addrman.cpp

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// Copyright (c) 2012 Pieter Wuille
// Copyright (c) 2012-2016 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
#include <addrman.h>
#include <addrman_impl.h>
 
#include <hash.h>
#include <logging.h>
#include <logging/timer.h>
#include <netaddress.h>
#include <protocol.h>
#include <random.h>
#include <serialize.h>
#include <streams.h>
#include <timedata.h>
#include <tinyformat.h>
#include <uint256.h>
#include <util/check.h>
 
#include <cmath>
#include <optional>
 
static constexpr uint32_t ADDRMAN_TRIED_BUCKETS_PER_GROUP{8};
static constexpr uint32_t ADDRMAN_NEW_BUCKETS_PER_SOURCE_GROUP{64};
static constexpr int32_t ADDRMAN_NEW_BUCKETS_PER_ADDRESS{8};
static constexpr auto ADDRMAN_HORIZON{30 * 24h};
static constexpr int32_t ADDRMAN_RETRIES{3};
static constexpr int32_t ADDRMAN_MAX_FAILURES{10};
static constexpr auto ADDRMAN_MIN_FAIL{7 * 24h};
static constexpr auto ADDRMAN_REPLACEMENT{4h};
static constexpr size_t ADDRMAN_SET_TRIED_COLLISION_SIZE{10};
static constexpr auto ADDRMAN_TEST_WINDOW{40min};
 
int AddrInfo::GetTriedBucket(const uint256 &nKey,
                             const std::vector<bool> &asmap) const {
    uint64_t hash1 =
        (CHashWriter(SER_GETHASH, 0) << nKey << GetKey()).GetCheapHash();
    uint64_t hash2 = (CHashWriter(SER_GETHASH, 0)
                      << nKey << GetGroup(asmap)
                      << (hash1 % ADDRMAN_TRIED_BUCKETS_PER_GROUP))
                         .GetCheapHash();
    return hash2 % ADDRMAN_TRIED_BUCKET_COUNT;
}
 
int AddrInfo::GetNewBucket(const uint256 &nKey, const CNetAddr &src,
                           const std::vector<bool> &asmap) const {
    std::vector<uint8_t> vchSourceGroupKey = src.GetGroup(asmap);
    uint64_t hash1 = (CHashWriter(SER_GETHASH, 0)
                      << nKey << GetGroup(asmap) << vchSourceGroupKey)
                         .GetCheapHash();
    uint64_t hash2 = (CHashWriter(SER_GETHASH, 0)
                      << nKey << vchSourceGroupKey
                      << (hash1 % ADDRMAN_NEW_BUCKETS_PER_SOURCE_GROUP))
                         .GetCheapHash();
    return hash2 % ADDRMAN_NEW_BUCKET_COUNT;
}
 
int AddrInfo::GetBucketPosition(const uint256 &nKey, bool fNew,
                                int nBucket) const {
    uint64_t hash1 =
        (CHashWriter(SER_GETHASH, 0)
         << nKey << (fNew ? uint8_t{'N'} : uint8_t{'K'}) << nBucket << GetKey())
            .GetCheapHash();
    return hash1 % ADDRMAN_BUCKET_SIZE;
}
 
bool AddrInfo::IsTerrible(NodeSeconds now) const {
    // never remove things tried in the last minute
    if (now - m_last_try <= 1min) {
        return false;
    }
 
    // came in a flying DeLorean
    if (nTime > now + 10min) {
        return true;
    }
 
    // not seen in recent history
    if (now - nTime > ADDRMAN_HORIZON) {
        return true;
    }
 
    // tried N times and never a success
    if (TicksSinceEpoch<std::chrono::seconds>(m_last_success) == 0 &&
        nAttempts >= ADDRMAN_RETRIES) {
        return true;
    }
 
    if (now - m_last_success > ADDRMAN_MIN_FAIL &&
        nAttempts >= ADDRMAN_MAX_FAILURES) {
        // N successive failures in the last week
        return true;
    }
 
    return false;
}
 
double AddrInfo::GetChance(NodeSeconds now) const {
    double fChance = 1.0;
 
    // deprioritize very recent attempts away
    if (now - m_last_try < 10min) {
        fChance *= 0.01;
    }
 
    // deprioritize 66% after each failed attempt, but at most 1/28th to avoid
    // the search taking forever or overly penalizing outages.
    fChance *= std::pow(0.66, std::min(nAttempts, 8));
 
    return fChance;
}
 
AddrManImpl::AddrManImpl(std::vector<bool> &&asmap,
                         int32_t consistency_check_ratio)
    : m_consistency_check_ratio{consistency_check_ratio}, m_asmap{std::move(
                                                              asmap)} {}
 
AddrManImpl::~AddrManImpl() {
    nKey.SetNull();
}
 
template <typename Stream> void AddrManImpl::Serialize(Stream &s_) const {
    LOCK(cs);
 
    // Always serialize in the latest version (FILE_FORMAT).
 
