1 files changed, 340 insertions, 0 deletions
diff --git a/openbsc/src/osmo-bsc/osmo_bsc_sigtran.c b/openbsc/src/osmo-bsc/osmo_bsc_sigtran.c
new file mode 100644
index 000000000..b95ec9ddc
--- /dev/null
+++ b/openbsc/src/osmo-bsc/osmo_bsc_sigtran.c
@@ -0,0 +1,340 @@
+/* (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/>.
+ *
+ */
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/logging.h>
+#include <osmocom/sigtran/osmo_ss7.h>
+#include <osmocom/sigtran/sccp_sap.h>
+#include <osmocom/sccp/sccp_types.h>
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/gsm/gsm0808.h>
+#include <osmocom/core/msgb.h>
+#include <openbsc/bsc_msc_data.h>
+#include <openbsc/debug.h>
+#include <openbsc/osmo_bsc.h>
+#include <openbsc/osmo_bsc_grace.h>
+#include <openbsc/osmo_bsc_sigtran.h>
+
+/* A pointer to a list with all involved MSCs
+ * (a copy of the pointer location submitted with osmo_bsc_sigtran_init() */
+static struct llist_head *msc_list;
+
+#define RESET_INTERVAL 1	/* sek */
+#define SCCP_MSG_MAXSIZE 1024
+
+static LLIST_HEAD(active_connections);
+
+/* Helper function to Check if the given connection id is already assigned */
+static struct osmo_bsc_sccp_con *get_bsc_conn_by_conn_id(int conn_id)
+{
+	conn_id &= 0xFFFFFF;
+	struct osmo_bsc_sccp_con *bsc_con;
+
+	llist_for_each_entry(bsc_con, &active_connections, entry) {
+		if (bsc_con->conn_id == conn_id)
+			return bsc_con;
+	}
+
+	return NULL;
+}
+
+/* Pick a free connection id */
+static int pick_free_conn_id(struct bsc_msc_data *msc)
+{
+	int conn_id = msc->msc_con->conn_id_counter;
+	int i;
+
+	for (i = 0; i < 0xFFFFFF; i++) {
+		conn_id++;
+		conn_id &= 0xFFFFFF;
+		if (get_bsc_conn_by_conn_id(conn_id) == false) {
+			msc->msc_con->conn_id_counter = conn_id;
+			return conn_id;
+		}
+	}
+
+	return -1;
+}
+
+/* Timer callback to handle the MSC reset procedure */
+static void msc_reset_timer_cb(void *data)
+{
+	/* FIXME: Probably the reset procedure should be moved to osmo_bsc_bssap.c,
+	 * since it is clearly in the BSSAP's area of accountability */
+	struct bsc_msc_data *msc = (struct bsc_msc_data *)data;
+	struct msgb *msg = NULL;
+
+	/* Stop sending RESET messages as soon as the
+	 * connection is marked as connected. */
+	if (msc->msc_con->reset_ack)
+		return;
+
+	LOGP(DMSC, LOGL_NOTICE, "Sending RESET to MSC No.: %i\n", msc->nr);
+
+	msg = gsm0808_create_reset();
+	osmo_sccp_tx_unitdata_msg(msc->msc_con->sccp_user, &msc->msc_con->g_calling_addr,
+				  &msc->msc_con->g_called_addr, msg);
+
+	osmo_timer_schedule(&msc->msc_con->msc_reset_timer, RESET_INTERVAL, 0);
+}
+
+/* Perform MSC reset procedure */
+static void msc_reset(struct bsc_msc_data *msc)
+{
+	LOGP(DMSC, LOGL_NOTICE, "Starting RESET for MSC No.: %i\n", msc->nr);
+	msc->msc_con->msc_reset_timer.cb = msc_reset_timer_cb;
+	msc->msc_con->msc_reset_timer.data = msc;
+	msc->msc_con->reset_ack = false;
+	osmo_timer_schedule(&msc->msc_con->msc_reset_timer, RESET_INTERVAL, 0);
+}
+
+/* Find an MSC by its sigtran point code */
+static struct bsc_msc_data *get_msc_by_addr(struct osmo_sccp_addr *calling_addr)
+{
+	struct bsc_msc_data *msc;
+	llist_for_each_entry(msc, msc_list, entry) {
+		if (memcmp(calling_addr, &msc->msc_con->g_called_addr, sizeof(*calling_addr)) == 0)
+			return msc;
+	}
+
+	LOGP(DMSC, LOGL_ERROR, "Unable to find MSC data under address: %s\n", osmo_sccp_addr_dump(calling_addr));
+	return NULL;
+}
+
+/* Send data to MSC, use the connection id which MSC it is */
+static int handle_data_from_msc(int conn_id, struct msgb *msg)
