libmsc/gsm_09_11.c: implement guard timer for NCSS sessions

It may happen that either the MS or an EUSE would become
unresponsive during a call independent SS session, e.g.
due to a bug, or a dropped message. In such cases, the
corresponding transaction would remain unfreed forever.

This change introduces a guard timer, that prevents keeping
'stalled' NCSS sessions forever. As soon as it expires, both
sides (i.e. MS and EUSE) are getting notified, and the
transaction is being released.

By default, the timer expires after 30 seconds. As soon as
either the MS, or an EUSE initiates any activity,
the watchdog timer is rescheduled.

The timeout value can be configured from the VTY:

  msc
   ...
   ! Use 0 to disable this timer
   ncss guard-timeout 30

Please note that changing the timeout value at run-time
doesn't affect the existing NCSS sessions, excepting the
case when the timer is disabled at run-time.

This change makes TC_lu_and_ss_session_timeout pass.

Change-Id: Icf4d87c45e90324764073e8230e0fb9cb96dd9cb
Related Change-Id: (TTCN) I3e1791773d56617172ae27a46889a1ae4d400e2f
Related: OS#3655

1 files changed, 15 insertions, 0 deletions

diff --git a/src/libmsc/msc_vty.c b/src/libmsc/msc_vty.c
index 078b83aea..5aa533b1f 100644
--- a/src/libmsc/msc_vty.c
+++ b/src/libmsc/msc_vty.c
@@ -375,6 +375,18 @@ ALIAS_DEPRECATED(cfg_msc_mncc_guard_timeout,
 		 "mncc-guard-timeout <0-255>",
 		 MNCC_GUARD_TIMEOUT_STR MNCC_GUARD_TIMEOUT_VALUE_STR);
 
+#define NCSS_STR "Configure call independent Supplementary Services\n"
+
+DEFUN(cfg_msc_ncss_guard_timeout,
+      cfg_msc_ncss_guard_timeout_cmd,
+      "ncss guard-timeout <0-255>",
+      NCSS_STR "Set guard timer for session activity\n"
+      "guard timer value (sec.), or 0 to disable\n")
+{
+	gsmnet->ncss_guard_timeout = atoi(argv[0]);
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_msc_assign_tmsi, cfg_msc_assign_tmsi_cmd,
       "assign-tmsi",
       "Assign TMSI during Location Updating.\n")
@@ -496,6 +508,8 @@ static int config_write_msc(struct vty *vty)
 		vty_out(vty, " mncc external %s%s", gsmnet->mncc_sock_path, VTY_NEWLINE);
 	vty_out(vty, " mncc guard-timeout %i%s",
 		gsmnet->mncc_guard_timeout, VTY_NEWLINE);
+	vty_out(vty, " ncss guard-timeout %i%s",
+		gsmnet->ncss_guard_timeout, VTY_NEWLINE);
 	vty_out(vty, " %sassign-tmsi%s",
 		gsmnet->vlr->cfg.assign_tmsi? "" : "no ", VTY_NEWLINE);
 
@@ -1588,6 +1602,7 @@ void msc_vty_init(struct gsm_network *msc_network)
 	install_element(MSC_NODE, &cfg_msc_mncc_external_cmd);
 	install_element(MSC_NODE, &cfg_msc_mncc_guard_timeout_cmd);
 	install_element(MSC_NODE, &cfg_msc_deprecated_mncc_guard_timeout_cmd);
+	install_element(MSC_NODE, &cfg_msc_ncss_guard_timeout_cmd);
 	install_element(MSC_NODE, &cfg_msc_no_assign_tmsi_cmd);
 	install_element(MSC_NODE, &cfg_msc_auth_tuple_max_reuse_count_cmd);
 	install_element(MSC_NODE, &cfg_msc_auth_tuple_reuse_on_error_cmd);