aboutsummaryrefslogtreecommitdiff
path: root/src/net.cpp
blob: e1206745a425d815bb97614e3820e4070b52c3e0 (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
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2022 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 <config/bitcoin-config.h> // IWYU pragma: keep

#include <net.h>

#include <addrdb.h>
#include <addrman.h>
#include <banman.h>
#include <clientversion.h>
#include <common/args.h>
#include <compat/compat.h>
#include <consensus/consensus.h>
#include <crypto/sha256.h>
#include <i2p.h>
#include <key.h>
#include <logging.h>
#include <memusage.h>
#include <net_permissions.h>
#include <netaddress.h>
#include <netbase.h>
#include <node/eviction.h>
#include <node/interface_ui.h>
#include <protocol.h>
#include <random.h>
#include <scheduler.h>
#include <util/fs.h>
#include <util/sock.h>
#include <util/strencodings.h>
#include <util/thread.h>
#include <util/threadinterrupt.h>
#include <util/trace.h>
#include <util/translation.h>
#include <util/vector.h>

#ifdef WIN32
#include <string.h>
#endif

#if HAVE_DECL_GETIFADDRS && HAVE_DECL_FREEIFADDRS
#include <ifaddrs.h>
#endif

#include <algorithm>
#include <array>
#include <cstdint>
#include <functional>
#include <optional>
#include <unordered_map>

#include <math.h>

/** Maximum number of block-relay-only anchor connections */
static constexpr size_t MAX_BLOCK_RELAY_ONLY_ANCHORS = 2;
static_assert (MAX_BLOCK_RELAY_ONLY_ANCHORS <= static_cast<size_t>(MAX_BLOCK_RELAY_ONLY_CONNECTIONS), "MAX_BLOCK_RELAY_ONLY_ANCHORS must not exceed MAX_BLOCK_RELAY_ONLY_CONNECTIONS.");
/** Anchor IP address database file name */
const char* const ANCHORS_DATABASE_FILENAME = "anchors.dat";

// How often to dump addresses to peers.dat
static constexpr std::chrono::minutes DUMP_PEERS_INTERVAL{15};

/** Number of DNS seeds to query when the number of connections is low. */
static constexpr int DNSSEEDS_TO_QUERY_AT_ONCE = 3;

/** How long to delay before querying DNS seeds
 *
 * If we have more than THRESHOLD entries in addrman, then it's likely
 * that we got those addresses from having previously connected to the P2P
 * network, and that we'll be able to successfully reconnect to the P2P
 * network via contacting one of them. So if that's the case, spend a
 * little longer trying to connect to known peers before querying the
 * DNS seeds.
 */
static constexpr std::chrono::seconds DNSSEEDS_DELAY_FEW_PEERS{11};
static constexpr std::chrono::minutes DNSSEEDS_DELAY_MANY_PEERS{5};
static constexpr int DNSSEEDS_DELAY_PEER_THRESHOLD = 1000; // "many" vs "few" peers

/** The default timeframe for -maxuploadtarget. 1 day. */
static constexpr std::chrono::seconds MAX_UPLOAD_TIMEFRAME{60 * 60 * 24};

// A random time period (0 to 1 seconds) is added to feeler connections to prevent synchronization.
static constexpr auto FEELER_SLEEP_WINDOW{1s};

/** Frequency to attempt extra connections to reachable networks we're not connected to yet **/
static constexpr auto EXTRA_NETWORK_PEER_INTERVAL{5min};

/** Used to pass flags to the Bind() function */
enum BindFlags {
    BF_NONE         = 0,
    BF_REPORT_ERROR = (1U << 0),
    /**
     * Do not call AddLocal() for our special addresses, e.g., for incoming
     * Tor connections, to prevent gossiping them over the network.
     */
    BF_DONT_ADVERTISE = (1U << 1),
};

// The set of sockets cannot be modified while waiting
// The sleep time needs to be small to avoid new sockets stalling
static const uint64_t SELECT_TIMEOUT_MILLISECONDS = 50;

const std::string NET_MESSAGE_TYPE_OTHER = "*other*";

static const uint64_t RANDOMIZER_ID_NETGROUP = 0x6c0edd8036ef4036ULL; // SHA256("netgroup")[0:8]
static const uint64_t RANDOMIZER_ID_LOCALHOSTNONCE = 0xd93e69e2bbfa5735ULL; // SHA256("localhostnonce")[0:8]
static const uint64_t RANDOMIZER_ID_ADDRCACHE = 0x1cf2e4ddd306dda9ULL; // SHA256("addrcache")[0:8]
//
// Global state variables
//
bool fDiscover = true;
bool fListen = true;
GlobalMutex g_maplocalhost_mutex;
std::map<CNetAddr, LocalServiceInfo> mapLocalHost GUARDED_BY(g_maplocalhost_mutex);
std::string strSubVersion;

size_t CSerializedNetMsg::GetMemoryUsage() const noexcept
{
    // Don't count the dynamic memory used for the m_type string, by assuming it fits in the
    // "small string" optimization area (which stores data inside the object itself, up to some
    // size; 15 bytes in modern libstdc++).
    return sizeof(*this) + memusage::DynamicUsage(data);
}

void CConnman::AddAddrFetch(const std::string& strDest)
{
    LOCK(m_addr_fetches_mutex);
    m_addr_fetches.push_back(strDest);
}

uint16_t GetListenPort()
{
    // If -bind= is provided with ":port" part, use that (first one if multiple are provided).
    for (const std::string& bind_arg : gArgs.GetArgs("-bind")) {
        constexpr uint16_t dummy_port = 0;

        const std::optional<CService> bind_addr{Lookup(bind_arg, dummy_port, /*fAllowLookup=*/false)};
        if (bind_addr.has_value() && bind_addr->GetPort() != dummy_port) return bind_addr->GetPort();
    }

    // Otherwise, if -whitebind= without NetPermissionFlags::NoBan is provided, use that
    // (-whitebind= is required to have ":port").
    for (const std::string& whitebind_arg : gArgs.GetArgs("-whitebind")) {
        NetWhitebindPermissions whitebind;
        bilingual_str error;
        if (NetWhitebindPermissions::TryParse(whitebind_arg, whitebind, error)) {
            if (!NetPermissions::HasFlag(whitebind.m_flags, NetPermissionFlags::NoBan)) {
                return whitebind.m_service.GetPort();
            }
        }
    }

    // Otherwise, if -port= is provided, use that. Otherwise use the default port.
    return static_cast<uint16_t>(gArgs.GetIntArg("-port", Params().GetDefaultPort()));
}

// Determine the "best" local address for a particular peer.
[[nodiscard]] static std::optional<CService> GetLocal(const CNode& peer)
{
    if (!fListen) return std::nullopt;

    std::optional<CService> addr;
    int nBestScore = -1;
    int nBestReachability = -1;
    {
        LOCK(g_maplocalhost_mutex);
        for (const auto& [local_addr, local_service_info] : mapLocalHost) {
            // For privacy reasons, don't advertise our privacy-network address
            // to other networks and don't advertise our other-network address
            // to privacy networks.
            if (local_addr.GetNetwork() != peer.ConnectedThroughNetwork()
                && (local_addr.IsPrivacyNet() || peer.IsConnectedThroughPrivacyNet())) {
                continue;
            }
            const int nScore{local_service_info.nScore};
            const int nReachability{local_addr.GetReachabilityFrom(peer.addr)};
            if (nReachability > nBestReachability || (nReachability == nBestReachability && nScore > nBestScore)) {
                addr.emplace(CService{local_addr, local_service_info.nPort});
                nBestReachability = nReachability;
                nBestScore = nScore;
            }
        }
    }
    return addr;
}

//! Convert the serialized seeds into usable address objects.
static std::vector<CAddress> ConvertSeeds(const std::vector<uint8_t> &vSeedsIn)
{
    // It'll only connect to one or two seed nodes because once it connects,
    // it'll get a pile of addresses with newer timestamps.
    // Seed nodes are given a random 'last seen time' of between one and two
    // weeks ago.
    const auto one_week{7 * 24h};
    std::vector<CAddress> vSeedsOut;
    FastRandomContext rng;
    ParamsStream s{DataStream{vSeedsIn}, CAddress::V2_NETWORK};
    while (!s.eof()) {
        CService endpoint;
        s >> endpoint;
        CAddress addr{endpoint, SeedsServiceFlags()};
        addr.nTime = rng.rand_uniform_delay(Now<NodeSeconds>() - one_week, -one_week);
        LogPrint(BCLog::NET, "Added hardcoded seed: %s\n", addr.ToStringAddrPort());
        vSeedsOut.push_back(addr);
    }
    return vSeedsOut;
}

// Determine the "best" local address for a particular peer.
// If none, return the unroutable 0.0.0.0 but filled in with
// the normal parameters, since the IP may be changed to a useful
// one by discovery.
CService GetLocalAddress(const CNode& peer)
{
    return GetLocal(peer).value_or(CService{CNetAddr(), GetListenPort()});
}

static int GetnScore(const CService& addr)
{
    LOCK(g_maplocalhost_mutex);
    const auto it = mapLocalHost.find(addr);
    return (it != mapLocalHost.end()) ? it->second.nScore : 0;
}

// Is our peer's addrLocal potentially useful as an external IP source?
[[nodiscard]] static bool IsPeerAddrLocalGood(CNode *pnode)
{
    CService addrLocal = pnode->GetAddrLocal();
    return fDiscover && pnode->addr.IsRoutable() && addrLocal.IsRoutable() &&
           g_reachable_nets.Contains(addrLocal);
}

std::optional<CService> GetLocalAddrForPeer(CNode& node)
{
    CService addrLocal{GetLocalAddress(node)};
    // If discovery is enabled, sometimes give our peer the address it
    // tells us that it sees us as in case it has a better idea of our
    // address than we do.
    FastRandomContext rng;
    if (IsPeerAddrLocalGood(&node) && (!addrLocal.IsRoutable() ||
         rng.randbits((GetnScore(addrLocal) > LOCAL_MANUAL) ? 3 : 1) == 0))
    {
        if (node.IsInboundConn()) {
            // For inbound connections, assume both the address and the port
            // as seen from the peer.
            addrLocal = CService{node.GetAddrLocal()};
        } else {
            // For outbound connections, assume just the address as seen from
            // the peer and leave the port in `addrLocal` as returned by
            // `GetLocalAddress()` above. The peer has no way to observe our
            // listening port when we have initiated the connection.
            addrLocal.SetIP(node.GetAddrLocal());
        }
    }
    if (addrLocal.IsRoutable()) {
        LogPrint(BCLog::NET, "Advertising address %s to peer=%d\n", addrLocal.ToStringAddrPort(), node.GetId());
        return addrLocal;
    }
    // Address is unroutable. Don't advertise.
    return std::nullopt;
}

// learn a new local address
bool AddLocal(const CService& addr_, int nScore)
{
    CService addr{MaybeFlipIPv6toCJDNS(addr_)};

    if (!addr.IsRoutable())
        return false;

    if (!fDiscover && nScore < LOCAL_MANUAL)
        return false;

    if (!g_reachable_nets.Contains(addr))
        return false;

    LogPrintf("AddLocal(%s,%i)\n", addr.ToStringAddrPort(), nScore);

    {
        LOCK(g_maplocalhost_mutex);
        const auto [it, is_newly_added] = mapLocalHost.emplace(addr, LocalServiceInfo());
        LocalServiceInfo &info = it->second;
        if (is_newly_added || nScore >= info.nScore) {
            info.nScore = nScore + (is_newly_added ? 0 : 1);
            info.nPort = addr.GetPort();
        }
    }

    return true;
}

bool AddLocal(const CNetAddr &addr, int nScore)
{
    return AddLocal(CService(addr, GetListenPort()), nScore);
}

void RemoveLocal(const CService& addr)
{
    LOCK(g_maplocalhost_mutex);
    LogPrintf("RemoveLocal(%s)\n", addr.ToStringAddrPort());
    mapLocalHost.erase(addr);
}

/** vote for a local address */
bool SeenLocal(const CService& addr)
{
    LOCK(g_maplocalhost_mutex);
    const auto it = mapLocalHost.find(addr);
    if (it == mapLocalHost.end()) return false;
    ++it->second.nScore;
    return true;
}


/** check whether a given address is potentially local */
bool IsLocal(const CService& addr)
{
    LOCK(g_maplocalhost_mutex);
    return mapLocalHost.count(addr) > 0;
}

CNode* CConnman::FindNode(const CNetAddr& ip)
{
    LOCK(m_nodes_mutex);
    for (CNode* pnode : m_nodes) {
      if (static_cast<CNetAddr>(pnode->addr) == ip) {
            return pnode;
        }
    }
    return nullptr;
}

CNode* CConnman::FindNode(const std::string& addrName)
{
    LOCK(m_nodes_mutex);
    for (CNode* pnode : m_nodes) {
        if (pnode->m_addr_name == addrName) {
            return pnode;
        }
    }
    return nullptr;
}

CNode* CConnman::FindNode(const CService& addr)
{
    LOCK(m_nodes_mutex);
    for (CNode* pnode : m_nodes) {
        if (static_cast<CService>(pnode->addr) == addr) {
            return pnode;
        }
    }
    return nullptr;
}

bool CConnman::AlreadyConnectedToAddress(const CAddress& addr)
{
    return FindNode(static_cast<CNetAddr>(addr)) || FindNode(addr.ToStringAddrPort());
}

bool CConnman::CheckIncomingNonce(uint64_t nonce)
{
    LOCK(m_nodes_mutex);
    for (const CNode* pnode : m_nodes) {
        if (!pnode->fSuccessfullyConnected && !pnode->IsInboundConn() && pnode->GetLocalNonce() == nonce)
            return false;
    }
    return true;
}

/** Get the bind address for a socket as CAddress */
static CAddress GetBindAddress(const Sock& sock)
{
    CAddress addr_bind;
    struct sockaddr_storage sockaddr_bind;
    socklen_t sockaddr_bind_len = sizeof(sockaddr_bind);
    if (!sock.GetSockName((struct sockaddr*)&sockaddr_bind, &sockaddr_bind_len)) {
        addr_bind.SetSockAddr((const struct sockaddr*)&sockaddr_bind);
    } else {
        LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "getsockname failed\n");
    }
    return addr_bind;
}

CNode* CConnman::ConnectNode(CAddress addrConnect, const char *pszDest, bool fCountFailure, ConnectionType conn_type, bool use_v2transport)
{
    AssertLockNotHeld(m_unused_i2p_sessions_mutex);
    assert(conn_type != ConnectionType::INBOUND);

    if (pszDest == nullptr) {
        if (IsLocal(addrConnect))
            return nullptr;

        // Look for an existing connection
        CNode* pnode = FindNode(static_cast<CService>(addrConnect));
        if (pnode)
        {
            LogPrintf("Failed to open new connection, already connected\n");
            return nullptr;
        }
    }

    LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "trying %s connection %s lastseen=%.1fhrs\n",
        use_v2transport ? "v2" : "v1",
        pszDest ? pszDest : addrConnect.ToStringAddrPort(),
        Ticks<HoursDouble>(pszDest ? 0h : Now<NodeSeconds>() - addrConnect.nTime));

    // Resolve
    const uint16_t default_port{pszDest != nullptr ? GetDefaultPort(pszDest) :
                                                     m_params.GetDefaultPort()};

    // Collection of addresses to try to connect to: either all dns resolved addresses if a domain name (pszDest) is provided, or addrConnect otherwise.
    std::vector<CAddress> connect_to{};
    if (pszDest) {
        std::vector<CService> resolved{Lookup(pszDest, default_port, fNameLookup && !HaveNameProxy(), 256)};
        if (!resolved.empty()) {
            std::shuffle(resolved.begin(), resolved.end(), FastRandomContext());
            // If the connection is made by name, it can be the case that the name resolves to more than one address.
            // We don't want to connect any more of them if we are already connected to one
            for (const auto& r : resolved) {
                addrConnect = CAddress{MaybeFlipIPv6toCJDNS(r), NODE_NONE};
                if (!addrConnect.IsValid()) {
                    LogPrint(BCLog::NET, "Resolver returned invalid address %s for %s\n", addrConnect.ToStringAddrPort(), pszDest);
                    return nullptr;
                }
                // It is possible that we already have a connection to the IP/port pszDest resolved to.
                // In that case, drop the connection that was just created.
                LOCK(m_nodes_mutex);
                CNode* pnode = FindNode(static_cast<CService>(addrConnect));
                if (pnode) {
                    LogPrintf("Not opening a connection to %s, already connected to %s\n", pszDest, addrConnect.ToStringAddrPort());
                    return nullptr;
                }
                // Add the address to the resolved addresses vector so we can try to connect to it later on
                connect_to.push_back(addrConnect);
            }
        } else {
            // For resolution via proxy
            connect_to.push_back(addrConnect);
        }
    } else {
        // Connect via addrConnect directly
        connect_to.push_back(addrConnect);
    }

    // Connect
    std::unique_ptr<Sock> sock;
    Proxy proxy;
    CAddress addr_bind;
    assert(!addr_bind.IsValid());
    std::unique_ptr<i2p::sam::Session> i2p_transient_session;

    for (auto& target_addr: connect_to) {
        if (target_addr.IsValid()) {
            const bool use_proxy{GetProxy(target_addr.GetNetwork(), proxy)};
            bool proxyConnectionFailed = false;

            if (target_addr.IsI2P() && use_proxy) {
                i2p::Connection conn;
                bool connected{false};

                if (m_i2p_sam_session) {
                    connected = m_i2p_sam_session->Connect(target_addr, conn, proxyConnectionFailed);
                } else {
                    {
                        LOCK(m_unused_i2p_sessions_mutex);
                        if (m_unused_i2p_sessions.empty()) {
                            i2p_transient_session =
                                std::make_unique<i2p::sam::Session>(proxy, &interruptNet);
                        } else {
                            i2p_transient_session.swap(m_unused_i2p_sessions.front());
                            m_unused_i2p_sessions.pop();
                        }
                    }
                    connected = i2p_transient_session->Connect(target_addr, conn, proxyConnectionFailed);
                    if (!connected) {
                        LOCK(m_unused_i2p_sessions_mutex);
                        if (m_unused_i2p_sessions.size() < MAX_UNUSED_I2P_SESSIONS_SIZE) {
                            m_unused_i2p_sessions.emplace(i2p_transient_session.release());
                        }
                    }
                }

                if (connected) {
                    sock = std::move(conn.sock);
                    addr_bind = CAddress{conn.me, NODE_NONE};
                }
            } else if (use_proxy) {
                LogPrintLevel(BCLog::PROXY, BCLog::Level::Debug, "Using proxy: %s to connect to %s\n", proxy.ToString(), target_addr.ToStringAddrPort());
                sock = ConnectThroughProxy(proxy, target_addr.ToStringAddr(), target_addr.GetPort(), proxyConnectionFailed);
            } else {
                // no proxy needed (none set for target network)
                sock = ConnectDirectly(target_addr, conn_type == ConnectionType::MANUAL);
            }
            if (!proxyConnectionFailed) {
                // If a connection to the node was attempted, and failure (if any) is not caused by a problem connecting to
                // the proxy, mark this as an attempt.
                addrman.Attempt(target_addr, fCountFailure);
            }
        } else if (pszDest && GetNameProxy(proxy)) {
            std::string host;
            uint16_t port{default_port};
            SplitHostPort(std::string(pszDest), port, host);
            bool proxyConnectionFailed;
            sock = ConnectThroughProxy(proxy, host, port, proxyConnectionFailed);
        }
        // Check any other resolved address (if any) if we fail to connect
        if (!sock) {
            continue;
        }

