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bitcoin/src/addrman.h

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// Copyright (c) 2012 Pieter Wuille
// Copyright (c) 2012-2019 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_ADDRMAN_H
#define BITCOIN_ADDRMAN_H
#include <netaddress.h>
#include <protocol.h>
#include <random.h>
#include <sync.h>
#include <timedata.h>
#include <util/system.h>
#include <map>
#include <set>
#include <stdint.h>
#include <vector>
/**
* Extended statistics about a CAddress
*/
class CAddrInfo : public CAddress
{
public:
//! last try whatsoever by us (memory only)
int64_t nLastTry{0};
//! last counted attempt (memory only)
int64_t nLastCountAttempt{0};
private:
//! where knowledge about this address first came from
CNetAddr source;
//! last successful connection by us
int64_t nLastSuccess{0};
//! connection attempts since last successful attempt
int nAttempts{0};
//! reference count in new sets (memory only)
int nRefCount{0};
//! in tried set? (memory only)
bool fInTried{false};
//! position in vRandom
int nRandomPos{-1};
friend class CAddrMan;
public:
ADD_SERIALIZE_METHODS;
template <typename Stream, typename Operation>
inline void SerializationOp(Stream& s, Operation ser_action) {
READWRITEAS(CAddress, *this);
READWRITE(source);
READWRITE(nLastSuccess);
READWRITE(nAttempts);
}
CAddrInfo(const CAddress &addrIn, const CNetAddr &addrSource) : CAddress(addrIn), source(addrSource)
{
}
CAddrInfo() : CAddress(), source()
{
}
//! Calculate in which "tried" bucket this entry belongs
int GetTriedBucket(const uint256 &nKey) const;
//! Calculate in which "new" bucket this entry belongs, given a certain source
int GetNewBucket(const uint256 &nKey, const CNetAddr& src) const;
//! Calculate in which "new" bucket this entry belongs, using its default source
int GetNewBucket(const uint256 &nKey) const
{
return GetNewBucket(nKey, source);
}
//! Calculate in which position of a bucket to store this entry.
int GetBucketPosition(const uint256 &nKey, bool fNew, int nBucket) const;
//! 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:
* * Keep the address tables in-memory, and asynchronously dump the entire table to peers.dat.
* * Make sure no (localized) attacker can fill the entire table with his nodes/addresses.
*
* To that end:
* * Addresses are organized into buckets.
* * Addresses that have not yet been tried go into 1024 "new" buckets.
* * Based on the address range (/16 for IPv4) of the source of information, 64 buckets are selected at random.
* * The actual bucket is chosen from one of these, based on the range in which the address itself is located.
* * One single address can occur in up to 8 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 256 "tried" buckets.
* * Each address range selects at random 8 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_LOG2 8
//! total number of buckets for new addresses
#define ADDRMAN_NEW_BUCKET_COUNT_LOG2 10
//! maximum allowed number of entries in buckets for new and tried addresses
#define ADDRMAN_BUCKET_SIZE_LOG2 6
//! over how many buckets entries with tried addresses from a single group (/16 for IPv4) are spread
#define ADDRMAN_TRIED_BUCKETS_PER_GROUP 8
//! over how many buckets entries with new addresses originating from a single group are spread
#define ADDRMAN_NEW_BUCKETS_PER_SOURCE_GROUP 64
//! in how many buckets for entries with new addresses a single address may occur
#define ADDRMAN_NEW_BUCKETS_PER_ADDRESS 8
//! 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
//! how recent a successful connection should be before we allow an address to be evicted from tried
#define ADDRMAN_REPLACEMENT_HOURS 4
//! 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
//! Convenience
#define ADDRMAN_TRIED_BUCKET_COUNT (1 << ADDRMAN_TRIED_BUCKET_COUNT_LOG2)
#define ADDRMAN_NEW_BUCKET_COUNT (1 << ADDRMAN_NEW_BUCKET_COUNT_LOG2)
#define ADDRMAN_BUCKET_SIZE (1 << ADDRMAN_BUCKET_SIZE_LOG2)
//! the maximum number of tried addr collisions to store
#define ADDRMAN_SET_TRIED_COLLISION_SIZE 10
//! the maximum time we'll spend trying to resolve a tried table collision, in seconds
static const int64_t ADDRMAN_TEST_WINDOW = 40*60; // 40 minutes
/**
* Stochastical (IP) address manager
*/
class CAddrMan
{
protected:
//! critical section to protect the inner data structures
mutable CCriticalSection cs;
private:
//! last used nId
int nIdCount GUARDED_BY(cs);
//! table with information about all nIds
std::map<int, CAddrInfo> mapInfo GUARDED_BY(cs);
//! find an nId based on its network address
std::map<CNetAddr, int> mapAddr GUARDED_BY(cs);
//! randomly-ordered vector of all nIds
std::vector<int> vRandom GUARDED_BY(cs);
// number of "tried" entries
int nTried GUARDED_BY(cs);
//! list of "tried" buckets
int vvTried[ADDRMAN_TRIED_BUCKET_COUNT][ADDRMAN_BUCKET_SIZE] GUARDED_BY(cs);
//! number of (unique) "new" entries
int nNew GUARDED_BY(cs);
//! list of "new" buckets
int vvNew[ADDRMAN_NEW_BUCKET_COUNT][ADDRMAN_BUCKET_SIZE] GUARDED_BY(cs);
//! last time Good was called (memory only)
int64_t nLastGood GUARDED_BY(cs);
//! Holds addrs inserted into tried table that collide with existing entries. Test-before-evict discipline used to resolve these collisions.