    OverrideStream<Stream> s(&s_, s_.GetType(),
                             s_.GetVersion() | ADDRV2_FORMAT);
 
    s << static_cast<uint8_t>(FILE_FORMAT);
 
    // Increment `lowest_compatible` iff a newly introduced format is
    // incompatible with the previous one.
    static constexpr uint8_t lowest_compatible = Format::V4_MULTIPORT;
    s << static_cast<uint8_t>(INCOMPATIBILITY_BASE + lowest_compatible);
 
    s << nKey;
    s << nNew;
    s << nTried;
 
    int nUBuckets = ADDRMAN_NEW_BUCKET_COUNT ^ (1 << 30);
    s << nUBuckets;
    std::unordered_map<int, int> mapUnkIds;
    int nIds = 0;
    for (const auto &entry : mapInfo) {
        mapUnkIds[entry.first] = nIds;
        const AddrInfo &info = entry.second;
        if (info.nRefCount) {
            // this means nNew was wrong, oh ow
            assert(nIds != nNew);
            s << info;
            nIds++;
        }
    }
    nIds = 0;
    for (const auto &entry : mapInfo) {
        const AddrInfo &info = entry.second;
        if (info.fInTried) {
            // this means nTried was wrong, oh ow
            assert(nIds != nTried);
            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;
            }
        }
    }
    // Store asmap checksum after bucket entries so that it
    // can be ignored by older clients for backward compatibility.
    uint256 asmap_checksum;
    if (m_asmap.size() != 0) {
        asmap_checksum = SerializeHash(m_asmap);
    }
    s << asmap_checksum;
}
 
template <typename Stream> void AddrManImpl::Unserialize(Stream &s_) {
    LOCK(cs);
 
    assert(vRandom.empty());
 
    Format format;
    s_ >> Using<CustomUintFormatter<1>>(format);
 
    int stream_version = s_.GetVersion();
    if (format >= Format::V3_BIP155) {
        // Add ADDRV2_FORMAT to the version so that the CNetAddr and
        // CAddress unserialize methods know that an address in addrv2
        // format is coming.
        stream_version |= ADDRV2_FORMAT;
    }
 
    OverrideStream<Stream> s(&s_, s_.GetType(), stream_version);
 
    uint8_t compat;
    s >> compat;
    if (compat < INCOMPATIBILITY_BASE) {
        throw std::ios_base::failure(
            strprintf("Corrupted addrman database: The compat value (%u) "
                      "is lower than the expected minimum value %u.",
                      compat, INCOMPATIBILITY_BASE));
    }
    const uint8_t lowest_compatible = compat - INCOMPATIBILITY_BASE;
    if (lowest_compatible > FILE_FORMAT) {
        throw InvalidAddrManVersionError(strprintf(
            "Unsupported format of addrman database: %u. It is compatible with "
            "formats >=%u, but the maximum supported by this version of %s is "
            "%u.",
            uint8_t{format}, lowest_compatible, PACKAGE_NAME,
            uint8_t{FILE_FORMAT}));
    }
 
    s >> nKey;
    s >> nNew;
    s >> nTried;
    int nUBuckets = 0;
    s >> nUBuckets;
    if (format >= Format::V1_DETERMINISTIC) {
        nUBuckets ^= (1 << 30);
    }
 
    if (nNew > ADDRMAN_NEW_BUCKET_COUNT * ADDRMAN_BUCKET_SIZE || nNew < 0) {
        throw std::ios_base::failure(strprintf(
            "Corrupt AddrMan serialization: nNew=%d, should be in [0, %d]",
            nNew, ADDRMAN_NEW_BUCKET_COUNT * ADDRMAN_BUCKET_SIZE));
    }
 
    if (nTried > ADDRMAN_TRIED_BUCKET_COUNT * ADDRMAN_BUCKET_SIZE ||
        nTried < 0) {
        throw std::ios_base::failure(strprintf(
            "Corrupt AddrMan serialization: nTried=%d, should be in [0, "
            "%d]",
            nTried, ADDRMAN_TRIED_BUCKET_COUNT * ADDRMAN_BUCKET_SIZE));
    }
 
    // Deserialize entries from the new table.
    for (int n = 0; n < nNew; n++) {
        AddrInfo &info = mapInfo[n];
        s >> info;
        mapAddr[info] = n;
        info.nRandomPos = vRandom.size();
        vRandom.push_back(n);
    }
    nIdCount = nNew;
 
    // Deserialize entries from the tried table.
    int nLost = 0;
    for (int n = 0; n < nTried; n++) {
        AddrInfo info;
        s >> info;
        int nKBucket = info.GetTriedBucket(nKey, m_asmap);
        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;
 
    // Store positions in the new table buckets to apply later (if
    // possible).
    // An entry may appear in up to ADDRMAN_NEW_BUCKETS_PER_ADDRESS buckets,
    // so we store all bucket-entry_index pairs to iterate through later.
    std::vector<std::pair<int, int>> bucket_entries;
 
    for (int bucket = 0; bucket < nUBuckets; ++bucket) {
        int num_entries{0};
        s >> num_entries;
        for (int n = 0; n < num_entries; ++n) {
            int entry_index{0};
            s >> entry_index;
            if (entry_index >= 0 && entry_index < nNew) {
                bucket_entries.emplace_back(bucket, entry_index);
            }
        }
    }
 
    // If the bucket count and asmap checksum haven't changed, then attempt
    // to restore the entries to the buckets/positions they were in before
    // serialization.
    uint256 supplied_asmap_checksum;
    if (m_asmap.size() != 0) {
        supplied_asmap_checksum = SerializeHash(m_asmap);
    }
    uint256 serialized_asmap_checksum;
    if (format >= Format::V2_ASMAP) {
        s >> serialized_asmap_checksum;
    }
    const bool restore_bucketing{nUBuckets == ADDRMAN_NEW_BUCKET_COUNT &&
                                 serialized_asmap_checksum ==
                                     supplied_asmap_checksum};
 
    if (!restore_bucketing) {
        LogPrint(BCLog::ADDRMAN,
                 "Bucketing method was updated, re-bucketing addrman "
                 "entries from disk\n");
    }
 
    for (auto bucket_entry : bucket_entries) {
        int bucket{bucket_entry.first};
        const int entry_index{bucket_entry.second};
        AddrInfo &info = mapInfo[entry_index];
 
