host layer23: add a small cbch_sniff application

Tune to the ARFCN specified on the commandline (-a).  Then, if
a CBCH Channel Description IE is found in System Information Type 4,
switch to dedicated mode on that particular channel to receive
the CBCH.

2 files changed, 190 insertions, 3 deletions

diff --git a/src/host/layer23/src/misc/Makefile.am b/src/host/layer23/src/misc/Makefile.am
index da2628e5..f8a0b737 100644
--- a/src/host/layer23/src/misc/Makefile.am
+++ b/src/host/layer23/src/misc/Makefile.am
@@ -2,7 +2,7 @@ INCLUDES = $(all_includes) -I$(top_srcdir)/include
 AM_CFLAGS = -Wall $(LIBOSMOCORE_CFLAGS)
 LDADD = ../common/liblayer23.a $(LIBOSMOCORE_LIBS)
 
-bin_PROGRAMS = bcch_scan layer23 echo_test cell_log
+bin_PROGRAMS = bcch_scan layer23 echo_test cell_log cbch_sniff
 
 bcch_scan_SOURCES = ../common/main.c app_bcch_scan.c bcch_scan.c
 layer23_SOURCES   = ../common/main.c app_phone.c layer3.c rslms.c
@@ -10,5 +10,4 @@ echo_test_SOURCES = ../common/main.c app_echo_test.c
 cell_log_LDADD = $(LDADD) -lm
 cell_log_SOURCES = ../common/main.c app_cell_log.c cell_log.c \
 			../../../gsmmap/geo.c
-
-
+cbch_sniff_SOURCES = ../common/main.c app_cbch_sniff.c
diff --git a/src/host/layer23/src/misc/app_cbch_sniff.c b/src/host/layer23/src/misc/app_cbch_sniff.c
new file mode 100644
index 00000000..19a9aced
--- /dev/null
+++ b/src/host/layer23/src/misc/app_cbch_sniff.c
@@ -0,0 +1,188 @@
+/* CBCH passive sniffer */
+
+/* (C) 2010 by Holger Hans Peter Freyther
+ * (C) 2010 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010 by Alex Badea <vamposdecampos@gmail.com>
+ *
+ * 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 <osmocom/bb/common/osmocom_data.h>
+#include <osmocom/bb/common/l1ctl.h>
+#include <osmocom/bb/common/lapdm.h>
+#include <osmocom/bb/common/logging.h>
+#include <osmocom/bb/misc/layer3.h>
+
+#include <osmocore/msgb.h>
+#include <osmocore/talloc.h>
+#include <osmocore/select.h>
+#include <osmocore/signal.h>
+#include <osmocore/rsl.h>
+
+struct osmocom_ms *g_ms;
+struct gsm48_sysinfo g_sysinfo = {};
+
+static int try_cbch(struct osmocom_ms *ms, struct gsm48_sysinfo *s)
+{
+	if (!s->si1 || !s->si4)
+		return 0;
+	if (!s->chan_nr) {
+		LOGP(DRR, LOGL_INFO, "no CBCH chan_nr found\n");
+		return 0;
+	}
+
+	if (s->h) {
+		LOGP(DRR, LOGL_INFO, "chan_nr = 0x%02x TSC = %d  MAIO = %d  "
+			"HSN = %d  hseq (%d): %s\n",
+			s->chan_nr, s->tsc, s->maio, s->hsn,
+			s->hopp_len,
+			hexdump((unsigned char *) s->hopping, s->hopp_len * 2));
+		return l1ctl_tx_dm_est_req_h1(ms,
+			s->maio, s->hsn, s->hopping, s->hopp_len,
+			s->chan_nr, s->tsc,
+			GSM48_CMODE_SIGN);
+	} else {
+		LOGP(DRR, LOGL_INFO, "chan_nr = 0x%02x TSC = %d  ARFCN = %d\n",
+			s->chan_nr, s->tsc, s->arfcn);
+		return l1ctl_tx_dm_est_req_h0(ms, s->arfcn,
+			s->chan_nr, s->tsc, GSM48_CMODE_SIGN);
+	}
+}
+
+
+/* receive BCCH at RR layer */
+static int bcch(struct osmocom_ms *ms, struct msgb *msg)
+{
+	struct gsm48_system_information_type_header *sih = msgb_l3(msg);