        NetPermissionFlags permission_flags = NetPermissionFlags::None;
        std::vector<NetWhitelistPermissions> whitelist_permissions = conn_type == ConnectionType::MANUAL ? vWhitelistedRangeOutgoing : std::vector<NetWhitelistPermissions>{};
        AddWhitelistPermissionFlags(permission_flags, target_addr, whitelist_permissions);

        // Add node
        NodeId id = GetNewNodeId();
        uint64_t nonce = GetDeterministicRandomizer(RANDOMIZER_ID_LOCALHOSTNONCE).Write(id).Finalize();
        if (!addr_bind.IsValid()) {
            addr_bind = GetBindAddress(*sock);
        }
        CNode* pnode = new CNode(id,
                                std::move(sock),
                                target_addr,
                                CalculateKeyedNetGroup(target_addr),
                                nonce,
                                addr_bind,
                                pszDest ? pszDest : "",
                                conn_type,
                                /*inbound_onion=*/false,
                                CNodeOptions{
                                    .permission_flags = permission_flags,
                                    .i2p_sam_session = std::move(i2p_transient_session),
                                    .recv_flood_size = nReceiveFloodSize,
                                    .use_v2transport = use_v2transport,
                                });
        pnode->AddRef();

        // We're making a new connection, harvest entropy from the time (and our peer count)
        RandAddEvent((uint32_t)id);

        return pnode;
    }

    return nullptr;
}

void CNode::CloseSocketDisconnect()
{
    fDisconnect = true;
    LOCK(m_sock_mutex);
    if (m_sock) {
        LogPrint(BCLog::NET, "disconnecting peer=%d\n", id);
        m_sock.reset();
    }
    m_i2p_sam_session.reset();
}

void CConnman::AddWhitelistPermissionFlags(NetPermissionFlags& flags, const CNetAddr &addr, const std::vector<NetWhitelistPermissions>& ranges) const {
    for (const auto& subnet : ranges) {
        if (subnet.m_subnet.Match(addr)) {
            NetPermissions::AddFlag(flags, subnet.m_flags);
        }
    }
    if (NetPermissions::HasFlag(flags, NetPermissionFlags::Implicit)) {
        NetPermissions::ClearFlag(flags, NetPermissionFlags::Implicit);
        if (whitelist_forcerelay) NetPermissions::AddFlag(flags, NetPermissionFlags::ForceRelay);
        if (whitelist_relay) NetPermissions::AddFlag(flags, NetPermissionFlags::Relay);
        NetPermissions::AddFlag(flags, NetPermissionFlags::Mempool);
        NetPermissions::AddFlag(flags, NetPermissionFlags::NoBan);
    }
}

CService CNode::GetAddrLocal() const
{
    AssertLockNotHeld(m_addr_local_mutex);
    LOCK(m_addr_local_mutex);
    return m_addr_local;
}

void CNode::SetAddrLocal(const CService& addrLocalIn) {
    AssertLockNotHeld(m_addr_local_mutex);
    LOCK(m_addr_local_mutex);
    if (Assume(!m_addr_local.IsValid())) { // Addr local can only be set once during version msg processing
        m_addr_local = addrLocalIn;
    }
}

Network CNode::ConnectedThroughNetwork() const
{
    return m_inbound_onion ? NET_ONION : addr.GetNetClass();
}

bool CNode::IsConnectedThroughPrivacyNet() const
{
    return m_inbound_onion || addr.IsPrivacyNet();
}

#undef X
#define X(name) stats.name = name
void CNode::CopyStats(CNodeStats& stats)
{
    stats.nodeid = this->GetId();
    X(addr);
    X(addrBind);
    stats.m_network = ConnectedThroughNetwork();
    X(m_last_send);
    X(m_last_recv);
    X(m_last_tx_time);
    X(m_last_block_time);
    X(m_connected);
    X(m_addr_name);
    X(nVersion);
    {
        LOCK(m_subver_mutex);
        X(cleanSubVer);
    }
    stats.fInbound = IsInboundConn();
    X(m_bip152_highbandwidth_to);
    X(m_bip152_highbandwidth_from);
    {
        LOCK(cs_vSend);
        X(mapSendBytesPerMsgType);
        X(nSendBytes);
    }
    {
        LOCK(cs_vRecv);
        X(mapRecvBytesPerMsgType);
        X(nRecvBytes);
        Transport::Info info = m_transport->GetInfo();
        stats.m_transport_type = info.transport_type;
        if (info.session_id) stats.m_session_id = HexStr(*info.session_id);
    }
    X(m_permission_flags);

    X(m_last_ping_time);
    X(m_min_ping_time);

    // Leave string empty if addrLocal invalid (not filled in yet)
    CService addrLocalUnlocked = GetAddrLocal();
    stats.addrLocal = addrLocalUnlocked.IsValid() ? addrLocalUnlocked.ToStringAddrPort() : "";

    X(m_conn_type);
}
#undef X

bool CNode::ReceiveMsgBytes(Span<const uint8_t> msg_bytes, bool& complete)
{
    complete = false;
    const auto time = GetTime<std::chrono::microseconds>();
    LOCK(cs_vRecv);
    m_last_recv = std::chrono::duration_cast<std::chrono::seconds>(time);
    nRecvBytes += msg_bytes.size();
    while (msg_bytes.size() > 0) {
        // absorb network data
        if (!m_transport->ReceivedBytes(msg_bytes)) {
            // Serious transport problem, disconnect from the peer.
            return false;
        }

        if (m_transport->ReceivedMessageComplete()) {
            // decompose a transport agnostic CNetMessage from the deserializer
            bool reject_message{false};
            CNetMessage msg = m_transport->GetReceivedMessage(time, reject_message);
            if (reject_message) {
                // Message deserialization failed. Drop the message but don't disconnect the peer.
                // store the size of the corrupt message
                mapRecvBytesPerMsgType.at(NET_MESSAGE_TYPE_OTHER) += msg.m_raw_message_size;
                continue;
            }

            // Store received bytes per message type.
            // To prevent a memory DOS, only allow known message types.
            auto i = mapRecvBytesPerMsgType.find(msg.m_type);
            if (i == mapRecvBytesPerMsgType.end()) {
                i = mapRecvBytesPerMsgType.find(NET_MESSAGE_TYPE_OTHER);
            }
            assert(i != mapRecvBytesPerMsgType.end());
            i->second += msg.m_raw_message_size;

            // push the message to the process queue,
            vRecvMsg.push_back(std::move(msg));

            complete = true;
        }
    }

    return true;
}

V1Transport::V1Transport(const NodeId node_id) noexcept
    : m_magic_bytes{Params().MessageStart()}, m_node_id{node_id}
{
    LOCK(m_recv_mutex);
    Reset();
}

Transport::Info V1Transport::GetInfo() const noexcept
{
    return {.transport_type = TransportProtocolType::V1, .session_id = {}};
}

int V1Transport::readHeader(Span<const uint8_t> msg_bytes)
{
    AssertLockHeld(m_recv_mutex);
    // copy data to temporary parsing buffer
    unsigned int nRemaining = CMessageHeader::HEADER_SIZE - nHdrPos;
    unsigned int nCopy = std::min<unsigned int>(nRemaining, msg_bytes.size());

    memcpy(&hdrbuf[nHdrPos], msg_bytes.data(), nCopy);
    nHdrPos += nCopy;

    // if header incomplete, exit
    if (nHdrPos < CMessageHeader::HEADER_SIZE)
        return nCopy;

    // deserialize to CMessageHeader
    try {
        hdrbuf >> hdr;
    }
    catch (const std::exception&) {
        LogPrint(BCLog::NET, "Header error: Unable to deserialize, peer=%d\n", m_node_id);
        return -1;
    }

    // Check start string, network magic
    if (hdr.pchMessageStart != m_magic_bytes) {
        LogPrint(BCLog::NET, "Header error: Wrong MessageStart %s received, peer=%d\n", HexStr(hdr.pchMessageStart), m_node_id);
        return -1;
    }

    // reject messages larger than MAX_SIZE or MAX_PROTOCOL_MESSAGE_LENGTH
    if (hdr.nMessageSize > MAX_SIZE || hdr.nMessageSize > MAX_PROTOCOL_MESSAGE_LENGTH) {
        LogPrint(BCLog::NET, "Header error: Size too large (%s, %u bytes), peer=%d\n", SanitizeString(hdr.GetCommand()), hdr.nMessageSize, m_node_id);
        return -1;
    }

    // switch state to reading message data
    in_data = true;

    return nCopy;
}

int V1Transport::readData(Span<const uint8_t> msg_bytes)
{
    AssertLockHeld(m_recv_mutex);
    unsigned int nRemaining = hdr.nMessageSize - nDataPos;
    unsigned int nCopy = std::min<unsigned int>(nRemaining, msg_bytes.size());

    if (vRecv.size() < nDataPos + nCopy) {
        // Allocate up to 256 KiB ahead, but never more than the total message size.
        vRecv.resize(std::min(hdr.nMessageSize, nDataPos + nCopy + 256 * 1024));
    }

    hasher.Write(msg_bytes.first(nCopy));
    memcpy(&vRecv[nDataPos], msg_bytes.data(), nCopy);
    nDataPos += nCopy;

    return nCopy;
}

const uint256& V1Transport::GetMessageHash() const
{
    AssertLockHeld(m_recv_mutex);
    assert(CompleteInternal());
    if (data_hash.IsNull())
        hasher.Finalize(data_hash);
    return data_hash;
}

CNetMessage V1Transport::GetReceivedMessage(const std::chrono::microseconds time, bool& reject_message)
{
    AssertLockNotHeld(m_recv_mutex);
    // Initialize out parameter
    reject_message = false;
    // decompose a single CNetMessage from the TransportDeserializer
    LOCK(m_recv_mutex);
    CNetMessage msg(std::move(vRecv));

    // store message type string, time, and sizes
    msg.m_type = hdr.GetCommand();
    msg.m_time = time;
    msg.m_message_size = hdr.nMessageSize;
    msg.m_raw_message_size = hdr.nMessageSize + CMessageHeader::HEADER_SIZE;

    uint256 hash = GetMessageHash();

    // We just received a message off the wire, harvest entropy from the time (and the message checksum)
    RandAddEvent(ReadLE32(hash.begin()));

    // Check checksum and header message type string
    if (memcmp(hash.begin(), hdr.pchChecksum, CMessageHeader::CHECKSUM_SIZE) != 0) {
        LogPrint(BCLog::NET, "Header error: Wrong checksum (%s, %u bytes), expected %s was %s, peer=%d\n",
                 SanitizeString(msg.m_type), msg.m_message_size,
                 HexStr(Span{hash}.first(CMessageHeader::CHECKSUM_SIZE)),
                 HexStr(hdr.pchChecksum),
                 m_node_id);
        reject_message = true;
    } else if (!hdr.IsCommandValid()) {
        LogPrint(BCLog::NET, "Header error: Invalid message type (%s, %u bytes), peer=%d\n",
                 SanitizeString(hdr.GetCommand()), msg.m_message_size, m_node_id);
        reject_message = true;
    }

    // Always reset the network deserializer (prepare for the next message)
    Reset();
    return msg;
}

bool V1Transport::SetMessageToSend(CSerializedNetMsg& msg) noexcept
{
    AssertLockNotHeld(m_send_mutex);
    // Determine whether a new message can be set.
    LOCK(m_send_mutex);
    if (m_sending_header || m_bytes_sent < m_message_to_send.data.size()) return false;

    // create dbl-sha256 checksum
    uint256 hash = Hash(msg.data);

    // create header
    CMessageHeader hdr(m_magic_bytes, msg.m_type.c_str(), msg.data.size());
    memcpy(hdr.pchChecksum, hash.begin(), CMessageHeader::CHECKSUM_SIZE);

    // serialize header
    m_header_to_send.clear();
    VectorWriter{m_header_to_send, 0, hdr};

    // update state
    m_message_to_send = std::move(msg);
    m_sending_header = true;
    m_bytes_sent = 0;
    return true;
}

Transport::BytesToSend V1Transport::GetBytesToSend(bool have_next_message) const noexcept
{
    AssertLockNotHeld(m_send_mutex);
    LOCK(m_send_mutex);
    if (m_sending_header) {
        return {Span{m_header_to_send}.subspan(m_bytes_sent),
                // We have more to send after the header if the message has payload, or if there
                // is a next message after that.
                have_next_message || !m_message_to_send.data.empty(),
                m_message_to_send.m_type
               };
    } else {
        return {Span{m_message_to_send.data}.subspan(m_bytes_sent),
                // We only have more to send after this message's payload if there is another
                // message.
                have_next_message,
                m_message_to_send.m_type
               };
    }
}

void V1Transport::MarkBytesSent(size_t bytes_sent) noexcept
{
    AssertLockNotHeld(m_send_mutex);
    LOCK(m_send_mutex);
    m_bytes_sent += bytes_sent;
    if (m_sending_header && m_bytes_sent == m_header_to_send.size()) {
        // We're done sending a message's header. Switch to sending its data bytes.
        m_sending_header = false;
        m_bytes_sent = 0;
    } else if (!m_sending_header && m_bytes_sent == m_message_to_send.data.size()) {
        // We're done sending a message's data. Wipe the data vector to reduce memory consumption.
        ClearShrink(m_message_to_send.data);
        m_bytes_sent = 0;
    }
}

size_t V1Transport::GetSendMemoryUsage() const noexcept
{
    AssertLockNotHeld(m_send_mutex);
    LOCK(m_send_mutex);
    // Don't count sending-side fields besides m_message_to_send, as they're all small and bounded.
    return m_message_to_send.GetMemoryUsage();
}

namespace {

/** List of short messages as defined in BIP324, in order.
 *
 * Only message types that are actually implemented in this codebase need to be listed, as other
 * messages get ignored anyway - whether we know how to decode them or not.
 */
const std::array<std::string, 33> V2_MESSAGE_IDS = {
    "", // 12 bytes follow encoding the message type like in V1
    NetMsgType::ADDR,
    NetMsgType::BLOCK,
    NetMsgType::BLOCKTXN,
    NetMsgType::CMPCTBLOCK,
    NetMsgType::FEEFILTER,
    NetMsgType::FILTERADD,
    NetMsgType::FILTERCLEAR,
    NetMsgType::FILTERLOAD,
    NetMsgType::GETBLOCKS,
    NetMsgType::GETBLOCKTXN,
    NetMsgType::GETDATA,
    NetMsgType::GETHEADERS,
    NetMsgType::HEADERS,
    NetMsgType::INV,
    NetMsgType::MEMPOOL,
    NetMsgType::MERKLEBLOCK,
    NetMsgType::NOTFOUND,
    NetMsgType::PING,
    NetMsgType::PONG,
    NetMsgType::SENDCMPCT,
    NetMsgType::TX,
    NetMsgType::GETCFILTERS,
    NetMsgType::CFILTER,
    NetMsgType::GETCFHEADERS,
    NetMsgType::CFHEADERS,
    NetMsgType::GETCFCHECKPT,
    NetMsgType::CFCHECKPT,
    NetMsgType::ADDRV2,
    // Unimplemented message types that are assigned in BIP324:
    "",
    "",
    "",
    ""
};

class V2MessageMap
{
    std::unordered_map<std::string, uint8_t> m_map;

public:
    V2MessageMap() noexcept
    {
        for (size_t i = 1; i < std::size(V2_MESSAGE_IDS); ++i) {
            m_map.emplace(V2_MESSAGE_IDS[i], i);
        }
    }

    std::optional<uint8_t> operator()(const std::string& message_name) const noexcept
    {
        auto it = m_map.find(message_name);
        if (it == m_map.end()) return std::nullopt;
        return it->second;
    }
};

const V2MessageMap V2_MESSAGE_MAP;

std::vector<uint8_t> GenerateRandomGarbage() noexcept
{
    std::vector<uint8_t> ret;
    FastRandomContext rng;
    ret.resize(rng.randrange(V2Transport::MAX_GARBAGE_LEN + 1));
    rng.fillrand(MakeWritableByteSpan(ret));
    return ret;
}

} // namespace

void V2Transport::StartSendingHandshake() noexcept
{
    AssertLockHeld(m_send_mutex);
    Assume(m_send_state == SendState::AWAITING_KEY);
    Assume(m_send_buffer.empty());
    // Initialize the send buffer with ellswift pubkey + provided garbage.
    m_send_buffer.resize(EllSwiftPubKey::size() + m_send_garbage.size());
    std::copy(std::begin(m_cipher.GetOurPubKey()), std::end(m_cipher.GetOurPubKey()), MakeWritableByteSpan(m_send_buffer).begin());
    std::copy(m_send_garbage.begin(), m_send_garbage.end(), m_send_buffer.begin() + EllSwiftPubKey::size());
    // We cannot wipe m_send_garbage as it will still be used as AAD later in the handshake.
}

V2Transport::V2Transport(NodeId nodeid, bool initiating, const CKey& key, Span<const std::byte> ent32, std::vector<uint8_t> garbage) noexcept
    : m_cipher{key, ent32}, m_initiating{initiating}, m_nodeid{nodeid},
      m_v1_fallback{nodeid},
      m_recv_state{initiating ? RecvState::KEY : RecvState::KEY_MAYBE_V1},
      m_send_garbage{std::move(garbage)},
      m_send_state{initiating ? SendState::AWAITING_KEY : SendState::MAYBE_V1}
{
    Assume(m_send_garbage.size() <= MAX_GARBAGE_LEN);
    // Start sending immediately if we're the initiator of the connection.
    if (initiating) {
        LOCK(m_send_mutex);
        StartSendingHandshake();
    }
}

