add gsm0808_{enc,dec}_cell_id

Clarify semantics and micro-optimise for the case of single Cell Identifer IEs.
Test in gsm0808_test.c

So far we have gsm0808_enc_cell_id_list2(), but there also exist instances of
single Cell Identifiers (3GPP TS 48.008 3.2.2.17).

It is possible to decode the same using the cell identifier list API, but this
forces the caller to also keep a full struct gsm0808_cell_id_list2 with all its
127 entries around.

E.g. for handover, there are two Cell Identifiers (Serving and Target); I'd
need two full cell id lists for each, and these would be dynamically allocated
for each handover operation, whether it uses them or not.

Related: OS#2283 (inter-BSC HO, BSC side)
Change-Id: I9f9c528965775698ab62ac386af0516192c4b0cc

2 files changed, 206 insertions, 0 deletions

diff --git a/tests/gsm0808/gsm0808_test.c b/tests/gsm0808/gsm0808_test.c
index f4670996..8c184dda 100644
--- a/tests/gsm0808/gsm0808_test.c
+++ b/tests/gsm0808/gsm0808_test.c
@@ -1256,6 +1256,196 @@ void test_cell_id_list_add() {
 	printf("------- %s done\n", __func__);
 }
 
+#define EXPECT_ENCODED(hexstr) do { \
+		const char *enc_str = msgb_hexdump(msg); \
+		printf("%s: encoded: %s(rc = %u)\n", __func__, enc_str, rc_enc); \
+		OSMO_ASSERT(strcmp(enc_str, hexstr " ") == 0); \
+		OSMO_ASSERT(rc_enc == msg->len); \
+	} while(0)
+
+static void test_gsm0808_enc_dec_cell_id_lac()
+{
+	struct gsm0808_cell_id enc_ci = {
+		.id_discr = CELL_IDENT_LAC,
+		.id.lac = 0x0124,
+	};
+	struct gsm0808_cell_id dec_ci;
+	struct msgb *msg;
+	uint8_t rc_enc;
+	int rc_dec;
+
+	memset(&dec_ci, 0xa5, sizeof(dec_ci));
+
+	msg = msgb_alloc(1024, "output buffer");
+	rc_enc = gsm0808_enc_cell_id(msg, &enc_ci);
+	EXPECT_ENCODED("05 03 05 01 24");
+
+	rc_dec = gsm0808_dec_cell_id(&dec_ci, msg->data + 2, msg->len - 2);
+	OSMO_ASSERT(rc_dec == 3);
+
+	OSMO_ASSERT(enc_ci.id_discr == dec_ci.id_discr
+		    && enc_ci.id.lac == dec_ci.id.lac);
+
+	msgb_free(msg);
+}
+
+static void test_gsm0808_enc_dec_cell_id_bss()
+{
+	struct gsm0808_cell_id enc_ci = {
+		.id_discr = CELL_IDENT_BSS,
+	};
+	struct gsm0808_cell_id dec_ci;
+	struct msgb *msg;
+	uint8_t rc_enc;
+	int rc_dec;
+
+	msg = msgb_alloc(1024, "output buffer");
+	rc_enc = gsm0808_enc_cell_id(msg, &enc_ci);
+	EXPECT_ENCODED("05 01 06");
+
+	rc_dec = gsm0808_dec_cell_id(&dec_ci, msg->data + 2, msg->len - 2);
+	OSMO_ASSERT(rc_dec == 1);
+
+	OSMO_ASSERT(enc_ci.id_discr == dec_ci.id_discr);
+
+	msgb_free(msg);
+}
+
+static void test_gsm0808_enc_dec_cell_id_no_cell()
+{
+	struct gsm0808_cell_id enc_ci = {
+		.id_discr = CELL_IDENT_NO_CELL,
+	};
+	struct gsm0808_cell_id dec_ci;
+	struct msgb *msg;
+	uint8_t rc_enc;
+	int rc_dec;
+
+	msg = msgb_alloc(1024, "output buffer");
+	rc_enc = gsm0808_enc_cell_id(msg, &enc_ci);
+	EXPECT_ENCODED("05 01 03");
+
+	rc_dec = gsm0808_dec_cell_id(&dec_ci, msg->data + 2, msg->len - 2);
+	OSMO_ASSERT(rc_dec == 1);
+
+	OSMO_ASSERT(enc_ci.id_discr == dec_ci.id_discr);
+
+	msgb_free(msg);
+}
+
+static void test_gsm0808_enc_dec_cell_id_lai_and_lac()
+{
+	struct gsm0808_cell_id enc_ci = {
+		.id_discr = CELL_IDENT_LAI_AND_LAC,
+		.id.lai_and_lac = {
+			.plmn = {
+				.mcc = 123,
+				.mnc = 456,
+			},
+			.lac = 0x2342,
+		},
+	};
+	struct gsm0808_cell_id dec_ci;
