact.size())
        vExtraTxnForCompact.resize(max_extra_txn);
    vExtraTxnForCompact[vExtraTxnForCompactIt] = std::make_pair(tx->GetWitnessHash(), tx);
    vExtraTxnForCompactIt = (vExtraTxnForCompactIt + 1) % max_extra_txn;
}

void PeerManagerImpl::Misbehaving(const NodeId pnode, const int howmuch, const std::string& message)
{
    assert(howmuch > 0);

    PeerRef peer = GetPeerRef(pnode);
    if (peer == nullptr) return;

    LOCK(peer->m_misbehavior_mutex);
    const int score_before{peer->m_misbehavior_score};
    peer->m_misbehavior_score += howmuch;
    const int score_now{peer->m_misbehavior_score};

    const std::string message_prefixed = message.empty() ? "" : (": " + message);
    std::string warning;

    if (score_now >= DISCOURAGEMENT_THRESHOLD && score_before < DISCOURAGEMENT_THRESHOLD) {
        warning = " DISCOURAGE THRESHOLD EXCEEDED";
        peer->m_should_discourage = true;
    }

    LogPrint(BCLog::NET, "Misbehaving: peer=%d (%d -> %d)%s%s\n",
             pnode, score_before, score_now, warning, message_prefixed);
}

bool PeerManagerImpl::MaybePunishNodeForBlock(NodeId nodeid, const BlockValidationState& state,
                                              bool via_compact_block, const std::string& message)
{
    switch (state.GetResult()) {
    case BlockValidationResult::BLOCK_RESULT_UNSET:
        break;
    // The node is providing invalid data:
    case BlockValidationResult::BLOCK_CONSENSUS:
    case BlockValidationResult::BLOCK_MUTATED:
        if (!via_compact_block) {
            Misbehaving(nodeid, 100, message);
            return true;
        }
        break;
    case BlockValidationResult::BLOCK_CACHED_INVALID:
        {
            LOCK(cs_main);
            CNodeState *node_state = State(nodeid);
            if (node_state == nullptr) {
                break;
            }

            // Discourage outbound (but not inbound) peers if on an invalid chain.
            // Exempt HB compact block peers. Manual connections are always protected from discouragement.
            if (!via_compact_block && !node_state->m_is_inbound) {
                Misbehaving(nodeid, 100, message);
                return true;
            }
            break;
        }
    case BlockValidationResult::BLOCK_INVALID_HEADER:
    case BlockValidationResult::BLOCK_CHECKPOINT:
    case BlockValidationResult::BLOCK_INVALID_PREV:
        Misbehaving(nodeid, 100, message);
        return true;
    // Conflicting (but not necessarily invalid) data or different policy:
    case BlockValidationResult::BLOCK_MISSING_PREV:
        // TODO: Handle this much more gracefully (10 DoS points is super arbitrary)
        Misbehaving(nodeid, 10, message);
        return true;
    case BlockValidationResult::BLOCK_RECENT_CONSENSUS_CHANGE:
    case BlockValidationResult::BLOCK_TIME_FUTURE:
        break;
    }
    if (message != "") {
        LogPrint(BCLog::NET, "peer=%d: %s\n", nodeid, message);
    }
    return false;
}

bool PeerManagerImpl::MaybePunishNodeForTx(NodeId nodeid, const TxValidationState& state, const std::string& message)
{
    switch (state.GetResult()) {
    case TxValidationResult::TX_RESULT_UNSET:
        break;
    // The node is providing invalid data:
    case TxValidationResult::TX_CONSENSUS:
        Misbehaving(nodeid, 100, message);
        return true;
    // Conflicting (but not necessarily invalid) data or different policy:
    case TxValidationResult::TX_RECENT_CONSENSUS_CHANGE:
    case TxValidationResult::TX_INPUTS_NOT_STANDARD:
    case TxValidationResult::TX_NOT_STANDARD:
    case TxValidationResult::TX_MISSING_INPUTS:
    case TxValidationResult::TX_PREMATURE_SPEND:
    case TxValidationResult::TX_WITNESS_MUTATED:
    case TxValidationResult::TX_WITNESS_STRIPPED:
    case TxValidationResult::TX_CONFLICT:
    case TxValidationResult::TX_MEMPOOL_POLICY:
        break;
    }
    if (message != "") {
        LogPrint(BCLog::NET, "peer=%d: %s\n", nodeid, message);
    }
    return false;
}

bool PeerManagerImpl::BlockRequestAllowed(const CBlockIndex* pindex)
{
    AssertLockHeld(cs_main);
    if (m_chainman.ActiveChain().Contains(pindex)) return true;
    return pindex->IsValid(BLOCK_VALID_SCRIPTS) && (pindexBestHeader != nullptr) &&
           (pindexBestHeader->GetBlockTime() - pindex->GetBlockTime() < STALE_RELAY_AGE_LIMIT) &&
           (GetBlockProofEquivalentTime(*pindexBestHeader, *pindex, *pindexBestHeader, m_chainparams.GetConsensus()) < STALE_RELAY_AGE_LIMIT);
}

std::unique_ptr<PeerManager> PeerManager::make(const CChainParams& chainparams, CConnman& connman, CAddrMan& addrman,
                                               BanMan* banman, ChainstateManager& chainman,
                                               CTxMemPool& pool, bool ignore_incoming_txs)
{
    return std::make_unique<PeerManagerImpl>(chainparams, connman, addrman, banman, chainman, pool, ignore_incoming_txs);
}

PeerManagerImpl::PeerManagerImpl(const CChainParams& chainparams, CConnman& connman, CAddrMan& addrman,
                                 BanMan* banman, ChainstateManager& chainman,
                                 CTxMemPool& pool, bool ignore_incoming_txs)
    : m_chainparams(chainparams),
      m_connman(connman),
      m_addrman(addrman),
      m_banman(banman),
      m_chainman(chainman),
      m_mempool(pool),
      m_ignore_incoming_txs(ignore_incoming_txs)
{
}

void PeerManagerImpl::StartScheduledTasks(CScheduler& scheduler)
{
    // Stale tip checking and peer eviction are on two different timers, but we
    // don't want them to get out of sync due to drift in the scheduler, so we
    // combine them in one function and schedule at the quicker (peer-eviction)
    // timer.
    static_assert(EXTRA_PEER_CHECK_INTERVAL < STALE_CHECK_INTERVAL, "peer eviction timer should be less than stale tip check timer");
    scheduler.scheduleEvery([this] { this->CheckForStaleTipAndEvictPeers(); }, std::chrono::seconds{EXTRA_PEER_CHECK_INTERVAL});

    // schedule next run for 10-15 minutes in the future
    const std::chrono::milliseconds delta = std::chrono::minutes{10} + GetRandMillis(std::chrono::minutes{5});
    scheduler.scheduleFromNow([&] { ReattemptInitialBroadcast(scheduler); }, delta);
}

/**
 * Evict orphan txn pool entries based on a newly connected
 * block, remember the recently confirmed transactions, and delete tracked
 * announcements for them. Also save the time of the last tip update.
 */
void PeerManagerImpl::BlockConnected(const std::shared_ptr<const CBlock>& pblock, const CBlockIndex* pindex)
{
    m_orphanage.EraseForBlock(*pblock);
    m_last_tip_update = GetTime();

    {
        LOCK(m_recent_confirmed_transactions_mutex);
        for (const auto& ptx : pblock->vtx) {
            m_recent_confirmed_transactions.insert(ptx->GetHash());
            if (ptx->GetHash() != ptx->GetWitnessHash()) {
                m_recent_confirmed_transactions.insert(ptx->GetWitnessHash());
            }
        }
    }
    {
        LOCK(cs_main);
        for (const auto& ptx : pblock->vtx) {
            m_txrequest.ForgetTxHash(ptx->GetHash());
            m_txrequest.ForgetTxHash(ptx->GetWitnessHash());
        }
    }
}

void PeerManagerImpl::BlockDisconnected(const std::shared_ptr<const CBlock> &block, const CBlockIndex* pindex)
{
    // To avoid relay problems with transactions that were previously
    // confirmed, clear our filter of recently confirmed transactions whenever
    // there's a reorg.
    // This means that in a 1-block reorg (where 1 block is disconnected and
    // then another block reconnected), our filter will drop to having only one
    // block's worth of transactions in it, but that should be fine, since
    // presumably the most common case of relaying a confirmed transaction
    // should be just after a new block containing it is found.
    LOCK(m_recent_confirmed_transactions_mutex);
    m_recent_confirmed_transactions.reset();
}

// All of the following cache a recent block, and are protected by cs_most_recent_block
static RecursiveMutex cs_most_recent_block;
static std::shared_ptr<const CBlock> most_recent_block GUARDED_BY(cs_most_recent_block);
static std::shared_ptr<const CBlockHeaderAndShortTxIDs> most_recent_compact_block GUARDED_BY(cs_most_recent_block);
static uint256 most_recent_block_hash GUARDED_BY(cs_most_recent_block);
static bool fWitnessesPresentInMostRecentCompactBlock GUARDED_BY(cs_most_recent_block);

/**
 * Maintain state about the best-seen block and fast-announce a compact block
 * to compatible peers.
 */
void PeerManagerImpl::NewPoWValidBlock(const CBlockIndex *pindex, const std::shared_ptr<const CBlock>& pblock)
{
    std::shared_ptr<const CBlockHeaderAndShortTxIDs> pcmpctblock = std::make_shared<const CBlockHeaderAndShortTxIDs> (*pblock, true);
    const CNetMsgMaker msgMaker(PROTOCOL_VERSION);

    LOCK(cs_main);

    static int nHighestFastAnnounce = 0;
    if (pindex->nHeight <= nHighestFastAnnounce)
        return;
    nHighestFastAnnounce = pindex->nHeight;

    bool fWitnessEnabled = DeploymentActiveAt(*pindex, m_chainparams.GetConsensus(), Consensus::DEPLOYMENT_SEGWIT);
    uint256 hashBlock(pblock->GetHash());

    {
        LOCK(cs_most_recent_block);
        most_recent_block_hash = hashBlock;
        most_recent_block = pblock;
        most_recent_compact_block = pcmpctblock;
        fWitnessesPresentInMostRecentCompactBlock = fWitnessEnabled;
    }

    m_connman.ForEachNode([this, &pcmpctblock, pindex, &msgMaker, fWitnessEnabled, &hashBlock](CNode* pnode) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
        AssertLockHeld(::cs_main);

        // TODO: Avoid the repeated-serialization here
        if (pnode->GetCommonVersion() < INVALID_CB_NO_BAN_VERSION || pnode->fDisconnect)
            return;
        ProcessBlockAvailability(pnode->GetId());
        CNodeState &state = *State(pnode->GetId());
        // If the peer has, or we announced to them the previous block already,
        // but we don't think they have this one, go ahead and announce it
        if (state.fPreferHeaderAndIDs && (!fWitnessEnabled || state.fWantsCmpctWitness) &&
                !PeerHasHeader(&state, pindex) && PeerHasHeader(&state, pindex->pprev)) {

            LogPrint(BCLog::NET, "%s sending header-and-ids %s to peer=%d\n", "PeerManager::NewPoWValidBlock",
                    hashBlock.ToString(), pnode->GetId());
            m_connman.PushMessage(pnode, msgMaker.Make(NetMsgType::CMPCTBLOCK, *pcmpctblock));
            state.pindexBestHeaderSent = pindex;
        }
    });
}

/**
 * Update our best height and announce any block hashes which weren't previously
 * in m_chainman.ActiveChain() to our peers.
 */
void PeerManagerImpl::UpdatedBlockTip(const CBlockIndex *pindexNew, const CBlockIndex *pindexFork, bool fInitialDownload)
{
    SetBestHeight(pindexNew->nHeight);
    SetServiceFlagsIBDCache(!fInitialDownload);

    // Don't relay inventory during initial block download.
    if (fInitialDownload) return;

    // Find the hashes of all blocks that weren't previously in the best chain.
    std::vector<uint256> vHashes;
    const CBlockIndex *pindexToAnnounce = pindexNew;
    while (pindexToAnnounce != pindexFork) {
        vHashes.push_back(pindexToAnnounce->GetBlockHash());
        pindexToAnnounce = pindexToAnnounce->pprev;
        if (vHashes.size() == MAX_BLOCKS_TO_ANNOUNCE) {
            // Limit announcements in case of a huge reorganization.
            // Rely on the peer's synchronization mechanism in that case.
            break;
        }
    }

    {
        LOCK(m_peer_mutex);
        for (auto& it : m_peer_map) {
            Peer& peer = *it.second;
            LOCK(peer.m_block_inv_mutex);
            for (const uint256& hash : reverse_iterate(vHashes)) {
                peer.m_blocks_for_headers_relay.push_back(hash);
            }
        }
    }

    m_connman.WakeMessageHandler();
}

/**
 * Handle invalid block rejection and consequent peer discouragement, maintain which
 * peers announce compact blocks.
 */
void PeerManagerImpl::BlockChecked(const CBlock& block, const BlockValidationState& state)
{
    LOCK(cs_main);

    const uint256 hash(block.GetHash());
    std::map<uint256, std::pair<NodeId, bool>>::iterator it = mapBlockSource.find(hash);

    // If the block failed validation, we know where it came from and we're still connected
    // to that peer, maybe punish.
    if (state.IsInvalid() &&
        it != mapBlockSource.end() &&
        State(it->second.first)) {
            MaybePunishNodeForBlock(/*nodeid=*/ it->second.first, state, /*via_compact_block=*/ !it->second.second);
    }
    // Check that:
    // 1. The block is valid
    // 2. We're not in initial block download
    // 3. This is currently the best block we're aware of. We haven't updated
    //    the tip yet so we have no way to check this directly here. Instead we
    //    just check that there are currently no other blocks in flight.
    else if (state.IsValid() &&
             !m_chainman.ActiveChainstate().IsInitialBlockDownload() &&
             mapBlocksInFlight.count(hash) == mapBlocksInFlight.size()) {
        if (it != mapBlockSource.end()) {
            MaybeSetPeerAsAnnouncingHeaderAndIDs(it->second.first);
        }
    }
    if (it != mapBlockSource.end())
        mapBlockSource.erase(it);
}

//////////////////////////////////////////////////////////////////////////////
//
// Messages
//


bool PeerManagerImpl::AlreadyHaveTx(const GenTxid& gtxid)
{
    if (m_chainman.ActiveChain().Tip()->GetBlockHash() != hashRecentRejectsChainTip) {
        // If the chain tip has changed previously rejected transactions
        // might be now valid, e.g. due to a nLockTime'd tx becoming valid,
        // or a double-spend. Reset the rejects filter and give those
        // txs a second chance.
        hashRecentRejectsChainTip = m_chainman.ActiveChain().Tip()->GetBlockHash();
        m_recent_rejects.reset();
    }

    const uint256& hash = gtxid.GetHash();

    if (m_orphanage.HaveTx(gtxid)) return true;

    {
        LOCK(m_recent_confirmed_transactions_mutex);
        if (m_recent_confirmed_transactions.contains(hash)) return true;
    }

    return m_recent_rejects.contains(hash) || m_mempool.exists(gtxid);
}

bool PeerManagerImpl::AlreadyHaveBlock(const uint256& block_hash)
{
    return m_chainman.m_blockman.LookupBlockIndex(block_hash) != nullptr;
}

void PeerManagerImpl::SendPings()
{
    LOCK(m_peer_mutex);
    for(auto& it : m_peer_map) it.second->m_ping_queued = true;
}

void PeerManagerImpl::RelayTransaction(const uint256& txid, const uint256& wtxid)
{
    WITH_LOCK(cs_main, _RelayTransaction(txid, wtxid););
}

void PeerManagerImpl::_RelayTransaction(const uint256& txid, const uint256& wtxid)
{
    m_connman.ForEachNode([&txid, &wtxid](CNode* pnode) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
        AssertLockHeld(::cs_main);

        CNodeState* state = State(pnode->GetId());
        if (state == nullptr) return;
        if (state->m_wtxid_relay) {
            pnode->PushTxInventory(wtxid);
        } else {
            pnode->PushTxInventory(txid);
        }
    });
}

void PeerManagerImpl::RelayAddress(NodeId originator,
                                   const CAddress& addr,
                                   bool fReachable)
{
    // We choose the same nodes within a given 24h window (if the list of connected
    // nodes does not change) and we don't relay to nodes that already know an
    // address. So within 24h we will likely relay a given address once. This is to
    // prevent a peer from unjustly giving their address better propagation by sending
    // it to us repeatedly.

    if (!fReachable && !addr.IsRelayable()) return;

    // Relay to a limited number of other nodes
    // Use deterministic randomness to send to the same nodes for 24 hours
    // at a time so the m_addr_knowns of the chosen nodes prevent repeats
    uint64_t hashAddr = addr.GetHash();
    const CSipHasher hasher = m_connman.GetDeterministicRandomizer(RANDOMIZER_ID_ADDRESS_RELAY).Write(hashAddr << 32).Write((GetTime() + hashAddr) / (24 * 60 * 60));
    FastRandomContext insecure_rand;

    // Relay reachable addresses to 2 peers. Unreachable addresses are relayed randomly to 1 or 2 peers.
    unsigned int nRelayNodes = (fReachable || (hasher.Finalize() & 1)) ? 2 : 1;

    std::array<std::pair<uint64_t, Peer*>, 2> best{{{0, nullptr}, {0, nullptr}}};
    assert(nRelayNodes <= best.size());

    LOCK(m_peer_mutex);

    for (auto& [id, peer] : m_peer_map) {
        if (peer->m_addr_relay_enabled && id != originator && IsAddrCompatible(*peer, addr)) {
            uint64_t hashKey = CSipHasher(hasher).Write(id).Finalize();
            for (unsigned int i = 0; i < nRelayNodes; i++) {
                 if (hashKey > best[i].first) {
                     std::copy(best.begin() + i, best.begin() + nRelayNodes - 1, best.begin() + i + 1);
                     best[i] = std::make_pair(hashKey, peer.get());
                     break;
                 }
            }
        }
    };

    for (unsigned int i = 0; i < nRelayNodes && best[i].first != 0; i++) {
        PushAddress(*best[i].second, addr, insecure_rand);
    }
}

void PeerManagerImpl::ProcessGetBlockData(CNode& pfrom, Peer& peer, const CInv& inv)
{
    std::shared_ptr<const CBlock> a_recent_block;
    std::shared_ptr<const CBlockHeaderAndShortTxIDs> a_recent_compact_block;
    bool fWitnessesPresentInARecentCompactBlock;
    {
        LOCK(cs_most_recent_block);
        a_recent_block = most_recent_block;
        a_recent_compact_block = most_recent_compact_block;
        fWitnessesPresentInARecentCompactBlock = fWitnessesPresentInMostRecentCompactBlock;
    }

    bool need_activate_chain = false;
    {
        LOCK(cs_main);
        const CBlockIndex* pindex = m_chainman.m_blockman.LookupBlockIndex(inv.hash);
        if (pindex) {
            if (pindex->HaveTxsDownloaded() && !pindex->IsValid(BLOCK_VALID_SCRIPTS) &&
                    pindex->IsValid(BLOCK_VALID_TREE)) {
                // If we have the block and all of its parents, but have not yet validated it,
                // we might be in the middle of connecting it (ie in the unlock of cs_main
                // before ActivateBestChain but after AcceptBlock).
                // In this case, we need to run ActivateBestChain prior to checking the relay
                // conditions below.
                need_activate_chain = true;
            }
        }
    } // release cs_main before calling ActivateBestChain
    if (need_activate_chain) {
        BlockValidationState state;
        if (!m_chainman.ActiveChainstate().ActivateBestChain(state, a_recent_block)) {
            LogPrint(BCLog::NET, "failed to activate chain (%s)\n", state.ToString());
        }
    }

