Move peer state updates from headers message into separate function

src/net_processing.cpp

@@ -571,6 +571,8 @@ private:
     void FetchMoreHeaders(CNode& pfrom, const CBlockIndex *pindexLast, const Peer& peer);
     /** Potentially fetch blocks from this peer upon receipt of new headers tip */
     void HeadersDirectFetchBlocks(CNode& pfrom, const CBlockIndex* pindexLast);
+    /** Update peer state based on received headers message */
+    void UpdatePeerStateForReceivedHeaders(CNode& pfrom, const CBlockIndex *pindexLast, bool received_new_header, bool may_have_more_headers);
 
     void SendBlockTransactions(CNode& pfrom, Peer& peer, const CBlock& block, const BlockTransactionsRequest& req);
 
@@ -2345,6 +2347,67 @@ void PeerManagerImpl::HeadersDirectFetchBlocks(CNode& pfrom, const CBlockIndex*
     }
 }
 
+/**
+ * Given receipt of headers from a peer ending in pindexLast, along with
+ * whether that header was new and whether the headers message was full,
+ * update the state we keep for the peer.
+ */
+void PeerManagerImpl::UpdatePeerStateForReceivedHeaders(CNode& pfrom,
+        const CBlockIndex *pindexLast, bool received_new_header, bool may_have_more_headers)
+{
+    LOCK(cs_main);
+    CNodeState *nodestate = State(pfrom.GetId());
+    if (nodestate->nUnconnectingHeaders > 0) {
+        LogPrint(BCLog::NET, "peer=%d: resetting nUnconnectingHeaders (%d -> 0)\n", pfrom.GetId(), nodestate->nUnconnectingHeaders);
+    }
+    nodestate->nUnconnectingHeaders = 0;
+
+    assert(pindexLast);
+    UpdateBlockAvailability(pfrom.GetId(), pindexLast->GetBlockHash());
+
+    // From here, pindexBestKnownBlock should be guaranteed to be non-null,
+    // because it is set in UpdateBlockAvailability. Some nullptr checks
+    // are still present, however, as belt-and-suspenders.
+
+    if (received_new_header && pindexLast->nChainWork > m_chainman.ActiveChain().Tip()->nChainWork) {
+        nodestate->m_last_block_announcement = GetTime();
+    }
+
+    // If we're in IBD, we want outbound peers that will serve us a useful
+    // chain. Disconnect peers that are on chains with insufficient work.
+    if (m_chainman.ActiveChainstate().IsInitialBlockDownload() && !may_have_more_headers) {
+        // If the peer has no more headers to give us, then we know we have
+        // their tip.
+        if (nodestate->pindexBestKnownBlock && nodestate->pindexBestKnownBlock->nChainWork < nMinimumChainWork) {
+            // This peer has too little work on their headers chain to help
+            // us sync -- disconnect if it is an outbound disconnection
+            // candidate.
+            // Note: We compare their tip to nMinimumChainWork (rather than
+            // m_chainman.ActiveChain().Tip()) because we won't start block download
+            // until we have a headers chain that has at least
+            // nMinimumChainWork, even if a peer has a chain past our tip,
+            // as an anti-DoS measure.
+            if (pfrom.IsOutboundOrBlockRelayConn()) {
+                LogPrintf("Disconnecting outbound peer %d -- headers chain has insufficient work\n", pfrom.GetId());
+                pfrom.fDisconnect = true;
+            }
+        }
+    }
+
+    // If this is an outbound full-relay peer, check to see if we should protect
+    // it from the bad/lagging chain logic.
+    // Note that outbound block-relay peers are excluded from this protection, and
+    // thus always subject to eviction under the bad/lagging chain logic.
+    // See ChainSyncTimeoutState.
+    if (!pfrom.fDisconnect && pfrom.IsFullOutboundConn() && nodestate->pindexBestKnownBlock != nullptr) {
+        if (m_outbound_peers_with_protect_from_disconnect < MAX_OUTBOUND_PEERS_TO_PROTECT_FROM_DISCONNECT && nodestate->pindexBestKnownBlock->nChainWork >= m_chainman.ActiveChain().Tip()->nChainWork && !nodestate->m_chain_sync.m_protect) {
+            LogPrint(BCLog::NET, "Protecting outbound peer=%d from eviction\n", pfrom.GetId());
+            nodestate->m_chain_sync.m_protect = true;
+            ++m_outbound_peers_with_protect_from_disconnect;
+        }
+    }
+}
+
 void PeerManagerImpl::ProcessHeadersMessage(CNode& pfrom, Peer& peer,
                                             const std::vector<CBlockHeader>& headers,
                                             bool via_compact_block)
@@ -2405,59 +2468,7 @@ void PeerManagerImpl::ProcessHeadersMessage(CNode& pfrom, Peer& peer,
         FetchMoreHeaders(pfrom, pindexLast, peer);
     }
 
