aboutsummaryrefslogtreecommitdiff
path: root/src/addrman.h
blob: 30b8ef1a30b3ecec41f150c62f6f627c13352f21 (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
// Copyright (c) 2012 Pieter Wuille
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef _BITCOIN_ADDRMAN
#define _BITCOIN_ADDRMAN 1

#include "netbase.h"
#include "protocol.h"
#include "util.h"
#include "sync.h"


#include <map>
#include <vector>

#include <openssl/rand.h>


/** Extended statistics about a CAddress */
class CAddrInfo : public CAddress
{
private:
    // where knowledge about this address first came from
    CNetAddr source;

    // last successful connection by us
    int64 nLastSuccess;

    // last try whatsoever by us:
    // int64 CAddress::nLastTry

    // connection attempts since last successful attempt
    int nAttempts;

    // reference count in new sets (memory only)
    int nRefCount;

    // in tried set? (memory only)
    bool fInTried;

    // position in vRandom
    int nRandomPos;

    friend class CAddrMan;

public:

    IMPLEMENT_SERIALIZE(
        CAddress* pthis = (CAddress*)(this);
        READWRITE(*pthis);
        READWRITE(source);
        READWRITE(nLastSuccess);
        READWRITE(nAttempts);
    )

    void Init()
    {
        nLastSuccess = 0;
        nLastTry = 0;
        nAttempts = 0;
        nRefCount = 0;
        fInTried = false;
        nRandomPos = -1;
    }

    CAddrInfo(const CAddress &addrIn, const CNetAddr &addrSource) : CAddress(addrIn), source(addrSource)
    {
        Init();
    }

    CAddrInfo() : CAddress(), source()
    {
        Init();
    }

    // Calculate in which "tried" bucket this entry belongs
    int GetTriedBucket(const std::vector<unsigned char> &nKey) const;

    // Calculate in which "new" bucket this entry belongs, given a certain source
    int GetNewBucket(const std::vector<unsigned char> &nKey, const CNetAddr& src) const;

    // Calculate in which "new" bucket this entry belongs, using its default source
    int GetNewBucket(const std::vector<unsigned char> &nKey) const
    {
        return GetNewBucket(nKey, source);
    }

    // Determine whether the statistics about this entry are bad enough so that it can just be deleted
    bool IsTerrible(int64 nNow = GetAdjustedTime()) const;

    // Calculate the relative chance this entry should be given when selecting nodes to connect to
    double GetChance(int64 nNow = GetAdjustedTime()) const;

};

// Stochastic address manager
//
// Design goals:
//  * Only keep a limited number of addresses around, so that addr.dat and memory requirements do not grow without bound.
//  * Keep the address tables in-memory, and asynchronously dump the entire to able in addr.dat.
//  * Make sure no (localized) attacker can fill the entire table with his nodes/addresses.
//
// To that end:
//  * Addresses are organized into buckets.
//    * Address that have not yet been tried go into 256 "new" buckets.
//      * Based on the address range (/16 for IPv4) of source of the information, 32 buckets are selected at random
//      * The actual bucket is chosen from one of these, based on the range the address itself is located.
//      * One single address can occur in up to 4 different buckets, to increase selection chances for addresses that
//        are seen frequently. The chance for increasing this multiplicity decreases exponentially.
//      * When adding a new address to a full bucket, a randomly chosen entry (with a bias favoring less recently seen
//        ones) is removed from it first.
//    * Addresses of nodes that are known to be accessible go into 64 "tried" buckets.
//      * Each address range selects at random 4 of these buckets.
//      * The actual bucket is chosen from one of these, based on the full address.
//      * When adding a new good address to a full bucket, a randomly chosen entry (with a bias favoring less recently
//        tried ones) is evicted from it, back to the "new" buckets.
//    * Bucket selection is based on cryptographic hashing, using a randomly-generated 256-bit key, which should not
//      be observable by adversaries.
//    * Several indexes are kept for high performance. Defining DEBUG_ADDRMAN will introduce frequent (and expensive)
//      consistency checks for the entire data structure.

