1 files changed, 395 insertions, 0 deletions
diff --git a/src/libbsc/paging.c b/src/libbsc/paging.c
new file mode 100644
index 000000000..650254575
--- /dev/null
+++ b/src/libbsc/paging.c
@@ -0,0 +1,395 @@
+/* Paging helper and manager.... */
+/* (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.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/>.
+ *
+ */
+
+/*
+ * Relevant specs:
+ *     12.21:
+ *       - 9.4.12 for CCCH Local Threshold
+ *
+ *     05.58:
+ *       - 8.5.2 CCCH Load indication
+ *       - 9.3.15 Paging Load
+ *
+ * Approach:
+ *       - Send paging command to subscriber
+ *       - On Channel Request we will remember the reason
+ *       - After the ACK we will request the identity
+ *	 - Then we will send assign the gsm_subscriber and
+ *	 - and call a callback
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+
+#include <openbsc/paging.h>
+#include <osmocore/talloc.h>
+#include <openbsc/debug.h>
+#include <openbsc/signal.h>
+#include <openbsc/abis_rsl.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/chan_alloc.h>
+#include <openbsc/bsc_api.h>
+
+void *tall_paging_ctx;
+
+#define PAGING_TIMER 0, 500000
+
+static unsigned int calculate_group(struct gsm_bts *bts, struct gsm_subscriber *subscr)
+{
+	int ccch_conf;
+	int bs_cc_chans;
+	int blocks;
+	unsigned int group;
+	
+	ccch_conf = bts->si_common.chan_desc.ccch_conf;
+	bs_cc_chans = rsl_ccch_conf_to_bs_cc_chans(ccch_conf);
+	/* code word + 2, as 2 channels equals 0x0 */
+	blocks = rsl_number_of_paging_subchannels(bts);
+	group = get_paging_group(str_to_imsi(subscr->imsi),
+					bs_cc_chans, blocks);
+	return group;
+}
+
+/*
+ * Kill one paging request update the internal list...
+ */
+static void paging_remove_request(struct gsm_bts_paging_state *paging_bts,
+				struct gsm_paging_request *to_be_deleted)
+{
+	bsc_del_timer(&to_be_deleted->T3113);
+	llist_del(&to_be_deleted->entry);
+	subscr_put(to_be_deleted->subscr);
+	talloc_free(to_be_deleted);
+}
+
+static void page_ms(struct gsm_paging_request *request)
+{
+	u_int8_t mi[128];
+	unsigned int mi_len;
+	unsigned int page_group;
+
+	LOGP(DPAG, LOGL_INFO, "Going to send paging commands: imsi: '%s' tmsi: '0x%x'\n",
+		request->subscr->imsi, request->subscr->tmsi);
+
+	if (request->subscr->tmsi == GSM_RESERVED_TMSI)
+		mi_len = gsm48_generate_mid_from_imsi(mi, request->subscr->imsi);
+	else
+		mi_len = gsm48_generate_mid_from_tmsi(mi, request->subscr->tmsi);
+
+	page_group = calculate_group(request->bts, request->subscr);
+	gsm0808_page(request->bts, page_group, mi_len, mi, request->chan_type);
+}
+
+static void paging_schedule_if_needed(struct gsm_bts_paging_state *paging_bts)
+{
+	if (llist_empty(&paging_bts->pending_requests))
+		return;
+
+	if (!bsc_timer_pending(&paging_bts->work_timer))
+		bsc_schedule_timer(&paging_bts->work_timer, PAGING_TIMER);
+}
+
+
+static void paging_handle_pending_requests(struct gsm_bts_paging_state *paging_bts);
+static void paging_give_credit(void *data)
+{
+	struct gsm_bts_paging_state *paging_bts = data;
+
+	LOGP(DPAG, LOGL_NOTICE, "No slots available on bts nr %d\n", paging_bts->bts->nr);
+	paging_bts->available_slots = 20;
+	paging_handle_pending_requests(paging_bts);
+}
+
+static int can_send_pag_req(struct gsm_bts *bts, int rsl_type)
+{
+	struct pchan_load pl;
+	int count;
+
+	memset(&pl, 0, sizeof(pl));
+	bts_chan_load(&pl, bts);
+
+	switch (rsl_type) {
+	case RSL_CHANNEED_TCH_F:
+	case RSL_CHANNEED_TCH_ForH:
+		goto count_tch;
+		break;
+	case RSL_CHANNEED_SDCCH:
+		goto count_sdcch;
+		break;
+	case RSL_CHANNEED_ANY:
+	default:
+		if (bts->network->pag_any_tch)
+			goto count_tch;
+		else
+			goto count_sdcch;
+		break;
+	}
+
+	return 0;
+
+	/* could available SDCCH */
+count_sdcch:
+	count = 0;
+	count += pl.pchan[GSM_PCHAN_SDCCH8_SACCH8C].total
+			- pl.pchan[GSM_PCHAN_SDCCH8_SACCH8C].used;
+	count += pl.pchan[GSM_PCHAN_CCCH_SDCCH4].total
+			- pl.pchan[GSM_PCHAN_CCCH_SDCCH4].used;
+	return bts->paging.free_chans_need > count;
+
+count_tch:
+	count = 0;
+	count += pl.pchan[GSM_PCHAN_TCH_F].total
+			- pl.pchan[GSM_PCHAN_TCH_F].used;
+	if (bts->network->neci)
+		count += pl.pchan[GSM_PCHAN_TCH_H].total
+				- pl.pchan[GSM_PCHAN_TCH_H].used;
+	return bts->paging.free_chans_need > count;
+}
+
+/*
+ * This is kicked by the periodic PAGING LOAD Indicator
+ * coming from abis_rsl.c
+ *
+ * We attempt to iterate once over the list of items but
+ * only upto available_slots.
