Add ftptls

[bartvaneswhiffle]

See #1580.

It is basically a copy of the FTP class in fsspec, with a modification to use FTP_TLS and one addtional change.

Please have a look at this.

[bartvaneswhiffle]

I've added tests (mostly copied from test_ftp.py, not all are yet working. Could use some help here :)

[martindurant]

Thanks for contributing!

Before going further, do you think it's possible to provide the extra features as options on the original FTP filesystem rather than create a new variant that is largely the same?

[bartvaneswhiffle]

No worries, in a sense we could give two additional arguments on the init of FTPFileSystem:

• ssl=False
• prot_p=False

Then we could modify the _connect to use either FTP or TLS_FTP and modify the init to activate prot_p if it's equal to True after setting the connection.

How does this sound to you?

[martindurant]

Yes, exactly.

For testing, you would need a secured server, of course, but you could essentially run all FTP tests with standard and secure servers.

[bartvaneswhiffle]

I've removed the the ftp_tls class and integrated it with the ftp class. Two tests are currently still failing: the test with caching (test_complex) and the test with transaction (test_transaction), not sure how to fix those?

[martindurant]

Ping: is this PR still progressing?

[bartvaneswhiffle]

Thanks for the reminder, so far I've not had the time to further implement the tests.

[bartvaneswhiffle]

I've found some time to update the tests. The pyftpdlib server has been replaced with script that starts a pyftpdlib server that accepts TLS. Furtermore, docstrings and codestyle improvements have been made.

@martindurant: Do you understand why the CI / downstream fails?

[martindurant]

Do you understand why the CI / downstream fails

Please merge from master and try again

[bartvaneswhiffle]

Do you understand why the CI / downstream fails

Please merge from master and try again

All checks have passed :)