+	struct msgb *msg;
+	uint8_t rc_enc;
+	int rc_dec;
+
+	msg = msgb_alloc(1024, "output buffer");
+	rc_enc = gsm0808_enc_cell_id(msg, &enc_ci);
+	EXPECT_ENCODED("05 06 04 21 63 54 23 42");
+
+	memset(&dec_ci, 0xa5, sizeof(dec_ci));
+	rc_dec = gsm0808_dec_cell_id(&dec_ci, msg->data + 2, msg->len - 2);
+	OSMO_ASSERT(rc_dec == msg->len - 2);
+
+	OSMO_ASSERT(enc_ci.id_discr == dec_ci.id_discr
+		    && osmo_plmn_cmp(&enc_ci.id.lai_and_lac.plmn, &dec_ci.id.lai_and_lac.plmn) == 0
+		    && enc_ci.id.lai_and_lac.lac == dec_ci.id.lai_and_lac.lac);
+	msgb_free(msg);
+}
+
+static void test_gsm0808_enc_dec_cell_id_ci()
+{
+	struct gsm0808_cell_id enc_ci = {
+		.id_discr = CELL_IDENT_CI,
+		.id.ci = 0x423,
+	};
+	struct gsm0808_cell_id dec_ci;
+	struct msgb *msg;
+	uint8_t rc_enc;
+	int rc_dec;
+
+	msg = msgb_alloc(1024, "output buffer");
+	rc_enc = gsm0808_enc_cell_id(msg, &enc_ci);
+	EXPECT_ENCODED("05 03 02 04 23");
+
+	rc_dec = gsm0808_dec_cell_id(&dec_ci, msg->data + 2, msg->len - 2);
+	OSMO_ASSERT(rc_dec == msg->len - 2);
+	OSMO_ASSERT(enc_ci.id_discr == dec_ci.id_discr
+		    && enc_ci.id.ci == dec_ci.id.ci);
+
+	msgb_free(msg);
+}
+
+static void test_gsm0808_enc_dec_cell_id_lac_and_ci()
+{
+	struct gsm0808_cell_id enc_ci = {
+		.id_discr = CELL_IDENT_LAC_AND_CI,
+		.id.lac_and_ci = {
+			.lac = 0x423,
+			.ci = 0x235,
+		},
+	};
+	struct gsm0808_cell_id dec_ci;
+	struct msgb *msg;
+	uint8_t rc_enc;
+	int rc_dec;
+
+	msg = msgb_alloc(1024, "output buffer");
+	rc_enc = gsm0808_enc_cell_id(msg, &enc_ci);
+	EXPECT_ENCODED("05 05 01 04 23 02 35");
+
+	rc_dec = gsm0808_dec_cell_id(&dec_ci, msg->data + 2, msg->len - 2);
+	OSMO_ASSERT(rc_dec == msg->len - 2);
+	OSMO_ASSERT(enc_ci.id_discr == dec_ci.id_discr
+		    && enc_ci.id.lac_and_ci.lac == dec_ci.id.lac_and_ci.lac
+		    && enc_ci.id.lac_and_ci.ci == dec_ci.id.lac_and_ci.ci);
+
+	msgb_free(msg);
+}
+
+static void test_gsm0808_enc_dec_cell_id_global()
+{
+	struct gsm0808_cell_id enc_ci = {
+		.id_discr = CELL_IDENT_WHOLE_GLOBAL,
+		.id.global = {
+			.lai = {
+				.plmn = { .mcc = 123, .mnc = 456 },
+				.lac = 0x2342
+			},
+			.cell_identity = 0x423,
+		}
+	};
+	struct gsm0808_cell_id dec_ci;
+	struct msgb *msg;
+	uint8_t rc_enc;
+	int rc_dec;
+
+	msg = msgb_alloc(1024, "output buffer");
+	rc_enc = gsm0808_enc_cell_id(msg, &enc_ci);
+	EXPECT_ENCODED("05 08 00 21 63 54 23 42 04 23");
+
+	rc_dec = gsm0808_dec_cell_id(&dec_ci, msg->data + 2, msg->len - 2);
+	OSMO_ASSERT(rc_dec == msg->len - 2);
+
+	OSMO_ASSERT(enc_ci.id_discr == dec_ci.id_discr
+		    && osmo_plmn_cmp(&enc_ci.id.global.lai.plmn,
+				     &dec_ci.id.global.lai.plmn) == 0
+		    && enc_ci.id.global.lai.lac == dec_ci.id.global.lai.lac
+		    && enc_ci.id.global.cell_identity == dec_ci.id.global.cell_identity);
+	msgb_free(msg);
+}
+
 int main(int argc, char **argv)
 {
 	printf("Testing generation of GSM0808 messages\n");
@@ -1287,6 +1477,7 @@ int main(int argc, char **argv)
 	test_gsm0808_enc_dec_speech_codec_list();
 	test_gsm0808_enc_dec_channel_type();
 	test_gsm0808_enc_dec_encrypt_info();
+
 	test_gsm0808_enc_dec_cell_id_list_lac();
 	test_gsm0808_enc_dec_cell_id_list_single_lac();
 	test_gsm0808_enc_dec_cell_id_list_multi_lac();
@@ -1298,6 +1489,14 @@ int main(int argc, char **argv)
 
