Replace template-based SYSTEM INFORMATION with real implementation

Before this commit, OpenBSC used templates for the SYSTEM INFO
1, 2, 3, 4, 5 and 6 messages.  Those templates were patched in
various places to reflect the network config like ARFCN.

Now, we actually generate those SI messages ourselves, using
values from the configuration file, and even calculating neighbor
cell lists.

All bts'es that you have configured in OpenBSC will end up in
the neighbor cell list - which should be more than sufficient for
the current small-single-site networks.

1 files changed, 427 insertions, 0 deletions

diff --git a/openbsc/src/system_information.c b/openbsc/src/system_information.c
new file mode 100644
index 000000000..d6d166c79
--- /dev/null
+++ b/openbsc/src/system_information.c
@@ -0,0 +1,427 @@
+/* GSM 04.08 System Information (SI) encoding and decoding
+ * 3GPP TS 04.08 version 7.21.0 Release 1998 / ETSI TS 100 940 V7.21.0 */
+
+/* (C) 2008-2009 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 General Public License as published by
+ * the Free Software Foundation; either version 2 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <errno.h>
+#include <string.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+
+#include <openbsc/gsm_04_08.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/abis_rsl.h>
+#include <openbsc/rest_octets.h>
+
+#define GSM48_CELL_CHAN_DESC_SIZE	16
+#define GSM_MACBLOCK_LEN 		23
+#define GSM_MACBLOCK_PADDING		0x2b
+
+static int cchan_list_bm0_set_arfcn(u_int8_t *chan_list, unsigned int arfcn)
+{
+	unsigned int byte, bit;
+
+	if (arfcn > 124)
+		return -EINVAL;
+
+	byte = arfcn / 8;
+	bit = arfcn % 8;
+
+	chan_list[GSM48_CELL_CHAN_DESC_SIZE-byte] |= (1 << bit);
+
+	return 0;
+}
+
+static int cchan_list_bmrel_set_arfcn(u_int8_t *chan_list, unsigned int arfcn)
+{
+	unsigned int byte, bit;
+	unsigned int min_arfcn;
+	unsigned int bitno;
+
+	min_arfcn = (chan_list[0] & 1) << 9;
+	min_arfcn |= chan_list[1] << 1;
+	min_arfcn |= (chan_list[2] >> 7) & 1;
+
+	/* The lower end of our bitmaks is always implicitly included */
+	if (arfcn == min_arfcn)
+		return 0;
+
+	if (arfcn < min_arfcn)
+		return -EINVAL;
+	if (arfcn > min_arfcn + 111)
+		return -EINVAL;
+
+	bitno = (arfcn - min_arfcn);
+	byte = bitno / 8;
+	bit = bitno % 8;
+
+	chan_list[2 + byte] |= 1 << (7 - bit);
+
+	return 0;
+}
+
+/* generate a cell channel list as per Section 10.5.2.1b of 04.08 */
+static int generate_cell_chan_list(u_int8_t *chan_list, const struct gsm_bts *bts)
+{
+	struct gsm_bts_trx *trx;
+	int rc, min = 1024, max = 0;
+
+	memset(chan_list, 0, 16);
+
+	/* GSM900-only handsets only support 'bit map 0 format' */
+	if (bts->band == GSM_BAND_900) {
+		chan_list[0] = 0;
+		llist_for_each_entry(trx, &bts->trx_list, list) {
+			rc = cchan_list_bm0_set_arfcn(chan_list, trx->arfcn);
+			if (rc < 0)
+				return rc;
+		}
+		return 0;
+	}
+
+	/* We currently only support the 'Variable bitmap format' */
+	chan_list[0] = 0x8e;
