validate serial on player join (regex)

Author: Fernando-A-Rocha

Client/mods/deathmatch/logic/CPacketHandler.cpp

@@ -570,7 +570,7 @@ void CPacketHandler::Packet_ServerDisconnected(NetBitStreamInterface& bitStream)
             break;
         case ePlayerDisconnectType::SERIAL_VERIFICATION:
             strReason = _("Disconnected: Serial verification failed");
-            strErrorCode = _E("CD44");
+            strErrorCode = _E("CD50");
             break;
         case ePlayerDisconnectType::CONNECTION_DESYNC:
             strReason = _("Disconnected: Connection desync %s");
@@ -601,6 +601,10 @@ void CPacketHandler::Packet_ServerDisconnected(NetBitStreamInterface& bitStream)
             strReason = _("Disconnected: Server shutdown or restarting");
             strErrorCode = _E("CD49");
             break;
+        case ePlayerDisconnectType::INVALID_SERIAL:
+            strReason = _("Disconnected: Invalid serial");
+            strErrorCode = _E("CD50");
+            break;
         default:
             break;
     }

Client/mods/deathmatch/logic/CPacketHandler.h

@@ -42,7 +42,8 @@ class CPacketHandler
         BAN,
         KICK,
         CUSTOM,
-        SHUTDOWN
+        SHUTDOWN,
+        INVALID_SERIAL,
     };
 
     struct SEntityDependantStuff

Server/mods/deathmatch/logic/CGame.cpp

@@ -71,6 +71,7 @@
 #include "version.h"
 #include "net/SimHeaders.h"
 #include <signal.h>
+#include <regex>
 
 #define MAX_BULLETSYNC_DISTANCE      400.0f
 #define MAX_EXPLOSION_SYNC_DISTANCE  400.0f
@@ -1781,6 +1782,18 @@ void CGame::Packet_PlayerJoinData(CPlayerJoinDataPacket& Packet)
         }
 #endif
 
+        // Prevent player from connecting if serial is invalid
+        std::regex serialRegex("^[A-F0-9]{32}$");
+        if (!std::regex_match(strSerial, serialRegex))
+        {
+            // Tell the console
+            CLogger::LogPrintf("CONNECT: %s failed to connect (Invalid serial) (%s)\n", szNick, pPlayer->GetSourceIP());
+
+            // Tell the player the problem
+            DisconnectPlayer(this, *pPlayer, CPlayerDisconnectedPacket::INVALID_SERIAL);
+            return;
+        }
+
         SString strIP = pPlayer->GetSourceIP();
         SString strIPAndSerial("IP: %s  Serial: %s  Version: %s", strIP.c_str(), strSerial.c_str(), strPlayerVersion.c_str());
         if (!CheckNickProvided(szNick))            // check the nick is valid

Server/mods/deathmatch/logic/packets/CPlayerDisconnectedPacket.h

@@ -39,7 +39,8 @@ class CPlayerDisconnectedPacket final : public CPacket
         BAN,
         KICK,
         CUSTOM,
-        SHUTDOWN
+        SHUTDOWN,
+        INVALID_SERIAL
     };
 
     CPlayerDisconnectedPacket(const char* szReason);