micropython
umqtt.simple using ssl: check_msg() throws NotImplementedError
The check_msg() function uses socket.setblocking() to check for pending messages without blocking. While working fine with normal sockets this leads to an NotImplementedError when used with a ssl connection.
To create a ssl connection the ussl.wrap_socket() function is used which returns a ussl._SSLSocket object. For the _SSLSocket class there exists only a method stub for setblocking() that throws a NotImplementedError. So basically the _SSLSocket.setblocking() method needs to be implemented in the ussl library for this to work.
So basically the _SSLSocket.setblocking() method needs to be implemented in the ussl library for this to work.
No, of course no. You're staying in you car ahead of big-big pit on the street with a warning sign in front of it. And now you're saying that to pass the street you need to remove this warning sign.
Ok, I might have missed something here but can't see what. What is the sign warning me from?
That non-blocking I/O support for SSL sockets is not implemented, and it's pretty complex thing ("big-big pit"), or otherwise it would have been implemented long ago.
I see...so this is a more complex topic... But is there a workaround? I need to send regular ping requests to the mosquitto server in order to keep the connection alive. I can't do that with a blocking socket. At the moment all I can do is drop the ssl encryption and use a normal socket.
MrLeeh could you fork a new thread and send pings? I'm very new at this so apologies if that sounds like an ignorant question, but it seems to me that would work.
@SlowBro904 with full-grown Python this would be possible I guess. But afaik there is no threading implemented in Micropython, yet.
Threading is usable in Pycom's uPy, and I have successfully flashed that to a standard WROOM-32. Theirs is open source.
(It's not completely usable in that state, one must also alter the pins in a csv file and recompile, but I wanted to see it done as a proof of concept. Also their threading is not complete, with no way to exit a thread from the outside. I hacked a workaround using a global variable as a flag and it works.)
Oh, and I found this. You /might/ have threading in your implementation after all. Go try it. https://forum.micropython.org/viewtopic.php?t=1864
As a workaround, check_msg might be modified to use polling:
def check_msg(self, timeout):
poller = uselect.poll()
poller.register(self.sock, uselect.POLLIN)
res = poller.poll(timeout) # time in milliseconds
if not res:
return None
return self.wait_msg()
mqtt.simple should work with SSL for many years now. If there are issues, please re-open with details on how to reproduce.
