Allow Gb PAGING-PS without P-TMSI

P-TMSI is optional IE, but IE is mandatory and hence always available.
Since the encoding is actually a Mobile Identity, the IMSI is used in
case P-TMSI is not available.

Change-Id: I4dbf8db04e81f98352a42ce34a5d91326be9bfd1

src/encoding.cpp

@@ -729,7 +729,7 @@ void Encoding::write_packet_downlink_assignment(RlcMacDownlink_t * block,
 }
 
 /* Generate paging request. See 44.018, sections 10 and 9.1.22 */
-int Encoding::write_paging_request(bitvec * dest, uint8_t *ptmsi, uint16_t ptmsi_len)
+int Encoding::write_paging_request(bitvec * dest, const uint8_t *mi, uint8_t mi_len)
 {
 	unsigned wp = 0;
 	int plen;
@@ -741,14 +741,9 @@ int Encoding::write_paging_request(bitvec * dest, uint8_t *ptmsi, uint16_t ptmsi
 	bitvec_write_field(dest, &wp,0x0,4);  // Page Mode
 	bitvec_write_field(dest, &wp,0x0,4);  // Channel Needed
 
-	// Mobile Identity
-	bitvec_write_field(dest, &wp,ptmsi_len+1,8);  // Mobile Identity length
-	bitvec_write_field(dest, &wp,0xf,4);          // unused
-	bitvec_write_field(dest, &wp,0x4,4);          // PTMSI type
-	for (int i = 0; i < ptmsi_len; i++)
-	{
-		bitvec_write_field(dest, &wp,ptmsi[i],8); // PTMSI
-	}
+	bitvec_write_field(dest, &wp, mi_len, 8);  // Mobile Identity length
+	bitvec_set_bytes(dest, mi, mi_len);        // Mobile Identity
+	wp += mi_len * 8;
 
 	if ((wp % 8))
 		log_alert_exit("Length of PAG.REQ without rest octets is not "

src/encoding.h

@@ -77,7 +77,7 @@ public:
 			bitvec * dest, struct gprs_rlcmac_ul_tbf *tbf, bool is_final,
 			uint8_t rrbp);
 
-	static int write_paging_request(bitvec * dest, uint8_t *ptmsi, uint16_t ptmsi_len);
+	static int write_paging_request(bitvec * dest, const uint8_t *mi, uint8_t mi_len);
 
 	static unsigned write_repeated_page_info(bitvec * dest, unsigned& wp, uint8_t len,
 			uint8_t *identity, uint8_t chan_needed);

src/gprs_bssgp_pcu.cpp

@@ -175,25 +175,18 @@ static int gprs_bssgp_pcu_rx_paging_ps(struct msgb *msg, struct tlv_parsed *tp)
 {
 	char imsi[16];
 	uint16_t pgroup;
-	uint8_t *ptmsi = (uint8_t *) TLVP_VAL(tp, BSSGP_IE_TMSI);
-	uint16_t ptmsi_len = TLVP_LEN(tp, BSSGP_IE_TMSI);
+	const uint8_t *mi;
+	uint8_t mi_len;
 	int rc;
 
-	LOGP(DBSSGP, LOGL_NOTICE, " P-TMSI = ");
-	for (int i = 0; i < ptmsi_len; i++)
-	{
-		LOGPC(DBSSGP, LOGL_NOTICE, "%02x", ptmsi[i]);
-	}
-	LOGPC(DBSSGP, LOGL_NOTICE, "\n");
-
 	if (!TLVP_PRESENT(tp, BSSGP_IE_IMSI)) {
 		LOGP(DBSSGP, LOGL_ERROR, "No IMSI\n");
-		return -EINVAL;
+		return bssgp_tx_status(BSSGP_CAUSE_MISSING_MAND_IE, NULL, msg);
 	}
 
 	/* gsm48_mi_to_string() returns number of bytes written, including '\0' */
 	rc = gsm48_mi_to_string(imsi, sizeof(imsi), TLVP_VAL(tp, BSSGP_IE_IMSI),
-						    TLVP_LEN(tp, BSSGP_IE_IMSI));
+				TLVP_LEN(tp, BSSGP_IE_IMSI));
 	if (rc != GSM23003_IMSI_MAX_DIGITS + 1) {
 		LOGP(DBSSGP, LOGL_NOTICE, "Failed to parse IMSI IE (rc=%d)\n", rc);
 		return bssgp_tx_status(BSSGP_CAUSE_INV_MAND_INF, NULL, msg);
@@ -204,7 +197,15 @@ static int gprs_bssgp_pcu_rx_paging_ps(struct msgb *msg, struct tlv_parsed *tp)
 		return bssgp_tx_status(BSSGP_CAUSE_INV_MAND_INF, NULL, msg);
 	}
 
-	return gprs_rlcmac_paging_request(ptmsi, ptmsi_len, pgroup);
+	if (TLVP_PRESENT(tp, BSSGP_IE_TMSI)) {
+		mi_len = TLVP_LEN(tp, BSSGP_IE_TMSI);
+		mi = TLVP_VAL(tp, BSSGP_IE_TMSI);
+	} else { /* Use IMSI if TMSI not available: */
+		mi_len = TLVP_LEN(tp, BSSGP_IE_IMSI);
+		mi = TLVP_VAL(tp, BSSGP_IE_IMSI);
+	}
+
+	return gprs_rlcmac_paging_request(mi, mi_len, pgroup);
 }
 
 /* Receive a BSSGP PDU from a BSS on a PTP BVCI */

src/gprs_rlcmac.cpp

@@ -19,6 +19,10 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  */
 
+extern "C" {
+	#include <osmocom/gsm/gsm48.h>
+}
+
 #include <pcu_l1_if.h>
 #include <gprs_rlcmac.h>
 #include <bts.h>
@@ -28,13 +32,13 @@
 
 extern void *tall_pcu_ctx;
 
-int gprs_rlcmac_paging_request(uint8_t *ptmsi, uint16_t ptmsi_len,
-			       uint16_t pgroup)
+int gprs_rlcmac_paging_request(const uint8_t *mi, uint8_t mi_len, uint16_t pgroup)
 {
-	LOGP(DRLCMAC, LOGL_NOTICE, "TX: [PCU -> BTS] Paging Request (CCCH)\n");
+	LOGP(DRLCMAC, LOGL_NOTICE, "TX: [PCU -> BTS] Paging Request (CCCH) MI=%s\n",
+	    osmo_mi_name(mi, mi_len));
 	bitvec *paging_request = bitvec_alloc(22, tall_pcu_ctx);
 	bitvec_unhex(paging_request, DUMMY_VEC);
-	int plen = Encoding::write_paging_request(paging_request, ptmsi, ptmsi_len);
+	int plen = Encoding::write_paging_request(paging_request, mi, mi_len);
 	pcu_l1if_tx_pch(paging_request, plen, pgroup);
 	bitvec_free(paging_request);
 

src/gprs_rlcmac.h

@@ -93,7 +93,7 @@ enum gprs_rlcmac_block_type {
 
 int gprs_rlcmac_tx_ul_ud(gprs_rlcmac_tbf *tbf);
 
-int gprs_rlcmac_paging_request(uint8_t *ptmsi, uint16_t ptmsi_len, uint16_t pgroup);
+int gprs_rlcmac_paging_request(const uint8_t *mi, uint8_t mi_len, uint16_t pgroup);
 
 struct msgb *gprs_rlcmac_app_info_msg(const struct gsm_pcu_if_app_info_req *req);