Vinagre closes connection to tightvncserver 2.0 beta4 immediately

[mmayer]

===============================
SRU Justification:
1. Impact: vinagre fails to connect to tightvncserver
2. How bug was addressed: a one-line (one-character) fix was pulled from upstream which fixes the initial protocol greeting to include a newline (it was a NULL)
3. Minimal patch: see attached gtk-vnc.debdiff
4. TEST CASE: start tightvncserver, then try to connect to it with vinagre
5. Regression potential: It could break connections from/to other vnc clients/servers. Connections should be tested between all, including 'kvm -vnc'.

Binary package hint: vinagre

Ubuntu 10.04 (Lucid), Vinagre 2.30.2-0ubuntu1
When I connect to a TightVNC-Server 2.0 beta4 the conntection closes immediately with
"Connection to host <ip> was closed."
Other VNC-Viewers are working without a problem.

SRU Justification:
Bug prevents gtk-vnc based clients from working with upcoming tightvncserver releases.

Risk of regression:
Low, patch is a one-line change from upstream only affecting the version string sent in response to the server.

Testcase:
1) Install tightvncserver v2 (not yet in Ubuntu or Debian repositories, alas)
2) start tightvncserver session
3) connect to it with vinagre or another gtk-vnc client; client should attach successfully.

[xplod (xplod83)]

Binary package hint: vinagre

Ubuntu 10.04 (Lucid), Vinagre 2.30.2-0ubuntu1

Similar to the Problem of TightVNC-Server 2.0 Release in the log file TightVNC-Server says "Invalid format of the RFB version message".
Using Remmina xtightvncviewer and everything works.

[mccurly (mccurly)]

today i sniffed the traffic and compared the handshake from tsclient and vinagre.
the handshake from vinagre seems not to work as specified in the rfb protocol.
see: http://datatracker.ietf.org/doc/draft-levine-rfb/

summarized protocol v.3.8 handshake:
server tells highest protocol version on connection: "RFB 003.008\n" (hex 52 46 42 20 30 30 33 2e 30 30 38 0a)
client tells it version, too: "RFB 003.008\n" (hex 52 46 42 20 30 30 33 2e 30 30 38 0a)

but vinagres reply to the server is "RFB 003.008 " (hex 52 46 42 20 30 30 33 2e 30 30 38 00)

the end of the string differs from vinagre (hex: 00) and tsclient (hex: 0a).

v1.x servers of tightvnc just seem to take the rfb-string "RFB 003.008" without newline at the end.
v2.x servers of tightvnc seem to read all of the reply, includeing the last character

that's why, i guess, the server logs "Invalid format of the RFB version message"

maybe thats the point.

someone has to investigate this.

tested on:
lucid:
tsclient: 0.150
vinagre: 2.30.2
winxp pro sp3:
tightvnc-server 1.3.10
tightvnc-server 2.0.2

[Jonh Wendell (wendell)]

This issue has been fixed a while ago: http://git.gnome.org/browse/gtk-vnc/commit/?id=bc9e2b19167686dd381a0508af1a5113675d08a2

[mccurly (mccurly)]

thanks for the hint!
i managed to modify the original ubuntu package (gtk-vnc_0.3.10.orig.tar.gz) and test it. works out for me, now.
i am not really familiar to packageing, but here are the lines i changed to get it work. hope this helps.

[Tom Henderson (tomhenderson)]

I notice that a fix was identified some time ago, but I don't see where this has been added to the current or any future releases of vinagre. Are there any plans to include this fix in a package?

[Anand Kumria (wildfire)]

This is an off-by-one snprintf fix; I think this warrants being backported to Ubuntu 10.04 LTS (Lucid)

[Anand Kumria (wildfire)]

In Lucid's case the file is src/gvnc.c but I can confirm it works when gtk-vnc is rebuilt.

[Steve Beattie (sbeattie)]

Correcting the package this bug is against from vinagre to gtk-vnc, since that's where the underlying problem is. Attached is a debdiff based on the diffs pointed out by Josh Wendell and mccurrly above for a lucid SRU.

[Dave Walker (davewalker)]

Uploaded debdiff from comment #8, awaiting SRU approval.

[Martin Pitt (pitti)]

I verified that the fix is in oneiric.

[Martin Pitt (pitti)]

Hello mmayer, or anyone else affected,

Accepted gtk-vnc into lucid-proposed, the package will build now and be available in a few hours. Please test and give feedback here. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you in advance!

[Anand Kumria (wildfire)]

Confirming that this works against tightvnc servers (running Windows XP / Windows Vista / Windows 7) - which is what I tested against.

[Launchpad Janitor (janitor)]

This bug was fixed in the package gtk-vnc - 0.3.10-2ubuntu2.1

---------------
gtk-vnc (0.3.10-2ubuntu2.1) lucid-proposed; urgency=low

  * Fix off-by-one error in snprintf call generating the version
    string, thanks to Josh Wendell and mccurlly for identifying the
    fix (LP: #598597)
    - add debian/patches/0006-fix-snprintf-off-by-1-lp598597.patch
    - update debian/patches/series
 -- Steve Beattie <email address hidden> Mon, 15 Aug 2011 11:31:15 -0700