Protocol Classes

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Protocol Classes#

This covers the Sans-I/O interface provided by little-a2s.

Protocols#

class little_a2s.A2SClientProtocol(*, challenge=-1)#

Bases: object

Implements the client-side protocol for A2S.

This follows the Source format. For the Goldsource equivalent, see A2SGoldsourceClientProtocol.

Parameters:

challenge (int) – The challenge sequence to use for requests. This can change dynamically when receiving S2C_CHALLENGE responses.

Changed in version 0.7.0: Removed the packets_to_send() method.

events_received()#

Return a list of events received since this last call.

Return type:

list[ClientEvent]

info()#

Create an A2S_INFO packet to send to the server.

Return type:

ClientPacketInfo

invalidate_response(id)#

Invalidate an incomplete multi-part response with the given ID.

This should be invoked after some sort of timeout.

Parameters:

id (int)

Return type:

MultiPartResponse | None

players()#

Create an A2S_PLAYER packet to send to the server.

Return type:

ClientPacketPlayers

receive_datagram(data)#

Process a packet from the server.

Raises:

PayloadError – The data is malformed.

Parameters:

data (bytes)

Return type:

None

rules()#

Create an A2S_RULES packet to send to the server.

Return type:

ClientPacketRules

class little_a2s.A2SGoldsourceClientProtocol(*, challenge=-1)#

Bases: A2SClientProtocol

The Goldsource variant of the A2S client protocol used by older games.

Changed in version 0.2.0: Renamed to A2SGoldsourceClientProtocol from A2SClientGoldsourceProtocol.

Parameters:

challenge (int)

events_received()#

Return a list of events received since this last call.

Return type:

list[ClientEvent]

info()#

Create an A2S_INFO packet to send to the server.

Return type:

ClientPacketInfo

invalidate_response(id)#

Invalidate an incomplete multi-part response with the given ID.

This should be invoked after some sort of timeout.

Parameters:

id (int)

Return type:

MultiPartResponse | None

players()#

Create an A2S_PLAYER packet to send to the server.

Return type:

ClientPacketPlayers

receive_datagram(data)#

Process a packet from the server.

Raises:

PayloadError – The data is malformed.

Parameters:

data (bytes)

Return type:

None

rules()#

Create an A2S_RULES packet to send to the server.

Return type:

ClientPacketRules

Events#

class little_a2s.Event#

Bases: object

The base class for all A2S protocol events.

class little_a2s.ClientEvent#

Bases: Event

An A2S client protocol event.

class little_a2s.ClientEventChallenge(*, challenge)#

Bases: ClientEvent

An S2C_CHALLENGE client protocol event.

Parameters:

challenge (int)

classmethod from_reader(reader)#

Parse this class from a reader.

Parameters:

reader (Reader)

Return type:

Self

challenge: int#

The challenge number to append to subsequent requests.

class little_a2s.ClientEventGoldsourceInfo(*, address, name, map, folder, game, players, max_players, protocol, type, environment, visibility, mod, vac, bots)#

Bases: ClientEvent

An A2S_INFO Goldsource client protocol event.

Parameters:
classmethod from_reader(reader)#

Parse this class from a reader.

Parameters:

reader (Reader)

Return type:

Self

address: str#

IP address and port of the server.

bots: int#

Number of bots on the server.

environment: Environment#

Indicates the operating system of the server.

folder: str#

Name of the folder containing the game files.

game: str#

Full name of the game.

map: str#

Map the server has currently loaded.

max_players: int#

Maximum number of players the server reports it can hold.

mod: GoldsourceMod | None#

Information about the Goldsource mod, if the game is a mod.

name: str#

Name of the server.

players: int#

Number of players on the server.

protocol: int#

Protocol version used by the server.

type: ServerType#

Indicates the type of server.

vac: VAC#

Specifies whether the server uses Valve Anti Cheat.

visibility: Visibility#

Indicates whether the server requires a password.

class little_a2s.ClientEventInfo(*, protocol, name, map, folder, game, id, players, max_players, bots, type, environment, visibility, vac, version, extra)#

Bases: ClientEvent

An A2S_INFO client protocol event.

