Feat: Closing an existing port forward

[jaywonchung]

I implemented port forwarding cancellation for the process mux session implementation.

CC. @NobodyXu

Closes #110

[jonhoo]

This change is 

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

Attention: Patch coverage is 84.74576% with 9 lines in your changes missing coverage. Please review.

Project coverage is 81.56%. Comparing base (bacc76d) to head (03fb7bd).
Report is 15 commits behind head on master.

Files with missing lines	Patch %	Lines
src/process_impl/session.rs	68.96%	9 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

Files with missing lines	Coverage Δ
src/native_mux_impl/session.rs	95.60% <100.00%> (+1.00%)	⬆️
src/session.rs	81.10% <100.00%> (+3.90%)	⬆️
src/process_impl/session.rs	84.54% <68.96%> (-2.47%)	⬇️

... and 12 files with indirect coverage changes

[NobodyXu]

Sorry I was approving the workflow for your PR, but accidentally hit the "ready for review" button

[jaywonchung]

No worries. But actually good timing you're here -- I'm stuck with testing remote forwarding closure.

Calling read() on the socket will actually return a single Line Feed (ascii 10) character. Doing UnixStream::connect will actually connect to the socket without any problem, perhaps because there is one more character left to read. I suspected that the echo that is used to generate test data from the remote side is appending an extra newline so tried removing the final \n from the payload, and now read() hangs -- probably because there is not more data left to read and the socket blocks. The code path for local and remote forwarding are exactly the same and I actually verified local forwarding & cancellation working very well in my actual use case. Any ideas?

[jaywonchung]

Alright, on my local setup where I do remote forwarding and manually cancel, I found a way. There's one CI failing (With dependencies at minimal versions) but I presume that's because this new API is not part of the latest release of openssh.

[NobodyXu]

Sorry I was on another project and didn't check my github

You need to update Cargo.toml, to use latest openssh-mux-client, otherwise that CI would pick the lowest version fitting allowed by version requirements.

[jaywonchung]

Cool, now With dependencies at minimal versions passes as well!

[NobodyXu]

Thank you!