+
+	llist_for_each_entry(trx, &bts->trx_list, list) {
+		if (trx->arfcn < min)
+			min = trx->arfcn;
+		if (trx->arfcn > max)
+			max = trx->arfcn;
+	}
+
+	if ((max - min) > 111)
+		return -EINVAL;
+
+	chan_list[0] |= (min >> 9) & 1;
+	chan_list[1] = (min >> 1);
+	chan_list[2] = (min & 1) << 7;
+
+	llist_for_each_entry(trx, &bts->trx_list, list) {
+		rc = cchan_list_bmrel_set_arfcn(chan_list, trx->arfcn);
+		if (rc < 0)
+			return rc;
+	}
+
+	return 0;
+}
+
+/* generate a cell channel list as per Section 10.5.2.1b of 04.08 */
+static int generate_bcch_chan_list(u_int8_t *chan_list, const struct gsm_bts *bts)
+{
+	struct gsm_bts *cur_bts;
+	struct gsm_bts_trx *trx;
+	int rc, min = 1024, max = 0;
+
+	memset(chan_list, 0, 16);
+
+	/* GSM900-only handsets only support 'bit map 0 format' */
+	if (bts->band == GSM_BAND_900) {
+		chan_list[0] = 0;
+		llist_for_each_entry(cur_bts, &bts->list, list) {
+			trx = cur_bts->c0;
+			rc = cchan_list_bm0_set_arfcn(chan_list, trx->arfcn);
+			if (rc < 0)
+				return rc;
+		}
+		return 0;
+	}
+
+	/* We currently only support the 'Variable bitmap format' */
+	chan_list[0] = 0x8e;
+
+	llist_for_each_entry(cur_bts, &bts->list, list) {
+		if (&cur_bts->list == &bts->network->bts_list)
+			continue;
+		trx = cur_bts->c0;
+		if (trx->arfcn < min)
+			min = trx->arfcn;
+		if (trx->arfcn > max)
+			max = trx->arfcn;
+	}
+
+	if ((max - min) > 111)
+		return -EINVAL;
+
+	chan_list[0] |= (min >> 9) & 1;
+	chan_list[1] = (min >> 1);
+	chan_list[2] = (min & 1) << 7;
+
+	llist_for_each_entry(cur_bts, &bts->list, list) {
+		if (&cur_bts->list == &bts->network->bts_list)
+			continue;
+		trx = cur_bts->c0;
+		rc = cchan_list_bmrel_set_arfcn(chan_list, trx->arfcn);
+		if (rc < 0)
+			return rc;
+	}
+
+	return 0;
+}
+
+static int generate_si1(u_int8_t *output, const struct gsm_bts *bts)
+{
+	int rc;
+	struct gsm48_system_information_type_1 *si1 =
+		(struct gsm48_system_information_type_1 *) output;
+
+	memset(si1, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);
+
+	si1->header.l2_plen = (21 << 2) | 1;
+	si1->header.rr_protocol_discriminator = GSM48_PDISC_RR;
+	si1->header.skip_indicator = 0;
+	si1->header.system_information = GSM48_MT_RR_SYSINFO_1;
+
+	rc = generate_cell_chan_list(si1->cell_channel_description, bts);
+	if (rc < 0)
+		return rc;
+
+	si1->rach_control = bts->si_common.rach_control;
+
+	/* SI1 Rest Octets (10.5.2.32), contains NCH position */
+	rest_octets_si1(si1->rest_octets, NULL);
+
+	return GSM_MACBLOCK_LEN;
+}
+
+static int generate_si2(u_int8_t *output, const struct gsm_bts *bts)
+{
+	int rc;
+	struct gsm48_system_information_type_2 *si2 =
+		(struct gsm48_system_information_type_2 *) output;
+
+	memset(si2, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);
+
+	si2->header.l2_plen = (22 << 2) | 1;
+	si2->header.rr_protocol_discriminator = GSM48_PDISC_RR;
+	si2->header.skip_indicator = 0;
+	si2->header.system_information = GSM48_MT_RR_SYSINFO_2;
+
