[tahoe-dev] tahoe now has an FTP server!

[Nathan]

This feature is the first instance (aside from the commercial
AllMyData service) I am aware of that maps a concept of "user account"
to Tahoe's cap design.

I have some questions:

Can I enable anonymous ftp access?

If I did, would the result differ much from the WUI interface in its
security model?


I'm especially interested in the latter.

Specifically for browsers:
Can browsers do anything other than ftp retrieval?  Can they list
directories?  If they retrieve html, do they render it?  If it
renders, is its domain the host, port pair of the server?


Do tahoe devs envision deploying this username/password access scheme
elsewhere?  (For instance, optionally in the WUI?)


Nathan


On Thu, Oct 9, 2008 at 11:15 AM, Brian Warner
<warner-tahoe at allmydata.com> wrote:
> Just an update: I was able to get the FTP server code working and
> pushed into Tahoe trunk (ticket #512), and it seems to work pretty well.
>
> The limitation is that it needs a patch to Twisted, otherwise the uploading
> 'PUT' command will finish before the file has actually been uploaded and
> linked. Without such a patch, most advanced FTP clients will probably be
> unhappy, since they tend to list the directory as soon as the PUT finishes,
> and if they don't see the file that they think they just uploaded, they'll be
> confused.
>
> On the other hand, it doesn't need a special version of Twisted.. the FTP
> server code has been around since Twisted-2.4.0 .
>
> There are two user-handling mechanisms available. The first is a simple
> flat-file, with lines of username/password/rootcap, which is quite suitable
> for local deployment. The second mechanism uses a web-service that is
> unsurprisingly similar to the allmydata.com authentication scheme, which
> submits a username/password pair to a database-checking script named
> "native_client.php", and gets back a rootcap.
>
> We're currently testing this against a number of FTP clients. Typical BSD
> ftp, ncftp, and a couple of Mac ftp clients seem ok so far. Windows will
> mount an FTP server as a regular virtual drive, and that appears to work
> pretty well. The Mac OS-X Finder will mount an FTP server as a virtual drive,
> but read-only, and only if there is no "@" in the username. Since
> allmydata.com sues email addresses as usernames, this is a bit of a drag.
> We're still investigating.
>
> Rob Kinninmont asked:
>
>> what does it take to get from there to sftp?
>
> Not as much work as one might think, and too much work to get done this week.
>
> Twisted's FTP code is split into two pieces. The lower-layer
> protocol-handling stuff is in twisted/protocols/ftp.py, and requires that you
> give it an object which implements IFTPShell (with methods like list(),
> makeDirectory(), and openForReading() ). I wrote an implementation of
> IFTPShell that uses Tahoe client calls on the backend.. that's the one in
> Tahoe trunk now.
>
> As Rob pointed out, there is a higher-layer handler in Twisted, in
> twisted/vfs/adapters/ftp.py, which wants an object that implements
> IFileSystem. There are adapters here for both FTP and SFTP, so if we had a
> class that provided IFileSystem and used Tahoe calls on the backend, then we
> could support both protocols.
>
> If I'd looked more closely at the split, I might have written an IFileSystem
> class instead of an IFTPShell class. On the other hand, it turns out I was
> wrong about the FTP server support not being in the latest Twisted release..
> the FTP server in twisted has been around forever, at least as far back as
> 2.4.0. It's the VFS component that is not yet in a release, but we're not
> using that.
>
> On the other other hand, to get FTP uploads to wait until the backend upload
> has actually finished, we need a patch to the FTP code. So, while our
> limitation to FTP (and not SFTP) means we don't need Twisted SVN-HEAD, our
> desire to have 'PUT' wait until the file is actually uploaded and linked
> means that we need to run this code against a patched Twisted-8.1.0 (or any
> other suitable release).
>
> I plan to look into the SFTP/vfs/IFileSystem support soon, maybe next week,
> since I would like us to have SFTP support. I'd like to avoid duplicating
> code with the FTP layer, but on the other hand I don't want to require an
> unreleased version of Twisted to use just the FTP service. Once the next
> Twisted release happens (particularly if I can convince someone to review my
> wait-for-upload patch), things will be a lot better.
>
>
> cheers,
>  -Brian
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