sccp: Notify users of point code available/unavailable

* add N-PCSTATE.ind and N-STATE.ind definitions to SCCP user SAP
* add minimal SCMG (SCCP Management) and LBCS (Local Broadcast)
* generate MTP-PAUSE.ind/MTP-RESUME.ind based on received xUA DUNA/DAVA
* generate N-PCSTATE.ind towards the local SCCP users

Change-Id: Idb799f7d7ab329ad12f07b7cbe6336da0891ae92
Related: OS#2623, OS#3403, OS#4701

1 files changed, 83 insertions, 0 deletions

diff --git a/src/sccp_scmg.c b/src/sccp_scmg.c
new file mode 100644
index 0000000..4a8ccf6
--- /dev/null
+++ b/src/sccp_scmg.c
@@ -0,0 +1,83 @@
+/* SCCP Management (SCMG) according to ITU-T Q.713/Q.714 */
+
+/* (C) 2021 by Harald Welte <laforge@gnumonks.org>
+ * All Rights reserved
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <string.h>
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/core/fsm.h>
+
+#include <osmocom/sigtran/sccp_sap.h>
+#include <osmocom/sigtran/protocol/sua.h>
+#include <osmocom/sccp/sccp_types.h>
+
+#include "xua_internal.h"
+#include "sccp_internal.h"
+
+/*! brief MTP -> SNM (MTP-PAUSE.ind) - inability to providing MTP service Q.714 5.2.2 */
+void sccp_scmg_rx_mtp_pause(struct osmo_sccp_instance *inst, uint32_t dpc)
+{
+	struct osmo_scu_pcstate_param pcstate;
+	/* 1) Informs the translation function to update the translation tables. */
+	/* 2) SCCP management marks as "prohibited" the status of the remote signalling point, the
+	   remote SCCP and each subsystem at the remote signalling point. */
+	/* 3) Discontinues all subsystem status tests (including SSN = 1) */
+
+	/* 4) local broadcast of "user-out-of-service" for each SSN at that dest
+	 * [this would require us to track SSNs at each PC, which we don't] */
+
+	/* 5) local broadcast of "signaling point inaccessible" */
+	/* 6) local broadcast of "remote SCCP unavailable" */
+	pcstate = (struct osmo_scu_pcstate_param) {
+		.affected_pc = dpc,
+		.restricted_importance_level = 0,
+		.sp_status = OSMO_SCCP_SP_S_INACCESSIBLE,
+		.remote_sccp_status = OSMO_SCCP_REM_SCCP_S_UNAVAILABLE_UNKNOWN,
+	};
+	sccp_lbcs_local_bcast_pcstate(inst, &pcstate);
+}
+
+/*! brief MTP -> SNM (MTP-RESUME.ind) - ability of providing the MTP service Q.714 5.2.3 */
+void sccp_scmg_rx_mtp_resume(struct osmo_sccp_instance *inst, uint32_t dpc)
+{
+	struct osmo_scu_pcstate_param pcstate;
+	/* 1) Sets the congestion state of that signalling point */
+	/* 2) Instructs the translation function to update the translation tables. */
+	/* 3) Marks as "allowed" the status of that destination, and the SCCP */
+	/* 4) - not applicable */
+	/* 5) Marks as "allowed" the status of remote subsystems */
+
+	/* 6) local broadcast of "signalling point accessible" */
+	/* 7) local broadcast of "remote SCCP accessible" */
+	pcstate = (struct osmo_scu_pcstate_param) {
+		.affected_pc = dpc,
+		.restricted_importance_level = 0,
+		.sp_status = OSMO_SCCP_SP_S_ACCESSIBLE,
+		.remote_sccp_status = OSMO_SCCP_REM_SCCP_S_AVAILABLE,
+	};
+	sccp_lbcs_local_bcast_pcstate(inst, &pcstate);
+
+	/* 8) local broadcast of "user-in-service"
+	 * [this would require us to track SSNs at each PC, which we don't] */
+}