mirror of https://github.com/bitcoin/bitcoin
This module is going to be responsible for managing everything related to transaction download, including txrequest, orphan transactions and package relay. It will be responsible for managing usage of the TxOrphanage and instructing PeerManager: - what tx or package-related messages to send to which peer - whether a tx or package-related message is allowed or useful - what transactions are available to try accepting to mempool Future commits will consolidate the interface and re-delegate interactions from PeerManager to TxDownloadManager.pull/30110/head
glozow
3 years ago
parent
5ea335a97f
commit
5f9004e155
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// Copyright (c) 2024 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_NODE_TXDOWNLOADMAN_H
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#define BITCOIN_NODE_TXDOWNLOADMAN_H
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#include <cstdint>
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#include <memory>
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class TxOrphanage;
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class TxRequestTracker;
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class CRollingBloomFilter;
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namespace node {
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class TxDownloadManagerImpl;
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/**
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* Class responsible for deciding what transactions to request and, once
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* downloaded, whether and how to validate them. It is also responsible for
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* deciding what transaction packages to validate and how to resolve orphan
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* transactions. Its data structures include TxRequestTracker for scheduling
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* requests, rolling bloom filters for remembering transactions that have
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* already been {accepted, rejected, confirmed}, an orphanage, and a registry of
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* each peer's transaction relay-related information.
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*
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* Caller needs to interact with TxDownloadManager:
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* - ValidationInterface callbacks.
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* - When a potential transaction relay peer connects or disconnects.
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* - When a transaction or package is accepted or rejected from mempool
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* - When a inv, notfound, or tx message is received
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* - To get instructions for which getdata messages to send
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*
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* This class is not thread-safe. Access must be synchronized using an
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* external mutex.
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*/
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class TxDownloadManager {
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const std::unique_ptr<TxDownloadManagerImpl> m_impl;
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public:
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explicit TxDownloadManager();
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~TxDownloadManager();
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// Get references to internal data structures. Outside access to these data structures should be
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// temporary and removed later once logic has been moved internally.
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TxOrphanage& GetOrphanageRef();
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TxRequestTracker& GetTxRequestRef();
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CRollingBloomFilter& RecentRejectsFilter();
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CRollingBloomFilter& RecentRejectsReconsiderableFilter();
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CRollingBloomFilter& RecentConfirmedTransactionsFilter();
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};
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} // namespace node
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#endif // BITCOIN_NODE_TXDOWNLOADMAN_H
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// Copyright (c) 2024
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <node/txdownloadman_impl.h>
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#include <node/txdownloadman.h>
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namespace node {
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TxDownloadManager::TxDownloadManager() :
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m_impl{std::make_unique<TxDownloadManagerImpl>()}
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{}
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TxDownloadManager::~TxDownloadManager() = default;
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TxOrphanage& TxDownloadManager::GetOrphanageRef()
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{
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return m_impl->m_orphanage;
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}
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TxRequestTracker& TxDownloadManager::GetTxRequestRef()
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{
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return m_impl->m_txrequest;
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}
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CRollingBloomFilter& TxDownloadManager::RecentRejectsFilter()
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{
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return m_impl->RecentRejectsFilter();
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}
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CRollingBloomFilter& TxDownloadManager::RecentRejectsReconsiderableFilter()
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{
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return m_impl->RecentRejectsReconsiderableFilter();
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}
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CRollingBloomFilter& TxDownloadManager::RecentConfirmedTransactionsFilter()
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{
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return m_impl->RecentConfirmedTransactionsFilter();
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}
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} // namespace node
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// Copyright (c) 2024
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_NODE_TXDOWNLOADMAN_IMPL_H
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#define BITCOIN_NODE_TXDOWNLOADMAN_IMPL_H
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#include <node/txdownloadman.h>
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#include <common/bloom.h>
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#include <net.h>
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#include <txorphanage.h>
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#include <txrequest.h>
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namespace node {
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class TxDownloadManagerImpl {
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public:
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/** Manages unvalidated tx data (orphan transactions for which we are downloading ancestors). */
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TxOrphanage m_orphanage;
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/** Tracks candidates for requesting and downloading transaction data. */
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TxRequestTracker m_txrequest;
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/**
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* Filter for transactions that were recently rejected by the mempool.
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* These are not rerequested until the chain tip changes, at which point
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* the entire filter is reset.
