gsm48: add compare function for struct gprs_ra_id

Comparing struct gprs_ra_id using memcmp can be error prone, so lets add
a compare function to compare two struct gprs_ra_id values reliably.

Change-Id: I4d7558c04d9d01761516526086be5104bb2eeada
Related: SYS#5103

include/osmocom/gsm/gsm48.h

@@ -104,6 +104,7 @@ int osmo_mobile_identity_encode_msgb(struct msgb *msg, const struct osmo_mobile_
 void gsm48_parse_ra(struct gprs_ra_id *raid, const uint8_t *buf);
 void gsm48_encode_ra(struct gsm48_ra_id *out, const struct gprs_ra_id *raid);
 int gsm48_construct_ra(uint8_t *buf, const struct gprs_ra_id *raid) OSMO_DEPRECATED("Use gsm48_encode_ra() instead");
+bool gsm48_ra_equal(const struct gprs_ra_id *raid1, const struct gprs_ra_id *raid2);
 
 int gsm48_number_of_paging_subchannels(struct gsm48_control_channel_descr *chan_desc);
 

src/gsm/gsm48.c

@@ -1298,6 +1298,25 @@ int gsm48_construct_ra(uint8_t *buf, const struct gprs_ra_id *raid)
 	return 6;
 }
 
+/*! Compare a TS 04.08 Routing Area Identifier
+ *  \param[in] raid1 first Routing Area ID to compare.
+ *  \param[in] raid2 second Routing Area ID to compare.
+ *  \returns true if raid1 and raid2 match, false otherwise. */
+bool gsm48_ra_equal(const struct gprs_ra_id *raid1, const struct gprs_ra_id *raid2)
+{
+	if (raid1->mcc != raid2->mcc)
+		return false;
+	if (raid1->mnc != raid2->mnc)
+		return false;
+	if (raid1->mnc_3_digits != raid2->mnc_3_digits)
+		return false;
+	if (raid1->lac != raid2->lac)
+		return false;
+	if (raid1->rac != raid2->rac)
+		return false;
+	return true;
+}
+
 /*! Determine number of paging sub-channels
  *  \param[in] chan_desc Control Channel Description
  *  \returns number of paging sub-channels

src/gsm/libosmogsm.map

@@ -326,6 +326,7 @@ osmo_gsm48_rest_octets_si4_decode;
 gsm48_rr_msg_name;
 gsm48_cc_state_name;
 gsm48_construct_ra;
+gsm48_ra_equal;
 gsm48_encode_ra;
 gsm48_hdr_gmm_cipherable;
 gsm48_decode_bcd_number;