engine: server: implement simple anti-speedhack

engine/server/server.h

@@ -80,6 +80,8 @@ extern int SV_UPDATE_BACKUP;
 #define FCL_SEND_RESOURCES	BIT( 9 )
 #define FCL_FORCE_UNMODIFIED	BIT( 10 )
 
+#define MAX_CLIENT_IGNORECMDTIME_WARNS 10 // just a random number (for now)
+
 typedef enum
 {
 	ss_dead,		// no map loaded
@@ -258,6 +260,9 @@ typedef struct sv_client_s
 	int		userid;			// identifying number on server
 	int		extensions;
 	char		useragent[MAX_INFO_STRING];
+
+	int ignorecmdtime_warns; // how many times client time was faster than server during this session
+	qboolean ignorecmdtime_warned; // did we warn our server operator in the log for this batch of commands?
 } sv_client_t;
 
 /*
@@ -443,6 +448,7 @@ extern convar_t		coop;
 extern convar_t		sv_cheats;
 extern convar_t		public_server;
 extern convar_t		sv_nat;
+extern convar_t		sv_speedhack_kick;
 
 extern	convar_t		*sv_pausable;		// allows pause in multiplayer
 extern	convar_t		*sv_check_errors;

engine/server/sv_main.c

@@ -59,6 +59,7 @@ CVAR_DEFINE_AUTO( sv_log_onefile, "0", FCVAR_ARCHIVE, "logs server information t
 CVAR_DEFINE_AUTO( sv_trace_messages, "0", FCVAR_LATCH, "enable server usermessages tracing (good for developers)" );
 CVAR_DEFINE_AUTO( sv_master_response_timeout, "4", FCVAR_ARCHIVE, "master server heartbeat response timeout in seconds" );
 CVAR_DEFINE_AUTO( sv_autosave, "1", FCVAR_ARCHIVE|FCVAR_SERVER|FCVAR_PRIVILEGED, "enable autosaving" );
+CVAR_DEFINE_AUTO( sv_speedhack_kick, "1", FCVAR_ARCHIVE, "enable automatic kicking players who use speedhacks" );
 
 // game-related cvars
 CVAR_DEFINE_AUTO( mapcyclefile, "mapcycle.txt", 0, "name of multiplayer map cycle configuration file" );
@@ -919,6 +920,8 @@ void SV_Init( void )
 	Cvar_RegisterVariable( &sv_enttools_enable );
 	Cvar_RegisterVariable( &sv_enttools_maxfire );
 
+	Cvar_RegisterVariable( &sv_speedhack_kick );
+
 	sv_allow_joystick = Cvar_Get( "sv_allow_joystick", "1", FCVAR_ARCHIVE, "allow connect with joystick enabled" );
 	sv_allow_mouse = Cvar_Get( "sv_allow_mouse", "1", FCVAR_ARCHIVE, "allow connect with mouse" );
 	sv_allow_touch = Cvar_Get( "sv_allow_touch", "1", FCVAR_ARCHIVE, "allow connect with touch controls" );

engine/server/sv_pmove.c

@@ -911,11 +911,23 @@ void SV_RunCmd( sv_client_t *cl, usercmd_t *ucmd, int random_seed )
 
 	if( cl->ignorecmdtime > host.realtime )
 	{
+		if( !cl->ignorecmdtime_warned )
+		{
+			// report to server op
+			Con_Reportf( S_WARN "%s time is faster than server time (speed hack?)\n", cl->name );
+			cl->ignorecmdtime_warned = true;
+			cl->ignorecmdtime_warns++;
+
+			// automatically kick player
+			if( sv_speedhack_kick.value && cl->ignorecmdtime_warns > MAX_CLIENT_IGNORECMDTIME_WARNS )
+				SV_KickPlayer( cl, "Speed hacks aren't allowed on this server" );
+		}
 		cl->cmdtime += ((double)ucmd->msec / 1000.0 );
 		return;
 	}
 
 	cl->ignorecmdtime = 0.0;
+	cl->ignorecmdtime_warned = false;
 
 	// chop up very long commands
 	if( cmd.msec > 50 )