[tahoe-lafs-trac-stream] [tahoe-lafs] #1442: scp fails silently when copying to a Tahoe SFTP frontend; it should fail loudly

[tahoe-lafs]

#1442: scp fails silently when copying to a Tahoe SFTP frontend; it should fail
loudly
-------------------------------+------------------------------------------
     Reporter:  davidsarah     |      Owner:  kevan
         Type:  defect         |     Status:  assigned
     Priority:  major          |  Milestone:  1.9.0
    Component:  code-frontend  |    Version:  1.8.2
   Resolution:                 |   Keywords:  scp error sftp review-needed
Launchpad Bug:                 |
-------------------------------+------------------------------------------
Description changed by davidsarah:

Old description:

> Our SFTP frontend does not support {{{scp}}}, which is fine ({{{scp}}}
> tries to open a shell over the SSH connection, rather than using SFTP,
> and the set of commands that it can issue to that shell is not well-
> defined).
>
> However, it isn't fine that it fails silently. This is probably a bug in
> {{{scp}}} rather than Tahoe, since Tahoe ''does'' report an error to the
> client when it tries to open a shell or issue unknown commands: lines
> 1873 and 1888 [source:src/allmydata/frontends/sftpd.py at 4999#L1857 here].
> (We need to accept shell connections in order to support the {{{df}}}
> command used by sshfs.) We ''might'' be able to get {{{scp}}} to fail
> loudly by reporting a different error, though.

New description:

 Our SFTP frontend does not support {{{scp}}}, which is fine ({{{scp}}}
 tries to open a shell over the SSH connection, rather than using SFTP, and
 ~~the set of commands that it can issue to that shell is not well-
 defined~~ we don't implement
 [http://blogs.oracle.com/janp/entry/how_the_scp_protocol_works the
 protocol it uses]).

 However, it isn't fine that it fails silently. This is probably a bug in
 {{{scp}}} rather than Tahoe, since Tahoe ''does'' report an error to the
 client when it tries to open a shell or issue unknown commands: lines 1873
 and 1888 [source:src/allmydata/frontends/sftpd.py at 4999#L1857 here]. (We
 need to accept shell connections in order to support the {{{df}}} command
 used by sshfs.) We ''might'' be able to get {{{scp}}} to fail loudly by
 reporting a different error, though.

--

-- 
Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1442#comment:8>
tahoe-lafs <http://tahoe-lafs.org>
secure decentralized storage