bsc: Look for location updating requests in messages

Introduce the SCCP connection data and remember that
we were seeing a location updating request from a
different LAC.

2 files changed, 41 insertions, 0 deletions

diff --git a/openbsc/include/openbsc/osmo_bsc.h b/openbsc/include/openbsc/osmo_bsc.h
index 43182ad3e..30e643919 100644
--- a/openbsc/include/openbsc/osmo_bsc.h
+++ b/openbsc/include/openbsc/osmo_bsc.h
@@ -5,6 +5,10 @@
 
 #include "bsc_api.h"
 
+struct osmo_bsc_sccp_con {
+	uint8_t new_subscriber;
+};
+
 struct bsc_api *osmo_bsc_api();
 
 int bsc_queue_for_msc(struct gsm_subscriber_connection *conn, struct msgb *msg);
diff --git a/openbsc/src/bsc/osmo_bsc_filter.c b/openbsc/src/bsc/osmo_bsc_filter.c
index 1aeaa951e..7052cfea1 100644
--- a/openbsc/src/bsc/osmo_bsc_filter.c
+++ b/openbsc/src/bsc/osmo_bsc_filter.c
@@ -19,6 +19,34 @@
  */
 
 #include <openbsc/osmo_bsc.h>
+#include <openbsc/debug.h>
+
+static void handle_lu_request(struct gsm_subscriber_connection *conn,
+			      struct msgb *msg)
+{
+	struct gsm48_hdr *gh;
+	struct gsm48_loc_upd_req *lu;
+	struct gsm48_loc_area_id lai;
+	struct gsm_network *net;
+
+	if (msgb_l3len(msg) < sizeof(*gh) + sizeof(*lu)) {
+		LOGP(DMSC, LOGL_ERROR, "LU too small to look at: %u\n", msgb_l3len(msg));
+		return;
+	}
+
+	net = conn->bts->network;
+
+	gh = msgb_l3(msg);
+	lu = (struct gsm48_loc_upd_req *) gh->data;
+
+	gsm48_generate_lai(&lai, net->country_code, net->network_code,
+			   conn->bts->location_area_code);
+
+	if (memcmp(&lai, &lu->lai, sizeof(lai)) != 0) {
+		LOGP(DMSC, LOGL_DEBUG, "Marking con for welcome USSD.\n");
+		conn->sccp_con->new_subscriber = 1;
+	}
+}
 
 /**
  * This is used to scan a message for extra functionality of the BSC. This
@@ -27,5 +55,14 @@
  */
 int bsc_scan_bts_msg(struct gsm_subscriber_connection *conn, struct msgb *msg)
 {
+	struct gsm48_hdr *gh = msgb_l3(msg);
+	uint8_t pdisc = gh->proto_discr & 0x0f;
+	uint8_t mtype = gh->msg_type & 0xbf;
+
+	if (pdisc == GSM48_PDISC_MM) {
+		if (mtype == GSM48_MT_MM_LOC_UPD_REQUEST)
+			handle_lu_request(conn, msg);
+	}
+
 	return 0;
 }