/root/bitcoin/src/private_broadcast.h

Source
// Copyright (c) 2023-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or https://opensource.org/license/mit/.

#ifndef BITCOIN_PRIVATE_BROADCAST_H
#define BITCOIN_PRIVATE_BROADCAST_H

#include <net.h>
#include <primitives/transaction.h>
#include <primitives/transaction_identifier.h>
#include <sync.h>
#include <util/time.h>

#include <optional>
#include <tuple>
#include <unordered_map>
#include <vector>

/**
 * Store a list of transactions to be broadcast privately. Supports the following operations:
 * - Add a new transaction
 * - Remove a transaction
 * - Pick a transaction for sending to one recipient
 * - Query which transaction has been picked for sending to a given recipient node
 * - Mark that a given recipient node has confirmed receipt of a transaction
 * - Query whether a given recipient node has confirmed reception
 * - Query whether any transactions that need sending are currently on the list
 */
class PrivateBroadcast
{
public:

    /// If a transaction is not sent to any peer for this duration,
    /// then we consider it stale / for rebroadcasting.
    static constexpr auto INITIAL_STALE_DURATION{5min};

    /// If a transaction is not received back from the network for this duration
    /// after it is broadcast, then we consider it stale / for rebroadcasting.
    static constexpr auto STALE_DURATION{1min};

    struct PeerSendInfo {
        CService address;
        NodeClock::time_point sent;
        std::optional<NodeClock::time_point> received;
    };

    struct TxBroadcastInfo {
        CTransactionRef tx;
        NodeClock::time_point time_added;
        std::vector<PeerSendInfo> peers;
    };

    /**
     * Add a transaction to the storage.
     * @param[in] tx The transaction to add.
     * @retval true The transaction was added.
     * @retval false The transaction was already present.
     */
    bool Add(const CTransactionRef& tx)
        EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);

    /**
     * Forget a transaction.
     * @param[in] tx Transaction to forget.
     * @retval !nullopt The number of times the transaction was sent and confirmed
     * by the recipient (if the transaction existed and was removed).
     * @retval nullopt The transaction was not in the storage.
     */
    std::optional<size_t> Remove(const CTransactionRef& tx)
        EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);

    /**
     * Pick the transaction with the fewest send attempts, and confirmations,
     * and oldest send/confirm times.
     * @param[in] will_send_to_nodeid Will remember that the returned transaction
     * was picked for sending to this node. Calling this method more than once with
     * the same `will_send_to_nodeid` is not allowed because sending more than one
     * transaction to one node would be a privacy leak.
     * @param[in] will_send_to_address Address of the peer to which this transaction
     * will be sent.
     * @return Most urgent transaction or nullopt if there are no transactions.
     */
    std::optional<CTransactionRef> PickTxForSend(const NodeId& will_send_to_nodeid, const CService& will_send_to_address)
        EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);

    /**
     * Get the transaction that was picked for sending to a given node by PickTxForSend().
     * @param[in] nodeid Node to which a transaction is being (or was) sent.
     * @return Transaction or nullopt if the nodeid is unknown.
     */
    std::optional<CTransactionRef> GetTxForNode(const NodeId& nodeid)
        EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);

    /**
     * Mark that the node has confirmed reception of the transaction we sent it by
     * responding with `PONG` to our `PING` message.
     * @param[in] nodeid Node that we sent a transaction to.
     */
    void NodeConfirmedReception(const NodeId& nodeid)
        EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);

    /**
     * Check if the node has confirmed reception of the transaction.
     * @retval true Node has confirmed, `NodeConfirmedReception()` has been called.
     * @retval false Node has not confirmed, `NodeConfirmedReception()` has not been called.
     */
    bool DidNodeConfirmReception(const NodeId& nodeid)
        EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);

    /**
     * Check if there are transactions that need to be broadcast.
     */
    bool HavePendingTransactions()
        EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);