// total number of buckets for tried addresses
#define ADDRMAN_TRIED_BUCKET_COUNT 64

// maximum allowed number of entries in buckets for tried addresses
#define ADDRMAN_TRIED_BUCKET_SIZE 64

// total number of buckets for new addresses
#define ADDRMAN_NEW_BUCKET_COUNT 256

// maximum allowed number of entries in buckets for new addresses
#define ADDRMAN_NEW_BUCKET_SIZE 64

// over how many buckets entries with tried addresses from a single group (/16 for IPv4) are spread
#define ADDRMAN_TRIED_BUCKETS_PER_GROUP 4

// over how many buckets entries with new addresses originating from a single group are spread
#define ADDRMAN_NEW_BUCKETS_PER_SOURCE_GROUP 32

// in how many buckets for entries with new addresses a single address may occur
#define ADDRMAN_NEW_BUCKETS_PER_ADDRESS 4

// how many entries in a bucket with tried addresses are inspected, when selecting one to replace
#define ADDRMAN_TRIED_ENTRIES_INSPECT_ON_EVICT 4

// how old addresses can maximally be
#define ADDRMAN_HORIZON_DAYS 30

// after how many failed attempts we give up on a new node
#define ADDRMAN_RETRIES 3

// how many successive failures are allowed ...
#define ADDRMAN_MAX_FAILURES 10

// ... in at least this many days
#define ADDRMAN_MIN_FAIL_DAYS 7

// the maximum percentage of nodes to return in a getaddr call
#define ADDRMAN_GETADDR_MAX_PCT 23

// the maximum number of nodes to return in a getaddr call
#define ADDRMAN_GETADDR_MAX 2500

/** Stochastical (IP) address manager */
class CAddrMan
{
private:
    // critical section to protect the inner data structures
    mutable CCriticalSection cs;

    // secret key to randomize bucket select with
    std::vector<unsigned char> nKey;

    // last used nId
    int nIdCount;

    // table with information about all nId's
    std::map<int, CAddrInfo> mapInfo;

    // find an nId based on its network address
    std::map<CNetAddr, int> mapAddr;

    // randomly-ordered vector of all nId's
    std::vector<int> vRandom;

    // number of "tried" entries
    int nTried;

    // list of "tried" buckets
    std::vector<std::vector<int> > vvTried;

    // number of (unique) "new" entries
    int nNew;

    // list of "new" buckets
    std::vector<std::set<int> > vvNew;

protected:

    // Find an entry.
    CAddrInfo* Find(const CNetAddr& addr, int *pnId = NULL);

    // find an entry, creating it if necessary.
    // nTime and nServices of found node is updated, if necessary.
    CAddrInfo* Create(const CAddress &addr, const CNetAddr &addrSource, int *pnId = NULL);

    // Swap two elements in vRandom.
    void SwapRandom(unsigned int nRandomPos1, unsigned int nRandomPos2);

    // Return position in given bucket to replace.
    int SelectTried(int nKBucket);

    // Remove an element from a "new" bucket.
    // This is the only place where actual deletes occur.
    // They are never deleted while in the "tried" table, only possibly evicted back to the "new" table.
    int ShrinkNew(int nUBucket);
 
    // Move an entry from the "new" table(s) to the "tried" table
    // @pre vvUnkown[nOrigin].count(nId) != 0
    void MakeTried(CAddrInfo& info, int nId, int nOrigin);

    // Mark an entry "good", possibly moving it from "new" to "tried".
    void Good_(const CService &addr, int64 nTime);

    // Add an entry to the "new" table.
    bool Add_(const CAddress &addr, const CNetAddr& source, int64 nTimePenalty);

    // Mark an entry as attempted to connect.
    void Attempt_(const CService &addr, int64 nTime);

    // Select an address to connect to.
    // nUnkBias determines how much to favor new addresses over tried ones (min=0, max=100)
    CAddress Select_(int nUnkBias);

#ifdef DEBUG_ADDRMAN
    // Perform consistency check. Returns an error code or zero.
    int Check_();
#endif

    // Select several addresses at once.
    void GetAddr_(std::vector<CAddress> &vAddr);

    // Mark an entry as currently-connected-to.
    void Connected_(const CService &addr, int64 nTime);

public:

