Module mqtt 

MQTT (Message Queuing Telemetry Transport) layer implementation.

Implements MQTT v3.1, v3.1.1, and v5.0 packet parsing as a zero-copy view into a packet buffer.

Fixed Header Format

Byte 0:  [msg_type(4 bits)] [dup(1)] [qos(2)] [retain(1)]
Byte 1+: Remaining Length (variable-length encoded, 1-4 bytes)

Message Types

Value	Name	Direction
1	CONNECT	Client -> Server
2	CONNACK	Server -> Client
3	PUBLISH	Both
4	PUBACK	Both
5	PUBREC	Both
6	PUBREL	Both
7	PUBCOMP	Both
8	SUBSCRIBE	Client -> Server
9	SUBACK	Server -> Client
10	UNSUBSCRIBE	Client -> Server
11	UNSUBACK	Server -> Client
12	PINGREQ	Client -> Server
13	PINGRESP	Server -> Client
14	DISCONNECT	Both (v5.0)
15	AUTH	Both (v5.0)

Re-exports

pub use builder::MqttBuilder;

Modules

builder

MQTT packet builder.

Structs

MqttLayer

MQTT layer – a zero-copy view into a packet buffer.

Constants

AUTH

CONNACK

CONNECT

DISCONNECT

MQTT_MIN_HEADER_LEN

Minimum MQTT header: 1 byte fixed header + at least 1 byte remaining length.

MQTT_PORT

Default MQTT TCP port.

PINGREQ

PINGRESP

PUBACK

PUBCOMP

PUBLISH

PUBREC

PUBREL

SUBACK

SUBSCRIBE

UNSUBACK

UNSUBSCRIBE

Statics

MQTT_FIELD_NAMES

Field names exported for Python/generic access.

Functions

decode_variable_length

Decode a variable-length integer from buf starting at offset.

encode_variable_length

Encode a value as an MQTT variable-length integer.

is_mqtt_payload

Check whether a TCP payload looks like an MQTT packet.

message_type_name

Return the string name for an MQTT message type value.