1 files changed, 381 insertions, 0 deletions
diff --git a/src/osmo-bsc/osmo_bsc_filter.c b/src/osmo-bsc/osmo_bsc_filter.c
new file mode 100644
index 000000000..2c84b169f
--- /dev/null
+++ b/src/osmo-bsc/osmo_bsc_filter.c
@@ -0,0 +1,381 @@
+/* (C) 2009-2011 by Holger Hans Peter Freyther <zecke@selfish.org>
+ * (C) 2009-2011 by On-Waves
+ * 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 <openbsc/osmo_bsc.h>
+#include <openbsc/bsc_msc_data.h>
+#include <openbsc/gsm_04_80.h>
+#include <openbsc/gsm_subscriber.h>
+#include <openbsc/bsc_subscriber.h>
+#include <openbsc/debug.h>
+#include <openbsc/paging.h>
+
+#include <stdlib.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;
+	}
+}
+
+/* extract a subscriber from the paging response */
+static struct bsc_subscr *extract_sub(struct gsm_subscriber_connection *conn,
+				   struct msgb *msg)
+{
+	uint8_t mi_type;
+	char mi_string[GSM48_MI_SIZE];
+	struct gsm48_hdr *gh;
+	struct gsm48_pag_resp *resp;
+	struct bsc_subscr *subscr;
+
+	if (msgb_l3len(msg) < sizeof(*gh) + sizeof(*resp)) {
+		LOGP(DMSC, LOGL_ERROR, "PagingResponse too small: %u\n", msgb_l3len(msg));
+		return NULL;
+	}
+
+	gh = msgb_l3(msg);
+	resp = (struct gsm48_pag_resp *) &gh->data[0];
+
+	gsm48_paging_extract_mi(resp, msgb_l3len(msg) - sizeof(*gh),
+				mi_string, &mi_type);
+	DEBUGP(DRR, "PAGING RESPONSE: MI(%s)=%s\n",
+		gsm48_mi_type_name(mi_type), mi_string);
+
+	switch (mi_type) {
+	case GSM_MI_TYPE_TMSI:
+		subscr = bsc_subscr_find_by_tmsi(conn->network->bsc_subscribers,
+					      tmsi_from_string(mi_string));
+		break;
+	case GSM_MI_TYPE_IMSI:
+		subscr = bsc_subscr_find_by_imsi(conn->network->bsc_subscribers,
+					      mi_string);
+		break;
+	default:
+		subscr = NULL;
+		break;
+	}
+
+	return subscr;
+}
+
+/* we will need to stop the paging request */
+static int handle_page_resp(struct gsm_subscriber_connection *conn, struct msgb *msg)
+{
+	struct bsc_subscr *subscr = extract_sub(conn, msg);
+
+	if (!subscr) {
+		LOGP(DMSC, LOGL_ERROR, "Non active subscriber got paged.\n");
+		return -1;
+	}
+
+	paging_request_stop(&conn->network->bts_list, conn->bts, subscr, conn,
+			    msg);
+	bsc_subscr_put(subscr);
+	return 0;
+}
+
+static int is_cm_service_for_emerg(struct msgb *msg)
+{
+	struct gsm48_service_request *cm;
+	struct gsm48_hdr *gh = msgb_l3(msg);
+
+	if (msgb_l3len(msg) < sizeof(*gh) + sizeof(*cm)) {
+		LOGP(DMSC, LOGL_ERROR, "CM ServiceRequest does not fit.\n");
+		return 0;
+	}
+
+	cm = (struct gsm48_service_request *) &gh->data[0];
+	return cm->cm_service_type == GSM48_CMSERV_EMERGENCY;
+}
+
+struct bsc_msc_data *bsc_find_msc(struct gsm_subscriber_connection *conn,
+				   struct msgb *msg)
+{
+	struct gsm48_hdr *gh;
+	int8_t pdisc;
+	uint8_t mtype;
+	struct osmo_bsc_data *bsc;
+	struct bsc_msc_data *msc, *pag_msc;
+	struct bsc_subscr *subscr;
+	int is_emerg = 0;
+
+	bsc = conn->bts->network->bsc_data;
+
+	if (msgb_l3len(msg) < sizeof(*gh)) {
+		LOGP(DMSC, LOGL_ERROR, "There is no GSM48 header here.\n");
+		return NULL;
+	}
+
+	gh = msgb_l3(msg);
+	pdisc = gsm48_hdr_pdisc(gh);
+	mtype = gsm48_hdr_msg_type(gh);
+
+	/*
+	 * We are asked to select a MSC here but they are not equal. We
+	 * want to respond to a paging request on the MSC where we got the
+	 * request from. This is where we need to decide where this connection
+	 * will go.