+	rc = generate_bcch_chan_list(si2->bcch_frequency_list, bts);
+	if (rc < 0)
+		return rc;
+
+	si2->ncc_permitted = bts->si_common.ncc_permitted;
+	si2->rach_control = bts->si_common.rach_control;
+
+	return GSM_MACBLOCK_LEN;
+}
+
+struct gsm48_si_ro_info si_info = {
+	.selection_params = {
+		.present = 0,
+	},
+	.power_offset = {
+		.present = 0,
+	},
+	.si2ter_indicator = 0,
+	.early_cm_ctrl = 1,
+	.scheduling = {
+		.present = 0,
+	},
+	.gprs_ind = {
+		.si13_position = 0,
+		.ra_colour = 0,
+		.present = 0,
+	},
+	.lsa_params = {
+		.present = 0,
+	},
+	.cell_id = 0,	/* FIXME: doesn't the bts have this? */
+	.break_ind = 0,
+};
+
+static int generate_si3(u_int8_t *output, const struct gsm_bts *bts)
+{
+	struct gsm48_system_information_type_3 *si3 =
+		(struct gsm48_system_information_type_3 *) output;
+
+	memset(si3, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);
+
+	si3->header.l2_plen = (18 << 2) | 1;
+	si3->header.rr_protocol_discriminator = GSM48_PDISC_RR;
+	si3->header.skip_indicator = 0;
+	si3->header.system_information = GSM48_MT_RR_SYSINFO_3;
+
+	si3->cell_identity = htons(bts->cell_identity);
+	gsm0408_generate_lai(&si3->lai, bts->network->country_code,
+			     bts->network->network_code,
+			     bts->location_area_code);
+	si3->control_channel_desc = bts->si_common.chan_desc;
+	si3->cell_options = bts->si_common.cell_options;
+	si3->cell_sel_par = bts->si_common.cell_sel_par;
+	si3->rach_control = bts->si_common.rach_control;
+
+	/* SI3 Rest Octets (10.5.2.34), containing
+		CBQ, CELL_RESELECT_OFFSET, TEMPORARY_OFFSET, PENALTY_TIME
+		Power Offset, 2ter Indicator, Early Classmark Sending,
+		Scheduling if and WHERE, GPRS Indicator, SI13 position */
+	rest_octets_si3(si3->rest_octets, &si_info);
+
+	return GSM_MACBLOCK_LEN;
+}
+
+static int generate_si4(u_int8_t *output, const struct gsm_bts *bts)
+{
+	struct gsm48_system_information_type_4 *si4 =
+		(struct gsm48_system_information_type_4 *) output;
+
+	/* length of all IEs present except SI4 rest octets and l2_plen */
+	int l2_plen = sizeof(*si4) - 1;
+
+	memset(si4, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);
+
+	si4->header.rr_protocol_discriminator = GSM48_PDISC_RR;
+	si4->header.skip_indicator = 0;
+	si4->header.system_information = GSM48_MT_RR_SYSINFO_4;
+
+	gsm0408_generate_lai(&si4->lai, bts->network->country_code,
+			     bts->network->network_code,
+			     bts->location_area_code);
+	si4->cell_sel_par = bts->si_common.cell_sel_par;
+	si4->rach_control = bts->si_common.rach_control;
+
+	/* Optional: CBCH Channel Description + CBCH Mobile Allocation */
+
+	si4->header.l2_plen = (l2_plen << 2) | 1;
+
+	/* SI4 Rest Octets (10.5.2.35), containing
+		Optional Power offset, GPRS Indicator,
+		Cell Identity, LSA ID, Selection Parameter */
+	rest_octets_si4(si4->data, &si_info);
+
+	return GSM_MACBLOCK_LEN;
+}
+
+static int generate_si5(u_int8_t *output, const struct gsm_bts *bts)
+{
+	struct gsm48_system_information_type_5 *si5 =
