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1 : : // Copyright (c) 2024
2 : : // Distributed under the MIT software license, see the accompanying
3 : : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
4 : : #ifndef BITCOIN_NODE_TXDOWNLOADMAN_IMPL_H
5 : : #define BITCOIN_NODE_TXDOWNLOADMAN_IMPL_H
6 : :
7 : : #include <node/txdownloadman.h>
8 : :
9 : : #include <common/bloom.h>
10 : : #include <consensus/validation.h>
11 : : #include <kernel/chain.h>
12 : : #include <net.h>
13 : : #include <primitives/transaction.h>
14 : : #include <policy/packages.h>
15 : : #include <txorphanage.h>
16 : : #include <txrequest.h>
17 : :
18 : : class CTxMemPool;
19 : : namespace node {
20 : : class TxDownloadManagerImpl {
21 : : public:
22 : : TxDownloadOptions m_opts;
23 : :
24 : : /** Manages unvalidated tx data (orphan transactions for which we are downloading ancestors). */
25 : : TxOrphanage m_orphanage;
26 : : /** Tracks candidates for requesting and downloading transaction data. */
27 : : TxRequestTracker m_txrequest;
28 : :
29 : : /**
30 : : * Filter for transactions that were recently rejected by the mempool.
31 : : * These are not rerequested until the chain tip changes, at which point
32 : : * the entire filter is reset.
33 : : *
34 : : * Without this filter we'd be re-requesting txs from each of our peers,
35 : : * increasing bandwidth consumption considerably. For instance, with 100
36 : : * peers, half of which relay a tx we don't accept, that might be a 50x
37 : : * bandwidth increase. A flooding attacker attempting to roll-over the
38 : : * filter using minimum-sized, 60byte, transactions might manage to send
39 : : * 1000/sec if we have fast peers, so we pick 120,000 to give our peers a
40 : : * two minute window to send invs to us.
41 : : *
42 : : * Decreasing the false positive rate is fairly cheap, so we pick one in a
43 : : * million to make it highly unlikely for users to have issues with this
44 : : * filter.
45 : : *
46 : : * We typically only add wtxids to this filter. For non-segwit
47 : : * transactions, the txid == wtxid, so this only prevents us from
48 : : * re-downloading non-segwit transactions when communicating with
49 : : * non-wtxidrelay peers -- which is important for avoiding malleation
50 : : * attacks that could otherwise interfere with transaction relay from
51 : : * non-wtxidrelay peers. For communicating with wtxidrelay peers, having
52 : : * the reject filter store wtxids is exactly what we want to avoid
53 : : * redownload of a rejected transaction.
54 : : *
55 : : * In cases where we can tell that a segwit transaction will fail
56 : : * validation no matter the witness, we may add the txid of such
57 : : * transaction to the filter as well. This can be helpful when
58 : : * communicating with txid-relay peers or if we were to otherwise fetch a
59 : : * transaction via txid (eg in our orphan handling).
60 : : *
61 : : * Memory used: 1.3 MB
62 : : */
63 : : std::unique_ptr<CRollingBloomFilter> m_lazy_recent_rejects{nullptr};
64 : :
65 : 696 : CRollingBloomFilter& RecentRejectsFilter()
66 : : {
67 [ + + ]: 696 : if (!m_lazy_recent_rejects) {
68 : 74 : m_lazy_recent_rejects = std::make_unique<CRollingBloomFilter>(120'000, 0.000'001);
69 : : }
70 : :
71 : 696 : return *m_lazy_recent_rejects;
72 : : }
73 : :
74 : : /**
75 : : * Filter for:
76 : : * (1) wtxids of transactions that were recently rejected by the mempool but are
77 : : * eligible for reconsideration if submitted with other transactions.
78 : : * (2) packages (see GetPackageHash) we have already rejected before and should not retry.
79 : : *
80 : : * Similar to m_lazy_recent_rejects, this filter is used to save bandwidth when e.g. all of our peers
81 : : * have larger mempools and thus lower minimum feerates than us.
82 : : *
83 : : * When a transaction's error is TxValidationResult::TX_RECONSIDERABLE (in a package or by
84 : : * itself), add its wtxid to this filter. When a package fails for any reason, add the combined
85 : : * hash to this filter.
86 : : *
87 : : * Upon receiving an announcement for a transaction, if it exists in this filter, do not
88 : : * download the txdata. When considering packages, if it exists in this filter, drop it.
89 : : *
90 : : * Reset this filter when the chain tip changes.
91 : : *
92 : : * Parameters are picked to be the same as m_lazy_recent_rejects, with the same rationale.
93 : : */
94 : : std::unique_ptr<CRollingBloomFilter> m_lazy_recent_rejects_reconsiderable{nullptr};
95 : :
96 : 335 : CRollingBloomFilter& RecentRejectsReconsiderableFilter()
97 : : {
98 [ + + ]: 335 : if (!m_lazy_recent_rejects_reconsiderable) {
99 : 70 : m_lazy_recent_rejects_reconsiderable = std::make_unique<CRollingBloomFilter>(120'000, 0.000'001);
100 : : }
101 : :
102 : 335 : return *m_lazy_recent_rejects_reconsiderable;
103 : : }
104 : :
105 : : /*
106 : : * Filter for transactions that have been recently confirmed.
