前言

由于阿里云物联网套件关于设备认证的文档不够详细，笔者差不多摸索了几天才连接上MQTT。下面是使用Python模拟设备接入阿里云的MQTT。

概述

阿里云物联网套件提供两种接入方式：

1. MQTT客户端域名直连（资源受限设备推荐）
2. 先HTTPS发送授权后再连接MQTT（一些特殊增值服务，比如设备级别的引流）

本文主要介绍第一种接入方式，TCP直连，并提供Python代码示例。

主要参数

连接域名

<ProductKey>.iot-as-mqtt.cn-shanghai.aliyuncs.com:1883

MQTT Connect报文参数

1、mqttClientId

mqttClientId = "<ClientId>"+"|securemode=3,signmethod=hmacsha1,timestamp=132323232|"

2、mqttUsername

使用&拼接<DeviceName>和<ProductKey>。

mqttUsername = "<DeviceName>&<ProductKey>"

3、mqttPassword

把以下参数按字典键名排序，再把键名都拼接起来（没有分隔符）生成content，然后以DeviceSecret为盐，对content进行hma_sha1加密，最后二进制转为十六进制字符串表示。

• clientId
• deviceName
• productKey
• timestamp

mqttPassword = hmac_sha1(DeviceSecret, content).toHexString();

示例

假设

• clientId = 12345
• deviceName = device
• productKey = pk
• timestamp = 789
• signmethod = hmacsha1

content拼接结果：clientId12345deviceNamedeviceproductKeypktimestamp789

注意：不用拼接signmethod参数。

对content以DeviceSecret为盐进行hmacsha1加签后，再转为十六进制字符串，最后结果：FAFD82A3D602B37FB0FA8B7892F24A477F851A14

注意：不需要base64。

最后总结一下生成的参数：

• mqttHost = pk.iot-as-mqtt.cn-shanghai.aliyuncs.com
• mqttPort = 1883
• mqttClientId = 12345|securemode=3,signmethod=hmacsha1,timestamp=789|
• mqttUsername = device&pk
• mqttPassword = FAFD82A3D602B37FB0FA8B7892F24A477F851A14

参数说明

示例代码

填写自己的ProductKey、ClientId、DeviceName、DeviceSecret。

# coding=utf-8
# !/usr/bin/python3

import datetime
import time
import hmac
import hashlib
import math

TEST = 0

ProductKey = ""
ClientId = "12345"  # 自定义clientId
DeviceName = ""
DeviceSecret = ""

# signmethod
signmethod = "hmacsha1"
# signmethod = "hmacmd5"

# 当前时间毫秒值
us = math.modf(time.time())[0]
ms = int(round(us * 1000))
timestamp = str(ms)

data = "".join(("clientId", ClientId, "deviceName", DeviceName,
                "productKey", ProductKey, "timestamp", timestamp
                ))
# print(round((time.time() * 1000)))
print("data:", data)

if "hmacsha1" == signmethod:
    ret = hmac.new(bytes(DeviceSecret, encoding="utf-8"),
                   bytes(data, encoding="utf-8"),
                   hashlib.sha1).hexdigest()
elif "hmacmd5" == signmethod:
    ret = hmac.new(bytes(DeviceSecret, encoding="utf-8"),
                   bytes(data, encoding="utf-8"),
                   hashlib.md5).hexdigest()
else:
    raise ValueError

sign = ret
print("sign:", sign)

# ======================================================

strBroker = ProductKey + ".iot-as-mqtt.cn-shanghai.aliyuncs.com"
port = 1883

client_id = "".join((ClientId,
                     "|securemode=3",
                     ",signmethod=", signmethod,
                     ",timestamp=", timestamp,
                     "|"))
username = "".join((DeviceName, "&", ProductKey))
password = sign

print("="*30)
print("client_id:", client_id)
print("username:", username)
print("password:", password)
print("="*30)

def secret_test():
    DeviceSecret = "secret"
    data = "clientId12345deviceNamedeviceproductKeypktimestamp789"
    ret = hmac.new(bytes(DeviceSecret, encoding="utf-8"),
                   bytes(data, encoding="utf-8"),
                   hashlib.sha1).hexdigest()
    print("test:", ret)


# ======================================================
# MQTT Initialize.--------------------------------------

try:
    import paho.mqtt.client as mqtt
except ImportError:
    print("MQTT client not find. Please install as follow:")
    print("git clone http://git.eclipse.org/gitroot/paho/org.eclipse.paho.mqtt.python.git")
    print("cd org.eclipse.paho.mqtt.python")
    print("sudo python setup.py install")


# ======================================================
def on_connect(mqttc, obj, rc):
    print("OnConnetc, rc: " + str(rc))

    mqttc.subscribe("test", 0)


def on_publish(mqttc, obj, mid):
    print("OnPublish, mid: " + str(mid))


def on_subscribe(mqttc, obj, mid, granted_qos):
    print("Subscribed: " + str(mid) + " " + str(granted_qos))


def on_log(mqttc, obj, level, string):
    print("Log:" + string)


def on_message(mqttc, obj, msg):
    curtime = datetime.datetime.now()
    strcurtime = curtime.strftime("%Y-%m-%d %H:%M:%S")
    print(strcurtime + ": " + msg.topic + " " + str(msg.qos) + " " + str(msg.payload))
    on_exec(str(msg.payload))


def on_exec(strcmd):
    print("Exec:", strcmd)
    strExec = strcmd


# =====================================================
if __name__ == '__main__':
    if TEST:
        secret_test()
        exit(0)

    mqttc = mqtt.Client(client_id)
    mqttc.username_pw_set(username, password)
    mqttc.on_message = on_message
    mqttc.on_connect = on_connect
    mqttc.on_publish = on_publish
    mqttc.on_subscribe = on_subscribe
    mqttc.on_log = on_log

    mqttc.connect(strBroker, port, 120)
    mqttc.loop_forever()

终于知道之前为什么总是连接不上了！！！之前文档对password加密的字段是多了「signmethodhmacsha1」字符串！