V2Transport::V2Transport(NodeId nodeid, bool initiating) noexcept
    : V2Transport{nodeid, initiating, GenerateRandomKey(),
                  MakeByteSpan(GetRandHash()), GenerateRandomGarbage()} {}

void V2Transport::SetReceiveState(RecvState recv_state) noexcept
{
    AssertLockHeld(m_recv_mutex);
    // Enforce allowed state transitions.
    switch (m_recv_state) {
    case RecvState::KEY_MAYBE_V1:
        Assume(recv_state == RecvState::KEY || recv_state == RecvState::V1);
        break;
    case RecvState::KEY:
        Assume(recv_state == RecvState::GARB_GARBTERM);
        break;
    case RecvState::GARB_GARBTERM:
        Assume(recv_state == RecvState::VERSION);
        break;
    case RecvState::VERSION:
        Assume(recv_state == RecvState::APP);
        break;
    case RecvState::APP:
        Assume(recv_state == RecvState::APP_READY);
        break;
    case RecvState::APP_READY:
        Assume(recv_state == RecvState::APP);
        break;
    case RecvState::V1:
        Assume(false); // V1 state cannot be left
        break;
    }
    // Change state.
    m_recv_state = recv_state;
}

void V2Transport::SetSendState(SendState send_state) noexcept
{
    AssertLockHeld(m_send_mutex);
    // Enforce allowed state transitions.
    switch (m_send_state) {
    case SendState::MAYBE_V1:
        Assume(send_state == SendState::V1 || send_state == SendState::AWAITING_KEY);
        break;
    case SendState::AWAITING_KEY:
        Assume(send_state == SendState::READY);
        break;
    case SendState::READY:
    case SendState::V1:
        Assume(false); // Final states
        break;
    }
    // Change state.
    m_send_state = send_state;
}

bool V2Transport::ReceivedMessageComplete() const noexcept
{
    AssertLockNotHeld(m_recv_mutex);
    LOCK(m_recv_mutex);
    if (m_recv_state == RecvState::V1) return m_v1_fallback.ReceivedMessageComplete();

    return m_recv_state == RecvState::APP_READY;
}

void V2Transport::ProcessReceivedMaybeV1Bytes() noexcept
{
    AssertLockHeld(m_recv_mutex);
    AssertLockNotHeld(m_send_mutex);
    Assume(m_recv_state == RecvState::KEY_MAYBE_V1);
    // We still have to determine if this is a v1 or v2 connection. The bytes being received could
    // be the beginning of either a v1 packet (network magic + "version\x00\x00\x00\x00\x00"), or
    // of a v2 public key. BIP324 specifies that a mismatch with this 16-byte string should trigger
    // sending of the key.
    std::array<uint8_t, V1_PREFIX_LEN> v1_prefix = {0, 0, 0, 0, 'v', 'e', 'r', 's', 'i', 'o', 'n', 0, 0, 0, 0, 0};
    std::copy(std::begin(Params().MessageStart()), std::end(Params().MessageStart()), v1_prefix.begin());
    Assume(m_recv_buffer.size() <= v1_prefix.size());
    if (!std::equal(m_recv_buffer.begin(), m_recv_buffer.end(), v1_prefix.begin())) {
        // Mismatch with v1 prefix, so we can assume a v2 connection.
        SetReceiveState(RecvState::KEY); // Convert to KEY state, leaving received bytes around.
        // Transition the sender to AWAITING_KEY state and start sending.
        LOCK(m_send_mutex);
        SetSendState(SendState::AWAITING_KEY);
        StartSendingHandshake();
    } else if (m_recv_buffer.size() == v1_prefix.size()) {
        // Full match with the v1 prefix, so fall back to v1 behavior.
        LOCK(m_send_mutex);
        Span<const uint8_t> feedback{m_recv_buffer};
        // Feed already received bytes to v1 transport. It should always accept these, because it's
        // less than the size of a v1 header, and these are the first bytes fed to m_v1_fallback.
        bool ret = m_v1_fallback.ReceivedBytes(feedback);
        Assume(feedback.empty());
        Assume(ret);
        SetReceiveState(RecvState::V1);
        SetSendState(SendState::V1);
        // Reset v2 transport buffers to save memory.
        ClearShrink(m_recv_buffer);
        ClearShrink(m_send_buffer);
    } else {
        // We have not received enough to distinguish v1 from v2 yet. Wait until more bytes come.
    }
}

bool V2Transport::ProcessReceivedKeyBytes() noexcept
{
    AssertLockHeld(m_recv_mutex);
    AssertLockNotHeld(m_send_mutex);
    Assume(m_recv_state == RecvState::KEY);
    Assume(m_recv_buffer.size() <= EllSwiftPubKey::size());

    // As a special exception, if bytes 4-16 of the key on a responder connection match the
    // corresponding bytes of a V1 version message, but bytes 0-4 don't match the network magic
    // (if they did, we'd have switched to V1 state already), assume this is a peer from
    // another network, and disconnect them. They will almost certainly disconnect us too when
    // they receive our uniformly random key and garbage, but detecting this case specially
    // means we can log it.
    static constexpr std::array<uint8_t, 12> MATCH = {'v', 'e', 'r', 's', 'i', 'o', 'n', 0, 0, 0, 0, 0};
    static constexpr size_t OFFSET = std::tuple_size_v<MessageStartChars>;
    if (!m_initiating && m_recv_buffer.size() >= OFFSET + MATCH.size()) {
        if (std::equal(MATCH.begin(), MATCH.end(), m_recv_buffer.begin() + OFFSET)) {
            LogPrint(BCLog::NET, "V2 transport error: V1 peer with wrong MessageStart %s\n",
                     HexStr(Span(m_recv_buffer).first(OFFSET)));
            return false;
        }
    }

    if (m_recv_buffer.size() == EllSwiftPubKey::size()) {
        // Other side's key has been fully received, and can now be Diffie-Hellman combined with
        // our key to initialize the encryption ciphers.

        // Initialize the ciphers.
        EllSwiftPubKey ellswift(MakeByteSpan(m_recv_buffer));
        LOCK(m_send_mutex);
        m_cipher.Initialize(ellswift, m_initiating);

        // Switch receiver state to GARB_GARBTERM.
        SetReceiveState(RecvState::GARB_GARBTERM);
        m_recv_buffer.clear();

        // Switch sender state to READY.
        SetSendState(SendState::READY);

        // Append the garbage terminator to the send buffer.
        m_send_buffer.resize(m_send_buffer.size() + BIP324Cipher::GARBAGE_TERMINATOR_LEN);
        std::copy(m_cipher.GetSendGarbageTerminator().begin(),
                  m_cipher.GetSendGarbageTerminator().end(),
                  MakeWritableByteSpan(m_send_buffer).last(BIP324Cipher::GARBAGE_TERMINATOR_LEN).begin());

        // Construct version packet in the send buffer, with the sent garbage data as AAD.
        m_send_buffer.resize(m_send_buffer.size() + BIP324Cipher::EXPANSION + VERSION_CONTENTS.size());
        m_cipher.Encrypt(
            /*contents=*/VERSION_CONTENTS,
            /*aad=*/MakeByteSpan(m_send_garbage),
            /*ignore=*/false,
            /*output=*/MakeWritableByteSpan(m_send_buffer).last(BIP324Cipher::EXPANSION + VERSION_CONTENTS.size()));
        // We no longer need the garbage.
        ClearShrink(m_send_garbage);
    } else {
        // We still have to receive more key bytes.
    }
    return true;
}

bool V2Transport::ProcessReceivedGarbageBytes() noexcept
{
    AssertLockHeld(m_recv_mutex);
    Assume(m_recv_state == RecvState::GARB_GARBTERM);
    Assume(m_recv_buffer.size() <= MAX_GARBAGE_LEN + BIP324Cipher::GARBAGE_TERMINATOR_LEN);
    if (m_recv_buffer.size() >= BIP324Cipher::GARBAGE_TERMINATOR_LEN) {
        if (MakeByteSpan(m_recv_buffer).last(BIP324Cipher::GARBAGE_TERMINATOR_LEN) == m_cipher.GetReceiveGarbageTerminator()) {
            // Garbage terminator received. Store garbage to authenticate it as AAD later.
            m_recv_aad = std::move(m_recv_buffer);
            m_recv_aad.resize(m_recv_aad.size() - BIP324Cipher::GARBAGE_TERMINATOR_LEN);
            m_recv_buffer.clear();
            SetReceiveState(RecvState::VERSION);
        } else if (m_recv_buffer.size() == MAX_GARBAGE_LEN + BIP324Cipher::GARBAGE_TERMINATOR_LEN) {
            // We've reached the maximum length for garbage + garbage terminator, and the
            // terminator still does not match. Abort.
            LogPrint(BCLog::NET, "V2 transport error: missing garbage terminator, peer=%d\n", m_nodeid);
            return false;
        } else {
            // We still need to receive more garbage and/or garbage terminator bytes.
        }
    } else {
        // We have less than GARBAGE_TERMINATOR_LEN (16) bytes, so we certainly need to receive
        // more first.
    }
    return true;
}

bool V2Transport::ProcessReceivedPacketBytes() noexcept
{
    AssertLockHeld(m_recv_mutex);
    Assume(m_recv_state == RecvState::VERSION || m_recv_state == RecvState::APP);

    // The maximum permitted contents length for a packet, consisting of:
    // - 0x00 byte: indicating long message type encoding
    // - 12 bytes of message type
    // - payload
    static constexpr size_t MAX_CONTENTS_LEN =
        1 + CMessageHeader::COMMAND_SIZE +
        std::min<size_t>(MAX_SIZE, MAX_PROTOCOL_MESSAGE_LENGTH);

    if (m_recv_buffer.size() == BIP324Cipher::LENGTH_LEN) {
        // Length descriptor received.
        m_recv_len = m_cipher.DecryptLength(MakeByteSpan(m_recv_buffer));
        if (m_recv_len > MAX_CONTENTS_LEN) {
            LogPrint(BCLog::NET, "V2 transport error: packet too large (%u bytes), peer=%d\n", m_recv_len, m_nodeid);
            return false;
        }
    } else if (m_recv_buffer.size() > BIP324Cipher::LENGTH_LEN && m_recv_buffer.size() == m_recv_len + BIP324Cipher::EXPANSION) {
        // Ciphertext received, decrypt it into m_recv_decode_buffer.
        // Note that it is impossible to reach this branch without hitting the branch above first,
        // as GetMaxBytesToProcess only allows up to LENGTH_LEN into the buffer before that point.
        m_recv_decode_buffer.resize(m_recv_len);
        bool ignore{false};
        bool ret = m_cipher.Decrypt(
            /*input=*/MakeByteSpan(m_recv_buffer).subspan(BIP324Cipher::LENGTH_LEN),
            /*aad=*/MakeByteSpan(m_recv_aad),
            /*ignore=*/ignore,
            /*contents=*/MakeWritableByteSpan(m_recv_decode_buffer));
        if (!ret) {
            LogPrint(BCLog::NET, "V2 transport error: packet decryption failure (%u bytes), peer=%d\n", m_recv_len, m_nodeid);
            return false;
        }
        // We have decrypted a valid packet with the AAD we expected, so clear the expected AAD.
        ClearShrink(m_recv_aad);
        // Feed the last 4 bytes of the Poly1305 authentication tag (and its timing) into our RNG.
        RandAddEvent(ReadLE32(m_recv_buffer.data() + m_recv_buffer.size() - 4));

        // At this point we have a valid packet decrypted into m_recv_decode_buffer. If it's not a
        // decoy, which we simply ignore, use the current state to decide what to do with it.
        if (!ignore) {
            switch (m_recv_state) {
            case RecvState::VERSION:
                // Version message received; transition to application phase. The contents is
                // ignored, but can be used for future extensions.
                SetReceiveState(RecvState::APP);
                break;
            case RecvState::APP:
                // Application message decrypted correctly. It can be extracted using GetMessage().
                SetReceiveState(RecvState::APP_READY);
                break;
            default:
                // Any other state is invalid (this function should not have been called).
                Assume(false);
            }
        }
        // Wipe the receive buffer where the next packet will be received into.
        ClearShrink(m_recv_buffer);
        // In all but APP_READY state, we can wipe the decoded contents.
        if (m_recv_state != RecvState::APP_READY) ClearShrink(m_recv_decode_buffer);
    } else {
        // We either have less than 3 bytes, so we don't know the packet's length yet, or more
        // than 3 bytes but less than the packet's full ciphertext. Wait until those arrive.
    }
    return true;
}

size_t V2Transport::GetMaxBytesToProcess() noexcept
{
    AssertLockHeld(m_recv_mutex);
    switch (m_recv_state) {
    case RecvState::KEY_MAYBE_V1:
        // During the KEY_MAYBE_V1 state we do not allow more than the length of v1 prefix into the
        // receive buffer.
        Assume(m_recv_buffer.size() <= V1_PREFIX_LEN);
        // As long as we're not sure if this is a v1 or v2 connection, don't receive more than what
        // is strictly necessary to distinguish the two (16 bytes). If we permitted more than
        // the v1 header size (24 bytes), we may not be able to feed the already-received bytes
        // back into the m_v1_fallback V1 transport.
        return V1_PREFIX_LEN - m_recv_buffer.size();
    case RecvState::KEY:
        // During the KEY state, we only allow the 64-byte key into the receive buffer.
        Assume(m_recv_buffer.size() <= EllSwiftPubKey::size());
        // As long as we have not received the other side's public key, don't receive more than
        // that (64 bytes), as garbage follows, and locating the garbage terminator requires the
        // key exchange first.
        return EllSwiftPubKey::size() - m_recv_buffer.size();
    case RecvState::GARB_GARBTERM:
        // Process garbage bytes one by one (because terminator may appear anywhere).
        return 1;
    case RecvState::VERSION:
    case RecvState::APP:
        // These three states all involve decoding a packet. Process the length descriptor first,
        // so that we know where the current packet ends (and we don't process bytes from the next
        // packet or decoy yet). Then, process the ciphertext bytes of the current packet.
        if (m_recv_buffer.size() < BIP324Cipher::LENGTH_LEN) {
            return BIP324Cipher::LENGTH_LEN - m_recv_buffer.size();
        } else {
            // Note that BIP324Cipher::EXPANSION is the total difference between contents size
            // and encoded packet size, which includes the 3 bytes due to the packet length.
            // When transitioning from receiving the packet length to receiving its ciphertext,
            // the encrypted packet length is left in the receive buffer.
            return BIP324Cipher::EXPANSION + m_recv_len - m_recv_buffer.size();
        }
    case RecvState::APP_READY:
        // No bytes can be processed until GetMessage() is called.
        return 0;
    case RecvState::V1:
        // Not allowed (must be dealt with by the caller).
        Assume(false);
        return 0;
    }
    Assume(false); // unreachable
    return 0;
}

bool V2Transport::ReceivedBytes(Span<const uint8_t>& msg_bytes) noexcept
{
    AssertLockNotHeld(m_recv_mutex);
    /** How many bytes to allocate in the receive buffer at most above what is received so far. */
    static constexpr size_t MAX_RESERVE_AHEAD = 256 * 1024;

    LOCK(m_recv_mutex);
    if (m_recv_state == RecvState::V1) return m_v1_fallback.ReceivedBytes(msg_bytes);

    // Process the provided bytes in msg_bytes in a loop. In each iteration a nonzero number of
    // bytes (decided by GetMaxBytesToProcess) are taken from the beginning om msg_bytes, and
    // appended to m_recv_buffer. Then, depending on the receiver state, one of the
    // ProcessReceived*Bytes functions is called to process the bytes in that buffer.
    while (!msg_bytes.empty()) {
        // Decide how many bytes to copy from msg_bytes to m_recv_buffer.
        size_t max_read = GetMaxBytesToProcess();

        // Reserve space in the buffer if there is not enough.
        if (m_recv_buffer.size() + std::min(msg_bytes.size(), max_read) > m_recv_buffer.capacity()) {
            switch (m_recv_state) {
            case RecvState::KEY_MAYBE_V1:
            case RecvState::KEY:
            case RecvState::GARB_GARBTERM:
                // During the initial states (key/garbage), allocate once to fit the maximum (4111
                // bytes).
                m_recv_buffer.reserve(MAX_GARBAGE_LEN + BIP324Cipher::GARBAGE_TERMINATOR_LEN);
                break;
            case RecvState::VERSION:
            case RecvState::APP: {
                // During states where a packet is being received, as much as is expected but never
                // more than MAX_RESERVE_AHEAD bytes in addition to what is received so far.
                // This means attackers that want to cause us to waste allocated memory are limited
                // to MAX_RESERVE_AHEAD above the largest allowed message contents size, and to
                // MAX_RESERVE_AHEAD more than they've actually sent us.
                size_t alloc_add = std::min(max_read, msg_bytes.size() + MAX_RESERVE_AHEAD);
                m_recv_buffer.reserve(m_recv_buffer.size() + alloc_add);
                break;
            }
            case RecvState::APP_READY:
                // The buffer is empty in this state.
                Assume(m_recv_buffer.empty());
                break;
            case RecvState::V1:
                // Should have bailed out above.
                Assume(false);
                break;
            }
        }

        // Can't read more than provided input.
        max_read = std::min(msg_bytes.size(), max_read);
        // Copy data to buffer.
        m_recv_buffer.insert(m_recv_buffer.end(), UCharCast(msg_bytes.data()), UCharCast(msg_bytes.data() + max_read));
        msg_bytes = msg_bytes.subspan(max_read);

        // Process data in the buffer.
        switch (m_recv_state) {
        case RecvState::KEY_MAYBE_V1:
            ProcessReceivedMaybeV1Bytes();
            if (m_recv_state == RecvState::V1) return true;
            break;

        case RecvState::KEY:
            if (!ProcessReceivedKeyBytes()) return false;
            break;

        case RecvState::GARB_GARBTERM:
            if (!ProcessReceivedGarbageBytes()) return false;
            break;

        case RecvState::VERSION:
        case RecvState::APP:
            if (!ProcessReceivedPacketBytes()) return false;
            break;

        case RecvState::APP_READY:
            return true;

        case RecvState::V1:
            // We should have bailed out before.
            Assume(false);
            break;
        }
        // Make sure we have made progress before continuing.
        Assume(max_read > 0);
    }

    return true;
}

std::optional<std::string> V2Transport::GetMessageType(Span<const uint8_t>& contents) noexcept
{
    if (contents.size() == 0) return std::nullopt; // Empty contents
    uint8_t first_byte = contents[0];
    contents = contents.subspan(1); // Strip first byte.

    if (first_byte != 0) {
        // Short (1 byte) encoding.
        if (first_byte < std::size(V2_MESSAGE_IDS)) {
            // Valid short message id.
            return V2_MESSAGE_IDS[first_byte];
        } else {
            // Unknown short message id.
            return std::nullopt;
        }
    }

    if (contents.size() < CMessageHeader::COMMAND_SIZE) {
        return std::nullopt; // Long encoding needs 12 message type bytes.
    }

    size_t msg_type_len{0};
    while (msg_type_len < CMessageHeader::COMMAND_SIZE && contents[msg_type_len] != 0) {
        // Verify that message type bytes before the first 0x00 are in range.
        if (contents[msg_type_len] < ' ' || contents[msg_type_len] > 0x7F) {
            return {};
        }
        ++msg_type_len;
    }
    std::string ret{reinterpret_cast<const char*>(contents.data()), msg_type_len};
    while (msg_type_len < CMessageHeader::COMMAND_SIZE) {
        // Verify that message type bytes after the first 0x00 are also 0x00.
        if (contents[msg_type_len] != 0) return {};
        ++msg_type_len;
    }
    // Strip message type bytes of contents.
    contents = contents.subspan(CMessageHeader::COMMAND_SIZE);
    return ret;
}

CNetMessage V2Transport::GetReceivedMessage(std::chrono::microseconds time, bool& reject_message) noexcept
{
    AssertLockNotHeld(m_recv_mutex);
    LOCK(m_recv_mutex);
    if (m_recv_state == RecvState::V1) return m_v1_fallback.GetReceivedMessage(time, reject_message);

