[net processing] Tolerate sendheaders and sendcmpct messages before verack

BIP 130 (sendheaders) and BIP 152 (compact blocks) do not specify at
which stage the `sendheaders` or `sendcmpct` messages should be sent.
Therefore we should tolerate them being sent before the version-verack
handshake is complete.

Author: jnewbery

src/net_processing.cpp

@@ -2503,6 +2503,39 @@ void PeerManager::ProcessMessage(CNode& pfrom, const std::string& msg_type, CDat
         return;
     }
 
+    if (msg_type == NetMsgType::SENDHEADERS) {
+        LOCK(cs_main);
+        State(pfrom.GetId())->fPreferHeaders = true;
+        return;
+    }
+
+    if (msg_type == NetMsgType::SENDCMPCT) {
+        bool fAnnounceUsingCMPCTBLOCK = false;
+        uint64_t nCMPCTBLOCKVersion = 0;
+        vRecv >> fAnnounceUsingCMPCTBLOCK >> nCMPCTBLOCKVersion;
+        if (nCMPCTBLOCKVersion == 1 || ((pfrom.GetLocalServices() & NODE_WITNESS) && nCMPCTBLOCKVersion == 2)) {
+            LOCK(cs_main);
+            // fProvidesHeaderAndIDs is used to "lock in" version of compact blocks we send (fWantsCmpctWitness)
+            if (!State(pfrom.GetId())->fProvidesHeaderAndIDs) {
+                State(pfrom.GetId())->fProvidesHeaderAndIDs = true;
+                State(pfrom.GetId())->fWantsCmpctWitness = nCMPCTBLOCKVersion == 2;
+            }
+            if (State(pfrom.GetId())->fWantsCmpctWitness == (nCMPCTBLOCKVersion == 2)) { // ignore later version announces
+                State(pfrom.GetId())->fPreferHeaderAndIDs = fAnnounceUsingCMPCTBLOCK;
+                // save whether peer selects us as BIP152 high-bandwidth peer
+                // (receiving sendcmpct(1) signals high-bandwidth, sendcmpct(0) low-bandwidth)
+                pfrom.m_bip152_highbandwidth_from = fAnnounceUsingCMPCTBLOCK;
+            }
+            if (!State(pfrom.GetId())->fSupportsDesiredCmpctVersion) {
+                if (pfrom.GetLocalServices() & NODE_WITNESS)
+                    State(pfrom.GetId())->fSupportsDesiredCmpctVersion = (nCMPCTBLOCKVersion == 2);
+                else
+                    State(pfrom.GetId())->fSupportsDesiredCmpctVersion = (nCMPCTBLOCKVersion == 1);
+            }
+        }
+        return;
+    }
+
     // Feature negotiation of wtxidrelay must happen between VERSION and VERACK
     // to avoid relay problems from switching after a connection is up.
     if (msg_type == NetMsgType::WTXIDRELAY) {
@@ -2600,39 +2633,6 @@ void PeerManager::ProcessMessage(CNode& pfrom, const std::string& msg_type, CDat
         return;
     }
 
-    if (msg_type == NetMsgType::SENDHEADERS) {
-        LOCK(cs_main);
-        State(pfrom.GetId())->fPreferHeaders = true;
-        return;
-    }
-
-    if (msg_type == NetMsgType::SENDCMPCT) {
-        bool fAnnounceUsingCMPCTBLOCK = false;
-        uint64_t nCMPCTBLOCKVersion = 0;
-        vRecv >> fAnnounceUsingCMPCTBLOCK >> nCMPCTBLOCKVersion;
-        if (nCMPCTBLOCKVersion == 1 || ((pfrom.GetLocalServices() & NODE_WITNESS) && nCMPCTBLOCKVersion == 2)) {
-            LOCK(cs_main);
-            // fProvidesHeaderAndIDs is used to "lock in" version of compact blocks we send (fWantsCmpctWitness)
-            if (!State(pfrom.GetId())->fProvidesHeaderAndIDs) {
-                State(pfrom.GetId())->fProvidesHeaderAndIDs = true;
-                State(pfrom.GetId())->fWantsCmpctWitness = nCMPCTBLOCKVersion == 2;
-            }
-            if (State(pfrom.GetId())->fWantsCmpctWitness == (nCMPCTBLOCKVersion == 2)) { // ignore later version announces
-                State(pfrom.GetId())->fPreferHeaderAndIDs = fAnnounceUsingCMPCTBLOCK;
-                // save whether peer selects us as BIP152 high-bandwidth peer
-                // (receiving sendcmpct(1) signals high-bandwidth, sendcmpct(0) low-bandwidth)
-                pfrom.m_bip152_highbandwidth_from = fAnnounceUsingCMPCTBLOCK;
-            }
-            if (!State(pfrom.GetId())->fSupportsDesiredCmpctVersion) {
-                if (pfrom.GetLocalServices() & NODE_WITNESS)
-                    State(pfrom.GetId())->fSupportsDesiredCmpctVersion = (nCMPCTBLOCKVersion == 2);
-                else
-                    State(pfrom.GetId())->fSupportsDesiredCmpctVersion = (nCMPCTBLOCKVersion == 1);
-            }
-        }
-        return;
-    }
-
     if (msg_type == NetMsgType::INV) {
         std::vector<CInv> vInv;
         vRecv >> vInv;