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p2p: Finish negotiating reconciliation support

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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.
This commit is contained in:
Gleb Naumenko 2021-03-19 13:07:15 +02:00
parent 36cf6bf216
commit 88d326c8e3
3 changed files with 159 additions and 4 deletions
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54
src/net_processing.cpp
View file

@ -1782,7 +1782,7 @@ PeerManagerImpl::PeerManagerImpl(CConnman& connman, AddrMan& addrman,
// While Erlay support is incomplete, it must be enabled explicitly via -txreconciliation.
// This argument can go away after Erlay support is complete.
if (gArgs.GetBoolArg("-txreconciliation", DEFAULT_TXRECONCILIATION_ENABLE)) {
m_txreconciliation = std::make_unique<TxReconciliationTracker>();
m_txreconciliation = std::make_unique<TxReconciliationTracker>(TXRECONCILIATION_VERSION);
}
}
@ -3477,6 +3477,58 @@ void PeerManagerImpl::ProcessMessage(CNode& pfrom, const std::string& msg_type,
return;
}
// Received from a peer demonstrating readiness to announce transactions via reconciliations.
// This feature negotiation must happen between VERSION and VERACK to avoid relay problems
// from switching announcement protocols after the connection is up.
if (msg_type == NetMsgType::SENDTXRCNCL) {
if (!m_txreconciliation) {
LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "sendtxrcncl from peer=%d ignored, as our node does not have txreconciliation enabled\n", pfrom.GetId());
return;
}
if (pfrom.fSuccessfullyConnected) {
// Disconnect peers that send a SENDTXRCNCL message after VERACK.
LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "sendtxrcncl received after verack from peer=%d; disconnecting\n", pfrom.GetId());
pfrom.fDisconnect = true;
return;
}
if (!peer->GetTxRelay()) {
// Disconnect peers that send a SENDTXRCNCL message even though we indicated we don't
// support transaction relay.
LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "sendtxrcncl received from peer=%d to which we indicated no tx relay; disconnecting\n", pfrom.GetId());
pfrom.fDisconnect = true;
return;
}
bool is_peer_initiator, is_peer_responder;
uint32_t peer_txreconcl_version;
uint64_t remote_salt;
vRecv >> is_peer_initiator >> is_peer_responder >> peer_txreconcl_version >> remote_salt;
if (m_txreconciliation->IsPeerRegistered(pfrom.GetId())) {
// A peer is already registered, meaning we already received SENDTXRCNCL from them.
LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "txreconciliation protocol violation from peer=%d (sendtxrcncl received from already registered peer); disconnecting\n", pfrom.GetId());
pfrom.fDisconnect = true;
return;
}
const ReconciliationRegisterResult result = m_txreconciliation->RegisterPeer(pfrom.GetId(), pfrom.IsInboundConn(),
is_peer_initiator, is_peer_responder,
peer_txreconcl_version,
remote_salt);
// If it's a protocol violation, disconnect.
// If the peer was not found (but something unexpected happened) or it was registered,
// nothing to be done.
if (result == ReconciliationRegisterResult::PROTOCOL_VIOLATION) {
LogPrintLevel(BCLog::NET, BCLog::Level::Debug, "txreconciliation protocol violation from peer=%d; disconnecting\n", pfrom.GetId());
pfrom.fDisconnect = true;
return;
}
return;
}
if (!pfrom.fSuccessfullyConnected) {
LogPrint(BCLog::NET, "Unsupported message \"%s\" prior to verack from peer=%d\n", SanitizeString(msg_type), pfrom.GetId());
return;

94
src/node/txreconciliation.cpp
View file

@ -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);

15
src/node/txreconciliation.h
View file

@ -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();
/**
@ -62,6 +68,13 @@ 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.