+	 */
+	if (pdisc == GSM48_PDISC_RR && mtype == GSM48_MT_RR_PAG_RESP)
+		goto paging;
+	else if (pdisc == GSM48_PDISC_MM && mtype == GSM48_MT_MM_CM_SERV_REQ) {
+		is_emerg = is_cm_service_for_emerg(msg);
+		goto round_robin;
+	} else
+		goto round_robin;
+
+round_robin:
+	llist_for_each_entry(msc, &bsc->mscs, entry) {
+		if (!msc->msc_con->is_authenticated)
+			continue;
+		if (!is_emerg && msc->type != MSC_CON_TYPE_NORMAL)
+			continue;
+		if (is_emerg && !msc->allow_emerg)
+			continue;
+
+		/* force round robin by moving it to the end */
+		llist_move_tail(&msc->entry, &bsc->mscs);
+		return msc;
+	}
+
+	return NULL;
+
+paging:
+	subscr = extract_sub(conn, msg);
+
+	if (!subscr) {
+		LOGP(DMSC, LOGL_ERROR, "Got paged but no subscriber found.\n");
+		return NULL;
+	}
+
+	pag_msc = paging_get_data(conn->bts, subscr);
+	bsc_subscr_put(subscr);
+
+	llist_for_each_entry(msc, &bsc->mscs, entry) {
+		if (msc != pag_msc)
+			continue;
+
+		/*
+		 * We don't check if the MSC is connected. In case it
+		 * is not the connection will be dropped.
+		 */
+
+		/* force round robin by moving it to the end */
+		llist_move_tail(&msc->entry, &bsc->mscs);
+		return msc;
+	}
+
+	LOGP(DMSC, LOGL_ERROR, "Got paged but no request found.\n");
+	return NULL;
+}
+
+
+/**
+ * This is used to scan a message for extra functionality of the BSC. This
+ * includes scanning for location updating requests/acceptd and then send
+ * a welcome USSD message to the subscriber.
+ */
+int bsc_scan_bts_msg(struct gsm_subscriber_connection *conn, struct msgb *msg)
+{
+	struct gsm48_hdr *gh = msgb_l3(msg);
+	uint8_t pdisc = gsm48_hdr_pdisc(gh);
+	uint8_t mtype = gsm48_hdr_msg_type(gh);
+
+	if (pdisc == GSM48_PDISC_MM) {
+		if (mtype == GSM48_MT_MM_LOC_UPD_REQUEST)
+			handle_lu_request(conn, msg);
+	} else if (pdisc == GSM48_PDISC_RR) {
+		if (mtype == GSM48_MT_RR_PAG_RESP)
+			handle_page_resp(conn, msg);
+	}
+
+	return 0;
+}
+
+static int send_welcome_ussd(struct gsm_subscriber_connection *conn)
+{
+	struct osmo_bsc_sccp_con *bsc_con;
+
+	bsc_con = conn->sccp_con;
+	if (!bsc_con) {
+		LOGP(DMSC, LOGL_DEBUG, "No SCCP connection associated.\n");
+		return 0;
+	}
+
+	if (!bsc_con->msc->ussd_welcome_txt) {
+		LOGP(DMSC, LOGL_DEBUG, "No USSD Welcome text defined.\n");
+		return 0;
+	}
+
+	return BSS_SEND_USSD;
+}
+
+int bsc_send_welcome_ussd(struct gsm_subscriber_connection *conn)
+{
+	bsc_send_ussd_notify(conn, 1, conn->sccp_con->msc->ussd_welcome_txt);
+	bsc_send_ussd_release_complete(conn);
+
+	return 0;
+}
+
+static int bsc_patch_mm_info(struct gsm_subscriber_connection *conn,
+		uint8_t *data, unsigned int length)
+{
+	struct tlv_parsed tp;
+	int parse_res;
+	struct gsm_bts *bts = conn->bts;
+	int tzunits;
+	uint8_t tzbsd = 0;
+	uint8_t dst = 0;
+
+	parse_res = tlv_parse(&tp, &gsm48_mm_att_tlvdef, data, length, 0, 0);
+	if (parse_res <= 0 && parse_res != -3)
+		/* FIXME: -3 means unknown IE error, so this accepts messages
