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Telnet "_handle_control_chars_response" gets stuck in the infinite loop

See original GitHub issue

Some of my switches sends in telnet: IAC WILL ECHO IAC WILL SUPPRESS-GO-AHEAD before login prompt. If they do not receive: IAC DO ECHO IAC DO SUPPRESS-GO-AHEAD they will repeat control characters infinitely, so “_handle_control_chars_response” gets stuck in the infinite loop. https://github.com/carlmontanari/scrapli/blob/81d7700746fa41773b93601b9c909de5e3d9c2f2/scrapli/transport/plugins/asynctelnet/transport.py#L86-L91

I’ve changed that code to:

            if cmd in (DO, DONT):
                # if server says do/dont we always say wont for that option
                self.stdin.write(IAC + WONT + c)
            elif cmd in WILL:
                # if server says will we always say do for that option
                self.stdin.write(IAC + DO + c)
            elif cmd in WONT:
                # if server says wont we always say dont for that option
                self.stdin.write(IAC + DONT + c)

And it works. No more loops.

Issue Analytics

State:
Created 2 years ago
Reactions:1
Comments:13 (7 by maintainers)

Top GitHub Comments

1reaction

carlmontanaricommented, Jul 27, 2021

Awesome, just pushed to develop. Thanks again! Hopefully this is the last of the asynctelnet gremlins! 😁

1reaction

carlmontanaricommented, Jul 27, 2021

Ok, tested your fix and looks like everything is working as expected on all the test platforms I have!

Let me know if you wanna PR or want me to just slap it in there, up to you!

Thanks for the help with this!

Carl

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