1 files changed, 93 insertions, 0 deletions
diff --git a/openbsc/src/osmo-cscn/iu_cs.c b/openbsc/src/osmo-cscn/iu_cs.c
new file mode 100644
index 000000000..c8a36f47b
--- /dev/null
+++ b/openbsc/src/osmo-cscn/iu_cs.c
@@ -0,0 +1,93 @@
+#include <openbsc/gsm_data.h>
+#include <openbsc/iu.h>
+
+/* Return an existing Iu-CS subscriber connection record for the given link and
+ * connection IDs, or return NULL if not found. */
+static struct gsm_subscriber_connection *subscr_conn_lookup_iu(struct gsm_network *network,
+							       uint8_t link_id,
+							       uint32_t conn_id)
+{
+	struct gsm_subscriber_connection *conn;
+	llist_for_each_entry(conn, &network->subscr_conns, entry) {
+		if (conn->via_iface != IFACE_IUCS)
+			continue;
+		if (conn->iu.link_id != link_id)
+			continue;
+		if (conn->iu.conn_id != conn_id)
+			continue;
+		return conn;
+	}
+	return NULL;
+}
+
+/* Receive MM/CC/... message from Iu-CS (SCCP user SAP).
+ * msg->dst must reference a struct ue_conn_ctx. link_id identifies the SCTP
+ * peer that sent the msg.
+ *
+ * For A-interface see libbsc/bsc_api.c gsm0408_rcvmsg(). */
+int gsm0408_rcvmsg_iucs(struct gsm_network *network, struct msgb *msg, uint8_t link_id)
+{
+	int rc;
+	struct ue_conn_ctx *ue_ctx;
+	struct gsm_subscriber_connection *conn;
+
+	ue_ctx = (struct ue_conn_ctx*)msg->dst;
+
+	/* TODO: are there message types that could allow us to skip this
+	 * search? */
+	conn = subscr_conn_lookup_iu(network, link_id, ue_ctx->conn_id);
+
+	if (conn) {
+		/* if we already have a connection, handle DTAP.
+		   gsm0408_dispatch() is aka msc_dtap() */
+
+		/* Make sure we don't receive RR over Iu-CS; otherwise all
+		 * messages handled by gsm0408_dispatch() are of interest (CC,
+		 * MM, SMS, NS_SS, maybe even MM_GPRS and SM_GPRS). */
+		struct gsm48_hdr *gh = msgb_l3(msg);
+		uint8_t pdisc = gh->proto_discr & 0x0f;
+		OSMO_ASSERT(pdisc != GSM48_PDISC_RR);
+
+		gsm0408_dispatch(conn, msg);
+	} else {
+		/* allocate a new connection */
+
+		/* TODO */
+
+#if 0
+		rc = BSC_API_CONN_POL_REJECT;
+		conn = subscr_conn_allocate_iu(msg->lchan);
+		if (!lchan->conn) {
+			lchan_release(lchan, 1, RSL_REL_NORMAL);
+			return -1;
+		}
+
+		/* fwd via bsc_api to send COMPLETE L3 INFO to MSC */
+		rc = api->compl_l3(lchan->conn, msg, 0);
+
+		if (rc != BSC_API_CONN_POL_ACCEPT) {
+			lchan->conn->lchan = NULL;
+			subscr_con_free(lchan->conn);
+			lchan_release(lchan, 1, RSL_REL_NORMAL);
+		}
+#endif
+	}
+
+	return 0;
+}
+
+/* For A-interface see libbsc/bsc_api.c subscr_con_allocate() */
+struct gsm_subscriber_connection *subscr_conn_allocate_iu(struct gsm_bts *bts)
+	/* TODO "bts"? this is an hNodeB, really. */
+{
+	struct gsm_subscriber_connection *conn;
+
+	conn = talloc_zero(bts->network, struct gsm_subscriber_connection);
+	if (!conn)
+		return NULL;
+
+	conn->via_iface = IFACE_IUCS;
+	conn->bts = bts;
+	llist_add_tail(&conn->entry, &bts->network->subscr_conns);
+	return conn;
+}