+ */
+static void paging_handle_pending_requests(struct gsm_bts_paging_state *paging_bts)
+{
+	struct gsm_paging_request *request = NULL;
+
+	/*
+	 * Determine if the pending_requests list is empty and
+	 * return then.
+	 */
+	if (llist_empty(&paging_bts->pending_requests)) {
+		/* since the list is empty, no need to reschedule the timer */
+		return;
+	}
+
+	/*
+	 * In case the BTS does not provide us with load indication and we
+	 * ran out of slots, call an autofill routine. It might be that the
+	 * BTS did not like our paging messages and then we have counted down
+	 * to zero and we do not get any messages.
+	 */
+	if (paging_bts->available_slots == 0) {
+		paging_bts->credit_timer.cb = paging_give_credit;
+		paging_bts->credit_timer.data = paging_bts;
+		bsc_schedule_timer(&paging_bts->credit_timer, 5, 0);
+		return;
+	}
+
+	request = llist_entry(paging_bts->pending_requests.next,
+			      struct gsm_paging_request, entry);
+
+	/* we need to determine the number of free channels */
+	if (paging_bts->free_chans_need != -1) {
+		if (can_send_pag_req(request->bts, request->chan_type) != 0)
+			goto skip_paging;
+	}
+
+	/* handle the paging request now */
+	page_ms(request);
+	paging_bts->available_slots--;
+	request->attempts++;
+
+	/* take the current and add it to the back */
+	llist_del(&request->entry);
+	llist_add_tail(&request->entry, &paging_bts->pending_requests);
+
+skip_paging:
+	bsc_schedule_timer(&paging_bts->work_timer, PAGING_TIMER);
+}
+
+static void paging_worker(void *data)
+{
+	struct gsm_bts_paging_state *paging_bts = data;
+
+	paging_handle_pending_requests(paging_bts);
+}
+
+void paging_init(struct gsm_bts *bts)
+{
+	bts->paging.bts = bts;
+	INIT_LLIST_HEAD(&bts->paging.pending_requests);
+	bts->paging.work_timer.cb = paging_worker;
+	bts->paging.work_timer.data = &bts->paging;
+
+	/* Large number, until we get a proper message */
+	bts->paging.available_slots = 20;
+}
+
+static int paging_pending_request(struct gsm_bts_paging_state *bts,
+				struct gsm_subscriber *subscr) {
+	struct gsm_paging_request *req;
+
+	llist_for_each_entry(req, &bts->pending_requests, entry) {
+		if (subscr == req->subscr)
+			return 1;
+	}
+
+	return 0;	
+}
+
+static void paging_T3113_expired(void *data)
+{
+	struct gsm_paging_request *req = (struct gsm_paging_request *)data;
+	void *cbfn_param;
+	gsm_cbfn *cbfn;
+	int msg;
+
+	LOGP(DPAG, LOGL_INFO, "T3113 expired for request %p (%s)\n",
+		req, req->subscr->imsi);
+
+	/* must be destroyed before calling cbfn, to prevent double free */
+	counter_inc(req->bts->network->stats.paging.expired);
+	cbfn_param = req->cbfn_param;
+	cbfn = req->cbfn;
+
+	/* did we ever manage to page the subscriber */
+	msg = req->attempts > 0 ? GSM_PAGING_EXPIRED : GSM_PAGING_BUSY;
+
+	/* destroy it now. Do not access req afterwards */
+	paging_remove_request(&req->bts->paging, req);
+
+	if (cbfn)
+		cbfn(GSM_HOOK_RR_PAGING, msg, NULL, NULL,
+			  cbfn_param);
+}
+
+static int _paging_request(struct gsm_bts *bts, struct gsm_subscriber *subscr,
+			    int type, gsm_cbfn *cbfn, void *data)
+{
+	struct gsm_bts_paging_state *bts_entry = &bts->paging;
+	struct gsm_paging_request *req;
