Clear web terminal when session ends #8850
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atburke
requested review from
klizhentas,
r0mant and
russjones
as code owners
lib/client/terminal/terminal_unix.go
Outdated
| @@ -152,6 +152,15 @@ func (t *Terminal) Stderr() io.Writer { | |||
| return t.stderr | |||
| } | |||
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| // Clear clears the terminal, including scrollback. | |||
| func (t *Terminal) Clear() error { | |||
| const resetPattern = "\x1b[3J\x1b\x63\n" | |||
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Maybe leave a comment linking to the source of this escape code so we know where to look if we need to change it?
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Good plan. @gzdunek can you add this?
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I think some of it came from here: https://superuser.com/questions/122911/what-commands-can-i-use-to-reset-and-clear-my-terminal
But the above looks different, @gzdunek how did you arrive at that escape sequence?
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/x1b[3J - clears scrollback (https://newbedev.com/how-do-i-reset-the-scrollback-in-the-terminal-via-a-shell-command https://apple.stackexchange.com/a/187773) - it is needed at least for the Mac terminal
If n is 3, clear entire screen and delete all lines saved in the scrollback buffer (this feature was added for xterm and is supported by other terminal applications)."
\x1b\x63 - clears current screen - same as '\0033\0143' linked above
Add it as a comment?
| @@ -272,6 +272,10 @@ func (t *Terminal) Stderr() io.Writer { | |||
| return t.stderr | |||
| } | |||
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| func (t *Terminal) Clear() error { | |||
| return nil | |||
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Does this need to work on Windows too?
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#6107 only asks for it to work in the web terminal.
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I actually don't know the answer to this, but would this windows terminal not show up in the web UI as well? Is there any reason we shouldn't make it work on Windows?
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We should support all terminals. The Web UI was requested in the ticket, but after talking with the customer, it's a FedRAMP requirement for all terminals.
If the escape code approach works for the Web UI (as in xterm.js understands it) we should just make the changes in lib/client and let all terminals automatically pick it up.
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xtermjs does understand it
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@timothyb89 What does tsh.exe support? Also, any hints on how @atburke could handle this for Windows?
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tsh does enable ANSI processing on Windows, so assuming Terminal.Close() hasn't yet been called (which appears to be the case) I'd expect the usual escape sequence to just work. Microsoft recommends the same: https://docs.microsoft.com/en-us/windows/console/clearing-the-screen
There are other fallback methods involving old Win32 APIs if we really have to, but hopefully we can get the ANSI sequence working.
(Slight possible caveat that the ANSI sequences might not work on very early versions of Windows 10, as in v1609 if not earlier. Hopefully we don't need to worry about them w.r.t compliance issues?)
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I agree, we should not fall back to Win32 or support very early version of Windows 10.
@atburke What version of Windows were you using?
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This was on Windows 10 version 1809.
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I just copied the impl over from terminal_unix.go to terminal_windows.go and it cleared my cmd.exe just fine (on Win10 20H2)
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@timothyb89 Would you mind giving this a review when you have a moment? |
This change clears the screen when an ssh session ends (only in FIPS mode). Note: This doesn't currently do anything in `tsh` on Windows since BoringCrypto isn't supported, but once it is supported, the behavior will match Unix and web. Co-authored-by: Grzegorz <[email protected]> Co-authored-by: Russell Jones <[email protected]>
This change clears the screen when an ssh session ends (only in FIPS mode). Note: This doesn't currently do anything in `tsh` on Windows since BoringCrypto isn't supported, but once it is supported, the behavior will match Unix and web. Co-authored-by: Grzegorz <[email protected]> Co-authored-by: Russell Jones <[email protected]>
This change clears the screen when an ssh session ends (only in FIPS mode). Note: This doesn't currently do anything in `tsh` on Windows since BoringCrypto isn't supported, but once it is supported, the behavior will match Unix and web. Co-authored-by: Grzegorz <[email protected]> Co-authored-by: Russell Jones <[email protected]>
This change clears the screen when an ssh session ends (only in FIPS mode). Note: This doesn't currently do anything in `tsh` on Windows since BoringCrypto isn't supported, but once it is supported, the behavior will match Unix and web. Co-authored-by: Grzegorz <[email protected]> Co-authored-by: Russell Jones <[email protected]>
This change clears the screen when an ssh session ends (only in FIPS mode). Note: This doesn't currently do anything in `tsh` on Windows since BoringCrypto isn't supported, but once it is supported, the behavior will match Unix and web. Co-authored-by: Grzegorz <[email protected]> Co-authored-by: Russell Jones <[email protected]>
This change clears the screen when an ssh session ends (only in FIPS mode). Note: This doesn't currently do anything in `tsh` on Windows since BoringCrypto isn't supported, but once it is supported, the behavior will match Unix and web. Co-authored-by: Grzegorz <[email protected]> Co-authored-by: Russell Jones <[email protected]>
This change clears the screen when an ssh session ends (only in FIPS mode). Note: This doesn't currently do anything in `tsh` on Windows since BoringCrypto isn't supported, but once it is supported, the behavior will match Unix and web. Co-authored-by: Grzegorz <[email protected]> Co-authored-by: Russell Jones <[email protected]>
Only applies when Teleport is compiled for FedRAMP compliance. Closes #6107.