    Assume(m_recv_state == RecvState::APP_READY);
    Span<const uint8_t> contents{m_recv_decode_buffer};
    auto msg_type = GetMessageType(contents);
    CNetMessage msg{DataStream{}};
    // Note that BIP324Cipher::EXPANSION also includes the length descriptor size.
    msg.m_raw_message_size = m_recv_decode_buffer.size() + BIP324Cipher::EXPANSION;
    if (msg_type) {
        reject_message = false;
        msg.m_type = std::move(*msg_type);
        msg.m_time = time;
        msg.m_message_size = contents.size();
        msg.m_recv.resize(contents.size());
        std::copy(contents.begin(), contents.end(), UCharCast(msg.m_recv.data()));
    } else {
        LogPrint(BCLog::NET, "V2 transport error: invalid message type (%u bytes contents), peer=%d\n", m_recv_decode_buffer.size(), m_nodeid);
        reject_message = true;
    }
    ClearShrink(m_recv_decode_buffer);
    SetReceiveState(RecvState::APP);

    return msg;
}

bool V2Transport::SetMessageToSend(CSerializedNetMsg& msg) noexcept
{
    AssertLockNotHeld(m_send_mutex);
    LOCK(m_send_mutex);
    if (m_send_state == SendState::V1) return m_v1_fallback.SetMessageToSend(msg);
    // We only allow adding a new message to be sent when in the READY state (so the packet cipher
    // is available) and the send buffer is empty. This limits the number of messages in the send
    // buffer to just one, and leaves the responsibility for queueing them up to the caller.
    if (!(m_send_state == SendState::READY && m_send_buffer.empty())) return false;
    // Construct contents (encoding message type + payload).
    std::vector<uint8_t> contents;
    auto short_message_id = V2_MESSAGE_MAP(msg.m_type);
    if (short_message_id) {
        contents.resize(1 + msg.data.size());
        contents[0] = *short_message_id;
        std::copy(msg.data.begin(), msg.data.end(), contents.begin() + 1);
    } else {
        // Initialize with zeroes, and then write the message type string starting at offset 1.
        // This means contents[0] and the unused positions in contents[1..13] remain 0x00.
        contents.resize(1 + CMessageHeader::COMMAND_SIZE + msg.data.size(), 0);
        std::copy(msg.m_type.begin(), msg.m_type.end(), contents.data() + 1);
        std::copy(msg.data.begin(), msg.data.end(), contents.begin() + 1 + CMessageHeader::COMMAND_SIZE);
    }
    // Construct ciphertext in send buffer.
    m_send_buffer.resize(contents.size() + BIP324Cipher::EXPANSION);
    m_cipher.Encrypt(MakeByteSpan(contents), {}, false, MakeWritableByteSpan(m_send_buffer));
    m_send_type = msg.m_type;
    // Release memory
    ClearShrink(msg.data);
    return true;
}

Transport::BytesToSend V2Transport::GetBytesToSend(bool have_next_message) const noexcept
{
    AssertLockNotHeld(m_send_mutex);
    LOCK(m_send_mutex);
    if (m_send_state == SendState::V1) return m_v1_fallback.GetBytesToSend(have_next_message);

    if (m_send_state == SendState::MAYBE_V1) Assume(m_send_buffer.empty());
    Assume(m_send_pos <= m_send_buffer.size());
    return {
        Span{m_send_buffer}.subspan(m_send_pos),
        // We only have more to send after the current m_send_buffer if there is a (next)
        // message to be sent, and we're capable of sending packets. */
        have_next_message && m_send_state == SendState::READY,
        m_send_type
    };
}

void V2Transport::MarkBytesSent(size_t bytes_sent) noexcept
{
    AssertLockNotHeld(m_send_mutex);
    LOCK(m_send_mutex);
    if (m_send_state == SendState::V1) return m_v1_fallback.MarkBytesSent(bytes_sent);

    if (m_send_state == SendState::AWAITING_KEY && m_send_pos == 0 && bytes_sent > 0) {
        LogPrint(BCLog::NET, "start sending v2 handshake to peer=%d\n", m_nodeid);
    }

    m_send_pos += bytes_sent;
    Assume(m_send_pos <= m_send_buffer.size());
    if (m_send_pos >= CMessageHeader::HEADER_SIZE) {
        m_sent_v1_header_worth = true;
    }
    // Wipe the buffer when everything is sent.
    if (m_send_pos == m_send_buffer.size()) {
        m_send_pos = 0;
        ClearShrink(m_send_buffer);
    }
}

bool V2Transport::ShouldReconnectV1() const noexcept
{
    AssertLockNotHeld(m_send_mutex);
    AssertLockNotHeld(m_recv_mutex);
    // Only outgoing connections need reconnection.
    if (!m_initiating) return false;

    LOCK(m_recv_mutex);
    // We only reconnect in the very first state and when the receive buffer is empty. Together
    // these conditions imply nothing has been received so far.
    if (m_recv_state != RecvState::KEY) return false;
    if (!m_recv_buffer.empty()) return false;
    // Check if we've sent enough for the other side to disconnect us (if it was V1).
    LOCK(m_send_mutex);
    return m_sent_v1_header_worth;
}

size_t V2Transport::GetSendMemoryUsage() const noexcept
{
    AssertLockNotHeld(m_send_mutex);
    LOCK(m_send_mutex);
    if (m_send_state == SendState::V1) return m_v1_fallback.GetSendMemoryUsage();

    return sizeof(m_send_buffer) + memusage::DynamicUsage(m_send_buffer);
}

Transport::Info V2Transport::GetInfo() const noexcept
{
    AssertLockNotHeld(m_recv_mutex);
    LOCK(m_recv_mutex);
    if (m_recv_state == RecvState::V1) return m_v1_fallback.GetInfo();

    Transport::Info info;

    // Do not report v2 and session ID until the version packet has been received
    // and verified (confirming that the other side very likely has the same keys as us).
    if (m_recv_state != RecvState::KEY_MAYBE_V1 && m_recv_state != RecvState::KEY &&
        m_recv_state != RecvState::GARB_GARBTERM && m_recv_state != RecvState::VERSION) {
        info.transport_type = TransportProtocolType::V2;
        info.session_id = uint256(MakeUCharSpan(m_cipher.GetSessionID()));
    } else {
        info.transport_type = TransportProtocolType::DETECTING;
    }

    return info;
}

std::pair<size_t, bool> CConnman::SocketSendData(CNode& node) const
{
    auto it = node.vSendMsg.begin();
    size_t nSentSize = 0;
    bool data_left{false}; //!< second return value (whether unsent data remains)
    std::optional<bool> expected_more;

    while (true) {
        if (it != node.vSendMsg.end()) {
            // If possible, move one message from the send queue to the transport. This fails when
            // there is an existing message still being sent, or (for v2 transports) when the
            // handshake has not yet completed.
            size_t memusage = it->GetMemoryUsage();
            if (node.m_transport->SetMessageToSend(*it)) {
                // Update memory usage of send buffer (as *it will be deleted).
                node.m_send_memusage -= memusage;
                ++it;
            }
        }
        const auto& [data, more, msg_type] = node.m_transport->GetBytesToSend(it != node.vSendMsg.end());
        // We rely on the 'more' value returned by GetBytesToSend to correctly predict whether more
        // bytes are still to be sent, to correctly set the MSG_MORE flag. As a sanity check,
        // verify that the previously returned 'more' was correct.
        if (expected_more.has_value()) Assume(!data.empty() == *expected_more);
        expected_more = more;
        data_left = !data.empty(); // will be overwritten on next loop if all of data gets sent
        int nBytes = 0;
        if (!data.empty()) {
            LOCK(node.m_sock_mutex);
            // There is no socket in case we've already disconnected, or in test cases without
            // real connections. In these cases, we bail out immediately and just leave things
            // in the send queue and transport.
            if (!node.m_sock) {
                break;
            }
            int flags = MSG_NOSIGNAL | MSG_DONTWAIT;
#ifdef MSG_MORE
            if (more) {
                flags |= MSG_MORE;
            }
#endif
            nBytes = node.m_sock->Send(reinterpret_cast<const char*>(data.data()), data.size(), flags);
        }
        if (nBytes > 0) {
            node.m_last_send = GetTime<std::chrono::seconds>();
            node.nSendBytes += nBytes;
            // Notify transport that bytes have been processed.
            node.m_transport->MarkBytesSent(nBytes);
            // Update statistics per message type.
            if (!msg_type.empty()) { // don't report v2 handshake bytes for now
                node.AccountForSentBytes(msg_type, nBytes);
            }
            nSentSize += nBytes;
            if ((size_t)nBytes != data.size()) {
                // could not send full message; stop sending more
                break;
            }
        } else {
            if (nBytes < 0) {
                // error
                int nErr = WSAGetLastError();
                if (nErr != WSAEWOULDBLOCK && nErr != WSAEMSGSIZE && nErr != WSAEINTR && nErr != WSAEINPROGRESS) {
                    LogPrint(BCLog::NET, "socket send error for peer=%d: %s\n", node.GetId(), NetworkErrorString(nErr));
                    node.CloseSocketDisconnect();
                }
            }
            break;
        }
    }

    node.fPauseSend = node.m_send_memusage + node.m_transport->GetSendMemoryUsage() > nSendBufferMaxSize;

    if (it == node.vSendMsg.end()) {
        assert(node.m_send_memusage == 0);
    }
    node.vSendMsg.erase(node.vSendMsg.begin(), it);
    return {nSentSize, data_left};
}

/** Try to find a connection to evict when the node is full.
 *  Extreme care must be taken to avoid opening the node to attacker
 *   triggered network partitioning.
 *  The strategy used here is to protect a small number of peers
 *   for each of several distinct characteristics which are difficult
 *   to forge.  In order to partition a node the attacker must be
 *   simultaneously better at all of them than honest peers.
 */
bool CConnman::AttemptToEvictConnection()
{
    std::vector<NodeEvictionCandidate> vEvictionCandidates;
    {

        LOCK(m_nodes_mutex);
        for (const CNode* node : m_nodes) {
            if (node->fDisconnect)
                continue;
            NodeEvictionCandidate candidate{
                .id = node->GetId(),
                .m_connected = node->m_connected,
                .m_min_ping_time = node->m_min_ping_time,
                .m_last_block_time = node->m_last_block_time,
                .m_last_tx_time = node->m_last_tx_time,
                .fRelevantServices = node->m_has_all_wanted_services,
                .m_relay_txs = node->m_relays_txs.load(),
                .fBloomFilter = node->m_bloom_filter_loaded.load(),
                .nKeyedNetGroup = node->nKeyedNetGroup,
                .prefer_evict = node->m_prefer_evict,
                .m_is_local = node->addr.IsLocal(),
                .m_network = node->ConnectedThroughNetwork(),
                .m_noban = node->HasPermission(NetPermissionFlags::NoBan),
                .m_conn_type = node->m_conn_type,
            };
            vEvictionCandidates.push_back(candidate);
        }
    }
    const std::optional<NodeId> node_id_to_evict = SelectNodeToEvict(std::move(vEvictionCandidates));
    if (!node_id_to_evict) {
        return false;
    }
    LOCK(m_nodes_mutex);
    for (CNode* pnode : m_nodes) {
        if (pnode->GetId() == *node_id_to_evict) {
            LogPrint(BCLog::NET, "selected %s connection for eviction peer=%d; disconnecting\n", pnode->ConnectionTypeAsString(), pnode->GetId());
            pnode->fDisconnect = true;
            return true;
        }
    }
    return false;
}

void CConnman::AcceptConnection(const ListenSocket& hListenSocket) {
    struct sockaddr_storage sockaddr;
    socklen_t len = sizeof(sockaddr);
    auto sock = hListenSocket.sock->Accept((struct sockaddr*)&sockaddr, &len);
    CAddress addr;

    if (!sock) {
        const int nErr = WSAGetLastError();
        if (nErr != WSAEWOULDBLOCK) {
            LogPrintf("socket error accept failed: %s\n", NetworkErrorString(nErr));
        }
        return;
    }

    if (!addr.SetSockAddr((const struct sockaddr*)&sockaddr)) {
        LogPrintLevel(BCLog::NET, BCLog::Level::Warning, "Unknown socket family\n");
    } else {
        addr = CAddress{MaybeFlipIPv6toCJDNS(addr), NODE_NONE};
    }

    const CAddress addr_bind{MaybeFlipIPv6toCJDNS(GetBindAddress(*sock)), NODE_NONE};

    NetPermissionFlags permission_flags = NetPermissionFlags::None;
    hListenSocket.AddSocketPermissionFlags(permission_flags);

    CreateNodeFromAcceptedSocket(std::move(sock), permission_flags, addr_bind, addr);
}

void CConnman::CreateNodeFromAcceptedSocket(std::unique_ptr<Sock>&& sock,
                                            NetPermissionFlags permission_flags,
                                            const CAddress& addr_bind,
                                            const CAddress& addr)
{
    int nInbound = 0;

    AddWhitelistPermissionFlags(permission_flags, addr, vWhitelistedRangeIncoming);

    {
        LOCK(m_nodes_mutex);
        for (const CNode* pnode : m_nodes) {
            if (pnode->IsInboundConn()) nInbound++;
        }
    }

    if (!fNetworkActive) {
        LogPrint(BCLog::NET, "connection from %s dropped: not accepting new connections\n", addr.ToStringAddrPort());
        return;
    }

    if (!sock->IsSelectable()) {
        LogPrintf("connection from %s dropped: non-selectable socket\n", addr.ToStringAddrPort());
        return;
    }

    // According to the internet TCP_NODELAY is not carried into accepted sockets
    // on all platforms.  Set it again here just to be sure.
    const int on{1};
    if (sock->SetSockOpt(IPPROTO_TCP, TCP_NODELAY, &on, sizeof(on)) == SOCKET_ERROR) {
        LogPrint(BCLog::NET, "connection from %s: unable to set TCP_NODELAY, continuing anyway\n",
                 addr.ToStringAddrPort());
    }

    // Don't accept connections from banned peers.
    bool banned = m_banman && m_banman->IsBanned(addr);
    if (!NetPermissions::HasFlag(permission_flags, NetPermissionFlags::NoBan) && banned)
    {
        LogPrint(BCLog::NET, "connection from %s dropped (banned)\n", addr.ToStringAddrPort());
        return;
    }

    // Only accept connections from discouraged peers if our inbound slots aren't (almost) full.
    bool discouraged = m_banman && m_banman->IsDiscouraged(addr);
    if (!NetPermissions::HasFlag(permission_flags, NetPermissionFlags::NoBan) && nInbound + 1 >= m_max_inbound && discouraged)
    {
        LogPrint(BCLog::NET, "connection from %s dropped (discouraged)\n", addr.ToStringAddrPort());
        return;
    }

    if (nInbound >= m_max_inbound)
    {
        if (!AttemptToEvictConnection()) {
            // No connection to evict, disconnect the new connection
            LogPrint(BCLog::NET, "failed to find an eviction candidate - connection dropped (full)\n");
            return;
        }
    }

    NodeId id = GetNewNodeId();
    uint64_t nonce = GetDeterministicRandomizer(RANDOMIZER_ID_LOCALHOSTNONCE).Write(id).Finalize();

    const bool inbound_onion = std::find(m_onion_binds.begin(), m_onion_binds.end(), addr_bind) != m_onion_binds.end();
    // The V2Transport transparently falls back to V1 behavior when an incoming V1 connection is
    // detected, so use it whenever we signal NODE_P2P_V2.
    const bool use_v2transport(nLocalServices & NODE_P2P_V2);

    CNode* pnode = new CNode(id,
                             std::move(sock),
                             addr,
                             CalculateKeyedNetGroup(addr),
                             nonce,
                             addr_bind,
                             /*addrNameIn=*/"",
                             ConnectionType::INBOUND,
                             inbound_onion,
                             CNodeOptions{
                                 .permission_flags = permission_flags,
                                 .prefer_evict = discouraged,
                                 .recv_flood_size = nReceiveFloodSize,
                                 .use_v2transport = use_v2transport,
                             });
    pnode->AddRef();
    m_msgproc->InitializeNode(*pnode, nLocalServices);
    {
        LOCK(m_nodes_mutex);
        m_nodes.push_back(pnode);
    }
    LogDebug(BCLog::NET, "connection from %s accepted\n", addr.ToStringAddrPort());

    // We received a new connection, harvest entropy from the time (and our peer count)
    RandAddEvent((uint32_t)id);
}

bool CConnman::AddConnection(const std::string& address, ConnectionType conn_type, bool use_v2transport = false)
{
    AssertLockNotHeld(m_unused_i2p_sessions_mutex);
    std::optional<int> max_connections;
    switch (conn_type) {
    case ConnectionType::INBOUND:
    case ConnectionType::MANUAL:
        return false;
    case ConnectionType::OUTBOUND_FULL_RELAY:
        max_connections = m_max_outbound_full_relay;
        break;
    case ConnectionType::BLOCK_RELAY:
        max_connections = m_max_outbound_block_relay;
        break;
    // no limit for ADDR_FETCH because -seednode has no limit either
    case ConnectionType::ADDR_FETCH:
        break;
    // no limit for FEELER connections since they're short-lived
    case ConnectionType::FEELER:
        break;
    } // no default case, so the compiler can warn about missing cases

    // Count existing connections
    int existing_connections = WITH_LOCK(m_nodes_mutex,
                                         return std::count_if(m_nodes.begin(), m_nodes.end(), [conn_type](CNode* node) { return node->m_conn_type == conn_type; }););

    // Max connections of specified type already exist
    if (max_connections != std::nullopt && existing_connections >= max_connections) return false;

    // Max total outbound connections already exist
    CSemaphoreGrant grant(*semOutbound, true);
    if (!grant) return false;

    OpenNetworkConnection(CAddress(), false, std::move(grant), address.c_str(), conn_type, /*use_v2transport=*/use_v2transport);
    return true;
}

void CConnman::DisconnectNodes()
{
    AssertLockNotHeld(m_nodes_mutex);
    AssertLockNotHeld(m_reconnections_mutex);

    // Use a temporary variable to accumulate desired reconnections, so we don't need
    // m_reconnections_mutex while holding m_nodes_mutex.
    decltype(m_reconnections) reconnections_to_add;

    {
        LOCK(m_nodes_mutex);

        if (!fNetworkActive) {
            // Disconnect any connected nodes
            for (CNode* pnode : m_nodes) {
                if (!pnode->fDisconnect) {
                    LogPrint(BCLog::NET, "Network not active, dropping peer=%d\n", pnode->GetId());
                    pnode->fDisconnect = true;
                }
            }
        }

        // Disconnect unused nodes
        std::vector<CNode*> nodes_copy = m_nodes;
        for (CNode* pnode : nodes_copy)
        {
            if (pnode->fDisconnect)
            {
                // remove from m_nodes
                m_nodes.erase(remove(m_nodes.begin(), m_nodes.end(), pnode), m_nodes.end());

                // Add to reconnection list if appropriate. We don't reconnect right here, because
                // the creation of a connection is a blocking operation (up to several seconds),
                // and we don't want to hold up the socket handler thread for that long.
                if (pnode->m_transport->ShouldReconnectV1()) {
                    reconnections_to_add.push_back({
                        .addr_connect = pnode->addr,
                        .grant = std::move(pnode->grantOutbound),
                        .destination = pnode->m_dest,
                        .conn_type = pnode->m_conn_type,
                        .use_v2transport = false});
                    LogPrint(BCLog::NET, "retrying with v1 transport protocol for peer=%d\n", pnode->GetId());
                }

                // release outbound grant (if any)
                pnode->grantOutbound.Release();

                // close socket and cleanup
                pnode->CloseSocketDisconnect();

                // update connection count by network
                if (pnode->IsManualOrFullOutboundConn()) --m_network_conn_counts[pnode->addr.GetNetwork()];

