return Failure response when agent does not support extension

[71rd]

fix for #108

[wiktor-k]

Hi,

Thanks for the contribution 🙏 we definitely want this merged! I just need a moment to check if we don't need to support this for other commands too and think a bit about tests.

Hopefully that's not a problem. I'll be back 👋

[71rd]

thanks for the response.
I'm not in a hurry, i just wanted to remove a few unnecessary warnings in ssh-agent-mux 😃
i suspect it makes sense to also add it to the blocking module so i also handled the case there.
if you find something else that should be added or changed about this PR i'm happy to help

[jcspencer]

This looks correct to me; the agent protocol has been recently codified as RFC9987, and section 5.6 defines this as the expected response when an extension either doesn’t exist, or the agent doesn’t support extensions at all.

One thing that I am noticing though is that we don’t seem to cover SSH_AGENT_EXTENSION_FAILURE (or, for us, ExtensionFailure) here either… I think this would be good to add as separate branch here too, likely with it’s own distinct AgentError variant for consumers to process.

[71rd]

thanks @jcspencer, seems like a good suggestion.

i added the case for client.rs and blocking.rs

[71rd]

please ignore the earlier push mix 🙈
it should be fixed now

[wiktor-k]

Phew, merged! Sorry for the delay and thank you very much for your contribution! 🙇

It may take a moment to get into a new release since I've got another idea for something else but we'll get there... eventually 😅

Have a nice day! 👋

[71rd]

All good :D
Thank you for maintaining the library
Wish you also have a nice day