This follows the Source format. For the Goldsource equivalent, see ClientEventGoldsourceInfo.

Parameters:
classmethod from_reader(reader)#

Parse this class from a reader.

Parameters:

reader (Reader)

Return type:

Self

bots: int#

Number of bots on the server.

environment: Environment#

Indicates the operating system of the server.

extra: ExtraInfo | None#

Extra data included with the response.

folder: str#

Name of the folder containing the game files.

game: str#

Full name of the game.

id: int#

Steam Application ID of game.

map: str#

Map the server has currently loaded.

max_players: int#

Maximum number of players the server reports it can hold.

name: str#

Name of the server.

players: int#

Number of players on the server.

protocol: int#

Protocol version used by the server.

type: ServerType#

Indicates the type of server.

vac: VAC#

Specifies whether the server uses Valve Anti Cheat.

version: str#

Version of the game installed on the server.

visibility: Visibility#

Indicates whether the server requires a password.

class little_a2s.ClientEventPlayers(*, players)#

Bases: ClientEvent, Sequence[Player]

An A2S_PLAYER client protocol event.

Changed in version 0.5.1: Added support for the sequence protocol to interact with the underlying list of players.

Parameters:

players (list[Player])

classmethod from_reader(reader)#

Parse this class from a reader.

Parameters:

reader (Reader)

Return type:

Self

count(value) → integer -- return number of occurrences of value#
index(value[, start[, stop]]) → integer -- return first index of value.#

Raises ValueError if the value is not present.

Supporting start and stop arguments is optional, but recommended.

players: list[Player]#

List of players whose information was gathered.

class little_a2s.ClientEventRules(*, rules)#

Bases: ClientEvent, Mapping[bytes, bytes]

An A2S_RULES client protocol event.

Changed in version 0.5.1: Added support for the mapping protocol to interact with the underlying dictionary of rules.

Parameters:

rules (dict[bytes, bytes])

classmethod from_reader(reader)#

Parse this class from a reader.

Parameters:

reader (Reader)

Return type:

Self

decode()#

Return all rules decoded with UTF-8.

Return type:

dict[str, str]

get(k[, d]) → D[k] if k in D, else d.  d defaults to None.#
items() → a set-like object providing a view on D's items#
keys() → a set-like object providing a view on D's keys#
values() → an object providing a view on D's values#
rules: dict[bytes, bytes]#

The server rules or configuration variables.

While the protocol states these should be UTF-8 strings, some games might provide binary data in rules which may not decode correctly as UTF-8. If you know the game doesn’t do this, you can use the decode() method for convenience.

class little_a2s.Environment(*values)#

Bases: _EnumReprMixin, IntEnum

Indicates the operating system of the server.

class little_a2s.ExtraInfo(*, port=None, steam_id=None, spectator_port=None, spectator_name=None, keywords=None, game_id=None)#

Bases: object

Extra data included with an A2S_INFO response.

Parameters:
classmethod from_reader(reader, flag)#

Parse this class from a reader.

Parameters:

  • reader (Reader) – The reader to consume.

  • flag (int) – The Extra Data Flag (EDF) indicating which fields are included.

Return type:

Self

game_id: int | None = None#

The server’s game ID.

keywords: str | None = None#

Tags that describe the game according to the server.

port: int | None = None#

The server’s game port number.

spectator_name: str | None = None#

The name of the spectator server for SourceTV.

spectator_port: int | None = None#

The spectator port number for SourceTV.

steam_id: int | None = None#

The server’s steam ID.

class little_a2s.GoldsourceMod(*, link, download_link, version, size, type, dll)#

Bases: object

Information about the Goldsource mod, if the game is a mod.

Parameters:
classmethod from_reader(reader)#

Parse this class from a reader.

Parameters:

reader (Reader)

Return type:

Self

dll: GoldsourceModDLL#

Indicates whether the mod uses its own DLL.

URL to download the mod. May be empty.