        // The entry shouldn't appear in more than
        // ADDRMAN_NEW_BUCKETS_PER_ADDRESS. If it has already, just skip
        // this bucket_entry.
        if (info.nRefCount >= ADDRMAN_NEW_BUCKETS_PER_ADDRESS) {
            continue;
        }
 
        int bucket_position = info.GetBucketPosition(nKey, true, bucket);
        if (restore_bucketing && vvNew[bucket][bucket_position] == -1) {
            // Bucketing has not changed, using existing bucket positions
            // for the new table
            vvNew[bucket][bucket_position] = entry_index;
            ++info.nRefCount;
        } else {
            // In case the new table data cannot be used (bucket count
            // wrong or new asmap), try to give them a reference based on
            // their primary source address.
            bucket = info.GetNewBucket(nKey, m_asmap);
            bucket_position = info.GetBucketPosition(nKey, true, bucket);
            if (vvNew[bucket][bucket_position] == -1) {
                vvNew[bucket][bucket_position] = entry_index;
                ++info.nRefCount;
            }
        }
    }
 
    // Prune new entries with refcount 0 (as a result of collisions).
    int nLostUnk = 0;
    for (auto it = mapInfo.cbegin(); it != mapInfo.cend();) {
        if (it->second.fInTried == false && it->second.nRefCount == 0) {
            const auto 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);
    }
 
    const int check_code{CheckAddrman()};
    if (check_code != 0) {
        throw std::ios_base::failure(strprintf(
            "Corrupt data. Consistency check failed with code %s", check_code));
    }
}
 
AddrInfo *AddrManImpl::Find(const CService &addr, int *pnId) {
    AssertLockHeld(cs);
 
    const auto it = mapAddr.find(addr);
    if (it == mapAddr.end()) {
        return nullptr;
    }
    if (pnId) {
        *pnId = (*it).second;
    }
    const auto it2 = mapInfo.find((*it).second);
    if (it2 != mapInfo.end()) {
        return &(*it2).second;
    }
    return nullptr;
}
 
AddrInfo *AddrManImpl::Create(const CAddress &addr, const CNetAddr &addrSource,
                              int *pnId) {
    AssertLockHeld(cs);
 
    int nId = nIdCount++;
    mapInfo[nId] = AddrInfo(addr, addrSource);
    mapAddr[addr] = nId;
    mapInfo[nId].nRandomPos = vRandom.size();
    vRandom.push_back(nId);
    if (pnId) {
        *pnId = nId;
    }
    return &mapInfo[nId];
}
 
void AddrManImpl::SwapRandom(unsigned int nRndPos1,
                             unsigned int nRndPos2) const {
    AssertLockHeld(cs);
 
    if (nRndPos1 == nRndPos2) {
        return;
    }
 
    assert(nRndPos1 < vRandom.size() && nRndPos2 < vRandom.size());
 
    int nId1 = vRandom[nRndPos1];
    int nId2 = vRandom[nRndPos2];
 
    const auto it_1{mapInfo.find(nId1)};
    const auto it_2{mapInfo.find(nId2)};
    assert(it_1 != mapInfo.end());
    assert(it_2 != mapInfo.end());
 
    it_1->second.nRandomPos = nRndPos2;
    it_2->second.nRandomPos = nRndPos1;
 
    vRandom[nRndPos1] = nId2;
    vRandom[nRndPos2] = nId1;
}
 
void AddrManImpl::Delete(int nId) {
    AssertLockHeld(cs);
 
    assert(mapInfo.count(nId) != 0);
    AddrInfo &info = mapInfo[nId];
    assert(!info.fInTried);
    assert(info.nRefCount == 0);
 
    SwapRandom(info.nRandomPos, vRandom.size() - 1);
    vRandom.pop_back();
    mapAddr.erase(info);
    mapInfo.erase(nId);
    nNew--;
}
 
void AddrManImpl::ClearNew(int nUBucket, int nUBucketPos) {
    AssertLockHeld(cs);
 
    // if there is an entry in the specified bucket, delete it.
    if (vvNew[nUBucket][nUBucketPos] != -1) {
        int nIdDelete = vvNew[nUBucket][nUBucketPos];
        AddrInfo &infoDelete = mapInfo[nIdDelete];
        assert(infoDelete.nRefCount > 0);
        infoDelete.nRefCount--;
        vvNew[nUBucket][nUBucketPos] = -1;
        LogPrint(BCLog::ADDRMAN, "Removed %s from new[%i][%i]\n",
                 infoDelete.ToString(), nUBucket, nUBucketPos);
        if (infoDelete.nRefCount == 0) {
            Delete(nIdDelete);
        }
    }
}
 
void AddrManImpl::MakeTried(AddrInfo &info, int nId) {
    AssertLockHeld(cs);
 
    // remove the entry from all new buckets
    const int start_bucket{info.GetNewBucket(nKey, m_asmap)};
    for (int n = 0; n < ADDRMAN_NEW_BUCKET_COUNT; ++n) {
        const int bucket{(start_bucket + n) % ADDRMAN_NEW_BUCKET_COUNT};
        const int pos{info.GetBucketPosition(nKey, true, bucket)};
        if (vvNew[bucket][pos] == nId) {
            vvNew[bucket][pos] = -1;
            info.nRefCount--;
            if (info.nRefCount == 0) {
                break;
            }
        }
    }
    nNew--;
 
    assert(info.nRefCount == 0);
 
