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+// Copyright (c) 2012 Pieter Wuille
+// Distributed under the MIT/X11 software license, see the accompanying
+// file license.txt 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 <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 succesfull connection by us
+ int64 nLastSuccess;
+
+ // last try whatsoever by us:
+ // int64 CAddress::nLastTry
+
+ // connection attempts since last succesful 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)
+ {
+ 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 datastructure.
+
+// 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
+
+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(int nRandomPos1, 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.
+ CRITICAL_BLOCK(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
+ CRITICAL_BLOCK(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;
+ CRITICAL_BLOCK(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;
+ CRITICAL_BLOCK(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())
+ {
+ CRITICAL_BLOCK(cs)
+ {
+ Check();
+ Good_(addr, nTime);
+ Check();
+ }
+ }
+
+ // Mark an entry as connection attempted to.
+ void Attempt(const CService &addr, int64 nTime = GetAdjustedTime())
+ {
+ CRITICAL_BLOCK(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;
+ CRITICAL_BLOCK(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;
+ CRITICAL_BLOCK(cs)
+ GetAddr_(vAddr);
+ Check();
+ return vAddr;
+ }
+
+ // Mark an entry as currently-connected-to.
+ void Connected(const CService &addr, int64 nTime = GetAdjustedTime())
+ {
+ CRITICAL_BLOCK(cs)
+ {
+ Check();
+ Connected_(addr, nTime);
+ Check();
+ }
+ }
+};
+
+#endif