paho.mqtt.proxy_set() - support

[Sohaib90]

This commit adds the functionality of paho-mqtt's proxy_set() to asyncio-mqtt

[frederikaalund]

Thanks for opening this PR. 👍 Looks good to me. I only have one minor comment about typing (see the review).

[frederikaalund]

You forgot the Optional part here. :)

[Sohaib90]

If you look at the description here: https://github.com/eclipse/paho.mqtt.python/blob/225ab3757f6818ba85eb80564948d1c787190cba/src/paho/mqtt/client.py#L875

It says

(Required)
proxy_type: One of {socks.HTTP, socks.SOCKS4, or socks.SOCKS5}
proxy_addr: IP address or DNS name of proxy server
(Optional)
proxy_rdns: boolean indicating whether proxy lookup should be performed
    remotely (True, default) or locally (False)
proxy_username: username for SOCKS5 proxy, or userid for SOCKS4 proxy
proxy_password: password for SOCKS5 proxy

In line with that shouldnt it be like this, or should I change it to Optional?

[Sohaib90]

Also do you think it is a good idea to add some documentation so that the users know that the functionality exists (e.g a small example) in the README.md in another PR?

[frederikaalund]

Ah, good point. 👍 If those arguments are required then let's not use default valures (= None) for them.
Looking at the paho implementation, we could have a signature like this:

def __init__(
    self,
    *, 
    proxy_type: int,
    proxy_addr: str,
    proxy_rdns: Optional[bool] = True,
    proxy_username: Optional[str] = None,
    proxy_password: Optional[str] = None
): ...

This way, the user must supply the proxy_type and proxy_addr arguments.

Also do you think it is a good idea to add some documentation so that the users know that the functionality exists (e.g a small example) in the README.md in another PR?

Yes, that's a good idea. 👍
Specifically, we should let people know that this whole proxy is an "extra" feature (even in paho) that requires the PySocks dependency.

[Sohaib90]

I have fixed it and committed it as well.
Alright. I will work on the documentation and create a PR for that

[frederikaalund]

LGTM and merged. 👍 Thank you for your contribution to asyncio-mqtt (again). :)

[Sohaib90]

Thank you for the opportunity (again) :D