107 : : * We use this to avoid requesting transactions that have already been
108 : : * confirmed.
109 : : *
110 : : * Blocks don't typically have more than 4000 transactions, so this should
111 : : * be at least six blocks (~1 hr) worth of transactions that we can store,
112 : : * inserting both a txid and wtxid for every observed transaction.
113 : : * If the number of transactions appearing in a block goes up, or if we are
114 : : * seeing getdata requests more than an hour after initial announcement, we
115 : : * can increase this number.
116 : : * The false positive rate of 1/1M should come out to less than 1
117 : : * transaction per day that would be inadvertently ignored (which is the
118 : : * same probability that we have in the reject filter).
119 : : */
120 : : std::unique_ptr<CRollingBloomFilter> m_lazy_recent_confirmed_transactions{nullptr};
121 : :
122 : 216 : CRollingBloomFilter& RecentConfirmedTransactionsFilter()
123 : : {
124 [ + + ]: 216 : if (!m_lazy_recent_confirmed_transactions) {
125 : 68 : m_lazy_recent_confirmed_transactions = std::make_unique<CRollingBloomFilter>(48'000, 0.000'001);
126 : : }
127 : :
128 : 216 : return *m_lazy_recent_confirmed_transactions;
129 : : }
130 : :
131 [ + - ]: 244 : TxDownloadManagerImpl(const TxDownloadOptions& options) : m_opts{options}, m_txrequest{options.m_deterministic_txrequest} {}
132 : :
133 : : struct PeerInfo {
134 : : /** Information relevant to scheduling tx requests. */
135 : : const TxDownloadConnectionInfo m_connection_info;
136 : :
137 : 75 : PeerInfo(const TxDownloadConnectionInfo& info) : m_connection_info{info} {}
138 : : };
139 : :
140 : : /** Information for all of the peers we may download transactions from. This is not necessarily
141 : : * all peers we are connected to (no block-relay-only and temporary connections). */
142 : : std::map<NodeId, PeerInfo> m_peer_info;
143 : :
144 : : /** Number of wtxid relay peers we have in m_peer_info. */
145 : : uint32_t m_num_wtxid_peers{0};
146 : :
147 : : void ActiveTipChange();
148 : : void BlockConnected(const std::shared_ptr<const CBlock>& pblock);
149 : : void BlockDisconnected();
150 : :
151 : : /** Check whether we already have this gtxid in:
152 : : * - mempool
153 : : * - orphanage
154 : : * - m_recent_rejects
155 : : * - m_recent_rejects_reconsiderable (if include_reconsiderable = true)
156 : : * - m_recent_confirmed_transactions
157 : : * */
158 : : bool AlreadyHaveTx(const GenTxid& gtxid, bool include_reconsiderable);
159 : :
160 : : void ConnectedPeer(NodeId nodeid, const TxDownloadConnectionInfo& info);
161 : : void DisconnectedPeer(NodeId nodeid);
162 : :
163 : : /** New inv has been received. May be added as a candidate to txrequest. */
164 : : bool AddTxAnnouncement(NodeId peer, const GenTxid& gtxid, std::chrono::microseconds now, bool p2p_inv);
165 : :
166 : : /** Get getdata requests to send. */
167 : : std::vector<GenTxid> GetRequestsToSend(NodeId nodeid, std::chrono::microseconds current_time);
168 : :
169 : : /** Marks a tx as ReceivedResponse in txrequest. */
170 : : void ReceivedNotFound(NodeId nodeid, const std::vector<uint256>& txhashes);
171 : :
172 : : /** Look for a child of this transaction in the orphanage to form a 1-parent-1-child package,
173 : : * skipping any combinations that have already been tried. Return the resulting package along with
174 : : * the senders of its respective transactions, or std::nullopt if no package is found. */
175 : : std::optional<PackageToValidate> Find1P1CPackage(const CTransactionRef& ptx, NodeId nodeid);
176 : :
177 : : void MempoolAcceptedTx(const CTransactionRef& tx);
178 : : RejectedTxTodo MempoolRejectedTx(const CTransactionRef& ptx, const TxValidationState& state, NodeId nodeid, bool first_time_failure);
179 : : void MempoolRejectedPackage(const Package& package);
180 : :
181 : : std::pair<bool, std::optional<PackageToValidate>> ReceivedTx(NodeId nodeid, const CTransactionRef& ptx);
182 : :
183 : : bool HaveMoreWork(NodeId nodeid);
184 : : CTransactionRef GetTxToReconsider(NodeId nodeid);
185 : :
186 : : void CheckIsEmpty();
187 : : void CheckIsEmpty(NodeId nodeid);
188 : :
189 : : std::vector<TxOrphanage::OrphanTxBase> GetOrphanTransactions() const;
190 : : };
191 : : } // namespace node
192 : : #endif // BITCOIN_NODE_TXDOWNLOADMAN_IMPL_H
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