net: move nLocalHostNonce to CConnman

This behavior seems to have been quite racy and broken.

Move nLocalHostNonce into CNode, and check received nonces against all
non-fully-connected nodes. If there's a match, assume we've connected
to ourself.

src/main.cpp

@@ -5025,7 +5025,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         }
 
         // Disconnect if we connected to ourself
-        if (nNonce == nLocalHostNonce && nNonce > 1)
+        if (pfrom->fInbound && !connman.CheckIncomingNonce(nNonce))
         {
             LogPrintf("connected to self at %s, disconnecting\n", pfrom->addr.ToString());
             pfrom->fDisconnect = true;

src/net.cpp

@@ -83,7 +83,6 @@ CCriticalSection cs_mapLocalHost;
 std::map<CNetAddr, LocalServiceInfo> mapLocalHost;
 static bool vfLimited[NET_MAX] = {};
 static CNode* pnodeLocalHost = NULL;
-uint64_t nLocalHostNonce = 0;
 int nMaxConnections = DEFAULT_MAX_PEER_CONNECTIONS;
 std::string strSubVersion;
 
@@ -346,6 +345,16 @@ CNode* CConnman::FindNode(const CService& addr)
     return NULL;
 }
 
+bool CConnman::CheckIncomingNonce(uint64_t nonce)
+{
+    LOCK(cs_vNodes);
+    BOOST_FOREACH(CNode* pnode, vNodes) {
+        if (!pnode->fSuccessfullyConnected && !pnode->fInbound && pnode->GetLocalNonce() == nonce)
+            return false;
+    }
+    return true;
+}
+
 CNode* CConnman::ConnectNode(CAddress addrConnect, const char *pszDest, bool fCountFailure)
 {
     if (pszDest == NULL) {
@@ -465,7 +474,6 @@ void CNode::PushVersion()
     int64_t nTime = (fInbound ? GetAdjustedTime() : GetTime());
     CAddress addrYou = (addr.IsRoutable() && !IsProxy(addr) ? addr : CAddress(CService(), addr.nServices));
     CAddress addrMe = GetLocalAddress(&addr);
-    GetRandBytes((unsigned char*)&nLocalHostNonce, sizeof(nLocalHostNonce));
     if (fLogIPs)
         LogPrint("net", "send version message: version %d, blocks=%d, us=%s, them=%s, peer=%d\n", PROTOCOL_VERSION, nBestHeight, addrMe.ToString(), addrYou.ToString(), id);
     else
@@ -2535,6 +2543,8 @@ CNode::CNode(NodeId idIn, SOCKET hSocketIn, const CAddress& addrIn, const std::s
     nextSendTimeFeeFilter = 0;
     id = idIn;
 
+    GetRandBytes((unsigned char*)&nLocalHostNonce, sizeof(nLocalHostNonce));
+
     BOOST_FOREACH(const std::string &msg, getAllNetMessageTypes())
         mapRecvBytesPerMsgCmd[msg] = 0;
     mapRecvBytesPerMsgCmd[NET_MESSAGE_COMMAND_OTHER] = 0;

src/net.h

@@ -114,6 +114,7 @@ public:
     void Stop();
     bool BindListenPort(const CService &bindAddr, std::string& strError, bool fWhitelisted = false);
     bool OpenNetworkConnection(const CAddress& addrConnect, bool fCountFailure, CSemaphoreGrant *grantOutbound = NULL, const char *strDest = NULL, bool fOneShot = false, bool fFeeler = false);
+    bool CheckIncomingNonce(uint64_t nonce);
 
     bool ForNode(NodeId id, std::function<bool(CNode* pnode)> func);
     bool ForEachNode(std::function<bool(CNode* pnode)> func);
@@ -297,7 +298,6 @@ extern bool fListen;
 extern ServiceFlags nLocalServices;
 extern ServiceFlags nRelevantServices;
 extern bool fRelayTxes;
-extern uint64_t nLocalHostNonce;
 
 /** Maximum number of connections to simultaneously allow (aka connection slots) */
 extern int nMaxConnections;
@@ -523,12 +523,17 @@ private:
 
     static uint64_t CalculateKeyedNetGroup(const CAddress& ad);
 
+    uint64_t nLocalHostNonce;
 public:
 
     NodeId GetId() const {
       return id;
     }
 
+    uint64_t GetLocalNonce() const {
+      return nLocalHostNonce;
+    }
+
     int GetRefCount()
     {
         assert(nRefCount >= 0);