View source for Master Server Query Protocol

=Client to master server=
Send the following UDP query to a master server to get a list of Source host servers.

==Format==
{|
! Type || Field || Value
|-
| [[Byte]] || Message Type || 0x31 - the character "1"
|-
| [[Byte]] || Region Code || See below
|- 
| [[Bytes]] x 4 || IP || See below
|-
| [[String Zero]] || Filter || See below
|}

===Region Codes===
The region of the world that you wish to find servers in.
{|
! Byte || Description
|-
| 0x00 || US East coast
|-
| 0x01 || US West coast
|-
| 0x02 || South America
|-
| 0x03 || Europe
|-
| 0x04 || Asia
|-
| 0x05 || Australia
|-
| 0x06 || Middle East
|-
| 0x07 || Africa
|-
| 0xFF || Rest of the world
|}
<!--What's for none? = world-->

===IP===

The first IP Steam sends is 4 0's

From then on, IP becomes the last IP received in the master servers reply. This allows steam to then grab another list of more servers.

===Filter===
Allows you to restrict the results to servers running a certain game, map, etc.

Send an empty string (0x00) to recieve a list of all types of servers.

Insert <code>\</code> in between filter parameters
*<code>\type\d</code>
::Servers running dedicated
*<code>\secure\1</code>
::Servers using anti-cheat technology (VAC)
*<code>\gamedir\[mod]</code>
::Servers running the specified modification (ex. cstrike)
*<code>\map\[map]</code>
::Servers running the specified map (ex. cs_italy)
*<code>\linux\1</code>
::Servers running on a Linux platform
*<code>\empty\1</code>
::Servers that are not empty
*<code>\full\1</code>
::Servers that are not full
*<code>\proxy\1</code>
::Servers that are spectator proxies

===Sample Query===
<pre>
31 0 0 0 0 0 0
</pre>

To get all servers on the east coast

==Master Servers==
Current master servers are

'''[[Goldsource]]:'''
* 69.28.151.162:27010
* 207.173.177.11:27010
* 68.142.72.250:27010

'''[[Source]]:'''
* 68.142.72.250:27011
* 69.28.151.162:27011

'''[[Rag Doll Kung Fu]]:'''
* 207.173.177.12:27012
* 207.173.177.11:27012

'''[[SiN 1 Multiplayer]]:'''
* 69.28.151.162:27010

If you can, get your application to check the file <code>Steam\config\masterservers.vdf</code> to get the latest list of master servers.



==Reply Format==
The reply always starts with <code>FF FF FF FF 66 0A</code>.

The format is then a series of these server address blocks:
{|
! Type || Data
|-
| [[Byte]] || First octet of IP address
|-
| [[Byte]] || Second octet of IP address
|-
| [[Byte]] || Third octet of IP address
|-
| [[Byte]] || Fourth octet of IP address
|-
| Unsigned [[Short]] || Port number - usually 27015 (<code>69 87</code>) - this is '''network ordered''', which is unlike every other Steam protocol.
|}

Some of the servers may be unreachable, so query each server directly to find out. Note also that this list is not exhaustive, so if you're looking for a particular type of server make sure that you specify a filter with the query, rather than filtering client side.

=Game server to master server=
==Join==
Shortly after a game server has been initialized, it picks two master servers to "join." In order for clients to see a particular game server when they click on the "Internet" tab, the game server must be present in the Steam master servers' records.

The game server sends each master server "q" (<code>71</code>).

The master servers each respond by sending <code>FF FF FF FF 73 0A</code> followed by a (relatively) unique 4-byte "challenge" number.

