Allow channel handler to control adjust_window message sending

[yarisx]

The channel handler callback module can implement the get_adjust/0 function returning either 'immediate' or 'delayed' values. In the latter case the channel handler module is responsible for invoking ssh_connection:adjust_window/3 to send ssh_msg_adjust_window to the peer.

[github-actions[bot]]

CT Test Results

    2 files     29 suites   20m 55s ⏱️   467 tests   463 ✅  4 💤 0 ❌ 1 672 runs  1 648 ✅ 24 💤 0 ❌

Results for commit fb2d5d93.

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[u3s]

you can ignore "unexpected event found" errors in ssh test results at this stage, they're probably unrelated.

[yarisx]

Rebased to the latest master, hope that makes test failures go away.

[u3s]

sorry for delay.

please convert draft into PR.

I think this is a wanted feature but we need to discuss some details:

• naming: maybe auto and manual return values + window_handling_mode instead of get_adjust ?
• I would like it be more self documenting ... maybe you have a better idea?

[yarisx]

I've changed the implementation because the initial code did not cover the case when clients do not utilize ssh_client_channel behaviour. Now any channel handler can set window handling mode using the new exported ssh_connection_handler:set_window_handling_mode/3. Also created a couple of tests to check that the code works, hopefully - as intended.

[u3s]

• this PR is affected by PR-9309
• this PR still looks interesting but maybe we could re-discuss how it should look like - as functionality triggering it (PR-8345) is reverted.
• I'm leaning towards having this logic nested in ssh_client_channel behavior, and leaving ssh_connection simple - I think this was initial intention behind modules in ssh application
• what do you think about it?

[yarisx]

On one hand I agree that it would be better to keep the code clean and simple. On the other hand if this functionality is limited to the ssh_client_channel behaviour then any client that does not implement the behaviour cannot enjoy this kind of flow control. Also if I read the code correctly modules like ssh_cli, ssh_shell, ssh_sftpd also can't have this functionality without patching each module, because they implement ssh_server_channel behaviour which does not have any common code for handling ssh messages (which ssh_client_channel has). But then again if there was no demand for the feature up until now, nobody will get hurt by any implementation.

[yarisx]

I've pushed the changes to restore window-adjusting functionality to ssh_client_channel, is anything more expected from me?

[yarisx]

@IngelaAndin @u3s I see that the PR has the "stalled" label, probably have missed something. Could you please comment on what is expected from my side?

[IngelaAndin]

@yarisx No waiting label means that you need to do something, stalled label means that we are swamped with other work and have problems prioritizing this at the moment , but please be patient because we are interested.