Send data to Azure IoTHub with MQTT protocol, without using pybytes (solved)

[railmonitor]

I was looking around for some examples and found this:
Re: AMQP to Azure IoTHub via CAT-M

I have used the libraries downloaded from github: https://github.com/micropython/micropython-lib

And tried both versions of the generate_sas_token() method without luck. It seems that either the API, libraries or something has changed since. Does anyone got a working example running?

Current firmware:

Thanks in advance!

Edit: So i got a little further now, was using the connection string arguments wrong. Now i can get it to compile all the way until client.connect(), where i run in to trouble with the libraries. I am using the umqtt.simple library from micropython-lib-master, which is supposed to be for use with micropython. I tried the regular mqtt library from pycom as well, but ran into the same problem:

This refers to following line in the library:

self.sock.write(s)

I did some futher digging based on the TypeError message, and found some posts:

https://forum.pycom.io/topic/3222/object-with-buffer-protocol-required/5
https://forum.micropython.org/viewtopic.php?t=2797

Seems that there was some changes to Micropython, and that the library isn't updated. From the above posts, i see that the "TypeError: object with buffer protocol required", can be fixed by putting brackets or packing what you write in a bytearray. I tried both, but ran into similar errors other places in the library. I don't want to edit too much in libraries, so i would really appreciate any help on this topic!

[Mirox]

Are you also using client.check_msg() to check if messages has been sent to the device? When I use this function and no message is the queue its blocking my code until I send a message to the device but I would like to only check if there is a message and then the code should be continued. Do you have any suggestions for this problem?

[railmonitor]

Following my Edit, i got another step further. I am going to show my main code below here, to better show and tell what i found out so far (Sorry for all the outcommenting, been at it for a while now).

What i did now, was to edit the client = MQTTClient() parameters for user and password, with a b'username' and b'password', which seems to have helped others (see link):

https://forum.pycom.io/topic/4775/solved-mqtt-and-tls/5

This got rid of the "object with buffer protocol required" error. Now i am instead getting a MQTTException: 3

I am no sure what is causing the problems. Would really appreciate some updated documentation / examples on how to do this!

Code below:

from wlan_module import wlan_module
from simple import MQTTClient
#import paho.mqtt.client as mqtt
from base64 import b64encode, b64decode
from _sha256 import sha256
from hmac import HMAC
from parse import quote_plus, urlencode, quote
import machine
import time

wl = wlan_module()
wl.wifiConnect()

#set time
print("setting time")
rtc = machine.RTC()
rtc.ntp_sync("pool.ntp.org")
while not rtc.synced():
    machine.idle()
print("Time set to: " + str(rtc.now()))

def generate_sas_token(uri, key, keyName, ttl=3600):
    expiry = int(time() + ttl)

    uri = quote_plus(uri)
    sas = key.encode('utf-8')
    string_to_sign = (uri + '\n' + str(expiry)).encode('utf-8')
    signed_hmac_sha256 = HMAC(sas, string_to_sign, sha256)
    signature = quote(b64encode(signed_hmac_sha256.digest()))
    return {
        'expiry': expiry,
        'token': 'SharedAccessSignature sr={}&sig={}&se={}&skn={}'.format(uri, signature, expiry, keyName)
        #'token': 'SharedAccessSignature sr={}&sig={}&se={}'.format(uri, signature, expiry)
    }
#Azure IoT-hub settings
hostname = "XXXXXXXXXXXXXX"

#This needs to be the key of the "device" IoT-hub shared access policy, NOT the device
policy_name = "XXXXXXXXXXXXX"
primary_key = "XXXXXXXXXXXXXXXXXXXXX"

device_id = "XXXXXXXXXXXX"

uri = "{hostname}/devices/{device_id}".format(hostname=hostname, device_id=device_id)

print(generate_sas_token(uri, primary_key, policy_name))
print(uri)

password =generate_sas_token(uri, primary_key, policy_name)

#print(password)

username_fmt = "{}/{}/api-version=2018-06-30"
username = username_fmt.format(hostname, device_id)

client = MQTTClient(device_id, hostname, user=b'username', password=b'password', ssl=True)

client.connect()

topic = "devices/{device_id}/messages/events/".format(device_id=device_id)
client.publish(topic, "test", qos=1)

Update: I made it work finally, leaving my solution here, for anyone in similar situation. Basically it was a combination of a missing certificate, and an error in the "generate_sas_token()" method i was using. So the solution was to use the Boston Certificate mentioned here: http://blogs.recneps.org/post/Connecting-the-ESP-8266-to-Azure-IoT-Hub-using-MQTT-and-MicroPython

And the generate_sas_token() method from here: https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-devguide-security

from base64 import b64encode, b64decode
from hashlib import sha256
from time import time
from urllib import parse
from hmac import HMAC

def generate_sas_token(uri, key, policy_name, expiry=3600):
    ttl = time() + expiry
    sign_key = "%s\n%d" % ((parse.quote_plus(uri)), int(ttl))
    print sign_key
    signature = b64encode(HMAC(b64decode(key), sign_key.encode('utf-8'), sha256).digest())

    rawtoken = {
        'sr' :  uri,
        'sig': signature,
        'se' : str(int(ttl))
    }

    if policy_name is not None:
        rawtoken['skn'] = policy_name

    return 'SharedAccessSignature ' + parse.urlencode(rawtoken)