==Challenge response==
After receiving the challenge packet, the game server then sends its challenge information in the following format:
===Goldsource===
<pre>002a                                 30 0a 5c 70 72 6f            0.\pro
0030   74 6f 63 6f 6c 5c 34 37 5c 63 68 61 6c 6c 65 6e  tocol\47\challen
0040   67 65 5c 31 33 33 39 38 39 35 37 30 32 5c 70 6c  ge\1339895702\pl
0050   61 79 65 72 73 5c 30 5c 6d 61 78 5c 32 5c 62 6f  ayers\0\max\2\bo
0060   74 73 5c 30 5c 67 61 6d 65 64 69 72 5c 63 73 74  ts\0\gamedir\cst
0070   72 69 6b 65 5c 6d 61 70 5c 64 65 5f 64 75 73 74  rike\map\de_dust
0080   5c 74 79 70 65 5c 64 5c 70 61 73 73 77 6f 72 64  \type\d\password
0090   5c 30 5c 6f 73 5c 6c 5c 73 65 63 75 72 65 5c 30  \0\os\l\secure\0
00a0   5c 6c 61 6e 5c 30 5c 76 65 72 73 69 6f 6e 5c 31  \lan\0\version\1
00b0   2e 31 2e 32 2e 35 2f 53 74 64 69 6f 5c 72 65 67  .1.2.5/Stdio\reg
00c0   69 6f 6e 5c 32 35 35 5c 70 72 6f 64 75 63 74 5c  ion\255\product\
00d0   63 73 74 72 69 6b 65 0a                          cstrike.</pre>

The challenge number, 1339895702 (<code>0x4FDD2F96</code>) in this example, is the reverse of the challenge number originally sent by the server (<code>96 2F DD 4F</code>).

===Source===
<pre>002a                                 30 0a 5c 70 72 6f            0.\pro
0030   74 6f 63 6f 6c 5c 37 5c 63 68 61 6c 6c 65 6e 67  tocol\7\challeng
0040   65 5c 31 33 33 39 36 31 38 32 33 5c 70 6c 61 79  e\133961823\play
0050   65 72 73 5c 30 5c 6d 61 78 5c 32 5c 62 6f 74 73  ers\0\max\2\bots
0060   5c 30 5c 67 61 6d 65 64 69 72 5c 63 73 74 72 69  \0\gamedir\cstri
0070   6b 65 5c 6d 61 70 5c 64 65 5f 64 75 73 74 5c 70  ke\map\de_dust\p
0080   61 73 73 77 6f 72 64 5c 30 5c 6f 73 5c 6c 5c 6c  assword\0\os\l\l
0090   61 6e 5c 30 5c 72 65 67 69 6f 6e 5c 32 35 35 5c  an\0\region\255\
00a0   74 79 70 65 5c 64 5c 73 65 63 75 72 65 5c 30 5c  type\d\secure\0\
00b0   76 65 72 73 69 6f 6e 5c 31 2e 30 2e 30 2e 32 38  version\1.0.0.28
00c0   5c 70 72 6f 64 75 63 74 5c 63 73 74 72 69 6b 65  \product\cstrike
00d0   0a                                               .</pre>

The challenge number, 133961823 (<code>0x07FC185F</code>) in this example, is the reverse of the challenge number originally sent by the server (<code>5F 18 FC 07</code>).

===Differences===
The field order is a bit different with Source than with Goldsource.
{| class="wikitable"
! Goldsource
| protocol || challenge || players || max || bots || gamedir || map || <font style="color:#FF0000;">type</font> || <font style="color:#FF0000;">password</font> || <font style="color:#FF0000;">os</font> || <font style="color:#FF0000;">secure</font> || <font style="color:#FF0000;">lan</font> || <font style="color:#FF0000;">version</font> || <font style="color:#FF0000;">region</font> || product
|-
! Source
| protocol || challenge || players || max || bots || gamedir || map || <font style="color:#FF0000;">password</font> || <font style="color:#FF0000;">os</font> || <font style="color:#FF0000;">lan</font> || <font style="color:#FF0000;">region</font> || <font style="color:#FF0000;">type</font> || <font style="color:#FF0000;">secure</font> || <font style="color:#FF0000;">version</font> || product
|-
|}


==Heartbeat==
A "heartbeat" occurs every five minutes in order to let the master servers know that a game server is still "alive." The game server simply goes through the process of "joining" the master server list again.

==Quit==

===Goldsource===
The game server sends the master server <code>62 0A</code> to signal that the game server has shut down.

===Source===
The game server sends the master server <code>62 0A 00</code> to signal that the game server has shut down.

=See Also=
* [[Source Server Queries]]
[[Category:Programming]][[Category:Technical]]