std::set<int> m_tried_collisions;
protected:
//! secret key to randomize bucket select with
uint256 nKey;
//! Source of random numbers for randomization in inner loops
FastRandomContext insecure_rand;
//! Find an entry.
CAddrInfo* Find(const CNetAddr& addr, int *pnId = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! find an entry, creating it if necessary.
//! nTime and nServices of the found node are updated, if necessary.
CAddrInfo* Create(const CAddress &addr, const CNetAddr &addrSource, int *pnId = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Swap two elements in vRandom.
void SwapRandom(unsigned int nRandomPos1, unsigned int nRandomPos2) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Move an entry from the "new" table(s) to the "tried" table
void MakeTried(CAddrInfo& info, int nId) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Delete an entry. It must not be in tried, and have refcount 0.
void Delete(int nId) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Clear a position in a "new" table. This is the only place where entries are actually deleted.
void ClearNew(int nUBucket, int nUBucketPos) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Mark an entry "good", possibly moving it from "new" to "tried".
void Good_(const CService &addr, bool test_before_evict, int64_t time) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Add an entry to the "new" table.
bool Add_(const CAddress &addr, const CNetAddr& source, int64_t nTimePenalty) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Mark an entry as attempted to connect.
void Attempt_(const CService &addr, bool fCountFailure, int64_t nTime) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Select an address to connect to, if newOnly is set to true, only the new table is selected from.
CAddrInfo Select_(bool newOnly) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! See if any to-be-evicted tried table entries have been tested and if so resolve the collisions.
void ResolveCollisions_() EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Return a random to-be-evicted tried table address.
CAddrInfo SelectTriedCollision_() EXCLUSIVE_LOCKS_REQUIRED(cs);
#ifdef DEBUG_ADDRMAN
//! Perform consistency check. Returns an error code or zero.
int Check_() EXCLUSIVE_LOCKS_REQUIRED(cs);
#endif
//! Select several addresses at once.
void GetAddr_(std::vector<CAddress> &vAddr) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Mark an entry as currently-connected-to.
void Connected_(const CService &addr, int64_t nTime) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Update an entry's service bits.
void SetServices_(const CService &addr, ServiceFlags nServices) EXCLUSIVE_LOCKS_REQUIRED(cs);
public:
/**
* serialized format:
* * version byte (currently 1)
* * 0x20 + nKey (serialized as if it were a vector, for backward compatibility)
* * nNew
* * nTried
* * number of "new" buckets XOR 2**30
* * all nNew addrinfos in vvNew
* * all nTried addrinfos in vvTried
* * for each bucket:
* * number of elements
* * for each element: index
*
* 2**30 is xorred with the number of buckets to make addrman deserializer v0 detect it
* as incompatible. This is necessary because it did not check the version number on
* deserialization.
*
* 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_UNKNOWN_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.
*
* We don't use ADD_SERIALIZE_METHODS since the serialization and deserialization code has
* very little in common.