    // which tried bucket to move the entry to
    int nKBucket = info.GetTriedBucket(nKey, m_asmap);
    int nKBucketPos = info.GetBucketPosition(nKey, false, nKBucket);
 
    // first make space to add it (the existing tried entry there is moved to
    // new, deleting whatever is there).
    if (vvTried[nKBucket][nKBucketPos] != -1) {
        // find an item to evict
        int nIdEvict = vvTried[nKBucket][nKBucketPos];
        assert(mapInfo.count(nIdEvict) == 1);
        AddrInfo &infoOld = mapInfo[nIdEvict];
 
        // Remove the to-be-evicted item from the tried set.
        infoOld.fInTried = false;
        vvTried[nKBucket][nKBucketPos] = -1;
        nTried--;
 
        // find which new bucket it belongs to
        int nUBucket = infoOld.GetNewBucket(nKey, m_asmap);
        int nUBucketPos = infoOld.GetBucketPosition(nKey, true, nUBucket);
        ClearNew(nUBucket, nUBucketPos);
        assert(vvNew[nUBucket][nUBucketPos] == -1);
 
        // Enter it into the new set again.
        infoOld.nRefCount = 1;
        vvNew[nUBucket][nUBucketPos] = nIdEvict;
        nNew++;
        LogPrint(BCLog::ADDRMAN,
                 "Moved %s from tried[%i][%i] to new[%i][%i] to make space\n",
                 infoOld.ToString(), nKBucket, nKBucketPos, nUBucket,
                 nUBucketPos);
    }
    assert(vvTried[nKBucket][nKBucketPos] == -1);
 
    vvTried[nKBucket][nKBucketPos] = nId;
    nTried++;
    info.fInTried = true;
}
 
bool AddrManImpl::AddSingle(const CAddress &addr, const CNetAddr &source,
                            std::chrono::seconds time_penalty) {
    AssertLockHeld(cs);
 
    if (!addr.IsRoutable()) {
        return false;
    }
 
    int nId;
    AddrInfo *pinfo = Find(addr, &nId);
 
    // Do not set a penalty for a source's self-announcement
    if (addr == source) {
        time_penalty = 0s;
    }
 
    if (pinfo) {
        // periodically update nTime
        const bool currently_online{AdjustedTime() - addr.nTime < 24h};
        const auto update_interval{currently_online ? 1h : 24h};
        if (pinfo->nTime < addr.nTime - update_interval - time_penalty) {
            pinfo->nTime = std::max(NodeSeconds{0s}, addr.nTime - time_penalty);
        }
 
        // add services
        pinfo->nServices = ServiceFlags(pinfo->nServices | addr.nServices);
 
        // do not update if no new information is present
        if (addr.nTime <= pinfo->nTime) {
            return false;
        }
 
        // do not update if the entry was already in the "tried" table
        if (pinfo->fInTried) {
            return false;
        }
 
        // do not update if the max reference count is reached
        if (pinfo->nRefCount == ADDRMAN_NEW_BUCKETS_PER_ADDRESS) {
            return false;
        }
 
        // stochastic test: previous nRefCount == N: 2^N times harder to
        // increase it
        int nFactor = 1;
        for (int n = 0; n < pinfo->nRefCount; n++) {
            nFactor *= 2;
        }
 
        if (nFactor > 1 && (insecure_rand.randrange(nFactor) != 0)) {
            return false;
        }
    } else {
        pinfo = Create(addr, source, &nId);
        pinfo->nTime = std::max(NodeSeconds{0s}, pinfo->nTime - time_penalty);
        nNew++;
    }
 
    int nUBucket = pinfo->GetNewBucket(nKey, source, m_asmap);
    int nUBucketPos = pinfo->GetBucketPosition(nKey, true, nUBucket);
    bool fInsert = vvNew[nUBucket][nUBucketPos] == -1;
    if (vvNew[nUBucket][nUBucketPos] != nId) {
        if (!fInsert) {
            AddrInfo &infoExisting = mapInfo[vvNew[nUBucket][nUBucketPos]];
            if (infoExisting.IsTerrible() ||
                (infoExisting.nRefCount > 1 && pinfo->nRefCount == 0)) {
                // Overwrite the existing new table entry.
                fInsert = true;
            }
        }
        if (fInsert) {
            ClearNew(nUBucket, nUBucketPos);
            pinfo->nRefCount++;
            vvNew[nUBucket][nUBucketPos] = nId;
            LogPrint(BCLog::ADDRMAN, "Added %s mapped to AS%i to new[%i][%i]\n",
                     addr.ToString(), addr.GetMappedAS(m_asmap), nUBucket,
                     nUBucketPos);
        } else if (pinfo->nRefCount == 0) {
            Delete(nId);
        }
    }
    return fInsert;
}
 
void AddrManImpl::Good_(const CService &addr, bool test_before_evict,
                        NodeSeconds time) {
    AssertLockHeld(cs);
 
    int nId;
 
    m_last_good = time;
 
    AddrInfo *pinfo = Find(addr, &nId);
 
    // if not found, bail out
    if (!pinfo) {
        return;
    }
 
    AddrInfo &info = *pinfo;
 
    // update info
    info.m_last_success = time;
    info.m_last_try = time;
    info.nAttempts = 0;
    // nTime is not updated here, to avoid leaking information about
    // currently-connected peers.
 