    LOCK(cs_main);
    const CBlockIndex* pindex = m_chainman.m_blockman.LookupBlockIndex(inv.hash);
    if (!pindex) {
        return;
    }
    if (!BlockRequestAllowed(pindex)) {
        LogPrint(BCLog::NET, "%s: ignoring request from peer=%i for old block that isn't in the main chain\n", __func__, pfrom.GetId());
        return;
    }
    const CNetMsgMaker msgMaker(pfrom.GetCommonVersion());
    // disconnect node in case we have reached the outbound limit for serving historical blocks
    if (m_connman.OutboundTargetReached(true) &&
        (((pindexBestHeader != nullptr) && (pindexBestHeader->GetBlockTime() - pindex->GetBlockTime() > HISTORICAL_BLOCK_AGE)) || inv.IsMsgFilteredBlk()) &&
        !pfrom.HasPermission(NetPermissionFlags::Download) // nodes with the download permission may exceed target
    ) {
        LogPrint(BCLog::NET, "historical block serving limit reached, disconnect peer=%d\n", pfrom.GetId());
        pfrom.fDisconnect = true;
        return;
    }
    // Avoid leaking prune-height by never sending blocks below the NODE_NETWORK_LIMITED threshold
    if (!pfrom.HasPermission(NetPermissionFlags::NoBan) && (
            (((pfrom.GetLocalServices() & NODE_NETWORK_LIMITED) == NODE_NETWORK_LIMITED) && ((pfrom.GetLocalServices() & NODE_NETWORK) != NODE_NETWORK) && (m_chainman.ActiveChain().Tip()->nHeight - pindex->nHeight > (int)NODE_NETWORK_LIMITED_MIN_BLOCKS + 2 /* add two blocks buffer extension for possible races */) )
       )) {
        LogPrint(BCLog::NET, "Ignore block request below NODE_NETWORK_LIMITED threshold, disconnect peer=%d\n", pfrom.GetId());
        //disconnect node and prevent it from stalling (would otherwise wait for the missing block)
        pfrom.fDisconnect = true;
        return;
    }
    // Pruned nodes may have deleted the block, so check whether
    // it's available before trying to send.
    if (!(pindex->nStatus & BLOCK_HAVE_DATA)) {
        return;
    }
    std::shared_ptr<const CBlock> pblock;
    if (a_recent_block && a_recent_block->GetHash() == pindex->GetBlockHash()) {
        pblock = a_recent_block;
    } else if (inv.IsMsgWitnessBlk()) {
        // Fast-path: in this case it is possible to serve the block directly from disk,
        // as the network format matches the format on disk
        std::vector<uint8_t> block_data;
        if (!ReadRawBlockFromDisk(block_data, pindex, m_chainparams.MessageStart())) {
            assert(!"cannot load block from disk");
        }
        m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::BLOCK, MakeSpan(block_data)));
        // Don't set pblock as we've sent the block
    } else {
        // Send block from disk
        std::shared_ptr<CBlock> pblockRead = std::make_shared<CBlock>();
        if (!ReadBlockFromDisk(*pblockRead, pindex, m_chainparams.GetConsensus())) {
            assert(!"cannot load block from disk");
        }
        pblock = pblockRead;
    }
    if (pblock) {
        if (inv.IsMsgBlk()) {
            m_connman.PushMessage(&pfrom, msgMaker.Make(SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::BLOCK, *pblock));
        } else if (inv.IsMsgWitnessBlk()) {
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::BLOCK, *pblock));
        } else if (inv.IsMsgFilteredBlk()) {
            bool sendMerkleBlock = false;
            CMerkleBlock merkleBlock;
            if (pfrom.m_tx_relay != nullptr) {
                LOCK(pfrom.m_tx_relay->cs_filter);
                if (pfrom.m_tx_relay->pfilter) {
                    sendMerkleBlock = true;
                    merkleBlock = CMerkleBlock(*pblock, *pfrom.m_tx_relay->pfilter);
                }
            }
            if (sendMerkleBlock) {
                m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::MERKLEBLOCK, merkleBlock));
                // CMerkleBlock just contains hashes, so also push any transactions in the block the client did not see
                // This avoids hurting performance by pointlessly requiring a round-trip
                // Note that there is currently no way for a node to request any single transactions we didn't send here -
                // they must either disconnect and retry or request the full block.
                // Thus, the protocol spec specified allows for us to provide duplicate txn here,
                // however we MUST always provide at least what the remote peer needs
                typedef std::pair<unsigned int, uint256> PairType;
                for (PairType& pair : merkleBlock.vMatchedTxn)
                    m_connman.PushMessage(&pfrom, msgMaker.Make(SERIALIZE_TRANSACTION_NO_WITNESS, NetMsgType::TX, *pblock->vtx[pair.first]));
            }
            // else
            // no response
        } else if (inv.IsMsgCmpctBlk()) {
            // If a peer is asking for old blocks, we're almost guaranteed
            // they won't have a useful mempool to match against a compact block,
            // and we don't feel like constructing the object for them, so
            // instead we respond with the full, non-compact block.
            bool fPeerWantsWitness = State(pfrom.GetId())->fWantsCmpctWitness;
            int nSendFlags = fPeerWantsWitness ? 0 : SERIALIZE_TRANSACTION_NO_WITNESS;
            if (CanDirectFetch() && pindex->nHeight >= m_chainman.ActiveChain().Height() - MAX_CMPCTBLOCK_DEPTH) {
                if ((fPeerWantsWitness || !fWitnessesPresentInARecentCompactBlock) && a_recent_compact_block && a_recent_compact_block->header.GetHash() == pindex->GetBlockHash()) {
                    m_connman.PushMessage(&pfrom, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, *a_recent_compact_block));
                } else {
                    CBlockHeaderAndShortTxIDs cmpctblock(*pblock, fPeerWantsWitness);
                    m_connman.PushMessage(&pfrom, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, cmpctblock));
                }
            } else {
                m_connman.PushMessage(&pfrom, msgMaker.Make(nSendFlags, NetMsgType::BLOCK, *pblock));
            }
        }
    }

    {
        LOCK(peer.m_block_inv_mutex);
        // Trigger the peer node to send a getblocks request for the next batch of inventory
        if (inv.hash == peer.m_continuation_block) {
            // Send immediately. This must send even if redundant,
            // and we want it right after the last block so they don't
            // wait for other stuff first.
            std::vector<CInv> vInv;
            vInv.push_back(CInv(MSG_BLOCK, m_chainman.ActiveChain().Tip()->GetBlockHash()));
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::INV, vInv));
            peer.m_continuation_block.SetNull();
        }
    }
}

CTransactionRef PeerManagerImpl::FindTxForGetData(const CNode& peer, const GenTxid& gtxid, const std::chrono::seconds mempool_req, const std::chrono::seconds now)
{
    auto txinfo = m_mempool.info(gtxid);
    if (txinfo.tx) {
        // If a TX could have been INVed in reply to a MEMPOOL request,
        // or is older than UNCONDITIONAL_RELAY_DELAY, permit the request
        // unconditionally.
        if ((mempool_req.count() && txinfo.m_time <= mempool_req) || txinfo.m_time <= now - UNCONDITIONAL_RELAY_DELAY) {
            return std::move(txinfo.tx);
        }
    }

    {
        LOCK(cs_main);
        // Otherwise, the transaction must have been announced recently.
        if (State(peer.GetId())->m_recently_announced_invs.contains(gtxid.GetHash())) {
            // If it was, it can be relayed from either the mempool...
            if (txinfo.tx) return std::move(txinfo.tx);
            // ... or the relay pool.
            auto mi = mapRelay.find(gtxid.GetHash());
            if (mi != mapRelay.end()) return mi->second;
        }
    }

    return {};
}

void PeerManagerImpl::ProcessGetData(CNode& pfrom, Peer& peer, const std::atomic<bool>& interruptMsgProc)
{
    AssertLockNotHeld(cs_main);

    std::deque<CInv>::iterator it = peer.m_getdata_requests.begin();
    std::vector<CInv> vNotFound;
    const CNetMsgMaker msgMaker(pfrom.GetCommonVersion());

    const std::chrono::seconds now = GetTime<std::chrono::seconds>();
    // Get last mempool request time
    const std::chrono::seconds mempool_req = pfrom.m_tx_relay != nullptr ? pfrom.m_tx_relay->m_last_mempool_req.load()
                                                                          : std::chrono::seconds::min();

    // Process as many TX items from the front of the getdata queue as
    // possible, since they're common and it's efficient to batch process
    // them.
    while (it != peer.m_getdata_requests.end() && it->IsGenTxMsg()) {
        if (interruptMsgProc) return;
        // The send buffer provides backpressure. If there's no space in
        // the buffer, pause processing until the next call.
        if (pfrom.fPauseSend) break;

        const CInv &inv = *it++;

        if (pfrom.m_tx_relay == nullptr) {
            // Ignore GETDATA requests for transactions from blocks-only peers.
            continue;
        }

        CTransactionRef tx = FindTxForGetData(pfrom, ToGenTxid(inv), mempool_req, now);
        if (tx) {
            // WTX and WITNESS_TX imply we serialize with witness
            int nSendFlags = (inv.IsMsgTx() ? SERIALIZE_TRANSACTION_NO_WITNESS : 0);
            m_connman.PushMessage(&pfrom, msgMaker.Make(nSendFlags, NetMsgType::TX, *tx));
            m_mempool.RemoveUnbroadcastTx(tx->GetHash());
            // As we're going to send tx, make sure its unconfirmed parents are made requestable.
            std::vector<uint256> parent_ids_to_add;
            {
                LOCK(m_mempool.cs);
                auto txiter = m_mempool.GetIter(tx->GetHash());
                if (txiter) {
                    const CTxMemPoolEntry::Parents& parents = (*txiter)->GetMemPoolParentsConst();
                    parent_ids_to_add.reserve(parents.size());
                    for (const CTxMemPoolEntry& parent : parents) {
                        if (parent.GetTime() > now - UNCONDITIONAL_RELAY_DELAY) {
                            parent_ids_to_add.push_back(parent.GetTx().GetHash());
                        }
                    }
                }
            }
            for (const uint256& parent_txid : parent_ids_to_add) {
                // Relaying a transaction with a recent but unconfirmed parent.
                if (WITH_LOCK(pfrom.m_tx_relay->cs_tx_inventory, return !pfrom.m_tx_relay->filterInventoryKnown.contains(parent_txid))) {
                    LOCK(cs_main);
                    State(pfrom.GetId())->m_recently_announced_invs.insert(parent_txid);
                }
            }
        } else {
            vNotFound.push_back(inv);
        }
    }

    // Only process one BLOCK item per call, since they're uncommon and can be
    // expensive to process.
    if (it != peer.m_getdata_requests.end() && !pfrom.fPauseSend) {
        const CInv &inv = *it++;
        if (inv.IsGenBlkMsg()) {
            ProcessGetBlockData(pfrom, peer, inv);
        }
        // else: If the first item on the queue is an unknown type, we erase it
        // and continue processing the queue on the next call.
    }

    peer.m_getdata_requests.erase(peer.m_getdata_requests.begin(), it);

    if (!vNotFound.empty()) {
        // Let the peer know that we didn't find what it asked for, so it doesn't
        // have to wait around forever.
        // SPV clients care about this message: it's needed when they are
        // recursively walking the dependencies of relevant unconfirmed
        // transactions. SPV clients want to do that because they want to know
        // about (and store and rebroadcast and risk analyze) the dependencies
        // of transactions relevant to them, without having to download the
        // entire memory pool.
        // Also, other nodes can use these messages to automatically request a
        // transaction from some other peer that annnounced it, and stop
        // waiting for us to respond.
        // In normal operation, we often send NOTFOUND messages for parents of
        // transactions that we relay; if a peer is missing a parent, they may
        // assume we have them and request the parents from us.
        m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::NOTFOUND, vNotFound));
    }
}

static uint32_t GetFetchFlags(const CNode& pfrom) EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
    uint32_t nFetchFlags = 0;
    if (State(pfrom.GetId())->fHaveWitness) {
        nFetchFlags |= MSG_WITNESS_FLAG;
    }
    return nFetchFlags;
}

void PeerManagerImpl::SendBlockTransactions(CNode& pfrom, const CBlock& block, const BlockTransactionsRequest& req)
{
    BlockTransactions resp(req);
    for (size_t i = 0; i < req.indexes.size(); i++) {
        if (req.indexes[i] >= block.vtx.size()) {
            Misbehaving(pfrom.GetId(), 100, "getblocktxn with out-of-bounds tx indices");
            return;
        }
        resp.txn[i] = block.vtx[req.indexes[i]];
    }
    LOCK(cs_main);
    const CNetMsgMaker msgMaker(pfrom.GetCommonVersion());
    int nSendFlags = State(pfrom.GetId())->fWantsCmpctWitness ? 0 : SERIALIZE_TRANSACTION_NO_WITNESS;
    m_connman.PushMessage(&pfrom, msgMaker.Make(nSendFlags, NetMsgType::BLOCKTXN, resp));
}

void PeerManagerImpl::ProcessHeadersMessage(CNode& pfrom, const Peer& peer,
                                            const std::vector<CBlockHeader>& headers,
                                            bool via_compact_block)
{
    const CNetMsgMaker msgMaker(pfrom.GetCommonVersion());
    size_t nCount = headers.size();

    if (nCount == 0) {
        // Nothing interesting. Stop asking this peers for more headers.
        return;
    }

    bool received_new_header = false;
    const CBlockIndex *pindexLast = nullptr;
    {
        LOCK(cs_main);
        CNodeState *nodestate = State(pfrom.GetId());

        // If this looks like it could be a block announcement (nCount <
        // MAX_BLOCKS_TO_ANNOUNCE), use special logic for handling headers that
        // don't connect:
        // - Send a getheaders message in response to try to connect the chain.
        // - The peer can send up to MAX_UNCONNECTING_HEADERS in a row that
        //   don't connect before giving DoS points
        // - Once a headers message is received that is valid and does connect,
        //   nUnconnectingHeaders gets reset back to 0.
        if (!m_chainman.m_blockman.LookupBlockIndex(headers[0].hashPrevBlock) && nCount < MAX_BLOCKS_TO_ANNOUNCE) {
            nodestate->nUnconnectingHeaders++;
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETHEADERS, m_chainman.ActiveChain().GetLocator(pindexBestHeader), uint256()));
            LogPrint(BCLog::NET, "received header %s: missing prev block %s, sending getheaders (%d) to end (peer=%d, nUnconnectingHeaders=%d)\n",
                    headers[0].GetHash().ToString(),
                    headers[0].hashPrevBlock.ToString(),
                    pindexBestHeader->nHeight,
                    pfrom.GetId(), nodestate->nUnconnectingHeaders);
            // Set hashLastUnknownBlock for this peer, so that if we
            // eventually get the headers - even from a different peer -
            // we can use this peer to download.
            UpdateBlockAvailability(pfrom.GetId(), headers.back().GetHash());

            if (nodestate->nUnconnectingHeaders % MAX_UNCONNECTING_HEADERS == 0) {
                Misbehaving(pfrom.GetId(), 20, strprintf("%d non-connecting headers", nodestate->nUnconnectingHeaders));
            }
            return;
        }

        uint256 hashLastBlock;
        for (const CBlockHeader& header : headers) {
            if (!hashLastBlock.IsNull() && header.hashPrevBlock != hashLastBlock) {
                Misbehaving(pfrom.GetId(), 20, "non-continuous headers sequence");
                return;
            }
            hashLastBlock = header.GetHash();
        }

        // If we don't have the last header, then they'll have given us
        // something new (if these headers are valid).
        if (!m_chainman.m_blockman.LookupBlockIndex(hashLastBlock)) {
            received_new_header = true;
        }
    }

    BlockValidationState state;
    if (!m_chainman.ProcessNewBlockHeaders(headers, state, m_chainparams, &pindexLast)) {
        if (state.IsInvalid()) {
            MaybePunishNodeForBlock(pfrom.GetId(), state, via_compact_block, "invalid header received");
            return;
        }
    }

    {
        LOCK(cs_main);
        CNodeState *nodestate = State(pfrom.GetId());
        if (nodestate->nUnconnectingHeaders > 0) {
            LogPrint(BCLog::NET, "peer=%d: resetting nUnconnectingHeaders (%d -> 0)\n", pfrom.GetId(), nodestate->nUnconnectingHeaders);
        }
        nodestate->nUnconnectingHeaders = 0;

        assert(pindexLast);
        UpdateBlockAvailability(pfrom.GetId(), pindexLast->GetBlockHash());

        // From here, pindexBestKnownBlock should be guaranteed to be non-null,
        // because it is set in UpdateBlockAvailability. Some nullptr checks
        // are still present, however, as belt-and-suspenders.

        if (received_new_header && pindexLast->nChainWork > m_chainman.ActiveChain().Tip()->nChainWork) {
            nodestate->m_last_block_announcement = GetTime();
        }

        if (nCount == MAX_HEADERS_RESULTS) {
            // Headers message had its maximum size; the peer may have more headers.
            // TODO: optimize: if pindexLast is an ancestor of m_chainman.ActiveChain().Tip or pindexBestHeader, continue
            // from there instead.
            LogPrint(BCLog::NET, "more getheaders (%d) to end to peer=%d (startheight:%d)\n",
                                 pindexLast->nHeight, pfrom.GetId(), peer.m_starting_height);
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETHEADERS, m_chainman.ActiveChain().GetLocator(pindexLast), uint256()));
        }

        // If this set of headers is valid and ends in a block with at least as
        // much work as our tip, download as much as possible.
        if (CanDirectFetch() && pindexLast->IsValid(BLOCK_VALID_TREE) && m_chainman.ActiveChain().Tip()->nChainWork <= pindexLast->nChainWork) {
            std::vector<const CBlockIndex*> vToFetch;
            const CBlockIndex *pindexWalk = pindexLast;
            // Calculate all the blocks we'd need to switch to pindexLast, up to a limit.
            while (pindexWalk && !m_chainman.ActiveChain().Contains(pindexWalk) && vToFetch.size() <= MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
                if (!(pindexWalk->nStatus & BLOCK_HAVE_DATA) &&
                        !IsBlockRequested(pindexWalk->GetBlockHash()) &&
                        (!DeploymentActiveAt(*pindexWalk, m_chainparams.GetConsensus(), Consensus::DEPLOYMENT_SEGWIT) || State(pfrom.GetId())->fHaveWitness)) {
                    // We don't have this block, and it's not yet in flight.
                    vToFetch.push_back(pindexWalk);
                }
                pindexWalk = pindexWalk->pprev;
            }
            // If pindexWalk still isn't on our main chain, we're looking at a
            // very large reorg at a time we think we're close to caught up to
            // the main chain -- this shouldn't really happen.  Bail out on the
            // direct fetch and rely on parallel download instead.
            if (!m_chainman.ActiveChain().Contains(pindexWalk)) {
                LogPrint(BCLog::NET, "Large reorg, won't direct fetch to %s (%d)\n",
                        pindexLast->GetBlockHash().ToString(),
                        pindexLast->nHeight);
            } else {
                std::vector<CInv> vGetData;
                // Download as much as possible, from earliest to latest.
                for (const CBlockIndex *pindex : reverse_iterate(vToFetch)) {
                    if (nodestate->nBlocksInFlight >= MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
                        // Can't download any more from this peer
                        break;
                    }
                    uint32_t nFetchFlags = GetFetchFlags(pfrom);
                    vGetData.push_back(CInv(MSG_BLOCK | nFetchFlags, pindex->GetBlockHash()));
                    BlockRequested(pfrom.GetId(), *pindex);
                    LogPrint(BCLog::NET, "Requesting block %s from  peer=%d\n",
                            pindex->GetBlockHash().ToString(), pfrom.GetId());
                }
                if (vGetData.size() > 1) {
                    LogPrint(BCLog::NET, "Downloading blocks toward %s (%d) via headers direct fetch\n",
                            pindexLast->GetBlockHash().ToString(), pindexLast->nHeight);
                }
                if (vGetData.size() > 0) {
                    if (nodestate->fSupportsDesiredCmpctVersion && vGetData.size() == 1 && mapBlocksInFlight.size() == 1 && pindexLast->pprev->IsValid(BLOCK_VALID_CHAIN)) {
                        // In any case, we want to download using a compact block, not a regular one
                        vGetData[0] = CInv(MSG_CMPCT_BLOCK, vGetData[0].hash);
                    }
                    m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETDATA, vGetData));
                }
            }
        }
        // If we're in IBD, we want outbound peers that will serve us a useful
        // chain. Disconnect peers that are on chains with insufficient work.
        if (m_chainman.ActiveChainstate().IsInitialBlockDownload() && nCount != MAX_HEADERS_RESULTS) {
            // When nCount < MAX_HEADERS_RESULTS, we know we have no more
            // headers to fetch from this peer.
            if (nodestate->pindexBestKnownBlock && nodestate->pindexBestKnownBlock->nChainWork < nMinimumChainWork) {
                // This peer has too little work on their headers chain to help
                // us sync -- disconnect if it is an outbound disconnection
                // candidate.
                // Note: We compare their tip to nMinimumChainWork (rather than
                // m_chainman.ActiveChain().Tip()) because we won't start block download
                // until we have a headers chain that has at least
                // nMinimumChainWork, even if a peer has a chain past our tip,
                // as an anti-DoS measure.
                if (pfrom.IsOutboundOrBlockRelayConn()) {
                    LogPrintf("Disconnecting outbound peer %d -- headers chain has insufficient work\n", pfrom.GetId());
                    pfrom.fDisconnect = true;
                }
            }
        }

