Launcher protocol
This launcher protocol lets you to talk to servers and get information from them, allowing you to make your own custom programs like browsers, stat tools, and so on.
Protocol information
See "article history" to look up the protocol for prior versions.
The basics
All Zandronum servers use UDP as their network protocol. Additionally, all traffic is compressed using the Huffman algorithm to save bandwidth. Refer to code in src/huffman for a standalone implementation of the Huffman encoding needed to encode/decode traffic.
There is also an implementation of the Huffman codec written in Python here. Also in Python 3 here.
Definition of data types used in this article:
- Byte: 8 bit integer
- Short: 16 bit integer
- Long: 32 bit integer
- Float: Long representation of a float
- String: null-terminated series of Bytes
Traffic is encoded in little-endian.
Getting the list of servers
This is very easy, accomplished by sending a long and a short to the master server:
Type | Value | Description |
---|---|---|
Long | 5660028 | LAUNCHER_MASTER_CHALLENGE |
Short | 2 | MASTER_SERVER_VERSION |
If your request is denied, the server will respond with one of the following:
Type | Value | Description |
---|---|---|
Long | 3 | Denied; your IP is banned (MSC_IPISBANNED) |
Long | 4 | Denied; your IP has made a request in the past 3 seconds (MSC_REQUESTIGNORED) |
Long | 5 | Denied; you're using an older version of the master protocol (MSC_WRONGVERSION) |
If you are accepted, you will receive multiple packets, each starting with:
Type | Value | Description |
---|---|---|
Long | 6 | Beginning of list (MSC_BEGINSERVERLISTPART) |
Byte | 0-255 | Packet number (starting with 0) |
Byte | 8 | Beginning of server block (MSC_SERVERBLOCK) |
Then you will get this next block, which is repeated for every IP with servers on it.
Type | Value | Description |
---|---|---|
Byte | 0-255 | n = Number of servers with this IP address |
Byte | 0-255 | IP address octet |
Byte | 0-255 | IP address octet |
Byte | 0-255 | IP address octet |
Byte | 0-255 | IP address octet |
Short | 0-65535 | IP port (sent 'n' times) |
Once the packet is full or all servers are transferred, you will receive 0 as number of servers on the next IP.
Type | Value | Description |
---|---|---|
Byte | 0 | There are no ports for the next server, i.e. no more servers in this packet. |
Finally, the response should end with either
Type | Value | Description |
---|---|---|
Byte | 2 | End of list, you got the full server list now (MSC_ENDSERVERLIST) |
or
Type | Value | Description |
---|---|---|
Byte | 7 | End of current part of the list, you'll get more packets (MSC_ENDSERVERLISTPART) |
Querying individual servers
You need to choose what data you'd like. To do so, bitshift the combination of flags with a boolean OR. For example, to get the server's name and player count, you'd use (SQF_NAME|SQF_NUMPLAYERS). Use these flags appropriately; doing so saves your users' and server hosters' bandwidth.
Query flags
Name | Value | Description |
---|---|---|
SQF_NAME | 0x00000001 | The name of the server |
SQF_URL | 0x00000002 | The associated website |
SQF_EMAIL | 0x00000004 | Contact address |
SQF_MAPNAME | 0x00000008 | Current map being played |
SQF_MAXCLIENTS | 0x00000010 | Maximum amount of clients who can connect to the server |
SQF_MAXPLAYERS | 0x00000020 | Maximum amount of players who can join the game (the rest must spectate) |
SQF_PWADS | 0x00000040 | PWADs loaded by the server |
SQF_GAMETYPE | 0x00000080 | Game type code |
SQF_GAMENAME | 0x00000100 | Game mode name |
SQF_IWAD | 0x00000200 | The IWAD used by the server |
SQF_FORCEPASSWORD | 0x00000400 | Whether or not the server enforces a password |
SQF_FORCEJOINPASSWORD | 0x00000800 | Whether or not the server enforces a join password |
SQF_GAMESKILL | 0x00001000 | The skill level on the server |
SQF_BOTSKILL | 0x00002000 | The skill level of any bots on the server |
SQF_DMFLAGS | 0x00004000 | (Deprecated) The values of dmflags, dmflags2 and compatflags. Use SQF_ALL_DMFLAGS instead. |
SQF_LIMITS | 0x00010000 | Timelimit, fraglimit, etc. |
SQF_TEAMDAMAGE | 0x00020000 | Team damage factor. |
SQF_TEAMSCORES | 0x00040000 | (Deprecated) The scores of the red and blue teams. Use SQF_TEAMINFO_* instead. |
SQF_NUMPLAYERS | 0x00080000 | Amount of players currently on the server. |
