diff --git a/doc/files.md b/doc/files.md index e3f195de43f..65f98e6986c 100644 --- a/doc/files.md +++ b/doc/files.md @@ -50,6 +50,7 @@ Subdirectory | File(s) | Description `indexes/blockfilter/basic/db/` | LevelDB database | Blockfilter index LevelDB database for the basic filtertype; *optional*, used if `-blockfilterindex=basic` `indexes/blockfilter/basic/` | `fltrNNNNN.dat`[\[2\]](#note2) | Blockfilter index filters for the basic filtertype; *optional*, used if `-blockfilterindex=basic` `wallets/` | | [Contains wallets](#multi-wallet-environment); can be specified by `-walletdir` option; if `wallets/` subdirectory does not exist, wallets reside in the [data directory](#data-directory-location) +`./` | `anchors.dat` | Anchor IP address database, created on shutdown and deleted at startup. Anchors are last known outgoing block-relay-only peers that are tried to re-connect to on startup `./` | `banlist.dat` | Stores the IPs/subnets of banned nodes `./` | `bitcoin.conf` | User-defined [configuration settings](bitcoin-conf.md) for `bitcoind` or `bitcoin-qt`. File is not written to by the software and must be created manually. Path can be specified by `-conf` option `./` | `bitcoind.pid` | Stores the process ID (PID) of `bitcoind` or `bitcoin-qt` while running; created at start and deleted on shutdown; can be specified by `-pid` option diff --git a/src/addrdb.cpp b/src/addrdb.cpp index f3e8a19de22..27f22826a9e 100644 --- a/src/addrdb.cpp +++ b/src/addrdb.cpp @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -156,3 +157,22 @@ bool CAddrDB::Read(CAddrMan& addr, CDataStream& ssPeers) } return ret; } + +void DumpAnchors(const fs::path& anchors_db_path, const std::vector& anchors) +{ + LOG_TIME_SECONDS(strprintf("Flush %d outbound block-relay-only peer addresses to anchors.dat", anchors.size())); + SerializeFileDB("anchors", anchors_db_path, anchors); +} + +std::vector ReadAnchors(const fs::path& anchors_db_path) +{ + std::vector anchors; + if (DeserializeFileDB(anchors_db_path, anchors)) { + LogPrintf("Loaded %i addresses from %s\n", anchors.size(), anchors_db_path.filename()); + } else { + anchors.clear(); + } + + fs::remove(anchors_db_path); + return anchors; +} diff --git a/src/addrdb.h b/src/addrdb.h index 8410c3776c4..4ac0e3e1b57 100644 --- a/src/addrdb.h +++ b/src/addrdb.h @@ -11,9 +11,9 @@ #include #include -#include +#include -class CSubNet; +class CAddress; class CAddrMan; class CDataStream; @@ -73,4 +73,20 @@ public: bool Read(banmap_t& banSet); }; +/** + * Dump the anchor IP address database (anchors.dat) + * + * Anchors are last known outgoing block-relay-only peers that are + * tried to re-connect to on startup. + */ +void DumpAnchors(const fs::path& anchors_db_path, const std::vector& anchors); + +/** + * Read the anchor IP address database (anchors.dat) + * + * Deleting anchors.dat is intentional as it avoids renewed peering to anchors after + * an unclean shutdown and thus potential exploitation of the anchor peer policy. + */ +std::vector ReadAnchors(const fs::path& anchors_db_path); + #endif // BITCOIN_ADDRDB_H diff --git a/src/net.cpp b/src/net.cpp index 5db7fc9e730..e8a27c35305 100644 --- a/src/net.cpp +++ b/src/net.cpp @@ -47,6 +47,12 @@ static_assert(MINIUPNPC_API_VERSION >= 10, "miniUPnPc API version >= 10 assumed" #include +/** Maximum number of block-relay-only anchor connections */ +static constexpr size_t MAX_BLOCK_RELAY_ONLY_ANCHORS = 2; +static_assert (MAX_BLOCK_RELAY_ONLY_ANCHORS <= static_cast(MAX_BLOCK_RELAY_ONLY_CONNECTIONS), "MAX_BLOCK_RELAY_ONLY_ANCHORS must not exceed MAX_BLOCK_RELAY_ONLY_CONNECTIONS."); +/** Anchor IP address database file name */ +const char* const ANCHORS_DATABASE_FILENAME = "anchors.dat"; + // How often to dump addresses to peers.dat static constexpr std::chrono::minutes DUMP_PEERS_INTERVAL{15}; @@ -1933,10 +1939,12 @@ void CConnman::ThreadOpenConnections(const std::vector connect) ConnectionType conn_type = ConnectionType::OUTBOUND_FULL_RELAY; int64_t nTime = GetTimeMicros(); + bool anchor = false; bool fFeeler = false; // Determine what type of connection to open. Opening - // OUTBOUND_FULL_RELAY connections gets the highest priority until we + // BLOCK_RELAY connections to addresses from anchors.dat gets the highest + // priority. Then we open OUTBOUND_FULL_RELAY priority until we // meet our full-relay capacity. Then we open BLOCK_RELAY connection // until we hit our block-relay-only peer limit. // GetTryNewOutboundPeer() gets set when a stale tip is detected, so we @@ -1944,7 +1952,10 @@ void CConnman::ThreadOpenConnections(const std::vector connect) // these conditions are met, check the nNextFeeler