        // If this is an outbound full-relay peer, check to see if we should protect
        // it from the bad/lagging chain logic.
        // Note that outbound block-relay peers are excluded from this protection, and
        // thus always subject to eviction under the bad/lagging chain logic.
        // See ChainSyncTimeoutState.
        if (!pfrom.fDisconnect && pfrom.IsFullOutboundConn() && nodestate->pindexBestKnownBlock != nullptr) {
            if (m_outbound_peers_with_protect_from_disconnect < MAX_OUTBOUND_PEERS_TO_PROTECT_FROM_DISCONNECT && nodestate->pindexBestKnownBlock->nChainWork >= m_chainman.ActiveChain().Tip()->nChainWork && !nodestate->m_chain_sync.m_protect) {
                LogPrint(BCLog::NET, "Protecting outbound peer=%d from eviction\n", pfrom.GetId());
                nodestate->m_chain_sync.m_protect = true;
                ++m_outbound_peers_with_protect_from_disconnect;
            }
        }
    }

    return;
}

/**
 * Reconsider orphan transactions after a parent has been accepted to the mempool.
 *
 * @param[in,out]  orphan_work_set  The set of orphan transactions to reconsider. Generally only one
 *                                  orphan will be reconsidered on each call of this function. This set
 *                                  may be added to if accepting an orphan causes its children to be
 *                                  reconsidered.
 */
void PeerManagerImpl::ProcessOrphanTx(std::set<uint256>& orphan_work_set)
{
    AssertLockHeld(cs_main);
    AssertLockHeld(g_cs_orphans);

    while (!orphan_work_set.empty()) {
        const uint256 orphanHash = *orphan_work_set.begin();
        orphan_work_set.erase(orphan_work_set.begin());

        const auto [porphanTx, from_peer] = m_orphanage.GetTx(orphanHash);
        if (porphanTx == nullptr) continue;

        const MempoolAcceptResult result = AcceptToMemoryPool(m_chainman.ActiveChainstate(), m_mempool, porphanTx, false /* bypass_limits */);
        const TxValidationState& state = result.m_state;

        if (result.m_result_type == MempoolAcceptResult::ResultType::VALID) {
            LogPrint(BCLog::MEMPOOL, "   accepted orphan tx %s\n", orphanHash.ToString());
            _RelayTransaction(orphanHash, porphanTx->GetWitnessHash());
            m_orphanage.AddChildrenToWorkSet(*porphanTx, orphan_work_set);
            m_orphanage.EraseTx(orphanHash);
            for (const CTransactionRef& removedTx : result.m_replaced_transactions.value()) {
                AddToCompactExtraTransactions(removedTx);
            }
            break;
        } else if (state.GetResult() != TxValidationResult::TX_MISSING_INPUTS) {
            if (state.IsInvalid()) {
                LogPrint(BCLog::MEMPOOL, "   invalid orphan tx %s from peer=%d. %s\n",
                    orphanHash.ToString(),
                    from_peer,
                    state.ToString());
                // Maybe punish peer that gave us an invalid orphan tx
                MaybePunishNodeForTx(from_peer, state);
            }
            // Has inputs but not accepted to mempool
            // Probably non-standard or insufficient fee
            LogPrint(BCLog::MEMPOOL, "   removed orphan tx %s\n", orphanHash.ToString());
            if (state.GetResult() != TxValidationResult::TX_WITNESS_STRIPPED) {
                // We can add the wtxid of this transaction to our reject filter.
                // Do not add txids of witness transactions or witness-stripped
                // transactions to the filter, as they can have been malleated;
                // adding such txids to the reject filter would potentially
                // interfere with relay of valid transactions from peers that
                // do not support wtxid-based relay. See
                // https://github.com/bitcoin/bitcoin/issues/8279 for details.
                // We can remove this restriction (and always add wtxids to
                // the filter even for witness stripped transactions) once
                // wtxid-based relay is broadly deployed.
                // See also comments in https://github.com/bitcoin/bitcoin/pull/18044#discussion_r443419034
                // for concerns around weakening security of unupgraded nodes
                // if we start doing this too early.
                m_recent_rejects.insert(porphanTx->GetWitnessHash());
                // If the transaction failed for TX_INPUTS_NOT_STANDARD,
                // then we know that the witness was irrelevant to the policy
                // failure, since this check depends only on the txid
                // (the scriptPubKey being spent is covered by the txid).
                // Add the txid to the reject filter to prevent repeated
                // processing of this transaction in the event that child
                // transactions are later received (resulting in
                // parent-fetching by txid via the orphan-handling logic).
                if (state.GetResult() == TxValidationResult::TX_INPUTS_NOT_STANDARD && porphanTx->GetWitnessHash() != porphanTx->GetHash()) {
                    // We only add the txid if it differs from the wtxid, to
                    // avoid wasting entries in the rolling bloom filter.
                    m_recent_rejects.insert(porphanTx->GetHash());
                }
            }
            m_orphanage.EraseTx(orphanHash);
            break;
        }
    }
    m_mempool.check(m_chainman.ActiveChainstate());
}

bool PeerManagerImpl::PrepareBlockFilterRequest(CNode& peer,
                                                BlockFilterType filter_type, uint32_t start_height,
                                                const uint256& stop_hash, uint32_t max_height_diff,
                                                const CBlockIndex*& stop_index,
                                                BlockFilterIndex*& filter_index)
{
    const bool supported_filter_type =
        (filter_type == BlockFilterType::BASIC &&
         (peer.GetLocalServices() & NODE_COMPACT_FILTERS));
    if (!supported_filter_type) {
        LogPrint(BCLog::NET, "peer %d requested unsupported block filter type: %d\n",
                 peer.GetId(), static_cast<uint8_t>(filter_type));
        peer.fDisconnect = true;
        return false;
    }

    {
        LOCK(cs_main);
        stop_index = m_chainman.m_blockman.LookupBlockIndex(stop_hash);

        // Check that the stop block exists and the peer would be allowed to fetch it.
        if (!stop_index || !BlockRequestAllowed(stop_index)) {
            LogPrint(BCLog::NET, "peer %d requested invalid block hash: %s\n",
                     peer.GetId(), stop_hash.ToString());
            peer.fDisconnect = true;
            return false;
        }
    }

    uint32_t stop_height = stop_index->nHeight;
    if (start_height > stop_height) {
        LogPrint(BCLog::NET, "peer %d sent invalid getcfilters/getcfheaders with " /* Continued */
                 "start height %d and stop height %d\n",
                 peer.GetId(), start_height, stop_height);
        peer.fDisconnect = true;
        return false;
    }
    if (stop_height - start_height >= max_height_diff) {
        LogPrint(BCLog::NET, "peer %d requested too many cfilters/cfheaders: %d / %d\n",
                 peer.GetId(), stop_height - start_height + 1, max_height_diff);
        peer.fDisconnect = true;
        return false;
    }

    filter_index = GetBlockFilterIndex(filter_type);
    if (!filter_index) {
        LogPrint(BCLog::NET, "Filter index for supported type %s not found\n", BlockFilterTypeName(filter_type));
        return false;
    }

    return true;
}

void PeerManagerImpl::ProcessGetCFilters(CNode& peer, CDataStream& vRecv)
{
    uint8_t filter_type_ser;
    uint32_t start_height;
    uint256 stop_hash;

    vRecv >> filter_type_ser >> start_height >> stop_hash;

    const BlockFilterType filter_type = static_cast<BlockFilterType>(filter_type_ser);

    const CBlockIndex* stop_index;
    BlockFilterIndex* filter_index;
    if (!PrepareBlockFilterRequest(peer, filter_type, start_height, stop_hash,
                                   MAX_GETCFILTERS_SIZE, stop_index, filter_index)) {
        return;
    }

    std::vector<BlockFilter> filters;
    if (!filter_index->LookupFilterRange(start_height, stop_index, filters)) {
        LogPrint(BCLog::NET, "Failed to find block filter in index: filter_type=%s, start_height=%d, stop_hash=%s\n",
                     BlockFilterTypeName(filter_type), start_height, stop_hash.ToString());
        return;
    }

    for (const auto& filter : filters) {
        CSerializedNetMsg msg = CNetMsgMaker(peer.GetCommonVersion())
            .Make(NetMsgType::CFILTER, filter);
        m_connman.PushMessage(&peer, std::move(msg));
    }
}

void PeerManagerImpl::ProcessGetCFHeaders(CNode& peer, CDataStream& vRecv)
{
    uint8_t filter_type_ser;
    uint32_t start_height;
    uint256 stop_hash;

    vRecv >> filter_type_ser >> start_height >> stop_hash;

    const BlockFilterType filter_type = static_cast<BlockFilterType>(filter_type_ser);

    const CBlockIndex* stop_index;
    BlockFilterIndex* filter_index;
    if (!PrepareBlockFilterRequest(peer, filter_type, start_height, stop_hash,
                                   MAX_GETCFHEADERS_SIZE, stop_index, filter_index)) {
        return;
    }

    uint256 prev_header;
    if (start_height > 0) {
        const CBlockIndex* const prev_block =
            stop_index->GetAncestor(static_cast<int>(start_height - 1));
        if (!filter_index->LookupFilterHeader(prev_block, prev_header)) {
            LogPrint(BCLog::NET, "Failed to find block filter header in index: filter_type=%s, block_hash=%s\n",
                         BlockFilterTypeName(filter_type), prev_block->GetBlockHash().ToString());
            return;
        }
    }

    std::vector<uint256> filter_hashes;
    if (!filter_index->LookupFilterHashRange(start_height, stop_index, filter_hashes)) {
        LogPrint(BCLog::NET, "Failed to find block filter hashes in index: filter_type=%s, start_height=%d, stop_hash=%s\n",
                     BlockFilterTypeName(filter_type), start_height, stop_hash.ToString());
        return;
    }

    CSerializedNetMsg msg = CNetMsgMaker(peer.GetCommonVersion())
        .Make(NetMsgType::CFHEADERS,
              filter_type_ser,
              stop_index->GetBlockHash(),
              prev_header,
              filter_hashes);
    m_connman.PushMessage(&peer, std::move(msg));
}

void PeerManagerImpl::ProcessGetCFCheckPt(CNode& peer, CDataStream& vRecv)
{
    uint8_t filter_type_ser;
    uint256 stop_hash;

    vRecv >> filter_type_ser >> stop_hash;

    const BlockFilterType filter_type = static_cast<BlockFilterType>(filter_type_ser);

    const CBlockIndex* stop_index;
    BlockFilterIndex* filter_index;
    if (!PrepareBlockFilterRequest(peer, filter_type, /*start_height=*/0, stop_hash,
                                   /*max_height_diff=*/std::numeric_limits<uint32_t>::max(),
                                   stop_index, filter_index)) {
        return;
    }

    std::vector<uint256> headers(stop_index->nHeight / CFCHECKPT_INTERVAL);

    // Populate headers.
    const CBlockIndex* block_index = stop_index;
    for (int i = headers.size() - 1; i >= 0; i--) {
        int height = (i + 1) * CFCHECKPT_INTERVAL;
        block_index = block_index->GetAncestor(height);

        if (!filter_index->LookupFilterHeader(block_index, headers[i])) {
            LogPrint(BCLog::NET, "Failed to find block filter header in index: filter_type=%s, block_hash=%s\n",
                         BlockFilterTypeName(filter_type), block_index->GetBlockHash().ToString());
            return;
        }
    }

    CSerializedNetMsg msg = CNetMsgMaker(peer.GetCommonVersion())
        .Make(NetMsgType::CFCHECKPT,
              filter_type_ser,
              stop_index->GetBlockHash(),
              headers);
    m_connman.PushMessage(&peer, std::move(msg));
}

void PeerManagerImpl::ProcessBlock(CNode& node, const std::shared_ptr<const CBlock>& block, bool force_processing)
{
    bool new_block{false};
    m_chainman.ProcessNewBlock(m_chainparams, block, force_processing, &new_block);
    if (new_block) {
        node.nLastBlockTime = GetTime();
    } else {
        LOCK(cs_main);
        mapBlockSource.erase(block->GetHash());
    }
}

void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type, CDataStream& vRecv,
                                     const std::chrono::microseconds time_received,
                                     const std::atomic<bool>& interruptMsgProc)
{
    LogPrint(BCLog::NET, "received: %s (%u bytes) peer=%d\n", SanitizeString(msg_type), vRecv.size(), pfrom.GetId());

    PeerRef peer = GetPeerRef(pfrom.GetId());
    if (peer == nullptr) return;

    if (msg_type == NetMsgType::VERSION) {
        if (pfrom.nVersion != 0) {
            LogPrint(BCLog::NET, "redundant version message from peer=%d\n", pfrom.GetId());
            return;
        }

        int64_t nTime;
        CService addrMe;
        uint64_t nNonce = 1;
        ServiceFlags nServices;
        int nVersion;
        std::string cleanSubVer;
        int starting_height = -1;
        bool fRelay = true;

        vRecv >> nVersion >> Using<CustomUintFormatter<8>>(nServices) >> nTime;
        if (nTime < 0) {
            nTime = 0;
        }
        vRecv.ignore(8); // Ignore the addrMe service bits sent by the peer
        vRecv >> addrMe;
        if (!pfrom.IsInboundConn())
        {
            m_addrman.SetServices(pfrom.addr, nServices);
        }
        if (pfrom.ExpectServicesFromConn() && !HasAllDesirableServiceFlags(nServices))
        {
            LogPrint(BCLog::NET, "peer=%d does not offer the expected services (%08x offered, %08x expected); disconnecting\n", pfrom.GetId(), nServices, GetDesirableServiceFlags(nServices));
            pfrom.fDisconnect = true;
            return;
        }

        if (nVersion < MIN_PEER_PROTO_VERSION) {
            // disconnect from peers older than this proto version
            LogPrint(BCLog::NET, "peer=%d using obsolete version %i; disconnecting\n", pfrom.GetId(), nVersion);
            pfrom.fDisconnect = true;
            return;
        }

        if (!vRecv.empty()) {
            // The version message includes information about the sending node which we don't use:
            //   - 8 bytes (service bits)
            //   - 16 bytes (ipv6 address)
            //   - 2 bytes (port)
            vRecv.ignore(26);
            vRecv >> nNonce;
        }
        if (!vRecv.empty()) {
            std::string strSubVer;
            vRecv >> LIMITED_STRING(strSubVer, MAX_SUBVERSION_LENGTH);
            cleanSubVer = SanitizeString(strSubVer);
        }
        if (!vRecv.empty()) {
            vRecv >> starting_height;
        }
        if (!vRecv.empty())
            vRecv >> fRelay;
        // Disconnect if we connected to ourself
        if (pfrom.IsInboundConn() && !m_connman.CheckIncomingNonce(nNonce))
        {
            LogPrintf("connected to self at %s, disconnecting\n", pfrom.addr.ToString());
            pfrom.fDisconnect = true;
            return;
        }

        if (pfrom.IsInboundConn() && addrMe.IsRoutable())
        {
            SeenLocal(addrMe);
        }

        // Inbound peers send us their version message when they connect.
        // We send our version message in response.
        if (pfrom.IsInboundConn()) PushNodeVersion(pfrom, GetAdjustedTime());

        // Change version
        const int greatest_common_version = std::min(nVersion, PROTOCOL_VERSION);
        pfrom.SetCommonVersion(greatest_common_version);
        pfrom.nVersion = nVersion;

        const CNetMsgMaker msg_maker(greatest_common_version);

        if (greatest_common_version >= WTXID_RELAY_VERSION) {
            m_connman.PushMessage(&pfrom, msg_maker.Make(NetMsgType::WTXIDRELAY));
        }

        // Signal ADDRv2 support (BIP155).
        if (greatest_common_version >= 70016) {
            // BIP155 defines addrv2 and sendaddrv2 for all protocol versions, but some
            // implementations reject messages they don't know. As a courtesy, don't send
            // it to nodes with a version before 70016, as no software is known to support
            // BIP155 that doesn't announce at least that protocol version number.
            m_connman.PushMessage(&pfrom, msg_maker.Make(NetMsgType::SENDADDRV2));
        }

        m_connman.PushMessage(&pfrom, msg_maker.Make(NetMsgType::VERACK));

        pfrom.nServices = nServices;
        pfrom.SetAddrLocal(addrMe);
        {
            LOCK(pfrom.cs_SubVer);
            pfrom.cleanSubVer = cleanSubVer;
        }
        peer->m_starting_height = starting_height;

        // set nodes not relaying blocks and tx and not serving (parts) of the historical blockchain as "clients"
        pfrom.fClient = (!(nServices & NODE_NETWORK) && !(nServices & NODE_NETWORK_LIMITED));

        // set nodes not capable of serving the complete blockchain history as "limited nodes"
        pfrom.m_limited_node = (!(nServices & NODE_NETWORK) && (nServices & NODE_NETWORK_LIMITED));

        if (pfrom.m_tx_relay != nullptr) {
            LOCK(pfrom.m_tx_relay->cs_filter);
            pfrom.m_tx_relay->fRelayTxes = fRelay; // set to true after we get the first filter* message
        }

        if((nServices & NODE_WITNESS))
        {
            LOCK(cs_main);
            State(pfrom.GetId())->fHaveWitness = true;
        }

        // Potentially mark this peer as a preferred download peer.
        {
        LOCK(cs_main);
        UpdatePreferredDownload(pfrom, State(pfrom.GetId()));
        }

        // Self advertisement & GETADDR logic
        if (!pfrom.IsInboundConn() && SetupAddressRelay(pfrom, *peer)) {
            // For outbound peers, we try to relay our address (so that other
            // nodes can try to find us more quickly, as we have no guarantee
            // that an outbound peer is even aware of how to reach us) and do a
            // one-time address fetch (to help populate/update our addrman). If
            // we're starting up for the first time, our addrman may be pretty
            // empty and no one will know who we are, so these mechanisms are
            // important to help us connect to the network.
            //
            // We skip this for block-relay-only peers. We want to avoid
            // potentially leaking addr information and we do not want to
            // indicate to the peer that we will participate in addr relay.
            if (fListen && !m_chainman.ActiveChainstate().IsInitialBlockDownload())
            {
                CAddress addr = GetLocalAddress(&pfrom.addr, pfrom.GetLocalServices());
                FastRandomContext insecure_rand;
                if (addr.IsRoutable())
                {
                    LogPrint(BCLog::NET, "ProcessMessages: advertising address %s\n", addr.ToString());
                    PushAddress(*peer, addr, insecure_rand);
                } else if (IsPeerAddrLocalGood(&pfrom)) {
                    addr.SetIP(addrMe);
                    LogPrint(BCLog::NET, "ProcessMessages: advertising address %s\n", addr.ToString());
                    PushAddress(*peer, addr, insecure_rand);
                }
            }

            // Get recent addresses
            m_connman.PushMessage(&pfrom, CNetMsgMaker(greatest_common_version).Make(NetMsgType::GETADDR));
            peer->m_getaddr_sent = true;
            // When requesting a getaddr, accept an additional MAX_ADDR_TO_SEND addresses in response
            // (bypassing the MAX_ADDR_PROCESSING_TOKEN_BUCKET limit).
            peer->m_addr_token_bucket += MAX_ADDR_TO_SEND;
        }

        if (!pfrom.IsInboundConn()) {
            // For non-inbound connections, we update the addrman to record
            // connection success so that addrman will have an up-to-date
            // notion of which peers are online and available.
            //
            // While we strive to not leak information about block-relay-only
            // connections via the addrman, not moving an address to the tried
            // table is also potentially detrimental because new-table entries
            // are subject to eviction in the event of addrman collisions.  We
            // mitigate the information-leak by never calling
            // CAddrMan::Connected() on block-relay-only peers; see
            // FinalizeNode().
            //
            // This moves an address from New to Tried table in Addrman,
            // resolves tried-table collisions, etc.
            m_addrman.Good(pfrom.addr);
        }

        std::string remoteAddr;
        if (fLogIPs)
            remoteAddr = ", peeraddr=" + pfrom.addr.ToString();

        LogPrint(BCLog::NET, "receive version message: %s: version %d, blocks=%d, us=%s, txrelay=%d, peer=%d%s\n",
                  cleanSubVer, pfrom.nVersion,
                  peer->m_starting_height, addrMe.ToString(), fRelay, pfrom.GetId(),
                  remoteAddr);

        int64_t nTimeOffset = nTime - GetTime();
        pfrom.nTimeOffset = nTimeOffset;
        AddTimeData(pfrom.addr, nTimeOffset);

        // If the peer is old enough to have the old alert system, send it the final alert.
        if (greatest_common_version <= 70012) {
            CDataStream finalAlert(ParseHex("60010000000000000000000000ffffff7f00000000ffffff7ffeffff7f01ffffff7f00000000ffffff7f00ffffff7f002f555247454e543a20416c657274206b657920636f6d70726f6d697365642c2075706772616465207265717569726564004630440220653febd6410f470f6bae11cad19c48413becb1ac2c17f908fd0fd53bdc3abd5202206d0e9c96fe88d4a0f01ed9dedae2b6f9e00da94cad0fecaae66ecf689bf71b50"), SER_NETWORK, PROTOCOL_VERSION);
            m_connman.PushMessage(&pfrom, CNetMsgMaker(greatest_common_version).Make("alert", finalAlert));
        }

