add a regression test for TLV parsing with repeated IEs

Since commit bf383a1d83661af26ccd6521c49b655fb22531d4 tlv_parse()
will return the first occurrence of a repeated IE. Add a test to
verify this behaviour. This test passes with the current code and
fails if bf383a1d83661af26ccd6521c49b655fb22531d4 is reverted.

While here, fix lies in documentation about the return value of tlv_parse()
and fix a typo in another comment.

Change-Id: I041f38548c5e4236920991d6c681c1c1e04de9ca
Related: OS#2904

2 files changed, 33 insertions, 2 deletions

diff --git a/src/gsm/tlv_parser.c b/src/gsm/tlv_parser.c
index b8c7149f..f6939713 100644
--- a/src/gsm/tlv_parser.c
+++ b/src/gsm/tlv_parser.c
@@ -48,7 +48,7 @@
 struct tlv_definition tvlv_att_def;
 struct tlv_definition vtvlv_gan_att_def;
 
-/*! Dump pasred TLV structure to stdout */
+/*! Dump parsed TLV structure to stdout */
 int tlv_dump(struct tlv_parsed *dec)
 {
 	int i;
@@ -227,7 +227,7 @@ tlv:		/* GSM TS 04.07 11.2.4: Type 4 TLV */
  *  \param[in] buf_len length of the input data buffer
  *  \param[in] lv_tag an initial LV tag at the start of the buffer
  *  \param[in] lv_tag2 a second initial LV tag following the \a lv_tag
- *  \returns number of bytes consumed by the TLV entry / IE parsed; negative in case of error
+ *  \returns number of TLV entries parsed; negative in case of error
  */
 int tlv_parse(struct tlv_parsed *dec, const struct tlv_definition *def,
 	      const uint8_t *buf, int buf_len, uint8_t lv_tag,
diff --git a/tests/tlv/tlv_test.c b/tests/tlv/tlv_test.c
index 87b002f0..2e28e548 100644
--- a/tests/tlv/tlv_test.c
+++ b/tests/tlv/tlv_test.c
@@ -245,11 +245,42 @@ static void test_tlv_shift_functions()
 	}
 }
 
+/* Most GSM related protocols clearly indicate that in case of duplicate
+ * IEs, only the first occurrence shall be used, while any further occurrences
+ * shall be ignored.  See e.g. 3GPP TS 24.008 Section 8.6.3 */
+static void test_tlv_repeated_ie()
+{
+	uint8_t test_data[768];
+	int i, rc;
+	const uint8_t tag = 0x1a;
+	struct tlv_parsed dec;
+	struct tlv_definition def;
+
+	memset(&def, 0, sizeof(def));
+
+	/* tag:1:255, tag:1:254, tag:1:253, ..., tag:1:3, tag:1:2, tag:1:1, tag:1:0 */
+	for (i = 0; i < ARRAY_SIZE(test_data) - 1; i += 3) {
+		test_data[i] = tag;
+		test_data[i + 1] = 1;
+		test_data[i + 2] = (uint8_t)(0xff - i/2);
+	}
+
+	def.def[tag].type = TLV_TYPE_TLV;
+
+	rc = tlv_parse(&dec, &def, &test_data[1], sizeof(test_data) - 1, tag, 0);
+	OSMO_ASSERT(rc == i/3);
+	OSMO_ASSERT(dec.lv[tag].len == 1);
+	/* Value pointer should point at first value in test data array. */
+	OSMO_ASSERT(dec.lv[tag].val == &test_data[2]);
+	OSMO_ASSERT(*dec.lv[tag].val == test_data[2]);
+}
+
 int main(int argc, char **argv)
 {
 	//osmo_init_logging(&info);
 
 	test_tlv_shift_functions();
+	test_tlv_repeated_ie();
 
 	printf("Done.\n");
 	return EXIT_SUCCESS;