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author | Gleb Naumenko <naumenko.gs@gmail.com> | 2021-03-19 13:07:15 +0200 |
---|---|---|
committer | Gleb Naumenko <naumenko.gs@gmail.com> | 2022-10-17 12:35:44 +0300 |
commit | 88d326c8e3796b9685c141fa50628615d3e43a38 (patch) | |
tree | 98bb2b47ec3bf6a0c5a62d5c59f346d34fee8a55 /src/node | |
parent | 36cf6bf2168f9f154a652c91bbb96480c2e1d044 (diff) | |
download | bitcoin-88d326c8e3796b9685c141fa50628615d3e43a38.tar.xz |
p2p: Finish negotiating reconciliation support
Once we received a reconciliation announcement support
message from a peer and it doesn't violate our protocol,
we store the negotiated parameters which will be used
for future reconciliations.
Diffstat (limited to 'src/node')
-rw-r--r-- | src/node/txreconciliation.cpp | 94 | ||||
-rw-r--r-- | src/node/txreconciliation.h | 15 |
2 files changed, 106 insertions, 3 deletions
diff --git a/src/node/txreconciliation.cpp b/src/node/txreconciliation.cpp index f35beae28b..974358fcda 100644 --- a/src/node/txreconciliation.cpp +++ b/src/node/txreconciliation.cpp @@ -13,11 +13,46 @@ namespace { +/** Static salt component used to compute short txids for sketch construction, see BIP-330. */ +const std::string RECON_STATIC_SALT = "Tx Relay Salting"; +const HashWriter RECON_SALT_HASHER = TaggedHash(RECON_STATIC_SALT); + +/** + * Salt (specified by BIP-330) constructed from contributions from both peers. It is used + * to compute transaction short IDs, which are then used to construct a sketch representing a set + * of transactions we want to announce to the peer. + */ +uint256 ComputeSalt(uint64_t salt1, uint64_t salt2) +{ + // According to BIP-330, salts should be combined in ascending order. + return (HashWriter(RECON_SALT_HASHER) << std::min(salt1, salt2) << std::max(salt1, salt2)).GetSHA256(); +} + /** * Keeps track of txreconciliation-related per-peer state. */ class TxReconciliationState { +public: + /** + * TODO: This field is public to ignore -Wunused-private-field. Make private once used in + * the following commits. + * + * Reconciliation protocol assumes using one role consistently: either a reconciliation + * initiator (requesting sketches), or responder (sending sketches). This defines our role. + * + */ + bool m_we_initiate; + + /** + * TODO: These fields are public to ignore -Wunused-private-field. Make private once used in + * the following commits. + * + * These values are used to salt short IDs, which is necessary for transaction reconciliations. + */ + uint64_t m_k0, m_k1; + + TxReconciliationState(bool we_initiate, uint64_t k0, uint64_t k1) : m_we_initiate(we_initiate), m_k0(k0), m_k1(k1) {} }; } // namespace @@ -28,6 +63,9 @@ class TxReconciliationTracker::Impl private: mutable Mutex m_txreconciliation_mutex; + // Local protocol version + uint32_t m_recon_version; + /** * Keeps track of txreconciliation states of eligible peers. * For pre-registered peers, the locally generated salt is stored. @@ -37,7 +75,7 @@ private: std::unordered_map<NodeId, std::variant<uint64_t, TxReconciliationState>> m_states GUARDED_BY(m_txreconciliation_mutex); public: - explicit Impl() {} + explicit Impl(uint32_t recon_version) : m_recon_version(recon_version) {} uint64_t PreRegisterPeer(NodeId peer_id) EXCLUSIVE_LOCKS_REQUIRED(!m_txreconciliation_mutex) { @@ -55,6 +93,50 @@ public: return local_salt; } + ReconciliationRegisterResult RegisterPeer(NodeId peer_id, bool is_peer_inbound, bool is_peer_recon_initiator, + bool is_peer_recon_responder, uint32_t peer_recon_version, + uint64_t remote_salt) EXCLUSIVE_LOCKS_REQUIRED(!m_txreconciliation_mutex) + { + AssertLockNotHeld(m_txreconciliation_mutex); + LOCK(m_txreconciliation_mutex); + auto recon_state = m_states.find(peer_id); + + // A peer should be in the pre-registered state to proceed here. + if (recon_state == m_states.end()) return NOT_FOUND; + uint64_t* local_salt = std::get_if<uint64_t>(&recon_state->second); + // A peer is already registered. This should be checked by the caller. + Assume(local_salt); + + // If the peer supports the version which is lower than