PASV implementation is incompatible with ncftp: Cannot parse PASV response: listen socket created

[eLvErDe]

Hello,

It seems aioftp server cannot communicate with NCFTP, here is the client transcript:

NcFTP 3.2.5 (Feb 02, 2011) by Mike Gleason (http://www.NcFTP.com/contact/).
Connecting to 10.1.1.1...                                                                                                                                                                                       
welcome
Logging in...                                                                                                                                                                                                      
normal login
'help' not implemented                                                                                                                                                                                             
Logged in to 10.1.1.1.                                                                                                                                                                                          
ncftp / > ls
Cannot parse PASV response: listen socket created

It stays stuck here, on server side I can read the following logs:

2021-10-08 21:03:51,221 DEBUG    [aioftp.server] 150 list transfer started
2021-10-08 21:03:52,222 DEBUG    [aioftp.server] 425 Can't open data connection

I dig into the issue and came up with a workaround, the issue is here:
https://github.com/aio-libs/aioftp/blob/master/aioftp/server.py#L1437

Replacing

code, info = "227", ["listen socket created"]

With

code, info = "227", []

Make ncftp client work perfectly fine.

Sadly I do not see any easy way to fix this without inheriting and copy/pasting the whole pasv method, which is kinda bad.

What do you think about this incompatibility ?

Regards, Adam.

[pohmelie]

It looks like ncftp do not respect ftp (rfc959)[https://datatracker.ietf.org/doc/html/rfc959] part 4.2. Multiline responses allowed.

[eLvErDe]

Not really surprised but would you consider a "compat" option for that ?

[eLvErDe]

Meanwhile, I inherited from Server and copy/pasted pasv method but that's far from optimal

[pohmelie]

Feel free to make a PR for this feature.