fix parse_cell_id_lac_and_ci_list()

The implementation was entirely broken, reading data from wrong offsets
and always writing to the first element of the decoded list.

Also, add a new test for this function which found the problems.

Change-Id: If0fafbc7171da2a3044bfa9a167208a1afa1c07b
Related: OS#2847
Depends: Ife4e485e2b86c6f3321c9700611700115ad247b2

2 files changed, 49 insertions, 6 deletions

diff --git a/src/gsm/gsm0808_utils.c b/src/gsm/gsm0808_utils.c
index 0165e8af..b58a4b8a 100644
--- a/src/gsm/gsm0808_utils.c
+++ b/src/gsm/gsm0808_utils.c
@@ -719,7 +719,7 @@ static int parse_cell_id_lac_and_ci_list(struct gsm0808_cell_id_list2 *cil, cons
 {
 	uint16_t *lacp_be, *ci_be;
 	struct osmo_lac_and_ci_id *id;
-	int i = 0;
+	int i = 0, j = 0;
 	const size_t elemlen = sizeof(*lacp_be) + sizeof(*ci_be);
 
 	*consumed = 0;
@@ -727,18 +727,19 @@ static int parse_cell_id_lac_and_ci_list(struct gsm0808_cell_id_list2 *cil, cons
 	if (remain < elemlen)
 		return -EINVAL;
 
-	lacp_be = (uint16_t *)(&data[0]);
-	ci_be = (uint16_t *)(&data[2]);
+	lacp_be = (uint16_t *)(&data[j]);
+	ci_be = (uint16_t *)(&data[j + elemlen/2]);
 	while (remain >= elemlen) {
 		if (i >= GSM0808_CELL_ID_LIST2_MAXLEN)
 			return -ENOSPC;
-		id = &cil->id_list[i].lac_and_ci;
+		id = &cil->id_list[i++].lac_and_ci;
 		id->lac = osmo_load16be(lacp_be);
 		id->ci = osmo_load16be(ci_be);
 		*consumed += elemlen;
 		remain -= elemlen;
-		lacp_be++;
-		ci_be++;
+		j += elemlen;
+		lacp_be = (uint16_t *)(&data[j]);
+		ci_be = (uint16_t *)(&data[j + elemlen/2]);
 	}
 
 	return i;
diff --git a/tests/gsm0808/gsm0808_test.c b/tests/gsm0808/gsm0808_test.c
index 2ce4ab26..6a589a34 100644
--- a/tests/gsm0808/gsm0808_test.c
+++ b/tests/gsm0808/gsm0808_test.c
@@ -954,6 +954,47 @@ static void test_gsm0808_enc_dec_cell_id_list_multi_ci()
 	msgb_free(msg);
 }
 
+static void test_gsm0808_enc_dec_cell_id_list_multi_lac_and_ci()
+{
+	struct gsm0808_cell_id_list2 enc_cil;
+	struct gsm0808_cell_id_list2 dec_cil;
+	struct msgb *msg;
+	uint8_t cil_enc_expected[] = { GSM0808_IE_CELL_IDENTIFIER_LIST, 0x15, 0x01,
+		0x23, 0x42, 0x00, 0x01,
+		0x24, 0x43, 0x00, 0x02,
+		0x25, 0x44, 0x00, 0x77,
+		0x26, 0x45, 0x01, 0xff,
+		0x27, 0x46, 0x02, 0xfe,
+	};
+	uint8_t rc_enc;
+	int rc_dec;
+
+	memset(&enc_cil, 0, sizeof(enc_cil));
+	enc_cil.id_discr = CELL_IDENT_LAC_AND_CI;
+	enc_cil.id_list[0].lac_and_ci.lac = 0x2342;
+	enc_cil.id_list[0].lac_and_ci.ci = 1;
+	enc_cil.id_list[1].lac_and_ci.lac = 0x2443;
+	enc_cil.id_list[1].lac_and_ci.ci = 2;
+	enc_cil.id_list[2].lac_and_ci.lac = 0x2544;
+	enc_cil.id_list[2].lac_and_ci.ci = 119;
+	enc_cil.id_list[3].lac_and_ci.lac = 0x2645;
+	enc_cil.id_list[3].lac_and_ci.ci = 511;
+	enc_cil.id_list[4].lac_and_ci.lac = 0x2746;
+	enc_cil.id_list[4].lac_and_ci.ci = 766;
+	enc_cil.id_list_len = 5;
+
+	msg = msgb_alloc(1024, "output buffer");
+	rc_enc = gsm0808_enc_cell_id_list2(msg, &enc_cil);
+	OSMO_ASSERT(rc_enc == sizeof(cil_enc_expected));
+	OSMO_ASSERT(memcmp(cil_enc_expected, msg->data, msg->len) == 0);
+
+	rc_dec = gsm0808_dec_cell_id_list2(&dec_cil, msg->data + 2, msg->len - 2);
+	OSMO_ASSERT(rc_dec == msg->len - 2);
+	OSMO_ASSERT(memcmp(&enc_cil, &dec_cil, sizeof(enc_cil)) == 0);
+
+	msgb_free(msg);
+}
+
 int main(int argc, char **argv)
 {
 	printf("Testing generation of GSM0808 messages\n");
@@ -991,6 +1032,7 @@ int main(int argc, char **argv)
 	test_gsm0808_enc_dec_cell_id_list_bss();
 	test_gsm0808_enc_dec_cell_id_list_multi_lai_and_lac();
 	test_gsm0808_enc_dec_cell_id_list_multi_ci();
+	test_gsm0808_enc_dec_cell_id_list_multi_lac_and_ci();
 
 	printf("Done\n");
 	return EXIT_SUCCESS;