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*
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* Without this filter we'd be re-requesting txs from each of our peers,
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* increasing bandwidth consumption considerably. For instance, with 100
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* peers, half of which relay a tx we don't accept, that might be a 50x
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* bandwidth increase. A flooding attacker attempting to roll-over the
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* filter using minimum-sized, 60byte, transactions might manage to send
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* 1000/sec if we have fast peers, so we pick 120,000 to give our peers a
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* two minute window to send invs to us.
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*
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* Decreasing the false positive rate is fairly cheap, so we pick one in a
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* million to make it highly unlikely for users to have issues with this
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* filter.
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*
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* We typically only add wtxids to this filter. For non-segwit
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* transactions, the txid == wtxid, so this only prevents us from
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* re-downloading non-segwit transactions when communicating with
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* non-wtxidrelay peers -- which is important for avoiding malleation
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* attacks that could otherwise interfere with transaction relay from
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* non-wtxidrelay peers. For communicating with wtxidrelay peers, having
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* the reject filter store wtxids is exactly what we want to avoid
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* redownload of a rejected transaction.
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*
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* In cases where we can tell that a segwit transaction will fail
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* validation no matter the witness, we may add the txid of such
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* transaction to the filter as well. This can be helpful when
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* communicating with txid-relay peers or if we were to otherwise fetch a
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* transaction via txid (eg in our orphan handling).
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*
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* Memory used: 1.3 MB
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*/
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std::unique_ptr<CRollingBloomFilter> m_lazy_recent_rejects{nullptr};
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CRollingBloomFilter& RecentRejectsFilter()
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{
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if (!m_lazy_recent_rejects) {
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m_lazy_recent_rejects = std::make_unique<CRollingBloomFilter>(120'000, 0.000'001);
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}
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return *m_lazy_recent_rejects;
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}
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/**
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* Filter for:
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* (1) wtxids of transactions that were recently rejected by the mempool but are
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* eligible for reconsideration if submitted with other transactions.
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* (2) packages (see GetPackageHash) we have already rejected before and should not retry.
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*
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* Similar to m_lazy_recent_rejects, this filter is used to save bandwidth when e.g. all of our peers
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* have larger mempools and thus lower minimum feerates than us.
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*
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* When a transaction's error is TxValidationResult::TX_RECONSIDERABLE (in a package or by
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* itself), add its wtxid to this filter. When a package fails for any reason, add the combined
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* hash to this filter.
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*
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* Upon receiving an announcement for a transaction, if it exists in this filter, do not
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* download the txdata. When considering packages, if it exists in this filter, drop it.
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*
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* Reset this filter when the chain tip changes.
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*
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* Parameters are picked to be the same as m_lazy_recent_rejects, with the same rationale.
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*/
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std::unique_ptr<CRollingBloomFilter> m_lazy_recent_rejects_reconsiderable{nullptr};
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CRollingBloomFilter& RecentRejectsReconsiderableFilter()
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{
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if (!m_lazy_recent_rejects_reconsiderable) {
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m_lazy_recent_rejects_reconsiderable = std::make_unique<CRollingBloomFilter>(120'000, 0.000'001);
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}
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return *m_lazy_recent_rejects_reconsiderable;
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}
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/*
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* Filter for transactions that have been recently confirmed.
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* We use this to avoid requesting transactions that have already been
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* confirnmed.
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*
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* Blocks don't typically have more than 4000 transactions, so this should
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* be at least six blocks (~1 hr) worth of transactions that we can store,
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* inserting both a txid and wtxid for every observed transaction.
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* If the number of transactions appearing in a block goes up, or if we are
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* seeing getdata requests more than an hour after initial announcement, we
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* can increase this number.
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* The false positive rate of 1/1M should come out to less than 1
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* transaction per day that would be inadvertently ignored (which is the
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* same probability that we have in the reject filter).
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*/
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std::unique_ptr<CRollingBloomFilter> m_lazy_recent_confirmed_transactions{nullptr};
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CRollingBloomFilter& RecentConfirmedTransactionsFilter()
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{
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if (!m_lazy_recent_confirmed_transactions) {
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m_lazy_recent_confirmed_transactions = std::make_unique<CRollingBloomFilter>(48'000, 0.000'001);
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}
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return *m_lazy_recent_confirmed_transactions;
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}
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TxDownloadManagerImpl() = default;
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};
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} // namespace node
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#endif // BITCOIN_NODE_TXDOWNLOADMAN_IMPL_H
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