>> as you can see, the FTP server proposes to two parallel connections to
>> get their data from the SAME port ! in this situation I'm pretty sure
>> that the connection will get bound randomly, hence the swap in some
>> situations!
>>
>> so so, what to do? when using passive mode, should we find a way to
>> enforce connection of data socket before letting a new EPSV/PASV?
>
> Sounds like a very "clever" server implementation! ;-) Yes, I guess you'll
> need to delay your subsequent transfers until the connect has been
> performed and I guess you only know that for sure with libcurl when it has
> started to transfer data (or failed).
i am going to try that.
ok, it works, but it degrades performances dramitically :( (to the point
that multiple connections gives almost no advantage).

I wonder if we could have another approach. We could detect the PASV
collision and repeat the PASV commands (it seems that IIS accepts that), it
would cause the slow-down only in case of actual collision.
I well understand that this is "IIS bug handling" but IIS is really spread
and having libcurl just inverting silently the data when you try to download
two files in parallel from an IIS server is not cool.

Armel
Received on 2006-08-24