SQF_PLAYERDATA | 0x00100000 | Information of each player in the server. |
SQF_TEAMINFO_NUMBER | 0x00200000 | Amount of teams available. |
SQF_TEAMINFO_NAME | 0x00400000 | Names of teams. |
SQF_TEAMINFO_COLOR | 0x00800000 | RGB colors of teams. |
SQF_TEAMINFO_SCORE | 0x01000000 | Scores of teams. |
SQF_TESTING_SERVER | 0x02000000 | Whether or not the server is a testing server, also the name of the testing binary. |
SQF_DATA_MD5SUM | 0x04000000 | (Deprecated) Used to retrieve the MD5 checksum of skulltag_data.pk3, now obsolete and returns an empty string instead. |
SQF_ALL_DMFLAGS | 0x08000000 | Values of various dmflags used by the server. |
SQF_SECURITY_SETTINGS | 0x10000000 | Security setting values (for now only whether the server enforces the master banlist) |
SQF_OPTIONAL_WADS | 0x20000000 | Which PWADs are optional |
SQF_DEH | 0x40000000 | List of DEHACKED patches loaded by the server. |
SQF_EXTENDED_INFO | 0x80000000 | Additional server information, see the table below for more information. |
Extended flags
Name | Value | Description |
---|---|---|
SQF2_PWAD_HASHES | 0x00000001 | The MD5 hashes of the server's loaded PWADs. |
SQF2_COUNTRY | 0x00000002 | The server's ISO 3166-1 alpha-3 country code. |
SQF2_GAMEMODE_NAME | 0x00000004 | (development version 3.2-alpha and above only) The name of the server's current game mode. |
SQF2_GAMEMODE_SHORTNAME | 0x00000008 | (development version 3.2-alpha and above only) The short name of the server's current game mode. |
Segmented challenge
(development version 3.2-alpha and above only)
This challenge is only available on servers running Zandronum 3.2 or newer. For backwards compatibility, the old #Old protocol is still supported and can also request a segmented response, but is now deprecated. It is recommended that launchers prefer this new challenge when 3.2 reaches widespread adoption and fall back to the old challenge.
Type | Value | Description |
---|---|---|
Long | 200 | Launcher challenge |
Long | Flags | Desired information |
Long | Time | Current time, this will be sent back to you so you can determine ping. |
Long | Flags2 | The extended information you want. Ensure you specify SQF_EXTENDED_INFO in the normal Flags field as well. |
The server will respond with a Long, which will be one of the following:
Symbol | Value | Description |
---|---|---|
SERVER_LAUNCHER_IGNORING | 5660024 | Denied; your IP has made a request in the past sv_queryignoretime seconds |
SERVER_LAUNCHER_BANNED | 5660025 | Denied; your IP is banned |
SERVER_LAUNCHER_SEGMENTED_CHALLENGE | 5660031 | Accepted; segmented information follows |
If you were denied, this response is followed by another Long, which is the time you sent to the server.
Old protocol challenge
Send the server the following packet:
Type | Value | Description |
---|---|---|
Long | 199 | Launcher challenge |
Long | Flags | Desired information |
Long | Time | Current time, this will be sent back to you so you can determine ping. |
Long | Flags2 | Optional. The extended information you want. Ensure you specify SQF_EXTENDED_INFO in the normal Flags field as well. |
Byte | Segmented | Optional. Set this to 1 to indicate that you want a segmented response. This exists for backwards compatibility with older servers. |
The server will respond with a Long, which will be one of the following:
Symbol | Value | Description |
---|---|---|
SERVER_LAUNCHER_CHALLENGE | 5660031 | Accepted; server information follows |
SERVER_LAUNCHER_IGNORING | 5660024 | Denied; your IP has made a request in the past sv_queryignoretime seconds |
SERVER_LAUNCHER_BANNED | 5660025 | Denied; your IP is banned |
SERVER_LAUNCHER_SEGMENTED_CHALLENGE | 5660031 | Accepted; segmented information follows |
Segmented protocol response
If you asked for a segmented response, and the server supports it, you'll get:
Type | Value | Description |
---|---|---|
Byte | Segment | Segment number. If the most significant bit is set, then this is the last segment. |
Short | Size | The uncompressed size of this packet. |
After this, segment 0 also includes:
Type | Value | Description |
---|---|---|
Long | Time | The time you sent to the server. |
String | Version | Server version string with revision number. |
Each field set returned then contains the following information before the actual data.
