diff options
Diffstat (limited to 'src/net.cpp')
| -rw-r--r-- | src/net.cpp | 44 |
1 files changed, 42 insertions, 2 deletions
diff --git a/src/net.cpp b/src/net.cpp index fe1baf97a3..7cb91f1388 100644 --- a/src/net.cpp +++ b/src/net.cpp @@ -1841,6 +1841,20 @@ int CConnman::GetExtraFullOutboundCount() return std::max(full_outbound_peers - m_max_outbound_full_relay, 0); } +int CConnman::GetExtraBlockRelayCount() +{ + int block_relay_peers = 0; + { + LOCK(cs_vNodes); + for (const CNode* pnode : vNodes) { + if (pnode->fSuccessfullyConnected && !pnode->fDisconnect && pnode->IsBlockOnlyConn()) { + ++block_relay_peers; + } + } + } + return std::max(block_relay_peers - m_max_outbound_block_relay, 0); +} + void CConnman::ThreadOpenConnections(const std::vector<std::string> connect) { // Connect to specific addresses @@ -1869,6 +1883,7 @@ void CConnman::ThreadOpenConnections(const std::vector<std::string> connect) // Minimum time before next feeler connection (in microseconds). int64_t nNextFeeler = PoissonNextSend(nStart*1000*1000, FEELER_INTERVAL); + int64_t nNextExtraBlockRelay = PoissonNextSend(nStart*1000*1000, EXTRA_BLOCK_RELAY_ONLY_PEER_INTERVAL); while (!interruptNet) { ProcessAddrFetch(); @@ -1941,8 +1956,9 @@ void CConnman::ThreadOpenConnections(const std::vector<std::string> connect) // until we hit our block-relay-only peer limit. // GetTryNewOutboundPeer() gets set when a stale tip is detected, so we // try opening an additional OUTBOUND_FULL_RELAY connection. If none of - // these conditions are met, check the nNextFeeler timer to decide if - // we should open a FEELER. + // these conditions are met, check to see if it's time to try an extra + // block-relay-only peer (to confirm our tip is current, see below) or the nNextFeeler + // timer to decide if we should open a FEELER. if (!m_anchors.empty() && (nOutboundBlockRelay < m_max_outbound_block_relay)) { conn_type = ConnectionType::BLOCK_RELAY; @@ -1953,6 +1969,30 @@ void CConnman::ThreadOpenConnections(const std::vector<std::string> connect) conn_type = ConnectionType::BLOCK_RELAY; } else if (GetTryNewOutboundPeer()) { // OUTBOUND_FULL_RELAY + } else if (nTime > nNextExtraBlockRelay && m_start_extra_block_relay_peers) { + // Periodically connect to a peer (using regular outbound selection + // methodology from addrman) and stay connected long enough to sync + // headers, but not much else. + // + // Then disconnect the peer, if we haven't learned anything new. + // + // The idea is to make eclipse attacks very difficult to pull off, + // because every few minutes we're finding a new peer to learn headers + // from. + // + // This is similar to the logic for trying extra outbound (full-relay) + // peers, except: + // - we do this all the time on a poisson timer, rather than just when + // our tip is stale + // - we potentially disconnect our next-youngest block-relay-only peer, if our + // newest block-relay-only peer delivers a block more recently. + // See the eviction logic in net_processing.cpp. + // + // Because we can promote these connections to block-relay-only + // connections, they do not get their own ConnectionType enum + // (similar to how we deal with extra outbound peers). + nNextExtraBlockRelay = PoissonNextSend(nTime, EXTRA_BLOCK_RELAY_ONLY_PEER_INTERVAL); + conn_type = ConnectionType::BLOCK_RELAY; } else if (nTime > nNextFeeler) { nNextFeeler = PoissonNextSend(nTime, FEELER_INTERVAL); conn_type = ConnectionType::FEELER; |