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1// Copyright (c) 2012 Pieter Wuille
2// Distributed under the MIT/X11 software license, see the accompanying
3// file license.txt or http://www.opensource.org/licenses/mit-license.php.
4#ifndef _BITCOIN_ADDRMAN
5#define _BITCOIN_ADDRMAN 1
6
7#include "netbase.h"
8#include "protocol.h"
9#include "util.h"
10
11
12#include <map>
13#include <vector>
14
15#include <openssl/rand.h>
16
17
6b8de05d 18/** Extended statistics about a CAddress */
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19class CAddrInfo : public CAddress
20{
21private:
22 // where knowledge about this address first came from
23 CNetAddr source;
24
25 // last succesfull connection by us
26 int64 nLastSuccess;
27
28 // last try whatsoever by us:
29 // int64 CAddress::nLastTry
30
31 // connection attempts since last succesful attempt
32 int nAttempts;
33
34 // reference count in new sets (memory only)
35 int nRefCount;
36
37 // in tried set? (memory only)
38 bool fInTried;
39
40 // position in vRandom
41 int nRandomPos;
42
43 friend class CAddrMan;
44
45public:
46
47 IMPLEMENT_SERIALIZE(
48 CAddress* pthis = (CAddress*)(this);
49 READWRITE(*pthis);
50 READWRITE(source);
51 READWRITE(nLastSuccess);
52 READWRITE(nAttempts);
53 )
54
55 void Init()
56 {
57 nLastSuccess = 0;
58 nLastTry = 0;
59 nAttempts = 0;
60 nRefCount = 0;
61 fInTried = false;
62 nRandomPos = -1;
63 }
64
65 CAddrInfo(const CAddress &addrIn, const CNetAddr &addrSource) : CAddress(addrIn)
66 {
67 Init();
68 }
69
70 CAddrInfo() : CAddress(), source()
71 {
72 Init();
73 }
74
75 // Calculate in which "tried" bucket this entry belongs
76 int GetTriedBucket(const std::vector<unsigned char> &nKey) const;
77
78 // Calculate in which "new" bucket this entry belongs, given a certain source
79 int GetNewBucket(const std::vector<unsigned char> &nKey, const CNetAddr& src) const;
80
81 // Calculate in which "new" bucket this entry belongs, using its default source
82 int GetNewBucket(const std::vector<unsigned char> &nKey) const
83 {
84 return GetNewBucket(nKey, source);
85 }
86
87 // Determine whether the statistics about this entry are bad enough so that it can just be deleted
88 bool IsTerrible(int64 nNow = GetAdjustedTime()) const;
89
90 // Calculate the relative chance this entry should be given when selecting nodes to connect to
91 double GetChance(int64 nNow = GetAdjustedTime()) const;
92
93};
94
95// Stochastic address manager
96//
97// Design goals:
98// * Only keep a limited number of addresses around, so that addr.dat and memory requirements do not grow without bound.
99// * Keep the address tables in-memory, and asynchronously dump the entire to able in addr.dat.
100// * Make sure no (localized) attacker can fill the entire table with his nodes/addresses.
101//
102// To that end:
103// * Addresses are organized into buckets.
104// * Address that have not yet been tried go into 256 "new" buckets.
105// * Based on the address range (/16 for IPv4) of source of the information, 32 buckets are selected at random
106// * The actual bucket is chosen from one of these, based on the range the address itself is located.
107// * One single address can occur in up to 4 different buckets, to increase selection chances for addresses that
108// are seen frequently. The chance for increasing this multiplicity decreases exponentially.
109// * When adding a new address to a full bucket, a randomly chosen entry (with a bias favoring less recently seen
110// ones) is removed from it first.
111// * Addresses of nodes that are known to be accessible go into 64 "tried" buckets.
112// * Each address range selects at random 4 of these buckets.
113// * The actual bucket is chosen from one of these, based on the full address.
114// * When adding a new good address to a full bucket, a randomly chosen entry (with a bias favoring less recently
115// tried ones) is evicted from it, back to the "new" buckets.
116// * Bucket selection is based on cryptographic hashing, using a randomly-generated 256-bit key, which should not
117// be observable by adversaries.
118// * Several indexes are kept for high performance. Defining DEBUG_ADDRMAN will introduce frequent (and expensive)
119// consistency checks for the entire datastructure.
