FS#43867 - [xorg-server-xephyr] "XDMCP fatal error: Session declined %*.*s"

Attached to Project: Arch Linux
Opened by Voob Scout (voobscout) - Wednesday, 18 February 2015, 07:51 GMT
Last edited by Laurent Carlier (lordheavy) - Tuesday, 16 June 2015, 17:47 GMT
Task Type Bug Report
Category Upstream Bugs
Status Closed
Assigned To Jan de Groot (JGC)
Andreas Radke (AndyRTR)
Laurent Carlier (lordheavy)
Architecture x86_64
Severity High
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 1
Private No

Details

Description:
XDMCP fatal error: Session declined %*.*s

This has not happened before, started to happen after update to latest version.

No configuration changes were performed on the side of xdmcp.
Other xdmcp clients continue to connect happily to the same server.

Not really sure if it's an upstream bug or something with packaging, incase it's an upstream, could some gentle sole perhaps direct me to xorg bug tracking, so i can file upstream. Thanks!

Additional info:
* package version 1.17.1-1
* running "Xephyr :12 -ac -screen 800x600 -query 127.0.0.1"

(EE)
Fatal server error:
(EE) (EE) BUG: triggered 'if (f[f_idx])'
(EE) BUG: log.c:475 in vpnprintf()
(EE) Unsupported printf directive '*'
(EE)
(EE) Backtrace:
(EE) 0: Xephyr (xorg_backtrace+0x56) [0x5ab4f6]
(EE) 1: Xephyr (0x400000+0x1b820f) [0x5b820f]
(EE) 2: Xephyr (LogVMessageVerbSigSafe+0x4d) [0x5b8a9d]
(EE) 3: Xephyr (FatalError+0xea) [0x5b857a]
(EE) 4: Xephyr (0x400000+0x1bab02) [0x5bab02]
(EE) 5: Xephyr (0x400000+0x1baf15) [0x5baf15]
(EE) 6: Xephyr (WakeupHandler+0x6b) [0x4755cb]
(EE) 7: Xephyr (WaitForSomething+0x1c3) [0x5a87f3]
(EE) 8: Xephyr (0x400000+0x70731) [0x470731]
(EE) 9: Xephyr (0x400000+0x74a8b) [0x474a8b]
(EE) 10: /usr/lib/libc.so.6 (__libc_start_main+0xf0) [0x7f454c17e800]
(EE) 11: Xephyr (_start+0x29) [0x429369]
(EE)
XDMCP fatal error: Session declined %*.*s
(EE)


Steps to reproduce:
# Xephyr :12 -ac -screen 800x600 -query 127.0.0.1
(ofcourse one needs a working xdmcp provider, ie. lightdm/gdm/xdm)
This task depends upon

Closed by  Laurent Carlier (lordheavy)
Tuesday, 16 June 2015, 17:47 GMT
Reason for closing:  Fixed
Comment by Laurent Carlier (lordheavy) - Wednesday, 18 February 2015, 08:11 GMT
Can you try to rebuild and test xorg-server with this unofficial patch applied? http://patchwork.freedesktop.org/patch/40869/

Thanks
Comment by Voob Scout (voobscout) - Wednesday, 18 February 2015, 08:21 GMT
I'd be happy to, but just to clarify the steps i need to take:

1. Get sources and PKGBUILDs with pbget for xephyr and it's reqs.
2. Alter prepare() to include the patch 40869.
3. Rebuild and try running it.

Did I miss something or am I completely off-base here?

P.S. I've switched to arch rather recently...
Comment by Laurent Carlier (lordheavy) - Wednesday, 18 February 2015, 08:32 GMT
You can find packages with patch applied here:
http://pkgbuild.com/~lcarlier/test/
Comment by Voob Scout (voobscout) - Wednesday, 18 February 2015, 09:19 GMT
Tried it with your builds, now it just says:

(EE)
Fatal server error
(EE) XDMCP fatal error: Session declined No valid address found
(EE)
Comment by Laurent Carlier (lordheavy) - Wednesday, 18 February 2015, 11:04 GMT
Please note that with xorg-server-1.17, xserver isn't listening tcp anymore, and probably could result in your error
Comment by Voob Scout (voobscout) - Wednesday, 18 February 2015, 11:12 GMT
afaik xorg-server doesn't listen to tcp by default, ie. it always gets executed with no listen tcp switch.
ie. "/usr/lib/xorg-server/Xorg :0 -seat seat0 -auth /run/lightdm/root/:0 -nolisten tcp vt1 -novtswitch"

Also, it's lightdm that's actually listening on port 177 for xdmcp queries, so I fail to understand your comment. Could you please clarify what you ment by it?
Comment by Voob Scout (voobscout) - Wednesday, 18 February 2015, 13:59 GMT
After a little investigation, it appears that this is a bug upstream https://bugs.freedesktop.org/show_bug.cgi?id=66862 and a well known one at that.

For me personally, this is a show stopper. Likely for lots of other people as well.

Perhaps the xorg-server should be rolled back to the version that did work?
Comment by Laurent Carlier (lordheavy) - Wednesday, 18 February 2015, 14:59 GMT
Can you test the new version (1.2) which have an additionnal patch?
Comment by Voob Scout (voobscout) - Wednesday, 18 February 2015, 15:58 GMT
I'm sorry to report, but the problem persists.
Exactly the same error message.

XDMCP fatal error: Session declined No valid address found
Comment by Voob Scout (voobscout) - Monday, 23 February 2015, 10:12 GMT
The issue appears to be the fact that xorg is being compiled with "-nolisten tcp" option as default.
This fact should probably have made it into some errata or changelog or somesuch docu.

Use "-listen tcp -query [XDMCP host IP]" and it'll be fine.

This should be closed.

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