*/
template<typename Stream>
void Serialize(Stream &s) const
{
LOCK(cs);
unsigned char nVersion = 1;
s << nVersion;
s << ((unsigned char)32);
s << nKey;
s << nNew;
s << nTried;
int nUBuckets = ADDRMAN_NEW_BUCKET_COUNT ^ (1 << 30);
s << nUBuckets;
std::map<int, int> mapUnkIds;
int nIds = 0;
for (const auto& entry : mapInfo) {
mapUnkIds[entry.first] = nIds;
const CAddrInfo &info = entry.second;
if (info.nRefCount) {
assert(nIds != nNew); // this means nNew was wrong, oh ow
s << info;
nIds++;
}
}
nIds = 0;
for (const auto& entry : mapInfo) {
const CAddrInfo &info = entry.second;
if (info.fInTried) {
assert(nIds != nTried); // this means nTried was wrong, oh ow
s << info;
nIds++;
}
}
for (int bucket = 0; bucket < ADDRMAN_NEW_BUCKET_COUNT; bucket++) {
int nSize = 0;
for (int i = 0; i < ADDRMAN_BUCKET_SIZE; i++) {
if (vvNew[bucket][i] != -1)
nSize++;
}
s << nSize;
for (int i = 0; i < ADDRMAN_BUCKET_SIZE; i++) {
if (vvNew[bucket][i] != -1) {
int nIndex = mapUnkIds[vvNew[bucket][i]];
s << nIndex;
}
}
}
}
template<typename Stream>
void Unserialize(Stream& s)
{
LOCK(cs);
Clear();
unsigned char nVersion;
s >> nVersion;
unsigned char nKeySize;
s >> nKeySize;
if (nKeySize != 32) throw std::ios_base::failure("Incorrect keysize in addrman deserialization");
s >> nKey;
s >> nNew;
s >> nTried;
int nUBuckets = 0;
s >> nUBuckets;
if (nVersion != 0) {
nUBuckets ^= (1 << 30);
}
if (nNew > ADDRMAN_NEW_BUCKET_COUNT * ADDRMAN_BUCKET_SIZE) {
throw std::ios_base::failure("Corrupt CAddrMan serialization, nNew exceeds limit.");
}
if (nTried > ADDRMAN_TRIED_BUCKET_COUNT * ADDRMAN_BUCKET_SIZE) {
throw std::ios_base::failure("Corrupt CAddrMan serialization, nTried exceeds limit.");
}
// Deserialize entries from the new table.
for (int n = 0; n < nNew; n++) {
CAddrInfo &info = mapInfo[n];
s >> info;
mapAddr[info] = n;
info.nRandomPos = vRandom.size();
vRandom.push_back(n);
if (nVersion != 1 || nUBuckets != ADDRMAN_NEW_BUCKET_COUNT) {
// In case the new table data cannot be used (nVersion unknown, or bucket count wrong),
// immediately try to give them a reference based on their primary source address.
int nUBucket = info.GetNewBucket(nKey);
int nUBucketPos = info.GetBucketPosition(nKey, true, nUBucket);
if (vvNew[nUBucket][nUBucketPos] == -1) {
vvNew[nUBucket][nUBucketPos] = n;
info.nRefCount++;
}
}
}
nIdCount = nNew;
// Deserialize entries from the tried table.
int nLost = 0;
for (int n = 0; n < nTried; n++) {
CAddrInfo info;
s >> info;
int nKBucket = info.GetTriedBucket(nKey);
int nKBucketPos = info.GetBucketPosition(nKey, false, nKBucket);
if (vvTried[nKBucket][nKBucketPos] == -1) {
info.nRandomPos = vRandom.size();
info.fInTried = true;
vRandom.push_back(nIdCount);
mapInfo[nIdCount] = info;
mapAddr[info] = nIdCount;
vvTried[nKBucket][nKBucketPos] = nIdCount;
nIdCount++;
} else {
nLost++;
}
}
nTried -= nLost;
// Deserialize positions in the new table (if possible).
for (int bucket = 0; bucket < nUBuckets; bucket++) {
int nSize = 0;
s >> nSize;
for (int n = 0; n < nSize; n++) {
int nIndex = 0;
s >> nIndex;
if (nIndex >= 0 && nIndex < nNew) {
CAddrInfo &info = mapInfo[nIndex];
int nUBucketPos = info.GetBucketPosition(nKey, true, bucket);
if (nVersion == 1 && nUBuckets == ADDRMAN_NEW_BUCKET_COUNT && vvNew[bucket][nUBucketPos] == -1 && info.nRefCount < ADDRMAN_NEW_BUCKETS_PER_ADDRESS) {
info.nRefCount++;
vvNew[bucket][nUBucketPos] = nIndex;
}
}
}
}
// Prune new entries with refcount 0 (as a result of collisions).