+
+	if (paging_pending_request(bts_entry, subscr)) {
+		LOGP(DPAG, LOGL_INFO, "Paging request already pending for %s\n", subscr->imsi);
+		return -EEXIST;
+	}
+
+	LOGP(DPAG, LOGL_DEBUG, "Start paging of subscriber %llu on bts %d.\n",
+		subscr->id, bts->nr);
+	req = talloc_zero(tall_paging_ctx, struct gsm_paging_request);
+	req->subscr = subscr_get(subscr);
+	req->bts = bts;
+	req->chan_type = type;
+	req->cbfn = cbfn;
+	req->cbfn_param = data;
+	req->T3113.cb = paging_T3113_expired;
+	req->T3113.data = req;
+	bsc_schedule_timer(&req->T3113, bts->network->T3113, 0);
+	llist_add_tail(&req->entry, &bts_entry->pending_requests);
+	paging_schedule_if_needed(bts_entry);
+
+	return 0;
+}
+
+int paging_request(struct gsm_network *network, struct gsm_subscriber *subscr,
+		   int type, gsm_cbfn *cbfn, void *data)
+{
+	struct gsm_bts *bts = NULL;
+	int num_pages = 0;
+
+	counter_inc(network->stats.paging.attempted);
+
+	/* start paging subscriber on all BTS within Location Area */
+	do {
+		int rc;
+
+		bts = gsm_bts_by_lac(network, subscr->lac, bts);
+		if (!bts)
+			break;
+
+		/* skip all currently inactive TRX */
+		if (!trx_is_usable(bts->c0))
+			continue;
+
+		num_pages++;
+
+		/* Trigger paging, pass any error to caller */
+		rc = _paging_request(bts, subscr, type, cbfn, data);
+		if (rc < 0)
+			return rc;
+	} while (1);
+
+	if (num_pages == 0)
+		counter_inc(network->stats.paging.detached);
+
+	return num_pages;
+}
+
+
+/* we consciously ignore the type of the request here */
+static void _paging_request_stop(struct gsm_bts *bts, struct gsm_subscriber *subscr,
+				 struct gsm_subscriber_connection *conn,
+				 struct msgb *msg)
+{
+	struct gsm_bts_paging_state *bts_entry = &bts->paging;
+	struct gsm_paging_request *req, *req2;
+
+	llist_for_each_entry_safe(req, req2, &bts_entry->pending_requests,
+				 entry) {
+		if (req->subscr == subscr) {
+			if (conn && req->cbfn) {
+				LOGP(DPAG, LOGL_DEBUG, "Stop paging on bts %d, calling cbfn.\n", bts->nr);
+				req->cbfn(GSM_HOOK_RR_PAGING, GSM_PAGING_SUCCEEDED,
+					  msg, conn, req->cbfn_param);
+			} else
+				LOGP(DPAG, LOGL_DEBUG, "Stop paging on bts %d silently.\n", bts->nr);
+			paging_remove_request(&bts->paging, req);
+			break;
+		}
+	}
+}
+
+/* Stop paging on all other bts' */
+void paging_request_stop(struct gsm_bts *_bts, struct gsm_subscriber *subscr,
+			 struct gsm_subscriber_connection *conn,
+			 struct msgb *msg)
+{
+	struct gsm_bts *bts = NULL;
+
+	if (_bts)
+		_paging_request_stop(_bts, subscr, conn, msg);
+
+	do {
+		/*
+		 * FIXME: Don't use the lac of the subscriber...
+		 * as it might have magically changed the lac.. use the
+		 * location area of the _bts as reconfiguration of the
+		 * network is probably happening less often.
+		 */
+		bts = gsm_bts_by_lac(subscr->net, subscr->lac, bts);
+		if (!bts)
+			break;
+
+		/* Stop paging */
+		if (bts != _bts)
+			_paging_request_stop(bts, subscr, NULL, NULL);
+	} while (1);
+}
+
+void paging_update_buffer_space(struct gsm_bts *bts, u_int16_t free_slots)
+{
+	bsc_del_timer(&bts->paging.credit_timer);
+	bts->paging.available_slots = free_slots;
+	paging_schedule_if_needed(&bts->paging);
+}