    // if it is already in the tried set, don't do anything else
    if (info.fInTried) {
        return;
    }
 
    // if it is not in new, something bad happened
    if (!Assume(info.nRefCount > 0)) {
        return;
    }
 
    // which tried bucket to move the entry to
    int tried_bucket = info.GetTriedBucket(nKey, m_asmap);
    int tried_bucket_pos = info.GetBucketPosition(nKey, false, tried_bucket);
 
    // Will moving this address into tried evict another entry?
    if (test_before_evict && (vvTried[tried_bucket][tried_bucket_pos] != -1)) {
        if (m_tried_collisions.size() < ADDRMAN_SET_TRIED_COLLISION_SIZE) {
            m_tried_collisions.insert(nId);
        }
        // Output the entry we'd be colliding with, for debugging purposes
        auto colliding_entry =
            mapInfo.find(vvTried[tried_bucket][tried_bucket_pos]);
        LogPrint(BCLog::ADDRMAN,
                 "Collision with %s while attempting to move %s to tried "
                 "table. Collisions=%d\n",
                 colliding_entry != mapInfo.end()
                     ? colliding_entry->second.ToString()
                     : "",
                 addr.ToString(), m_tried_collisions.size());
    } else {
        // move nId to the tried tables
        MakeTried(info, nId);
        LogPrint(BCLog::ADDRMAN, "Moved %s mapped to AS%i to tried[%i][%i]\n",
                 addr.ToString(), addr.GetMappedAS(m_asmap), tried_bucket,
                 tried_bucket_pos);
    }
}
 
bool AddrManImpl::Add_(const std::vector<CAddress> &vAddr,
                       const CNetAddr &source,
                       std::chrono::seconds time_penalty) {
    int added{0};
    for (std::vector<CAddress>::const_iterator it = vAddr.begin();
         it != vAddr.end(); it++) {
        added += AddSingle(*it, source, time_penalty) ? 1 : 0;
    }
    if (added > 0) {
        LogPrint(BCLog::ADDRMAN,
                 "Added %i addresses (of %i) from %s: %i tried, %i new\n",
                 added, vAddr.size(), source.ToString(), nTried, nNew);
    }
    return added > 0;
}
 
void AddrManImpl::Attempt_(const CService &addr, bool fCountFailure,
                           NodeSeconds time) {
    AssertLockHeld(cs);
 
    AddrInfo *pinfo = Find(addr);
 
    // if not found, bail out
    if (!pinfo) {
        return;
    }
 
    AddrInfo &info = *pinfo;
 
    // update info
    info.m_last_try = time;
    if (fCountFailure && info.m_last_count_attempt < m_last_good) {
        info.m_last_count_attempt = time;
        info.nAttempts++;
    }
}
 
std::pair<CAddress, NodeSeconds> AddrManImpl::Select_(bool newOnly) const {
    AssertLockHeld(cs);
 
    if (vRandom.empty()) {
        return {};
    }
 
    if (newOnly && nNew == 0) {
        return {};
    }
 
    // Use a 50% chance for choosing between tried and new table entries.
    if (!newOnly &&
        (nTried > 0 && (nNew == 0 || insecure_rand.randbool() == 0))) {
        // use a tried node
        double fChanceFactor = 1.0;
        while (1) {
            // Pick a tried bucket, and an initial position in that bucket.
            int nKBucket = insecure_rand.randrange(ADDRMAN_TRIED_BUCKET_COUNT);
            int nKBucketPos = insecure_rand.randrange(ADDRMAN_BUCKET_SIZE);
            // Iterate over the positions of that bucket, starting at the
            // initial one, and looping around.
            int i;
            for (i = 0; i < ADDRMAN_BUCKET_SIZE; ++i) {
                if (vvTried[nKBucket]
                           [(nKBucketPos + i) % ADDRMAN_BUCKET_SIZE] != -1) {
                    break;
                }
            }
            // If the bucket is entirely empty, start over with a (likely)
            // different one.
            if (i == ADDRMAN_BUCKET_SIZE) {
                continue;
            }
            // Find the entry to return.
            int nId =
                vvTried[nKBucket][(nKBucketPos + i) % ADDRMAN_BUCKET_SIZE];
            const auto it_found{mapInfo.find(nId)};
            assert(it_found != mapInfo.end());
            const AddrInfo &info{it_found->second};
            // With probability GetChance() * fChanceFactor, return the entry.
            if (insecure_rand.randbits(30) <
                fChanceFactor * info.GetChance() * (1 << 30)) {
                LogPrint(BCLog::ADDRMAN, "Selected %s from tried\n",
                         info.ToString());
                return {info, info.m_last_try};
            }
            // Otherwise start over with a (likely) different bucket, and
            // increased chance factor.
            fChanceFactor *= 1.2;
        }
    } else {
        // use a new node
        double fChanceFactor = 1.0;
        while (1) {
            // Pick a new bucket, and an initial position in that bucket.
            int nUBucket = insecure_rand.randrange(ADDRMAN_NEW_BUCKET_COUNT);
            int nUBucketPos = insecure_rand.randrange(ADDRMAN_BUCKET_SIZE);
            // Iterate over the positions of that bucket, starting at the
            // initial one, and looping around.
            int i;
            for (i = 0; i < ADDRMAN_BUCKET_SIZE; ++i) {
                if (vvNew[nUBucket][(nUBucketPos + i) % ADDRMAN_BUCKET_SIZE] !=
                    -1) {
                    break;
                }
            }
            // If the bucket is entirely empty, start over with a (likely)
            // different one.
            if (i == ADDRMAN_BUCKET_SIZE) {
                continue;
            }
            // Find the entry to return.
            int nId = vvNew[nUBucket][(nUBucketPos + i) % ADDRMAN_BUCKET_SIZE];
            const auto it_found{mapInfo.find(nId)};
            assert(it_found != mapInfo.end());
            const AddrInfo &info{it_found->second};
            // With probability GetChance() * fChanceFactor, return the entry.
            if (insecure_rand.randbits(30) <
                fChanceFactor * info.GetChance() * (1 << 30)) {
                LogPrint(BCLog::ADDRMAN, "Selected %s from new\n",
                         info.ToString());
                return {info, info.m_last_try};
            }
            // Otherwise start over with a (likely) different bucket, and
            // increased chance factor.
            fChanceFactor *= 1.2;
        }
    }
}
 