int nLostUnk = 0;
for (std::map<int, CAddrInfo>::const_iterator it = mapInfo.begin(); it != mapInfo.end(); ) {
if (it->second.fInTried == false && it->second.nRefCount == 0) {
std::map<int, CAddrInfo>::const_iterator itCopy = it++;
Delete(itCopy->first);
nLostUnk++;
} else {
it++;
}
}
if (nLost + nLostUnk > 0) {
LogPrint(BCLog::ADDRMAN, "addrman lost %i new and %i tried addresses due to collisions\n", nLostUnk, nLost);
}
Check();
}
void Clear()
{
LOCK(cs);
std::vector<int>().swap(vRandom);
nKey = insecure_rand.rand256();
for (size_t bucket = 0; bucket < ADDRMAN_NEW_BUCKET_COUNT; bucket++) {
for (size_t entry = 0; entry < ADDRMAN_BUCKET_SIZE; entry++) {
vvNew[bucket][entry] = -1;
}
}
for (size_t bucket = 0; bucket < ADDRMAN_TRIED_BUCKET_COUNT; bucket++) {
for (size_t entry = 0; entry < ADDRMAN_BUCKET_SIZE; entry++) {
vvTried[bucket][entry] = -1;
}
}
nIdCount = 0;
nTried = 0;
nNew = 0;
nLastGood = 1; //Initially at 1 so that "never" is strictly worse.
mapInfo.clear();
mapAddr.clear();
}
CAddrMan()
{
Clear();
}
~CAddrMan()
{
nKey.SetNull();
}
//! Return the number of (unique) addresses in all tables.
size_t size() const
{
LOCK(cs); // TODO: Cache this in an atomic to avoid this overhead
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)
{
LOCK(cs);
bool fRet = false;
Check();
fRet |= Add_(addr, source, nTimePenalty);
Check();
if (fRet) {
LogPrint(BCLog::ADDRMAN, "Added %s from %s: %i tried, %i new\n", addr.ToStringIPPort(), source.ToString(), nTried, nNew);
}
return fRet;
}
//! Add multiple addresses.
bool Add(const std::vector<CAddress> &vAddr, const CNetAddr& source, int64_t nTimePenalty = 0)
{
LOCK(cs);
int nAdd = 0;
Check();
for (std::vector<CAddress>::const_iterator it = vAddr.begin(); it != vAddr.end(); it++)
nAdd += Add_(*it, source, nTimePenalty) ? 1 : 0;
Check();
if (nAdd) {
LogPrint(BCLog::ADDRMAN, "Added %i addresses from %s: %i tried, %i new\n", nAdd, source.ToString(), nTried, nNew);
}
return nAdd > 0;
}
//! Mark an entry as accessible.
void Good(const CService &addr, bool test_before_evict = true, int64_t nTime = GetAdjustedTime())
{
LOCK(cs);
Check();
Good_(addr, test_before_evict, nTime);
Check();
}
//! Mark an entry as connection attempted to.
void Attempt(const CService &addr, bool fCountFailure, int64_t nTime = GetAdjustedTime())
{
LOCK(cs);
Check();
Attempt_(addr, fCountFailure, nTime);
Check();
}
//! See if any to-be-evicted tried table entries have been tested and if so resolve the collisions.
void ResolveCollisions()
{
LOCK(cs);
Check();
ResolveCollisions_();
Check();
}
//! Randomly select an address in tried that another address is attempting to evict.
CAddrInfo SelectTriedCollision()
{
CAddrInfo ret;
{
LOCK(cs);
Check();
ret = SelectTriedCollision_();
Check();
}
return ret;
}
/**
* Choose an address to connect to.
*/
CAddrInfo Select(bool newOnly = false)
{
CAddrInfo addrRet;
{
LOCK(cs);
Check();
addrRet = Select_(newOnly);
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();
}
void SetServices(const CService &addr, ServiceFlags nServices)
{
LOCK(cs);
Check();
SetServices_(addr, nServices);
Check();
}
};
#endif // BITCOIN_ADDRMAN_H
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