net: deserialize the entire version message locally

This avoids having some vars set if the version negotiation fails.

Also copy it all into CNode at the same site. nVersion and
fSuccessfullyConnected are set last, as they are the gates for the other vars.
Make them atomic for that reason.

src/net.h

@@ -627,7 +627,7 @@ public:
     const CAddress addr;
     std::string addrName;
     CService addrLocal;
-    int nVersion;
+    std::atomic<int> nVersion;
     // strSubVer is whatever byte array we read from the wire. However, this field is intended
     // to be printed out, displayed to humans in various forms and so on. So we sanitize it and
     // store the sanitized version in cleanSubVer. The original should be used when dealing with
@@ -639,7 +639,7 @@ public:
     bool fAddnode;
     bool fClient;
     const bool fInbound;
-    bool fSuccessfullyConnected;
+    std::atomic_bool fSuccessfullyConnected;
     std::atomic_bool fDisconnect;
     // We use fRelayTxes for two purposes -
     // a) it allows us to not relay tx invs before receiving the peer's version message

src/net_processing.cpp

@@ -1199,16 +1199,23 @@ bool static ProcessMessage(CNode* pfrom, std::string strCommand, CDataStream& vR
         CAddress addrFrom;
         uint64_t nNonce = 1;
         uint64_t nServiceInt;
+        ServiceFlags nServices;
         int nVersion;
+        int nSendVersion;
+        std::string strSubVer;
+        int nStartingHeight = -1;
+        bool fRelay = true;
+
         vRecv >> nVersion >> nServiceInt >> nTime >> addrMe;
-        pfrom->nServices = ServiceFlags(nServiceInt);
+        nSendVersion = std::min(nVersion, PROTOCOL_VERSION);
+        nServices = ServiceFlags(nServiceInt);
         if (!pfrom->fInbound)
         {
-            connman.SetServices(pfrom->addr, pfrom->nServices);
+            connman.SetServices(pfrom->addr, nServices);
         }
-        if (pfrom->nServicesExpected & ~pfrom->nServices)
+        if (pfrom->nServicesExpected & ~nServices)
         {
-            LogPrint("net", "peer=%d does not offer the expected services (%08x offered, %08x expected); disconnecting\n", pfrom->id, pfrom->nServices, pfrom->nServicesExpected);
+            LogPrint("net", "peer=%d does not offer the expected services (%08x offered, %08x expected); disconnecting\n", pfrom->id, nServices, pfrom->nServicesExpected);
             connman.PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::REJECT, strCommand, REJECT_NONSTANDARD,
                                strprintf("Expected to offer services %08x", pfrom->nServicesExpected)));
             pfrom->fDisconnect = true;
@@ -1230,20 +1237,13 @@ bool static ProcessMessage(CNode* pfrom, std::string strCommand, CDataStream& vR
         if (!vRecv.empty())
             vRecv >> addrFrom >> nNonce;
         if (!vRecv.empty()) {
-            vRecv >> LIMITED_STRING(pfrom->strSubVer, MAX_SUBVERSION_LENGTH);
-            pfrom->cleanSubVer = SanitizeString(pfrom->strSubVer);
+            vRecv >> LIMITED_STRING(strSubVer, MAX_SUBVERSION_LENGTH);
         }
         if (!vRecv.empty()) {
-            vRecv >> pfrom->nStartingHeight;
+            vRecv >> nStartingHeight;
         }
-        {
-            LOCK(pfrom->cs_filter);
-            if (!vRecv.empty())
-                vRecv >> pfrom->fRelayTxes; // set to true after we get the first filter* message
-            else
-                pfrom->fRelayTxes = true;
-        }
-
+        if (!vRecv.empty())
+            vRecv >> fRelay;
         // Disconnect if we connected to ourself
         if (pfrom->fInbound && !connman.CheckIncomingNonce(nNonce))
         {
@@ -1252,7 +1252,6 @@ bool static ProcessMessage(CNode* pfrom, std::string strCommand, CDataStream& vR
             return true;
         }
 
-        pfrom->addrLocal = addrMe;
         if (pfrom->fInbound && addrMe.IsRoutable())
         {
             SeenLocal(addrMe);
@@ -1262,9 +1261,25 @@ bool static ProcessMessage(CNode* pfrom, std::string strCommand, CDataStream& vR
         if (pfrom->fInbound)
             PushNodeVersion(pfrom, connman, GetAdjustedTime());
 
-        pfrom->fClient = !(pfrom->nServices & NODE_NETWORK);
+        connman.PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::VERACK));
+
+        pfrom->nServices = nServices;
+        pfrom->addrLocal = addrMe;
+        pfrom->strSubVer = strSubVer;
+        pfrom->cleanSubVer = SanitizeString(strSubVer);
+        pfrom->nStartingHeight = nStartingHeight;
+        pfrom->fClient = !(nServices & NODE_NETWORK);
+        {
+            LOCK(pfrom->cs_filter);
+            pfrom->fRelayTxes = fRelay; // set to true after we get the first filter* message
+        }
+
+        // Change version
+        pfrom->SetSendVersion(nSendVersion);
+        pfrom->nVersion = nVersion;
+        pfrom->fSuccessfullyConnected = true;
 
-        if((pfrom->nServices & NODE_WITNESS))
+        if((nServices & NODE_WITNESS))
         {
             LOCK(cs_main);
             State(pfrom->GetId())->fHaveWitness = true;
@@ -1276,12 +1291,6 @@ bool static ProcessMessage(CNode* pfrom, std::string strCommand, CDataStream& vR
         UpdatePreferredDownload(pfrom, State(pfrom->GetId()));
         }
 
-        // Change version
-        connman.PushMessage(pfrom, CNetMsgMaker(INIT_PROTO_VERSION).Make(NetMsgType::VERACK));
-        int nSendVersion = std::min(nVersion, PROTOCOL_VERSION);
-        pfrom->nVersion = nVersion;
-        pfrom->SetSendVersion(nSendVersion);
-
         if (!pfrom->fInbound)
         {
             // Advertise our address
@@ -1309,8 +1318,6 @@ bool static ProcessMessage(CNode* pfrom, std::string strCommand, CDataStream& vR
             connman.MarkAddressGood(pfrom->addr);
         }
 
-        pfrom->fSuccessfullyConnected = true;
-
         std::string remoteAddr;
         if (fLogIPs)
             remoteAddr = ", peeraddr=" + pfrom->addr.ToString();
@@ -1352,7 +1359,7 @@ bool static ProcessMessage(CNode* pfrom, std::string strCommand, CDataStream& vR
 
     if (strCommand == NetMsgType::VERACK)
     {
-        pfrom->SetRecvVersion(std::min(pfrom->nVersion, PROTOCOL_VERSION));
+        pfrom->SetRecvVersion(std::min(pfrom->nVersion.load(), PROTOCOL_VERSION));
 
         if (!pfrom->fInbound) {
             // Mark this node as currently connected, so we update its timestamp later.