net: Disallow sending messages until the version handshake is complete

This is a change in behavior, though it's much more sane now than before.

src/net_processing.cpp

@@ -1277,7 +1277,6 @@ bool static ProcessMessage(CNode* pfrom, std::string strCommand, CDataStream& vR
         // Change version
         pfrom->SetSendVersion(nSendVersion);
         pfrom->nVersion = nVersion;
-        pfrom->fSuccessfullyConnected = true;
 
         if((nServices & NODE_WITNESS))
         {
@@ -1387,6 +1386,7 @@ bool static ProcessMessage(CNode* pfrom, std::string strCommand, CDataStream& vR
             nCMPCTBLOCKVersion = 1;
             connman.PushMessage(pfrom, msgMaker.Make(NetMsgType::SENDCMPCT, fAnnounceUsingCMPCTBLOCK, nCMPCTBLOCKVersion));
         }
+        pfrom->fSuccessfullyConnected = true;
     }
 
 
@@ -2725,8 +2725,8 @@ bool SendMessages(CNode* pto, CConnman& connman, std::atomic<bool>& interruptMsg
 {
     const Consensus::Params& consensusParams = Params().GetConsensus();
     {
-        // Don't send anything until we get its version message
+        // Don't send anything until the version handshake is complete
-        if (pto->nVersion == 0 || pto->fDisconnect)
+        if (!pto->fSuccessfullyConnected || pto->fDisconnect)
             return true;
 
         // If we get here, the outgoing message serialization version is set and can't change.

src/test/DoS_tests.cpp

@@ -55,6 +55,7 @@ BOOST_AUTO_TEST_CASE(DoS_banning)
     dummyNode1.SetSendVersion(PROTOCOL_VERSION);
     GetNodeSignals().InitializeNode(&dummyNode1, *connman);
     dummyNode1.nVersion = 1;
+    dummyNode1.fSuccessfullyConnected = true;
     Misbehaving(dummyNode1.GetId(), 100); // Should get banned
     SendMessages(&dummyNode1, *connman, interruptDummy);
     BOOST_CHECK(connman->IsBanned(addr1));
@@ -65,6 +66,7 @@ BOOST_AUTO_TEST_CASE(DoS_banning)
     dummyNode2.SetSendVersion(PROTOCOL_VERSION);
     GetNodeSignals().InitializeNode(&dummyNode2, *connman);
     dummyNode2.nVersion = 1;
+    dummyNode2.fSuccessfullyConnected = true;
     Misbehaving(dummyNode2.GetId(), 50);
     SendMessages(&dummyNode2, *connman, interruptDummy);
     BOOST_CHECK(!connman->IsBanned(addr2)); // 2 not banned yet...
@@ -85,6 +87,7 @@ BOOST_AUTO_TEST_CASE(DoS_banscore)
     dummyNode1.SetSendVersion(PROTOCOL_VERSION);
     GetNodeSignals().InitializeNode(&dummyNode1, *connman);
     dummyNode1.nVersion = 1;
+    dummyNode1.fSuccessfullyConnected = true;
     Misbehaving(dummyNode1.GetId(), 100);
     SendMessages(&dummyNode1, *connman, interruptDummy);
     BOOST_CHECK(!connman->IsBanned(addr1));
@@ -110,6 +113,7 @@ BOOST_AUTO_TEST_CASE(DoS_bantime)
     dummyNode.SetSendVersion(PROTOCOL_VERSION);
     GetNodeSignals().InitializeNode(&dummyNode, *connman);
     dummyNode.nVersion = 1;
+    dummyNode.fSuccessfullyConnected = true;
 
     Misbehaving(dummyNode.GetId(), 100);
     SendMessages(&dummyNode, *connman, interruptDummy);