                // hold in disconnected pool until all refs are released
                pnode->Release();
                m_nodes_disconnected.push_back(pnode);
            }
        }
    }
    {
        // Delete disconnected nodes
        std::list<CNode*> nodes_disconnected_copy = m_nodes_disconnected;
        for (CNode* pnode : nodes_disconnected_copy)
        {
            // Destroy the object only after other threads have stopped using it.
            if (pnode->GetRefCount() <= 0) {
                m_nodes_disconnected.remove(pnode);
                DeleteNode(pnode);
            }
        }
    }
    {
        // Move entries from reconnections_to_add to m_reconnections.
        LOCK(m_reconnections_mutex);
        m_reconnections.splice(m_reconnections.end(), std::move(reconnections_to_add));
    }
}

void CConnman::NotifyNumConnectionsChanged()
{
    size_t nodes_size;
    {
        LOCK(m_nodes_mutex);
        nodes_size = m_nodes.size();
    }
    if(nodes_size != nPrevNodeCount) {
        nPrevNodeCount = nodes_size;
        if (m_client_interface) {
            m_client_interface->NotifyNumConnectionsChanged(nodes_size);
        }
    }
}

bool CConnman::ShouldRunInactivityChecks(const CNode& node, std::chrono::seconds now) const
{
    return node.m_connected + m_peer_connect_timeout < now;
}

bool CConnman::InactivityCheck(const CNode& node) const
{
    // Tests that see disconnects after using mocktime can start nodes with a
    // large timeout. For example, -peertimeout=999999999.
    const auto now{GetTime<std::chrono::seconds>()};
    const auto last_send{node.m_last_send.load()};
    const auto last_recv{node.m_last_recv.load()};

    if (!ShouldRunInactivityChecks(node, now)) return false;

    if (last_recv.count() == 0 || last_send.count() == 0) {
        LogPrint(BCLog::NET, "socket no message in first %i seconds, %d %d peer=%d\n", count_seconds(m_peer_connect_timeout), last_recv.count() != 0, last_send.count() != 0, node.GetId());
        return true;
    }

    if (now > last_send + TIMEOUT_INTERVAL) {
        LogPrint(BCLog::NET, "socket sending timeout: %is peer=%d\n", count_seconds(now - last_send), node.GetId());
        return true;
    }

    if (now > last_recv + TIMEOUT_INTERVAL) {
        LogPrint(BCLog::NET, "socket receive timeout: %is peer=%d\n", count_seconds(now - last_recv), node.GetId());
        return true;
    }

    if (!node.fSuccessfullyConnected) {
        if (node.m_transport->GetInfo().transport_type == TransportProtocolType::DETECTING) {
            LogPrint(BCLog::NET, "V2 handshake timeout peer=%d\n", node.GetId());
        } else {
            LogPrint(BCLog::NET, "version handshake timeout peer=%d\n", node.GetId());
        }
        return true;
    }

    return false;
}

Sock::EventsPerSock CConnman::GenerateWaitSockets(Span<CNode* const> nodes)
{
    Sock::EventsPerSock events_per_sock;

    for (const ListenSocket& hListenSocket : vhListenSocket) {
        events_per_sock.emplace(hListenSocket.sock, Sock::Events{Sock::RECV});
    }

    for (CNode* pnode : nodes) {
        bool select_recv = !pnode->fPauseRecv;
        bool select_send;
        {
            LOCK(pnode->cs_vSend);
            // Sending is possible if either there are bytes to send right now, or if there will be
            // once a potential message from vSendMsg is handed to the transport. GetBytesToSend
            // determines both of these in a single call.
            const auto& [to_send, more, _msg_type] = pnode->m_transport->GetBytesToSend(!pnode->vSendMsg.empty());
            select_send = !to_send.empty() || more;
        }
        if (!select_recv && !select_send) continue;

        LOCK(pnode->m_sock_mutex);
        if (pnode->m_sock) {
            Sock::Event event = (select_send ? Sock::SEND : 0) | (select_recv ? Sock::RECV : 0);
            events_per_sock.emplace(pnode->m_sock, Sock::Events{event});
        }
    }

    return events_per_sock;
}

void CConnman::SocketHandler()
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);

    Sock::EventsPerSock events_per_sock;

    {
        const NodesSnapshot snap{*this, /*shuffle=*/false};

        const auto timeout = std::chrono::milliseconds(SELECT_TIMEOUT_MILLISECONDS);

        // Check for the readiness of the already connected sockets and the
        // listening sockets in one call ("readiness" as in poll(2) or
        // select(2)). If none are ready, wait for a short while and return
        // empty sets.
        events_per_sock = GenerateWaitSockets(snap.Nodes());
        if (events_per_sock.empty() || !events_per_sock.begin()->first->WaitMany(timeout, events_per_sock)) {
            interruptNet.sleep_for(timeout);
        }

        // Service (send/receive) each of the already connected nodes.
        SocketHandlerConnected(snap.Nodes(), events_per_sock);
    }

    // Accept new connections from listening sockets.
    SocketHandlerListening(events_per_sock);
}

void CConnman::SocketHandlerConnected(const std::vector<CNode*>& nodes,
                                      const Sock::EventsPerSock& events_per_sock)
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);

    for (CNode* pnode : nodes) {
        if (interruptNet)
            return;

        //
        // Receive
        //
        bool recvSet = false;
        bool sendSet = false;
        bool errorSet = false;
        {
            LOCK(pnode->m_sock_mutex);
            if (!pnode->m_sock) {
                continue;
            }
            const auto it = events_per_sock.find(pnode->m_sock);
            if (it != events_per_sock.end()) {
                recvSet = it->second.occurred & Sock::RECV;
                sendSet = it->second.occurred & Sock::SEND;
                errorSet = it->second.occurred & Sock::ERR;
            }
        }

        if (sendSet) {
            // Send data
            auto [bytes_sent, data_left] = WITH_LOCK(pnode->cs_vSend, return SocketSendData(*pnode));
            if (bytes_sent) {
                RecordBytesSent(bytes_sent);

                // If both receiving and (non-optimistic) sending were possible, we first attempt
                // sending. If that succeeds, but does not fully drain the send queue, do not
                // attempt to receive. This avoids needlessly queueing data if the remote peer
                // is slow at receiving data, by means of TCP flow control. We only do this when
                // sending actually succeeded to make sure progress is always made; otherwise a
                // deadlock would be possible when both sides have data to send, but neither is
                // receiving.
                if (data_left) recvSet = false;
            }
        }

        if (recvSet || errorSet)
        {
            // typical socket buffer is 8K-64K
            uint8_t pchBuf[0x10000];
            int nBytes = 0;
            {
                LOCK(pnode->m_sock_mutex);
                if (!pnode->m_sock) {
                    continue;
                }
                nBytes = pnode->m_sock->Recv(pchBuf, sizeof(pchBuf), MSG_DONTWAIT);
            }
            if (nBytes > 0)
            {
                bool notify = false;
                if (!pnode->ReceiveMsgBytes({pchBuf, (size_t)nBytes}, notify)) {
                    pnode->CloseSocketDisconnect();
                }
                RecordBytesRecv(nBytes);
                if (notify) {
                    pnode->MarkReceivedMsgsForProcessing();
                    WakeMessageHandler();
                }
            }
            else if (nBytes == 0)
            {
                // socket closed gracefully
                if (!pnode->fDisconnect) {
                    LogPrint(BCLog::NET, "socket closed for peer=%d\n", pnode->GetId());
                }
                pnode->CloseSocketDisconnect();
            }
            else if (nBytes < 0)
            {
                // error
                int nErr = WSAGetLastError();
                if (nErr != WSAEWOULDBLOCK && nErr != WSAEMSGSIZE && nErr != WSAEINTR && nErr != WSAEINPROGRESS)
                {
                    if (!pnode->fDisconnect) {
                        LogPrint(BCLog::NET, "socket recv error for peer=%d: %s\n", pnode->GetId(), NetworkErrorString(nErr));
                    }
                    pnode->CloseSocketDisconnect();
                }
            }
        }

        if (InactivityCheck(*pnode)) pnode->fDisconnect = true;
    }
}

void CConnman::SocketHandlerListening(const Sock::EventsPerSock& events_per_sock)
{
    for (const ListenSocket& listen_socket : vhListenSocket) {
        if (interruptNet) {
            return;
        }
        const auto it = events_per_sock.find(listen_socket.sock);
        if (it != events_per_sock.end() && it->second.occurred & Sock::RECV) {
            AcceptConnection(listen_socket);
        }
    }
}

void CConnman::ThreadSocketHandler()
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);

    while (!interruptNet)
    {
        DisconnectNodes();
        NotifyNumConnectionsChanged();
        SocketHandler();
    }
}

void CConnman::WakeMessageHandler()
{
    {
        LOCK(mutexMsgProc);
        fMsgProcWake = true;
    }
    condMsgProc.notify_one();
}

void CConnman::ThreadDNSAddressSeed()
{
    constexpr int TARGET_OUTBOUND_CONNECTIONS = 2;
    int outbound_connection_count = 0;

    if (gArgs.IsArgSet("-seednode")) {
        auto start = NodeClock::now();
        constexpr std::chrono::seconds SEEDNODE_TIMEOUT = 30s;
        LogPrintf("-seednode enabled. Trying the provided seeds for %d seconds before defaulting to the dnsseeds.\n", SEEDNODE_TIMEOUT.count());
        while (!interruptNet) {
            if (!interruptNet.sleep_for(std::chrono::milliseconds(500)))
                return;

            // Abort if we have spent enough time without reaching our target.
            // Giving seed nodes 30 seconds so this does not become a race against fixedseeds (which triggers after 1 min)
            if (NodeClock::now() > start + SEEDNODE_TIMEOUT) {
                LogPrintf("Couldn't connect to enough peers via seed nodes. Handing fetch logic to the DNS seeds.\n");
                break;
            }

            outbound_connection_count = GetFullOutboundConnCount();
            if (outbound_connection_count >= TARGET_OUTBOUND_CONNECTIONS) {
                LogPrintf("P2P peers available. Finished fetching data from seed nodes.\n");
                break;
            }
        }
    }

    FastRandomContext rng;
    std::vector<std::string> seeds = m_params.DNSSeeds();
    std::shuffle(seeds.begin(), seeds.end(), rng);
    int seeds_right_now = 0; // Number of seeds left before testing if we have enough connections

    if (gArgs.GetBoolArg("-forcednsseed", DEFAULT_FORCEDNSSEED)) {
        // When -forcednsseed is provided, query all.
        seeds_right_now = seeds.size();
    } else if (addrman.Size() == 0) {
        // If we have no known peers, query all.
        // This will occur on the first run, or if peers.dat has been
        // deleted.
        seeds_right_now = seeds.size();
    }

    // Proceed with dnsseeds if seednodes hasn't reached the target or if forcednsseed is set
    if (outbound_connection_count < TARGET_OUTBOUND_CONNECTIONS || seeds_right_now) {
        // goal: only query DNS seed if address need is acute
        // * If we have a reasonable number of peers in addrman, spend
        //   some time trying them first. This improves user privacy by
        //   creating fewer identifying DNS requests, reduces trust by
        //   giving seeds less influence on the network topology, and
        //   reduces traffic to the seeds.
        // * When querying DNS seeds query a few at once, this ensures
        //   that we don't give DNS seeds the ability to eclipse nodes
        //   that query them.
        // * If we continue having problems, eventually query all the
        //   DNS seeds, and if that fails too, also try the fixed seeds.
        //   (done in ThreadOpenConnections)
        int found = 0;
        const std::chrono::seconds seeds_wait_time = (addrman.Size() >= DNSSEEDS_DELAY_PEER_THRESHOLD ? DNSSEEDS_DELAY_MANY_PEERS : DNSSEEDS_DELAY_FEW_PEERS);

        for (const std::string& seed : seeds) {
            if (seeds_right_now == 0) {
                seeds_right_now += DNSSEEDS_TO_QUERY_AT_ONCE;

                if (addrman.Size() > 0) {
                    LogPrintf("Waiting %d seconds before querying DNS seeds.\n", seeds_wait_time.count());
                    std::chrono::seconds to_wait = seeds_wait_time;
                    while (to_wait.count() > 0) {
                        // if sleeping for the MANY_PEERS interval, wake up
                        // early to see if we have enough peers and can stop
                        // this thread entirely freeing up its resources
                        std::chrono::seconds w = std::min(DNSSEEDS_DELAY_FEW_PEERS, to_wait);
                        if (!interruptNet.sleep_for(w)) return;
                        to_wait -= w;

                        if (GetFullOutboundConnCount() >= TARGET_OUTBOUND_CONNECTIONS) {
                            if (found > 0) {
                                LogPrintf("%d addresses found from DNS seeds\n", found);
                                LogPrintf("P2P peers available. Finished DNS seeding.\n");
                            } else {
                                LogPrintf("P2P peers available. Skipped DNS seeding.\n");
                            }
                            return;
                        }
                    }
                }
            }

            if (interruptNet) return;

            // hold off on querying seeds if P2P network deactivated
            if (!fNetworkActive) {
                LogPrintf("Waiting for network to be reactivated before querying DNS seeds.\n");
                do {
                    if (!interruptNet.sleep_for(std::chrono::seconds{1})) return;
                } while (!fNetworkActive);
            }

            LogPrintf("Loading addresses from DNS seed %s\n", seed);
            // If -proxy is in use, we make an ADDR_FETCH connection to the DNS resolved peer address
            // for the base dns seed domain in chainparams
            if (HaveNameProxy()) {
                AddAddrFetch(seed);
            } else {
                std::vector<CAddress> vAdd;
                constexpr ServiceFlags requiredServiceBits{SeedsServiceFlags()};
                std::string host = strprintf("x%x.%s", requiredServiceBits, seed);
                CNetAddr resolveSource;
                if (!resolveSource.SetInternal(host)) {
                    continue;
                }
                // Limit number of IPs learned from a single DNS seed. This limit exists to prevent the results from
                // one DNS seed from dominating AddrMan. Note that the number of results from a UDP DNS query is
                // bounded to 33 already, but it is possible for it to use TCP where a larger number of results can be
                // returned.
                unsigned int nMaxIPs = 32;
                const auto addresses{LookupHost(host, nMaxIPs, true)};
                if (!addresses.empty()) {
                    for (const CNetAddr& ip : addresses) {
                        CAddress addr = CAddress(CService(ip, m_params.GetDefaultPort()), requiredServiceBits);
                        addr.nTime = rng.rand_uniform_delay(Now<NodeSeconds>() - 3 * 24h, -4 * 24h); // use a random age between 3 and 7 days old
                        vAdd.push_back(addr);
                        found++;
                    }
                    addrman.Add(vAdd, resolveSource);
                } else {
                    // If the seed does not support a subdomain with our desired service bits,
                    // we make an ADDR_FETCH connection to the DNS resolved peer address for the
                    // base dns seed domain in chainparams
                    AddAddrFetch(seed);
                }
            }
            --seeds_right_now;
        }
        LogPrintf("%d addresses found from DNS seeds\n", found);
    } else {
        LogPrintf("Skipping DNS seeds. Enough peers have been found\n");
    }
}

void CConnman::DumpAddresses()
{
    const auto start{SteadyClock::now()};

    DumpPeerAddresses(::gArgs, addrman);

    LogPrint(BCLog::NET, "Flushed %d addresses to peers.dat  %dms\n",
             addrman.Size(), Ticks<std::chrono::milliseconds>(SteadyClock::now() - start));
}

void CConnman::ProcessAddrFetch()
{
    AssertLockNotHeld(m_unused_i2p_sessions_mutex);
    std::string strDest;
    {
        LOCK(m_addr_fetches_mutex);
        if (m_addr_fetches.empty())
            return;
        strDest = m_addr_fetches.front();
        m_addr_fetches.pop_front();
    }
    // Attempt v2 connection if we support v2 - we'll reconnect with v1 if our
    // peer doesn't support it or immediately disconnects us for another reason.
    const bool use_v2transport(GetLocalServices() & NODE_P2P_V2);
    CAddress addr;
    CSemaphoreGrant grant(*semOutbound, /*fTry=*/true);
    if (grant) {
        OpenNetworkConnection(addr, false, std::move(grant), strDest.c_str(), ConnectionType::ADDR_FETCH, use_v2transport);
    }
}

bool CConnman::GetTryNewOutboundPeer() const
{
    return m_try_another_outbound_peer;
}

void CConnman::SetTryNewOutboundPeer(bool flag)
{
    m_try_another_outbound_peer = flag;
    LogPrint(BCLog::NET, "setting try another outbound peer=%s\n", flag ? "true" : "false");
}

void CConnman::StartExtraBlockRelayPeers()
{
    LogPrint(BCLog::NET, "enabling extra block-relay-only peers\n");
    m_start_extra_block_relay_peers = true;
}

// Return the number of outbound connections that are full relay (not blocks only)
int CConnman::GetFullOutboundConnCount() const
{
    int nRelevant = 0;
    {
        LOCK(m_nodes_mutex);
        for (const CNode* pnode : m_nodes) {
            if (pnode->fSuccessfullyConnected && pnode->IsFullOutboundConn()) ++nRelevant;
        }
    }
    return nRelevant;
}

// Return the number of peers we have over our outbound connection limit
// Exclude peers that are marked for disconnect, or are going to be
// disconnected soon (eg ADDR_FETCH and FEELER)
// Also exclude peers that haven't finished initial connection handshake yet
// (so that we don't decide we're over our desired connection limit, and then
// evict some peer that has finished the handshake)
int CConnman::GetExtraFullOutboundCount() const
{
    int full_outbound_peers = 0;
    {
        LOCK(m_nodes_mutex);
        for (const CNode* pnode : m_nodes) {
            if (pnode->fSuccessfullyConnected && !pnode->fDisconnect && pnode->IsFullOutboundConn()) {
                ++full_outbound_peers;
            }
        }
    }
    return std::max(full_outbound_peers - m_max_outbound_full_relay, 0);
}

int CConnman::GetExtraBlockRelayCount() const
{
    int block_relay_peers = 0;
    {
        LOCK(m_nodes_mutex);
        for (const CNode* pnode : m_nodes) {
            if (pnode->fSuccessfullyConnected && !pnode->fDisconnect && pnode->IsBlockOnlyConn()) {
                ++block_relay_peers;
            }
        }
    }
    return std::max(block_relay_peers - m_max_outbound_block_relay, 0);
}

std::unordered_set<Network> CConnman::GetReachableEmptyNetworks() const
{
    std::unordered_set<Network> networks{};
    for (int n = 0; n < NET_MAX; n++) {
        enum Network net = (enum Network)n;
        if (net == NET_UNROUTABLE || net == NET_INTERNAL) continue;
        if (g_reachable_nets.Contains(net) && addrman.Size(net, std::nullopt) == 0) {
            networks.insert(net);
        }
    }
    return networks;
}

bool CConnman::MultipleManualOrFullOutboundConns(Network net) const
{
    AssertLockHeld(m_nodes_mutex);
    return m_network_conn_counts[net] > 1;
}

bool CConnman::MaybePickPreferredNetwork(std::optional<Network>& network)
{
    std::array<Network, 5> nets{NET_IPV4, NET_IPV6, NET_ONION, NET_I2P, NET_CJDNS};
    std::shuffle(nets.begin(), nets.end(), FastRandomContext());

    LOCK(m_nodes_mutex);
    for (const auto net : nets) {
        if (g_reachable_nets.Contains(net) && m_network_conn_counts[net] == 0 && addrman.Size(net) != 0) {
            network = net;
            return true;
        }
    }

    return false;
}

void CConnman::ThreadOpenConnections(const std::vector<std::string> connect)
{
    AssertLockNotHeld(m_unused_i2p_sessions_mutex);
    AssertLockNotHeld(m_reconnections_mutex);
    FastRandomContext rng;
    // Connect to specific addresses
    if (!connect.empty())
    {
        // Attempt v2 connection if we support v2 - we'll reconnect with v1 if our
        // peer doesn't support it or immediately disconnects us for another reason.
        const bool use_v2transport(GetLocalServices() & NODE_P2P_V2);
        for (int64_t nLoop = 0;; nLoop++)
        {
            for (const std::string& strAddr : connect)
            {
                CAddress addr(CService(), NODE_NONE);
                OpenNetworkConnection(addr, false, {}, strAddr.c_str(), ConnectionType::MANUAL, /*use_v2transport=*/use_v2transport);
                for (int i = 0; i < 10 && i < nLoop; i++)
                {
                    if (!interruptNet.sleep_for(std::chrono::milliseconds(500)))
                        return;
                }
            }
            if (!interruptNet.sleep_for(std::chrono::milliseconds(500)))
                return;
            PerformReconnections();
        }
    }