ours, we downgrade to the version + // it supports. For now, this only guarantees that nodes with future reconciliation + // versions have the choice of reconciling with this current version. However, they also + // have the choice to refuse supporting reconciliations if the common version is not + // satisfactory (e.g. too low). + const uint32_t recon_version{std::min(peer_recon_version, m_recon_version)}; + // v1 is the lowest version, so suggesting something below must be a protocol violation. + if (recon_version < 1) return PROTOCOL_VIOLATION; + + // Must match SENDTXRCNCL logic. + const bool they_initiate = is_peer_recon_initiator && is_peer_inbound; + const bool we_initiate = !is_peer_inbound && is_peer_recon_responder; + + // If we ever announce support for both requesting and responding, this will need + // tie-breaking. For now, this is mutually exclusive because both are based on the + // inbound flag. + assert(!(they_initiate && we_initiate)); + + // The peer set both flags to false, we treat it as a protocol violation. + if (!(they_initiate || we_initiate)) return PROTOCOL_VIOLATION; + + LogPrintLevel(BCLog::TXRECONCILIATION, BCLog::Level::Debug, "Register peer=%d with the following params: " /* Continued */ + "we_initiate=%i, they_initiate=%i.\n", + peer_id, we_initiate, they_initiate); + + const uint256 full_salt{ComputeSalt(*local_salt, remote_salt)}; + recon_state->second = TxReconciliationState(we_initiate, full_salt.GetUint64(0), full_salt.GetUint64(1)); + return SUCCESS; + } + void ForgetPeer(NodeId peer_id) EXCLUSIVE_LOCKS_REQUIRED(!m_txreconciliation_mutex) { AssertLockNotHeld(m_txreconciliation_mutex); @@ -74,7 +156,7 @@ public: } }; -TxReconciliationTracker::TxReconciliationTracker() : m_impl{std::make_unique<TxReconciliationTracker::Impl>()} {} +TxReconciliationTracker::TxReconciliationTracker(uint32_t recon_version) : m_impl{std::make_unique<TxReconciliationTracker::Impl>(recon_version)} {} TxReconciliationTracker::~TxReconciliationTracker() = default; @@ -83,6 +165,14 @@ uint64_t TxReconciliationTracker::PreRegisterPeer(NodeId peer_id) return m_impl->PreRegisterPeer(peer_id); } +ReconciliationRegisterResult TxReconciliationTracker::RegisterPeer(NodeId peer_id, bool is_peer_inbound, + bool is_peer_recon_initiator, bool is_peer_recon_responder, + uint32_t peer_recon_version, uint64_t remote_salt) +{ + return m_impl->RegisterPeer(peer_id, is_peer_inbound, is_peer_recon_initiator, is_peer_recon_responder, + peer_recon_version, remote_salt); +} + void TxReconciliationTracker::ForgetPeer(NodeId peer_id) { m_impl->ForgetPeer(peer_id); diff --git a/src/node/txreconciliation.h b/src/node/txreconciliation.h index 1bffbea9db..a4f0870914 100644 --- a/src/node/txreconciliation.h +++ b/src/node/txreconciliation.h @@ -16,6 +16,12 @@ static constexpr bool DEFAULT_TXRECONCILIATION_ENABLE{false}; /** Supported transaction reconciliation protocol version */ static constexpr uint32_t TXRECONCILIATION_VERSION{1}; +enum ReconciliationRegisterResult { + NOT_FOUND = 0, + SUCCESS = 1, + PROTOCOL_VIOLATION = 2, +}; + /** * Transaction reconciliation is a way for nodes to efficiently announce transactions. * This object keeps track of all txreconciliation-related communications with the peers. @@ -50,7 +56,7 @@ private: const std::unique_ptr<Impl> m_impl; public: - explicit TxReconciliationTracker(); + explicit TxReconciliationTracker(uint32_t recon_version); ~TxReconciliationTracker(); /** @@ -63,6 +69,13 @@ public: uint64_t PreRegisterPeer(NodeId peer_id); /** + * Step 0. Once the peer agreed to reconcile txs with us, generate the state required to track + * ongoing reconciliations. Must be called only after pre-registering the peer and only once. + */ + ReconciliationRegisterResult RegisterPeer(NodeId peer_id, bool is_peer_inbound, bool is_peer_recon_initiator, + bool is_peer_recon_responder, uint32_t peer_recon_version, uint64_t remote_salt); + + /** * Attempts to forget txreconciliation-related state of the peer (if we previously stored any). * After this, we won't be able to reconcile transactions with the peer. */ |