Type | Value | Description |
---|---|---|
Byte | Fieldset | The field set this packet contains data for (0 -> SQF_, 1 -> SQF2_) |
Long | Flags | The fields contained in this packet. |
Single packet response
If you didn't ask for a segmented response, or the server doesn't support segmented packets, you'll get:
Type | Value | Description |
---|---|---|
Long | Time | The time you sent to the server. |
String | Version | Server version string with revision number. |
Long | Flags | The info you'll be receiving, possibly corrected (see below). |
Field data
Field data is sent in the order the fields appear in the table below. The server will automatically correct your request if you made a mistake (like request team scores in cooperative games), so always use the flags it sends back to you when reading your data.
Flag set 0 (SQF_)
Type | Flag | Description |
---|---|---|
String | SQF_NAME | The server's name (sv_hostname) |
String | SQF_URL | The server's WAD URL (sv_website) |
String | SQF_EMAIL | The server host's e-mail (sv_hostemail) |
String | SQF_MAPNAME | The current map's name |
Byte | SQF_MAXCLIENTS | The max number of clients (sv_maxclients) |
Byte | SQF_MAXPLAYERS | The max number of players (sv_maxplayers) |
Byte | SQF_PWADS | The number of PWADs loaded |
String | SQF_PWADS | The PWAD's name (Sent for each PWAD) |
Byte | SQF_GAMETYPE | The current game mode. See below. |
Byte | SQF_GAMETYPE | Instagib - true (1) / false (0) |
Byte | SQF_GAMETYPE | Buckshot - true (1) / false (0) |
String | SQF_GAMENAME | The base game's name ("DOOM", "DOOM II", "HERETIC", "HEXEN", "ERROR!") |
String | SQF_IWAD | The IWAD's name |
Byte | SQF_FORCEPASSWORD | Whether a password is required to join the server (sv_forcepassword) |
Byte | SQF_FORCEJOINPASSWORD | Whether a password is required to join the game (sv_forcejoinpassword) |
Byte | SQF_GAMESKILL | The game's difficulty (skill) |
Byte | SQF_BOTSKILL | The bot difficulty (botskill) |
Long | SQF_DMFLAGS | [Deprecated] Value of dmflags |
Long | SQF_DMFLAGS | [Deprecated] Value of dmflags2 |
Long | SQF_DMFLAGS | [Deprecated] Value of compatflags |
Short | SQF_LIMITS | Value of fraglimit |
Short | SQF_LIMITS | Value of timelimit |
Short | SQF_LIMITS | time left in minutes (only sent if timelimit > 0) |
Short | SQF_LIMITS | duellimit |
Short | SQF_LIMITS | pointlimit |
Short | SQF_LIMITS | winlimit |
Float | SQF_TEAMDAMAGE | The team damage scalar (teamdamage) |
Short | SQF_TEAMSCORES | [Deprecated] Blue team's fragcount/wincount/score |
Short | SQF_TEAMSCORES | [Deprecated] Red team's fragcount/wincount/score |
Byte | SQF_NUMPLAYERS | The number of players in the server |
Byte | SQF_PLAYERDATA | Segmented only: Whether the team field for each player is sent. Unlike all other fields for SQF_PLAYERDATA, this is only sent once, and not for each player. |
String | SQF_PLAYERDATA | Player's name |
Short | SQF_PLAYERDATA | Player's pointcount/fragcount/killcount |
Short | SQF_PLAYERDATA | Player's ping |
Byte | SQF_PLAYERDATA | Player is spectating - true (1) / false (0) |
Byte | SQF_PLAYERDATA | Player is a bot - true (1) / false (0) |
Byte | SQF_PLAYERDATA | Player's team (returned on team games, 255 is no team) |
Byte | SQF_PLAYERDATA | Player's time on the server, in minutes. Note: SQF_PLAYERDATA information is sent once for each player on the server. |
Byte | SQF_TEAMINFO_NUMBER | The number of teams used. |
