From c1d6a1003d601ec4ff7d9507563254b29868182f Mon Sep 17 00:00:00 2001 From: Suhas Daftuar Date: Fri, 31 Jan 2020 11:23:27 -0500 Subject: Delay getdata requests from peers using txid-based relay Using both txid and wtxid-based relay with peers means that we could sometimes download the same transaction twice, if announced via two different hashes from different peers. Use a heuristic of delaying txid-peer-getdata requests by 2 seconds, if we have at least one wtxid-based peer. --- src/net_processing.cpp | 26 +++++++++++++++++++++++--- test/functional/p2p_tx_download.py | 3 ++- 2 files changed, 25 insertions(+), 4 deletions(-) diff --git a/src/net_processing.cpp b/src/net_processing.cpp index 835095f4d0..0527bd2022 100644 --- a/src/net_processing.cpp +++ b/src/net_processing.cpp @@ -68,6 +68,8 @@ static constexpr int HISTORICAL_BLOCK_AGE = 7 * 24 * 60 * 60; static constexpr int32_t MAX_PEER_TX_IN_FLIGHT = 100; /** Maximum number of announced transactions from a peer */ static constexpr int32_t MAX_PEER_TX_ANNOUNCEMENTS = 2 * MAX_INV_SZ; +/** How many microseconds to delay requesting transactions via txids, if we have wtxid-relaying peers */ +static constexpr std::chrono::microseconds TXID_RELAY_DELAY{std::chrono::seconds{2}}; /** How many microseconds to delay requesting transactions from inbound peers */ static constexpr std::chrono::microseconds INBOUND_PEER_TX_DELAY{std::chrono::seconds{2}}; /** How long to wait (in microseconds) before downloading a transaction from an additional peer */ @@ -174,6 +176,9 @@ namespace { /** Number of peers from which we're downloading blocks. */ int nPeersWithValidatedDownloads GUARDED_BY(cs_main) = 0; + /** Number of peers with wtxid relay. */ + int g_wtxid_relay_peers GUARDED_BY(cs_main) = 0; + /** Number of outbound peers with m_chain_sync.m_protect. */ int g_outbound_peers_with_protect_from_disconnect GUARDED_BY(cs_main) = 0; @@ -715,7 +720,7 @@ void UpdateTxRequestTime(const uint256& txid, std::chrono::microseconds request_ } } -std::chrono::microseconds CalculateTxGetDataTime(const uint256& txid, std::chrono::microseconds current_time, bool use_inbound_delay) EXCLUSIVE_LOCKS_REQUIRED(cs_main) +std::chrono::microseconds CalculateTxGetDataTime(const uint256& txid, std::chrono::microseconds current_time, bool use_inbound_delay, bool use_txid_delay) EXCLUSIVE_LOCKS_REQUIRED(cs_main) { std::chrono::microseconds process_time; const auto last_request_time = GetTxRequestTime(txid); @@ -731,6 +736,9 @@ std::chrono::microseconds CalculateTxGetDataTime(const uint256& txid, std::chron // We delay processing announcements from inbound peers if (use_inbound_delay) process_time += INBOUND_PEER_TX_DELAY; + // We delay processing announcements from peers that use txid-relay (instead of wtxid) + if (use_txid_delay) process_time += TXID_RELAY_DELAY; + return process_time; } @@ -748,7 +756,7 @@ void RequestTx(CNodeState* state, const uint256& txid, std::chrono::microseconds // Calculate the time to try requesting this transaction. Use // fPreferredDownload as a proxy for outbound peers. - const auto process_time = CalculateTxGetDataTime(txid, current_time, !state->fPreferredDownload); + const auto process_time = CalculateTxGetDataTime(txid, current_time, !state->fPreferredDownload, !state->m_wtxid_relay && g_wtxid_relay_peers > 0); peer_download_state.m_tx_process_time.emplace(process_time, txid); } @@ -805,6 +813,8 @@ void PeerLogicValidation::FinalizeNode(NodeId nodeid, bool& fUpdateConnectionTim assert(nPeersWithValidatedDownloads >= 0); g_outbound_peers_with_protect_from_disconnect -= state->m_chain_sync.m_protect; assert(g_outbound_peers_with_protect_from_disconnect >= 0); + g_wtxid_relay_peers -= state->m_wtxid_relay; + assert(g_wtxid_relay_peers >= 0); mapNodeState.erase(nodeid); @@ -814,6 +824,7 @@ void PeerLogicValidation::FinalizeNode(NodeId nodeid, bool& fUpdateConnectionTim assert(nPreferredDownload == 0); assert(nPeersWithValidatedDownloads == 0); assert(g_outbound_peers_with_protect_from_disconnect == 0); + assert(g_wtxid_relay_peers == 0); } LogPrint(BCLog::NET, "Cleared nodestate for peer=%d\n", nodeid); } @@ -2205,6 +2216,7 @@ bool ProcessMessage(CNode* pfrom, const std::string& msg_type, CDataStream& vRec LOCK(cs_main); if (!State(pfrom->GetId())->m_wtxid_relay) { State(pfrom->GetId())->m_wtxid_relay = true; + g_wtxid_relay_peers++; } } return false; @@ -4208,7 +4220,15 @@ bool PeerLogicValidation::SendMessages(CNode* pto) // up processing to happen after the download times out // (with a slight delay for inbound peers, to prefer // requests to outbound peers). - const auto next_process_time = CalculateTxGetDataTime(txid, current_time, !state.fPreferredDownload); + // Don't apply the txid-delay to re-requests of a + // transaction; the heuristic of delaying requests to + // txid-relay peers is to save bandwidth on initial + // announcement of a transaction, and doesn't make sense + // for a followup request if our first peer times out (and + // would open us up to an attacker using inbound + // wtxid-relay to prevent us from requesting transactions + // from outbound txid-relay peers). + const auto next_process_time = CalculateTxGetDataTime(txid, current_time, !state.fPreferredDownload, false); tx_process_time.emplace(next_process_time, txid); } } else { diff --git a/test/functional/p2p_tx_download.py b/test/functional/p2p_tx_download.py index b56dc994e7..c0edeebcee 100755 --- a/test/functional/p2p_tx_download.py +++ b/test/functional/p2p_tx_download.py @@ -44,12 +44,13 @@ class TestP2PConn(P2PInterface): GETDATA_TX_INTERVAL = 60 # seconds MAX_GETDATA_RANDOM_DELAY = 2 # seconds INBOUND_PEER_TX_DELAY = 2 # seconds +TXID_RELAY_DELAY = 2 # seconds MAX_GETDATA_IN_FLIGHT = 100 TX_EXPIRY_INTERVAL = GETDATA_TX_INTERVAL * 10 # Python test constants NUM_INBOUND = 10 -MAX_GETDATA_INBOUND_WAIT = GETDATA_TX_INTERVAL + MAX_GETDATA_RANDOM_DELAY + INBOUND_PEER_TX_DELAY +MAX_GETDATA_INBOUND_WAIT = GETDATA_TX_INTERVAL + MAX_GETDATA_RANDOM_DELAY + INBOUND_PEER_TX_DELAY + TXID_RELAY_DELAY class TxDownloadTest(BitcoinTestFramework): -- cgit v1.2.3