openssh bugs - Mar 2018 - [Bug 2836] New: Send terminfo description over the wire on login

https://bugzilla.mindrot.org/show_bug.cgi?id=2836

            Bug ID: 2836
           Summary: Send terminfo description over the wire on login
           Product: Portable OpenSSH
           Version: 7.6p1
          Hardware: All
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P5
         Component: sshd
          Assignee: unassigned-bugs at mindrot.org
          Reporter: docwhat at gerf.org

I?ve been running into problems with terminfo descriptions not existing
on machines I?m SSH?ing to.

Example: My laptop has TERM=tmux-256color but a RHEL6 box I connect to
does not; I have to choose a lesser term (e.g. screen-256color) or
manually do `infocmp -x` (local) and `tic -x` (remote) to fix it.

Is there a reason that SSH client couldn?t do something like this?

Any ?no? will abort these steps and continue with a normal session.

1. Do you support terminfo/ncurses?
2. Are you missing TERM=$TERM?
3. Here is the terminfo description for $TERM.

On the server side, it could have builtin support to do `tic -x`.  It
should force it to write to the terminfo database in the users home
directory (even if root!).

Alternatively to prevent terminal collisions, it could store the
terminfo database in a private temporary directory, set the TERMINFO
variable to point at that directory, and remove the private temporary
directory when the SSH session closes.

Or maybe it could save it as something like SSH-<session-id>-$TERM and
force the TERM to that and remove that entry when the session is over.

This would be a huge usability win for people who have to deal with
various platforms and versions.

Ciao!

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Christian H?ltje <docwhat at gerf.org> changed:

           What    |Removed                     |Added
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                 CC|                            |docwhat at gerf.org

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
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                 CC|                            |djm at mindrot.org

--- Comment #1 from Damien Miller <djm at mindrot.org> ---
I don't know whether terminal definitions are guaranteed to be
exportable/importable between systems. In practice they work between
systems that use ncurses, but that's not a sure thing.

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--- Comment #2 from Christian H?ltje <docwhat at gerf.org>
---
> I don't know whether terminal definitions are guaranteed to be
exportable/importable between systems.
terminfo is by design compatible between any system (that uses
terminfo).
> In practice they work between systems that use ncurses, but that's not
a sure thing.
During compilation if you detect terminfo, then turn on sending or
receiving terminfo capabilities.

During connection negotiation, the client can ask the remote server if
they support terminfo; if true, then send the terminfo capabilities.

Assuming a TTY is allocated, the server can write the capabilities to a
file and set the TERMINFO environment variable pointing at that file.


Also, just to be clear, terminfo is used by ncurses, but (in theory) it
is separate.  In practice it usually isn't.

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Damien Miller <djm at mindrot.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |WONTFIX

--- Comment #3 from Damien Miller <djm at mindrot.org> ---
Sorry, but I think that this would be significantly complex and
relatively fragile. Too much so for the small benefit it IMO provides.

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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 resolved bugs as of 8.6p1 release

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