    // Initiate network connections
    auto start = GetTime<std::chrono::microseconds>();

    // Minimum time before next feeler connection (in microseconds).
    auto next_feeler = start + rng.rand_exp_duration(FEELER_INTERVAL);
    auto next_extra_block_relay = start + rng.rand_exp_duration(EXTRA_BLOCK_RELAY_ONLY_PEER_INTERVAL);
    auto next_extra_network_peer{start + rng.rand_exp_duration(EXTRA_NETWORK_PEER_INTERVAL)};
    const bool dnsseed = gArgs.GetBoolArg("-dnsseed", DEFAULT_DNSSEED);
    bool add_fixed_seeds = gArgs.GetBoolArg("-fixedseeds", DEFAULT_FIXEDSEEDS);
    const bool use_seednodes{gArgs.IsArgSet("-seednode")};

    if (!add_fixed_seeds) {
        LogPrintf("Fixed seeds are disabled\n");
    }

    while (!interruptNet)
    {
        ProcessAddrFetch();

        if (!interruptNet.sleep_for(std::chrono::milliseconds(500)))
            return;

        PerformReconnections();

        CSemaphoreGrant grant(*semOutbound);
        if (interruptNet)
            return;

        const std::unordered_set<Network> fixed_seed_networks{GetReachableEmptyNetworks()};
        if (add_fixed_seeds && !fixed_seed_networks.empty()) {
            // When the node starts with an empty peers.dat, there are a few other sources of peers before
            // we fallback on to fixed seeds: -dnsseed, -seednode, -addnode
            // If none of those are available, we fallback on to fixed seeds immediately, else we allow
            // 60 seconds for any of those sources to populate addrman.
            bool add_fixed_seeds_now = false;
            // It is cheapest to check if enough time has passed first.
            if (GetTime<std::chrono::seconds>() > start + std::chrono::minutes{1}) {
                add_fixed_seeds_now = true;
                LogPrintf("Adding fixed seeds as 60 seconds have passed and addrman is empty for at least one reachable network\n");
            }

            // Perform cheap checks before locking a mutex.
            else if (!dnsseed && !use_seednodes) {
                LOCK(m_added_nodes_mutex);
                if (m_added_node_params.empty()) {
                    add_fixed_seeds_now = true;
                    LogPrintf("Adding fixed seeds as -dnsseed=0 (or IPv4/IPv6 connections are disabled via -onlynet) and neither -addnode nor -seednode are provided\n");
                }
            }

            if (add_fixed_seeds_now) {
                std::vector<CAddress> seed_addrs{ConvertSeeds(m_params.FixedSeeds())};
                // We will not make outgoing connections to peers that are unreachable
                // (e.g. because of -onlynet configuration).
                // Therefore, we do not add them to addrman in the first place.
                // In case previously unreachable networks become reachable
                // (e.g. in case of -onlynet changes by the user), fixed seeds will
                // be loaded only for networks for which we have no addresses.
                seed_addrs.erase(std::remove_if(seed_addrs.begin(), seed_addrs.end(),
                                                [&fixed_seed_networks](const CAddress& addr) { return fixed_seed_networks.count(addr.GetNetwork()) == 0; }),
                                 seed_addrs.end());
                CNetAddr local;
                local.SetInternal("fixedseeds");
                addrman.Add(seed_addrs, local);
                add_fixed_seeds = false;
                LogPrintf("Added %d fixed seeds from reachable networks.\n", seed_addrs.size());
            }
        }

        //
        // Choose an address to connect to based on most recently seen
        //
        CAddress addrConnect;

        // Only connect out to one peer per ipv4/ipv6 network group (/16 for IPv4).
        int nOutboundFullRelay = 0;
        int nOutboundBlockRelay = 0;
        int outbound_privacy_network_peers = 0;
        std::set<std::vector<unsigned char>> outbound_ipv46_peer_netgroups;

        {
            LOCK(m_nodes_mutex);
            for (const CNode* pnode : m_nodes) {
                if (pnode->IsFullOutboundConn()) nOutboundFullRelay++;
                if (pnode->IsBlockOnlyConn()) nOutboundBlockRelay++;

                // Make sure our persistent outbound slots to ipv4/ipv6 peers belong to different netgroups.
                switch (pnode->m_conn_type) {
                    // We currently don't take inbound connections into account. Since they are
                    // free to make, an attacker could make them to prevent us from connecting to
                    // certain peers.
                    case ConnectionType::INBOUND:
                    // Short-lived outbound connections should not affect how we select outbound
                    // peers from addrman.
                    case ConnectionType::ADDR_FETCH:
                    case ConnectionType::FEELER:
                        break;
                    case ConnectionType::MANUAL:
                    case ConnectionType::OUTBOUND_FULL_RELAY:
                    case ConnectionType::BLOCK_RELAY:
                        const CAddress address{pnode->addr};
                        if (address.IsTor() || address.IsI2P() || address.IsCJDNS()) {
                            // Since our addrman-groups for these networks are
                            // random, without relation to the route we
                            // take to connect to these peers or to the
                            // difficulty in obtaining addresses with diverse
                            // groups, we don't worry about diversity with
                            // respect to our addrman groups when connecting to
                            // these networks.
                            ++outbound_privacy_network_peers;
                        } else {
                            outbound_ipv46_peer_netgroups.insert(m_netgroupman.GetGroup(address));
                        }
                } // no default case, so the compiler can warn about missing cases
            }
        }

        ConnectionType conn_type = ConnectionType::OUTBOUND_FULL_RELAY;
        auto now = GetTime<std::chrono::microseconds>();
        bool anchor = false;
        bool fFeeler = false;
        std::optional<Network> preferred_net;

        // Determine what type of connection to open. Opening
        // BLOCK_RELAY connections to addresses from anchors.dat gets the highest
        // priority. Then we open OUTBOUND_FULL_RELAY priority until we
        // meet our full-relay capacity. Then we open BLOCK_RELAY connection
        // until we hit our block-relay-only peer limit.
        // GetTryNewOutboundPeer() gets set when a stale tip is detected, so we
        // try opening an additional OUTBOUND_FULL_RELAY connection. If none of
        // these conditions are met, check to see if it's time to try an extra
        // block-relay-only peer (to confirm our tip is current, see below) or the next_feeler
        // timer to decide if we should open a FEELER.

        if (!m_anchors.empty() && (nOutboundBlockRelay < m_max_outbound_block_relay)) {
            conn_type = ConnectionType::BLOCK_RELAY;
            anchor = true;
        } else if (nOutboundFullRelay < m_max_outbound_full_relay) {
            // OUTBOUND_FULL_RELAY
        } else if (nOutboundBlockRelay < m_max_outbound_block_relay) {
            conn_type = ConnectionType::BLOCK_RELAY;
        } else if (GetTryNewOutboundPeer()) {
            // OUTBOUND_FULL_RELAY
        } else if (now > next_extra_block_relay && m_start_extra_block_relay_peers) {
            // Periodically connect to a peer (using regular outbound selection
            // methodology from addrman) and stay connected long enough to sync
            // headers, but not much else.
            //
            // Then disconnect the peer, if we haven't learned anything new.
            //
            // The idea is to make eclipse attacks very difficult to pull off,
            // because every few minutes we're finding a new peer to learn headers
            // from.
            //
            // This is similar to the logic for trying extra outbound (full-relay)
            // peers, except:
            // - we do this all the time on an exponential timer, rather than just when
            //   our tip is stale
            // - we potentially disconnect our next-youngest block-relay-only peer, if our
            //   newest block-relay-only peer delivers a block more recently.
            //   See the eviction logic in net_processing.cpp.
            //
            // Because we can promote these connections to block-relay-only
            // connections, they do not get their own ConnectionType enum
            // (similar to how we deal with extra outbound peers).
            next_extra_block_relay = now + rng.rand_exp_duration(EXTRA_BLOCK_RELAY_ONLY_PEER_INTERVAL);
            conn_type = ConnectionType::BLOCK_RELAY;
        } else if (now > next_feeler) {
            next_feeler = now + rng.rand_exp_duration(FEELER_INTERVAL);
            conn_type = ConnectionType::FEELER;
            fFeeler = true;
        } else if (nOutboundFullRelay == m_max_outbound_full_relay &&
                   m_max_outbound_full_relay == MAX_OUTBOUND_FULL_RELAY_CONNECTIONS &&
                   now > next_extra_network_peer &&
                   MaybePickPreferredNetwork(preferred_net)) {
            // Full outbound connection management: Attempt to get at least one
            // outbound peer from each reachable network by making extra connections
            // and then protecting "only" peers from a network during outbound eviction.
            // This is not attempted if the user changed -maxconnections to a value
            // so low that less than MAX_OUTBOUND_FULL_RELAY_CONNECTIONS are made,
            // to prevent interactions with otherwise protected outbound peers.
            next_extra_network_peer = now + rng.rand_exp_duration(EXTRA_NETWORK_PEER_INTERVAL);
        } else {
            // skip to next iteration of while loop
            continue;
        }

        addrman.ResolveCollisions();

        const auto current_time{NodeClock::now()};
        int nTries = 0;
        while (!interruptNet)
        {
            if (anchor && !m_anchors.empty()) {
                const CAddress addr = m_anchors.back();
                m_anchors.pop_back();
                if (!addr.IsValid() || IsLocal(addr) || !g_reachable_nets.Contains(addr) ||
                    !m_msgproc->HasAllDesirableServiceFlags(addr.nServices) ||
                    outbound_ipv46_peer_netgroups.count(m_netgroupman.GetGroup(addr))) continue;
                addrConnect = addr;
                LogPrint(BCLog::NET, "Trying to make an anchor connection to %s\n", addrConnect.ToStringAddrPort());
                break;
            }

            // If we didn't find an appropriate destination after trying 100 addresses fetched from addrman,
            // stop this loop, and let the outer loop run again (which sleeps, adds seed nodes, recalculates
            // already-connected network ranges, ...) before trying new addrman addresses.
            nTries++;
            if (nTries > 100)
                break;

            CAddress addr;
            NodeSeconds addr_last_try{0s};

            if (fFeeler) {
                // First, try to get a tried table collision address. This returns
                // an empty (invalid) address if there are no collisions to try.
                std::tie(addr, addr_last_try) = addrman.SelectTriedCollision();

                if (!addr.IsValid()) {
                    // No tried table collisions. Select a new table address
                    // for our feeler.
                    std::tie(addr, addr_last_try) = addrman.Select(true);
                } else if (AlreadyConnectedToAddress(addr)) {
                    // If test-before-evict logic would have us connect to a
                    // peer that we're already connected to, just mark that
                    // address as Good(). We won't be able to initiate the
                    // connection anyway, so this avoids inadvertently evicting
                    // a currently-connected peer.
                    addrman.Good(addr);
                    // Select a new table address for our feeler instead.
                    std::tie(addr, addr_last_try) = addrman.Select(true);
                }
            } else {
                // Not a feeler
                // If preferred_net has a value set, pick an extra outbound
                // peer from that network. The eviction logic in net_processing
                // ensures that a peer from another network will be evicted.
                std::tie(addr, addr_last_try) = addrman.Select(false, preferred_net);
            }

            // Require outbound IPv4/IPv6 connections, other than feelers, to be to distinct network groups
            if (!fFeeler && outbound_ipv46_peer_netgroups.count(m_netgroupman.GetGroup(addr))) {
                continue;
            }

            // if we selected an invalid or local address, restart
            if (!addr.IsValid() || IsLocal(addr)) {
                break;
            }

            if (!g_reachable_nets.Contains(addr)) {
                continue;
            }

            // only consider very recently tried nodes after 30 failed attempts
            if (current_time - addr_last_try < 10min && nTries < 30) {
                continue;
            }

            // for non-feelers, require all the services we'll want,
            // for feelers, only require they be a full node (only because most
            // SPV clients don't have a good address DB available)
            if (!fFeeler && !m_msgproc->HasAllDesirableServiceFlags(addr.nServices)) {
                continue;
            } else if (fFeeler && !MayHaveUsefulAddressDB(addr.nServices)) {
                continue;
            }

            // Do not connect to bad ports, unless 50 invalid addresses have been selected already.
            if (nTries < 50 && (addr.IsIPv4() || addr.IsIPv6()) && IsBadPort(addr.GetPort())) {
                continue;
            }

            // Do not make automatic outbound connections to addnode peers, to
            // not use our limited outbound slots for them and to ensure
            // addnode connections benefit from their intended protections.
            if (AddedNodesContain(addr)) {
                LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "Not making automatic %s%s connection to %s peer selected for manual (addnode) connection%s\n",
                              preferred_net.has_value() ? "network-specific " : "",
                              ConnectionTypeAsString(conn_type), GetNetworkName(addr.GetNetwork()),
                              fLogIPs ? strprintf(": %s", addr.ToStringAddrPort()) : "");
                continue;
            }

            addrConnect = addr;
            break;
        }

        if (addrConnect.IsValid()) {
            if (fFeeler) {
                // Add small amount of random noise before connection to avoid synchronization.
                if (!interruptNet.sleep_for(rng.rand_uniform_duration<CThreadInterrupt::Clock>(FEELER_SLEEP_WINDOW))) {
                    return;
                }
                LogPrint(BCLog::NET, "Making feeler connection to %s\n", addrConnect.ToStringAddrPort());
            }

            if (preferred_net != std::nullopt) LogPrint(BCLog::NET, "Making network specific connection to %s on %s.\n", addrConnect.ToStringAddrPort(), GetNetworkName(preferred_net.value()));

            // Record addrman failure attempts when node has at least 2 persistent outbound connections to peers with
            // different netgroups in ipv4/ipv6 networks + all peers in Tor/I2P/CJDNS networks.
            // Don't record addrman failure attempts when node is offline. This can be identified since all local
            // network connections (if any) belong in the same netgroup, and the size of `outbound_ipv46_peer_netgroups` would only be 1.
            const bool count_failures{((int)outbound_ipv46_peer_netgroups.size() + outbound_privacy_network_peers) >= std::min(m_max_automatic_connections - 1, 2)};
            // Use BIP324 transport when both us and them have NODE_V2_P2P set.
            const bool use_v2transport(addrConnect.nServices & GetLocalServices() & NODE_P2P_V2);
            OpenNetworkConnection(addrConnect, count_failures, std::move(grant), /*strDest=*/nullptr, conn_type, use_v2transport);
        }
    }
}

std::vector<CAddress> CConnman::GetCurrentBlockRelayOnlyConns() const
{
    std::vector<CAddress> ret;
    LOCK(m_nodes_mutex);
    for (const CNode* pnode : m_nodes) {
        if (pnode->IsBlockOnlyConn()) {
            ret.push_back(pnode->addr);
        }
    }

    return ret;
}

std::vector<AddedNodeInfo> CConnman::GetAddedNodeInfo(bool include_connected) const
{
    std::vector<AddedNodeInfo> ret;

    std::list<AddedNodeParams> lAddresses(0);
    {
        LOCK(m_added_nodes_mutex);
        ret.reserve(m_added_node_params.size());
        std::copy(m_added_node_params.cbegin(), m_added_node_params.cend(), std::back_inserter(lAddresses));
    }


    // Build a map of all already connected addresses (by IP:port and by name) to inbound/outbound and resolved CService
    std::map<CService, bool> mapConnected;
    std::map<std::string, std::pair<bool, CService>> mapConnectedByName;
    {
        LOCK(m_nodes_mutex);
        for (const CNode* pnode : m_nodes) {
            if (pnode->addr.IsValid()) {
                mapConnected[pnode->addr] = pnode->IsInboundConn();
            }
            std::string addrName{pnode->m_addr_name};
            if (!addrName.empty()) {
                mapConnectedByName[std::move(addrName)] = std::make_pair(pnode->IsInboundConn(), static_cast<const CService&>(pnode->addr));
            }
        }
    }

    for (const auto& addr : lAddresses) {
        CService service{MaybeFlipIPv6toCJDNS(LookupNumeric(addr.m_added_node, GetDefaultPort(addr.m_added_node)))};
        AddedNodeInfo addedNode{addr, CService(), false, false};
        if (service.IsValid()) {
            // strAddNode is an IP:port
            auto it = mapConnected.find(service);
            if (it != mapConnected.end()) {
                if (!include_connected) {
                    continue;
                }
                addedNode.resolvedAddress = service;
                addedNode.fConnected = true;
                addedNode.fInbound = it->second;
            }
        } else {
            // strAddNode is a name
            auto it = mapConnectedByName.find(addr.m_added_node);
            if (it != mapConnectedByName.end()) {
                if (!include_connected) {
                    continue;
                }
                addedNode.resolvedAddress = it->second.second;
                addedNode.fConnected = true;
                addedNode.fInbound = it->second.first;
            }
        }
        ret.emplace_back(std::move(addedNode));
    }

    return ret;
}

void CConnman::ThreadOpenAddedConnections()
{
    AssertLockNotHeld(m_unused_i2p_sessions_mutex);
    AssertLockNotHeld(m_reconnections_mutex);
    while (true)
    {
        CSemaphoreGrant grant(*semAddnode);
        std::vector<AddedNodeInfo> vInfo = GetAddedNodeInfo(/*include_connected=*/false);
        bool tried = false;
        for (const AddedNodeInfo& info : vInfo) {
            if (!grant) {
                // If we've used up our semaphore and need a new one, let's not wait here since while we are waiting
                // the addednodeinfo state might change.
                break;
            }
            tried = true;
            CAddress addr(CService(), NODE_NONE);
            OpenNetworkConnection(addr, false, std::move(grant), info.m_params.m_added_node.c_str(), ConnectionType::MANUAL, info.m_params.m_use_v2transport);
            if (!interruptNet.sleep_for(std::chrono::milliseconds(500))) return;
            grant = CSemaphoreGrant(*semAddnode, /*fTry=*/true);
        }
        // See if any reconnections are desired.
        PerformReconnections();
        // Retry every 60 seconds if a connection was attempted, otherwise two seconds
        if (!interruptNet.sleep_for(std::chrono::seconds(tried ? 60 : 2)))
            return;
    }
}

// if successful, this moves the passed grant to the constructed node
void CConnman::OpenNetworkConnection(const CAddress& addrConnect, bool fCountFailure, CSemaphoreGrant&& grant_outbound, const char *pszDest, ConnectionType conn_type, bool use_v2transport)
{
    AssertLockNotHeld(m_unused_i2p_sessions_mutex);
    assert(conn_type != ConnectionType::INBOUND);

    //
    // Initiate outbound network connection
    //
    if (interruptNet) {
        return;
    }
    if (!fNetworkActive) {
        return;
    }
    if (!pszDest) {
        bool banned_or_discouraged = m_banman && (m_banman->IsDiscouraged(addrConnect) || m_banman->IsBanned(addrConnect));
        if (IsLocal(addrConnect) || banned_or_discouraged || AlreadyConnectedToAddress(addrConnect)) {
            return;
        }
    } else if (FindNode(std::string(pszDest)))
        return;

    CNode* pnode = ConnectNode(addrConnect, pszDest, fCountFailure, conn_type, use_v2transport);

    if (!pnode)
        return;
    pnode->grantOutbound = std::move(grant_outbound);

    m_msgproc->InitializeNode(*pnode, nLocalServices);
    {
        LOCK(m_nodes_mutex);
        m_nodes.push_back(pnode);

        // update connection count by network
        if (pnode->IsManualOrFullOutboundConn()) ++m_network_conn_counts[pnode->addr.GetNetwork()];
    }
}

