implement support for 3-digit MNC with leading zeros

Enable representing three-digit MNC with leading zeros. The MNCs 23 and 023 are
actually different; so far we treated both as 23. Re-encode an incoming BCD or
string of 023 as it were, i.e. not dropping the leading zero as 23.

Break ABI compatibility by changing the size and ordering of structs
gprs_ra_id, osmo_plmn_id, osmo_cell_global_id, ... by adding an mnc_3_digits
flag.

Change ordering in gprs_ra_id because the canonical oder is {Mobile Country
Code, Mobile Network Code}, so have the mcc member first.

ABI compatibility cannot be maintained for struct gprs_ra_id, since it is a
direct member of structs bssgp_bvc_ctx and bssgp_paging_info, and even just
adding a flag to the end would cause ABI changes of those structs. Similarly,
osmo_plmn_id is a direct member of osmo_location_area_id, and so forth.

Add new API to set and read this additional flag to preserve leading zeros:
- osmo_plmn_to_bcd(), osmo_plmn_from_bcd() after
  gsm48_mcc_mnc_to_bcd() and gsm48_mcc_mnc_from_bcd().
- gsm48_decode_lai2(), gsm48_generate_lai2() after
  gsm48_decode_lai(), gsm48_generate_lai().
- gsm0808_create_layer3_2() after gsm0808_create_layer3() and gsm0808_create_layer3_aoip().
- various osmo_*_name() functions in gsm23003.h (osmo_rai_name() still in
  gsm48.h close to struct gprs_ra_id definition). The amount and duplication of
  these may seem a bit overboard, but IMO they do make sense in this way.
  Though most code will soon see patches unifying the data structures used, in
  some cases (vty, ctrl) they are required singled out. Without these
  functions, the formatting ("%0*u", mnc_3_digits ?  3 : 2, mnc) would be
  duplicated all over our diverse repositories.

In various log output, include the leading MNC zeros.

Mark one TODO in card_fs_sim.c, I am not sure how to communicate a leading zero
to/from a SIM card FS. The focus here is on the core network / BSS.

To indicate ABI incompatibility, bump libosmogsm and libosmogb LIBVERSIONs;
adjust debian files accordingly.

Implementation choices:

- The default behavior upon zero-initialization will be the mnc_3_digits flag
  set to false, which yields exactly the previous behavior.

- I decided against packing the mnc with the mnc_3_digits field into a
  sub-struct because it would immediately break all builds of dependent
  projects: it would require immediate merging of numerous patches in other
  repositories, and it would make compiling older code against a newer
  libosmocore unneccessarily hard.

Change-Id: Id2240f7f518494c9df6c8bda52c0d5092f90f221

3 files changed, 23 insertions, 1 deletions

diff --git a/include/osmocom/gsm/gsm0808.h b/include/osmocom/gsm/gsm0808.h
index 3deee70d..8c276f58 100644
--- a/include/osmocom/gsm/gsm0808.h
+++ b/include/osmocom/gsm/gsm0808.h
@@ -25,6 +25,8 @@
 
 #include "tlv.h"
 #include <osmocom/gsm/protocol/gsm_08_08.h>
+#include <osmocom/gsm/gsm23003.h>
+
 struct sockaddr_storage;
 
 struct msgb;
@@ -35,6 +37,8 @@ struct msgb *gsm0808_create_layer3_aoip(const struct msgb *msg_l3, uint16_t nc,
 					uint16_t cc, int lac, uint16_t _ci,
 					const struct gsm0808_speech_codec_list
 					*scl);
+struct msgb *gsm0808_create_layer3_2(const struct msgb *msg_l3, const struct osmo_cell_global_id *cell,
+				     const struct gsm0808_speech_codec_list *scl);
 struct msgb *gsm0808_create_reset(void);
 struct msgb *gsm0808_create_reset_ack(void);
 struct msgb *gsm0808_create_clear_command(uint8_t reason);
diff --git a/include/osmocom/gsm/gsm23003.h b/include/osmocom/gsm/gsm23003.h
index dd41bc5b..51e5ef83 100644
--- a/include/osmocom/gsm/gsm23003.h
+++ b/include/osmocom/gsm/gsm23003.h
@@ -9,6 +9,7 @@
 struct osmo_plmn_id {
 	uint16_t mcc;
 	uint16_t mnc;
+	bool mnc_3_digits; /*< ignored and implied true if mnc > 99, otherwise defines leading zeros. */
 };
 
 /* 4.1 */
@@ -85,3 +86,12 @@ struct osmo_guti {
 
 bool osmo_imsi_str_valid(const char *imsi);
 bool osmo_msisdn_str_valid(const char *msisdn);
+
+const char *osmo_mcc_name(uint16_t mcc);
+const char *osmo_mnc_name(uint16_t mnc, bool mnc_3_digits);
+const char *osmo_plmn_name(const struct osmo_plmn_id *plmn);
+const char *osmo_plmn_name2(const struct osmo_plmn_id *plmn);
+const char *osmo_lai_name(const struct osmo_location_area_id *lai);
+
+void osmo_plmn_to_bcd(uint8_t *bcd_dst, const struct osmo_plmn_id *plmn);
+void osmo_plmn_from_bcd(const uint8_t *bcd_src, struct osmo_plmn_id *plmn);
diff --git a/include/osmocom/gsm/gsm48.h b/include/osmocom/gsm/gsm48.h
index 9ec54639..5f144358 100644
--- a/include/osmocom/gsm/gsm48.h
+++ b/include/osmocom/gsm/gsm48.h
@@ -2,17 +2,21 @@
 
 #pragma once
 
+#include <stdbool.h>
+
 #include <osmocom/gsm/tlv.h>
 #include <osmocom/gsm/protocol/gsm_04_08.h>
 #include <osmocom/gsm/gsm48_ie.h>
+#include <osmocom/gsm/gsm23003.h>
 
 /* reserved according to GSM 03.03 § 2.4 */
 #define GSM_RESERVED_TMSI   0xFFFFFFFF
 
 /* A parsed GPRS routing area */
 struct gprs_ra_id {
-	uint16_t	mnc;
 	uint16_t	mcc;
+	uint16_t	mnc;
+	bool		mnc_3_digits;
 	uint16_t	lac;
 	uint8_t		rac;
 };
@@ -24,11 +28,15 @@ const char *gsm48_cc_state_name(uint8_t state);
 const char *gsm48_cc_msg_name(uint8_t msgtype);
 const char *gsm48_rr_msg_name(uint8_t msgtype);
 const char *rr_cause_name(uint8_t cause);
+const char *osmo_rai_name(const struct gprs_ra_id *rai);
 
 int gsm48_decode_lai(struct gsm48_loc_area_id *lai, uint16_t *mcc,
 		     uint16_t *mnc, uint16_t *lac);
+void gsm48_decode_lai2(const struct gsm48_loc_area_id *lai, struct osmo_location_area_id *decoded);
 void gsm48_generate_lai(struct gsm48_loc_area_id *lai48, uint16_t mcc,
 			uint16_t mnc, uint16_t lac);
+void gsm48_generate_lai2(struct gsm48_loc_area_id *lai48, const struct osmo_location_area_id *lai);
+
 int gsm48_generate_mid_from_tmsi(uint8_t *buf, uint32_t tmsi);
 int gsm48_generate_mid_from_imsi(uint8_t *buf, const char *imsi);
 uint8_t gsm48_generate_mid(uint8_t *buf, const char *id, uint8_t mi_type);