        // Feeler connections exist only to verify if address is online.
        if (pfrom.IsFeelerConn()) {
            LogPrint(BCLog::NET, "feeler connection completed peer=%d; disconnecting\n", pfrom.GetId());
            pfrom.fDisconnect = true;
        }
        return;
    }

    if (pfrom.nVersion == 0) {
        // Must have a version message before anything else
        LogPrint(BCLog::NET, "non-version message before version handshake. Message \"%s\" from peer=%d\n", SanitizeString(msg_type), pfrom.GetId());
        return;
    }

    // At this point, the outgoing message serialization version can't change.
    const CNetMsgMaker msgMaker(pfrom.GetCommonVersion());

    if (msg_type == NetMsgType::VERACK) {
        if (pfrom.fSuccessfullyConnected) {
            LogPrint(BCLog::NET, "ignoring redundant verack message from peer=%d\n", pfrom.GetId());
            return;
        }

        if (!pfrom.IsInboundConn()) {
            LogPrintf("New outbound peer connected: version: %d, blocks=%d, peer=%d%s (%s)\n",
                      pfrom.nVersion.load(), peer->m_starting_height,
                      pfrom.GetId(), (fLogIPs ? strprintf(", peeraddr=%s", pfrom.addr.ToString()) : ""),
                      pfrom.ConnectionTypeAsString());
        }

        if (pfrom.GetCommonVersion() >= SENDHEADERS_VERSION) {
            // Tell our peer we prefer to receive headers rather than inv's
            // We send this to non-NODE NETWORK peers as well, because even
            // non-NODE NETWORK peers can announce blocks (such as pruning
            // nodes)
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::SENDHEADERS));
        }
        if (pfrom.GetCommonVersion() >= SHORT_IDS_BLOCKS_VERSION) {
            // Tell our peer we are willing to provide version 1 or 2 cmpctblocks
            // However, we do not request new block announcements using
            // cmpctblock messages.
            // We send this to non-NODE NETWORK peers as well, because
            // they may wish to request compact blocks from us
            bool fAnnounceUsingCMPCTBLOCK = false;
            uint64_t nCMPCTBLOCKVersion = 2;
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion));
            nCMPCTBLOCKVersion = 1;
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion));
        }
        pfrom.fSuccessfullyConnected = true;
        return;
    }

    if (msg_type == NetMsgType::SENDHEADERS) {
        LOCK(cs_main);
        State(pfrom.GetId())->fPreferHeaders = true;
        return;
    }

    if (msg_type == NetMsgType::SENDCMPCT) {
        bool fAnnounceUsingCMPCTBLOCK = false;
        uint64_t nCMPCTBLOCKVersion = 0;
        vRecv >> fAnnounceUsingCMPCTBLOCK >> nCMPCTBLOCKVersion;
        if (nCMPCTBLOCKVersion == 1 || nCMPCTBLOCKVersion == 2) {
            LOCK(cs_main);
            // fProvidesHeaderAndIDs is used to "lock in" version of compact blocks we send (fWantsCmpctWitness)
            if (!State(pfrom.GetId())->fProvidesHeaderAndIDs) {
                State(pfrom.GetId())->fProvidesHeaderAndIDs = true;
                State(pfrom.GetId())->fWantsCmpctWitness = nCMPCTBLOCKVersion == 2;
            }
            if (State(pfrom.GetId())->fWantsCmpctWitness == (nCMPCTBLOCKVersion == 2)) { // ignore later version announces
                State(pfrom.GetId())->fPreferHeaderAndIDs = fAnnounceUsingCMPCTBLOCK;
                // save whether peer selects us as BIP152 high-bandwidth peer
                // (receiving sendcmpct(1) signals high-bandwidth, sendcmpct(0) low-bandwidth)
                pfrom.m_bip152_highbandwidth_from = fAnnounceUsingCMPCTBLOCK;
            }
            if (!State(pfrom.GetId())->fSupportsDesiredCmpctVersion) {
                State(pfrom.GetId())->fSupportsDesiredCmpctVersion = (nCMPCTBLOCKVersion == 2);
            }
        }
        return;
    }

    // BIP339 defines feature negotiation of wtxidrelay, which must happen between
    // VERSION and VERACK to avoid relay problems from switching after a connection is up.
    if (msg_type == NetMsgType::WTXIDRELAY) {
        if (pfrom.fSuccessfullyConnected) {
            // Disconnect peers that send a wtxidrelay message after VERACK.
            LogPrint(BCLog::NET, "wtxidrelay received after verack from peer=%d; disconnecting\n", pfrom.GetId());
            pfrom.fDisconnect = true;
            return;
        }
        if (pfrom.GetCommonVersion() >= WTXID_RELAY_VERSION) {
            LOCK(cs_main);
            if (!State(pfrom.GetId())->m_wtxid_relay) {
                State(pfrom.GetId())->m_wtxid_relay = true;
                m_wtxid_relay_peers++;
            } else {
                LogPrint(BCLog::NET, "ignoring duplicate wtxidrelay from peer=%d\n", pfrom.GetId());
            }
        } else {
            LogPrint(BCLog::NET, "ignoring wtxidrelay due to old common version=%d from peer=%d\n", pfrom.GetCommonVersion(), pfrom.GetId());
        }
        return;
    }

    // BIP155 defines feature negotiation of addrv2 and sendaddrv2, which must happen
    // between VERSION and VERACK.
    if (msg_type == NetMsgType::SENDADDRV2) {
        if (pfrom.fSuccessfullyConnected) {
            // Disconnect peers that send a SENDADDRV2 message after VERACK.
            LogPrint(BCLog::NET, "sendaddrv2 received after verack from peer=%d; disconnecting\n", pfrom.GetId());
            pfrom.fDisconnect = true;
            return;
        }
        peer->m_wants_addrv2 = true;
        return;
    }

    if (!pfrom.fSuccessfullyConnected) {
        LogPrint(BCLog::NET, "Unsupported message \"%s\" prior to verack from peer=%d\n", SanitizeString(msg_type), pfrom.GetId());
        return;
    }

    if (msg_type == NetMsgType::ADDR || msg_type == NetMsgType::ADDRV2) {
        int stream_version = vRecv.GetVersion();
        if (msg_type == NetMsgType::ADDRV2) {
            // Add ADDRV2_FORMAT to the version so that the CNetAddr and CAddress
            // unserialize methods know that an address in v2 format is coming.
            stream_version |= ADDRV2_FORMAT;
        }

        OverrideStream<CDataStream> s(&vRecv, vRecv.GetType(), stream_version);
        std::vector<CAddress> vAddr;

        s >> vAddr;

        if (!SetupAddressRelay(pfrom, *peer)) {
            LogPrint(BCLog::NET, "ignoring %s message from %s peer=%d\n", msg_type, pfrom.ConnectionTypeAsString(), pfrom.GetId());
            return;
        }

        if (vAddr.size() > MAX_ADDR_TO_SEND)
        {
            Misbehaving(pfrom.GetId(), 20, strprintf("%s message size = %u", msg_type, vAddr.size()));
            return;
        }

        // Store the new addresses
        std::vector<CAddress> vAddrOk;
        int64_t nNow = GetAdjustedTime();
        int64_t nSince = nNow - 10 * 60;

        // Update/increment addr rate limiting bucket.
        const auto current_time = GetTime<std::chrono::microseconds>();
        if (peer->m_addr_token_bucket < MAX_ADDR_PROCESSING_TOKEN_BUCKET) {
            // Don't increment bucket if it's already full
            const auto time_diff = std::max(current_time - peer->m_addr_token_timestamp, 0us);
            const double increment = CountSecondsDouble(time_diff) * MAX_ADDR_RATE_PER_SECOND;
            peer->m_addr_token_bucket = std::min<double>(peer->m_addr_token_bucket + increment, MAX_ADDR_PROCESSING_TOKEN_BUCKET);
        }
        peer->m_addr_token_timestamp = current_time;

        const bool rate_limited = !pfrom.HasPermission(NetPermissionFlags::Addr);
        uint64_t num_proc = 0;
        uint64_t num_rate_limit = 0;
        Shuffle(vAddr.begin(), vAddr.end(), FastRandomContext());
        for (CAddress& addr : vAddr)
        {
            if (interruptMsgProc)
                return;

            // Apply rate limiting.
            if (peer->m_addr_token_bucket < 1.0) {
                if (rate_limited) {
                    ++num_rate_limit;
                    continue;
                }
            } else {
                peer->m_addr_token_bucket -= 1.0;
            }
            // We only bother storing full nodes, though this may include
            // things which we would not make an outbound connection to, in
            // part because we may make feeler connections to them.
            if (!MayHaveUsefulAddressDB(addr.nServices) && !HasAllDesirableServiceFlags(addr.nServices))
                continue;

            if (addr.nTime <= 100000000 || addr.nTime > nNow + 10 * 60)
                addr.nTime = nNow - 5 * 24 * 60 * 60;
            AddAddressKnown(*peer, addr);
            if (m_banman && (m_banman->IsDiscouraged(addr) || m_banman->IsBanned(addr))) {
                // Do not process banned/discouraged addresses beyond remembering we received them
                continue;
            }
            ++num_proc;
            bool fReachable = IsReachable(addr);
            if (addr.nTime > nSince && !peer->m_getaddr_sent && vAddr.size() <= 10 && addr.IsRoutable()) {
                // Relay to a limited number of other nodes
                RelayAddress(pfrom.GetId(), addr, fReachable);
            }
            // Do not store addresses outside our network
            if (fReachable)
                vAddrOk.push_back(addr);
        }
        peer->m_addr_processed += num_proc;
        peer->m_addr_rate_limited += num_rate_limit;
        LogPrint(BCLog::NET, "Received addr: %u addresses (%u processed, %u rate-limited) from peer=%d\n",
                 vAddr.size(), num_proc, num_rate_limit, pfrom.GetId());

        m_addrman.Add(vAddrOk, pfrom.addr, 2 * 60 * 60);
        if (vAddr.size() < 1000) peer->m_getaddr_sent = false;

        // AddrFetch: Require multiple addresses to avoid disconnecting on self-announcements
        if (pfrom.IsAddrFetchConn() && vAddr.size() > 1) {
            LogPrint(BCLog::NET, "addrfetch connection completed peer=%d; disconnecting\n", pfrom.GetId());
            pfrom.fDisconnect = true;
        }
        return;
    }

    if (msg_type == NetMsgType::INV) {
        std::vector<CInv> vInv;
        vRecv >> vInv;
        if (vInv.size() > MAX_INV_SZ)
        {
            Misbehaving(pfrom.GetId(), 20, strprintf("inv message size = %u", vInv.size()));
            return;
        }

        // Reject tx INVs when the -blocksonly setting is enabled, or this is a
        // block-relay-only peer
        bool reject_tx_invs{m_ignore_incoming_txs || (pfrom.m_tx_relay == nullptr)};

        // Allow peers with relay permission to send data other than blocks in blocks only mode
        if (pfrom.HasPermission(NetPermissionFlags::Relay)) {
            reject_tx_invs = false;
        }

        LOCK(cs_main);

        const auto current_time = GetTime<std::chrono::microseconds>();
        uint256* best_block{nullptr};

        for (CInv& inv : vInv) {
            if (interruptMsgProc) return;

            // Ignore INVs that don't match wtxidrelay setting.
            // Note that orphan parent fetching always uses MSG_TX GETDATAs regardless of the wtxidrelay setting.
            // This is fine as no INV messages are involved in that process.
            if (State(pfrom.GetId())->m_wtxid_relay) {
                if (inv.IsMsgTx()) continue;
            } else {
                if (inv.IsMsgWtx()) continue;
            }

            if (inv.IsMsgBlk()) {
                const bool fAlreadyHave = AlreadyHaveBlock(inv.hash);
                LogPrint(BCLog::NET, "got inv: %s  %s peer=%d\n", inv.ToString(), fAlreadyHave ? "have" : "new", pfrom.GetId());

                UpdateBlockAvailability(pfrom.GetId(), inv.hash);
                if (!fAlreadyHave && !fImporting && !fReindex && !IsBlockRequested(inv.hash)) {
                    // Headers-first is the primary method of announcement on
                    // the network. If a node fell back to sending blocks by inv,
                    // it's probably for a re-org. The final block hash
                    // provided should be the highest, so send a getheaders and
                    // then fetch the blocks we need to catch up.
                    best_block = &inv.hash;
                }
            } else if (inv.IsGenTxMsg()) {
                const GenTxid gtxid = ToGenTxid(inv);
                const bool fAlreadyHave = AlreadyHaveTx(gtxid);
                LogPrint(BCLog::NET, "got inv: %s  %s peer=%d\n", inv.ToString(), fAlreadyHave ? "have" : "new", pfrom.GetId());

                pfrom.AddKnownTx(inv.hash);
                if (reject_tx_invs) {
                    LogPrint(BCLog::NET, "transaction (%s) inv sent in violation of protocol, disconnecting peer=%d\n", inv.hash.ToString(), pfrom.GetId());
                    pfrom.fDisconnect = true;
                    return;
                } else if (!fAlreadyHave && !m_chainman.ActiveChainstate().IsInitialBlockDownload()) {
                    AddTxAnnouncement(pfrom, gtxid, current_time);
                }
            } else {
                LogPrint(BCLog::NET, "Unknown inv type \"%s\" received from peer=%d\n", inv.ToString(), pfrom.GetId());
            }
        }

        if (best_block != nullptr) {
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETHEADERS, m_chainman.ActiveChain().GetLocator(pindexBestHeader), *best_block));
            LogPrint(BCLog::NET, "getheaders (%d) %s to peer=%d\n", pindexBestHeader->nHeight, best_block->ToString(), pfrom.GetId());
        }

        return;
    }

    if (msg_type == NetMsgType::GETDATA) {
        std::vector<CInv> vInv;
        vRecv >> vInv;
        if (vInv.size() > MAX_INV_SZ)
        {
            Misbehaving(pfrom.GetId(), 20, strprintf("getdata message size = %u", vInv.size()));
            return;
        }

        LogPrint(BCLog::NET, "received getdata (%u invsz) peer=%d\n", vInv.size(), pfrom.GetId());

        if (vInv.size() > 0) {
            LogPrint(BCLog::NET, "received getdata for: %s peer=%d\n", vInv[0].ToString(), pfrom.GetId());
        }

        {
            LOCK(peer->m_getdata_requests_mutex);
            peer->m_getdata_requests.insert(peer->m_getdata_requests.end(), vInv.begin(), vInv.end());
            ProcessGetData(pfrom, *peer, interruptMsgProc);
        }

        return;
    }

    if (msg_type == NetMsgType::GETBLOCKS) {
        CBlockLocator locator;
        uint256 hashStop;
        vRecv >> locator >> hashStop;

        if (locator.vHave.size() > MAX_LOCATOR_SZ) {
            LogPrint(BCLog::NET, "getblocks locator size %lld > %d, disconnect peer=%d\n", locator.vHave.size(), MAX_LOCATOR_SZ, pfrom.GetId());
            pfrom.fDisconnect = true;
            return;
        }

        // We might have announced the currently-being-connected tip using a
        // compact block, which resulted in the peer sending a getblocks
        // request, which we would otherwise respond to without the new block.
        // To avoid this situation we simply verify that we are on our best
        // known chain now. This is super overkill, but we handle it better
        // for getheaders requests, and there are no known nodes which support
        // compact blocks but still use getblocks to request blocks.
        {
            std::shared_ptr<const CBlock> a_recent_block;
            {
                LOCK(cs_most_recent_block);
                a_recent_block = most_recent_block;
            }
            BlockValidationState state;
            if (!m_chainman.ActiveChainstate().ActivateBestChain(state, a_recent_block)) {
                LogPrint(BCLog::NET, "failed to activate chain (%s)\n", state.ToString());
            }
        }

        LOCK(cs_main);

        // Find the last block the caller has in the main chain
        const CBlockIndex* pindex = m_chainman.m_blockman.FindForkInGlobalIndex(m_chainman.ActiveChain(), locator);

        // Send the rest of the chain
        if (pindex)
            pindex = m_chainman.ActiveChain().Next(pindex);
        int nLimit = 500;
        LogPrint(BCLog::NET, "getblocks %d to %s limit %d from peer=%d\n", (pindex ? pindex->nHeight : -1), hashStop.IsNull() ? "end" : hashStop.ToString(), nLimit, pfrom.GetId());
        for (; pindex; pindex = m_chainman.ActiveChain().Next(pindex))
        {
            if (pindex->GetBlockHash() == hashStop)
            {
                LogPrint(BCLog::NET, "  getblocks stopping at %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
                break;
            }
            // If pruning, don't inv blocks unless we have on disk and are likely to still have
            // for some reasonable time window (1 hour) that block relay might require.
            const int nPrunedBlocksLikelyToHave = MIN_BLOCKS_TO_KEEP - 3600 / m_chainparams.GetConsensus().nPowTargetSpacing;
            if (fPruneMode && (!(pindex->nStatus & BLOCK_HAVE_DATA) || pindex->nHeight <= m_chainman.ActiveChain().Tip()->nHeight - nPrunedBlocksLikelyToHave))
            {
                LogPrint(BCLog::NET, " getblocks stopping, pruned or too old block at %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
                break;
            }
            WITH_LOCK(peer->m_block_inv_mutex, peer->m_blocks_for_inv_relay.push_back(pindex->GetBlockHash()));
            if (--nLimit <= 0) {
                // When this block is requested, we'll send an inv that'll
                // trigger the peer to getblocks the next batch of inventory.
                LogPrint(BCLog::NET, "  getblocks stopping at limit %d %s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
                WITH_LOCK(peer->m_block_inv_mutex, {peer->m_continuation_block = pindex->GetBlockHash();});
                break;
            }
        }
        return;
    }

    if (msg_type == NetMsgType::GETBLOCKTXN) {
        BlockTransactionsRequest req;
        vRecv >> req;

        std::shared_ptr<const CBlock> recent_block;
        {
            LOCK(cs_most_recent_block);
            if (most_recent_block_hash == req.blockhash)
                recent_block = most_recent_block;
            // Unlock cs_most_recent_block to avoid cs_main lock inversion
        }
        if (recent_block) {
            SendBlockTransactions(pfrom, *recent_block, req);
            return;
        }

        {
            LOCK(cs_main);

            const CBlockIndex* pindex = m_chainman.m_blockman.LookupBlockIndex(req.blockhash);
            if (!pindex || !(pindex->nStatus & BLOCK_HAVE_DATA)) {
                LogPrint(BCLog::NET, "Peer %d sent us a getblocktxn for a block we don't have\n", pfrom.GetId());
                return;
            }

            if (pindex->nHeight >= m_chainman.ActiveChain().Height() - MAX_BLOCKTXN_DEPTH) {
                CBlock block;
                bool ret = ReadBlockFromDisk(block, pindex, m_chainparams.GetConsensus());
                assert(ret);

                SendBlockTransactions(pfrom, block, req);
                return;
            }
        }

        // If an older block is requested (should never happen in practice,
        // but can happen in tests) send a block response instead of a
        // blocktxn response. Sending a full block response instead of a
        // small blocktxn response is preferable in the case where a peer
        // might maliciously send lots of getblocktxn requests to trigger
        // expensive disk reads, because it will require the peer to
        // actually receive all the data read from disk over the network.
        LogPrint(BCLog::NET, "Peer %d sent us a getblocktxn for a block > %i deep\n", pfrom.GetId(), MAX_BLOCKTXN_DEPTH);
        CInv inv;
        WITH_LOCK(cs_main, inv.type = State(pfrom.GetId())->fWantsCmpctWitness ? MSG_WITNESS_BLOCK : MSG_BLOCK);
        inv.hash = req.blockhash;
        WITH_LOCK(peer->m_getdata_requests_mutex, peer->m_getdata_requests.push_back(inv));
        // The message processing loop will go around again (without pausing) and we'll respond then
        return;
    }

    if (msg_type == NetMsgType::GETHEADERS) {
        CBlockLocator locator;
        uint256 hashStop;
        vRecv >> locator >> hashStop;

        if (locator.vHave.size() > MAX_LOCATOR_SZ) {
            LogPrint(BCLog::NET, "getheaders locator size %lld > %d, disconnect peer=%d\n", locator.vHave.size(), MAX_LOCATOR_SZ, pfrom.GetId());
            pfrom.fDisconnect = true;
            return;
        }

        LOCK(cs_main);
        if (m_chainman.ActiveChainstate().IsInitialBlockDownload() && !pfrom.HasPermission(NetPermissionFlags::Download)) {
            LogPrint(BCLog::NET, "Ignoring getheaders from peer=%d because node is in initial block download\n", pfrom.GetId());
            return;
        }

