limit total length of user agent comments

Reworked-By: Wladimir J. van der Laan <laanwj@gmail.com>

src/init.cpp

@@ -1206,6 +1206,13 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
 
     RegisterNodeSignals(GetNodeSignals());
 
+    // format user agent, check total size
+    strSubVersion = FormatSubVersion(CLIENT_NAME, CLIENT_VERSION, mapMultiArgs.count("-uacomment") ? mapMultiArgs["-uacomment"] : std::vector<string>());
+    if (strSubVersion.size() > MAX_SUBVERSION_LENGTH) {
+        return InitError(strprintf("Total length of network version string %i exceeds maximum of %i characters. Reduce the number and/or size of uacomments.",
+            strSubVersion.size(), MAX_SUBVERSION_LENGTH));
+    }
+
     if (mapArgs.count("-onlynet")) {
         std::set<enum Network> nets;
         BOOST_FOREACH(const std::string& snet, mapMultiArgs["-onlynet"]) {

src/main.cpp

@@ -4768,7 +4768,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         if (!vRecv.empty())
             vRecv >> addrFrom >> nNonce;
         if (!vRecv.empty()) {
-            vRecv >> LIMITED_STRING(pfrom->strSubVer, 256);
+            vRecv >> LIMITED_STRING(pfrom->strSubVer, MAX_SUBVERSION_LENGTH);
             pfrom->cleanSubVer = SanitizeString(pfrom->strSubVer);
         }
         if (!vRecv.empty())

src/net.cpp

@@ -73,6 +73,7 @@ static std::vector<ListenSocket> vhListenSocket;
 CAddrMan addrman;
 int nMaxConnections = DEFAULT_MAX_PEER_CONNECTIONS;
 bool fAddressesInitialized = false;
+std::string strSubVersion;
 
 vector<CNode*> vNodes;
 CCriticalSection cs_vNodes;
@@ -435,7 +436,7 @@ void CNode::PushVersion()
     else
         LogPrint("net", "send version message: version %d, blocks=%d, us=%s, peer=%d\n", PROTOCOL_VERSION, nBestHeight, addrMe.ToString(), id);
     PushMessage("version", PROTOCOL_VERSION, nLocalServices, nTime, addrYou, addrMe,
-                nLocalHostNonce, FormatSubVersion(CLIENT_NAME, CLIENT_VERSION, mapMultiArgs.count("-uacomment") ? mapMultiArgs["-uacomment"] : std::vector<string>()), nBestHeight, true);
+                nLocalHostNonce, strSubVersion, nBestHeight, true);
 }
 
 

src/net.h

@@ -49,6 +49,8 @@ static const unsigned int MAX_INV_SZ = 50000;
 static const unsigned int MAX_ADDR_TO_SEND = 1000;
 /** Maximum length of incoming protocol messages (no message over 2 MiB is currently acceptable). */
 static const unsigned int MAX_PROTOCOL_MESSAGE_LENGTH = 2 * 1024 * 1024;
+/** Maximum length of strSubVer in `version` message */
+static const unsigned int MAX_SUBVERSION_LENGTH = 256;
 /** -listen default */
 static const bool DEFAULT_LISTEN = true;
 /** The maximum number of entries in mapAskFor */
@@ -156,6 +158,9 @@ extern CCriticalSection cs_vAddedNodes;
 extern NodeId nLastNodeId;
 extern CCriticalSection cs_nLastNodeId;
 
+/** Subversion as sent to the P2P network in `version` messages */
+extern std::string strSubVersion;
+
 struct LocalServiceInfo {
     int nScore;
     int nPort;

src/rpcnet.cpp

@@ -469,8 +469,7 @@ UniValue getnetworkinfo(const UniValue& params, bool fHelp)
 
     UniValue obj(UniValue::VOBJ);
     obj.push_back(Pair("version",       CLIENT_VERSION));
-    obj.push_back(Pair("subversion",
-        FormatSubVersion(CLIENT_NAME, CLIENT_VERSION, mapMultiArgs.count("-uacomment") ? mapMultiArgs["-uacomment"] : std::vector<string>())));
+    obj.push_back(Pair("subversion",    strSubVersion));
     obj.push_back(Pair("protocolversion",PROTOCOL_VERSION));
     obj.push_back(Pair("localservices",       strprintf("%016x", nLocalServices)));
     obj.push_back(Pair("timeoffset",    GetTimeOffset()));