openssh bugs - Jan 2015 - [Bug 2338] New: scp -3 doesn't give an error on missing source directory

https://bugzilla.mindrot.org/show_bug.cgi?id=2338

            Bug ID: 2338
           Summary: scp -3 doesn't give an error on missing source
                    directory
           Product: Portable OpenSSH
           Version: 6.7p1
          Hardware: Other
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P5
         Component: scp
          Assignee: unassigned-bugs at mindrot.org
          Reporter: jjelen at redhat.com

This bug was created as a copy from RHBZ#1159307
(https://bugzilla.redhat.com/show_bug.cgi?id=1159307)
------------------------------------------------
Description of problem:

scp -3r a:foo user at b:

foo didn't exist, but scp gave no error message.

(a and b are rhel7 boxen, also seems to happen if a is rhel5, so I
think it's actually the client end, which is my f21 laptop)

Version-Release number of selected component (if applicable):
openssh-clients-6.6.1p1-5.fc21.1.x86_64 (my laptop)
openssh-server-6.4p1-8.el7.x86_64 (RHEL7 host a and b)

How reproducible:
100%

Steps to Reproduce:
1. scp -3r a:foo b:
    where foo doesn't exist

Actual results:
Apparent success

Expected results:
An error, since foo didn't exist on the source

Additional info:
adding -v shows:

Sink: scp: foo: No such file or directory


Comment 1 Jakub Jelen 2015-01-14 10:21:51 CET

I tried this use case also with upstream release and it behaves the
same.

In man page of scp, there is note:
> Note that this option disables the progress meter.
And I would say that this issue is related to this note, because the
file transfer is made through the local host and the inputs and outputs
of both remote commands are connected (but it doesn't change the thing
that stderr should output).

All the behaviour of -3 option is quite strange, since the errors from
source system are written only with -v option and errors from target
system are never written.

I can try to place the question into openssh bugzilla, but upstream is
not much willing to maintain scp.

For more information, this feature is related to this bugzilla [1], but
without much discussion.

[1] https://bugzilla.mindrot.org/show_bug.cgi?id=1837

------------------------------------------------

Not sure if it is feature or bug. I would like to get some opinion or
clarification from the authors.

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--- Comment #1 from Jakub Jelen <jjelen at redhat.com> ---
Created attachment 2600
  --> https://bugzilla.mindrot.org/attachment.cgi?id=2600&action=edit
Patch to show errors from remote ends

To catch up with Red Hat bugzilla: Implementation of extended remote to
remote is sending error messages back and forth from one remote to the
other and none of them is writing them out. It seems half-baked.
This can be solved by catching such messages in initiator process (or
writing them out in the remote processes, but it requires changes on
server side).

After some digging in this case I managed to make stream redirection
and catching errors in the initiator process. This change doesn't
require any changes on server side so there are no drawbacks about
backward compatibility.

For now it is fully functional implementation. Some notes for future
self (or anyone having look into it):
 * Follows scp state protocol in simple FSM
 * It would be nicer to use atomicio everywhere (I read all line
instead of reading byte after byte as implementation on server side)
 * Progress-meter is working again
 * Still doesn't work using password authentication on both ends, since
the prompts are print over each other.
 * There is some overhead, but if you aim for speed you will not use -3
option

I tried my best to come up with quality code, but feel free to comment
if you find some problem or something is not clear. Patch can be
applied to upstream sources

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Jakub Jelen <jjelen at redhat.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jrwren at xmtp.net

--- Comment #2 from Jakub Jelen <jjelen at redhat.com> ---
*** Bug 2761 has been marked as a duplicate of this bug. ***

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |WONTFIX
                 CC|                            |djm at mindrot.org

--- Comment #3 from Damien Miller <djm at mindrot.org> ---
We're moving away from rcp-based scp, and the new sftp-based scp does
show the error message

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED

--- Comment #4 from Damien Miller <djm at mindrot.org> ---
Closing bugs from OpenSSH 9.1 release cycle

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