support for more cell ID list types in libosmocore

Introduce gsm0808_dec_cell_id_list2() with supports additional types of
cell identifier lists. The new parsing routines are based on similar
routines used by the paging code in osmo-bsc's osmo_bsc_bssap.c.

Likewise, introduce gsm0808_enc_cell_id_list2() with support for the
same additional types of cell identifier lists.

The old API using struct gsm0808_cell_id_list is deprecated.
The previous definition was insufficient because it assumed that all
decoded cell ID types could be represented with a single uint16_t.
It was declared in a GSM protocol header (gsm/protocol/gsm_08_08.h)
despite being a host-side representation of data in an IE.
The only user I am aware of is in osmo-msc, where this struct is used
for one local variable. osmo-msc releases >= 1.1.0 make use of this API.

While here, fix a small bug in a test:
test_gsm0808_enc_dec_cell_id_list_bss() set the cell ID type to 'LAC'
but obviously wants to use type 'BSS'.

Change-Id: Ib7e754f538df0c83298a3c958b4e15a32fcb8abb
Related: OS#2847

4 files changed, 46 insertions, 4 deletions

diff --git a/include/osmocom/gsm/gsm0808.h b/include/osmocom/gsm/gsm0808.h
index 8c276f58..9153d99f 100644
--- a/include/osmocom/gsm/gsm0808.h
+++ b/include/osmocom/gsm/gsm0808.h
@@ -30,6 +30,7 @@
 struct sockaddr_storage;
 
 struct msgb;
+struct gsm0808_cell_id_list2;
 
 struct msgb *gsm0808_create_layer3(struct msgb *msg_l3, uint16_t nc,
 				   uint16_t cc, int lac, uint16_t _ci);
@@ -70,9 +71,13 @@ struct msgb *gsm0808_create_ass_fail(uint8_t cause, const uint8_t *rr_cause,
 				     *scl);
 struct msgb *gsm0808_create_assignment_failure(uint8_t cause, uint8_t *rr_cause);
 struct msgb *gsm0808_create_clear_rqst(uint8_t cause);
+struct msgb *gsm0808_create_paging2(const char *imsi, const uint32_t *tmsi,
+				   const struct gsm0808_cell_id_list2 *cil,
+				   const uint8_t *chan_needed);
 struct msgb *gsm0808_create_paging(const char *imsi, const uint32_t *tmsi,
 				   const struct gsm0808_cell_id_list *cil,
-				   const uint8_t *chan_needed);
+				   const uint8_t *chan_needed)
+				   OSMO_DEPRECATED("use gsm0808_create_paging2 instead");
 
 struct msgb *gsm0808_create_dtap(struct msgb *msg, uint8_t link_id);
 void gsm0808_prepend_dtap_header(struct msgb *msg, uint8_t link_id);
diff --git a/include/osmocom/gsm/gsm0808_utils.h b/include/osmocom/gsm/gsm0808_utils.h
index 7432164d..363fc390 100644
--- a/include/osmocom/gsm/gsm0808_utils.h
+++ b/include/osmocom/gsm/gsm0808_utils.h
@@ -26,6 +26,27 @@
 struct sockaddr_storage;
 
 #include <osmocom/gsm/protocol/gsm_08_08.h>
+#include <osmocom/gsm/gsm23003.h>
+
+ /*! (225-1)/2 is the maximum number of elements in a cell identifier list. */
+#define GSM0808_CELL_ID_LIST2_MAXLEN		127
+
+/*! Parsed representation of a cell identifier list IE. */
+struct gsm0808_cell_id_list2 {
+	enum CELL_IDENT id_discr;
+	union {
+		/*!
+		 * All elements of these arrays contain parsed representations of the
+		 * data in the corresponding IE, in host-byte order.
+		 */
+		struct osmo_cell_global_id		global;
+		struct osmo_lac_and_ci_id		lac_and_ci;
+		uint16_t				ci;
+		struct osmo_location_area_id		lai_and_lac;
+		uint16_t				lac;
+	} id_list[GSM0808_CELL_ID_LIST2_MAXLEN];
+	unsigned int id_list_len;
+};
 
 uint8_t gsm0808_enc_aoip_trasp_addr(struct msgb *msg,
 				    const struct sockaddr_storage *ss);
@@ -48,10 +69,14 @@ uint8_t gsm0808_enc_encrypt_info(struct msgb *msg,
 				 const struct gsm0808_encrypt_info *ei);
 int gsm0808_dec_encrypt_info(struct gsm0808_encrypt_info *ei,
 			     const uint8_t *elem, uint8_t len);
+uint8_t gsm0808_enc_cell_id_list2(struct msgb *msg, const struct gsm0808_cell_id_list2 *cil);
 uint8_t gsm0808_enc_cell_id_list(struct msgb *msg,
-				 const struct gsm0808_cell_id_list *cil);
+				 const struct gsm0808_cell_id_list *cil)
+				 OSMO_DEPRECATED("use gsm0808_enc_cell_id_list2 instead");
+int gsm0808_dec_cell_id_list2(struct gsm0808_cell_id_list2 *cil, const uint8_t *elem, uint8_t len);
 int gsm0808_dec_cell_id_list(struct gsm0808_cell_id_list *cil,
-			     const uint8_t *elem, uint8_t len);
+			     const uint8_t *elem, uint8_t len)
+			     OSMO_DEPRECATED("use gsm0808_dec_cell_id_list2 instead");
 int gsm0808_chan_type_to_speech_codec(uint8_t perm_spch);
 int gsm0808_speech_codec_from_chan_type(struct gsm0808_speech_codec *sc,
 					uint8_t perm_spch);
diff --git a/include/osmocom/gsm/gsm23003.h b/include/osmocom/gsm/gsm23003.h
index 5d1fbd7f..02e79714 100644
--- a/include/osmocom/gsm/gsm23003.h
+++ b/include/osmocom/gsm/gsm23003.h
@@ -30,6 +30,13 @@ struct osmo_cell_global_id {
 	uint16_t cell_identity;
 };
 
+/* Actually defined in 3GPP TS 48.008 3.2.2.27 Cell Identifier List,
+ * but conceptually belongs with the above structures. */
+struct osmo_lac_and_ci_id {
+	uint16_t lac;
+	uint16_t ci;
+};
+
 /* 12.5 */
 struct osmo_service_area_id {
 	struct osmo_location_area_id lai;
diff --git a/include/osmocom/gsm/protocol/gsm_08_08.h b/include/osmocom/gsm/protocol/gsm_08_08.h
index ba347eff..947f90f2 100644
--- a/include/osmocom/gsm/protocol/gsm_08_08.h
+++ b/include/osmocom/gsm/protocol/gsm_08_08.h
@@ -501,8 +501,13 @@ struct gsm0808_encrypt_info {
 	unsigned int key_len;
 };
 
-/* 3GPP TS 48.008 3.2.2.27 Cell Identifier List */
 #define CELL_ID_LIST_LAC_MAXLEN 127
+/*!
+ * DEPRECATED: This definition of the cell identifier list is
+ * insufficient. It cannot support all types of cell identifiers.
+ * Use struct gsm0808_cell_id_list2 in gsm0808_utils.h instead.
+ *
+ * 3GPP TS 48.008 3.2.2.27 Cell Identifier List */
 struct gsm0808_cell_id_list {
 	uint8_t id_discr;
 	uint16_t id_list_lac[CELL_ID_LIST_LAC_MAXLEN];