fix buffer overflow and format string bug in auth server response

processing

code/qcommon/net_chan.c

@@ -719,7 +719,7 @@ void QDECL NET_OutOfBandPrint( netsrc_t sock, netadr_t adr, const char *format,
 	string[3] = -1;
 
 	va_start( argptr, format );
-	vsprintf( string+4, format, argptr );
+	vsnprintf( string+4, sizeof(string)-4, format, argptr );
 	va_end( argptr );
 
 	// send the datagram