mgcp_codec: do not differentiate between oa and bwe when comparing codec

AMR that has the payload format bandwith-efficient is the same codec as
AMR that has the payload format octet-aligned. Its the same codec, and a
comparison of the codec info with the function codecs_same() should
return true (=equal).

The affected function codecs_same() is used by mgcp_codec_pt_translate().
When the egress payload type number is looked up, the ingress and egress
codec information is compared. When one end is using AMR in
bandwith-efficient format and the other end is using it in
octet-alingned format. Then the codec still must be recognized as the
same codec. Othersiwse the payload type number translation would not
work, even though the codec is the same on both sides.

Change-Id: I64731570c287a75d39c79c10e1bc09a37bdd54d6
Related: SYS#5834

include/osmocom/mgcp/mgcp_codec.h

@@ -17,3 +17,4 @@ int mgcp_codec_decide(struct mgcp_conn_rtp *conn);
 int mgcp_codec_pt_translate(struct mgcp_conn_rtp *conn_src, struct mgcp_conn_rtp *conn_dst, int payload_type);
 const struct mgcp_rtp_codec *mgcp_codec_pt_find_by_subtype_name(struct mgcp_conn_rtp *conn,
 								const char *subtype_name, unsigned int match_nr);
+bool mgcp_codec_amr_is_octet_aligned(const struct mgcp_rtp_codec *codec);

src/libosmo-mgcp/mgcp_codec.c

@@ -355,7 +355,7 @@ int mgcp_codec_decide(struct mgcp_conn_rtp *conn)
  *
  * https://tools.ietf.org/html/rfc4867
  */
-static bool amr_is_octet_aligned(const struct mgcp_rtp_codec *codec)
+bool mgcp_codec_amr_is_octet_aligned(const struct mgcp_rtp_codec *codec)
 {
 	if (!codec->param_present)
 		return false;
@@ -378,10 +378,10 @@ static bool codecs_same(struct mgcp_rtp_codec *codec_a, struct mgcp_rtp_codec *c
 		return false;
 	if (strcmp(codec_a->subtype_name, codec_b->subtype_name))
 		return false;
-	if (!strcmp(codec_a->subtype_name, "AMR")) {
-		if (amr_is_octet_aligned(codec_a) != amr_is_octet_aligned(codec_b))
-			return false;
-	}
+
+	/* Note: AMR allows to set the RTP payload format to octet-aligned or bandwith-efficient (octet-aligned=0)
+	 * via SDP. This difference concerns payload format only, but not the actual codec. It is not a difference
+	 * within the meaning of this function. */
 
 	return true;
 }

tests/mgcp/mgcp_test.c

@@ -1896,16 +1896,13 @@ static const struct testcase_mgcp_codec_pt_translate test_mgcp_codec_pt_translat
 		.codecs = {
 			{
 				{ 111, "AMR/8000", &amr_param_octet_aligned_true, },
-				{ 112, "AMR/8000", &amr_param_octet_aligned_false, },
 			},
 			{
 				{ 122, "AMR/8000", &amr_param_octet_aligned_false, },
-				{ 121, "AMR/8000", &amr_param_octet_aligned_true, },
 			},
 		},
 		.expect = {
-			{ .payload_type_map = {111, 121}, },
-			{ .payload_type_map = {112, 122} },
+			{ .payload_type_map = {111, 122}, },
 			{ .end = true },
 		},
 	},
@@ -1914,15 +1911,13 @@ static const struct testcase_mgcp_codec_pt_translate test_mgcp_codec_pt_translat
 		.codecs = {
 			{
 				{ 111, "AMR/8000", &amr_param_octet_aligned_true, },
-				{ 112, "AMR/8000", &amr_param_octet_aligned_false, },
 			},
 			{
 				{ 122, "AMR/8000", &amr_param_octet_aligned_unset, },
 			},
 		},
 		.expect = {
-			{ .payload_type_map = {111, -EINVAL}, },
-			{ .payload_type_map = {112, 122} },
+			{ .payload_type_map = {111, 122}, },
 			{ .end = true },
 		},
 	},
@@ -1931,15 +1926,13 @@ static const struct testcase_mgcp_codec_pt_translate test_mgcp_codec_pt_translat
 		.codecs = {
 			{
 				{ 111, "AMR/8000", &amr_param_octet_aligned_true, },
-				{ 112, "AMR/8000", &amr_param_octet_aligned_false, },
 			},
 			{
 				{ 122, "AMR/8000", NULL, },
 			},
 		},
 		.expect = {
-			{ .payload_type_map = {111, -EINVAL}, },
-			{ .payload_type_map = {112, 122} },
+			{ .payload_type_map = {111, 122}, },
 			{ .end = true },
 		},
 	},

tests/mgcp/mgcp_test.ok

@@ -1347,32 +1347,24 @@ Testing mgcp_codec_pt_translate()
  - mgcp_codec_pt_translate(conn0, conn1, 112) -> -22
  - mgcp_codec_pt_translate(conn0, conn1, 0) -> -22
  - mgcp_codec_pt_translate(conn0, conn1, 111) -> -22
-#4: conn1 has no codecs
 #4: conn1 has no codecs
  - add codecs on conn0:
-    1:   0 PCMU/8000/1  -> rc=0
-    2: 111 GSM-HR-08/8000/1  -> rc=0
- - add codecs on conn1:
-    (none)
- - mgcp_codec_pt_translate(conn0, conn1, 112) -> -22
+    0: 112 AMR/8000/1 octet-aligned=1  -> rc=0
+    1:   0 PCMU/8000/1  -> rc=0
     2: 111 GSM-HR-08/8000/1  -> rc=0
  - add codecs on conn1:
     (none)
- - add codecs on conn0:
  - mgcp_codec_pt_translate(conn0, conn1, 112) -> -22
  - mgcp_codec_pt_translate(conn0, conn1, 0) -> -22
- - add codecs on conn1:
-    0: 122 AMR/8000 octet-aligned=0  -> rc=0
-    1: 121 AMR/8000 octet-aligned=1  -> rc=0
+ - mgcp_codec_pt_translate(conn0, conn1, 111) -> -22
+#5: test AMR with differing octet-aligned settings
  - add codecs on conn0:
     0: 111 AMR/8000 octet-aligned=1  -> rc=0
  - add codecs on conn1:
- - mgcp_codec_pt_translate(conn1, conn0, 122) -> 112
     0: 122 AMR/8000 octet-aligned=0  -> rc=0
  - mgcp_codec_pt_translate(conn0, conn1, 111) -> 122
-    0: 111 AMR/8000 octet-aligned=1  -> rc=0
-    1: 112 AMR/8000 octet-aligned=0  -> rc=0
- - add codecs on conn1:
+ - mgcp_codec_pt_translate(conn1, conn0, 122) -> 111
+#6: test AMR with missing octet-aligned settings (defaults to 0)
  - add codecs on conn0:
     0: 111 AMR/8000 octet-aligned=1  -> rc=0
  - add codecs on conn1: