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-rw-r--r--src/libbsc/paging.c395
1 files changed, 395 insertions, 0 deletions
diff --git a/src/libbsc/paging.c b/src/libbsc/paging.c
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+/* 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);
+}