bsc/mminfo: Patch timezone and DST in MM Info messages

This adds in-place patching of the time information in the
MM INFORMATION message. The timezone in the 'Local time zone' and
the 'Universal time and local time zone' information elements
and the offset in the 'Network Daylight Saving Time' information
element are optionally set.

The new values are determined by the 'timezone' vty command in the
config_net_bts node. That command is extended by an optional
DST offset parameter.

Tests are provided for the vty part and for the plain
bsc_scan_msc_msg() function.

Sponsored-by: On-Waves ehf
Ticket: OW#978

1 files changed, 65 insertions, 1 deletions

diff --git a/openbsc/src/osmo-bsc/osmo_bsc_filter.c b/openbsc/src/osmo-bsc/osmo_bsc_filter.c
index 957ceaf95..608f52552 100644
--- a/openbsc/src/osmo-bsc/osmo_bsc_filter.c
+++ b/openbsc/src/osmo-bsc/osmo_bsc_filter.c
@@ -251,6 +251,65 @@ int bsc_send_welcome_ussd(struct gsm_subscriber_connection *conn)
 	return 0;
 }
 
+static int bsc_patch_mm_info(struct gsm_subscriber_connection *conn,
+		uint8_t *data, unsigned int length)
+{
+	struct tlv_parsed tp;
+	int parse_res;
+	struct gsm_bts *bts = conn->bts;
+	int tzunits;
+	uint8_t tzbsd = 0;
+	uint8_t dst = 0;
+
+	parse_res = tlv_parse(&tp, &gsm48_mm_att_tlvdef, data, length, 0, 0);
+	if (parse_res <= 0 && parse_res != -3)
+		return 0;
+
+	/* Is TZ patching enabled? */
+	if (!bts->tz.override)
+		return 0;
+
+	/* Convert tz.hr and tz.mn to units */
+	if (bts->tz.hr < 0) {
+		tzunits = -bts->tz.hr*4;
+		tzbsd |= 0x08;
+	} else
+		tzunits = bts->tz.hr*4;
+
+	tzunits = tzunits + (bts->tz.mn/15);
+
+	tzbsd |= (tzunits % 10)*0x10 + (tzunits / 10);
+
+	/* Convert DST value */
+	if (bts->tz.dst >= 0 && bts->tz.dst <= 2)
+		dst = bts->tz.dst;
+
+	if (TLVP_PRESENT(&tp, GSM48_IE_UTC)) {
+		LOGP(DMSC, LOGL_DEBUG,
+			"Changing 'Local time zone' from 0x%02x to 0x%02x.\n",
+			TLVP_VAL(&tp, GSM48_IE_UTC)[6], tzbsd);
+		((uint8_t *)(TLVP_VAL(&tp, GSM48_IE_UTC)))[0] = tzbsd;
+	}
+	if (TLVP_PRESENT(&tp, GSM48_IE_NET_TIME_TZ)) {
+		LOGP(DMSC, LOGL_DEBUG,
+			"Changing 'Universal time and local time zone' TZ from "
+			"0x%02x to 0x%02x.\n",
+			TLVP_VAL(&tp, GSM48_IE_NET_TIME_TZ)[6], tzbsd);
+		((uint8_t *)(TLVP_VAL(&tp, GSM48_IE_NET_TIME_TZ)))[6] = tzbsd;
+	}
+#ifdef GSM48_IE_NET_DST
+	if (TLVP_PRESENT(&tp, GSM48_IE_NET_DST)) {
+		LOGP(DMSC, LOGL_DEBUG,
+			"Changing 'Network daylight saving time' from "
+			"0x%02x to 0x%02x.\n",
+			TLVP_VAL(&tp, GSM48_IE_NET_DST)[0], dst);
+		((uint8_t *)(TLVP_VAL(&tp, GSM48_IE_NET_DST)))[0] = dst;
+	}
+#endif
+
+	return 0;
+}
+
 /**
  * Messages coming back from the MSC.
  */
@@ -261,13 +320,16 @@ int bsc_scan_msc_msg(struct gsm_subscriber_connection *conn, struct msgb *msg)
 	struct gsm48_loc_area_id *lai;
 	struct gsm48_hdr *gh;
 	uint8_t mtype;
+	int length = msgb_l3len(msg);
 
-	if (msgb_l3len(msg) < sizeof(*gh)) {
+	if (length < sizeof(*gh)) {
 		LOGP(DMSC, LOGL_ERROR, "GSM48 header does not fit.\n");
 		return -1;
 	}
 
 	gh = (struct gsm48_hdr *) msgb_l3(msg);
+	length -= (const char *)&gh->data[0] - (const char *)gh;
+
 	mtype = gh->msg_type & 0xbf;
 	net = conn->bts->network;
 	msc = conn->sccp_con->msc;
@@ -285,6 +347,8 @@ int bsc_scan_msc_msg(struct gsm_subscriber_connection *conn, struct msgb *msg)
 		if (conn->sccp_con->new_subscriber)
 			return send_welcome_ussd(conn);
 		return 0;
+	} else if (mtype == GSM48_MT_MM_INFO) {
+		bsc_patch_mm_info(conn, &gh->data[0], length);
 	}
 
 	return 0;