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Expire old entries from the in-flight tx map

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If a peer hasn't responded to a getdata request, eventually time out the request
and remove it from the in-flight data structures.  This is to prevent any bugs in
our handling of those in-flight data structures from filling up the in-flight
map and preventing us from requesting more transactions (such as the NOTFOUND
bug, fixed in a previous commit).

Co-authored-by: Anthony Towns <aj@erisian.com.au>
This commit is contained in:
Suhas Daftuar 2019-04-16 15:48:55 -04:00
parent e32e08407e
commit f635a3ba11
1 changed files with 32 additions and 6 deletions
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38
src/net_processing.cpp
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@ -70,11 +70,13 @@ 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 from inbound peers */
static constexpr int64_t INBOUND_PEER_TX_DELAY = 2 * 1000000;
static constexpr int64_t INBOUND_PEER_TX_DELAY = 2 * 1000000; // 2 seconds
/** How long to wait (in microseconds) before downloading a transaction from an additional peer */
static constexpr int64_t GETDATA_TX_INTERVAL = 60 * 1000000;
static constexpr int64_t GETDATA_TX_INTERVAL = 60 * 1000000; // 1 minute
/** Maximum delay (in microseconds) for transaction requests to avoid biasing some peers over others. */
static constexpr int64_t MAX_GETDATA_RANDOM_DELAY = 2 * 1000000;
static constexpr int64_t MAX_GETDATA_RANDOM_DELAY = 2 * 1000000; // 2 seconds
/** How long to wait (in microseconds) before expiring an in-flight getdata request to a peer */
static constexpr int64_t TX_EXPIRY_INTERVAL = 10 * GETDATA_TX_INTERVAL;
static_assert(INBOUND_PEER_TX_DELAY >= MAX_GETDATA_RANDOM_DELAY,
"To preserve security, MAX_GETDATA_RANDOM_DELAY should not exceed INBOUND_PEER_DELAY");
/** Limit to avoid sending big packets. Not used in processing incoming GETDATA for compatibility */
@ -345,8 +347,11 @@ struct CNodeState {
//! Store all the transactions a peer has recently announced
std::set<uint256> m_tx_announced;
//! Store transactions which were requested by us
std::set<uint256> m_tx_in_flight;
//! Store transactions which were requested by us, with timestamp
std::map<uint256, int64_t> m_tx_in_flight;
//! Periodically check for stuck getdata requests
int64_t m_check_expiry_timer{0};
};
TxDownloadState m_tx_download;
@ -3939,6 +3944,27 @@ bool PeerLogicValidation::SendMessages(CNode* pto)
//
// Message: getdata (non-blocks)
//
// For robustness, expire old requests after a long timeout, so that
// we can resume downloading transactions from a peer even if they
// were unresponsive in the past.
// Eventually we should consider disconnecting peers, but this is
// conservative.
if (state.m_tx_download.m_check_expiry_timer <= nNow) {
for (auto it=state.m_tx_download.m_tx_in_flight.begin(); it != state.m_tx_download.m_tx_in_flight.end();) {
if (it->second <= nNow - TX_EXPIRY_INTERVAL) {
LogPrint(BCLog::NET, "timeout of inflight tx %s from peer=%d\n", it->first.ToString(), pto->GetId());
state.m_tx_download.m_tx_announced.erase(it->first);
state.m_tx_download.m_tx_in_flight.erase(it++);
} else {
++it;
}
}
// On average, we do this check every TX_EXPIRY_INTERVAL. Randomize
// so that we're not doing this for all peers at the same time.
state.m_tx_download.m_check_expiry_timer = nNow + TX_EXPIRY_INTERVAL/2 + GetRand(TX_EXPIRY_INTERVAL);
}
auto& tx_process_time = state.m_tx_download.m_tx_process_time;
while (!tx_process_time.empty() && tx_process_time.begin()->first <= nNow && state.m_tx_download.m_tx_in_flight.size() < MAX_PEER_TX_IN_FLIGHT) {
const uint256& txid = tx_process_time.begin()->second;
@ -3955,7 +3981,7 @@ bool PeerLogicValidation::SendMessages(CNode* pto)
vGetData.clear();
}
UpdateTxRequestTime(inv.hash, nNow);
state.m_tx_download.m_tx_in_flight.insert(inv.hash);
state.m_tx_download.m_tx_in_flight.emplace(inv.hash, nNow);
} else {
// This transaction is in flight from someone else; queue
// up processing to happen after the download times out