        CNodeState *nodestate = State(pfrom.GetId());
        const CBlockIndex* pindex = nullptr;
        if (locator.IsNull())
        {
            // If locator is null, return the hashStop block
            pindex = m_chainman.m_blockman.LookupBlockIndex(hashStop);
            if (!pindex) {
                return;
            }

            if (!BlockRequestAllowed(pindex)) {
                LogPrint(BCLog::NET, "%s: ignoring request from peer=%i for old block header that isn't in the main chain\n", __func__, pfrom.GetId());
                return;
            }
        }
        else
        {
            // Find the last block the caller has in the main chain
            pindex = m_chainman.m_blockman.FindForkInGlobalIndex(m_chainman.ActiveChain(), locator);
            if (pindex)
                pindex = m_chainman.ActiveChain().Next(pindex);
        }

        // we must use CBlocks, as CBlockHeaders won't include the 0x00 nTx count at the end
        std::vector<CBlock> vHeaders;
        int nLimit = MAX_HEADERS_RESULTS;
        LogPrint(BCLog::NET, "getheaders %d to %s from peer=%d\n", (pindex ? pindex->nHeight : -1), hashStop.IsNull() ? "end" : hashStop.ToString(), pfrom.GetId());
        for (; pindex; pindex = m_chainman.ActiveChain().Next(pindex))
        {
            vHeaders.push_back(pindex->GetBlockHeader());
            if (--nLimit <= 0 || pindex->GetBlockHash() == hashStop)
                break;
        }
        // pindex can be nullptr either if we sent m_chainman.ActiveChain().Tip() OR
        // if our peer has m_chainman.ActiveChain().Tip() (and thus we are sending an empty
        // headers message). In both cases it's safe to update
        // pindexBestHeaderSent to be our tip.
        //
        // It is important that we simply reset the BestHeaderSent value here,
        // and not max(BestHeaderSent, newHeaderSent). We might have announced
        // the currently-being-connected tip using a compact block, which
        // resulted in the peer sending a headers request, which we respond to
        // without the new block. By resetting the BestHeaderSent, we ensure we
        // will re-announce the new block via headers (or compact blocks again)
        // in the SendMessages logic.
        nodestate->pindexBestHeaderSent = pindex ? pindex : m_chainman.ActiveChain().Tip();
        m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::HEADERS, vHeaders));
        return;
    }

    if (msg_type == NetMsgType::TX) {
        // Stop processing the transaction early if
        // 1) We are in blocks only mode and peer has no relay permission
        // 2) This peer is a block-relay-only peer
        if ((m_ignore_incoming_txs && !pfrom.HasPermission(NetPermissionFlags::Relay)) || (pfrom.m_tx_relay == nullptr))
        {
            LogPrint(BCLog::NET, "transaction sent in violation of protocol peer=%d\n", pfrom.GetId());
            pfrom.fDisconnect = true;
            return;
        }

        CTransactionRef ptx;
        vRecv >> ptx;
        const CTransaction& tx = *ptx;

        const uint256& txid = ptx->GetHash();
        const uint256& wtxid = ptx->GetWitnessHash();

        LOCK2(cs_main, g_cs_orphans);

        CNodeState* nodestate = State(pfrom.GetId());

        const uint256& hash = nodestate->m_wtxid_relay ? wtxid : txid;
        pfrom.AddKnownTx(hash);
        if (nodestate->m_wtxid_relay && txid != wtxid) {
            // Insert txid into filterInventoryKnown, even for
            // wtxidrelay peers. This prevents re-adding of
            // unconfirmed parents to the recently_announced
            // filter, when a child tx is requested. See
            // ProcessGetData().
            pfrom.AddKnownTx(txid);
        }

        m_txrequest.ReceivedResponse(pfrom.GetId(), txid);
        if (tx.HasWitness()) m_txrequest.ReceivedResponse(pfrom.GetId(), wtxid);

        // We do the AlreadyHaveTx() check using wtxid, rather than txid - in the
        // absence of witness malleation, this is strictly better, because the
        // recent rejects filter may contain the wtxid but rarely contains
        // the txid of a segwit transaction that has been rejected.
        // In the presence of witness malleation, it's possible that by only
        // doing the check with wtxid, we could overlook a transaction which
        // was confirmed with a different witness, or exists in our mempool
        // with a different witness, but this has limited downside:
        // mempool validation does its own lookup of whether we have the txid
        // already; and an adversary can already relay us old transactions
        // (older than our recency filter) if trying to DoS us, without any need
        // for witness malleation.
        if (AlreadyHaveTx(GenTxid(/* is_wtxid=*/true, wtxid))) {
            if (pfrom.HasPermission(NetPermissionFlags::ForceRelay)) {
                // Always relay transactions received from peers with forcerelay
                // permission, even if they were already in the mempool, allowing
                // the node to function as a gateway for nodes hidden behind it.
                if (!m_mempool.exists(tx.GetHash())) {
                    LogPrintf("Not relaying non-mempool transaction %s from forcerelay peer=%d\n", tx.GetHash().ToString(), pfrom.GetId());
                } else {
                    LogPrintf("Force relaying tx %s from peer=%d\n", tx.GetHash().ToString(), pfrom.GetId());
                    _RelayTransaction(tx.GetHash(), tx.GetWitnessHash());
                }
            }
            return;
        }

        const MempoolAcceptResult result = AcceptToMemoryPool(m_chainman.ActiveChainstate(), m_mempool, ptx, false /* bypass_limits */);
        const TxValidationState& state = result.m_state;

        if (result.m_result_type == MempoolAcceptResult::ResultType::VALID) {
            m_mempool.check(m_chainman.ActiveChainstate());
            // As this version of the transaction was acceptable, we can forget about any
            // requests for it.
            m_txrequest.ForgetTxHash(tx.GetHash());
            m_txrequest.ForgetTxHash(tx.GetWitnessHash());
            _RelayTransaction(tx.GetHash(), tx.GetWitnessHash());
            m_orphanage.AddChildrenToWorkSet(tx, peer->m_orphan_work_set);

            pfrom.nLastTXTime = GetTime();

            LogPrint(BCLog::MEMPOOL, "AcceptToMemoryPool: peer=%d: accepted %s (poolsz %u txn, %u kB)\n",
                pfrom.GetId(),
                tx.GetHash().ToString(),
                m_mempool.size(), m_mempool.DynamicMemoryUsage() / 1000);

            for (const CTransactionRef& removedTx : result.m_replaced_transactions.value()) {
                AddToCompactExtraTransactions(removedTx);
            }

            // Recursively process any orphan transactions that depended on this one
            ProcessOrphanTx(peer->m_orphan_work_set);
        }
        else if (state.GetResult() == TxValidationResult::TX_MISSING_INPUTS)
        {
            bool fRejectedParents = false; // It may be the case that the orphans parents have all been rejected

            // Deduplicate parent txids, so that we don't have to loop over
            // the same parent txid more than once down below.
            std::vector<uint256> unique_parents;
            unique_parents.reserve(tx.vin.size());
            for (const CTxIn& txin : tx.vin) {
                // We start with all parents, and then remove duplicates below.
                unique_parents.push_back(txin.prevout.hash);
            }
            std::sort(unique_parents.begin(), unique_parents.end());
            unique_parents.erase(std::unique(unique_parents.begin(), unique_parents.end()), unique_parents.end());
            for (const uint256& parent_txid : unique_parents) {
                if (m_recent_rejects.contains(parent_txid)) {
                    fRejectedParents = true;
                    break;
                }
            }
            if (!fRejectedParents) {
                const auto current_time = GetTime<std::chrono::microseconds>();

                for (const uint256& parent_txid : unique_parents) {
                    // Here, we only have the txid (and not wtxid) of the
                    // inputs, so we only request in txid mode, even for
                    // wtxidrelay peers.
                    // Eventually we should replace this with an improved
                    // protocol for getting all unconfirmed parents.
                    const GenTxid gtxid{/* is_wtxid=*/false, parent_txid};
                    pfrom.AddKnownTx(parent_txid);
                    if (!AlreadyHaveTx(gtxid)) AddTxAnnouncement(pfrom, gtxid, current_time);
                }

                if (m_orphanage.AddTx(ptx, pfrom.GetId())) {
                    AddToCompactExtraTransactions(ptx);
                }

                // Once added to the orphan pool, a tx is considered AlreadyHave, and we shouldn't request it anymore.
                m_txrequest.ForgetTxHash(tx.GetHash());
                m_txrequest.ForgetTxHash(tx.GetWitnessHash());

                // DoS prevention: do not allow m_orphanage to grow unbounded (see CVE-2012-3789)
                unsigned int nMaxOrphanTx = (unsigned int)std::max((int64_t)0, gArgs.GetArg("-maxorphantx", DEFAULT_MAX_ORPHAN_TRANSACTIONS));
                unsigned int nEvicted = m_orphanage.LimitOrphans(nMaxOrphanTx);
                if (nEvicted > 0) {
                    LogPrint(BCLog::MEMPOOL, "orphanage overflow, removed %u tx\n", nEvicted);
                }
            } else {
                LogPrint(BCLog::MEMPOOL, "not keeping orphan with rejected parents %s\n",tx.GetHash().ToString());
                // We will continue to reject this tx since it has rejected
                // parents so avoid re-requesting it from other peers.
                // Here we add both the txid and the wtxid, as we know that
                // regardless of what witness is provided, we will not accept
                // this, so we don't need to allow for redownload of this txid
                // from any of our non-wtxidrelay peers.
                m_recent_rejects.insert(tx.GetHash());
                m_recent_rejects.insert(tx.GetWitnessHash());
                m_txrequest.ForgetTxHash(tx.GetHash());
                m_txrequest.ForgetTxHash(tx.GetWitnessHash());
            }
        } else {
            if (state.GetResult() != TxValidationResult::TX_WITNESS_STRIPPED) {
                // We can add the wtxid of this transaction to our reject filter.
                // Do not add txids of witness transactions or witness-stripped
                // transactions to the filter, as they can have been malleated;
                // adding such txids to the reject filter would potentially
                // interfere with relay of valid transactions from peers that
                // do not support wtxid-based relay. See
                // https://github.com/bitcoin/bitcoin/issues/8279 for details.
                // We can remove this restriction (and always add wtxids to
                // the filter even for witness stripped transactions) once
                // wtxid-based relay is broadly deployed.
                // See also comments in https://github.com/bitcoin/bitcoin/pull/18044#discussion_r443419034
                // for concerns around weakening security of unupgraded nodes
                // if we start doing this too early.
                m_recent_rejects.insert(tx.GetWitnessHash());
                m_txrequest.ForgetTxHash(tx.GetWitnessHash());
                // If the transaction failed for TX_INPUTS_NOT_STANDARD,
                // then we know that the witness was irrelevant to the policy
                // failure, since this check depends only on the txid
                // (the scriptPubKey being spent is covered by the txid).
                // Add the txid to the reject filter to prevent repeated
                // processing of this transaction in the event that child
                // transactions are later received (resulting in
                // parent-fetching by txid via the orphan-handling logic).
                if (state.GetResult() == TxValidationResult::TX_INPUTS_NOT_STANDARD && tx.GetWitnessHash() != tx.GetHash()) {
                    m_recent_rejects.insert(tx.GetHash());
                    m_txrequest.ForgetTxHash(tx.GetHash());
                }
                if (RecursiveDynamicUsage(*ptx) < 100000) {
                    AddToCompactExtraTransactions(ptx);
                }
            }
        }

        // If a tx has been detected by m_recent_rejects, we will have reached
        // this point and the tx will have been ignored. Because we haven't run
        // the tx through AcceptToMemoryPool, we won't have computed a DoS
        // score for it or determined exactly why we consider it invalid.
        //
        // This means we won't penalize any peer subsequently relaying a DoSy
        // tx (even if we penalized the first peer who gave it to us) because
        // we have to account for m_recent_rejects showing false positives. In
        // other words, we shouldn't penalize a peer if we aren't *sure* they
        // submitted a DoSy tx.
        //
        // Note that m_recent_rejects doesn't just record DoSy or invalid
        // transactions, but any tx not accepted by the mempool, which may be
        // due to node policy (vs. consensus). So we can't blanket penalize a
        // peer simply for relaying a tx that our m_recent_rejects has caught,
        // regardless of false positives.

        if (state.IsInvalid()) {
            LogPrint(BCLog::MEMPOOLREJ, "%s from peer=%d was not accepted: %s\n", tx.GetHash().ToString(),
                pfrom.GetId(),
                state.ToString());
            MaybePunishNodeForTx(pfrom.GetId(), state);
        }
        return;
    }

    if (msg_type == NetMsgType::CMPCTBLOCK)
    {
        // Ignore cmpctblock received while importing
        if (fImporting || fReindex) {
            LogPrint(BCLog::NET, "Unexpected cmpctblock message received from peer %d\n", pfrom.GetId());
            return;
        }

        CBlockHeaderAndShortTxIDs cmpctblock;
        vRecv >> cmpctblock;

        bool received_new_header = false;

        {
        LOCK(cs_main);

        if (!m_chainman.m_blockman.LookupBlockIndex(cmpctblock.header.hashPrevBlock)) {
            // Doesn't connect (or is genesis), instead of DoSing in AcceptBlockHeader, request deeper headers
            if (!m_chainman.ActiveChainstate().IsInitialBlockDownload())
                m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETHEADERS, m_chainman.ActiveChain().GetLocator(pindexBestHeader), uint256()));
            return;
        }

        if (!m_chainman.m_blockman.LookupBlockIndex(cmpctblock.header.GetHash())) {
            received_new_header = true;
        }
        }

        const CBlockIndex *pindex = nullptr;
        BlockValidationState state;
        if (!m_chainman.ProcessNewBlockHeaders({cmpctblock.header}, state, m_chainparams, &pindex)) {
            if (state.IsInvalid()) {
                MaybePunishNodeForBlock(pfrom.GetId(), state, /*via_compact_block*/ true, "invalid header via cmpctblock");
                return;
            }
        }

        // When we succeed in decoding a block's txids from a cmpctblock
        // message we typically jump to the BLOCKTXN handling code, with a
        // dummy (empty) BLOCKTXN message, to re-use the logic there in
        // completing processing of the putative block (without cs_main).
        bool fProcessBLOCKTXN = false;
        CDataStream blockTxnMsg(SER_NETWORK, PROTOCOL_VERSION);

        // If we end up treating this as a plain headers message, call that as well
        // without cs_main.
        bool fRevertToHeaderProcessing = false;

        // Keep a CBlock for "optimistic" compactblock reconstructions (see
        // below)
        std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
        bool fBlockReconstructed = false;

        {
        LOCK2(cs_main, g_cs_orphans);
        // If AcceptBlockHeader returned true, it set pindex
        assert(pindex);
        UpdateBlockAvailability(pfrom.GetId(), pindex->GetBlockHash());

        CNodeState *nodestate = State(pfrom.GetId());

        // If this was a new header with more work than our tip, update the
        // peer's last block announcement time
        if (received_new_header && pindex->nChainWork > m_chainman.ActiveChain().Tip()->nChainWork) {
            nodestate->m_last_block_announcement = GetTime();
        }

        std::map<uint256, std::pair<NodeId, std::list<QueuedBlock>::iterator> >::iterator blockInFlightIt = mapBlocksInFlight.find(pindex->GetBlockHash());
        bool fAlreadyInFlight = blockInFlightIt != mapBlocksInFlight.end();

        if (pindex->nStatus & BLOCK_HAVE_DATA) // Nothing to do here
            return;

        if (pindex->nChainWork <= m_chainman.ActiveChain().Tip()->nChainWork || // We know something better
                pindex->nTx != 0) { // We had this block at some point, but pruned it
            if (fAlreadyInFlight) {
                // We requested this block for some reason, but our mempool will probably be useless
                // so we just grab the block via normal getdata
                std::vector<CInv> vInv(1);
                vInv[0] = CInv(MSG_BLOCK | GetFetchFlags(pfrom), cmpctblock.header.GetHash());
                m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETDATA, vInv));
            }
            return;
        }

        // If we're not close to tip yet, give up and let parallel block fetch work its magic
        if (!fAlreadyInFlight && !CanDirectFetch()) {
            return;
        }

        if (DeploymentActiveAt(*pindex, m_chainparams.GetConsensus(), Consensus::DEPLOYMENT_SEGWIT) && !nodestate->fSupportsDesiredCmpctVersion) {
            // Don't bother trying to process compact blocks from v1 peers
            // after segwit activates.
            return;
        }

        // We want to be a bit conservative just to be extra careful about DoS
        // possibilities in compact block processing...
        if (pindex->nHeight <= m_chainman.ActiveChain().Height() + 2) {
            if ((!fAlreadyInFlight && nodestate->nBlocksInFlight < MAX_BLOCKS_IN_TRANSIT_PER_PEER) ||
                 (fAlreadyInFlight && blockInFlightIt->second.first == pfrom.GetId())) {
                std::list<QueuedBlock>::iterator* queuedBlockIt = nullptr;
                if (!BlockRequested(pfrom.GetId(), *pindex, &queuedBlockIt)) {
                    if (!(*queuedBlockIt)->partialBlock)
                        (*queuedBlockIt)->partialBlock.reset(new PartiallyDownloadedBlock(&m_mempool));
                    else {
                        // The block was already in flight using compact blocks from the same peer
                        LogPrint(BCLog::NET, "Peer sent us compact block we were already syncing!\n");
                        return;
                    }
                }

                PartiallyDownloadedBlock& partialBlock = *(*queuedBlockIt)->partialBlock;
                ReadStatus status = partialBlock.InitData(cmpctblock, vExtraTxnForCompact);
                if (status == READ_STATUS_INVALID) {
                    RemoveBlockRequest(pindex->GetBlockHash()); // Reset in-flight state in case Misbehaving does not result in a disconnect
                    Misbehaving(pfrom.GetId(), 100, "invalid compact block");
                    return;
                } else if (status == READ_STATUS_FAILED) {
                    // Duplicate txindexes, the block is now in-flight, so just request it
                    std::vector<CInv> vInv(1);
                    vInv[0] = CInv(MSG_BLOCK | GetFetchFlags(pfrom), cmpctblock.header.GetHash());
                    m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETDATA, vInv));
                    return;
                }

                BlockTransactionsRequest req;
                for (size_t i = 0; i < cmpctblock.BlockTxCount(); i++) {
                    if (!partialBlock.IsTxAvailable(i))
                        req.indexes.push_back(i);
                }
                if (req.indexes.empty()) {
                    // Dirty hack to jump to BLOCKTXN code (TODO: move message handling into their own functions)
                    BlockTransactions txn;
                    txn.blockhash = cmpctblock.header.GetHash();
                    blockTxnMsg << txn;
                    fProcessBLOCKTXN = true;
                } else {
                    req.blockhash = pindex->GetBlockHash();
                    m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETBLOCKTXN, req));
                }
            } else {
                // This block is either already in flight from a different
                // peer, or this peer has too many blocks outstanding to
                // download from.
                // Optimistically try to reconstruct anyway since we might be
                // able to without any round trips.
                PartiallyDownloadedBlock tempBlock(&m_mempool);
                ReadStatus status = tempBlock.InitData(cmpctblock, vExtraTxnForCompact);
                if (status != READ_STATUS_OK) {
                    // TODO: don't ignore failures
                    return;
                }
                std::vector<CTransactionRef> dummy;
                status = tempBlock.FillBlock(*pblock, dummy);
                if (status == READ_STATUS_OK) {
                    fBlockReconstructed = true;
                }
            }
        } else {
            if (fAlreadyInFlight) {
                // We requested this block, but its far into the future, so our
                // mempool will probably be useless - request the block normally
                std::vector<CInv> vInv(1);
                vInv[0] = CInv(MSG_BLOCK | GetFetchFlags(pfrom), cmpctblock.header.GetHash());
                m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETDATA, vInv));
                return;
            } else {
                // If this was an announce-cmpctblock, we want the same treatment as a header message
                fRevertToHeaderProcessing = true;
            }
        }
        } // cs_main

        if (fProcessBLOCKTXN) {
            return ProcessMessage(pfrom, NetMsgType::BLOCKTXN, blockTxnMsg, time_received, interruptMsgProc);
        }

        if (fRevertToHeaderProcessing) {
            // Headers received from HB compact block peers are permitted to be
            // relayed before full validation (see BIP 152), so we don't want to disconnect
            // the peer if the header turns out to be for an invalid block.
            // Note that if a peer tries to build on an invalid chain, that
            // will be detected and the peer will be disconnected/discouraged.
            return ProcessHeadersMessage(pfrom, *peer, {cmpctblock.header}, /*via_compact_block=*/true);
        }

        if (fBlockReconstructed) {
            // If we got here, we were able to optimistically reconstruct a
            // block that is in flight from some other peer.
            {
                LOCK(cs_main);
                mapBlockSource.emplace(pblock->GetHash(), std::make_pair(pfrom.GetId(), false));
            }
            // Setting force_processing to true means that we bypass some of
            // our anti-DoS protections in AcceptBlock, which filters
            // unrequested blocks that might be trying to waste our resources
            // (eg disk space). Because we only try to reconstruct blocks when
            // we're close to caught up (via the CanDirectFetch() requirement
            // above, combined with the behavior of not requesting blocks until
            // we have a chain with at least nMinimumChainWork), and we ignore
            // compact blocks with less work than our tip, it is safe to treat
            // reconstructed compact blocks as having been requested.
            ProcessBlock(pfrom, pblock, /*force_processing=*/true);
            LOCK(cs_main); // hold cs_main for CBlockIndex::IsValid()
            if (pindex->IsValid(BLOCK_VALID_TRANSACTIONS)) {
                // Clear download state for this block, which is in
                // process from some other peer.  We do this after calling
                // ProcessNewBlock so that a malleated cmpctblock announcement
                // can't be used to interfere with block relay.
                RemoveBlockRequest(pblock->GetHash());
            }
        }
        return;
    }

    if (msg_type == NetMsgType::BLOCKTXN)
    {
        // Ignore blocktxn received while importing
        if (fImporting || fReindex) {
            LogPrint(BCLog::NET, "Unexpected blocktxn message received from peer %d\n", pfrom.GetId());
            return;
        }

