Implement AoIP, port to M3UA SIGTRAN (large addition and refactoring)

This was originally a long series of commits converging to the final result
seen in this patch. It does not make much sense to review the smaller steps'
trial and error, we need to review this entire change as a whole.

Implement AoIP in osmo-msc and osmo-bsc.

Change over to the new libosmo-sigtran API with support for proper
SCCP/M3UA/SCTP stacking, as mandated by 3GPP specifications for the IuCS and
IuPS interfaces.

From here on, a separate osmo-stp process is required for SCCP routing between
OsmoBSC / OsmoHNBGW <-> OsmoMSC / OsmoSGSN

jenkins.sh: build from libosmo-sccp and osmo-iuh master branches now for new
M3UA SIGTRAN.

Patch-by: pmaier, nhofmeyr, laforge
Change-Id: I5ae4e05ee7c57cad341ea5e86af37c1f6b0ffa77

1 files changed, 76 insertions, 0 deletions

diff --git a/include/openbsc/a_iface.h b/include/openbsc/a_iface.h
new file mode 100644
index 000000000..149f1c71e
--- /dev/null
+++ b/include/openbsc/a_iface.h
@@ -0,0 +1,76 @@
+/* (C) 2017 by Sysmocom s.f.m.c. GmbH
+ * All Rights Reserved
+ *
+ * Author: Philipp Maier
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#pragma once
+
+#include <openbsc/a_reset.h>
+
+/* A struct to keep a context information about the BSCs we are associated with */
+struct bsc_context {
+	struct llist_head list;
+
+	/* Holds a copy of the sccp address of the BSC,
+	 * this address will become known as soon as
+	 * a remote BSC tries to make a connection or
+	 * sends a RESET request via UNIDATA */
+	struct osmo_sccp_addr bsc_addr;
+
+	/* Holds a copy of the our local MSC address,
+	 * this will be the sccp-address that is associated
+	 * with the A interface */
+	struct osmo_sccp_addr msc_addr;
+
+	/* A pointer to the reset handler FSM, the
+	 * state machine is allocated when the BSC
+	 * is registerd. */
+	struct a_reset_ctx *reset;
+
+	/* A pointer to the sccp_user that is associated
+	 * with the A interface. We need this information
+	 * to send the resets and to send paging requests */
+	struct osmo_sccp_user *sccp_user;
+};
+
+/* Initalize A interface connection between to MSC and BSC */
+int a_init(struct osmo_sccp_instance *sccp, struct gsm_network *network);
+
+/* Send DTAP message via A-interface */
+int a_iface_tx_dtap(struct msgb *msg);
+
+/* Send Cipher mode command via A-interface */
+int a_iface_tx_cipher_mode(const struct gsm_subscriber_connection *conn,
+			   int cipher, const const uint8_t *key, int len, int include_imeisv);
+
+/* Page a subscriber via A-interface */
+int a_iface_tx_paging(const char *imsi, uint32_t tmsi, uint16_t lac);
+
+/* Send assignment request via A-interface */
+int a_iface_tx_assignment(const struct gsm_trans *trans);
+
+/* Send clear command via A-interface */
+int a_iface_tx_clear_cmd(struct gsm_subscriber_connection *conn);
+
+/* Clear all subscriber connections on a specified BSC
+ * (Helper function for a_iface_bssap.c) */
+void a_clear_all(struct osmo_sccp_user *scu, const struct osmo_sccp_addr *bsc_addr);
+
+/* Delete info of a closed connection from the active connection list
+ * (Helper function for a_iface_bssap.c) */
+void a_delete_bsc_con(uint32_t conn_id);