120
121// total number of buckets for tried addresses
122#define ADDRMAN_TRIED_BUCKET_COUNT 64
123
124// maximum allowed number of entries in buckets for tried addresses
125#define ADDRMAN_TRIED_BUCKET_SIZE 64
126
127// total number of buckets for new addresses
128#define ADDRMAN_NEW_BUCKET_COUNT 256
129
130// maximum allowed number of entries in buckets for new addresses
131#define ADDRMAN_NEW_BUCKET_SIZE 64
132
133// over how many buckets entries with tried addresses from a single group (/16 for IPv4) are spread
134#define ADDRMAN_TRIED_BUCKETS_PER_GROUP 4
135
136// over how many buckets entries with new addresses originating from a single group are spread
137#define ADDRMAN_NEW_BUCKETS_PER_SOURCE_GROUP 32
138
139// in how many buckets for entries with new addresses a single address may occur
140#define ADDRMAN_NEW_BUCKETS_PER_ADDRESS 4
141
142// how many entries in a bucket with tried addresses are inspected, when selecting one to replace
143#define ADDRMAN_TRIED_ENTRIES_INSPECT_ON_EVICT 4
144
145// how old addresses can maximally be
146#define ADDRMAN_HORIZON_DAYS 30
147
148// after how many failed attempts we give up on a new node
149#define ADDRMAN_RETRIES 3
150
151// how many successive failures are allowed ...
152#define ADDRMAN_MAX_FAILURES 10
153
154// ... in at least this many days
155#define ADDRMAN_MIN_FAIL_DAYS 7
156
157// the maximum percentage of nodes to return in a getaddr call
158#define ADDRMAN_GETADDR_MAX_PCT 23
159
160// the maximum number of nodes to return in a getaddr call
161#define ADDRMAN_GETADDR_MAX 2500
162
6b8de05d 163/** Stochastical (IP) address manager */
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164class CAddrMan
165{
166private:
167 // critical section to protect the inner data structures
168 mutable CCriticalSection cs;
169
170 // secret key to randomize bucket select with
171 std::vector<unsigned char> nKey;
172
173 // last used nId
174 int nIdCount;
175
176 // table with information about all nId's
177 std::map<int, CAddrInfo> mapInfo;
178
179 // find an nId based on its network address
180 std::map<CNetAddr, int> mapAddr;
181
182 // randomly-ordered vector of all nId's
183 std::vector<int> vRandom;
184
185 // number of "tried" entries
186 int nTried;
187
188 // list of "tried" buckets
189 std::vector<std::vector<int> > vvTried;
190
191 // number of (unique) "new" entries
192 int nNew;
193
194 // list of "new" buckets
195 std::vector<std::set<int> > vvNew;
196
197protected:
198
199 // Find an entry.
200 CAddrInfo* Find(const CNetAddr& addr, int *pnId = NULL);
201
202 // find an entry, creating it if necessary.
203 // nTime and nServices of found node is updated, if necessary.
204 CAddrInfo* Create(const CAddress &addr, const CNetAddr &addrSource, int *pnId = NULL);
205
206 // Swap two elements in vRandom.
207 void SwapRandom(int nRandomPos1, int nRandomPos2);
208
209 // Return position in given bucket to replace.
210 int SelectTried(int nKBucket);
211
212 // Remove an element from a "new" bucket.
213 // This is the only place where actual deletes occur.
214 // They are never deleted while in the "tried" table, only possibly evicted back to the "new" table.
215 int ShrinkNew(int nUBucket);
216
217 // Move an entry from the "new" table(s) to the "tried" table
218 // @pre vvUnkown[nOrigin].count(nId) != 0
219 void MakeTried(CAddrInfo& info, int nId, int nOrigin);
220
221 // Mark an entry "good", possibly moving it from "new" to "tried".
222 void Good_(const CService &addr, int64 nTime);
223
224 // Add an entry to the "new" table.
225 bool Add_(const CAddress &addr, const CNetAddr& source, int64 nTimePenalty);
226
227 // Mark an entry as attempted to connect.
228 void Attempt_(const CService &addr, int64 nTime);
229
230 // Select an address to connect to.
231 // nUnkBias determines how much to favor new addresses over tried ones (min=0, max=100)
232 CAddress Select_(int nUnkBias);
233
234#ifdef DEBUG_ADDRMAN
235 // Perform consistency check. Returns an error code or zero.
236 int Check_();
237#endif
238
239 // Select several addresses at once.
240 void GetAddr_(std::vector<CAddress> &vAddr);
241
242 // Mark an entry as currently-connected-to.
