mqtt 解析包代码

MQTT（Message Queuing Telemetry Transport）是一种轻量级的通讯协议，常用于物联网设备之间的通信。下面是一个简单的MQTT解析包的代码示例。

import struct

def parse_mqtt_packet(packet):
    # 解析固定报头的第一个字节，获取报文类型和标志位
    packet_type = packet[0] >> 4
    flags = packet[0] & 0x0F
    print("Packet Type:", packet_type)
    print("Flags:", flags)

    # 解析剩余长度字段
    remaining_length = 0
    multiplier = 1
    index = 1
    while True:
        digit = packet[index]
        remaining_length += (digit & 127) * multiplier
        multiplier *= 128
        index += 1
        if (digit & 128) == 0:
            break
    print("Remaining Length:", remaining_length)

    # 解析可变报头和负载数据
    if packet_type == 1:
        # 连接请求报文
        protocol_name_length = struct.unpack("!H", packet[index:index+2])[0]
        index += 2
        protocol_name = packet[index:index+protocol_name_length].decode("utf-8")
        index += protocol_name_length
        print("Protocol Name:", protocol_name)

        protocol_version = packet[index]
        index += 1
        print("Protocol Version:", protocol_version)

        flags = packet[index]
        index += 1
        print("Flags:", flags)

        keep_alive = struct.unpack("!H", packet[index:index+2])[0]
        index += 2
        print("Keep Alive:", keep_alive)

        client_id_length = struct.unpack("!H", packet[index:index+2])[0]
        index += 2
        client_id = packet[index:index+client_id_length].decode("utf-8")
        index += client_id_length
        print("Client ID:", client_id)

    elif packet_type == 3:
        # 发布报文
        topic_length = struct.unpack("!H", packet[index:index+2])[0]
        index += 2
        topic = packet[index:index+topic_length].decode("utf-8")
        index += topic_length
        print("Topic:", topic)

        message = packet[index:]
        print("Message:", message)

    # 解析完整个报文后，可以根据需要进行其他操作，如校验报文合法性、执行相应的逻辑等。

# 测试示例
packet = b"\x10\xCC\x00\x04\x4D\x51\x54\x54\x04\x02\x00\x0A\x4D\x79\x43\x6C\x69\x65\x6E\x74\x49\x44"
parse_mqtt_packet(packet)

以上代码是一个简单的MQTT解析包示例，用于解析MQTT连接请求和发布报文。函数`parse_mqtt_packet`接收一个字节数组作为参数，通过解析字节数组中的字段，可以获取报文类型、标志位、剩余长度、可变报头和负载数据等信息。可以根据业务需要，进一步扩展代码以支持其他MQTT报文类型的解析。