std::vector<CAddress>
AddrManImpl::GetAddr_(size_t max_addresses, size_t max_pct,
                      std::optional<Network> network) const {
    AssertLockHeld(cs);
 
    size_t nNodes = vRandom.size();
    if (max_pct != 0) {
        nNodes = max_pct * nNodes / 100;
    }
    if (max_addresses != 0) {
        nNodes = std::min(nNodes, max_addresses);
    }
 
    // gather a list of random nodes, skipping those of low quality
    const auto now{AdjustedTime()};
    std::vector<CAddress> addresses;
    for (unsigned int n = 0; n < vRandom.size(); n++) {
        if (addresses.size() >= nNodes) {
            break;
        }
 
        int nRndPos = insecure_rand.randrange(vRandom.size() - n) + n;
        SwapRandom(n, nRndPos);
        const auto it{mapInfo.find(vRandom[n])};
        assert(it != mapInfo.end());
 
        const AddrInfo &ai{it->second};
 
        // Filter by network (optional)
        if (network != std::nullopt && ai.GetNetClass() != network) {
            continue;
        }
 
        // Filter for quality
        if (ai.IsTerrible(now)) {
            continue;
        }
 
        addresses.push_back(ai);
    }
    LogPrint(BCLog::ADDRMAN, "GetAddr returned %d random addresses\n",
             addresses.size());
    return addresses;
}
 
void AddrManImpl::Connected_(const CService &addr, NodeSeconds time) {
    AssertLockHeld(cs);
 
    AddrInfo *pinfo = Find(addr);
 
    // if not found, bail out
    if (!pinfo) {
        return;
    }
 
    AddrInfo &info = *pinfo;
 
    // update info
    const auto update_interval{20min};
    if (time - info.nTime > update_interval) {
        info.nTime = time;
    }
}
 
void AddrManImpl::SetServices_(const CService &addr, ServiceFlags nServices) {
    AssertLockHeld(cs);
 
    AddrInfo *pinfo = Find(addr);
 
    // if not found, bail out
    if (!pinfo) {
        return;
    }
 
    AddrInfo &info = *pinfo;
 
    // update info
    info.nServices = nServices;
}
 
void AddrManImpl::ResolveCollisions_() {
    AssertLockHeld(cs);
 
    const auto current_time{AdjustedTime()};
 
    for (std::set<int>::iterator it = m_tried_collisions.begin();
         it != m_tried_collisions.end();) {
        int id_new = *it;
 
        bool erase_collision = false;
 
        // If id_new not found in mapInfo remove it from
        // m_tried_collisions.
        auto id_new_it = mapInfo.find(id_new);
        if (id_new_it == mapInfo.end()) {
            erase_collision = true;
        } else {
            AddrInfo &info_new = mapInfo[id_new];
 
            // Which tried bucket to move the entry to.
            int tried_bucket = info_new.GetTriedBucket(nKey, m_asmap);
            int tried_bucket_pos =
                info_new.GetBucketPosition(nKey, false, tried_bucket);
            if (!info_new.IsValid()) {
                // id_new may no longer map to a valid address
                erase_collision = true;
            } else if (vvTried[tried_bucket][tried_bucket_pos] != -1) {
                // The position in the tried bucket is not empty
 
                // Get the to-be-evicted address that is being tested
                int id_old = vvTried[tried_bucket][tried_bucket_pos];
                AddrInfo &info_old = mapInfo[id_old];
 
                // Has successfully connected in last X hours
                if (current_time - info_old.m_last_success <
                    ADDRMAN_REPLACEMENT) {
                    erase_collision = true;
                } else if (current_time - info_old.m_last_try <
                           ADDRMAN_REPLACEMENT) {
                    // attempted to connect and failed in last X hours
 
                    // Give address at least 60 seconds to successfully
                    // connect
                    if (current_time - info_old.m_last_try > 60s) {
                        LogPrint(BCLog::ADDRMAN,
                                 "Replacing %s with %s in tried table\n",
                                 info_old.ToString(), info_new.ToString());
 