    IMPLEMENT_SERIALIZE
    (({
        // serialized format:
        // * version byte (currently 0)
        // * nKey
        // * nNew
        // * nTried
        // * number of "new" buckets
        // * all nNew addrinfo's in vvNew
        // * all nTried addrinfo's in vvTried
        // * for each bucket:
        //   * number of elements
        //   * for each element: index
        //
        // Notice that vvTried, mapAddr and vVector are never encoded explicitly;
        // they are instead reconstructed from the other information.
        //
        // vvNew is serialized, but only used if ADDRMAN_UNKOWN_BUCKET_COUNT didn't change,
        // otherwise it is reconstructed as well.
        //
        // This format is more complex, but significantly smaller (at most 1.5 MiB), and supports
        // changes to the ADDRMAN_ parameters without breaking the on-disk structure.
        {
            LOCK(cs);
            unsigned char nVersion = 0;
            READWRITE(nVersion);
            READWRITE(nKey);
            READWRITE(nNew);
            READWRITE(nTried);

            CAddrMan *am = const_cast<CAddrMan*>(this);
            if (fWrite)
            {
                int nUBuckets = ADDRMAN_NEW_BUCKET_COUNT;
                READWRITE(nUBuckets);
                std::map<int, int> mapUnkIds;
                int nIds = 0;
                for (std::map<int, CAddrInfo>::iterator it = am->mapInfo.begin(); it != am->mapInfo.end(); it++)
                {
                    if (nIds == nNew) break; // this means nNew was wrong, oh ow
                    mapUnkIds[(*it).first] = nIds;
                    CAddrInfo &info = (*it).second;
                    if (info.nRefCount)
                    {
                        READWRITE(info);
                        nIds++;
                    }
                }
                nIds = 0;
                for (std::map<int, CAddrInfo>::iterator it = am->mapInfo.begin(); it != am->mapInfo.end(); it++)
                {
                    if (nIds == nTried) break; // this means nTried was wrong, oh ow
                    CAddrInfo &info = (*it).second;
                    if (info.fInTried)
                    {
                        READWRITE(info);
                        nIds++;
                    }
                }
                for (std::vector<std::set<int> >::iterator it = am->vvNew.begin(); it != am->vvNew.end(); it++)
                {
                    const std::set<int> &vNew = (*it);
                    int nSize = vNew.size();
                    READWRITE(nSize);
                    for (std::set<int>::iterator it2 = vNew.begin(); it2 != vNew.end(); it2++)
                    {
                        int nIndex = mapUnkIds[*it2];
                        READWRITE(nIndex);
                    }
                }
            } else {
                int nUBuckets = 0;
                READWRITE(nUBuckets);
                am->nIdCount = 0;
                am->mapInfo.clear();
                am->mapAddr.clear();
                am->vRandom.clear();
                am->vvTried = std::vector<std::vector<int> >(ADDRMAN_TRIED_BUCKET_COUNT, std::vector<int>(0));
                am->vvNew = std::vector<std::set<int> >(ADDRMAN_NEW_BUCKET_COUNT, std::set<int>());
                for (int n = 0; n < am->nNew; n++)
                {
                    CAddrInfo &info = am->mapInfo[n];
                    READWRITE(info);
                    am->mapAddr[info] = n;
                    info.nRandomPos = vRandom.size();
                    am->vRandom.push_back(n);
                    if (nUBuckets != ADDRMAN_NEW_BUCKET_COUNT)
                    {
                        am->vvNew[info.GetNewBucket(am->nKey)].insert(n);
                        info.nRefCount++;
                    }
                }
                am->nIdCount = am->nNew;
                int nLost = 0;
                for (int n = 0; n < am->nTried; n++)
                {
                    CAddrInfo info;
                    READWRITE(info);
                    std::vector<int> &vTried = am->vvTried[info.GetTriedBucket(am->nKey)];
                    if (vTried.size() < ADDRMAN_TRIED_BUCKET_SIZE)
                    {
                        info.nRandomPos = vRandom.size();
                        info.fInTried = true;
                        am->vRandom.push_back(am->nIdCount);
                        am->mapInfo[am->nIdCount] = info;
                        am->mapAddr[info] = am->nIdCount;
                        vTried.push_back(am->nIdCount);
                        am->nIdCount++;
                    } else {
                        nLost++;
                    }
                }
                am->nTried -= nLost;
                for (int b = 0; b < nUBuckets; b++)
                {
                    std::set<int> &vNew = am->vvNew[b];
                    int nSize = 0;
                    READWRITE(nSize);
                    for (int n = 0; n < nSize; n++)
                    {
                        int nIndex = 0;
                        READWRITE(nIndex);
                        CAddrInfo &info = am->mapInfo[nIndex];
                        if (nUBuckets == ADDRMAN_NEW_BUCKET_COUNT && info.nRefCount < ADDRMAN_NEW_BUCKETS_PER_ADDRESS)
                        {
                            info.nRefCount++;
                            vNew.insert(nIndex);
                        }
                    }
                }
            }
        }
    });)