        BlockTransactions resp;
        vRecv >> resp;

        std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
        bool fBlockRead = false;
        {
            LOCK(cs_main);

            std::map<uint256, std::pair<NodeId, std::list<QueuedBlock>::iterator> >::iterator it = mapBlocksInFlight.find(resp.blockhash);
            if (it == mapBlocksInFlight.end() || !it->second.second->partialBlock ||
                    it->second.first != pfrom.GetId()) {
                LogPrint(BCLog::NET, "Peer %d sent us block transactions for block we weren't expecting\n", pfrom.GetId());
                return;
            }

            PartiallyDownloadedBlock& partialBlock = *it->second.second->partialBlock;
            ReadStatus status = partialBlock.FillBlock(*pblock, resp.txn);
            if (status == READ_STATUS_INVALID) {
                RemoveBlockRequest(resp.blockhash); // Reset in-flight state in case Misbehaving does not result in a disconnect
                Misbehaving(pfrom.GetId(), 100, "invalid compact block/non-matching block transactions");
                return;
            } else if (status == READ_STATUS_FAILED) {
                // Might have collided, fall back to getdata now :(
                std::vector<CInv> invs;
                invs.push_back(CInv(MSG_BLOCK | GetFetchFlags(pfrom), resp.blockhash));
                m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::GETDATA, invs));
            } else {
                // Block is either okay, or possibly we received
                // READ_STATUS_CHECKBLOCK_FAILED.
                // Note that CheckBlock can only fail for one of a few reasons:
                // 1. bad-proof-of-work (impossible here, because we've already
                //    accepted the header)
                // 2. merkleroot doesn't match the transactions given (already
                //    caught in FillBlock with READ_STATUS_FAILED, so
                //    impossible here)
                // 3. the block is otherwise invalid (eg invalid coinbase,
                //    block is too big, too many legacy sigops, etc).
                // So if CheckBlock failed, #3 is the only possibility.
                // Under BIP 152, we don't discourage the peer unless proof of work is
                // invalid (we don't require all the stateless checks to have
                // been run).  This is handled below, so just treat this as
                // though the block was successfully read, and rely on the
                // handling in ProcessNewBlock to ensure the block index is
                // updated, etc.
                RemoveBlockRequest(resp.blockhash); // it is now an empty pointer
                fBlockRead = true;
                // mapBlockSource is used for potentially punishing peers and
                // updating which peers send us compact blocks, so the race
                // between here and cs_main in ProcessNewBlock is fine.
                // BIP 152 permits peers to relay compact blocks after validating
                // the header only; we should not punish peers if the block turns
                // out to be invalid.
                mapBlockSource.emplace(resp.blockhash, std::make_pair(pfrom.GetId(), false));
            }
        } // Don't hold cs_main when we call into ProcessNewBlock
        if (fBlockRead) {
            // Since we requested this block (it was in mapBlocksInFlight), force it to be processed,
            // even if it would not be a candidate for new tip (missing previous block, chain not long enough, etc)
            // This bypasses some anti-DoS logic in AcceptBlock (eg to prevent
            // disk-space attacks), but this should be safe due to the
            // protections in the compact block handler -- see related comment
            // in compact block optimistic reconstruction handling.
            ProcessBlock(pfrom, pblock, /*force_processing=*/true);
        }
        return;
    }

    if (msg_type == NetMsgType::HEADERS)
    {
        // Ignore headers received while importing
        if (fImporting || fReindex) {
            LogPrint(BCLog::NET, "Unexpected headers message received from peer %d\n", pfrom.GetId());
            return;
        }

        std::vector<CBlockHeader> headers;

        // Bypass the normal CBlock deserialization, as we don't want to risk deserializing 2000 full blocks.
        unsigned int nCount = ReadCompactSize(vRecv);
        if (nCount > MAX_HEADERS_RESULTS) {
            Misbehaving(pfrom.GetId(), 20, strprintf("headers message size = %u", nCount));
            return;
        }
        headers.resize(nCount);
        for (unsigned int n = 0; n < nCount; n++) {
            vRecv >> headers[n];
            ReadCompactSize(vRecv); // ignore tx count; assume it is 0.
        }

        return ProcessHeadersMessage(pfrom, *peer, headers, /*via_compact_block=*/false);
    }

    if (msg_type == NetMsgType::BLOCK)
    {
        // Ignore block received while importing
        if (fImporting || fReindex) {
            LogPrint(BCLog::NET, "Unexpected block message received from peer %d\n", pfrom.GetId());
            return;
        }

        std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
        vRecv >> *pblock;

        LogPrint(BCLog::NET, "received block %s peer=%d\n", pblock->GetHash().ToString(), pfrom.GetId());

        bool forceProcessing = false;
        const uint256 hash(pblock->GetHash());
        {
            LOCK(cs_main);
            // Always process the block if we requested it, since we may
            // need it even when it's not a candidate for a new best tip.
            forceProcessing = IsBlockRequested(hash);
            RemoveBlockRequest(hash);
            // mapBlockSource is only used for punishing peers and setting
            // which peers send us compact blocks, so the race between here and
            // cs_main in ProcessNewBlock is fine.
            mapBlockSource.emplace(hash, std::make_pair(pfrom.GetId(), true));
        }
        ProcessBlock(pfrom, pblock, forceProcessing);
        return;
    }

    if (msg_type == NetMsgType::GETADDR) {
        // This asymmetric behavior for inbound and outbound connections was introduced
        // to prevent a fingerprinting attack: an attacker can send specific fake addresses
        // to users' AddrMan and later request them by sending getaddr messages.
        // Making nodes which are behind NAT and can only make outgoing connections ignore
        // the getaddr message mitigates the attack.
        if (!pfrom.IsInboundConn()) {
            LogPrint(BCLog::NET, "Ignoring \"getaddr\" from %s connection. peer=%d\n", pfrom.ConnectionTypeAsString(), pfrom.GetId());
            return;
        }

        // Since this must be an inbound connection, SetupAddressRelay will
        // never fail.
        Assume(SetupAddressRelay(pfrom, *peer));

        // Only send one GetAddr response per connection to reduce resource waste
        // and discourage addr stamping of INV announcements.
        if (peer->m_getaddr_recvd) {
            LogPrint(BCLog::NET, "Ignoring repeated \"getaddr\". peer=%d\n", pfrom.GetId());
            return;
        }
        peer->m_getaddr_recvd = true;

        peer->m_addrs_to_send.clear();
        std::vector<CAddress> vAddr;
        if (pfrom.HasPermission(NetPermissionFlags::Addr)) {
            vAddr = m_connman.GetAddresses(MAX_ADDR_TO_SEND, MAX_PCT_ADDR_TO_SEND, /* network */ std::nullopt);
        } else {
            vAddr = m_connman.GetAddresses(pfrom, MAX_ADDR_TO_SEND, MAX_PCT_ADDR_TO_SEND);
        }
        FastRandomContext insecure_rand;
        for (const CAddress &addr : vAddr) {
            PushAddress(*peer, addr, insecure_rand);
        }
        return;
    }

    if (msg_type == NetMsgType::MEMPOOL) {
        if (!(pfrom.GetLocalServices() & NODE_BLOOM) && !pfrom.HasPermission(NetPermissionFlags::Mempool))
        {
            if (!pfrom.HasPermission(NetPermissionFlags::NoBan))
            {
                LogPrint(BCLog::NET, "mempool request with bloom filters disabled, disconnect peer=%d\n", pfrom.GetId());
                pfrom.fDisconnect = true;
            }
            return;
        }

        if (m_connman.OutboundTargetReached(false) && !pfrom.HasPermission(NetPermissionFlags::Mempool))
        {
            if (!pfrom.HasPermission(NetPermissionFlags::NoBan))
            {
                LogPrint(BCLog::NET, "mempool request with bandwidth limit reached, disconnect peer=%d\n", pfrom.GetId());
                pfrom.fDisconnect = true;
            }
            return;
        }

        if (pfrom.m_tx_relay != nullptr) {
            LOCK(pfrom.m_tx_relay->cs_tx_inventory);
            pfrom.m_tx_relay->fSendMempool = true;
        }
        return;
    }

    if (msg_type == NetMsgType::PING) {
        if (pfrom.GetCommonVersion() > BIP0031_VERSION) {
            uint64_t nonce = 0;
            vRecv >> nonce;
            // Echo the message back with the nonce. This allows for two useful features:
            //
            // 1) A remote node can quickly check if the connection is operational
            // 2) Remote nodes can measure the latency of the network thread. If this node
            //    is overloaded it won't respond to pings quickly and the remote node can
            //    avoid sending us more work, like chain download requests.
            //
            // The nonce stops the remote getting confused between different pings: without
            // it, if the remote node sends a ping once per second and this node takes 5
            // seconds to respond to each, the 5th ping the remote sends would appear to
            // return very quickly.
            m_connman.PushMessage(&pfrom, msgMaker.Make(NetMsgType::PONG, nonce));
        }
        return;
    }

    if (msg_type == NetMsgType::PONG) {
        const auto ping_end = time_received;
        uint64_t nonce = 0;
        size_t nAvail = vRecv.in_avail();
        bool bPingFinished = false;
        std::string sProblem;

        if (nAvail >= sizeof(nonce)) {
            vRecv >> nonce;

            // Only process pong message if there is an outstanding ping (old ping without nonce should never pong)
            if (peer->m_ping_nonce_sent != 0) {
                if (nonce == peer->m_ping_nonce_sent) {
                    // Matching pong received, this ping is no longer outstanding
                    bPingFinished = true;
                    const auto ping_time = ping_end - peer->m_ping_start.load();
                    if (ping_time.count() >= 0) {
                        // Let connman know about this successful ping-pong
                        pfrom.PongReceived(ping_time);
                    } else {
                        // This should never happen
                        sProblem = "Timing mishap";
                    }
                } else {
                    // Nonce mismatches are normal when pings are overlapping
                    sProblem = "Nonce mismatch";
                    if (nonce == 0) {
                        // This is most likely a bug in another implementation somewhere; cancel this ping
                        bPingFinished = true;
                        sProblem = "Nonce zero";
                    }
                }
            } else {
                sProblem = "Unsolicited pong without ping";
            }
        } else {
            // This is most likely a bug in another implementation somewhere; cancel this ping
            bPingFinished = true;
            sProblem = "Short payload";
        }

        if (!(sProblem.empty())) {
            LogPrint(BCLog::NET, "pong peer=%d: %s, %x expected, %x received, %u bytes\n",
                pfrom.GetId(),
                sProblem,
                peer->m_ping_nonce_sent,
                nonce,
                nAvail);
        }
        if (bPingFinished) {
            peer->m_ping_nonce_sent = 0;
        }
        return;
    }

    if (msg_type == NetMsgType::FILTERLOAD) {
        if (!(pfrom.GetLocalServices() & NODE_BLOOM)) {
            LogPrint(BCLog::NET, "filterload received despite not offering bloom services from peer=%d; disconnecting\n", pfrom.GetId());
            pfrom.fDisconnect = true;
            return;
        }
        CBloomFilter filter;
        vRecv >> filter;

        if (!filter.IsWithinSizeConstraints())
        {
            // There is no excuse for sending a too-large filter
            Misbehaving(pfrom.GetId(), 100, "too-large bloom filter");
        }
        else if (pfrom.m_tx_relay != nullptr)
        {
            LOCK(pfrom.m_tx_relay->cs_filter);
            pfrom.m_tx_relay->pfilter.reset(new CBloomFilter(filter));
            pfrom.m_tx_relay->fRelayTxes = true;
        }
        return;
    }

    if (msg_type == NetMsgType::FILTERADD) {
        if (!(pfrom.GetLocalServices() & NODE_BLOOM)) {
            LogPrint(BCLog::NET, "filteradd received despite not offering bloom services from peer=%d; disconnecting\n", pfrom.GetId());
            pfrom.fDisconnect = true;
            return;
        }
        std::vector<unsigned char> vData;
        vRecv >> vData;

        // Nodes must NEVER send a data item > 520 bytes (the max size for a script data object,
        // and thus, the maximum size any matched object can have) in a filteradd message
        bool bad = false;
        if (vData.size() > MAX_SCRIPT_ELEMENT_SIZE) {
            bad = true;
        } else if (pfrom.m_tx_relay != nullptr) {
            LOCK(pfrom.m_tx_relay->cs_filter);
            if (pfrom.m_tx_relay->pfilter) {
                pfrom.m_tx_relay->pfilter->insert(vData);
            } else {
                bad = true;
            }
        }
        if (bad) {
            Misbehaving(pfrom.GetId(), 100, "bad filteradd message");
        }
        return;
    }

    if (msg_type == NetMsgType::FILTERCLEAR) {
        if (!(pfrom.GetLocalServices() & NODE_BLOOM)) {
            LogPrint(BCLog::NET, "filterclear received despite not offering bloom services from peer=%d; disconnecting\n", pfrom.GetId());
            pfrom.fDisconnect = true;
            return;
        }
        if (pfrom.m_tx_relay == nullptr) {
            return;
        }
        LOCK(pfrom.m_tx_relay->cs_filter);
        pfrom.m_tx_relay->pfilter = nullptr;
        pfrom.m_tx_relay->fRelayTxes = true;
        return;
    }

    if (msg_type == NetMsgType::FEEFILTER) {
        CAmount newFeeFilter = 0;
        vRecv >> newFeeFilter;
        if (MoneyRange(newFeeFilter)) {
            if (pfrom.m_tx_relay != nullptr) {
                pfrom.m_tx_relay->minFeeFilter = newFeeFilter;
            }
            LogPrint(BCLog::NET, "received: feefilter of %s from peer=%d\n", CFeeRate(newFeeFilter).ToString(), pfrom.GetId());
        }
        return;
    }

    if (msg_type == NetMsgType::GETCFILTERS) {
        ProcessGetCFilters(pfrom, vRecv);
        return;
    }

    if (msg_type == NetMsgType::GETCFHEADERS) {
        ProcessGetCFHeaders(pfrom, vRecv);
        return;
    }

    if (msg_type == NetMsgType::GETCFCHECKPT) {
        ProcessGetCFCheckPt(pfrom, vRecv);
        return;
    }

    if (msg_type == NetMsgType::NOTFOUND) {
        std::vector<CInv> vInv;
        vRecv >> vInv;
        if (vInv.size() <= MAX_PEER_TX_ANNOUNCEMENTS + MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
            LOCK(::cs_main);
            for (CInv &inv : vInv) {
                if (inv.IsGenTxMsg()) {
                    // If we receive a NOTFOUND message for a tx we requested, mark the announcement for it as
                    // completed in TxRequestTracker.
                    m_txrequest.ReceivedResponse(pfrom.GetId(), inv.hash);
                }
            }
        }
        return;
    }

    // Ignore unknown commands for extensibility
    LogPrint(BCLog::NET, "Unknown command \"%s\" from peer=%d\n", SanitizeString(msg_type), pfrom.GetId());
    return;
}

bool PeerManagerImpl::MaybeDiscourageAndDisconnect(CNode& pnode, Peer& peer)
{
    {
        LOCK(peer.m_misbehavior_mutex);

        // There's nothing to do if the m_should_discourage flag isn't set
        if (!peer.m_should_discourage) return false;

        peer.m_should_discourage = false;
    } // peer.m_misbehavior_mutex

    if (pnode.HasPermission(NetPermissionFlags::NoBan)) {
        // We never disconnect or discourage peers for bad behavior if they have NetPermissionFlags::NoBan permission
        LogPrintf("Warning: not punishing noban peer %d!\n", peer.m_id);
        return false;
    }

    if (pnode.IsManualConn()) {
        // We never disconnect or discourage manual peers for bad behavior
        LogPrintf("Warning: not punishing manually connected peer %d!\n", peer.m_id);
        return false;
    }

    if (pnode.addr.IsLocal()) {
        // We disconnect local peers for bad behavior but don't discourage (since that would discourage
        // all peers on the same local address)
        LogPrint(BCLog::NET, "Warning: disconnecting but not discouraging %s peer %d!\n",
                 pnode.m_inbound_onion ? "inbound onion" : "local", peer.m_id);
        pnode.fDisconnect = true;
        return true;
    }

    // Normal case: Disconnect the peer and discourage all nodes sharing the address
    LogPrint(BCLog::NET, "Disconnecting and discouraging peer %d!\n", peer.m_id);
    if (m_banman) m_banman->Discourage(pnode.addr);
    m_connman.DisconnectNode(pnode.addr);
    return true;
}

bool PeerManagerImpl::ProcessMessages(CNode* pfrom, std::atomic<bool>& interruptMsgProc)
{
    bool fMoreWork = false;

    PeerRef peer = GetPeerRef(pfrom->GetId());
    if (peer == nullptr) return false;

    {
        LOCK(peer->m_getdata_requests_mutex);
        if (!peer->m_getdata_requests.empty()) {
            ProcessGetData(*pfrom, *peer, interruptMsgProc);
        }
    }

    {
        LOCK2(cs_main, g_cs_orphans);
        if (!peer->m_orphan_work_set.empty()) {
            ProcessOrphanTx(peer->m_orphan_work_set);
        }
    }

    if (pfrom->fDisconnect)
        return false;

    // this maintains the order of responses
    // and prevents m_getdata_requests to grow unbounded
    {
        LOCK(peer->m_getdata_requests_mutex);
        if (!peer->m_getdata_requests.empty()) return true;
    }

    {
        LOCK(g_cs_orphans);
        if (!peer->m_orphan_work_set.empty()) return true;
    }

    // Don't bother if send buffer is too full to respond anyway
    if (pfrom->fPauseSend) return false;

    std::list<CNetMessage> msgs;
    {
        LOCK(pfrom->cs_vProcessMsg);
        if (pfrom->vProcessMsg.empty()) return false;
        // Just take one message
        msgs.splice(msgs.begin(), pfrom->vProcessMsg, pfrom->vProcessMsg.begin());
        pfrom->nProcessQueueSize -= msgs.front().m_raw_message_size;
        pfrom->fPauseRecv = pfrom->nProcessQueueSize > m_connman.GetReceiveFloodSize();
        fMoreWork = !pfrom->vProcessMsg.empty();
    }
    CNetMessage& msg(msgs.front());

    TRACE6(net, inbound_message,
        pfrom->GetId(),
        pfrom->m_addr_name.c_str(),
        pfrom->ConnectionTypeAsString().c_str(),
        msg.m_command.c_str(),
        msg.m_recv.size(),
        msg.m_recv.data()
    );

    if (gArgs.GetBoolArg("-capturemessages", false)) {
        CaptureMessage(pfrom->addr, msg.m_command, MakeUCharSpan(msg.m_recv), /* incoming */ true);
    }

    msg.SetVersion(pfrom->GetCommonVersion());
    const std::string& msg_type = msg.m_command;

    // Message size
    unsigned int nMessageSize = msg.m_message_size;

    try {
        ProcessMessage(*pfrom, msg_type, msg.m_recv, msg.m_time, interruptMsgProc);
        if (interruptMsgProc) return false;
        {
            LOCK(peer->m_getdata_requests_mutex);
            if (!peer->m_getdata_requests.empty()) fMoreWork = true;
        }
    } catch (const std::exception& e) {
        LogPrint(BCLog::NET, "%s(%s, %u bytes): Exception '%s' (%s) caught\n", __func__, SanitizeString(msg_type), nMessageSize, e.what(), typeid(e).name());
    } catch (...) {
        LogPrint(BCLog::NET, "%s(%s, %u bytes): Unknown exception caught\n", __func__, SanitizeString(msg_type), nMessageSize);
    }

    return fMoreWork;
}

void PeerManagerImpl::ConsiderEviction(CNode& pto, int64_t time_in_seconds)
{
    AssertLockHeld(cs_main);

