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net: fix race condition in self-connect detection #1472

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Merged
delta1 merged 1 commit into from
Jul 9, 2025
Merged

net: fix race condition in self-connect detection #1472

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2 changes: 1 addition & 1 deletion src/net.h
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Original file line number Diff line number Diff line change
Expand Up @@ -727,7 +727,7 @@ class NetEventsInterface
{
public:
/** Initialize a peer (setup state, queue any initial messages) */
virtual void InitializeNode(CNode* pnode) = 0;
virtual void InitializeNode(const CNode* pnode) = 0;

/** Handle removal of a peer (clear state) */
virtual void FinalizeNode(const CNode& node) = 0;
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22 changes: 17 additions & 5 deletions src/net_processing.cpp
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Expand Up @@ -222,6 +222,10 @@ struct Peer {
* Most peers use headers-first syncing, which doesn't use this mechanism */
uint256 m_continuation_block GUARDED_BY(m_block_inv_mutex) {};

Mutex m_msgproc_mutex;
/** Set to true once initial VERSION message was sent (only relevant for outbound peers). */
bool m_outbound_version_message_sent GUARDED_BY(m_msgproc_mutex){false};

/** This peer's reported block height when we connected */
std::atomic<int> m_starting_height{-1};

Expand Down Expand Up @@ -312,7 +316,7 @@ class PeerManagerImpl final : public PeerManager
void NewPoWValidBlock(const CBlockIndex *pindex, const std::shared_ptr<const CBlock>& pblock) override;

/** Implement NetEventsInterface */
void InitializeNode(CNode* pnode) override;
void InitializeNode(const CNode* pnode) override;
void FinalizeNode(const CNode& node) override;
bool ProcessMessages(CNode* pfrom, std::atomic<bool>& interrupt) override;
bool SendMessages(CNode* pto) override EXCLUSIVE_LOCKS_REQUIRED(pto->cs_sendProcessing);
Expand Down Expand Up @@ -1189,7 +1193,7 @@ void UpdateLastBlockAnnounceTime(NodeId node, int64_t time_in_seconds)
if (state) state->m_last_block_announcement = time_in_seconds;
}

void PeerManagerImpl::InitializeNode(CNode *pnode)
void PeerManagerImpl::InitializeNode(const CNode *pnode)
{
NodeId nodeid = pnode->GetId();
{
Expand All @@ -1202,9 +1206,6 @@ void PeerManagerImpl::InitializeNode(CNode *pnode)
LOCK(m_peer_mutex);
m_peer_map.emplace_hint(m_peer_map.end(), nodeid, std::move(peer));
}
if (!pnode->IsInboundConn()) {
PushNodeVersion(*pnode);
}
}

void PeerManagerImpl::ReattemptInitialBroadcast(CScheduler& scheduler)
Expand Down Expand Up @@ -4201,6 +4202,10 @@ bool PeerManagerImpl::ProcessMessages(CNode* pfrom, std::atomic<bool>& interrupt
PeerRef peer = GetPeerRef(pfrom->GetId());
if (peer == nullptr) return false;

// For outbound connections, ensure that the initial VERSION message
// has been sent first before processing any incoming messages
if (!pfrom->IsInboundConn() && WITH_LOCK(peer->m_msgproc_mutex, return !peer->m_outbound_version_message_sent)) return false;

{
LOCK(peer->m_getdata_requests_mutex);
if (!peer->m_getdata_requests.empty()) {
Expand Down Expand Up @@ -4660,6 +4665,13 @@ bool PeerManagerImpl::SendMessages(CNode* pto)
// disconnect misbehaving peers even before the version handshake is complete.
if (MaybeDiscourageAndDisconnect(*pto, *peer)) return true;

// Initiate version handshake for outbound connections
if (!pto->IsInboundConn() && WITH_LOCK(peer->m_msgproc_mutex, return !peer->m_outbound_version_message_sent)) {
LOCK(peer->m_msgproc_mutex);
PushNodeVersion(*pto);
peer->m_outbound_version_message_sent = true;
}

// Don't send anything until the version handshake is complete
if (!pto->fSuccessfullyConnected || pto->fDisconnect)
return true;
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6 changes: 3 additions & 3 deletions src/test/fuzz/util.cpp
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Expand Up @@ -244,13 +244,13 @@ void FillNode(FuzzedDataProvider& fuzzed_data_provider, ConnmanTestMsg& connman,
filter_txs),
};

(void)connman.ReceiveMsgFrom(node, msg_version);
node.fPauseSend = false;
connman.ProcessMessagesOnce(node);
{
LOCK(node.cs_sendProcessing);
peerman.SendMessages(&node);
}
(void)connman.ReceiveMsgFrom(node, msg_version);
node.fPauseSend = false;
connman.ProcessMessagesOnce(node);
if (node.fDisconnect) return;
assert(node.nVersion == version);
assert(node.GetCommonVersion() == std::min(version, PROTOCOL_VERSION));
Expand Down