Implement FDB Checksum

- Added config option `check_fdb`
- Added check in WorldServer.cpp
- Added raw MD5 function in MD5.cpp and MD5.h

dCommon/MD5.cpp

@@ -115,6 +115,14 @@ MD5::MD5(const std::string &text)
     finalize();
 }
 
+// raw md5 construstor
+MD5::MD5(const char * input, size_type length)
+{
+    init();
+    update(input, length);
+    finalize();
+}
+
 //////////////////////////////
 
 void MD5::init()

dCommon/MD5.h

@@ -54,6 +54,7 @@ public:
     
     MD5();
     MD5(const std::string& text);
+    MD5(const char * input, size_type length);
     void update(const unsigned char *buf, size_type length);
     void update(const char *buf, size_type length);
     MD5& finalize();

dWorldServer/WorldServer.cpp

@@ -838,6 +838,30 @@ void HandlePacket(Packet* packet) {
 		case MSG_WORLD_CLIENT_VALIDATION: {
 			std::string username = PacketUtils::ReadString(0x08, packet, true);
 			std::string sessionKey = PacketUtils::ReadString(74, packet, true);
+			std::string fdbChecksum = PacketUtils::ReadString(packet->length - 33, packet, false);
+
+			if (bool(std::stoi(Game::config->GetValue("check_fdb")))) {
+				std::ifstream fileStream;
+				fileStream.open ("res/CDServer.fdb", std::ios::binary | std::ios::in);
+				fileStream.seekg (0, std::ios::end);
+				uint64_t fileStreamLength = fileStream.tellg();
+				fileStream.seekg (0, std::ios::beg);
+				char * fileStreamData = new char[fileStreamLength + 1];
+				fileStream.read(fileStreamData, fileStreamLength);
+
+				*(fileStreamData + (fileStreamLength + 1)) = 0x00; // null terminate the string 
+
+				MD5 md5 = MD5(fileStreamData, fileStreamLength + 1);
+				std::string ourFdbChecksum = md5.hexdigest();
+
+				Game::logger->Log("WorldServer", "Got client checksum %s and we have server checksum %s. \n", fdbChecksum.c_str(), ourFdbChecksum.c_str());
+
+				if (fdbChecksum != ourFdbChecksum) {
+					Game::logger->Log("WorldServer", "Client checksum does not match server checksum.\n");
+					Game::server->Disconnect(packet->systemAddress, SERVER_DISCON_KICK);
+					return;
+				}
+			}
 			
 			//Request the session info from Master:
 			CBITSTREAM;

resources/worldconfig.ini

@@ -47,3 +47,6 @@ solo_racing=0
 
 # Disables the anti-speedhack system. If you get kicked randomly you might want to disable this, as it might just be lag
 disable_anti_speedhack=0
+
+# 0 or 1, check server fdb (res/CDServer.fdb) against clients
+check_fdb=0