String | SQF_TEAMINFO_NAME | The team's name. (Sent for each team.) |
Long | SQF_TEAMINFO_COLOR | The team's color. (Sent for each team.) |
Short | SQF_TEAMINFO_SCORE | The team's score. (Sent for each team.) |
Byte | SQF_TESTING_SERVER | Whether this server is running a testing binary - true (1) / false (0) |
String | SQF_TESTING_SERVER | An empty string in case the server is running a stable binary, otherwise name of the testing binary archive found in http://www.skulltag.com/testing/files/ |
String | SQF_DATA_MD5SUM | [Deprecated] Returns an empty string. |
Byte | SQF_ALL_DMFLAGS | The number of flags that will be sent. |
Long | SQF_ALL_DMFLAGS | The value of the flags (Sent for each flag in the order dmflags, dmflags2, zadmflags, compatflags, zacompatflags, compatflags2) |
Byte | SQF_SECURITY_SETTINGS | Whether the server is enforcing the master ban list - true (1) / false (0) The other bits of this byte may be used to transfer other security related settings in the future. |
Byte | SQF_OPTIONAL_WADS | Amount of optional wad indices that follow |
Byte | SQF_OPTIONAL_WADS | Index number int the list sent with SQF_PWADS - this wad is optional (sent for each optional Wad) |
Byte | SQF_DEH | Amount of deh patches loaded |
String | SQF_DEH | Deh patch name (one string for each deh patch) |
Byte | SQF_EXTENDED_INFO | Segmented protocol: The next flag set you will receive. |
Long | SQF_EXTENDED_INFO | Segmented protocol: The flags specifying the information from the next flag set that immediately follows.
Old protocol: The flags specifying the SQF2_data that immediately follows. |
Flag set 1 (SQF2_)
Type | Flag | Description |
---|---|---|
Byte | SQF2_PWAD_HASHES | The number of hashes sent. |
String | SQF2_PWAD_HASHES | The hash of the PWAD, sent for each PWAD. The indices are the same as sent in SQF_PWADS |
Byte[3] | SQF2_COUNTRY | The server's ISO 3166-1 alpha-3 country code. This is sent as a raw char array of 3 length, there is no null terminator. Zandronum also has two special values for this field, XIP and XUN. See #Country codes below for how to handle this field. |
String | SQF2_GAMEMODE_NAME | (development version 3.2-alpha and above only) The name of the server's current game mode, as defined in the GAMEMODE lump. |
String | SQF2_GAMEMODE_SHORTNAME | (development version 3.2-alpha and above only) The short name of the server's current game mode, as defined in the GAMEMODE lump. |
Notes
Game modes
Game modes are defined as:
0 GAMEMODE_COOPERATIVE 1 GAMEMODE_SURVIVAL 2 GAMEMODE_INVASION 3 GAMEMODE_DEATHMATCH 4 GAMEMODE_TEAMPLAY 5 GAMEMODE_DUEL 6 GAMEMODE_TERMINATOR 7 GAMEMODE_LASTMANSTANDING 8 GAMEMODE_TEAMLMS 9 GAMEMODE_POSSESSION 10 GAMEMODE_TEAMPOSSESSION 11 GAMEMODE_TEAMGAME 12 GAMEMODE_CTF 13 GAMEMODE_ONEFLAGCTF 14 GAMEMODE_SKULLTAG 15 GAMEMODE_DOMINATION
Country codes
Zandronum 3.1 introduces the ability to server hosts to specify the country their server is located in via a new CVAR, sv_country. This was introduced to allow hosts to combat the inaccuracies of IP geolocation that launchers rely on. This value is specified to launchers via the new SQF2_COUNTRY field, which can have the following values:
- an ISO 3166-1 alpha-3 country code. Note that Zandronum doesn't validate whether the country code supplied in sv_country is a registered country code. If the launcher does not recognise the given code, then it should display the server's country as unknown.