    /**
     * Get the transactions that have not been broadcast recently.
     */
    std::vector<CTransactionRef> GetStale() const
        EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);

    /**
     * Get stats about all transactions currently being privately broadcast.
     */
    std::vector<TxBroadcastInfo> GetBroadcastInfo() const
        EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);

private:
    /// Status of a transaction sent to a given node.
    struct SendStatus {
        /// Node to which the transaction will be sent (or was sent).
        const NodeId nodeid;
        /// Address of the node.
        const CService address;
        /// When was the transaction picked for sending to the node.
        const NodeClock::time_point picked;
        /// When was the transaction reception confirmed by the node (by PONG).
        std::optional<NodeClock::time_point> confirmed;

        SendStatus(const NodeId& nodeid, const CService& address, const NodeClock::time_point& picked) : nodeid{nodeid}, address{address}, picked{picked} {}
    };

    /// Cumulative stats from all the send attempts for a transaction. Used to prioritize transactions.
    struct Priority {
        size_t num_picked{0}; ///< Number of times the transaction was picked for sending.
        NodeClock::time_point last_picked{}; ///< The most recent time when the transaction was picked for sending.
        size_t num_confirmed{0}; ///< Number of nodes that have confirmed reception of a transaction (by PONG).
        NodeClock::time_point last_confirmed{}; ///< The most recent time when the transaction was confirmed.

        auto operator<=>(const Priority& other) const
        {
            // Invert `other` and `this` in the comparison because smaller num_picked, num_confirmed or
            // earlier times mean greater priority. In other words, if this.num_picked < other.num_picked
            // then this > other.
            return std::tie(other.num_picked, other.num_confirmed, other.last_picked, other.last_confirmed) <=>
                   std::tie(num_picked, num_confirmed, last_picked, last_confirmed);
        }
    };

    /// A pair of a transaction and a sent status for a given node. Convenience return type of GetSendStatusByNode().
    struct TxAndSendStatusForNode {
        const CTransactionRef& tx;
        SendStatus& send_status;
    };

    // No need for salted hasher because we are going to store just a bunch of locally originating transactions.

    struct CTransactionRefHash {
        size_t operator()(const CTransactionRef& tx) const
        {
            return static_cast<size_t>(tx->GetWitnessHash().ToUint256().GetUint64(0));
        }
    };

    struct CTransactionRefComp {
        bool operator()(const CTransactionRef& a, const CTransactionRef& b) const
        {
            return a->GetWitnessHash() == b->GetWitnessHash(); // If wtxid equals, then txid also equals.
        }
    };

    /**
     * Derive the sending priority of a transaction.
     * @param[in] sent_to List of nodes that the transaction has been sent to.
     */
    static Priority DerivePriority(const std::vector<SendStatus>& sent_to);

    /**
     * Find which transaction we sent to a given node (marked by PickTxForSend()).
     * @return That transaction together with the send status or nullopt if we did not
     * send any transaction to the given node.
     */
    std::optional<TxAndSendStatusForNode> GetSendStatusByNode(const NodeId& nodeid)
        EXCLUSIVE_LOCKS_REQUIRED(m_mutex);
    struct TxSendStatus {
        const NodeClock::time_point time_added{NodeClock::now()};
        std::vector<SendStatus> send_statuses;
    };
    mutable Mutex m_mutex;
    std::unordered_map<CTransactionRef, TxSendStatus, CTransactionRefHash, CTransactionRefComp>
        m_transactions GUARDED_BY(m_mutex);
};

