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-rw-r--r--src/libmsc/silent_call.c143
1 files changed, 143 insertions, 0 deletions
diff --git a/src/libmsc/silent_call.c b/src/libmsc/silent_call.c
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+++ b/src/libmsc/silent_call.c
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+/* GSM silent call feature */
+
+/*
+ * (C) 2009 by Harald Welte <laforge@gnumonks.org>
+ *
+ * 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 <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <osmocore/msgb.h>
+#include <openbsc/signal.h>
+#include <openbsc/debug.h>
+#include <openbsc/paging.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/gsm_subscriber.h>
+#include <openbsc/abis_rsl.h>
+#include <openbsc/chan_alloc.h>
+#include <openbsc/osmo_msc.h>
+
+/* paging of the requested subscriber has completed */
+static int paging_cb_silent(unsigned int hooknum, unsigned int event,
+ struct msgb *msg, void *_conn, void *_data)
+{
+ struct gsm_subscriber_connection *conn = _conn;
+ struct scall_signal_data sigdata;
+ int rc = 0;
+
+ if (hooknum != GSM_HOOK_RR_PAGING)
+ return -EINVAL;
+
+ DEBUGP(DSMS, "paging_cb_silent: ");
+
+ sigdata.conn = conn;
+ sigdata.data = _data;
+
+ switch (event) {
+ case GSM_PAGING_SUCCEEDED:
+ DEBUGPC(DSMS, "success, using Timeslot %u on ARFCN %u\n",
+ conn->lchan->ts->nr, conn->lchan->ts->trx->arfcn);
+ conn->silent_call = 1;
+ /* increment lchan reference count */
+ dispatch_signal(SS_SCALL, S_SCALL_SUCCESS, &sigdata);
+ break;
+ case GSM_PAGING_EXPIRED:
+ case GSM_PAGING_BUSY:
+ case GSM_PAGING_OOM:
+ DEBUGP(DSMS, "expired\n");
+ dispatch_signal(SS_SCALL, S_SCALL_EXPIRED, &sigdata);
+ break;
+ default:
+ rc = -EINVAL;
+ break;
+ }
+
+ return rc;
+}
+
+/* receive a layer 3 message from a silent call */
+int silent_call_rx(struct gsm_subscriber_connection *conn, struct msgb *msg)
+{
+ /* FIXME: do something like sending it through a UDP port */
+ return 0;
+}
+
+struct msg_match {
+ u_int8_t pdisc;
+ u_int8_t msg_type;
+};
+
+/* list of messages that are handled inside OpenBSC, even in a silent call */
+static const struct msg_match silent_call_accept[] = {
+ { GSM48_PDISC_MM, GSM48_MT_MM_LOC_UPD_REQUEST },
+ { GSM48_PDISC_MM, GSM48_MT_MM_CM_SERV_REQ },
+};
+
+/* decide if we need to reroute a message as part of a silent call */
+int silent_call_reroute(struct gsm_subscriber_connection *conn, struct msgb *msg)
+{
+ struct gsm48_hdr *gh = msgb_l3(msg);
+ u_int8_t pdisc = gh->proto_discr & 0x0f;
+ int i;
+
+ /* if we're not part of a silent call, never reroute */
+ if (!conn->silent_call)
+ return 0;
+
+ /* check if we are a special message that is handled in openbsc */
+ for (i = 0; i < ARRAY_SIZE(silent_call_accept); i++) {
+ if (silent_call_accept[i].pdisc == pdisc &&
+ silent_call_accept[i].msg_type == gh->msg_type)
+ return 0;
+ }
+
+ /* otherwise, reroute */
+ return 1;
+}
+
+
+/* initiate a silent call with a given subscriber */
+int gsm_silent_call_start(struct gsm_subscriber *subscr, void *data, int type)
+{
+ int rc;
+
+ rc = paging_request(subscr->net, subscr, type,
+ paging_cb_silent, data);
+ return rc;
+}
+
+/* end a silent call with a given subscriber */
+int gsm_silent_call_stop(struct gsm_subscriber *subscr)
+{
+ struct gsm_subscriber_connection *conn;
+
+ conn = connection_for_subscr(subscr);
+ if (!conn)
+ return -EINVAL;
+
+ /* did we actually establish a silent call for this guy? */
+ if (!conn->silent_call)
+ return -EINVAL;
+
+ conn->silent_call = 0;
+ msc_release_connection(conn);
+
+ return 0;
+}