+		(struct gsm48_system_information_type_5 *) output;
+	int rc;
+
+	memset(si5, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);
+
+	/* l2 pseudo length, not part of msg: 18 */
+	si5->rr_protocol_discriminator = GSM48_PDISC_RR;
+	si5->skip_indicator = 0;
+	si5->system_information = GSM48_MT_RR_SYSINFO_5;
+	rc = generate_bcch_chan_list(si5->bcch_frequency_list, bts);
+	if (rc < 0)
+		return rc;
+
+	/* 04.08 9.1.37: L2 Pseudo Length of 18 */
+	return 18;
+}
+
+static int generate_si6(u_int8_t *output, const struct gsm_bts *bts)
+{
+	struct gsm48_system_information_type_6 *si6 =
+		(struct gsm48_system_information_type_6 *) output;
+
+	memset(si6, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);
+
+	/* l2 pseudo length, not part of msg: 11 */
+	si6->rr_protocol_discriminator = GSM48_PDISC_RR;
+	si6->skip_indicator = 0;
+	si6->system_information = GSM48_MT_RR_SYSINFO_6;
+	si6->cell_identity = htons(bts->cell_identity);
+	gsm0408_generate_lai(&si6->lai, bts->network->country_code,
+			     bts->network->network_code,
+			     bts->location_area_code);
+	si6->cell_options = bts->si_common.cell_options;
+	si6->ncc_permitted = bts->si_common.ncc_permitted;
+
+	/* SI6 Rest Octets: 10.5.2.35a: PCH / NCH info, VBS/VGCS options */
+
+	return 18;
+}
+
+static struct gsm48_si13_info si13_default = {
+	.cell_opts = {
+		.nmo 		= GPRS_NMO_III,
+		.t3168		= 1000,
+		.t3192		= 1000,
+		.drx_timer_max	= 1,
+		.bs_cv_max	= 15,
+	},
+	.pwr_ctrl_pars = {
+		.alpha		= 10,	/* a = 1.0 */
+		.t_avg_w	= 25,
+		.t_avg_t	= 25,
+		.pc_meas_chan	= 0, 	/* downling measured on CCCH */
+		.n_avg_i	= 15,
+	},
+	.bcch_change_mark	= 0,
+	.si_change_field	= 0,
+	.pbcch_present		= 0,
+	{
+		.no_pbcch = {
+			.rac		= 0,
+			.spgc_ccch_sup 	= 0,
+			.net_ctrl_ord	= 0,
+			.prio_acc_thr	= 0,
+		},
+	},
+};
+
+static int generate_si13(u_int8_t *output, const struct gsm_bts *bts)
+{
+	struct gsm48_system_information_type_13 *si13 =
+		(struct gsm48_system_information_type_13 *) output;
+	int ret;
+
+	memset(si13, GSM_MACBLOCK_PADDING, GSM_MACBLOCK_LEN);
+
+	si13->header.rr_protocol_discriminator = GSM48_PDISC_RR;
+	si13->header.skip_indicator = 0;
+	si13->header.system_information = GSM48_MT_RR_SYSINFO_13;
+
+	ret = rest_octets_si13(si13->rest_octets, &si13_default);
+	if (ret < 0)
+		return ret;
+
+	si13->header.l2_plen = ret & 0xff;
+
+	return GSM_MACBLOCK_LEN;
+}
+
+int gsm_generate_si(u_int8_t *output, struct gsm_bts *bts, int type)
+{
+	switch (type) {
+	case RSL_SYSTEM_INFO_1:
+		return generate_si1(output, bts);
+	case RSL_SYSTEM_INFO_2:
+		return generate_si2(output, bts);
+	case RSL_SYSTEM_INFO_3:
+		return generate_si3(output, bts);
+	case RSL_SYSTEM_INFO_4:
+		return generate_si4(output, bts);
+	case RSL_SYSTEM_INFO_5:
+		return generate_si5(output, bts);
+	case RSL_SYSTEM_INFO_6:
+		return generate_si6(output, bts);
+	case RSL_SYSTEM_INFO_13:
+		return generate_si13(output, bts);
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}