    CNodeState &state = *State(pto.GetId());
    const CNetMsgMaker msgMaker(pto.GetCommonVersion());

    if (!state.m_chain_sync.m_protect && pto.IsOutboundOrBlockRelayConn() && state.fSyncStarted) {
        // This is an outbound peer subject to disconnection if they don't
        // announce a block with as much work as the current tip within
        // CHAIN_SYNC_TIMEOUT + HEADERS_RESPONSE_TIME seconds (note: if
        // their chain has more work than ours, we should sync to it,
        // unless it's invalid, in which case we should find that out and
        // disconnect from them elsewhere).
        if (state.pindexBestKnownBlock != nullptr && state.pindexBestKnownBlock->nChainWork >= m_chainman.ActiveChain().Tip()->nChainWork) {
            if (state.m_chain_sync.m_timeout != 0) {
                state.m_chain_sync.m_timeout = 0;
                state.m_chain_sync.m_work_header = nullptr;
                state.m_chain_sync.m_sent_getheaders = false;
            }
        } else if (state.m_chain_sync.m_timeout == 0 || (state.m_chain_sync.m_work_header != nullptr && state.pindexBestKnownBlock != nullptr && state.pindexBestKnownBlock->nChainWork >= state.m_chain_sync.m_work_header->nChainWork)) {
            // Our best block known by this peer is behind our tip, and we're either noticing
            // that for the first time, OR this peer was able to catch up to some earlier point
            // where we checked against our tip.
            // Either way, set a new timeout based on current tip.
            state.m_chain_sync.m_timeout = time_in_seconds + CHAIN_SYNC_TIMEOUT;
            state.m_chain_sync.m_work_header = m_chainman.ActiveChain().Tip();
            state.m_chain_sync.m_sent_getheaders = false;
        } else if (state.m_chain_sync.m_timeout > 0 && time_in_seconds > state.m_chain_sync.m_timeout) {
            // No evidence yet that our peer has synced to a chain with work equal to that
            // of our tip, when we first detected it was behind. Send a single getheaders
            // message to give the peer a chance to update us.
            if (state.m_chain_sync.m_sent_getheaders) {
                // They've run out of time to catch up!
                LogPrintf("Disconnecting outbound peer %d for old chain, best known block = %s\n", pto.GetId(), state.pindexBestKnownBlock != nullptr ? state.pindexBestKnownBlock->GetBlockHash().ToString() : "<none>");
                pto.fDisconnect = true;
            } else {
                assert(state.m_chain_sync.m_work_header);
                LogPrint(BCLog::NET, "sending getheaders to outbound peer=%d to verify chain work (current best known block:%s, benchmark blockhash: %s)\n", pto.GetId(), state.pindexBestKnownBlock != nullptr ? state.pindexBestKnownBlock->GetBlockHash().ToString() : "<none>", state.m_chain_sync.m_work_header->GetBlockHash().ToString());
                m_connman.PushMessage(&pto, msgMaker.Make(NetMsgType::GETHEADERS, m_chainman.ActiveChain().GetLocator(state.m_chain_sync.m_work_header->pprev), uint256()));
                state.m_chain_sync.m_sent_getheaders = true;
                constexpr int64_t HEADERS_RESPONSE_TIME = 120; // 2 minutes
                // Bump the timeout to allow a response, which could clear the timeout
                // (if the response shows the peer has synced), reset the timeout (if
                // the peer syncs to the required work but not to our tip), or result
                // in disconnect (if we advance to the timeout and pindexBestKnownBlock
                // has not sufficiently progressed)
                state.m_chain_sync.m_timeout = time_in_seconds + HEADERS_RESPONSE_TIME;
            }
        }
    }
}

void PeerManagerImpl::EvictExtraOutboundPeers(int64_t time_in_seconds)
{
    // If we have any extra block-relay-only peers, disconnect the youngest unless
    // it's given us a block -- in which case, compare with the second-youngest, and
    // out of those two, disconnect the peer who least recently gave us a block.
    // The youngest block-relay-only peer would be the extra peer we connected
    // to temporarily in order to sync our tip; see net.cpp.
    // Note that we use higher nodeid as a measure for most recent connection.
    if (m_connman.GetExtraBlockRelayCount() > 0) {
        std::pair<NodeId, int64_t> youngest_peer{-1, 0}, next_youngest_peer{-1, 0};

        m_connman.ForEachNode([&](CNode* pnode) {
            if (!pnode->IsBlockOnlyConn() || pnode->fDisconnect) return;
            if (pnode->GetId() > youngest_peer.first) {
                next_youngest_peer = youngest_peer;
                youngest_peer.first = pnode->GetId();
                youngest_peer.second = pnode->nLastBlockTime;
            }
        });
        NodeId to_disconnect = youngest_peer.first;
        if (youngest_peer.second > next_youngest_peer.second) {
            // Our newest block-relay-only peer gave us a block more recently;
            // disconnect our second youngest.
            to_disconnect = next_youngest_peer.first;
        }
        m_connman.ForNode(to_disconnect, [&](CNode* pnode) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
            AssertLockHeld(::cs_main);
            // Make sure we're not getting a block right now, and that
            // we've been connected long enough for this eviction to happen
            // at all.
            // Note that we only request blocks from a peer if we learn of a
            // valid headers chain with at least as much work as our tip.
            CNodeState *node_state = State(pnode->GetId());
            if (node_state == nullptr ||
                (time_in_seconds - pnode->nTimeConnected >= MINIMUM_CONNECT_TIME && node_state->nBlocksInFlight == 0)) {
                pnode->fDisconnect = true;
                LogPrint(BCLog::NET, "disconnecting extra block-relay-only peer=%d (last block received at time %d)\n", pnode->GetId(), pnode->nLastBlockTime);
                return true;
            } else {
                LogPrint(BCLog::NET, "keeping block-relay-only peer=%d chosen for eviction (connect time: %d, blocks_in_flight: %d)\n",
                    pnode->GetId(), pnode->nTimeConnected, node_state->nBlocksInFlight);
            }
            return false;
        });
    }

    // Check whether we have too many outbound-full-relay peers
    if (m_connman.GetExtraFullOutboundCount() > 0) {
        // If we have more outbound-full-relay peers than we target, disconnect one.
        // Pick the outbound-full-relay peer that least recently announced
        // us a new block, with ties broken by choosing the more recent
        // connection (higher node id)
        NodeId worst_peer = -1;
        int64_t oldest_block_announcement = std::numeric_limits<int64_t>::max();

        m_connman.ForEachNode([&](CNode* pnode) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
            AssertLockHeld(::cs_main);

            // Only consider outbound-full-relay peers that are not already
            // marked for disconnection
            if (!pnode->IsFullOutboundConn() || pnode->fDisconnect) return;
            CNodeState *state = State(pnode->GetId());
            if (state == nullptr) return; // shouldn't be possible, but just in case
            // Don't evict our protected peers
            if (state->m_chain_sync.m_protect) return;
            if (state->m_last_block_announcement < oldest_block_announcement || (state->m_last_block_announcement == oldest_block_announcement && pnode->GetId() > worst_peer)) {
                worst_peer = pnode->GetId();
                oldest_block_announcement = state->m_last_block_announcement;
            }
        });
        if (worst_peer != -1) {
            bool disconnected = m_connman.ForNode(worst_peer, [&](CNode* pnode) EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
                AssertLockHeld(::cs_main);

                // Only disconnect a peer that has been connected to us for
                // some reasonable fraction of our check-frequency, to give
                // it time for new information to have arrived.
                // Also don't disconnect any peer we're trying to download a
                // block from.
                CNodeState &state = *State(pnode->GetId());
                if (time_in_seconds - pnode->nTimeConnected > MINIMUM_CONNECT_TIME && state.nBlocksInFlight == 0) {
                    LogPrint(BCLog::NET, "disconnecting extra outbound peer=%d (last block announcement received at time %d)\n", pnode->GetId(), oldest_block_announcement);
                    pnode->fDisconnect = true;
                    return true;
                } else {
                    LogPrint(BCLog::NET, "keeping outbound peer=%d chosen for eviction (connect time: %d, blocks_in_flight: %d)\n", pnode->GetId(), pnode->nTimeConnected, state.nBlocksInFlight);
                    return false;
                }
            });
            if (disconnected) {
                // If we disconnected an extra peer, that means we successfully
                // connected to at least one peer after the last time we
                // detected a stale tip. Don't try any more extra peers until
                // we next detect a stale tip, to limit the load we put on the
                // network from these extra connections.
                m_connman.SetTryNewOutboundPeer(false);
            }
        }
    }
}

void PeerManagerImpl::CheckForStaleTipAndEvictPeers()
{
    LOCK(cs_main);

    int64_t time_in_seconds = GetTime();

    EvictExtraOutboundPeers(time_in_seconds);

    if (time_in_seconds > m_stale_tip_check_time) {
        // Check whether our tip is stale, and if so, allow using an extra
        // outbound peer
        if (!fImporting && !fReindex && m_connman.GetNetworkActive() && m_connman.GetUseAddrmanOutgoing() && TipMayBeStale()) {
            LogPrintf("Potential stale tip detected, will try using extra outbound peer (last tip update: %d seconds ago)\n", time_in_seconds - m_last_tip_update);
            m_connman.SetTryNewOutboundPeer(true);
        } else if (m_connman.GetTryNewOutboundPeer()) {
            m_connman.SetTryNewOutboundPeer(false);
        }
        m_stale_tip_check_time = time_in_seconds + STALE_CHECK_INTERVAL;
    }

    if (!m_initial_sync_finished && CanDirectFetch()) {
        m_connman.StartExtraBlockRelayPeers();
        m_initial_sync_finished = true;
    }
}

void PeerManagerImpl::MaybeSendPing(CNode& node_to, Peer& peer, std::chrono::microseconds now)
{
    if (m_connman.ShouldRunInactivityChecks(node_to) && peer.m_ping_nonce_sent &&
        now > peer.m_ping_start.load() + std::chrono::seconds{TIMEOUT_INTERVAL}) {
        LogPrint(BCLog::NET, "ping timeout: %fs peer=%d\n", 0.000001 * count_microseconds(now - peer.m_ping_start.load()), peer.m_id);
        node_to.fDisconnect = true;
        return;
    }

    const CNetMsgMaker msgMaker(node_to.GetCommonVersion());
    bool pingSend = false;

    if (peer.m_ping_queued) {
        // RPC ping request by user
        pingSend = true;
    }

    if (peer.m_ping_nonce_sent == 0 && now > peer.m_ping_start.load() + PING_INTERVAL) {
        // Ping automatically sent as a latency probe & keepalive.
        pingSend = true;
    }

    if (pingSend) {
        uint64_t nonce = 0;
        while (nonce == 0) {
            GetRandBytes((unsigned char*)&nonce, sizeof(nonce));
        }
        peer.m_ping_queued = false;
        peer.m_ping_start = now;
        if (node_to.GetCommonVersion() > BIP0031_VERSION) {
            peer.m_ping_nonce_sent = nonce;
            m_connman.PushMessage(&node_to, msgMaker.Make(NetMsgType::PING, nonce));
        } else {
            // Peer is too old to support ping command with nonce, pong will never arrive.
            peer.m_ping_nonce_sent = 0;
            m_connman.PushMessage(&node_to, msgMaker.Make(NetMsgType::PING));
        }
    }
}

void PeerManagerImpl::MaybeSendAddr(CNode& node, Peer& peer, std::chrono::microseconds current_time)
{
    // Nothing to do for non-address-relay peers
    if (!peer.m_addr_relay_enabled) return;

    LOCK(peer.m_addr_send_times_mutex);
    // Periodically advertise our local address to the peer.
    if (fListen && !m_chainman.ActiveChainstate().IsInitialBlockDownload() &&
        peer.m_next_local_addr_send < current_time) {
        // If we've sent before, clear the bloom filter for the peer, so that our
        // self-announcement will actually go out.
        // This might be unnecessary if the bloom filter has already rolled
        // over since our last self-announcement, but there is only a small
        // bandwidth cost that we can incur by doing this (which happens
        // once a day on average).
        if (peer.m_next_local_addr_send != 0us) {
            peer.m_addr_known->reset();
        }
        if (std::optional<CAddress> local_addr = GetLocalAddrForPeer(&node)) {
            FastRandomContext insecure_rand;
            PushAddress(peer, *local_addr, insecure_rand);
        }
        peer.m_next_local_addr_send = PoissonNextSend(current_time, AVG_LOCAL_ADDRESS_BROADCAST_INTERVAL);
    }

    // We sent an `addr` message to this peer recently. Nothing more to do.
    if (current_time <= peer.m_next_addr_send) return;

    peer.m_next_addr_send = PoissonNextSend(current_time, AVG_ADDRESS_BROADCAST_INTERVAL);

    if (!Assume(peer.m_addrs_to_send.size() <= MAX_ADDR_TO_SEND)) {
        // Should be impossible since we always check size before adding to
        // m_addrs_to_send. Recover by trimming the vector.
        peer.m_addrs_to_send.resize(MAX_ADDR_TO_SEND);
    }

    // Remove addr records that the peer already knows about, and add new
    // addrs to the m_addr_known filter on the same pass.
    auto addr_already_known = [&peer](const CAddress& addr) {
        bool ret = peer.m_addr_known->contains(addr.GetKey());
        if (!ret) peer.m_addr_known->insert(addr.GetKey());
        return ret;
    };
    peer.m_addrs_to_send.erase(std::remove_if(peer.m_addrs_to_send.begin(), peer.m_addrs_to_send.end(), addr_already_known),
                           peer.m_addrs_to_send.end());

    // No addr messages to send
    if (peer.m_addrs_to_send.empty()) return;

    const char* msg_type;
    int make_flags;
    if (peer.m_wants_addrv2) {
        msg_type = NetMsgType::ADDRV2;
        make_flags = ADDRV2_FORMAT;
    } else {
        msg_type = NetMsgType::ADDR;
        make_flags = 0;
    }
    m_connman.PushMessage(&node, CNetMsgMaker(node.GetCommonVersion()).Make(make_flags, msg_type, peer.m_addrs_to_send));
    peer.m_addrs_to_send.clear();

    // we only send the big addr message once
    if (peer.m_addrs_to_send.capacity() > 40) {
        peer.m_addrs_to_send.shrink_to_fit();
    }
}

void PeerManagerImpl::MaybeSendFeefilter(CNode& pto, std::chrono::microseconds current_time)
{
    AssertLockHeld(cs_main);

    if (m_ignore_incoming_txs) return;
    if (!pto.m_tx_relay) return;
    if (pto.GetCommonVersion() < FEEFILTER_VERSION) return;
    // peers with the forcerelay permission should not filter txs to us
    if (pto.HasPermission(NetPermissionFlags::ForceRelay)) return;

    CAmount currentFilter = m_mempool.GetMinFee(gArgs.GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFeePerK();
    static FeeFilterRounder g_filter_rounder{CFeeRate{DEFAULT_MIN_RELAY_TX_FEE}};

    if (m_chainman.ActiveChainstate().IsInitialBlockDownload()) {
        // Received tx-inv messages are discarded when the active
        // chainstate is in IBD, so tell the peer to not send them.
        currentFilter = MAX_MONEY;
    } else {
        static const CAmount MAX_FILTER{g_filter_rounder.round(MAX_MONEY)};
        if (pto.m_tx_relay->lastSentFeeFilter == MAX_FILTER) {
            // Send the current filter if we sent MAX_FILTER previously
            // and made it out of IBD.
            pto.m_tx_relay->m_next_send_feefilter = 0us;
        }
    }
    if (current_time > pto.m_tx_relay->m_next_send_feefilter) {
        CAmount filterToSend = g_filter_rounder.round(currentFilter);
        // We always have a fee filter of at least minRelayTxFee
        filterToSend = std::max(filterToSend, ::minRelayTxFee.GetFeePerK());
        if (filterToSend != pto.m_tx_relay->lastSentFeeFilter) {
            m_connman.PushMessage(&pto, CNetMsgMaker(pto.GetCommonVersion()).Make(NetMsgType::FEEFILTER, filterToSend));
            pto.m_tx_relay->lastSentFeeFilter = filterToSend;
        }
        pto.m_tx_relay->m_next_send_feefilter = PoissonNextSend(current_time, AVG_FEEFILTER_BROADCAST_INTERVAL);
    }
    // If the fee filter has changed substantially and it's still more than MAX_FEEFILTER_CHANGE_DELAY
    // until scheduled broadcast, then move the broadcast to within MAX_FEEFILTER_CHANGE_DELAY.
    else if (current_time + MAX_FEEFILTER_CHANGE_DELAY < pto.m_tx_relay->m_next_send_feefilter &&
                (currentFilter < 3 * pto.m_tx_relay->lastSentFeeFilter / 4 || currentFilter > 4 * pto.m_tx_relay->lastSentFeeFilter / 3)) {
        pto.m_tx_relay->m_next_send_feefilter = current_time + GetRandomDuration<std::chrono::microseconds>(MAX_FEEFILTER_CHANGE_DELAY);
    }
}

namespace {
class CompareInvMempoolOrder
{
    CTxMemPool *mp;
    bool m_wtxid_relay;
public:
    explicit CompareInvMempoolOrder(CTxMemPool *_mempool, bool use_wtxid)
    {
        mp = _mempool;
        m_wtxid_relay = use_wtxid;
    }

    bool operator()(std::set<uint256>::iterator a, std::set<uint256>::iterator b)
    {
        /* As std::make_heap produces a max-heap, we want the entries with the
         * fewest ancestors/highest fee to sort later. */
        return mp->CompareDepthAndScore(*b, *a, m_wtxid_relay);
    }
};
}

bool PeerManagerImpl::SetupAddressRelay(const CNode& node, Peer& peer)
{
    // We don't participate in addr relay with outbound block-relay-only
    // connections to prevent providing adversaries with the additional
    // information of addr traffic to infer the link.
    if (node.IsBlockOnlyConn()) return false;

    if (!peer.m_addr_relay_enabled.exchange(true)) {
        // First addr message we have received from the peer, initialize
        // m_addr_known
        peer.m_addr_known = std::make_unique<CRollingBloomFilter>(5000, 0.001);
    }

    return true;
}

bool PeerManagerImpl::SendMessages(CNode* pto)
{
    PeerRef peer = GetPeerRef(pto->GetId());
    if (!peer) return false;
    const Consensus::Params& consensusParams = m_chainparams.GetConsensus();

    // We must call MaybeDiscourageAndDisconnect first, to ensure that we'll
    // disconnect misbehaving peers even before the version handshake is complete.
    if (MaybeDiscourageAndDisconnect(*pto, *peer)) return true;

    // Don't send anything until the version handshake is complete
    if (!pto->fSuccessfullyConnected || pto->fDisconnect)
        return true;

    // If we get here, the outgoing message serialization version is set and can't change.
    const CNetMsgMaker msgMaker(pto->GetCommonVersion());

    const auto current_time = GetTime<std::chrono::microseconds>();

    if (pto->IsAddrFetchConn() && current_time - std::chrono::seconds(pto->nTimeConnected) > 10 * AVG_ADDRESS_BROADCAST_INTERVAL) {
        LogPrint(BCLog::NET, "addrfetch connection timeout; disconnecting peer=%d\n", pto->GetId());
        pto->fDisconnect = true;
        return true;
    }

    MaybeSendPing(*pto, *peer, current_time);

    // MaybeSendPing may have marked peer for disconnection
    if (pto->fDisconnect) return true;

    MaybeSendAddr(*pto, *peer, current_time);

    {
        LOCK(cs_main);

        CNodeState &state = *State(pto->GetId());

        // Start block sync
        if (pindexBestHeader == nullptr)
            pindexBestHeader = m_chainman.ActiveChain().Tip();
        bool fFetch = state.fPreferredDownload || (nPreferredDownload == 0 && !pto->fClient && !pto->IsAddrFetchConn()); // Download if this is a nice peer, or we have no nice peers and this one might do.
        if (!state.fSyncStarted && !pto->fClient && !fImporting && !fReindex) {
            // Only actively request headers from a single peer, unless we're close to today.
            if ((nSyncStarted == 0 && fFetch) || pindexBestHeader->GetBlockTime() > GetAdjustedTime() - 24 * 60 * 60) {
                state.fSyncStarted = true;
                state.m_headers_sync_timeout = current_time + HEADERS_DOWNLOAD_TIMEOUT_BASE +
                    (
                        // Convert HEADERS_DOWNLOAD_TIMEOUT_PER_HEADER to microseconds before scaling
                        // to maintain precision
                        std::chrono::microseconds{HEADERS_DOWNLOAD_TIMEOUT_PER_HEADER} *
                        (GetAdjustedTime() - pindexBestHeader->GetBlockTime()) / consensusParams.nPowTargetSpacing
                    );
                nSyncStarted++;
                const CBlockIndex *pindexStart = pindexBestHeader;
                /* If possible, start at the block preceding the currently
                   best known header.  This ensures that we always get a
                   non-empty list of headers back as long as the peer
                   is up-to-date.  With a non-empty response, we can initialise
                   the peer's known best block.  This wouldn't be possible
                   if we requested starting at pindexBestHeader and
                   got back an empty response.  */
                if (pindexStart->pprev)
                    pindexStart = pindexStart->pprev;
                LogPrint(BCLog::NET, "initial getheaders (%d) to peer=%d (startheight:%d)\n", pindexStart->nHeight, pto->GetId(), peer->m_starting_height);
                m_connman.PushMessage(pto, msgMaker.Make(NetMsgType::GETHEADERS, m_chainman.ActiveChain().GetLocator(pindexStart), uint256()));
            }
        }

