Cleanup received_new_header calculation to use WITH_LOCK

Author: sdaftuar

src/net_processing.cpp

@@ -2420,7 +2420,6 @@ void PeerManagerImpl::ProcessHeadersMessage(CNode& pfrom, Peer& peer,
         return;
     }
 
-    bool received_new_header = false;
     const CBlockIndex *pindexLast = nullptr;
 
     // Do these headers connect to something in our block index?
@@ -2444,15 +2443,9 @@ void PeerManagerImpl::ProcessHeadersMessage(CNode& pfrom, Peer& peer,
         return;
     }
 
-    {
-        LOCK(cs_main);
-
-        // If we don't have the last header, then they'll have given us
-        // something new (if these headers are valid).
-        if (!m_chainman.m_blockman.LookupBlockIndex(headers.back().GetHash())) {
-            received_new_header = true;
-        }
-    }
+    // If we don't have the last header, then this peer will have given us
+    // something new (if these headers are valid).
+    bool received_new_header{WITH_LOCK(::cs_main, return m_chainman.m_blockman.LookupBlockIndex(headers.back().GetHash()) == nullptr)};
 
     BlockValidationState state;
     if (!m_chainman.ProcessNewBlockHeaders(headers, state, &pindexLast)) {