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 ยง 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
diff --git a/src/gsm/gsm48.c b/src/gsm/gsm48.c
index df455ac..53e0989 100644
--- a/src/gsm/gsm48.c
+++ b/src/gsm/gsm48.c
@@ -1334,7 +1334,64 @@
return 1;
}
-/*! Parse TS 04.08 Routing Area Identifier
+/*! Decode to struct osmo_routing_area_id from a 3GPP TS 24.008 § 10.5.5.15 Routing area identification.
+ * \param[out] dst Store the decoded result here.
+ * \param[in] ra_data The start of a Routing Area ID in encoded form, to be decoded.
+ * \param[in] ra_data_len Buffer size available to read from at *ra_data.
+ * \return the number of decoded bytes on success, or negative on error (if the input buffer is too small).
+ */
+int osmo_routing_area_id_decode(struct osmo_routing_area_id *dst, const uint8_t *ra_data, size_t ra_data_len)
+{
+ const struct gsm48_ra_id *ra_id;
+ if (ra_data_len < sizeof(*ra_id))
+ return -ENOSPC;
+
+ gsm48_decode_lai2((void *)ra_data, &dst->lac);
+
+ ra_id = (void *)ra_data;
+ dst->rac = ra_id->rac;
+
+ return sizeof(*ra_id);
+}
+
+/*! Encode struct osmo_routing_area_id to a 3GPP TS 24.008 § 10.5.5.15 Routing area identification: write to a buffer.
+ * \param[out] buf Return buffer for encoded Mobile Identity.
+ * \param[in] buflen sizeof(buf).
+ * \param[in] src RA to encode.
+ * \return Amount of bytes written to buf, or negative on error.
+ */
+int osmo_routing_area_id_encode_buf(uint8_t *buf, size_t buflen, const struct osmo_routing_area_id *src)
+{
+ struct gsm48_ra_id *ra_id;
+ if (buflen < sizeof(*ra_id))
+ return -ENOSPC;
+
+ gsm48_generate_lai2((void *)buf, &src->lac);
+
+ ra_id = (void *)buf;
+ ra_id->rac = src->rac;
+
+ return sizeof(*ra_id);
+}
+
+/*! Encode struct osmo_routing_area_id to a 3GPP TS 24.008 § 10.5.5.15 Routing area identification: append to msgb.
+ * To succeed, the msgb must have tailroom >= sizeof(struct gsm48_ra_id).
+ * \param[out] msg Append to this msgb.
+ * \param[in] src Encode this Routing Area ID.
+ * \return Number of bytes appended to msgb, or negative on error.
+ */
+int osmo_routing_area_id_encode_msgb(struct msgb *msg, const struct osmo_routing_area_id *src)
+{
+ int rc = osmo_routing_area_id_encode_buf(msg->tail, msgb_tailroom(msg), src);
+ if (rc <= 0)
+ return rc;
+ msgb_put(msg, rc);
+ return rc;
+}
+
+/*! Parse TS 04.08 Routing Area Identifier.
+ * Preferably use osmo_routing_area_id_decode() instead: struct osmo_routing_area_id is better integrated with other API
+ * like osmo_plmn_cmp().
* \param[out] Caller-provided memory for decoded RA ID
* \param[in] buf Input buffer pointing to RAI IE value */
void gsm48_parse_ra(struct gprs_ra_id *raid, const uint8_t *buf)
diff --git a/src/gsm/libosmogsm.map b/src/gsm/libosmogsm.map
index 0e45dc1..1eea819 100644
--- a/src/gsm/libosmogsm.map
+++ b/src/gsm/libosmogsm.map
@@ -415,6 +415,9 @@
osmo_mobile_identity_encoded_len;
osmo_mobile_identity_encode_buf;
osmo_mobile_identity_encode_msgb;
+osmo_routing_area_id_decode;
+osmo_routing_area_id_encode_buf;
+osmo_routing_area_id_encode_msgb;
gsm48_mm_att_tlvdef;
gsm48_number_of_paging_subchannels;
gsm48_parse_ra;