    CAddrMan() : vRandom(0), vvTried(ADDRMAN_TRIED_BUCKET_COUNT, std::vector<int>(0)), vvNew(ADDRMAN_NEW_BUCKET_COUNT, std::set<int>())
    {
         nKey.resize(32);
         RAND_bytes(&nKey[0], 32);

         nIdCount = 0;
         nTried = 0;
         nNew = 0;
    }

    // Return the number of (unique) addresses in all tables.
    int size()
    {
        return vRandom.size();
    }

    // Consistency check
    void Check()
    {
#ifdef DEBUG_ADDRMAN
        {
            LOCK(cs);
            int err;
            if ((err=Check_()))
                printf("ADDRMAN CONSISTENCY CHECK FAILED!!! err=%i\n", err);
        }
#endif
    }

    // Add a single address.
    bool Add(const CAddress &addr, const CNetAddr& source, int64 nTimePenalty = 0)
    {
        bool fRet = false;
        {
            LOCK(cs);
            Check();
            fRet |= Add_(addr, source, nTimePenalty);
            Check();
        }
        if (fRet)
            printf("Added %s from %s: %i tried, %i new\n", addr.ToStringIPPort().c_str(), source.ToString().c_str(), nTried, nNew);
        return fRet;
    }

    // Add multiple addresses.
    bool Add(const std::vector<CAddress> &vAddr, const CNetAddr& source, int64 nTimePenalty = 0)
    {
        int nAdd = 0;
        {
            LOCK(cs);
            Check();
            for (std::vector<CAddress>::const_iterator it = vAddr.begin(); it != vAddr.end(); it++)
                nAdd += Add_(*it, source, nTimePenalty) ? 1 : 0;
            Check();
        }
        if (nAdd)
            printf("Added %i addresses from %s: %i tried, %i new\n", nAdd, source.ToString().c_str(), nTried, nNew);
        return nAdd > 0;
    }

    // Mark an entry as accessible.
    void Good(const CService &addr, int64 nTime = GetAdjustedTime())
    {
        {
            LOCK(cs);
            Check();
            Good_(addr, nTime);
            Check();
        }
    }

    // Mark an entry as connection attempted to.
    void Attempt(const CService &addr, int64 nTime = GetAdjustedTime())
    {
        {
            LOCK(cs);
            Check();
            Attempt_(addr, nTime);
            Check();
        }
    }

    // Choose an address to connect to.
    // nUnkBias determines how much "new" entries are favored over "tried" ones (0-100).
    CAddress Select(int nUnkBias = 50)
    {
        CAddress addrRet;
        {
            LOCK(cs);
            Check();
            addrRet = Select_(nUnkBias);
            Check();
        }
        return addrRet;
    }

    // Return a bunch of addresses, selected at random.
    std::vector<CAddress> GetAddr()
    {
        Check();
        std::vector<CAddress> vAddr;
        {
            LOCK(cs);
            GetAddr_(vAddr);
        }
        Check();
        return vAddr;
    }

    // Mark an entry as currently-connected-to.
    void Connected(const CService &addr, int64 nTime = GetAdjustedTime())
    {
        {
            LOCK(cs);
            Check();
            Connected_(addr, nTime);
            Check();
        }
    }
};

#endif