        //
        // Try sending block announcements via headers
        //
        {
            // If we have less than MAX_BLOCKS_TO_ANNOUNCE in our
            // list of block hashes we're relaying, and our peer wants
            // headers announcements, then find the first header
            // not yet known to our peer but would connect, and send.
            // If no header would connect, or if we have too many
            // blocks, or if the peer doesn't want headers, just
            // add all to the inv queue.
            LOCK(peer->m_block_inv_mutex);
            std::vector<CBlock> vHeaders;
            bool fRevertToInv = ((!state.fPreferHeaders &&
                                 (!state.fPreferHeaderAndIDs || peer->m_blocks_for_headers_relay.size() > 1)) ||
                                 peer->m_blocks_for_headers_relay.size() > MAX_BLOCKS_TO_ANNOUNCE);
            const CBlockIndex *pBestIndex = nullptr; // last header queued for delivery
            ProcessBlockAvailability(pto->GetId()); // ensure pindexBestKnownBlock is up-to-date

            if (!fRevertToInv) {
                bool fFoundStartingHeader = false;
                // Try to find first header that our peer doesn't have, and
                // then send all headers past that one.  If we come across any
                // headers that aren't on m_chainman.ActiveChain(), give up.
                for (const uint256& hash : peer->m_blocks_for_headers_relay) {
                    const CBlockIndex* pindex = m_chainman.m_blockman.LookupBlockIndex(hash);
                    assert(pindex);
                    if (m_chainman.ActiveChain()[pindex->nHeight] != pindex) {
                        // Bail out if we reorged away from this block
                        fRevertToInv = true;
                        break;
                    }
                    if (pBestIndex != nullptr && pindex->pprev != pBestIndex) {
                        // This means that the list of blocks to announce don't
                        // connect to each other.
                        // This shouldn't really be possible to hit during
                        // regular operation (because reorgs should take us to
                        // a chain that has some block not on the prior chain,
                        // which should be caught by the prior check), but one
                        // way this could happen is by using invalidateblock /
                        // reconsiderblock repeatedly on the tip, causing it to
                        // be added multiple times to m_blocks_for_headers_relay.
                        // Robustly deal with this rare situation by reverting
                        // to an inv.
                        fRevertToInv = true;
                        break;
                    }
                    pBestIndex = pindex;
                    if (fFoundStartingHeader) {
                        // add this to the headers message
                        vHeaders.push_back(pindex->GetBlockHeader());
                    } else if (PeerHasHeader(&state, pindex)) {
                        continue; // keep looking for the first new block
                    } else if (pindex->pprev == nullptr || PeerHasHeader(&state, pindex->pprev)) {
                        // Peer doesn't have this header but they do have the prior one.
                        // Start sending headers.
                        fFoundStartingHeader = true;
                        vHeaders.push_back(pindex->GetBlockHeader());
                    } else {
                        // Peer doesn't have this header or the prior one -- nothing will
                        // connect, so bail out.
                        fRevertToInv = true;
                        break;
                    }
                }
            }
            if (!fRevertToInv && !vHeaders.empty()) {
                if (vHeaders.size() == 1 && state.fPreferHeaderAndIDs) {
                    // We only send up to 1 block as header-and-ids, as otherwise
                    // probably means we're doing an initial-ish-sync or they're slow
                    LogPrint(BCLog::NET, "%s sending header-and-ids %s to peer=%d\n", __func__,
                            vHeaders.front().GetHash().ToString(), pto->GetId());

                    int nSendFlags = state.fWantsCmpctWitness ? 0 : SERIALIZE_TRANSACTION_NO_WITNESS;

                    bool fGotBlockFromCache = false;
                    {
                        LOCK(cs_most_recent_block);
                        if (most_recent_block_hash == pBestIndex->GetBlockHash()) {
                            if (state.fWantsCmpctWitness || !fWitnessesPresentInMostRecentCompactBlock)
                                m_connman.PushMessage(pto, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, *most_recent_compact_block));
                            else {
                                CBlockHeaderAndShortTxIDs cmpctblock(*most_recent_block, state.fWantsCmpctWitness);
                                m_connman.PushMessage(pto, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, cmpctblock));
                            }
                            fGotBlockFromCache = true;
                        }
                    }
                    if (!fGotBlockFromCache) {
                        CBlock block;
                        bool ret = ReadBlockFromDisk(block, pBestIndex, consensusParams);
                        assert(ret);
                        CBlockHeaderAndShortTxIDs cmpctblock(block, state.fWantsCmpctWitness);
                        m_connman.PushMessage(pto, msgMaker.Make(nSendFlags, NetMsgType::CMPCTBLOCK, cmpctblock));
                    }
                    state.pindexBestHeaderSent = pBestIndex;
                } else if (state.fPreferHeaders) {
                    if (vHeaders.size() > 1) {
                        LogPrint(BCLog::NET, "%s: %u headers, range (%s, %s), to peer=%d\n", __func__,
                                vHeaders.size(),
                                vHeaders.front().GetHash().ToString(),
                                vHeaders.back().GetHash().ToString(), pto->GetId());
                    } else {
                        LogPrint(BCLog::NET, "%s: sending header %s to peer=%d\n", __func__,
                                vHeaders.front().GetHash().ToString(), pto->GetId());
                    }
                    m_connman.PushMessage(pto, msgMaker.Make(NetMsgType::HEADERS, vHeaders));
                    state.pindexBestHeaderSent = pBestIndex;
                } else
                    fRevertToInv = true;
            }
            if (fRevertToInv) {
                // If falling back to using an inv, just try to inv the tip.
                // The last entry in m_blocks_for_headers_relay was our tip at some point
                // in the past.
                if (!peer->m_blocks_for_headers_relay.empty()) {
                    const uint256& hashToAnnounce = peer->m_blocks_for_headers_relay.back();
                    const CBlockIndex* pindex = m_chainman.m_blockman.LookupBlockIndex(hashToAnnounce);
                    assert(pindex);

                    // Warn if we're announcing a block that is not on the main chain.
                    // This should be very rare and could be optimized out.
                    // Just log for now.
                    if (m_chainman.ActiveChain()[pindex->nHeight] != pindex) {
                        LogPrint(BCLog::NET, "Announcing block %s not on main chain (tip=%s)\n",
                            hashToAnnounce.ToString(), m_chainman.ActiveChain().Tip()->GetBlockHash().ToString());
                    }

                    // If the peer's chain has this block, don't inv it back.
                    if (!PeerHasHeader(&state, pindex)) {
                        peer->m_blocks_for_inv_relay.push_back(hashToAnnounce);
                        LogPrint(BCLog::NET, "%s: sending inv peer=%d hash=%s\n", __func__,
                            pto->GetId(), hashToAnnounce.ToString());
                    }
                }
            }
            peer->m_blocks_for_headers_relay.clear();
        }

        //
        // Message: inventory
        //
        std::vector<CInv> vInv;
        {
            LOCK(peer->m_block_inv_mutex);
            vInv.reserve(std::max<size_t>(peer->m_blocks_for_inv_relay.size(), INVENTORY_BROADCAST_MAX));

            // Add blocks
            for (const uint256& hash : peer->m_blocks_for_inv_relay) {
                vInv.push_back(CInv(MSG_BLOCK, hash));
                if (vInv.size() == MAX_INV_SZ) {
                    m_connman.PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));
                    vInv.clear();
                }
            }
            peer->m_blocks_for_inv_relay.clear();
        }

        if (pto->m_tx_relay != nullptr) {
                LOCK(pto->m_tx_relay->cs_tx_inventory);
                // Check whether periodic sends should happen
                bool fSendTrickle = pto->HasPermission(NetPermissionFlags::NoBan);
                if (pto->m_tx_relay->nNextInvSend < current_time) {
                    fSendTrickle = true;
                    if (pto->IsInboundConn()) {
                        pto->m_tx_relay->nNextInvSend = m_connman.PoissonNextSendInbound(current_time, INBOUND_INVENTORY_BROADCAST_INTERVAL);
                    } else {
                        pto->m_tx_relay->nNextInvSend = PoissonNextSend(current_time, OUTBOUND_INVENTORY_BROADCAST_INTERVAL);
                    }
                }

                // Time to send but the peer has requested we not relay transactions.
                if (fSendTrickle) {
                    LOCK(pto->m_tx_relay->cs_filter);
                    if (!pto->m_tx_relay->fRelayTxes) pto->m_tx_relay->setInventoryTxToSend.clear();
                }

                // Respond to BIP35 mempool requests
                if (fSendTrickle && pto->m_tx_relay->fSendMempool) {
                    auto vtxinfo = m_mempool.infoAll();
                    pto->m_tx_relay->fSendMempool = false;
                    const CFeeRate filterrate{pto->m_tx_relay->minFeeFilter.load()};

                    LOCK(pto->m_tx_relay->cs_filter);

                    for (const auto& txinfo : vtxinfo) {
                        const uint256& hash = state.m_wtxid_relay ? txinfo.tx->GetWitnessHash() : txinfo.tx->GetHash();
                        CInv inv(state.m_wtxid_relay ? MSG_WTX : MSG_TX, hash);
                        pto->m_tx_relay->setInventoryTxToSend.erase(hash);
                        // Don't send transactions that peers will not put into their mempool
                        if (txinfo.fee < filterrate.GetFee(txinfo.vsize)) {
                            continue;
                        }
                        if (pto->m_tx_relay->pfilter) {
                            if (!pto->m_tx_relay->pfilter->IsRelevantAndUpdate(*txinfo.tx)) continue;
                        }
                        pto->m_tx_relay->filterInventoryKnown.insert(hash);
                        // Responses to MEMPOOL requests bypass the m_recently_announced_invs filter.
                        vInv.push_back(inv);
                        if (vInv.size() == MAX_INV_SZ) {
                            m_connman.PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));
                            vInv.clear();
                        }
                    }
                    pto->m_tx_relay->m_last_mempool_req = std::chrono::duration_cast<std::chrono::seconds>(current_time);
                }

                // Determine transactions to relay
                if (fSendTrickle) {
                    // Produce a vector with all candidates for sending
                    std::vector<std::set<uint256>::iterator> vInvTx;
                    vInvTx.reserve(pto->m_tx_relay->setInventoryTxToSend.size());
                    for (std::set<uint256>::iterator it = pto->m_tx_relay->setInventoryTxToSend.begin(); it != pto->m_tx_relay->setInventoryTxToSend.end(); it++) {
                        vInvTx.push_back(it);
                    }
                    const CFeeRate filterrate{pto->m_tx_relay->minFeeFilter.load()};
                    // Topologically and fee-rate sort the inventory we send for privacy and priority reasons.
                    // A heap is used so that not all items need sorting if only a few are being sent.
                    CompareInvMempoolOrder compareInvMempoolOrder(&m_mempool, state.m_wtxid_relay);
                    std::make_heap(vInvTx.begin(), vInvTx.end(), compareInvMempoolOrder);
                    // No reason to drain out at many times the network's capacity,
                    // especially since we have many peers and some will draw much shorter delays.
                    unsigned int nRelayedTransactions = 0;
                    LOCK(pto->m_tx_relay->cs_filter);
                    while (!vInvTx.empty() && nRelayedTransactions < INVENTORY_BROADCAST_MAX) {
                        // Fetch the top element from the heap
                        std::pop_heap(vInvTx.begin(), vInvTx.end(), compareInvMempoolOrder);
                        std::set<uint256>::iterator it = vInvTx.back();
                        vInvTx.pop_back();
                        uint256 hash = *it;
                        CInv inv(state.m_wtxid_relay ? MSG_WTX : MSG_TX, hash);
                        // Remove it from the to-be-sent set
                        pto->m_tx_relay->setInventoryTxToSend.erase(it);
                        // Check if not in the filter already
                        if (pto->m_tx_relay->filterInventoryKnown.contains(hash)) {
                            continue;
                        }
                        // Not in the mempool anymore? don't bother sending it.
                        auto txinfo = m_mempool.info(ToGenTxid(inv));
                        if (!txinfo.tx) {
                            continue;
                        }
                        auto txid = txinfo.tx->GetHash();
                        auto wtxid = txinfo.tx->GetWitnessHash();
                        // Peer told you to not send transactions at that feerate? Don't bother sending it.
                        if (txinfo.fee < filterrate.GetFee(txinfo.vsize)) {
                            continue;
                        }
                        if (pto->m_tx_relay->pfilter && !pto->m_tx_relay->pfilter->IsRelevantAndUpdate(*txinfo.tx)) continue;
                        // Send
                        State(pto->GetId())->m_recently_announced_invs.insert(hash);
                        vInv.push_back(inv);
                        nRelayedTransactions++;
                        {
                            // Expire old relay messages
                            while (!g_relay_expiration.empty() && g_relay_expiration.front().first < current_time)
                            {
                                mapRelay.erase(g_relay_expiration.front().second);
                                g_relay_expiration.pop_front();
                            }

                            auto ret = mapRelay.emplace(txid, std::move(txinfo.tx));
                            if (ret.second) {
                                g_relay_expiration.emplace_back(current_time + RELAY_TX_CACHE_TIME, ret.first);
                            }
                            // Add wtxid-based lookup into mapRelay as well, so that peers can request by wtxid
                            auto ret2 = mapRelay.emplace(wtxid, ret.first->second);
                            if (ret2.second) {
                                g_relay_expiration.emplace_back(current_time + RELAY_TX_CACHE_TIME, ret2.first);
                            }
                        }
                        if (vInv.size() == MAX_INV_SZ) {
                            m_connman.PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));
                            vInv.clear();
                        }
                        pto->m_tx_relay->filterInventoryKnown.insert(hash);
                        if (hash != txid) {
                            // Insert txid into filterInventoryKnown, even for
                            // wtxidrelay peers. This prevents re-adding of
                            // unconfirmed parents to the recently_announced
                            // filter, when a child tx is requested. See
                            // ProcessGetData().
                            pto->m_tx_relay->filterInventoryKnown.insert(txid);
                        }
                    }
                }
        }
        if (!vInv.empty())
            m_connman.PushMessage(pto, msgMaker.Make(NetMsgType::INV, vInv));

        // Detect whether we're stalling
        if (state.m_stalling_since.count() && state.m_stalling_since < current_time - BLOCK_STALLING_TIMEOUT) {
            // Stalling only triggers when the block download window cannot move. During normal steady state,
            // the download window should be much larger than the to-be-downloaded set of blocks, so disconnection
            // should only happen during initial block download.
            LogPrintf("Peer=%d is stalling block download, disconnecting\n", pto->GetId());
            pto->fDisconnect = true;
            return true;
        }
        // In case there is a block that has been in flight from this peer for block_interval * (1 + 0.5 * N)
        // (with N the number of peers from which we're downloading validated blocks), disconnect due to timeout.
        // We compensate for other peers to prevent killing off peers due to our own downstream link
        // being saturated. We only count validated in-flight blocks so peers can't advertise non-existing block hashes
        // to unreasonably increase our timeout.
        if (state.vBlocksInFlight.size() > 0) {
            QueuedBlock &queuedBlock = state.vBlocksInFlight.front();
            int nOtherPeersWithValidatedDownloads = m_peers_downloading_from - 1;
            if (current_time > state.m_downloading_since + std::chrono::seconds{consensusParams.nPowTargetSpacing} * (BLOCK_DOWNLOAD_TIMEOUT_BASE + BLOCK_DOWNLOAD_TIMEOUT_PER_PEER * nOtherPeersWithValidatedDownloads)) {
                LogPrintf("Timeout downloading block %s from peer=%d, disconnecting\n", queuedBlock.pindex->GetBlockHash().ToString(), pto->GetId());
                pto->fDisconnect = true;
                return true;
            }
        }
        // Check for headers sync timeouts
        if (state.fSyncStarted && state.m_headers_sync_timeout < std::chrono::microseconds::max()) {
            // Detect whether this is a stalling initial-headers-sync peer
            if (pindexBestHeader->GetBlockTime() <= GetAdjustedTime() - 24 * 60 * 60) {
                if (current_time > state.m_headers_sync_timeout && nSyncStarted == 1 && (nPreferredDownload - state.fPreferredDownload >= 1)) {
                    // Disconnect a peer (without NetPermissionFlags::NoBan permission) if it is our only sync peer,
                    // and we have others we could be using instead.
                    // Note: If all our peers are inbound, then we won't
                    // disconnect our sync peer for stalling; we have bigger
                    // problems if we can't get any outbound peers.
                    if (!pto->HasPermission(NetPermissionFlags::NoBan)) {
                        LogPrintf("Timeout downloading headers from peer=%d, disconnecting\n", pto->GetId());
                        pto->fDisconnect = true;
                        return true;
                    } else {
                        LogPrintf("Timeout downloading headers from noban peer=%d, not disconnecting\n", pto->GetId());
                        // Reset the headers sync state so that we have a
                        // chance to try downloading from a different peer.
                        // Note: this will also result in at least one more
                        // getheaders message to be sent to
                        // this peer (eventually).
                        state.fSyncStarted = false;
                        nSyncStarted--;
                        state.m_headers_sync_timeout = 0us;
                    }
                }
            } else {
                // After we've caught up once, reset the timeout so we can't trigger
                // disconnect later.
                state.m_headers_sync_timeout = std::chrono::microseconds::max();
            }
        }

        // Check that outbound peers have reasonable chains
        // GetTime() is used by this anti-DoS logic so we can test this using mocktime
        ConsiderEviction(*pto, GetTime());

        //
        // Message: getdata (blocks)
        //
        std::vector<CInv> vGetData;
        if (!pto->fClient && ((fFetch && !pto->m_limited_node) || !m_chainman.ActiveChainstate().IsInitialBlockDownload()) && state.nBlocksInFlight < MAX_BLOCKS_IN_TRANSIT_PER_PEER) {
            std::vector<const CBlockIndex*> vToDownload;
            NodeId staller = -1;
            FindNextBlocksToDownload(pto->GetId(), MAX_BLOCKS_IN_TRANSIT_PER_PEER - state.nBlocksInFlight, vToDownload, staller);
            for (const CBlockIndex *pindex : vToDownload) {
                uint32_t nFetchFlags = GetFetchFlags(*pto);
                vGetData.push_back(CInv(MSG_BLOCK | nFetchFlags, pindex->GetBlockHash()));
                BlockRequested(pto->GetId(), *pindex);
                LogPrint(BCLog::NET, "Requesting block %s (%d) peer=%d\n", pindex->GetBlockHash().ToString(),
                    pindex->nHeight, pto->GetId());
            }
            if (state.nBlocksInFlight == 0 && staller != -1) {
                if (State(staller)->m_stalling_since == 0us) {
                    State(staller)->m_stalling_since = current_time;
                    LogPrint(BCLog::NET, "Stall started peer=%d\n", staller);
                }
            }
        }

        //
        // Message: getdata (transactions)
        //
        std::vector<std::pair<NodeId, GenTxid>> expired;
        auto requestable = m_txrequest.GetRequestable(pto->GetId(), current_time, &expired);
        for (const auto& entry : expired) {
            LogPrint(BCLog::NET, "timeout of inflight %s %s from peer=%d\n", entry.second.IsWtxid() ? "wtx" : "tx",
                entry.second.GetHash().ToString(), entry.first);
        }
        for (const GenTxid& gtxid : requestable) {
            if (!AlreadyHaveTx(gtxid)) {
                LogPrint(BCLog::NET, "Requesting %s %s peer=%d\n", gtxid.IsWtxid() ? "wtx" : "tx",
                    gtxid.GetHash().ToString(), pto->GetId());
                vGetData.emplace_back(gtxid.IsWtxid() ? MSG_WTX : (MSG_TX | GetFetchFlags(*pto)), gtxid.GetHash());
                if (vGetData.size() >= MAX_GETDATA_SZ) {
                    m_connman.PushMessage(pto, msgMaker.Make(NetMsgType::GETDATA, vGetData));
                    vGetData.clear();
                }
                m_txrequest.RequestedTx(pto->GetId(), gtxid.GetHash(), current_time + GETDATA_TX_INTERVAL);
            } else {
                // We have already seen this transaction, no need to download. This is just a belt-and-suspenders, as
                // this should already be called whenever a transaction becomes AlreadyHaveTx().
                m_txrequest.ForgetTxHash(gtxid.GetHash());
            }
        }


        if (!vGetData.empty())
            m_connman.PushMessage(pto, msgMaker.Make(NetMsgType::GETDATA, vGetData));

        MaybeSendFeefilter(*pto, current_time);
    } // release cs_main
    return true;
}