URL to mod website. May be empty.

size: int#

Space (in bytes) the mod takes up.

type: GoldsourceModType#

Indicates the type of mod.

version: int#

Version of mod installed on server.

class little_a2s.GoldsourceModDLL(*values)#

Bases: _EnumReprMixin, IntEnum

Indicates whether a GoldsourceMod uses its own DLL.

EXTENSION = 1#

This mod provides its own DLL.

NATIVE = 0#

This mod uses the Half-Life DLL.

class little_a2s.GoldsourceModType(*values)#

Bases: _EnumReprMixin, IntEnum

Indicates the type of mod for GoldsourceMod.

class little_a2s.Player(*, index, name, score, duration)#

Bases: object

A player returned in the A2S_PLAYER response.

Parameters:
duration: float#

Time (in seconds) player has been connected to the server.

index: int#

Index of player.

name: str#

Name of the player.

score: int#

Player’s score, such as kills.

class little_a2s.ServerType(*values)#

Bases: _EnumReprMixin, IntEnum

Indicates the type of server.

class little_a2s.VAC(*values)#

Bases: _EnumReprMixin, IntEnum

Specifies whether the server uses Valve Anti Cheat.

class little_a2s.Visibility(*values)#

Bases: _EnumReprMixin, IntEnum

Indicates whether the server requires a password.

Headers#

class little_a2s.Header#

Bases: object

An A2S response header.

class little_a2s.HeaderType(*values)#

Bases: _EnumReprMixin, IntEnum

MULTI = -2#

Means the response is split.

SIMPLE = -1#

Means the response isn’t split.

class little_a2s.SimpleHeader#

Bases: Header

An single-packet A2S response header.

class little_a2s.MultiHeader(*, id, current, total, size, compressed)#

Bases: Header

A multi-packet A2S response header for Source games.

Parameters:
compressed: Compression | None#

An optional compression header. Mostly present in ~2006-era engines.

current: int#

The number of the packet.

id: int#

Unique number assigned by server per answer.

size: int#

The maximum size of packet before packet switching occurs, usually 1248 bytes.

total: int#

The total number of packets in the response.

class little_a2s.Compression(*, size, checksum)#

Bases: object

The compression header for Source games. Mostly present in ~2006-era engines.

Parameters:
checksum: int#

CRC32 checksum of uncompressed response.

size: int#

Size of the whole response once it is decompressed.

class little_a2s.MultiGoldsourceHeader(*, id, current, total)#

Bases: Header

A multi-packet A2S response header for Goldsource games.

Parameters:
current: int#

The number of the packet.

id: int#

Unique number assigned by server per answer.

total: int#

The total number of packets in the response.

Packets#

class little_a2s.Packet#

Bases: object

The base class of all A2S packets.

class little_a2s.ClientPacket(*, header, payload, challenge)#

Bases: Packet

An A2S packet sent by the client.

This class and its subclasses can be coerced into byte streams by passing to bytes(), for example bytes(packet).

Parameters:
challenge: int#

The challenge number last given by the server.

header: bytes#

The header of the request.

payload: bytes#

The payload of the request.

class little_a2s.ClientPacketInfo(*, challenge=-1)#

Bases: ClientPacket

An A2S_INFO packet sent by the client.

Parameters:

challenge (int)

challenge: int = -1#

The challenge number last given by the server.

header: bytes = b'\xff\xff\xff\xffT'#

The header of the request.

payload: bytes = b'Source Engine Query\x00'#

The payload of the request.

class little_a2s.ClientPacketPlayers(*, challenge=-1)#

Bases: ClientPacket

An A2S_PLAYER packet sent by the client.

Parameters:

challenge (int)

challenge: int = -1#

The challenge number last given by the server.

header: bytes = b'\xff\xff\xff\xffU'#

The header of the request.

payload: bytes = b''#

The payload of the request.

class little_a2s.ClientPacketRules(*, challenge=-1)#

Bases: ClientPacket

An A2S_RULES packet sent by the client.

