Name of the folder containing the game files. Note: Both SiN 1 Multiplayer and Rag Doll Kung Fu utilise this response protocol. NOTE:changed 13:05:43 :when l4d2 server received some packet from same ip address,it may deined replay This change was introduced in December 2020 to address the reflection attack vulnerability, and all clients are encouraged to support the new protocol. In that case, the client should repeat the request by appending the challenge number. Instead, the server may reply with a challenge to the client using S2C_CHALLENGE ('A' or 0x41).
However, since this reply is larger than the request, it makes the server vulnerable to a reflection amplification attack. Servers may respond with the data immediately. NOTE: In the future, additional data may be appended to the request! Do not assume that if a request has extra data, that it is a bogus packet! L4d2 server 2.2.1.3 update:some server will send challenge number ,it caused hlsw cant get server info Ĥ-byte challenge (sometimes - see below)įF FF FF FF 54 53 6F 75 72 63 65 20 45 6E 67 69 ÿÿÿÿTSource EngiįF FF FF FF 54 53 6F 75 72 63 65 20 45 6E 67 69 6E 65 20 51 75 65 72 79 00 0A 08 5E EA Retrieves information about the server including, but not limited to: its name, the map currently being played, and the number of players. Queries should be sent in UDP packets to the listen port of the server. (DEPRECATED) A2S_SERVERQUERY_GETCHALLENGE Returns a challenge number for use in the player and rules query. A2S_PLAYER Details about each player on the server. So by reading the first 4 bytes you can decide whether the data is split (-2) or in one packet (-1).Ī2S_INFO Basic information about the server. Compression appears to have been phased out in newer Source games, but is still present in ~2006-era engines.īecause UDP packets can arrive in different order or delayed, every packet should be verified by its "ID" and "Number"! Every request or response with or without this header is continued with an integer -1 (0xFFFFFFFF) and the user data. To uncompress this response: collect and assemble all the payloads of the received packets, then pass that into a function like BZ2_bzBuffToBuffDecompress() in C, bzdecompress() in PHP, or bz2.decompress() in Python. Size of the whole response once it is decompressed. This is only present in the first packet of the response and only if the response is being compressed. AppIDs which are known not to contain this field: 215, 17550, 17700, and 240 when protocol = 7. For older engine versions: the maximum and minimum size of the packet was unchangeable. The default value is 1248 bytes (0x04E0), but the server administrator can decrease this. ( Orange Box Engine and above only.) Maximum size of packet before packet switching occurs. The total number of packets in the response.
However, if the most significant bit is 1, then the response was compressed with bzip2 before being cut and sent. Upper 4 bits represent the number of the current packet (starting at 0) and bottom 4 bits represent the total number of packets (2 to 15). Unique number assigned by server per answer. Multi-packet Response Format Goldsource Server DataĪlways equal to -2 (0xFFFFFFFE). If a request or response needs more packets for the data it starts the packets with an additional header.Īlways equal to -1 (0xFFFFFFFF).
Steam uses a packet size of 1400 bytes + IP/UDP headers. Variable-length byte field, encoded in UTF-8, terminated by 0x00 Java users should use ByteBuffer to convert. All types are little endian, which is the default on most languages on x86 CPUs. All server queries consist of five basic types of data packed together into a data stream.