+{
+	struct osmo_bsc_sccp_con *bsc_con = get_bsc_conn_by_conn_id(conn_id);
+	int rc = -EINVAL;
+
+	if (bsc_con) {
+		msg->l3h = msgb_l2(msg);
+		rc = bsc_handle_dt1(bsc_con, msg, msgb_l2len(msg));
+	} else
+		LOGP(DMSC, LOGL_NOTICE, "incoming data from unknown connection id: %i\n", conn_id);
+
+	return rc;
+}
+
+/* Sent unitdata to MSC, use the point code to determine which MSC it is */
+static int handle_unitdata_from_msc(struct osmo_sccp_addr *calling_addr, struct msgb *msg)
+{
+	struct bsc_msc_data *msc = get_msc_by_addr(calling_addr);
+	int rc = -EINVAL;
+
+	if (msc) {
+		msg->l3h = msgb_l2(msg);
+		rc = bsc_handle_udt(msc, msg, msgb_l2len(msg));
+	} else
+		LOGP(DMSC, LOGL_NOTICE, "incoming unitdata data from unknown remote address: %s\n",
+		     osmo_sccp_addr_dump(calling_addr));
+
+	return rc;
+}
+
+/* Callback function, called by the SSCP stack when data arrives */
+static int sccp_sap_up(struct osmo_prim_hdr *oph, void *_scu)
+{
+	struct osmo_scu_prim *scu_prim = (struct osmo_scu_prim *)oph;
+	struct osmo_sccp_user *scu = _scu;
+	int rc = 0;
+
+	switch (OSMO_PRIM_HDR(&scu_prim->oph)) {
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_UNITDATA, PRIM_OP_INDICATION):
+		/* Handle inbound UNITDATA */
+		DEBUGP(DMSC, "N-UNITDATA.ind(%s)\n", osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
+		rc = handle_unitdata_from_msc(&scu_prim->u.unitdata.calling_addr, oph->msg);
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_CONNECT, PRIM_OP_INDICATION):
+		/* Handle (Reject) inbound connections */
+		DEBUGP(DMSC, "N-CONNECT.ind(X->%u)\n", scu_prim->u.connect.conn_id);
+		LOGP(DMSC, LOGL_DEBUG, "Rejecting inbound SCCP connection...\n");
+		rc = osmo_sccp_tx_disconn(scu, scu_prim->u.connect.conn_id, &scu_prim->u.connect.called_addr, 0);
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_CONNECT, PRIM_OP_CONFIRM):
+		/* Handle outbound connection confirmation */
+		if (msgb_l2len(oph->msg) > 0) {
+			DEBUGP(DMSC, "N-CONNECT.cnf(%u, %s)\n", scu_prim->u.connect.conn_id,
+			       osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
+			rc = handle_data_from_msc(scu_prim->u.connect.conn_id, oph->msg);
+		} else
+			DEBUGP(DRANAP, "N-CONNECT.cnf(%u)\n", scu_prim->u.connect.conn_id);
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_DATA, PRIM_OP_INDICATION):
+		/* Handle incoming connection oriented data */
+		DEBUGP(DMSC, "N-DATA.ind(%u, %s)\n", scu_prim->u.data.conn_id,
+		       osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
+		rc = handle_data_from_msc(scu_prim->u.data.conn_id, oph->msg);
+		break;
+
+	case OSMO_PRIM(OSMO_SCU_PRIM_N_DISCONNECT, PRIM_OP_INDICATION):
+		/* indication of disconnect */
+		if (msgb_l2len(oph->msg) > 0) {
+			DEBUGP(DMSC, "N-DISCONNECT.ind(%u, %s)\n", scu_prim->u.disconnect.conn_id,
+			       osmo_hexdump(msgb_l2(oph->msg), msgb_l2len(oph->msg)));
+			handle_data_from_msc(scu_prim->u.disconnect.conn_id, oph->msg);
+		} else
+			DEBUGP(DRANAP, "N-DISCONNECT.ind(%u)\n", scu_prim->u.disconnect.conn_id);
+
+		rc = osmo_bsc_sigtran_del_conn(get_bsc_conn_by_conn_id(scu_prim->u.disconnect.conn_id));
+		break;
+
+	default:
+		LOGP(DMSC, LOGL_ERROR, "Unhandled SIGTRAN primitive: %u:%u\n", oph->primitive, oph->operation);
+		break;
+	}
+
+	msgb_free(oph->msg);
+	return rc;
+}
+
+/* Allocate resources to make a new connection oriented sigtran connection
+ * (not the connection ittself!) */
+enum bsc_con osmo_bsc_sigtran_new_conn(struct gsm_subscriber_connection *conn, struct bsc_msc_data *msc)