timer to decide if // we should open a FEELER. - if (nOutboundFullRelay < m_max_outbound_full_relay) { + if (!m_anchors.empty() && (nOutboundBlockRelay < m_max_outbound_block_relay)) { + conn_type = ConnectionType::BLOCK_RELAY; + anchor = true; + } else if (nOutboundFullRelay < m_max_outbound_full_relay) { // OUTBOUND_FULL_RELAY } else if (nOutboundBlockRelay < m_max_outbound_block_relay) { conn_type = ConnectionType::BLOCK_RELAY; @@ -1965,6 +1976,24 @@ void CConnman::ThreadOpenConnections(const std::vector connect) int nTries = 0; while (!interruptNet) { + if (anchor && !m_anchors.empty()) { + const CAddress addr = m_anchors.back(); + m_anchors.pop_back(); + if (!addr.IsValid() || IsLocal(addr) || !IsReachable(addr) || + !HasAllDesirableServiceFlags(addr.nServices) || + setConnected.count(addr.GetGroup(addrman.m_asmap))) continue; + addrConnect = addr; + LogPrint(BCLog::NET, "Trying to make an anchor connection to %s\n", addrConnect.ToString()); + break; + } + + // If we didn't find an appropriate destination after trying 100 addresses fetched from addrman, + // stop this loop, and let the outer loop run again (which sleeps, adds seed nodes, recalculates + // already-connected network ranges, ...) before trying new addrman addresses. + nTries++; + if (nTries > 100) + break; + CAddrInfo addr = addrman.SelectTriedCollision(); // SelectTriedCollision returns an invalid address if it is empty. @@ -1982,13 +2011,6 @@ void CConnman::ThreadOpenConnections(const std::vector connect) break; } - // If we didn't find an appropriate destination after trying 100 addresses fetched from addrman, - // stop this loop, and let the outer loop run again (which sleeps, adds seed nodes, recalculates - // already-connected network ranges, ...) before trying new addrman addresses. - nTries++; - if (nTries > 100) - break; - if (!IsReachable(addr)) continue; @@ -2028,6 +2050,19 @@ void CConnman::ThreadOpenConnections(const std::vector connect) } } +std::vector CConnman::GetCurrentBlockRelayOnlyConns() const +{ + std::vector ret; + LOCK(cs_vNodes); + for (const CNode* pnode : vNodes) { + if (pnode->IsBlockOnlyConn()) { + ret.push_back(pnode->addr); + } + } + + return ret; +} + std::vector CConnman::GetAddedNodeInfo() { std::vector ret; @@ -2427,6 +2462,15 @@ bool CConnman::Start(CScheduler& scheduler, const Options& connOptions) } } + if (m_use_addrman_outgoing) { + // Load addresses from anchors.dat + m_anchors = ReadAnchors(GetDataDir() / ANCHORS_DATABASE_FILENAME); + if (m_anchors.size() > MAX_BLOCK_RELAY_ONLY_ANCHORS) { + m_anchors.resize(MAX_BLOCK_RELAY_ONLY_ANCHORS); + } + LogPrintf("%i block-relay-only anchors will be tried for connections.\n", m_anchors.size()); + } + uiInterface.InitMessage(_("Starting network threads...").translated); fAddressesInitialized = true; @@ -2542,6 +2586,15 @@ void CConnman::StopNodes() if (fAddressesInitialized) { DumpAddresses(); fAddressesInitialized = false; + + if (m_use_addrman_outgoing) { + // Anchor connections are only dumped during clean shutdown. + std::vector anchors_to_dump = GetCurrentBlockRelayOnlyConns(); + if (anchors_to_dump.size() > MAX_BLOCK_RELAY_ONLY_ANCHORS) { + anchors_to_dump.resize(MAX_BLOCK_RELAY_ONLY_ANCHORS); + } + DumpAnchors(GetDataDir() / ANCHORS_DATABASE_FILENAME, anchors_to_dump); + } } // Close sockets diff --git a/src/net.h b/src/net.h index fb5c2bd3287..40eab889a63 100644 --- a/src/net.h +++ b/src/net.h @@ -173,7 +173,9 @@ enum class ConnectionType { * attacks. By not relaying transactions or addresses, these connections * are harder to detect by a third party, thus helping obfuscate the * network topology. We automatically attempt to open - * MAX_BLOCK_RELAY_ONLY_CONNECTIONS using addresses from our AddrMan. + * MAX_BLOCK_RELAY_ONLY_ANCHORS using addresses from our anchors.dat. Then + * addresses from our AddrMan if MAX_BLOCK_RELAY_ONLY_CONNECTIONS + * isn't reached yet. */ BLOCK_RELAY, @@ -460,6 +462,11 @@ private: void RecordBytesRecv(uint64_t bytes); void RecordBytesSent(uint64_t bytes); + /** + * Return vector of current BLOCK_RELAY peers. + */ + std::vector GetCurrentBlockRelayOnlyConns() const; + // Whether the node should be passed out in ForEach* callbacks static bool NodeFullyConnected(const CNode* pnode); @@ -561,6 +568,12 @@ private: /** Pointer to this node's banman. May be nullptr - check existence before dereferencing. */ BanMan* m_banman; + /** + * Addresses that were saved during the previous clean shutdown. We'll + * attempt to make block-relay-only connections to them. + */ + std::vector m_anchors; + /** SipHasher seeds for deterministic randomness */ const uint64_t nSeed0, nSeed1;