src/addrman.h
// 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_t nLastSuccess;
// last try whatsoever by us:
// int64_t 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_t nNow = GetAdjustedTime()) const;
// Calculate the relative chance this entry should be given when selecting nodes to connect to
double GetChance(int64_t 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 nIds
std::map<int, CAddrInfo> mapInfo;
// find an nId based on its network address
std::map<CNetAddr, int> mapAddr;
// randomly-ordered vector of all nIds
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_t nTime);
// Add an entry to the "new" table.
bool Add_(const CAddress &addr, const CNetAddr& source, int64_t nTimePenalty);
// Mark an entry as attempted to connect.
void Attempt_(const CService &addr, int64_t 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_t nTime);
public:
IMPLEMENT_SERIALIZE
(({
// serialized format:
// * version byte (currently 0)
// * nKey
// * nNew
// * nTried
// * number of "new" buckets
// * all nNew addrinfos in vvNew
// * all nTried addrinfos 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_()))
LogPrintf("ADDRMAN CONSISTENCY CHECK FAILED!!! err=%i\n", err);
}
#endif
}
// Add a single address.
bool Add(const CAddress &addr, const CNetAddr& source, int64_t nTimePenalty = 0)
{
bool fRet = false;
{
LOCK(cs);
Check();
fRet |= Add_(addr, source, nTimePenalty);
Check();
}
if (fRet)
LogPrintf("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_t 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)
LogPrintf("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_t nTime = GetAdjustedTime())
{
{
LOCK(cs);
Check();
Good_(addr, nTime);
Check();
}
}
// Mark an entry as connection attempted to.
void Attempt(const CService &addr, int64_t 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_t nTime = GetAdjustedTime())
{
{
LOCK(cs);
Check();
Connected_(addr, nTime);
Check();
}
}
};
#endif