Server Queries The Source engine allows you to query information from a running game server using UDP/IP packets. This document describes the packet formats and protocol to access this data. Basic Data Types All server queries consist of 5 basic types of data packed together into a data stream. All types are little endian. Name Description byte 8 bit character short 16 bit signed integer long 32 bit signed integer float 32 bit float value string variable length byte field, terminated by 0x00 Query Types The server responds to 4 queries: ⢠A2S_SERVERQUERY_GETCHALLENGE - Returns a challenge number for use in the player and rules query. ⢠A2S_INFO - Basic information about the server. ⢠A2S_PLAYER - Details about each player on the server. ⢠A2S_RULES - The rules the server is using. Queries should be sent in UDP packets to the listen port of the server, which is typically port 27015. A2S_SERVERQUERY_GETCHALLENGE Request format Challenge values are required for A2S_PLAYER and A2S_RULES requests, you can use this request to get one. Note: You can also send A2S_PLAYER and A2S_RULES queries with a challenge value of -1 (0xFF FF FF FF FF FF FF FF) and they will respond with a challenge value to use (using the reply format below). FF FF FF FF 57 Reply format Data Type Comment Type byte Should be equal to 'A' (0x41) Challenge long The challenge number to use Example reply: FF FF FF FF FF 41 32 42 59 45 53 93 43 71 A2S_INFO Request format Server info can be requested by sending the following byte values in a UDP packet to the server. FF FF FF FF 54 53 6F 75 72 63 65 20 45 6E 67 69 6E 65 20 51 75 65 72 79 00 Reply format Data Type Comment Type byte Should be equal to 'I' (0x49) Version byte Network version Hostname string The Servers name Map string The current map being played Game Directory string The Game type Game string A friendly string name for the game type Description AppID short Steam Application number (currently always set to 0) Num players byte The number of players currently on the server Max players byte Maximum allowed players for the server Num of bots byte Number of bot players currently on the server Dedicated byte Set to 1 for dedicated servers OS byte 'l' for Linux, 'w' for Windows Password byte If set to 1 a password is required to join this server Secure byte If set to 1 this server is running VAC Game Version string The version of the game Example reply: FF FF FF FF 49 02 67 61 6D 65 32 78 73 2E 63 6F ....I.game2xs.co 6D 20 43 6F 75 6E 74 65 72 2D 53 74 72 69 6B 65 m.Counter-Strike 20 53 6F 75 72 63 65 20 23 31 00 64 65 5F 64 75 .Source.#1.de_du 73 74 00 63 73 74 72 69 6B 65 00 43 6F 75 6E 74 st.cstrike.Count 65 72 2D 53 74 72 69 6B 65 00 00 00 0B 28 00 64 er-Strike....(.d 6C 00 00 31 2e 31 2e 30 2e 31 36 00 l..1.1.0.16 A2S_PLAYER Request format FF FF FF FF 55 <4 byte challenge number> The challenge number can either be set to -1 (0xFF FF FF FF FF FF FF FF) to have the server reply with S2C_CHALLENGE, or use the value from a previous A2S_SERVERQUERY_GETCHALLENGE request. Reply format The players response has two sections, the initial header: Data Type Comment Type byte Should be equal to 'D' (0x44) Num Players byte The number of players reported in this response Then for each player the following fields are sent: Data Type Comment Index byte The index into [0.. Num Players] for this entry Player Name string Player's name Kills long Number of kills this player has Time connected float The time in seconds this player has been connected A2S_RULES Request format FF FF FF FF 56 <4 byte challenge number> The challenge number can either be set to -1 (0xFF FF FF FF FF FF FF FF) to have the server reply with S2C_CHALLENGE, or use the value from a previous A2S_SERVERQUERY_GETCHALLENGE request. Reply format The rules response has two sections, the initial header: Data Type Comment Type byte Should be equal to 'E' (0x45) Num Rules short The number of rules reported in this response Then for each rule the following fields are sent: Data Type Comment Rule Name string The name of the rule Rule Value string The rules value âââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââââ (C) 2004 Valve Corporation. All rights reserved. Valve, the Valve logo, Half-Life, the Half-Life logo, the Lambda logo, Steam, the Steam logo, Team Fortress, the Team Fortress logo, Opposing Force, Day of Defeat, the Day of Defeat logo, Counter-Strike, the Counter-Strike logo, Source, the Source logo, Hammer and Counter-Strike: Condition Zero are trademarks and/or registered trademarks of Valve Corporation. Microsoft and Visual Studio are trademarks and/or registered trademarks of Microsoft Corporation. All other trademarks are property of their respective owners.