#endif // BITCOIN_PRIVATE_BROADCAST_H

Coverage Report

Created: 2026-07-01 15:07

Line	Count	Source
1		// Copyright (c) 2023-present The Bitcoin Core developers
2		// Distributed under the MIT software license, see the accompanying
3		// file COPYING or https://opensource.org/license/mit/.
4
5		#ifndef BITCOIN_PRIVATE_BROADCAST_H
6		#define BITCOIN_PRIVATE_BROADCAST_H
7
8		#include <net.h>
9		#include <primitives/transaction.h>
10		#include <primitives/transaction_identifier.h>
11		#include <sync.h>
12		#include <util/time.h>
13
14		#include <optional>
15		#include <tuple>
16		#include <unordered_map>
17		#include <vector>
18
19		/**
20		* Store a list of transactions to be broadcast privately. Supports the following operations:
21		* - Add a new transaction
22		* - Remove a transaction
23		* - Pick a transaction for sending to one recipient
24		* - Query which transaction has been picked for sending to a given recipient node
25		* - Mark that a given recipient node has confirmed receipt of a transaction
26		* - Query whether a given recipient node has confirmed reception
27		* - Query whether any transactions that need sending are currently on the list
28		*/
29		class PrivateBroadcast
30		{
31		public:
32
33		/// If a transaction is not sent to any peer for this duration,
34		/// then we consider it stale / for rebroadcasting.
35		static constexpr auto INITIAL_STALE_DURATION{5min};
36
37		/// If a transaction is not received back from the network for this duration
38		/// after it is broadcast, then we consider it stale / for rebroadcasting.
39		static constexpr auto STALE_DURATION{1min};
40
41		struct PeerSendInfo {
42		CService address;
43		NodeClock::time_point sent;
44		std::optional<NodeClock::time_point> received;
45		};
46
47		struct TxBroadcastInfo {
48		CTransactionRef tx;
49		NodeClock::time_point time_added;
50		std::vector<PeerSendInfo> peers;
51		};
52
53		/**
54		* Add a transaction to the storage.
55		* @param[in] tx The transaction to add.
56		* @retval true The transaction was added.
57		* @retval false The transaction was already present.
58		*/
59		bool Add(const CTransactionRef& tx)
60		EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
61
62		/**
63		* Forget a transaction.
64		* @param[in] tx Transaction to forget.
65		* @retval !nullopt The number of times the transaction was sent and confirmed
66		* by the recipient (if the transaction existed and was removed).
67		* @retval nullopt The transaction was not in the storage.
68		*/
69		std::optional<size_t> Remove(const CTransactionRef& tx)
70		EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
71
72		/**
73		* Pick the transaction with the fewest send attempts, and confirmations,
74		* and oldest send/confirm times.
75		* @param[in] will_send_to_nodeid Will remember that the returned transaction
76		* was picked for sending to this node. Calling this method more than once with
77		* the same `will_send_to_nodeid` is not allowed because sending more than one
78		* transaction to one node would be a privacy leak.
79		* @param[in] will_send_to_address Address of the peer to which this transaction
80		* will be sent.
81		* @return Most urgent transaction or nullopt if there are no transactions.
82		*/
83		std::optional<CTransactionRef> PickTxForSend(const NodeId& will_send_to_nodeid, const CService& will_send_to_address)
84		EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
85
86		/**
87		* Get the transaction that was picked for sending to a given node by PickTxForSend().
88		* @param[in] nodeid Node to which a transaction is being (or was) sent.
89		* @return Transaction or nullopt if the nodeid is unknown.
90		*/
91		std::optional<CTransactionRef> GetTxForNode(const NodeId& nodeid)
92		EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
93
94		/**
95		* Mark that the node has confirmed reception of the transaction we sent it by
96		* responding with `PONG` to our `PING` message.
97		* @param[in] nodeid Node that we sent a transaction to.
98		*/
99		void NodeConfirmedReception(const NodeId& nodeid)
100		EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
101
102		/**
103		* Check if the node has confirmed reception of the transaction.
104		* @retval true Node has confirmed, `NodeConfirmedReception()` has been called.