+	struct gsm48_sysinfo *s = &g_sysinfo;
+
+	if (msgb_l3len(msg) != 23) {
+		LOGP(DRR, LOGL_NOTICE, "Invalid BCCH message length\n");
+		return -EINVAL;
+	}
+	switch (sih->system_information) {
+	case GSM48_MT_RR_SYSINFO_1:
+		LOGP(DRR, LOGL_INFO, "New SYSTEM INFORMATION 1\n");
+		gsm48_decode_sysinfo1(s,
+			(struct gsm48_system_information_type_1 *) sih,
+			msgb_l3len(msg));
+		return try_cbch(ms, s);
+	case GSM48_MT_RR_SYSINFO_4:
+		LOGP(DRR, LOGL_INFO, "New SYSTEM INFORMATION 4\n");
+		gsm48_decode_sysinfo4(s,
+			(struct gsm48_system_information_type_4 *) sih,
+			msgb_l3len(msg));
+		return try_cbch(ms, s);
+	default:
+		return 0;
+	}
+}
+
+static int unit_data_ind(struct osmocom_ms *ms, struct msgb *msg)
+{
+	struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
+	struct tlv_parsed tv;
+	uint8_t ch_type, ch_subch, ch_ts;
+
+	DEBUGP(DRSL, "RSLms UNIT DATA IND chan_nr=0x%02x link_id=0x%02x\n",
+		rllh->chan_nr, rllh->link_id);
+
+	rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
+	if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
+		DEBUGP(DRSL, "UNIT_DATA_IND without L3 INFO ?!?\n");
+		return -EIO;
+	}
+	msg->l3h = (uint8_t *) TLVP_VAL(&tv, RSL_IE_L3_INFO);
+
+	rsl_dec_chan_nr(rllh->chan_nr, &ch_type, &ch_subch, &ch_ts);
+	switch (ch_type) {
+	case RSL_CHAN_BCCH:
+		return bcch(ms, msg);
+	default:
+		return 0;
+	}
+}
+
+static int rcv_rll(struct osmocom_ms *ms, struct msgb *msg)
+{
+	struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
+	int msg_type = rllh->c.msg_type;
+
+	if (msg_type == RSL_MT_UNIT_DATA_IND) {
+		unit_data_ind(ms, msg);
+	} else
+		LOGP(DRSL, LOGL_NOTICE, "RSLms message unhandled\n");
+
+	msgb_free(msg);
+
+	return 0;
+}
+
+static int rcv_rsl(struct msgb *msg, struct osmocom_ms *ms)
+{
+	struct abis_rsl_common_hdr *rslh = msgb_l2(msg);
+	int rc = 0;
+
+	switch (rslh->msg_discr & 0xfe) {
+	case ABIS_RSL_MDISC_RLL:
+		rc = rcv_rll(ms, msg);
+		break;
+	default:
+		LOGP(DRSL, LOGL_NOTICE, "unknown RSLms msg_discr 0x%02x\n",
+			rslh->msg_discr);
+		msgb_free(msg);
+		rc = -EINVAL;
+		break;
+	}
+
+	return rc;
+}
+
+static int signal_cb(unsigned int subsys, unsigned int signal,
+		     void *handler_data, void *signal_data)
+{
+	struct osmocom_ms *ms;
+
+	if (subsys != SS_L1CTL)
+		return 0;
+
+	switch (signal) {
+	case S_L1CTL_RESET:
+	case S_L1CTL_FBSB_ERR:
+		ms = g_ms;
+		return l1ctl_tx_fbsb_req(ms, ms->test_arfcn,
+			L1CTL_FBSB_F_FB01SB, 100, 0, CCCH_MODE_COMBINED);
+	case S_L1CTL_FBSB_RESP:
+		return 0;
+	}
+	return 0;
+}
+
+int l23_app_init(struct osmocom_ms *ms)
+{
+	/* don't do layer3_init() as we don't want an actualy L3 */
+
+	g_ms = ms;
+	osmol2_register_handler(ms, &rcv_rsl);
+
+	l1ctl_tx_reset_req(ms, L1CTL_RES_T_FULL);
+	/* FIXME: L1CTL_RES_T_FULL doesn't reset dedicated mode
+	 * (if previously set), so we release it here. */
+	l1ctl_tx_dm_rel_req(ms);
+	return register_signal_handler(SS_L1CTL, &signal_cb, NULL);
+}