Problem with SimpleConnectivityChecker reliance on phpseclib's SSH2::isConnected functionality

[kevinreniers]

Bug Report

Q	A
Flysystem Version	3.15.1
Adapter Name	flysystem-sftp-v3
Adapter version	3.15.0

Summary

I've already described the issue in detail on the phpseclib/phpseclib issue tracker as well: phpseclib/phpseclib#1923. This issue also links to a consistent reproducer project.

In SimpleConnectivityChecker, the flysystem-sftp-v3 adapter relies on phpseclib3\Net\SFTP::isConnected to check that the underlying connection is still connected. If not, it will try to create a new one. However, for long-running processes where the underlying TCP/IP connection may have timed out after a while, this check fails because the exposed phpseclib3\Net\SFTP::isConnected functionality cannot/does not capture this case.

I'm also reporting this issue here because I believe your library should not rely (only?) on SFTP::isConnected. The maintainer of phpseclib gave a suggestion on their tracker on how to check the underlying socket as well, if that helps/ feels appropriate.

How to reproduce

I have a reproducer project that highlights the issue.

https://github.com/kevinreniers/phpseclib-iss1923