105		* @retval false Node has not confirmed, `NodeConfirmedReception()` has not been called.
106		*/
107		bool DidNodeConfirmReception(const NodeId& nodeid)
108		EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
109
110		/**
111		* Check if there are transactions that need to be broadcast.
112		*/
113		bool HavePendingTransactions()
114		EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
115
116		/**
117		* Get the transactions that have not been broadcast recently.
118		*/
119		std::vector<CTransactionRef> GetStale() const
120		EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
121
122		/**
123		* Get stats about all transactions currently being privately broadcast.
124		*/
125		std::vector<TxBroadcastInfo> GetBroadcastInfo() const
126		EXCLUSIVE_LOCKS_REQUIRED(!m_mutex);
127
128		private:
129		/// Status of a transaction sent to a given node.
130		struct SendStatus {
131		/// Node to which the transaction will be sent (or was sent).
132		const NodeId nodeid;
133		/// Address of the node.
134		const CService address;
135		/// When was the transaction picked for sending to the node.
136		const NodeClock::time_point picked;
137		/// When was the transaction reception confirmed by the node (by PONG).
138		std::optional<NodeClock::time_point> confirmed;
139
140	0	SendStatus(const NodeId& nodeid, const CService& address, const NodeClock::time_point& picked) : nodeid{nodeid}, address{address}, picked{picked} {}
141		};
142
143		/// Cumulative stats from all the send attempts for a transaction. Used to prioritize transactions.
144		struct Priority {
145		size_t num_picked{0}; ///< Number of times the transaction was picked for sending.
146		NodeClock::time_point last_picked{}; ///< The most recent time when the transaction was picked for sending.
147		size_t num_confirmed{0}; ///< Number of nodes that have confirmed reception of a transaction (by PONG).
148		NodeClock::time_point last_confirmed{}; ///< The most recent time when the transaction was confirmed.
149
150		auto operator<=>(const Priority& other) const
151	0	{
152		// Invert `other` and `this` in the comparison because smaller num_picked, num_confirmed or
153		// earlier times mean greater priority. In other words, if this.num_picked < other.num_picked
154		// then this > other.
155	0	return std::tie(other.num_picked, other.num_confirmed, other.last_picked, other.last_confirmed) <=>
156	0	std::tie(num_picked, num_confirmed, last_picked, last_confirmed);
157	0	}
158		};
159
160		/// A pair of a transaction and a sent status for a given node. Convenience return type of GetSendStatusByNode().
161		struct TxAndSendStatusForNode {
162		const CTransactionRef& tx;
163		SendStatus& send_status;
164		};
165
166		// No need for salted hasher because we are going to store just a bunch of locally originating transactions.
167
168		struct CTransactionRefHash {
169		size_t operator()(const CTransactionRef& tx) const
170	0	{
171	0	return static_cast<size_t>(tx->GetWitnessHash().ToUint256().GetUint64(0));
172	0	}
173		};
174
175		struct CTransactionRefComp {
176		bool operator()(const CTransactionRef& a, const CTransactionRef& b) const
177	0	{
178	0	return a->GetWitnessHash() == b->GetWitnessHash(); // If wtxid equals, then txid also equals.
179	0	}
180		};
181
182		/**
183		* Derive the sending priority of a transaction.
184		* @param[in] sent_to List of nodes that the transaction has been sent to.
185		*/
186		static Priority DerivePriority(const std::vector<SendStatus>& sent_to);
187
188		/**
189		* Find which transaction we sent to a given node (marked by PickTxForSend()).
190		* @return That transaction together with the send status or nullopt if we did not
191		* send any transaction to the given node.
192		*/
193		std::optional<TxAndSendStatusForNode> GetSendStatusByNode(const NodeId& nodeid)
194		EXCLUSIVE_LOCKS_REQUIRED(m_mutex);
195		struct TxSendStatus {
196		const NodeClock::time_point time_added{NodeClock::now()};
197		std::vector<SendStatus> send_statuses;
198		};
199		mutable Mutex m_mutex;
200		std::unordered_map<CTransactionRef, TxSendStatus, CTransactionRefHash, CTransactionRefComp>
201		m_transactions GUARDED_BY(m_mutex);
202		};
203
204		#endif // BITCOIN_PRIVATE_BROADCAST_H