Bug 436919

Description of problem:
eggcups segfaults if remote printer hostname contains _ character, '_'.

Version-Release number of selected component (if applicable):
desktop-printing-0.19-20.el5

How reproducible:
100%

Steps to Reproduce:
Set up a remote printer using ipp to a host that has a _ in the name. For
example: http://SIE_INFO_4/printers/queue1
Sent a print job to the queue and watch eggcups crash with a segfault.

Actual results:
segfault in g_str_hash

Expected results:
No segfault

Additional info:
Here is an example stack trace of a faulting process (rhel4):

(gdb) bt
#0  0x000000308433d8c0 in g_str_hash () from /usr/lib64/libglib-2.0.so.0
#1  0x000000308431c849 in g_hash_table_lookup () from /usr/lib64/libglib-
2.0.so.0
#2  0x000000000040dc42 in ec_cups_job_monitor_add_job (mon=0x5275a0, poll_now=1,
   host=0x0, printer_path=0x5d43c0 "/printers/Kopierer", job_id=35)
   at ec-cups-job-monitor.c:546
#3  0x000000000040ef41 in ec_job_model_job_sent_remote (model=0x527eb0,
   printer_name=0x5d4020 "remote", local_job_id=20,
   printer_uri=0x5d43c0 "/printers/Kopierer", remote_job_id=35)
   at ec-job-model.c:547
#4  0x0000000000412ef2 in handle_generic_dbus_message (icon=0x5a0460,
   is_session=0, connection=0x0, message=0x5a5690) at ec-tray-icon.c:530
#5  0x0000003085f0fd23 in dbus_connection_dispatch ()
  from /usr/lib64/libdbus-1.so.0
#6  0x000000308ac05cd8 in dbus_g_connection_flush ()
  from /usr/lib64/libdbus-glib-1.so.0
#7  0x00000030843266bd in g_main_context_dispatch ()
  from /usr/lib64/libglib-2.0.so.0
#8  0x0000003084328397 in g_main_context_acquire ()
  from /usr/lib64/libglib-2.0.so.0
#9  0x0000003084328735 in g_main_loop_run () from /usr/lib64/libglib-2.0.so.0
#10 0x0000003088818511 in gtk_main () from /usr/lib64/libgtk-x11-2.0.so.0
#11 0x000000000040b5d9 in main (argc=5, argv=0x5367c0) at main.c:206

From the stack trace above you can see that "host" passed to
ec_cups_job_monitor_add_job() is a null pointer and it is this which gets passed
on to the hash functions and results in the segfault.

"host" is assigned in ec_job_model_job_sent_remote using values that are
returned from xmlParseURI. Its possible for xmlParseURI to return without error
but with a struct that isn't populated correctly.

The attached patch adds additional checks to xmluri.