Check if another player has the same serial (#3854)

Author: Nico8340

Client/mods/deathmatch/logic/CPacketHandler.cpp

@@ -572,6 +572,10 @@ void CPacketHandler::Packet_ServerDisconnected(NetBitStreamInterface& bitStream)
             strReason = _("Disconnected: Serial verification failed");
             strErrorCode = _E("CD44");
             break;
+        case ePlayerDisconnectType::SERIAL_DUPLICATE:
+            strReason = _("Disconnected: Serial already in use");
+            strErrorCode = _E("CD50");
+            break;
         case ePlayerDisconnectType::CONNECTION_DESYNC:
             strReason = _("Disconnected: Connection desync %s");
             strErrorCode = _E("CD45");

Client/mods/deathmatch/logic/CPacketHandler.h

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

Server/mods/deathmatch/editor.conf

@@ -268,6 +268,12 @@
           Values: 0 - Off, 1 - Enabled.  Default - 1 -->
     <resource_client_file_checks>1</resource_client_file_checks>
 
+    <!-- This parameter determines that the server checks when the players connect that there are no other players with the same serial number. 
+         Note that this may break compatibility with virtual machines.
+         Not guarantees that the player cannot manipulate their serial.
+         Values: 0 - Off, 1 - Enabled.  Default - 1 -->
+    <check_duplicate_serials>1</check_duplicate_serials>
+
     <!-- Specifies the module(s) which are loaded with the server. To load several modules, add more <module>
          parameter(s). Optional parameter. -->
     <!-- <module src="sample_win32.dll"/> -->

Server/mods/deathmatch/local.conf

@@ -274,6 +274,12 @@
          Values: 0 - Off, 1 - Enabled.  Default - 0 -->
     <elementdata_whitelisted>0</elementdata_whitelisted>
 
+    <!-- This parameter determines that the server checks when the players connect that there are no other players with the same serial number. 
+         Note that this may break compatibility with virtual machines.
+         Not guarantees that the player cannot manipulate their serial.
+         Values: 0 - Off, 1 - Enabled.  Default - 1 -->
+    <check_duplicate_serials>1</check_duplicate_serials>
+
     <!-- Specifies the module(s) which are loaded with the server. To load several modules, add more <module>
          parameter(s). Optional parameter. -->
     <!-- <module src="sample_win32.dll"/> -->

Server/mods/deathmatch/logic/CGame.cpp

@@ -1798,6 +1798,21 @@ void CGame::Packet_PlayerJoinData(CPlayerJoinDataPacket& Packet)
             return;
         }
 
+        // Check if another player is using the same serial
+        if (m_pMainConfig->IsCheckDuplicateSerialsEnabled() && m_pPlayerManager->GetBySerial(strSerial))
+        {
+            // Tell the console
+            CLogger::LogPrintf("CONNECT: %s failed to connect (Serial already in use) (%s)\n", szNick, strIPAndSerial.c_str());
+
+            // Tell the player the problem
+            if (pPlayer->CanBitStream(eBitStreamVersion::CheckDuplicateSerials))
+                DisconnectPlayer(this, *pPlayer, CPlayerDisconnectedPacket::SERIAL_DUPLICATE);
+            else
+                DisconnectPlayer(this, *pPlayer, CPlayerDisconnectedPacket::KICK);
+
+            return;
+        }
+
         // Check the nick is valid
         if (!CheckNickProvided(szNick))
         {

Server/mods/deathmatch/logic/CMainConfig.cpp

@@ -80,6 +80,7 @@ CMainConfig::CMainConfig(CConsole* pConsole) : CXMLConfig(NULL)
     m_iBackupAmount = 5;
     m_bSyncMapElementData = true;
     m_elementDataWhitelisted = false;
+    m_checkDuplicateSerials = true;
 }
 
 bool CMainConfig::Load()
@@ -528,6 +529,7 @@ bool CMainConfig::Load()
     }
 
     GetBoolean(m_pRootNode, "elementdata_whitelisted", m_elementDataWhitelisted);
+    GetBoolean(m_pRootNode, "check_duplicate_serials", m_checkDuplicateSerials);
 
     ApplyNetOptions();
 

Server/mods/deathmatch/logic/CMainConfig.h

@@ -127,6 +127,7 @@ class CMainConfig : public CXMLConfig
     bool                        IsDatabaseCredentialsProtectionEnabled() const { return m_bDatabaseCredentialsProtectionEnabled != 0; }
     bool                        IsFakeLagCommandEnabled() const { return m_bFakeLagCommandEnabled != 0; }
     bool                        IsElementDataWhitelisted() const { return m_elementDataWhitelisted; }
+    bool                        IsCheckDuplicateSerialsEnabled() const noexcept { return m_checkDuplicateSerials; }
     bool                        IsCheckResourceClientFilesEnabled() const noexcept { return m_checkResourceClientFiles != 0; }
 
     SString GetSetting(const SString& configSetting);
@@ -230,5 +231,6 @@ class CMainConfig : public CXMLConfig
     int                        m_iPlayerTriggeredEventIntervalMs;
     int                        m_iMaxPlayerTriggeredEventsPerInterval;
     bool                       m_elementDataWhitelisted;
+    bool                       m_checkDuplicateSerials;
     int                        m_checkResourceClientFiles;
 };

Server/mods/deathmatch/logic/CPlayerManager.cpp

@@ -138,6 +138,17 @@ CPlayer* CPlayerManager::Get(const char* szNick, bool bCaseSensitive)
     return NULL;
 }
 
+CPlayer* CPlayerManager::GetBySerial(const std::string_view serial) const noexcept
+{
+    for (const auto& player : m_Players)
+    {
+        if (player->GetSerial() == serial)
+            return player;
+    }
+
+    return nullptr;
+}
+
 void CPlayerManager::DeleteAll()
 {
     // Delete all the items in the list

Server/mods/deathmatch/logic/CPlayerManager.h

@@ -40,6 +40,7 @@ class CPlayerManager
 
     CPlayer* Get(const NetServerPlayerID& PlayerSocket);
     CPlayer* Get(const char* szNick, bool bCaseSensitive = false);
+    CPlayer* GetBySerial(const std::string_view serial) const noexcept;
 
     std::list<CPlayer*>::const_iterator IterBegin() { return m_Players.begin(); };
     std::list<CPlayer*>::const_iterator IterEnd() { return m_Players.end(); };

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

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