From 4470acf076289831ac60bcbafb6b3afa0e98e99d Mon Sep 17 00:00:00 2001
From: Gleb Naumenko <naumenko.gs@gmail.com>
Date: Sat, 20 Mar 2021 12:50:02 +0200
Subject: [PATCH] p2p: Forget peer's reconciliation state on disconnect

---
 src/net_processing.cpp        |  1 +
 src/node/txreconciliation.cpp | 14 ++++++++++++++
 src/node/txreconciliation.h   |  6 ++++++
 3 files changed, 21 insertions(+)

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index a10b6bfc471..af8afe235e3 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1494,6 +1494,7 @@ void PeerManagerImpl::FinalizeNode(const CNode& node)
     }
     WITH_LOCK(g_cs_orphans, m_orphanage.EraseForPeer(nodeid));
     m_txrequest.DisconnectedPeer(nodeid);
+    if (m_txreconciliation) m_txreconciliation->ForgetPeer(nodeid);
     m_num_preferred_download_peers -= state->fPreferredDownload;
     m_peers_downloading_from -= (state->nBlocksInFlight != 0);
     assert(m_peers_downloading_from >= 0);
diff --git a/src/node/txreconciliation.cpp b/src/node/txreconciliation.cpp
index dfac2ad82ed..d8cb1564759 100644
--- a/src/node/txreconciliation.cpp
+++ b/src/node/txreconciliation.cpp
@@ -54,6 +54,15 @@ public:
         Assert(m_states.emplace(peer_id, local_salt).second);
         return local_salt;
     }
+
+    void ForgetPeer(NodeId peer_id) EXCLUSIVE_LOCKS_REQUIRED(!m_txreconciliation_mutex)
+    {
+        AssertLockNotHeld(m_txreconciliation_mutex);
+        LOCK(m_txreconciliation_mutex);
+        if (m_states.erase(peer_id)) {
+            LogPrintLevel(BCLog::TXRECONCILIATION, BCLog::Level::Debug, "Forget txreconciliation state of peer=%d\n", peer_id);
+        }
+    }
 };
 
 TxReconciliationTracker::TxReconciliationTracker() : m_impl{std::make_unique<TxReconciliationTracker::Impl>()} {}
@@ -64,3 +73,8 @@ uint64_t TxReconciliationTracker::PreRegisterPeer(NodeId peer_id)
 {
     return m_impl->PreRegisterPeer(peer_id);
 }
+
+void TxReconciliationTracker::ForgetPeer(NodeId peer_id)
+{
+    m_impl->ForgetPeer(peer_id);
+}
diff --git a/src/node/txreconciliation.h b/src/node/txreconciliation.h
index 6e94a51cf24..b8e9b649c08 100644
--- a/src/node/txreconciliation.h
+++ b/src/node/txreconciliation.h
@@ -61,6 +61,12 @@ public:
      * This function must be called only once per peer.
      */
     uint64_t PreRegisterPeer(NodeId peer_id);
+
+    /**
+     * 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.
+     */
+    void ForgetPeer(NodeId peer_id);
 };
 
 #endif // BITCOIN_NODE_TXRECONCILIATION_H