                        // Replaces an existing address already in the
                        // tried table with the new address
                        Good_(info_new, false, current_time);
                        erase_collision = true;
                    }
                } else if (current_time - info_new.m_last_success >
                           ADDRMAN_TEST_WINDOW) {
                    // If the collision hasn't resolved in some
                    // reasonable amount of time, just evict the old
                    // entry -- we must not be able to connect to it for
                    // some reason.
                    LogPrint(BCLog::ADDRMAN,
                             "Unable to test; replacing %s with %s in tried "
                             "table anyway\n",
                             info_old.ToString(), info_new.ToString());
                    Good_(info_new, false, current_time);
                    erase_collision = true;
                }
            } else {
                // Collision is not actually a collision anymore
                Good_(info_new, false, current_time);
                erase_collision = true;
            }
        }
 
        if (erase_collision) {
            m_tried_collisions.erase(it++);
        } else {
            it++;
        }
    }
}
 
std::pair<CAddress, NodeSeconds> AddrManImpl::SelectTriedCollision_() {
    AssertLockHeld(cs);
 
    if (m_tried_collisions.size() == 0) {
        return {};
    }
 
    std::set<int>::iterator it = m_tried_collisions.begin();
 
    // Selects a random element from m_tried_collisions
    std::advance(it, insecure_rand.randrange(m_tried_collisions.size()));
    int id_new = *it;
 
    // If id_new not found in mapInfo remove it from m_tried_collisions.
    auto id_new_it = mapInfo.find(id_new);
    if (id_new_it == mapInfo.end()) {
        m_tried_collisions.erase(it);
        return {};
    }
 
    const AddrInfo &newInfo = id_new_it->second;
 
    // which tried bucket to move the entry to
    int tried_bucket = newInfo.GetTriedBucket(nKey, m_asmap);
    int tried_bucket_pos = newInfo.GetBucketPosition(nKey, false, tried_bucket);
 
    const AddrInfo &info_old = mapInfo[vvTried[tried_bucket][tried_bucket_pos]];
    return {info_old, info_old.m_last_try};
}
 
void AddrManImpl::Check() const {
    AssertLockHeld(cs);
 
    // Run consistency checks 1 in m_consistency_check_ratio times if enabled
    if (m_consistency_check_ratio == 0) {
        return;
    }
    if (insecure_rand.randrange(m_consistency_check_ratio) >= 1) {
        return;
    }
 
    const int err{CheckAddrman()};
    if (err) {
        LogPrintf("ADDRMAN CONSISTENCY CHECK FAILED!!! err=%i\n", err);
        assert(false);
    }
}
 
int AddrManImpl::CheckAddrman() const {
    AssertLockHeld(cs);
 
    LOG_TIME_MILLIS_WITH_CATEGORY_MSG_ONCE(
        strprintf("new %i, tried %i, total %u", nNew, nTried, vRandom.size()),
        BCLog::ADDRMAN);
 
    std::unordered_set<int> setTried;
    std::unordered_map<int, int> mapNew;
 
    if (vRandom.size() != size_t(nTried + nNew)) {
        return -7;
    }
 
    for (const auto &entry : mapInfo) {
        int n = entry.first;
        const AddrInfo &info = entry.second;
        if (info.fInTried) {
            if (!TicksSinceEpoch<std::chrono::seconds>(info.m_last_success)) {
                return -1;
            }
            if (info.nRefCount) {
                return -2;
            }
            setTried.insert(n);
        } else {
            if (info.nRefCount < 0 ||
                info.nRefCount > ADDRMAN_NEW_BUCKETS_PER_ADDRESS) {
                return -3;
            }
            if (!info.nRefCount) {
                return -4;
            }
            mapNew[n] = info.nRefCount;
        }
        const auto it{mapAddr.find(info)};
        if (it == mapAddr.end() || it->second != n) {
            return -5;
        }
        if (info.nRandomPos < 0 || size_t(info.nRandomPos) >= vRandom.size() ||
            vRandom[info.nRandomPos] != n) {
            return -14;
        }
        if (info.m_last_try < NodeSeconds{0s}) {
            return -6;
        }
        if (info.m_last_success < NodeSeconds{0s}) {
            return -8;
        }
    }
 
    if (setTried.size() != size_t(nTried)) {
        return -9;
    }
    if (mapNew.size() != size_t(nNew)) {
        return -10;
    }
 
    for (int n = 0; n < ADDRMAN_TRIED_BUCKET_COUNT; n++) {
        for (int i = 0; i < ADDRMAN_BUCKET_SIZE; i++) {
            if (vvTried[n][i] != -1) {
                if (!setTried.count(vvTried[n][i])) {
                    return -11;
                }
                const auto it{mapInfo.find(vvTried[n][i])};
                if (it == mapInfo.end() ||
                    it->second.GetTriedBucket(nKey, m_asmap) != n) {
                    return -17;
                }
                if (it->second.GetBucketPosition(nKey, false, n) != i) {
                    return -18;
                }
                setTried.erase(vvTried[n][i]);
            }
        }
    }
 
    for (int n = 0; n < ADDRMAN_NEW_BUCKET_COUNT; n++) {
        for (int i = 0; i < ADDRMAN_BUCKET_SIZE; i++) {
            if (vvNew[n][i] != -1) {
                if (!mapNew.count(vvNew[n][i])) {
                    return -12;
                }
                const auto it{mapInfo.find(vvNew[n][i])};
                if (it == mapInfo.end() ||
                    it->second.GetBucketPosition(nKey, true, n) != i) {
                    return -19;
                }
                if (--mapNew[vvNew[n][i]] == 0) {
                    mapNew.erase(vvNew[n][i]);
                }
            }
        }
    }
 
    if (setTried.size()) {
        return -13;
    }
    if (mapNew.size()) {
        return -15;
    }
    if (nKey.IsNull()) {
        return -16;
    }
 
