CPython example not working with secure broker

[brentru]

This library currently works with CPython sockets connecting to a insecure MQTT broker port (1883) but falls down when attempting to connect to a secure MQTT broker port (8883):

  File "/Users/brentrubell/Desktop/github_brentru/Adafruit_CircuitPython_MiniMQTT/test_cpython.py", line 63, in <module>
    mqtt_client.connect()
  File "/Users/brentrubell/Desktop/github_brentru/Adafruit_CircuitPython_MiniMQTT/adafruit_minimqtt/adafruit_minimqtt.py", line 467, in connect
    self._sock = self._get_socket(self.broker, self.port)
  File "/Users/brentrubell/Desktop/github_brentru/Adafruit_CircuitPython_MiniMQTT/adafruit_minimqtt/adafruit_minimqtt.py", line 284, in _get_socket
    sock = self._ssl_context.wrap_socket(sock, server_hostname=host)
  File "/Users/brentrubell/Desktop/github_brentru/Adafruit_CircuitPython_MiniMQTT/adafruit_minimqtt/adafruit_minimqtt.py", line 114, in wrap_socket
    return _FakeSSLSocket(socket, self._iface.TLS_MODE)
AttributeError: 'NoneType' object has no attribute 'TLS_MODE'```

[brentru]

Digging deeper, this is more an issue with the example itself and the macOS SSL installation under Python3 than the library, I'll be making a pull request shortly to fix it.

In the future, if a user on macOS gets [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: self signed certificate in certificate chain (_ssl.c:1123), they'll need to upgrade the certifi package by running the following command:

/Applications/Python\ 3.9/Install\ Certificates.command

[tannewt]

Why are you using FakeSSLSocket when using CPython? Your self._ssl_context should be from the real ssl library.

[tannewt]

FakeSSLSocket should only be used with ESP32SPI.

[brentru]

@tannewt The code which threw this error incorrectly did not pass the ssl_context from the ssl library into the MiniMQTT constructor and looked like:

# Set up a MiniMQTT Client
mqtt_client = MQTT.MQTT(
    broker=secrets["broker"],
    username=secrets["aio_username"],
    password=secrets["aio_key"],
    socket_pool=socket,
)

Instead of:

# Set up a MiniMQTT Client
mqtt_client = MQTT.MQTT(
    broker=secrets["broker"],
    username=secrets["aio_username"],
    password=secrets["aio_key"],
    socket_pool=socket,
    ssl_context=ssl.create_default_context(),
)

[brentru]

Looking at how requests does it, the code should raise a RuntimeError that the "ssl_context must be set before using adafruit_mqtt for secure MQTT.", but it appears that the SSLContext is incorrectly set to _FakeSSLContext(_the_interface) if not set in the __init__ for this library.