[sr-dev] app_python: call_function "append_hf" with more than 1 param crashes kamailio

[Konstantin M.]

Hi,
Could you please tell me the chunk of code that illustrates this problem?
Thanks!



2014-07-16 14:10 GMT+04:00 Örn Arnarson <orn at arnarson.net>:

> Resent after signing up, due to original message being held for review for
> a week:
>
> Kamailio terminates (Signal 15) after app_python crashes (signal 7) when
> using call_function("append_hf") with more than 1 parameter.
>
> Jul  9 13:53:18 vcr01 /usr/sbin/kamailio[2699]: ALERT: <core>
> [main.c:788]: handle_sigs(): child process 2707 exited by a signal 7
> Jul  9 13:53:18 vcr01 /usr/sbin/kamailio[2699]: ALERT: <core>
> [main.c:791]: handle_sigs(): core was generated
> Jul  9 13:53:18 vcr01 /usr/sbin/kamailio[2699]: INFO: <core> [main.c:803]:
> handle_sigs(): INFO: terminating due to SIGCHLD
> Jul  9 13:53:18 vcr01 /usr/sbin/kamailio[2706]: INFO: <core> [main.c:854]:
> sig_usr(): INFO: signal 15 received
>
> Actually, calling "remove_hf" with call_function seems to do exactly the
> same thing, though that is just with 1 param.
>
> My problem is that I need to manipulate the Diversion headers (or rather,
> add a new Diversion header in the correct place (i.e. above the other
> Diversion header), as append_hf will always add it at the bottom.)
>
> I've identified what part of the code makes it crash (debugging by
> returning early), and it seems to be the fixup part, which as far as I can
> tell has something to do with string formatting for kamailio:
>     if (fexport->fixup != NULL) {
>         if (i >= 3) {
>             rval = fexport->fixup(&(act->val[3].u.data), 2);
>             if (rval < 0) {
>                 PyErr_SetString(PyExc_RuntimeError, "Error in fixup (2)");
>                 Py_INCREF(Py_None);
>                 return Py_None;
>             }
>             act->val[3].type = MODFIXUP_ST;
>         }
>         if (i >= 2) {
>             rval = fexport->fixup(&(act->val[2].u.data), 1);
>             if (rval < 0) {
>                 PyErr_SetString(PyExc_RuntimeError, "Error in fixup (1)");
>                 Py_INCREF(Py_None);
>                 return Py_None;
>             }
>             act->val[2].type = MODFIXUP_ST;
>         }
>         if (i == 1) {
>             rval = fexport->fixup(0, 0);
>             if (rval < 0) {
>                 PyErr_SetString(PyExc_RuntimeError, "Error in fixup (0)");
>                 Py_INCREF(Py_None);
>                 return Py_None;
>             }
>         }
>     }
>
> I have very little experience with programming in C, and even less
> debugging with gdb or something similar, but from comparing this code with
> the way the Perl module does this, I couldn't see any obvious problems. I'm
> hoping someone with familiarity with the kamailio functions, such as fixup,
> might be able to identify the problem.
>
> Judging from the exit code of app_python, my (uninformed) guess would be
> that there's an attempt to access or manipulate something in an
> out-of-scope memory address.
>
> Any suggestions would be greatly appreciated. I've written a quite large
> routing function in python and I'd like to avoid rewriting it in a
> different scripting language if possible.
>
> The kamailio version I'm running is 4.0.4
>
> Regards,
> Örn
>
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