Mutex NetEventsInterface::g_msgproc_mutex;

void CConnman::ThreadMessageHandler()
{
    LOCK(NetEventsInterface::g_msgproc_mutex);

    while (!flagInterruptMsgProc)
    {
        bool fMoreWork = false;

        {
            // Randomize the order in which we process messages from/to our peers.
            // This prevents attacks in which an attacker exploits having multiple
            // consecutive connections in the m_nodes list.
            const NodesSnapshot snap{*this, /*shuffle=*/true};

            for (CNode* pnode : snap.Nodes()) {
                if (pnode->fDisconnect)
                    continue;

                // Receive messages
                bool fMoreNodeWork = m_msgproc->ProcessMessages(pnode, flagInterruptMsgProc);
                fMoreWork |= (fMoreNodeWork && !pnode->fPauseSend);
                if (flagInterruptMsgProc)
                    return;
                // Send messages
                m_msgproc->SendMessages(pnode);

                if (flagInterruptMsgProc)
                    return;
            }
        }

        WAIT_LOCK(mutexMsgProc, lock);
        if (!fMoreWork) {
            condMsgProc.wait_until(lock, std::chrono::steady_clock::now() + std::chrono::milliseconds(100), [this]() EXCLUSIVE_LOCKS_REQUIRED(mutexMsgProc) { return fMsgProcWake; });
        }
        fMsgProcWake = false;
    }
}

void CConnman::ThreadI2PAcceptIncoming()
{
    static constexpr auto err_wait_begin = 1s;
    static constexpr auto err_wait_cap = 5min;
    auto err_wait = err_wait_begin;

    bool advertising_listen_addr = false;
    i2p::Connection conn;

    auto SleepOnFailure = [&]() {
        interruptNet.sleep_for(err_wait);
        if (err_wait < err_wait_cap) {
            err_wait += 1s;
        }
    };

    while (!interruptNet) {

        if (!m_i2p_sam_session->Listen(conn)) {
            if (advertising_listen_addr && conn.me.IsValid()) {
                RemoveLocal(conn.me);
                advertising_listen_addr = false;
            }
            SleepOnFailure();
            continue;
        }

        if (!advertising_listen_addr) {
            AddLocal(conn.me, LOCAL_MANUAL);
            advertising_listen_addr = true;
        }

        if (!m_i2p_sam_session->Accept(conn)) {
            SleepOnFailure();
            continue;
        }

        CreateNodeFromAcceptedSocket(std::move(conn.sock), NetPermissionFlags::None,
                                     CAddress{conn.me, NODE_NONE}, CAddress{conn.peer, NODE_NONE});

        err_wait = err_wait_begin;
    }
}

bool CConnman::BindListenPort(const CService& addrBind, bilingual_str& strError, NetPermissionFlags permissions)
{
    int nOne = 1;

    // Create socket for listening for incoming connections
    struct sockaddr_storage sockaddr;
    socklen_t len = sizeof(sockaddr);
    if (!addrBind.GetSockAddr((struct sockaddr*)&sockaddr, &len))
    {
        strError = strprintf(Untranslated("Bind address family for %s not supported"), addrBind.ToStringAddrPort());
        LogPrintLevel(BCLog::NET, BCLog::Level::Error, "%s\n", strError.original);
        return false;
    }

    std::unique_ptr<Sock> sock = CreateSock(addrBind.GetSAFamily(), SOCK_STREAM, IPPROTO_TCP);
    if (!sock) {
        strError = strprintf(Untranslated("Couldn't open socket for incoming connections (socket returned error %s)"), NetworkErrorString(WSAGetLastError()));
        LogPrintLevel(BCLog::NET, BCLog::Level::Error, "%s\n", strError.original);
        return false;
    }

    // Allow binding if the port is still in TIME_WAIT state after
    // the program was closed and restarted.
    if (sock->SetSockOpt(SOL_SOCKET, SO_REUSEADDR, (sockopt_arg_type)&nOne, sizeof(int)) == SOCKET_ERROR) {
        strError = strprintf(Untranslated("Error setting SO_REUSEADDR on socket: %s, continuing anyway"), NetworkErrorString(WSAGetLastError()));
        LogPrintf("%s\n", strError.original);
    }

    // some systems don't have IPV6_V6ONLY but are always v6only; others do have the option
    // and enable it by default or not. Try to enable it, if possible.
    if (addrBind.IsIPv6()) {
#ifdef IPV6_V6ONLY
        if (sock->SetSockOpt(IPPROTO_IPV6, IPV6_V6ONLY, (sockopt_arg_type)&nOne, sizeof(int)) == SOCKET_ERROR) {
            strError = strprintf(Untranslated("Error setting IPV6_V6ONLY on socket: %s, continuing anyway"), NetworkErrorString(WSAGetLastError()));
            LogPrintf("%s\n", strError.original);
        }
#endif
#ifdef WIN32
        int nProtLevel = PROTECTION_LEVEL_UNRESTRICTED;
        if (sock->SetSockOpt(IPPROTO_IPV6, IPV6_PROTECTION_LEVEL, (const char*)&nProtLevel, sizeof(int)) == SOCKET_ERROR) {
            strError = strprintf(Untranslated("Error setting IPV6_PROTECTION_LEVEL on socket: %s, continuing anyway"), NetworkErrorString(WSAGetLastError()));
            LogPrintf("%s\n", strError.original);
        }
#endif
    }

    if (sock->Bind(reinterpret_cast<struct sockaddr*>(&sockaddr), len) == SOCKET_ERROR) {
        int nErr = WSAGetLastError();
        if (nErr == WSAEADDRINUSE)
            strError = strprintf(_("Unable to bind to %s on this computer. %s is probably already running."), addrBind.ToStringAddrPort(), PACKAGE_NAME);
        else
            strError = strprintf(_("Unable to bind to %s on this computer (bind returned error %s)"), addrBind.ToStringAddrPort(), NetworkErrorString(nErr));
        LogPrintLevel(BCLog::NET, BCLog::Level::Error, "%s\n", strError.original);
        return false;
    }
    LogPrintf("Bound to %s\n", addrBind.ToStringAddrPort());

    // Listen for incoming connections
    if (sock->Listen(SOMAXCONN) == SOCKET_ERROR)
    {
        strError = strprintf(_("Listening for incoming connections failed (listen returned error %s)"), NetworkErrorString(WSAGetLastError()));
        LogPrintLevel(BCLog::NET, BCLog::Level::Error, "%s\n", strError.original);
        return false;
    }

    vhListenSocket.emplace_back(std::move(sock), permissions);
    return true;
}

void Discover()
{
    if (!fDiscover)
        return;

#ifdef WIN32
    // Get local host IP
    char pszHostName[256] = "";
    if (gethostname(pszHostName, sizeof(pszHostName)) != SOCKET_ERROR)
    {
        const std::vector<CNetAddr> addresses{LookupHost(pszHostName, 0, true)};
        for (const CNetAddr& addr : addresses)
        {
            if (AddLocal(addr, LOCAL_IF))
                LogPrintf("%s: %s - %s\n", __func__, pszHostName, addr.ToStringAddr());
        }
    }
#elif (HAVE_DECL_GETIFADDRS && HAVE_DECL_FREEIFADDRS)
    // Get local host ip
    struct ifaddrs* myaddrs;
    if (getifaddrs(&myaddrs) == 0)
    {
        for (struct ifaddrs* ifa = myaddrs; ifa != nullptr; ifa = ifa->ifa_next)
        {
            if (ifa->ifa_addr == nullptr) continue;
            if ((ifa->ifa_flags & IFF_UP) == 0) continue;
            if ((ifa->ifa_flags & IFF_LOOPBACK) != 0) continue;
            if (ifa->ifa_addr->sa_family == AF_INET)
            {
                struct sockaddr_in* s4 = (struct sockaddr_in*)(ifa->ifa_addr);
                CNetAddr addr(s4->sin_addr);
                if (AddLocal(addr, LOCAL_IF))
                    LogPrintf("%s: IPv4 %s: %s\n", __func__, ifa->ifa_name, addr.ToStringAddr());
            }
            else if (ifa->ifa_addr->sa_family == AF_INET6)
            {
                struct sockaddr_in6* s6 = (struct sockaddr_in6*)(ifa->ifa_addr);
                CNetAddr addr(s6->sin6_addr);
                if (AddLocal(addr, LOCAL_IF))
                    LogPrintf("%s: IPv6 %s: %s\n", __func__, ifa->ifa_name, addr.ToStringAddr());
            }
        }
        freeifaddrs(myaddrs);
    }
#endif
}

void CConnman::SetNetworkActive(bool active)
{
    LogPrintf("%s: %s\n", __func__, active);

    if (fNetworkActive == active) {
        return;
    }

    fNetworkActive = active;

    if (m_client_interface) {
        m_client_interface->NotifyNetworkActiveChanged(fNetworkActive);
    }
}

CConnman::CConnman(uint64_t nSeed0In, uint64_t nSeed1In, AddrMan& addrman_in,
                   const NetGroupManager& netgroupman, const CChainParams& params, bool network_active)
    : addrman(addrman_in)
    , m_netgroupman{netgroupman}
    , nSeed0(nSeed0In)
    , nSeed1(nSeed1In)
    , m_params(params)
{
    SetTryNewOutboundPeer(false);

    Options connOptions;
    Init(connOptions);
    SetNetworkActive(network_active);
}

NodeId CConnman::GetNewNodeId()
{
    return nLastNodeId.fetch_add(1, std::memory_order_relaxed);
}

uint16_t CConnman::GetDefaultPort(Network net) const
{
    return net == NET_I2P ? I2P_SAM31_PORT : m_params.GetDefaultPort();
}

uint16_t CConnman::GetDefaultPort(const std::string& addr) const
{
    CNetAddr a;
    return a.SetSpecial(addr) ? GetDefaultPort(a.GetNetwork()) : m_params.GetDefaultPort();
}

bool CConnman::Bind(const CService& addr_, unsigned int flags, NetPermissionFlags permissions)
{
    const CService addr{MaybeFlipIPv6toCJDNS(addr_)};

    bilingual_str strError;
    if (!BindListenPort(addr, strError, permissions)) {
        if ((flags & BF_REPORT_ERROR) && m_client_interface) {
            m_client_interface->ThreadSafeMessageBox(strError, "", CClientUIInterface::MSG_ERROR);
        }
        return false;
    }

    if (addr.IsRoutable() && fDiscover && !(flags & BF_DONT_ADVERTISE) && !NetPermissions::HasFlag(permissions, NetPermissionFlags::NoBan)) {
        AddLocal(addr, LOCAL_BIND);
    }

    return true;
}

bool CConnman::InitBinds(const Options& options)
{
    for (const auto& addrBind : options.vBinds) {
        if (!Bind(addrBind, BF_REPORT_ERROR, NetPermissionFlags::None)) {
            return false;
        }
    }
    for (const auto& addrBind : options.vWhiteBinds) {
        if (!Bind(addrBind.m_service, BF_REPORT_ERROR, addrBind.m_flags)) {
            return false;
        }
    }
    for (const auto& addr_bind : options.onion_binds) {
        if (!Bind(addr_bind, BF_REPORT_ERROR | BF_DONT_ADVERTISE, NetPermissionFlags::None)) {
            return false;
        }
    }
    if (options.bind_on_any) {
        // Don't consider errors to bind on IPv6 "::" fatal because the host OS
        // may not have IPv6 support and the user did not explicitly ask us to
        // bind on that.
        const CService ipv6_any{in6_addr(IN6ADDR_ANY_INIT), GetListenPort()}; // ::
        Bind(ipv6_any, BF_NONE, NetPermissionFlags::None);

        struct in_addr inaddr_any;
        inaddr_any.s_addr = htonl(INADDR_ANY);
        const CService ipv4_any{inaddr_any, GetListenPort()}; // 0.0.0.0
        if (!Bind(ipv4_any, BF_REPORT_ERROR, NetPermissionFlags::None)) {
            return false;
        }
    }
    return true;
}

bool CConnman::Start(CScheduler& scheduler, const Options& connOptions)
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);
    Init(connOptions);

    if (fListen && !InitBinds(connOptions)) {
        if (m_client_interface) {
            m_client_interface->ThreadSafeMessageBox(
                _("Failed to listen on any port. Use -listen=0 if you want this."),
                "", CClientUIInterface::MSG_ERROR);
        }
        return false;
    }

    Proxy i2p_sam;
    if (GetProxy(NET_I2P, i2p_sam) && connOptions.m_i2p_accept_incoming) {
        m_i2p_sam_session = std::make_unique<i2p::sam::Session>(gArgs.GetDataDirNet() / "i2p_private_key",
                                                                i2p_sam, &interruptNet);
    }

    for (const auto& strDest : connOptions.vSeedNodes) {
        AddAddrFetch(strDest);
    }

    if (m_use_addrman_outgoing) {
        // Load addresses from anchors.dat
        m_anchors = ReadAnchors(gArgs.GetDataDirNet() / ANCHORS_DATABASE_FILENAME);
        if (m_anchors.size() > MAX_BLOCK_RELAY_ONLY_ANCHORS) {
            m_anchors.resize(MAX_BLOCK_RELAY_ONLY_ANCHORS);
        }
        LogPrintf("%i block-relay-only anchors will be tried for connections.\n", m_anchors.size());
    }

    if (m_client_interface) {
        m_client_interface->InitMessage(_("Starting network threads…").translated);
    }

    fAddressesInitialized = true;

    if (semOutbound == nullptr) {
        // initialize semaphore
        semOutbound = std::make_unique<CSemaphore>(std::min(m_max_automatic_outbound, m_max_automatic_connections));
    }
    if (semAddnode == nullptr) {
        // initialize semaphore
        semAddnode = std::make_unique<CSemaphore>(m_max_addnode);
    }

    //
    // Start threads
    //
    assert(m_msgproc);
    interruptNet.reset();
    flagInterruptMsgProc = false;

    {
        LOCK(mutexMsgProc);
        fMsgProcWake = false;
    }

    // Send and receive from sockets, accept connections
    threadSocketHandler = std::thread(&util::TraceThread, "net", [this] { ThreadSocketHandler(); });

    if (!gArgs.GetBoolArg("-dnsseed", DEFAULT_DNSSEED))
        LogPrintf("DNS seeding disabled\n");
    else
        threadDNSAddressSeed = std::thread(&util::TraceThread, "dnsseed", [this] { ThreadDNSAddressSeed(); });

    // Initiate manual connections
    threadOpenAddedConnections = std::thread(&util::TraceThread, "addcon", [this] { ThreadOpenAddedConnections(); });

    if (connOptions.m_use_addrman_outgoing && !connOptions.m_specified_outgoing.empty()) {
        if (m_client_interface) {
            m_client_interface->ThreadSafeMessageBox(
                _("Cannot provide specific connections and have addrman find outgoing connections at the same time."),
                "", CClientUIInterface::MSG_ERROR);
        }
        return false;
    }
    if (connOptions.m_use_addrman_outgoing || !connOptions.m_specified_outgoing.empty()) {
        threadOpenConnections = std::thread(
            &util::TraceThread, "opencon",
            [this, connect = connOptions.m_specified_outgoing] { ThreadOpenConnections(connect); });
    }

    // Process messages
    threadMessageHandler = std::thread(&util::TraceThread, "msghand", [this] { ThreadMessageHandler(); });

    if (m_i2p_sam_session) {
        threadI2PAcceptIncoming =
            std::thread(&util::TraceThread, "i2paccept", [this] { ThreadI2PAcceptIncoming(); });
    }

    // Dump network addresses
    scheduler.scheduleEvery([this] { DumpAddresses(); }, DUMP_PEERS_INTERVAL);

    // Run the ASMap Health check once and then schedule it to run every 24h.
    if (m_netgroupman.UsingASMap()) {
        ASMapHealthCheck();
        scheduler.scheduleEvery([this] { ASMapHealthCheck(); }, ASMAP_HEALTH_CHECK_INTERVAL);
    }

    return true;
}

class CNetCleanup
{
public:
    CNetCleanup() = default;

    ~CNetCleanup()
    {
#ifdef WIN32
        // Shutdown Windows Sockets
        WSACleanup();
#endif
    }
};
static CNetCleanup instance_of_cnetcleanup;

void CConnman::Interrupt()
{
    {
        LOCK(mutexMsgProc);
        flagInterruptMsgProc = true;
    }
    condMsgProc.notify_all();

    interruptNet();
    g_socks5_interrupt();

    if (semOutbound) {
        for (int i=0; i<m_max_automatic_outbound; i++) {
            semOutbound->post();
        }
    }

    if (semAddnode) {
        for (int i=0; i<m_max_addnode; i++) {
            semAddnode->post();
        }
    }
}

void CConnman::StopThreads()
{
    if (threadI2PAcceptIncoming.joinable()) {
        threadI2PAcceptIncoming.join();
    }
    if (threadMessageHandler.joinable())
        threadMessageHandler.join();
    if (threadOpenConnections.joinable())
        threadOpenConnections.join();
    if (threadOpenAddedConnections.joinable())
        threadOpenAddedConnections.join();
    if (threadDNSAddressSeed.joinable())
        threadDNSAddressSeed.join();
    if (threadSocketHandler.joinable())
        threadSocketHandler.join();
}

void CConnman::StopNodes()
{
    if (fAddressesInitialized) {
        DumpAddresses();
        fAddressesInitialized = false;

        if (m_use_addrman_outgoing) {
            // Anchor connections are only dumped during clean shutdown.
            std::vector<CAddress> anchors_to_dump = GetCurrentBlockRelayOnlyConns();
            if (anchors_to_dump.size() > MAX_BLOCK_RELAY_ONLY_ANCHORS) {
                anchors_to_dump.resize(MAX_BLOCK_RELAY_ONLY_ANCHORS);
            }
            DumpAnchors(gArgs.GetDataDirNet() / ANCHORS_DATABASE_FILENAME, anchors_to_dump);
        }
    }

    // Delete peer connections.
    std::vector<CNode*> nodes;
    WITH_LOCK(m_nodes_mutex, nodes.swap(m_nodes));
    for (CNode* pnode : nodes) {
        pnode->CloseSocketDisconnect();
        DeleteNode(pnode);
    }

    for (CNode* pnode : m_nodes_disconnected) {
        DeleteNode(pnode);
    }
    m_nodes_disconnected.clear();
    vhListenSocket.clear();
    semOutbound.reset();
    semAddnode.reset();
}

void CConnman::DeleteNode(CNode* pnode)
{
    assert(pnode);
    m_msgproc->FinalizeNode(*pnode);
    delete pnode;
}