243 void Connected_(const CService &addr, int64 nTime);
244
245public:
246
247 IMPLEMENT_SERIALIZE
248 (({
249 // serialized format:
250 // * version byte (currently 0)
251 // * nKey
252 // * nNew
253 // * nTried
254 // * number of "new" buckets
255 // * all nNew addrinfo's in vvNew
256 // * all nTried addrinfo's in vvTried
257 // * for each bucket:
258 // * number of elements
259 // * for each element: index
260 //
261 // Notice that vvTried, mapAddr and vVector are never encoded explicitly;
262 // they are instead reconstructed from the other information.
263 //
264 // vvNew is serialized, but only used if ADDRMAN_UNKOWN_BUCKET_COUNT didn't change,
265 // otherwise it is reconstructed as well.
266 //
267 // This format is more complex, but significantly smaller (at most 1.5 MiB), and supports
268 // changes to the ADDRMAN_ parameters without breaking the on-disk structure.
5fee401f 269 {
f8dcd5ca 270 LOCK(cs);
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271 unsigned char nVersion = 0;
272 READWRITE(nVersion);
273 READWRITE(nKey);
274 READWRITE(nNew);
275 READWRITE(nTried);
276
277 CAddrMan *am = const_cast<CAddrMan*>(this);
278 if (fWrite)
279 {
280 int nUBuckets = ADDRMAN_NEW_BUCKET_COUNT;
281 READWRITE(nUBuckets);
282 std::map<int, int> mapUnkIds;
283 int nIds = 0;
284 for (std::map<int, CAddrInfo>::iterator it = am->mapInfo.begin(); it != am->mapInfo.end(); it++)
285 {
286 if (nIds == nNew) break; // this means nNew was wrong, oh ow
287 mapUnkIds[(*it).first] = nIds;
288 CAddrInfo &info = (*it).second;
289 if (info.nRefCount)
290 {
291 READWRITE(info);
292 nIds++;
293 }
294 }
295 nIds = 0;
296 for (std::map<int, CAddrInfo>::iterator it = am->mapInfo.begin(); it != am->mapInfo.end(); it++)
297 {
298 if (nIds == nTried) break; // this means nTried was wrong, oh ow
299 CAddrInfo &info = (*it).second;
300 if (info.fInTried)
301 {
302 READWRITE(info);
303 nIds++;
304 }
305 }
306 for (std::vector<std::set<int> >::iterator it = am->vvNew.begin(); it != am->vvNew.end(); it++)
307 {
308 const std::set<int> &vNew = (*it);
309 int nSize = vNew.size();
310 READWRITE(nSize);
311 for (std::set<int>::iterator it2 = vNew.begin(); it2 != vNew.end(); it2++)
312 {
313 int nIndex = mapUnkIds[*it2];
314 READWRITE(nIndex);
315 }
316 }
317 } else {
318 int nUBuckets = 0;
319 READWRITE(nUBuckets);
320 am->nIdCount = 0;
321 am->mapInfo.clear();
322 am->mapAddr.clear();
323 am->vRandom.clear();
324 am->vvTried = std::vector<std::vector<int> >(ADDRMAN_TRIED_BUCKET_COUNT, std::vector<int>(0));
325 am->vvNew = std::vector<std::set<int> >(ADDRMAN_NEW_BUCKET_COUNT, std::set<int>());
326 for (int n = 0; n < am->nNew; n++)
327 {
328 CAddrInfo &info = am->mapInfo[n];
329 READWRITE(info);
330 am->mapAddr[info] = n;
331 info.nRandomPos = vRandom.size();
332 am->vRandom.push_back(n);
333 if (nUBuckets != ADDRMAN_NEW_BUCKET_COUNT)
334 {
335 am->vvNew[info.GetNewBucket(am->nKey)].insert(n);
336 info.nRefCount++;
337 }
338 }
339 am->nIdCount = am->nNew;
340 int nLost = 0;
341 for (int n = 0; n < am->nTried; n++)
342 {
343 CAddrInfo info;
344 READWRITE(info);
345 std::vector<int> &vTried = am->vvTried[info.GetTriedBucket(am->nKey)];
346 if (vTried.size() < ADDRMAN_TRIED_BUCKET_SIZE)
347 {
348 info.nRandomPos = vRandom.size();
349 info.fInTried = true;
350 am->vRandom.push_back(am->nIdCount);
351 am->mapInfo[am->nIdCount] = info;
352 am->mapAddr[info] = am->nIdCount;
353 vTried.push_back(am->nIdCount);
354 am->nIdCount++;
355 } else {
356 nLost++;
357 }
358 }
359 am->nTried -= nLost;
360 for (int b = 0; b < nUBuckets; b++)
361 {
362 std::set<int> &vNew = am->vvNew[b];
363 int nSize = 0;
364 READWRITE(nSize);
365 for (int n = 0; n < nSize; n++)
366 {
367 int nIndex = 0;
368 READWRITE(nIndex);
369 CAddrInfo &info = am->mapInfo[nIndex];
370 if (nUBuckets == ADDRMAN_NEW_BUCKET_COUNT && info.nRefCount < ADDRMAN_NEW_BUCKETS_PER_ADDRESS)
371 {
372 info.nRefCount++;
373 vNew.insert(nIndex);
374 }
375 }
376 }
377 }
378 }
379 });)
380
381 CAddrMan() : vRandom(0), vvTried(ADDRMAN_TRIED_BUCKET_COUNT, std::vector<int>(0)), vvNew(ADDRMAN_NEW_BUCKET_COUNT, std::set<int>())
382 {
383 nKey.resize(32);
384 RAND_bytes(&nKey[0], 32);
385
386 nIdCount = 0;
387 nTried = 0;
388 nNew = 0;
389 }
390
391 // Return the number of (unique) addresses in all tables.