- the value XIP, which suggests to the launcher that it should attempt IP geolocation to determine the server's country. The default value of sv_country will cause it to return this by default, to preserve existing behaviour and make it easier for casual hosts. If geolocation is unsupported, disabled, or fails, then the server's country should be displayed as unknown.
- the value XUN, in which case the launcher should display the server's country as unknown.
Also see Issue 3894: Allow servers to present their country to launchers.
Examples
Basic segmented example
In this example we query a simple co-operative server for some basic information.
Request
Type | Value | Description |
---|---|---|
Long | 200 | The launcher challenge. |
Long | 1234 | Ping value. |
Long | 36700161 | The fields from set 0 we want: SQF_NAME|SQF_PLAYERDATA|SQF_TEAMINFO_NUMBER|SQF_TESTING_SERVER |
Long | 6 | The fields from set 1 we want: SQF2_COUNTRY|SQF2_GAMEMODE_NAME |
Response
Type | Value | Description |
---|---|---|
Long | 5660031 | The server's response, indicating we're getting a segmented response packet. |
Byte | 177 | The segment number. The most significant bit is set, as this is the final and only packet. Clear the MSB to reveal this is packet 0: 128 & ~0x80 = 0. |
Short | 143 | Size of this packet in bytes. |
Long | 1234 | The ping value we sent before, sent only in segment 0. |
String | 3.2-alpha-r230430-1741 on Linux 5.15.0-69-generic | The server version, sent only in segment 0. |
Byte | 0 | The initial flag set being sent. |
Long | 35127297 | The initial flags from that set being sent: SQF_NAME|SQF_NUMPLAYERS|SQF_PLAYERDATA|SQF_TESTING_SERVER|SQF_EXTENDED_INFO. Observe how:
|
String | Skipper Pavilion | From SQF_NAME. The server's name. |
Byte | 1 | From SQF_NUMPLAYERS. The number of players online. |
Byte | 0 | From SQF_PLAYERDATA. Whether the team field will be sent for players. |
String | Alphus | From SQF_PLAYERDATA. The name of the first player in the server. |
Short | 0 | From SQF_PLAYERDATA. Alphus' score. |
Short | 0 | From SQF_PLAYERDATA. Alphus' ping. |
Byte | 0 | From SQF_PLAYERDATA. Whether Alphus is a spectator or not. |
Byte | 1 | From SQF_PLAYERDATA. Whether Alphus is a bot or not. |
Byte | 5 | From SQF_PLAYERDATA. How many minutes Alphus has been in the server. |
Byte | 1 | From SQF_TESTING_SERVER. Whether the server is running a testing binary. |
String | downloads/testing/3.2/ZandroDev3.2-230430-1741windows.zip | From SQF_TESTING_SERVER. Path to the testing binary on zandronum.com. |
Byte | 1 | From SQF_EXTENDED_INFO. The flag set that follows. |
Long | 6 | From SQF_EXTENDED_INFO. The fields that follow from that set: SQF2_COUNTRY|SQF2_GAMEMODE_NAME |
char[3] | GBR | From SQF2_COUNTRY. The country code the server presents, as set by sv_country. |
String | Cooperative | From SQF2_GAMEMODE_NAME. The name of the game mode currently being played. |
Example code
This uses a loop to handle switching flag sets in the middle of a segment.
function handleFields() {
while (readOffset < packetLength) {
const fieldsetNum = readByte();
const flags = readLong();
if (fieldsetNum == 0) {
if (flags & SQF_NAME) {
const name = readString();
}
if (flags & SQF_URL) {
const url = readString();
}
// ...
}
else if (fieldsetNum == 1) {
if (flags & SQF2_PWAD_HASHES) {
const numHashes = readByte();
for (let i = 0; i < numHashes; i++) {
const hash = readString();
}
}
// ...
}
if (!(flags & SQF_EXTENDED_INFO)) {
break;
}
}
}
A variation that can be used with the old single-packet protocol:
function handleFields() {
let fieldsetNum = 0;
let flags = 0;
while (readOffset < packetLength) {
fieldsetNum = segmented ? readByte() : fieldsetNum;
flags = readLong();
if (fieldsetNum == 0) {
// ...
}
else if (fieldsetNum == 1) {
// ...
}
if (flags & SQF_EXTENDED_INFO) {
fieldsetNum++;
} else {
break;
}
}
}