Prepare entry/exit point for MSC -> BSC and MSC -> RNC communication.

Add msc_ifaces.[hc], a_iface.c, with a general msc_tx_dtap() to redirect to
different interfaces depending on the actual subscriber connection.

While iu_tx() is going to be functional fairly soon, the a_tx() is going to be
just a dummy for some time (see comment).

Add Iu specific fields in gsm_subscriber_connection: the UE connection pointer
and an indicator for the Integrity Protection status on Iu (to be fully
implemented in later commits).

Add lac member to gsm_subscriber_connection, to allow decoupling from
bts->location_area_code. The conn->lac will actually be set in iu.c in an
upcoming commit ("add iucs.[hc]").

Change-Id: Idf8020a30562426e8f939706bf5c2188d5a09798

3 files changed, 86 insertions, 0 deletions

diff --git a/openbsc/src/libmsc/Makefile.am b/openbsc/src/libmsc/Makefile.am
index 3f4174ca5..7ab30d029 100644
--- a/openbsc/src/libmsc/Makefile.am
+++ b/openbsc/src/libmsc/Makefile.am
@@ -23,6 +23,7 @@ noinst_LIBRARIES = \
 	$(NULL)
 
 libmsc_a_SOURCES = \
+	a_iface.c \
 	auth.c \
 	db.c \
 	gsm_04_08.c \
@@ -32,6 +33,7 @@ libmsc_a_SOURCES = \
 	mncc.c \
 	mncc_builtin.c \
 	mncc_sock.c \
+	msc_ifaces.c \
 	rrlp.c \
 	silent_call.c \
 	sms_queue.c \
diff --git a/openbsc/src/libmsc/a_iface.c b/openbsc/src/libmsc/a_iface.c
new file mode 100644
index 000000000..0eaeef188
--- /dev/null
+++ b/openbsc/src/libmsc/a_iface.c
@@ -0,0 +1,33 @@
+/* A-interface implementation, from MSC to BSC */
+
+/* (C) 2016 by sysmocom s.m.f.c GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * 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/msgb.h>
+#include <osmocom/core/logging.h>
+
+#include <openbsc/msc_ifaces.h>
+#include <openbsc/debug.h>
+
+int a_tx(struct msgb *msg)
+{
+	LOGP(DMSC, LOGL_ERROR, "message to be sent to BSC, but A-interface"
+	     " not implemented.\n%s\n", osmo_hexdump(msg->data, msg->len));
+	return -1;
+}
diff --git a/openbsc/src/libmsc/msc_ifaces.c b/openbsc/src/libmsc/msc_ifaces.c
new file mode 100644
index 000000000..160c90b95
--- /dev/null
+++ b/openbsc/src/libmsc/msc_ifaces.c
@@ -0,0 +1,51 @@
+/* Implementation for MSC decisions which interface to send messages out on. */
+
+/* (C) 2016 by sysmocom s.m.f.c GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * 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/logging.h>
+
+#include <openbsc/debug.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/msc_ifaces.h>
+
+static int msc_tx(struct gsm_subscriber_connection *conn, struct msgb *msg)
+{
+	switch (conn->via_ran) {
+	case RAN_GERAN_A:
+		msg->dst = conn;
+		return a_tx(msg);
+
+	case RAN_UTRAN_IU:
+		msg->dst = conn->iu.ue_ctx;
+		return iu_tx(msg, 0);
+
+	default:
+		LOGP(DMSC, LOGL_ERROR,
+		     "msc_tx(): conn->via_ran invalid (%d)\n",
+		     conn->via_ran);
+		return -1;
+	}
+}
+
+
+int msc_tx_dtap(struct gsm_subscriber_connection *conn,
+		struct msgb *msg)
+{
+	return msc_tx(conn, msg);
+}