improve API for osmo_routing_area_id

Code review for [1] has asked for providing proper API for struct
osmo_routing_area_id.

For historical reasons, we have struct gprs_ra_id and
struct osmo_routing_area_id serving the exact same purpose: represent a
decoded 3GPP TS 24.008 § 10.5.5.15 Routing area identification.

The "better" one is struct osmo_routing_area_id: it allows using API
like osmo_plmn_cmp(), because it is made up of meaningful sub-structs.

Implement de/coding using the functions already available for the
sub-struct osmo_location_area_id, and simply add the RAC.

Add a test in gsm0408_test.c.

Note that other utility functions are already available for struct
osmo_routing_area_id: osmo_rai_name2(), osmo_rai_cmp().

There is no real need to deprecate struct gprs_ra_id, because there is
not really anything wrong with it. It just isn't as well integrated with
other utility API as struct osmo_routing_area_id is. Just add comments.

[1] osmo-hnbgw.git:
    cnpool: extract Mobile Identity from RANAP payload
    https://gerrit.osmocom.org/c/osmo-hnbgw/+/33133
    I373d665c9684b607207f68094188eab63209db51

Change-Id: Ic5e0406d9e20b0d4e1372fa30ba11a1e69f5cc94

1 files changed, 6 insertions, 1 deletions

diff --git a/include/osmocom/gsm/gsm48.h b/include/osmocom/gsm/gsm48.h
index 8323c724..00fb6f40 100644
--- a/include/osmocom/gsm/gsm48.h
+++ b/include/osmocom/gsm/gsm48.h
@@ -20,7 +20,9 @@
  * To mark an invalid / unset MNC, this value shall be used. */
 #define GSM_MCC_MNC_INVALID 0xFFFF
 
-/* A parsed GPRS routing area */
+/* A parsed GPRS routing area.
+ * Preferably use struct osmo_routing_area_id, it is better integrated with API like osmo_plmn_cmp().
+ */
 struct gprs_ra_id {
 	uint16_t	mcc;
 	uint16_t	mnc;
@@ -104,6 +106,9 @@ int osmo_mobile_identity_encode_buf(uint8_t *buf, size_t buflen, const struct os
 int osmo_mobile_identity_encode_msgb(struct msgb *msg, const struct osmo_mobile_identity *mi, bool allow_hex);
 
 /* Parse Routeing Area Identifier */
+int osmo_routing_area_id_decode(struct osmo_routing_area_id *dst, const uint8_t *ra_data, size_t ra_data_len);
+int osmo_routing_area_id_encode_buf(uint8_t *buf, size_t buflen, const struct osmo_routing_area_id *src);
+int osmo_routing_area_id_encode_msgb(struct msgb *msg, const struct osmo_routing_area_id *src);
 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");