add a test case for QUIT command with a transfer in progress

[drakkan]

specs are not completly clear

If file transfer is in progress, the connection will remain open for result response and the server will then close it.

it is not specified whether we have to send the QUIT response and then the transfer close response or vice versa.

Some results from other FTP servers.

ProFTPD:

EPSV
229 Entering Extended Passive Mode (|||8257|)
RETR sub.mkv
150 Opening BINARY mode data connection for sub.mkv (13313790 bytes)
QUIT
226 Trasferimento completato
221 Arrivederci.

Pure-FTPD (abort the transfer):

EPSV
229 Extended Passive mode OK (|||64013|)
RETR sub.mkv
150-Accepted data connection
150 13001.7 kbytes to download
QUIT
426 ABORT
226-Transfer aborted
226 0.000 seconds (measured here), 332.67 Mbytes per second

vsftpd

EPSV
229 Entering Extended Passive Mode (|||46192|)
RETR sub.mkv
150 Opening BINARY mode data connection for sub.mkv (13313790 bytes).
QUIT
226 Transfer complete.
221 Goodbye.

I haven't tested pyftpdlib but according to the code here. It sends the QUIT response before the transfer close.

We behave like ProFTPD and vsftpd. The test case ensures that the behavior is not changed by mistake

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Codecov Report

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[drakkan]

I confirm that pyftpdlib send transfer close response after quit

EPSV
229 Entering extended passive mode (|||48977|).
RETR sub.mkv
125 Data connection already open. Transfer starting.
QUIT
221 Goodbye.
226 Transfer complete.

tested using this sample python program

from pyftpdlib.authorizers import DummyAuthorizer
from pyftpdlib.handlers import FTPHandler
from pyftpdlib.servers import FTPServer

authorizer = DummyAuthorizer()
authorizer.add_user("nicola", "password", "/home/nicola", perm="elradfmwMT")

handler = FTPHandler
handler.authorizer = authorizer

server = FTPServer(("127.0.0.1", 2121), handler)
server.serve_forever()

[fclairamb]

LGTM !