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

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. 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 by returning early, but it seems to be the fixup part: 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 much 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