+{
+	struct osmo_bsc_sccp_con *bsc_con;
+	int conn_id;
+
+	OSMO_ASSERT(conn);
+	OSMO_ASSERT(msc);
+
+	LOGP(DMSC, LOGL_NOTICE, "Initalizing resources for new SIGTRAN connection to MSC No.: %i...\n", msc->nr);
+
+	/* This should not trigger */
+	if (!msc || !msc->msc_con->is_authenticated) {
+		LOGP(DMSC, LOGL_ERROR, "How did this happen? MSC is not connected. Dropping.\n");
+		return BSC_CON_REJECT_NO_LINK;
+	}
+
+	if (!bsc_grace_allow_new_connection(conn->bts->network, conn->bts)) {
+		LOGP(DMSC, LOGL_NOTICE, "BSC in grace period. No new connections.\n");
+		return BSC_CON_REJECT_RF_GRACE;
+	}
+
+	bsc_con = talloc_zero(conn->bts, struct osmo_bsc_sccp_con);
+	if (!bsc_con) {
+		LOGP(DMSC, LOGL_ERROR, "Failed to allocate new SIGTRAN connection.\n");
+		return BSC_CON_NO_MEM;
+	}
+
+	bsc_con->msc = msc;
+	bsc_con->conn = conn;
+	llist_add_tail(&bsc_con->entry, &active_connections);
+	conn->sccp_con = bsc_con;
+
+	/* Pick a free connection id */
+	conn_id = pick_free_conn_id(msc);
+	if (conn_id < 0)
+		return BSC_CON_REJECT_NO_LINK;
+	bsc_con->conn_id = conn_id;
+
+	LOGP(DMSC, LOGL_NOTICE, "Allocated new connection id: %i\n", conn_id);
+
+	return BSC_CON_SUCCESS;
+}
+
+/* Open a new connection oriented sigtran connection */
+int osmo_bsc_sigtran_open_conn(struct osmo_bsc_sccp_con *conn, struct msgb *msg)
+{
+	struct bsc_msc_data *msc = conn->msc;
+	int conn_id = conn->conn_id;
+	int rc;
+
+	OSMO_ASSERT(conn);
+	OSMO_ASSERT(msg);
+
+	LOGP(DMSC, LOGL_NOTICE, "Opening new SIGTRAN connection (id=%i) to MSC No.: %i...\n", conn_id, msc->nr);
+
+	rc = osmo_sccp_tx_conn_req_msg(msc->msc_con->sccp_user, conn_id, &msc->msc_con->g_calling_addr,
+				       &msc->msc_con->g_called_addr, msg);
+
+	return rc;
+}
+
+/* Send data to MSC */
+int osmo_bsc_sigtran_send(struct osmo_bsc_sccp_con *conn, struct msgb *msg)
+{
+	int conn_id;
+	int rc;
+	struct bsc_msc_data *msc;
+
+	OSMO_ASSERT(conn);
+	OSMO_ASSERT(msg);
+
+	msc = conn->msc;
+	conn_id = conn->conn_id;
+
+	LOGP(DMSC, LOGL_DEBUG, "Sending connection (id=%i) oriented data to MSC No.: %i...\n", conn_id, msc->nr);
+	rc = osmo_sccp_tx_data_msg(msc->msc_con->sccp_user, conn_id, msg);
+
+	return rc;
+}
+
+/* Delete a connection from the list with open connections
+ * (called by osmo_bsc_api.c on failing open connections and
+ * locally, when a connection is closed by the MSC */
+int osmo_bsc_sigtran_del_conn(struct osmo_bsc_sccp_con *sccp)
+{
+	if (!sccp)
+		return 0;
+
+	if (sccp->conn)
+		LOGP(DMSC, LOGL_ERROR, "sccp connection not cleared -- forcefully clearing it now!\n");
+
+	llist_del(&sccp->entry);
+	talloc_free(sccp);
+
+	return 0;
+}
+
+/* Initalize osmo sigtran backhaul */
+int osmo_bsc_sigtran_init(struct llist_head *mscs)
+{
+	/* FIXME: Remove hardcoded IP-Addresses */
+	/* FIXME: Use STP! */
+	struct bsc_msc_data *msc;
+	char msc_name[256];
+
+	OSMO_ASSERT(mscs);
+
+	osmo_ss7_init();
+
+	msc_list = mscs;
+
+	llist_for_each_entry(msc, msc_list, entry) {
+		snprintf(msc_name, sizeof(msc_name), "MSC No.: %u", msc->nr);
+		LOGP(DMSC, LOGL_NOTICE, "Initalizing SCCP connection to %s\n", msc_name);
+
+		/* SCCP Protocol stack */
+		msc->msc_con->sccp =
+		    osmo_sccp_simple_client(NULL, msc_name, msc->msc_con->g_calling_addr.pc,
+					    OSMO_SS7_ASP_PROT_M3UA, 0, NULL, M3UA_PORT, "127.0.0.2");
+		msc->msc_con->sccp_user =
+		    osmo_sccp_user_bind(msc->msc_con->sccp, msc_name, sccp_sap_up, SCCP_SSN_BSSAP);
+
+		/* Start MSC reset procedure */
+		msc_reset(msc);
+	}
+
+	return 0;
+}