    return 0;
}
 
size_t AddrManImpl::size() const {
    // TODO: Cache this in an atomic to avoid this overhead
    LOCK(cs);
    return vRandom.size();
}
 
bool AddrManImpl::Add(const std::vector<CAddress> &vAddr,
                      const CNetAddr &source,
                      std::chrono::seconds time_penalty) {
    LOCK(cs);
    Check();
    auto ret = Add_(vAddr, source, time_penalty);
    Check();
    return ret;
}
 
void AddrManImpl::Good(const CService &addr, bool test_before_evict,
                       NodeSeconds time) {
    LOCK(cs);
    Check();
    Good_(addr, test_before_evict, time);
    Check();
}
 
void AddrManImpl::Attempt(const CService &addr, bool fCountFailure,
                          NodeSeconds time) {
    LOCK(cs);
    Check();
    Attempt_(addr, fCountFailure, time);
    Check();
}
 
void AddrManImpl::ResolveCollisions() {
    LOCK(cs);
    Check();
    ResolveCollisions_();
    Check();
}
 
std::pair<CAddress, NodeSeconds> AddrManImpl::SelectTriedCollision() {
    LOCK(cs);
    Check();
    const auto ret = SelectTriedCollision_();
    Check();
    return ret;
}
 
std::pair<CAddress, NodeSeconds> AddrManImpl::Select(bool newOnly) const {
    LOCK(cs);
    Check();
    const auto addrRet = Select_(newOnly);
    Check();
    return addrRet;
}
 
std::vector<CAddress>
AddrManImpl::GetAddr(size_t max_addresses, size_t max_pct,
                     std::optional<Network> network) const {
    LOCK(cs);
    Check();
    const auto addresses = GetAddr_(max_addresses, max_pct, network);
    Check();
    return addresses;
}
 
void AddrManImpl::Connected(const CService &addr, NodeSeconds time) {
    LOCK(cs);
    Check();
    Connected_(addr, time);
    Check();
}
 
void AddrManImpl::SetServices(const CService &addr, ServiceFlags nServices) {
    LOCK(cs);
    Check();
    SetServices_(addr, nServices);
    Check();
}
 
const std::vector<bool> &AddrManImpl::GetAsmap() const {
    return m_asmap;
}
 
void AddrManImpl::Clear() {
    LOCK(cs);
    std::vector<int>().swap(vRandom);
 
    if (deterministic) {
        nKey = uint256{1};
        insecure_rand = FastRandomContext(true);
    } else {
        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;
    // Initially at 1 so that "never" is strictly worse.
    m_last_good = NodeSeconds{1s};
    mapInfo.clear();
    mapAddr.clear();
}
 
void AddrManImpl::MakeDeterministic() {
    deterministic = true;
    Clear();
}
 
AddrMan::AddrMan(std::vector<bool> asmap, int32_t consistency_check_ratio)
    : m_impl(std::make_unique<AddrManImpl>(std::move(asmap),
                                           consistency_check_ratio)) {
    Clear();
}
 
AddrMan::~AddrMan() = default;
 
template <typename Stream> void AddrMan::Serialize(Stream &s_) const {
    m_impl->Serialize<Stream>(s_);
}
 
template <typename Stream> void AddrMan::Unserialize(Stream &s_) {
    m_impl->Unserialize<Stream>(s_);
}
 
// explicit instantiation
template void AddrMan::Serialize(CHashWriter &s) const;
template void AddrMan::Serialize(CAutoFile &s) const;
template void AddrMan::Serialize(CDataStream &s) const;
template void AddrMan::Unserialize(CAutoFile &s);
template void AddrMan::Unserialize(CHashVerifier<CAutoFile> &s);
template void AddrMan::Unserialize(CDataStream &s);
template void AddrMan::Unserialize(CHashVerifier<CDataStream> &s);
 
size_t AddrMan::size() const {
    return m_impl->size();
}
 
bool AddrMan::Add(const std::vector<CAddress> &vAddr, const CNetAddr &source,
                  std::chrono::seconds time_penalty) {
    return m_impl->Add(vAddr, source, time_penalty);
}
 
void AddrMan::Good(const CService &addr, bool test_before_evict,
                   NodeSeconds time) {
    m_impl->Good(addr, test_before_evict, time);
}
 
void AddrMan::Attempt(const CService &addr, bool fCountFailure,
                      NodeSeconds time) {
    m_impl->Attempt(addr, fCountFailure, time);
}
 
void AddrMan::ResolveCollisions() {
    m_impl->ResolveCollisions();
}
 
std::pair<CAddress, NodeSeconds> AddrMan::SelectTriedCollision() {
    return m_impl->SelectTriedCollision();
}
 
std::pair<CAddress, NodeSeconds> AddrMan::Select(bool newOnly) const {
    return m_impl->Select(newOnly);
}
 
std::vector<CAddress> AddrMan::GetAddr(size_t max_addresses, size_t max_pct,
                                       std::optional<Network> network) const {
    return m_impl->GetAddr(max_addresses, max_pct, network);
}
 
void AddrMan::Connected(const CService &addr, NodeSeconds time) {
    m_impl->Connected(addr, time);
}
 
void AddrMan::SetServices(const CService &addr, ServiceFlags nServices) {
    m_impl->SetServices(addr, nServices);
}
 
const std::vector<bool> &AddrMan::GetAsmap() const {
    return m_impl->GetAsmap();
}
 
void AddrMan::Clear() {
    return m_impl->Clear();
}
 
void AddrMan::MakeDeterministic() {
    return m_impl->MakeDeterministic();
}