[PATCH 3/3] layer23 cell_log: log CBCH cell info

[Alex Badea]

If System Information contained CBCH channel description,
tune to it and log SMSCB messages with a Geographical Scope
of Cell Wide (Immediate) -- these are typically used for
"Cell Info Display".

The CBCH timeout is set to a generous 8 seconds; this is because
we need 4 frames for reassembly, we usually miss the first, and we
might hit a burst of Null SMSCB messages.

Signed-off-by: Alex Badea <vamposdecampos at gmail.com>
---
 src/host/layer23/src/misc/cell_log.c |  107 +++++++++++++++++++++++++++++++++-
 1 files changed, 105 insertions(+), 2 deletions(-)

diff --git a/src/host/layer23/src/misc/cell_log.c b/src/host/layer23/src/misc/cell_log.c
index e6c5771..37aa271 100644
--- a/src/host/layer23/src/misc/cell_log.c
+++ b/src/host/layer23/src/misc/cell_log.c
@@ -26,6 +26,7 @@
 #include <stdlib.h>
 #include <time.h>
 #include <errno.h>
+#include <netinet/in.h>
 
 #include <l1ctl_proto.h>
 
@@ -34,7 +35,9 @@
 #include <osmocore/signal.h>
 #include <osmocore/msgb.h>
 #include <osmocore/gsm_utils.h>
+#include <osmocore/protocol/gsm_03_41.h>
 #include <osmocore/protocol/gsm_04_08.h>
+#include <osmocore/protocol/gsm_08_58.h>
 #include <osmocore/rsl.h>
 
 #include <osmocom/bb/common/l1ctl.h>
@@ -49,6 +52,7 @@
 #define READ_WAIT	2, 0
 #define RACH_MAX	2
 #define RACH_WAIT	0, 900000
+#define CBCH_WAIT	8, 0
 #define MIN_RXLEV	-106
 #define MAX_DIST	2000
 
@@ -57,6 +61,7 @@ enum {
 	SCAN_STATE_SYNC,
 	SCAN_STATE_READ,
 	SCAN_STATE_RACH,
+	SCAN_STATE_CBCH,
 };
 
 /* ranges of bands */
@@ -114,6 +119,7 @@ struct rach_ref {
 
 static void start_sync(void);
 static void start_rach(void);
+static void start_cbch(void);
 static void start_pm(void);
 
 static void log_gps(void)
@@ -227,6 +233,11 @@ static void timeout_cb(void *arg)
 		rach_count++;
 		start_rach();
 		break;
+	case SCAN_STATE_CBCH:
+		LOGP(DRR, LOGL_INFO, "Timeout reading CBCH\n");
+		l1ctl_tx_dm_rel_req(ms);
+		start_sync();
+		break;
 	}
 }
 
@@ -244,6 +255,33 @@ static void start_timer(int sec, int micro)
 	bsc_schedule_timer(&timer, sec, micro);
 }
 
+static void start_cbch(void)
+{
+	struct gsm48_sysinfo *s = &sysinfo;
+	int res;
+
+	if (!s->chan_nr) {
+		LOGP(DRR, LOGL_DEBUG, "No CBCH description in sysinfo\n");
+		res = -1;
+	} else if (s->h) {
+		res = 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 {
+		res = l1ctl_tx_dm_est_req_h0(ms, s->arfcn,
+			s->chan_nr, s->tsc, GSM48_CMODE_SIGN);
+	}
+
+	if (res < 0) {
+		start_sync();
+		return;
+	}
+
+	state = SCAN_STATE_CBCH;
+	start_timer(CBCH_WAIT);
+}
+
 static void start_rach(void)
 {
 	struct gsm48_sysinfo *s = &sysinfo;
@@ -253,7 +291,7 @@ static void start_rach(void)
 
 	if (rach_count == RACH_MAX) {
 		log_sysinfo();
-		start_sync();
+		start_cbch();
 		return;
 	}
 
