[FreeNX-kNX] nxagent session gets lost, user gets new session even though one already exists

[Mario Becroft]

Here is some more info. I think someone who understands how the
nxserver/nxnode interaction is supposed to function can figure out the
problem from the following debug output. I found that part of the reason
for the confusing nxnode output is because there are in fact two
nxnode's running. You can distinguish between them in the debug output
below by looking at the pid. The one that emits the "1001 Bye" with no
delimiter is the one invoked with "--slave". The other one was invoked
with "--startsession".

The NNNN lines are emitted by nxnode, and trace when it is starts, stops
and emits messages about the session state.

The other lines are from nxserver. They have my added instrumentation at
the beginning of the line showing the process name, pid and time. The
ones with AAAA are my additional instrumentation. The "AAAA cmd=..."
line prints all commands received by the loop inside
server_nxnode_start_wait(). It is interesting to note that in the
failure case, it never sees the "suspending" and "suspended" messages.

The main difference is that when the failure occurs,
server_nxnode_start_wait() reads EOF and the session gets closed. The
message "AAAA method is su, done nxnode_login" is where nxnode_login
invoking su has returned inside server_nxnode_start. When you suspend
the session correctly, this does not happen.

Please help! I will be doing more work on this tomorrow.

Output when suspending the session in the proper way, so that there is
no fault:

--8<---------------cut here---------------start------------->8---
NNNN(/usr/NX/bin/nxnode)(12567)(Sat Jan 24 18:07:30 NZDT 2009) saying that session status is suspending
(/usr/NX/bin/nxserver)(12050)(Sat Jan 24 18:07:30 NZDT 2009) nxnode_reader: NX> 1009 Session status: suspending
NX> 1009 Session status: suspending
(/usr/NX/bin/nxserver)(12050)(Sat Jan 24 18:07:30 NZDT 2009) AAAA cmd=(NX> 1009 Session status: suspending)
(/usr/NX/bin/nxserver)(12050)(Sat Jan 24 18:07:30 NZDT 2009) session_status 89E5FFF02E9C82347C7085AD85DF24DC Suspending
(/usr/NX/bin/nxserver)(12050)(Sat Jan 24 18:07:30 NZDT 2009) server_nxnode_echo: NX> 1009 Session status: suspending
NNNN(/usr/NX/bin/nxnode)(12567)(Sat Jan 24 18:07:31 NZDT 2009) saying that session status is suspended
(/usr/NX/bin/nxserver)(12050)(Sat Jan 24 18:07:31 NZDT 2009) Info: Closing connection to slave with pid 12188.
(/usr/NX/bin/nxserver)(12050)(Sat Jan 24 18:07:31 NZDT 2009) nxnode_reader: NX> 1005 Session status: suspended
NX> 1005 Session status: suspended
NNNN(/usr/NX/bin/nxnode)(12200)(Sat Jan 24 18:07:31 NZDT 2009) stopping, delim is ()
(/usr/NX/bin/nxserver)(12050)(Sat Jan 24 18:07:31 NZDT 2009) AAAA cmd=(NX> 1005 Session status: suspended)
(/usr/NX/bin/nxserver)(12050)(Sat Jan 24 18:07:31 NZDT 2009) nxnode_reader: 1001 Bye.
1001 Bye.
(/usr/NX/bin/nxserver)(12050)(Sat Jan 24 18:07:31 NZDT 2009) session_suspend 89E5FFF02E9C82347C7085AD85DF24DC
(/usr/NX/bin/nxserver)(12050)(Sat Jan 24 18:07:31 NZDT 2009) server_nxnode_echo: NX> 1005 Session status: suspended
--8<---------------cut here---------------end--------------->8---

Output when killing nxssh on the client, resulting in nxagent
automatically suspending the session, but causing the fault condition:

--8<---------------cut here---------------start------------->8---
(/usr/NX/bin/nxserver)(9867)(Sat Jan 24 17:43:48 NZDT 2009) Info: Closing connection to slave with pid 10009.
NNNN(/usr/NX/bin/nxnode)(10021)(Sat Jan 24 17:43:48 NZDT 2009) stopping, delim is ()
(/usr/NX/bin/nxserver)(9867)(Sat Jan 24 17:43:48 NZDT 2009) nxnode_reader: 1001 Bye.
1001 Bye.
NNNN(/usr/NX/bin/nxnode)(10416)(Sat Jan 24 17:43:48 NZDT 2009) saying that session status is suspending
(/usr/NX/bin/nxserver)(9867)(Sat Jan 24 17:43:48 NZDT 2009) AAAA cmd=(1001 Bye.)
NNNN(/usr/NX/bin/nxnode)(10416)(Sat Jan 24 17:43:48 NZDT 2009) saying that session status is suspended
(/usr/NX/bin/nxserver)(9867)(Sat Jan 24 17:43:48 NZDT 2009) nxnode_reader: NX> 596 Error: Session  failed. Reason was: Session: Display failure detected at 'Sat Jan 24 17:43:48 2009'.
(/usr/NX/bin/nxserver)(9867)(Sat Jan 24 17:43:48 NZDT 2009) nxnode_reader: NX> 1009 Session status: suspending
(/usr/NX/bin/nxserver)(9867)(Sat Jan 24 17:43:48 NZDT 2009) AAAA method is su, done nxnode_login
(/usr/NX/bin/nxserver)(9867)(Sat Jan 24 17:43:48 NZDT 2009) AAAA end of server_nxnode_start
(/usr/NX/bin/nxserver)(9867)(Sat Jan 24 17:43:48 NZDT 2009) AAAA server_nxnode_start_wait about to close session
(/usr/NX/bin/nxserver)(9867)(Sat Jan 24 17:43:48 NZDT 2009) AAAA nxnode_login_stop_slave call 3
(/usr/NX/bin/nxserver)(9867)(Sat Jan 24 17:43:48 NZDT 2009) Info: Closing connection to slave with pid 10009.
--8<---------------cut here---------------end--------------->8---

-- 
Mario Becroft <mb at gem.win.co.nz>