+		 * with unknown IEs. But parsing has aborted with the unknown
+		 * IE and the message is broken or parsed incompletely. */
+		return 0;
+
+	/* Is TZ patching enabled? */
+	struct gsm_tz *tz = &bts->network->tz;
+	if (!tz->override)
+		return 0;
+
+	/* Convert tz.hr and tz.mn to units */
+	if (tz->hr < 0) {
+		tzunits = -tz->hr*4;
+		tzbsd |= 0x08;
+	} else
+		tzunits = tz->hr*4;
+
+	tzunits = tzunits + (tz->mn/15);
+
+	tzbsd |= (tzunits % 10)*0x10 + (tzunits / 10);
+
+	/* Convert DST value */
+	if (tz->dst >= 0 && tz->dst <= 2)
+		dst = tz->dst;
+
+	if (TLVP_PRESENT(&tp, GSM48_IE_UTC)) {
+		LOGP(DMSC, LOGL_DEBUG,
+			"Changing 'Local time zone' from 0x%02x to 0x%02x.\n",
+			TLVP_VAL(&tp, GSM48_IE_UTC)[6], tzbsd);
+		((uint8_t *)(TLVP_VAL(&tp, GSM48_IE_UTC)))[0] = tzbsd;
+	}
+	if (TLVP_PRESENT(&tp, GSM48_IE_NET_TIME_TZ)) {
+		LOGP(DMSC, LOGL_DEBUG,
+			"Changing 'Universal time and local time zone' TZ from "
+			"0x%02x to 0x%02x.\n",
+			TLVP_VAL(&tp, GSM48_IE_NET_TIME_TZ)[6], tzbsd);
+		((uint8_t *)(TLVP_VAL(&tp, GSM48_IE_NET_TIME_TZ)))[6] = tzbsd;
+	}
+#ifdef GSM48_IE_NET_DST
+	if (TLVP_PRESENT(&tp, GSM48_IE_NET_DST)) {
+		LOGP(DMSC, LOGL_DEBUG,
+			"Changing 'Network daylight saving time' from "
+			"0x%02x to 0x%02x.\n",
+			TLVP_VAL(&tp, GSM48_IE_NET_DST)[0], dst);
+		((uint8_t *)(TLVP_VAL(&tp, GSM48_IE_NET_DST)))[0] = dst;
+	}
+#endif
+
+	return 0;
+}
+
+static int has_core_identity(struct bsc_msc_data *msc)
+{
+	if (msc->core_mnc != -1)
+		return 1;
+	if (msc->core_mcc != -1)
+		return 1;
+	if (msc->core_lac != -1)
+		return 1;
+	if (msc->core_ci != -1)
+		return 1;
+	return 0;
+}
+
+/**
+ * Messages coming back from the MSC.
+ */
+int bsc_scan_msc_msg(struct gsm_subscriber_connection *conn, struct msgb *msg)
+{
+	struct bsc_msc_data *msc;
+	struct gsm_network *net;
+	struct gsm48_loc_area_id *lai;
+	struct gsm48_hdr *gh;
+	uint8_t pdisc;
+	uint8_t mtype;
+	int length = msgb_l3len(msg);
+
+	if (length < sizeof(*gh)) {
+		LOGP(DMSC, LOGL_ERROR, "GSM48 header does not fit.\n");
+		return -1;
+	}
+
+	gh = (struct gsm48_hdr *) msgb_l3(msg);
+	length -= (const char *)&gh->data[0] - (const char *)gh;
+
+	pdisc = gsm48_hdr_pdisc(gh);
+	if (pdisc != GSM48_PDISC_MM)
+		return 0;
+
+	mtype = gsm48_hdr_msg_type(gh);
+	net = conn->bts->network;
+	msc = conn->sccp_con->msc;
+
+	if (mtype == GSM48_MT_MM_LOC_UPD_ACCEPT) {
+		if (has_core_identity(msc)) {
+			if (msgb_l3len(msg) >= sizeof(*gh) + sizeof(*lai)) {
+				/* overwrite LAI in the message */
+				lai = (struct gsm48_loc_area_id *) &gh->data[0];
+				gsm48_generate_lai(lai, net->country_code,
+						   net->network_code,
+						   conn->bts->location_area_code);
+			}
+		}
+
+		if (conn->sccp_con->new_subscriber)
+			return send_welcome_ussd(conn);
+		return 0;
+	} else if (mtype == GSM48_MT_MM_INFO) {
+		bsc_patch_mm_info(conn, &gh->data[0], length);
+	}
+
+	return 0;
+}