-    {
+    UpdatePeerStateForReceivedHeaders(pfrom, pindexLast, received_new_header, nCount == MAX_HEADERS_RESULTS);
-        LOCK(cs_main);
-        CNodeState *nodestate = State(pfrom.GetId());
-        if (nodestate->nUnconnectingHeaders > 0) {
-            LogPrint(BCLog::NET, "peer=%d: resetting nUnconnectingHeaders (%d -> 0)\n", pfrom.GetId(), nodestate->nUnconnectingHeaders);
-        }
-        nodestate->nUnconnectingHeaders = 0;
-
-        assert(pindexLast);
-        UpdateBlockAvailability(pfrom.GetId(), pindexLast->GetBlockHash());
-
-        // From here, pindexBestKnownBlock should be guaranteed to be non-null,
-        // because it is set in UpdateBlockAvailability. Some nullptr checks
-        // are still present, however, as belt-and-suspenders.
-
-        if (received_new_header && pindexLast->nChainWork > m_chainman.ActiveChain().Tip()->nChainWork) {
-            nodestate->m_last_block_announcement = GetTime();
-        }
-
-        // If we're in IBD, we want outbound peers that will serve us a useful
-        // chain. Disconnect peers that are on chains with insufficient work.
-        if (m_chainman.ActiveChainstate().IsInitialBlockDownload() && nCount != MAX_HEADERS_RESULTS) {
-            // When nCount < MAX_HEADERS_RESULTS, we know we have no more
-            // headers to fetch from this peer.
-            if (nodestate->pindexBestKnownBlock && nodestate->pindexBestKnownBlock->nChainWork < nMinimumChainWork) {
-                // This peer has too little work on their headers chain to help
-                // us sync -- disconnect if it is an outbound disconnection
-                // candidate.
-                // Note: We compare their tip to nMinimumChainWork (rather than
-                // m_chainman.ActiveChain().Tip()) because we won't start block download
-                // until we have a headers chain that has at least
-                // nMinimumChainWork, even if a peer has a chain past our tip,
-                // as an anti-DoS measure.
-                if (pfrom.IsOutboundOrBlockRelayConn()) {
-                    LogPrintf("Disconnecting outbound peer %d -- headers chain has insufficient work\n", pfrom.GetId());
-                    pfrom.fDisconnect = true;
-                }
-            }
-        }
-
-        // If this is an outbound full-relay peer, check to see if we should protect
-        // it from the bad/lagging chain logic.
-        // Note that outbound block-relay peers are excluded from this protection, and
-        // thus always subject to eviction under the bad/lagging chain logic.
-        // See ChainSyncTimeoutState.
-        if (!pfrom.fDisconnect && pfrom.IsFullOutboundConn() && nodestate->pindexBestKnownBlock != nullptr) {
-            if (m_outbound_peers_with_protect_from_disconnect < MAX_OUTBOUND_PEERS_TO_PROTECT_FROM_DISCONNECT && nodestate->pindexBestKnownBlock->nChainWork >= m_chainman.ActiveChain().Tip()->nChainWork && !nodestate->m_chain_sync.m_protect) {
-                LogPrint(BCLog::NET, "Protecting outbound peer=%d from eviction\n", pfrom.GetId());
-                nodestate->m_chain_sync.m_protect = true;
-                ++m_outbound_peers_with_protect_from_disconnect;
-            }
-        }
-    }
 
     // Consider immediately downloading blocks.
     HeadersDirectFetchBlocks(pfrom, pindexLast);