392 int size()
393 {
394 return vRandom.size();
395 }
396
397 // Consistency check
398 void Check()
399 {
400#ifdef DEBUG_ADDRMAN
5fee401f 401 {
f8dcd5ca 402 LOCK(cs);
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403 int err;
404 if ((err=Check_()))
405 printf("ADDRMAN CONSISTENCY CHECK FAILED!!! err=%i\n", err);
406 }
407#endif
408 }
409
410 // Add a single address.
411 bool Add(const CAddress &addr, const CNetAddr& source, int64 nTimePenalty = 0)
412 {
413 bool fRet = false;
5fee401f 414 {
f8dcd5ca 415 LOCK(cs);
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416 Check();
417 fRet |= Add_(addr, source, nTimePenalty);
418 Check();
419 }
420 if (fRet)
421 printf("Added %s from %s: %i tried, %i new\n", addr.ToStringIPPort().c_str(), source.ToString().c_str(), nTried, nNew);
422 return fRet;
423 }
424
425 // Add multiple addresses.
426 bool Add(const std::vector<CAddress> &vAddr, const CNetAddr& source, int64 nTimePenalty = 0)
427 {
428 int nAdd = 0;
5fee401f 429 {
f8dcd5ca 430 LOCK(cs);
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431 Check();
432 for (std::vector<CAddress>::const_iterator it = vAddr.begin(); it != vAddr.end(); it++)
433 nAdd += Add_(*it, source, nTimePenalty) ? 1 : 0;
434 Check();
435 }
436 if (nAdd)
437 printf("Added %i addresses from %s: %i tried, %i new\n", nAdd, source.ToString().c_str(), nTried, nNew);
438 return nAdd > 0;
439 }
440
441 // Mark an entry as accessible.
442 void Good(const CService &addr, int64 nTime = GetAdjustedTime())
443 {
5fee401f 444 {
f8dcd5ca 445 LOCK(cs);
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446 Check();
447 Good_(addr, nTime);
448 Check();
449 }
450 }
451
452 // Mark an entry as connection attempted to.
453 void Attempt(const CService &addr, int64 nTime = GetAdjustedTime())
454 {
5fee401f 455 {
f8dcd5ca 456 LOCK(cs);
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457 Check();
458 Attempt_(addr, nTime);
459 Check();
460 }
461 }
462
463 // Choose an address to connect to.
464 // nUnkBias determines how much "new" entries are favored over "tried" ones (0-100).
465 CAddress Select(int nUnkBias = 50)
466 {
467 CAddress addrRet;
5fee401f 468 {
f8dcd5ca 469 LOCK(cs);
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470 Check();
471 addrRet = Select_(nUnkBias);
472 Check();
473 }
474 return addrRet;
475 }
476
477 // Return a bunch of addresses, selected at random.
478 std::vector<CAddress> GetAddr()
479 {
480 Check();
481 std::vector<CAddress> vAddr;
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482 {
483 LOCK(cs);
5fee401f 484 GetAddr_(vAddr);
f8dcd5ca 485 }
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486 Check();
487 return vAddr;
488 }
489
490 // Mark an entry as currently-connected-to.
491 void Connected(const CService &addr, int64 nTime = GetAdjustedTime())
492 {
5fee401f 493 {
f8dcd5ca 494 LOCK(cs);
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495 Check();
496 Connected_(addr, nTime);
497 Check();
498 }
499 }
500};
501
502#endif
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