Parameters:

challenge (int)

challenge: int = -1#

The challenge number last given by the server.

header: bytes = b'\xff\xff\xff\xffV'#

The header of the request.

payload: bytes = b''#

The payload of the request.

Utilities#

class little_a2s.MultiPartResponse(*, id, total, compressed, payloads=<factory>)#

Bases: object

A multi-part response waiting to be assembled.

Changed in version 0.2.0: Removed the current attribute.

Parameters:
add(header, payload)#

Add a payload with the given header to the response.

Raises:

PayloadError – The data is malformed.

Parameters:
Return type:

None

assemble()#

Assemble the payload together if all parts have been received.

Raises:

PayloadError – The data is malformed.

Return type:

bytes | None

compressed: Compression | None#

An optional compression header. Mostly present in ~2006-era engines.

id: int#

Unique number assigned by server per answer.

payloads: dict[int, bytes]#

A sequenced mapping of payloads to be assembled.

total: int#

The total number of packets in the response.

class little_a2s.Readable(*args, **kwargs)#

Bases: Protocol

read(n=-1, /)#

Read up to n bytes, or the entire stream if n is negative.

Parameters:

n (int)

Return type:

bytes

class little_a2s.Reader(data)#

Bases: object

A simple reader for parsing serialized data.

Parameters:

data (bytes | Readable)

read(n=-1, /)#

Read exactly n bytes, or the entire stream if n is negative.

Raises:

EOFError – Not enough bytes could be read.

Parameters:

n (int)

Return type:

bytes

read_byte()#

Read a single unsigned byte.

Raises:

EOFError – Not enough bytes could be read.

Return type:

int

read_char()#

Read a single ASCII character.

Raises:

EOFError – Not enough bytes could be read.

Return type:

str

read_float()#

Read a 32-bit float.

Raises:

EOFError – Not enough bytes could be read.

Return type:

float

read_long()#

Read a signed 32-bit integer.

Raises:

EOFError – Not enough bytes could be read.

Return type:

int

read_null()#

Read a null byte.

Raises:
Return type:

Literal[0]

read_null_string()#

Read a null-terminated byte string.

Raises:

EOFError – Not enough bytes could be read.

Return type:

bytes

read_null_utf8()#

Read a null-terminated, UTF-8 decoded string.

Raises:
Return type:

str

read_short()#

Read a signed 16-bit integer.

Raises:

EOFError – Not enough bytes could be read.

Return type:

int

read_uint64()#

Read an unsigned 64-bit integer.

Raises:

EOFError – Not enough bytes could be read.

Return type:

int

read_ulong()#

Read an unsigned 32-bit integer.

Raises:

EOFError – Not enough bytes could be read.

Return type:

int

read_until(sep)#

Read until the sep character is found and return all bytes before sep.

Raises:

EOFError – Not enough bytes could be read.

Parameters:

sep (int)

Return type:

bytes

read_ushort()#

Read an unsigned 16-bit integer.

Raises:

EOFError – Not enough bytes could be read.

Return type:

int

read_varchar1()#

Read a byte length and then return exactly length bytes.

Raises:

EOFError – Not enough bytes could be read.

Return type:

bytes

read_varchar2()#

Read a 2-byte length and then return exactly length bytes.

Raises:

EOFError – Not enough bytes could be read.

Return type:

bytes

read_varchar4()#

Read a 4-byte length and then return exactly length bytes.

Raises:

EOFError – Not enough bytes could be read.

Return type:

bytes

read_varchar8()#

Read an 8-byte length and then return exactly length bytes.

Raises:

EOFError – Not enough bytes could be read.

Return type:

bytes

little_a2s.filter_type(t, it, /)#

Filter through an iterable for elements of the given type.

Added in version 0.2.0.

Parameters:
Return type:

Iterator[TypeVar(T)]

little_a2s.first(t, it, /)#

Return the first element of the given type in an iterable.

Added in version 0.2.0.

Parameters:
Return type:

TypeVar(T) | None

little_a2s.last(t, it, /)#

Return the last element of the given type in an iterable.

Added in version 0.2.0.

Parameters:
Return type:

TypeVar(T) | None

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