CConnman::~CConnman()
{
    Interrupt();
    Stop();
}

std::vector<CAddress> CConnman::GetAddresses(size_t max_addresses, size_t max_pct, std::optional<Network> network, const bool filtered) const
{
    std::vector<CAddress> addresses = addrman.GetAddr(max_addresses, max_pct, network, filtered);
    if (m_banman) {
        addresses.erase(std::remove_if(addresses.begin(), addresses.end(),
                        [this](const CAddress& addr){return m_banman->IsDiscouraged(addr) || m_banman->IsBanned(addr);}),
                        addresses.end());
    }
    return addresses;
}

std::vector<CAddress> CConnman::GetAddresses(CNode& requestor, size_t max_addresses, size_t max_pct)
{
    auto local_socket_bytes = requestor.addrBind.GetAddrBytes();
    uint64_t cache_id = GetDeterministicRandomizer(RANDOMIZER_ID_ADDRCACHE)
        .Write(requestor.ConnectedThroughNetwork())
        .Write(local_socket_bytes)
        // For outbound connections, the port of the bound address is randomly
        // assigned by the OS and would therefore not be useful for seeding.
        .Write(requestor.IsInboundConn() ? requestor.addrBind.GetPort() : 0)
        .Finalize();
    const auto current_time = GetTime<std::chrono::microseconds>();
    auto r = m_addr_response_caches.emplace(cache_id, CachedAddrResponse{});
    CachedAddrResponse& cache_entry = r.first->second;
    if (cache_entry.m_cache_entry_expiration < current_time) { // If emplace() added new one it has expiration 0.
        cache_entry.m_addrs_response_cache = GetAddresses(max_addresses, max_pct, /*network=*/std::nullopt);
        // Choosing a proper cache lifetime is a trade-off between the privacy leak minimization
        // and the usefulness of ADDR responses to honest users.
        //
        // Longer cache lifetime makes it more difficult for an attacker to scrape
        // enough AddrMan data to maliciously infer something useful.
        // By the time an attacker scraped enough AddrMan records, most of
        // the records should be old enough to not leak topology info by
        // e.g. analyzing real-time changes in timestamps.
        //
        // It takes only several hundred requests to scrape everything from an AddrMan containing 100,000 nodes,
        // so ~24 hours of cache lifetime indeed makes the data less inferable by the time
        // most of it could be scraped (considering that timestamps are updated via
        // ADDR self-announcements and when nodes communicate).
        // We also should be robust to those attacks which may not require scraping *full* victim's AddrMan
        // (because even several timestamps of the same handful of nodes may leak privacy).
        //
        // On the other hand, longer cache lifetime makes ADDR responses
        // outdated and less useful for an honest requestor, e.g. if most nodes
        // in the ADDR response are no longer active.
        //
        // However, the churn in the network is known to be rather low. Since we consider
        // nodes to be "terrible" (see IsTerrible()) if the timestamps are older than 30 days,
        // max. 24 hours of "penalty" due to cache shouldn't make any meaningful difference
        // in terms of the freshness of the response.
        cache_entry.m_cache_entry_expiration = current_time +
            21h + FastRandomContext().randrange<std::chrono::microseconds>(6h);
    }
    return cache_entry.m_addrs_response_cache;
}

bool CConnman::AddNode(const AddedNodeParams& add)
{
    const CService resolved(LookupNumeric(add.m_added_node, GetDefaultPort(add.m_added_node)));
    const bool resolved_is_valid{resolved.IsValid()};

    LOCK(m_added_nodes_mutex);
    for (const auto& it : m_added_node_params) {
        if (add.m_added_node == it.m_added_node || (resolved_is_valid && resolved == LookupNumeric(it.m_added_node, GetDefaultPort(it.m_added_node)))) return false;
    }

    m_added_node_params.push_back(add);
    return true;
}

bool CConnman::RemoveAddedNode(const std::string& strNode)
{
    LOCK(m_added_nodes_mutex);
    for (auto it = m_added_node_params.begin(); it != m_added_node_params.end(); ++it) {
        if (strNode == it->m_added_node) {
            m_added_node_params.erase(it);
            return true;
        }
    }
    return false;
}

bool CConnman::AddedNodesContain(const CAddress& addr) const
{
    AssertLockNotHeld(m_added_nodes_mutex);
    const std::string addr_str{addr.ToStringAddr()};
    const std::string addr_port_str{addr.ToStringAddrPort()};
    LOCK(m_added_nodes_mutex);
    return (m_added_node_params.size() < 24 // bound the query to a reasonable limit
            && std::any_of(m_added_node_params.cbegin(), m_added_node_params.cend(),
                           [&](const auto& p) { return p.m_added_node == addr_str || p.m_added_node == addr_port_str; }));
}

size_t CConnman::GetNodeCount(ConnectionDirection flags) const
{
    LOCK(m_nodes_mutex);
    if (flags == ConnectionDirection::Both) // Shortcut if we want total
        return m_nodes.size();

    int nNum = 0;
    for (const auto& pnode : m_nodes) {
        if (flags & (pnode->IsInboundConn() ? ConnectionDirection::In : ConnectionDirection::Out)) {
            nNum++;
        }
    }

    return nNum;
}


std::map<CNetAddr, LocalServiceInfo> CConnman::getNetLocalAddresses() const
{
    LOCK(g_maplocalhost_mutex);
    return mapLocalHost;
}

uint32_t CConnman::GetMappedAS(const CNetAddr& addr) const
{
    return m_netgroupman.GetMappedAS(addr);
}

void CConnman::GetNodeStats(std::vector<CNodeStats>& vstats) const
{
    vstats.clear();
    LOCK(m_nodes_mutex);
    vstats.reserve(m_nodes.size());
    for (CNode* pnode : m_nodes) {
        vstats.emplace_back();
        pnode->CopyStats(vstats.back());
        vstats.back().m_mapped_as = GetMappedAS(pnode->addr);
    }
}

bool CConnman::DisconnectNode(const std::string& strNode)
{
    LOCK(m_nodes_mutex);
    if (CNode* pnode = FindNode(strNode)) {
        LogPrint(BCLog::NET, "disconnect by address%s matched peer=%d; disconnecting\n", (fLogIPs ? strprintf("=%s", strNode) : ""), pnode->GetId());
        pnode->fDisconnect = true;
        return true;
    }
    return false;
}

bool CConnman::DisconnectNode(const CSubNet& subnet)
{
    bool disconnected = false;
    LOCK(m_nodes_mutex);
    for (CNode* pnode : m_nodes) {
        if (subnet.Match(pnode->addr)) {
            LogPrint(BCLog::NET, "disconnect by subnet%s matched peer=%d; disconnecting\n", (fLogIPs ? strprintf("=%s", subnet.ToString()) : ""), pnode->GetId());
            pnode->fDisconnect = true;
            disconnected = true;
        }
    }
    return disconnected;
}

bool CConnman::DisconnectNode(const CNetAddr& addr)
{
    return DisconnectNode(CSubNet(addr));
}

bool CConnman::DisconnectNode(NodeId id)
{
    LOCK(m_nodes_mutex);
    for(CNode* pnode : m_nodes) {
        if (id == pnode->GetId()) {
            LogPrint(BCLog::NET, "disconnect by id peer=%d; disconnecting\n", pnode->GetId());
            pnode->fDisconnect = true;
            return true;
        }
    }
    return false;
}

void CConnman::RecordBytesRecv(uint64_t bytes)
{
    nTotalBytesRecv += bytes;
}

void CConnman::RecordBytesSent(uint64_t bytes)
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);
    LOCK(m_total_bytes_sent_mutex);

    nTotalBytesSent += bytes;

    const auto now = GetTime<std::chrono::seconds>();
    if (nMaxOutboundCycleStartTime + MAX_UPLOAD_TIMEFRAME < now)
    {
        // timeframe expired, reset cycle
        nMaxOutboundCycleStartTime = now;
        nMaxOutboundTotalBytesSentInCycle = 0;
    }

    nMaxOutboundTotalBytesSentInCycle += bytes;
}

uint64_t CConnman::GetMaxOutboundTarget() const
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);
    LOCK(m_total_bytes_sent_mutex);
    return nMaxOutboundLimit;
}

std::chrono::seconds CConnman::GetMaxOutboundTimeframe() const
{
    return MAX_UPLOAD_TIMEFRAME;
}

std::chrono::seconds CConnman::GetMaxOutboundTimeLeftInCycle() const
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);
    LOCK(m_total_bytes_sent_mutex);
    return GetMaxOutboundTimeLeftInCycle_();
}

std::chrono::seconds CConnman::GetMaxOutboundTimeLeftInCycle_() const
{
    AssertLockHeld(m_total_bytes_sent_mutex);

    if (nMaxOutboundLimit == 0)
        return 0s;

    if (nMaxOutboundCycleStartTime.count() == 0)
        return MAX_UPLOAD_TIMEFRAME;

    const std::chrono::seconds cycleEndTime = nMaxOutboundCycleStartTime + MAX_UPLOAD_TIMEFRAME;
    const auto now = GetTime<std::chrono::seconds>();
    return (cycleEndTime < now) ? 0s : cycleEndTime - now;
}

bool CConnman::OutboundTargetReached(bool historicalBlockServingLimit) const
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);
    LOCK(m_total_bytes_sent_mutex);
    if (nMaxOutboundLimit == 0)
        return false;

    if (historicalBlockServingLimit)
    {
        // keep a large enough buffer to at least relay each block once
        const std::chrono::seconds timeLeftInCycle = GetMaxOutboundTimeLeftInCycle_();
        const uint64_t buffer = timeLeftInCycle / std::chrono::minutes{10} * MAX_BLOCK_SERIALIZED_SIZE;
        if (buffer >= nMaxOutboundLimit || nMaxOutboundTotalBytesSentInCycle >= nMaxOutboundLimit - buffer)
            return true;
    }
    else if (nMaxOutboundTotalBytesSentInCycle >= nMaxOutboundLimit)
        return true;

    return false;
}

uint64_t CConnman::GetOutboundTargetBytesLeft() const
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);
    LOCK(m_total_bytes_sent_mutex);
    if (nMaxOutboundLimit == 0)
        return 0;

    return (nMaxOutboundTotalBytesSentInCycle >= nMaxOutboundLimit) ? 0 : nMaxOutboundLimit - nMaxOutboundTotalBytesSentInCycle;
}

uint64_t CConnman::GetTotalBytesRecv() const
{
    return nTotalBytesRecv;
}

uint64_t CConnman::GetTotalBytesSent() const
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);
    LOCK(m_total_bytes_sent_mutex);
    return nTotalBytesSent;
}

ServiceFlags CConnman::GetLocalServices() const
{
    return nLocalServices;
}

static std::unique_ptr<Transport> MakeTransport(NodeId id, bool use_v2transport, bool inbound) noexcept
{
    if (use_v2transport) {
        return std::make_unique<V2Transport>(id, /*initiating=*/!inbound);
    } else {
        return std::make_unique<V1Transport>(id);
    }
}

CNode::CNode(NodeId idIn,
             std::shared_ptr<Sock> sock,
             const CAddress& addrIn,
             uint64_t nKeyedNetGroupIn,
             uint64_t nLocalHostNonceIn,
             const CAddress& addrBindIn,
             const std::string& addrNameIn,
             ConnectionType conn_type_in,
             bool inbound_onion,
             CNodeOptions&& node_opts)
    : m_transport{MakeTransport(idIn, node_opts.use_v2transport, conn_type_in == ConnectionType::INBOUND)},
      m_permission_flags{node_opts.permission_flags},
      m_sock{sock},
      m_connected{GetTime<std::chrono::seconds>()},
      addr{addrIn},
      addrBind{addrBindIn},
      m_addr_name{addrNameIn.empty() ? addr.ToStringAddrPort() : addrNameIn},
      m_dest(addrNameIn),
      m_inbound_onion{inbound_onion},
      m_prefer_evict{node_opts.prefer_evict},
      nKeyedNetGroup{nKeyedNetGroupIn},
      m_conn_type{conn_type_in},
      id{idIn},
      nLocalHostNonce{nLocalHostNonceIn},
      m_recv_flood_size{node_opts.recv_flood_size},
      m_i2p_sam_session{std::move(node_opts.i2p_sam_session)}
{
    if (inbound_onion) assert(conn_type_in == ConnectionType::INBOUND);

    for (const auto& msg : ALL_NET_MESSAGE_TYPES) {
        mapRecvBytesPerMsgType[msg] = 0;
    }
    mapRecvBytesPerMsgType[NET_MESSAGE_TYPE_OTHER] = 0;

    if (fLogIPs) {
        LogPrint(BCLog::NET, "Added connection to %s peer=%d\n", m_addr_name, id);
    } else {
        LogPrint(BCLog::NET, "Added connection peer=%d\n", id);
    }
}

void CNode::MarkReceivedMsgsForProcessing()
{
    AssertLockNotHeld(m_msg_process_queue_mutex);

    size_t nSizeAdded = 0;
    for (const auto& msg : vRecvMsg) {
        // vRecvMsg contains only completed CNetMessage
        // the single possible partially deserialized message are held by TransportDeserializer
        nSizeAdded += msg.m_raw_message_size;
    }

    LOCK(m_msg_process_queue_mutex);
    m_msg_process_queue.splice(m_msg_process_queue.end(), vRecvMsg);
    m_msg_process_queue_size += nSizeAdded;
    fPauseRecv = m_msg_process_queue_size > m_recv_flood_size;
}

std::optional<std::pair<CNetMessage, bool>> CNode::PollMessage()
{
    LOCK(m_msg_process_queue_mutex);
    if (m_msg_process_queue.empty()) return std::nullopt;

    std::list<CNetMessage> msgs;
    // Just take one message
    msgs.splice(msgs.begin(), m_msg_process_queue, m_msg_process_queue.begin());
    m_msg_process_queue_size -= msgs.front().m_raw_message_size;
    fPauseRecv = m_msg_process_queue_size > m_recv_flood_size;

    return std::make_pair(std::move(msgs.front()), !m_msg_process_queue.empty());
}

bool CConnman::NodeFullyConnected(const CNode* pnode)
{
    return pnode && pnode->fSuccessfullyConnected && !pnode->fDisconnect;
}

void CConnman::PushMessage(CNode* pnode, CSerializedNetMsg&& msg)
{
    AssertLockNotHeld(m_total_bytes_sent_mutex);
    size_t nMessageSize = msg.data.size();
    LogPrint(BCLog::NET, "sending %s (%d bytes) peer=%d\n", msg.m_type, nMessageSize, pnode->GetId());
    if (gArgs.GetBoolArg("-capturemessages", false)) {
        CaptureMessage(pnode->addr, msg.m_type, msg.data, /*is_incoming=*/false);
    }

    TRACE6(net, outbound_message,
        pnode->GetId(),
        pnode->m_addr_name.c_str(),
        pnode->ConnectionTypeAsString().c_str(),
        msg.m_type.c_str(),
        msg.data.size(),
        msg.data.data()
    );

    size_t nBytesSent = 0;
    {
        LOCK(pnode->cs_vSend);
        // Check if the transport still has unsent bytes, and indicate to it that we're about to
        // give it a message to send.
        const auto& [to_send, more, _msg_type] =
            pnode->m_transport->GetBytesToSend(/*have_next_message=*/true);
        const bool queue_was_empty{to_send.empty() && pnode->vSendMsg.empty()};

        // Update memory usage of send buffer.
        pnode->m_send_memusage += msg.GetMemoryUsage();
        if (pnode->m_send_memusage + pnode->m_transport->GetSendMemoryUsage() > nSendBufferMaxSize) pnode->fPauseSend = true;
        // Move message to vSendMsg queue.
        pnode->vSendMsg.push_back(std::move(msg));

        // If there was nothing to send before, and there is now (predicted by the "more" value
        // returned by the GetBytesToSend call above), attempt "optimistic write":
        // because the poll/select loop may pause for SELECT_TIMEOUT_MILLISECONDS before actually
        // doing a send, try sending from the calling thread if the queue was empty before.
        // With a V1Transport, more will always be true here, because adding a message always
        // results in sendable bytes there, but with V2Transport this is not the case (it may
        // still be in the handshake).
        if (queue_was_empty && more) {
            std::tie(nBytesSent, std::ignore) = SocketSendData(*pnode);
        }
    }
    if (nBytesSent) RecordBytesSent(nBytesSent);
}

bool CConnman::ForNode(NodeId id, std::function<bool(CNode* pnode)> func)
{
    CNode* found = nullptr;
    LOCK(m_nodes_mutex);
    for (auto&& pnode : m_nodes) {
        if(pnode->GetId() == id) {
            found = pnode;
            break;
        }
    }
    return found != nullptr && NodeFullyConnected(found) && func(found);
}

CSipHasher CConnman::GetDeterministicRandomizer(uint64_t id) const
{
    return CSipHasher(nSeed0, nSeed1).Write(id);
}

uint64_t CConnman::CalculateKeyedNetGroup(const CAddress& address) const
{
    std::vector<unsigned char> vchNetGroup(m_netgroupman.GetGroup(address));

    return GetDeterministicRandomizer(RANDOMIZER_ID_NETGROUP).Write(vchNetGroup).Finalize();
}

void CConnman::PerformReconnections()
{
    AssertLockNotHeld(m_reconnections_mutex);
    AssertLockNotHeld(m_unused_i2p_sessions_mutex);
    while (true) {
        // Move first element of m_reconnections to todo (avoiding an allocation inside the lock).
        decltype(m_reconnections) todo;
        {
            LOCK(m_reconnections_mutex);
            if (m_reconnections.empty()) break;
            todo.splice(todo.end(), m_reconnections, m_reconnections.begin());
        }

        auto& item = *todo.begin();
        OpenNetworkConnection(item.addr_connect,
                              // We only reconnect if the first attempt to connect succeeded at
                              // connection time, but then failed after the CNode object was
                              // created. Since we already know connecting is possible, do not
                              // count failure to reconnect.
                              /*fCountFailure=*/false,
                              std::move(item.grant),
                              item.destination.empty() ? nullptr : item.destination.c_str(),
                              item.conn_type,
                              item.use_v2transport);
    }
}

void CConnman::ASMapHealthCheck()
{
    const std::vector<CAddress> v4_addrs{GetAddresses(/*max_addresses=*/ 0, /*max_pct=*/ 0, Network::NET_IPV4, /*filtered=*/ false)};
    const std::vector<CAddress> v6_addrs{GetAddresses(/*max_addresses=*/ 0, /*max_pct=*/ 0, Network::NET_IPV6, /*filtered=*/ false)};
    std::vector<CNetAddr> clearnet_addrs;
    clearnet_addrs.reserve(v4_addrs.size() + v6_addrs.size());
    std::transform(v4_addrs.begin(), v4_addrs.end(), std::back_inserter(clearnet_addrs),
        [](const CAddress& addr) { return static_cast<CNetAddr>(addr); });
    std::transform(v6_addrs.begin(), v6_addrs.end(), std::back_inserter(clearnet_addrs),
        [](const CAddress& addr) { return static_cast<CNetAddr>(addr); });
    m_netgroupman.ASMapHealthCheck(clearnet_addrs);
}

// Dump binary message to file, with timestamp.
static void CaptureMessageToFile(const CAddress& addr,
                                 const std::string& msg_type,
                                 Span<const unsigned char> data,
                                 bool is_incoming)
{
    // Note: This function captures the message at the time of processing,
    // not at socket receive/send time.
    // This ensures that the messages are always in order from an application
    // layer (processing) perspective.
    auto now = GetTime<std::chrono::microseconds>();

    // Windows folder names cannot include a colon
    std::string clean_addr = addr.ToStringAddrPort();
    std::replace(clean_addr.begin(), clean_addr.end(), ':', '_');

    fs::path base_path = gArgs.GetDataDirNet() / "message_capture" / fs::u8path(clean_addr);
    fs::create_directories(base_path);

    fs::path path = base_path / (is_incoming ? "msgs_recv.dat" : "msgs_sent.dat");
    AutoFile f{fsbridge::fopen(path, "ab")};

    ser_writedata64(f, now.count());
    f << Span{msg_type};
    for (auto i = msg_type.length(); i < CMessageHeader::COMMAND_SIZE; ++i) {
        f << uint8_t{'\0'};
    }
    uint32_t size = data.size();
    ser_writedata32(f, size);
    f << data;
}

std::function<void(const CAddress& addr,
                   const std::string& msg_type,
                   Span<const unsigned char> data,
                   bool is_incoming)>
    CaptureMessage = CaptureMessageToFile;