@@ -426,7 +464,7 @@ static int ta_result(uint8_t ta)
 	}
 
 	log_sysinfo();
-	start_sync();
+	start_cbch();
 
 	return 0;
 }
@@ -730,6 +768,66 @@ int chan_conf(struct osmocom_ms *ms, struct msgb *msg)
 	return 0;
 }
 
+static int sms_cb_cmd(struct osmocom_ms *ms, struct msgb *msg)
+{
+	struct abis_rsl_cchan_hdr *ch = msgb_l2(msg);
+	struct tlv_parsed tv;
+	struct rsl_ie_cb_cmd_type *cmd_type;
+	struct gsm341_ms_message *cbmsg;
+	unsigned int cbmsglen;
+	char buf[256], *p;
+
+	rsl_tlv_parse(&tv, ch->data, msgb_l2len(msg) - sizeof(*ch));
+	if (!TLVP_PRESENT(&tv, RSL_IE_SMSCB_MSG) ||
+	    !TLVP_PRESENT(&tv, RSL_IE_CB_CMD_TYPE)) {
+		LOGP(DRR, LOGL_ERROR, "SMS_BC_CMD missing mandatory IEs\n");
+		return -EINVAL;
+	}
+
+	cmd_type = (struct rsl_ie_cb_cmd_type *) TLVP_VAL(&tv, RSL_IE_CB_CMD_TYPE);
+	cbmsg = (struct gsm341_ms_message *) TLVP_VAL(&tv, RSL_IE_SMSCB_MSG);
+	cbmsglen = TLVP_LEN(&tv, RSL_IE_SMSCB_MSG);
+	if (cbmsglen < sizeof(*cbmsg)) {
+		LOGP(DRR, LOGL_ERROR, "RSL_IE_SMSCB_MSG too short\n");
+		return -EINVAL;
+	}
+
+	if (cmd_type->command != RSL_CB_CMD_TYPE_NORMAL)
+		return 0;
+	if (cbmsg->serial.gs != GSM341_GS_CELL_WIDE_IMMED)
+		return 0;
+
+	gsm_7bit_decode(buf, cbmsg->data, cbmsglen - sizeof(*cbmsg));
+	if ((p = strchr(buf, '\r')))
+		*p = 0;
+
+	LOGP(DSUM, LOGL_INFO, "Cell info: code=%d update=%d id=%d text=\"%s\"\n",
+		cbmsg->serial.code_lo | (cbmsg->serial.code_hi << 6),
+		cbmsg->serial.update,
+		ntohs(cbmsg->msg_id),
+		buf);
+
+	LOGFILE("[cbch]\n");
+	LOGFILE("arfcn %d\n", sysinfo.arfcn);
+	LOGFILE("gs %d code %d update %d msg_id %d page %d numpages %d\n",
+		cbmsg->serial.gs,
+		cbmsg->serial.code_lo | (cbmsg->serial.code_hi << 6),
+		cbmsg->serial.update,
+		ntohs(cbmsg->msg_id),
+		cbmsg->page.current, cbmsg->page.total);
+	LOGFILE("text \"%s\"\n", buf);
+	LOGFILE("\n");
+	LOGFLUSH();
+
+	l1ctl_tx_dm_rel_req(ms);
+	stop_timer();
+
+	start_sync();
+
+	return 0;
+
+}
+
 static int rcv_cch(struct osmocom_ms *ms, struct msgb *msg)
 {
 	struct abis_rsl_cchan_hdr *ch = msgb_l2(msg);
@@ -744,6 +842,11 @@ static int rcv_cch(struct osmocom_ms *ms, struct msgb *msg)
 		msgb_free(msg);
 		return rc;
 	}
+	if (state == SCAN_STATE_CBCH && msg_type == RSL_MT_SMS_BC_CMD) {
+		rc = sms_cb_cmd(ms, msg);
+		msgb_free(msg);
+		return rc;
+	}
 
 	LOGP(DRSL, LOGL_NOTICE, "RSLms message unhandled\n");
 	msgb_free(msg);
-- 
1.7.0.4