 	test_cell_id_list_add();
 
+	test_gsm0808_enc_dec_cell_id_lac();
+	test_gsm0808_enc_dec_cell_id_bss();
+	test_gsm0808_enc_dec_cell_id_no_cell();
+	test_gsm0808_enc_dec_cell_id_lai_and_lac();
+	test_gsm0808_enc_dec_cell_id_ci();
+	test_gsm0808_enc_dec_cell_id_lac_and_ci();
+	test_gsm0808_enc_dec_cell_id_global();
+
 	printf("Done\n");
 	return EXIT_SUCCESS;
 }
diff --git a/tests/gsm0808/gsm0808_test.ok b/tests/gsm0808/gsm0808_test.ok
index a049dec5..27170f27 100644
--- a/tests/gsm0808/gsm0808_test.ok
+++ b/tests/gsm0808/gsm0808_test.ok
@@ -104,4 +104,11 @@ cil.id_list_len = 127
 gsm0808_cell_id_list_add(&cil, &cgi2a) --> rc = -28
 cil.id_list_len = 127
 ------- test_cell_id_list_add done
+test_gsm0808_enc_dec_cell_id_lac: encoded: 05 03 05 01 24 (rc = 5)
+test_gsm0808_enc_dec_cell_id_bss: encoded: 05 01 06 (rc = 3)
+test_gsm0808_enc_dec_cell_id_no_cell: encoded: 05 01 03 (rc = 3)
+test_gsm0808_enc_dec_cell_id_lai_and_lac: encoded: 05 06 04 21 63 54 23 42 (rc = 8)
+test_gsm0808_enc_dec_cell_id_ci: encoded: 05 03 02 04 23 (rc = 5)
+test_gsm0808_enc_dec_cell_id_lac_and_ci: encoded: 05 05 01 04 23 02 35 (rc = 7)
+test_gsm0808_enc_dec_cell_id_global: encoded: 05 08 00 21 63 54 23 42 04 23 (rc = 10)
 Done