MKDIR result message interpretation

[o0verhaul]

I ran across an FTP server that responds in a way that FileZilla doesn't expect when MKDIR finds a directory that already exists. The response is:

517 <path>: File exists.

[Alexander Schuch]

Which version of FileZilla did you use? Can you provide a log file?

[o0verhaul]

I used 3.0.9.2 when I discovered this difficulty.

Don't know about a log file, but here's the chatter between FileZilla and the server:
Status: Creating directory '/bin/'...
Command: CWD /
Response: 250 CWD command successful.
Command: MKD bin
Response: 517 bin: File exists.

[o0verhaul]

Also crawling around through the source of the Kerberos GSSFTP daemon, it seems to return 550 instead of 517, but otherwise use the system-dependent error code lookup as its reason. Apparently Linux's and AIX's error string for mkdir is "File exists."

[Alexander Schuch]

I am using Pure-FTPd and the log says the following:

Status: Creating directory '/web/template/'...
Command: MKD template
Response: 550 Can't create directory: File exists
Command: MKD /web/template/
Response: 550 Can't create directory: File exists

Not sure what to do with the 517 answer, as I do not know the FTP specification.

[Tim Kosse]

The FTP specifications don't give any semantics to the error codes for MKD. Especially not to the human-readable string past the actual error code.
I've added some heuristics to guess what the server means but it can't possibly catch all replies imaginable.