From e679fa146e2d067885e2f75f19b1fb0d7b359b07 Mon Sep 17 00:00:00 2001
From: Neels Hofmeyr <nhofmeyr@sysmocom.de>
Date: Tue, 19 Jul 2022 12:16:02 +0200
Subject: [PATCH] sdp_msg.c: parse send/recv mode

Related: SYS#5066
Change-Id: I529c0bfad1cab376e26173ed48db2767c7dfaa64
---
 include/osmocom/msc/sdp_msg.h |  9 +++++++++
 src/libmsc/sdp_msg.c          | 31 ++++++++++++++++++++++---------
 tests/sdp_msg/sdp_msg_test.c  |  2 ++
 tests/sdp_msg/sdp_msg_test.ok |  2 ++
 4 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/include/osmocom/msc/sdp_msg.h b/include/osmocom/msc/sdp_msg.h
index cf1e56055..1b905b7ef 100644
--- a/include/osmocom/msc/sdp_msg.h
+++ b/include/osmocom/msc/sdp_msg.h
@@ -9,6 +9,14 @@ static inline const char *sdp_msg_payload_type_name(unsigned int payload_type)
 { return get_value_string(sdp_msg_payload_type_names, payload_type); }
 int sdp_subtype_name_to_payload_type(const char *subtype_name);
 
+enum sdp_mode_e {
+	SDP_MODE_UNSET = 0,
+	SDP_MODE_SENDONLY = 1,
+	SDP_MODE_RECVONLY = 2,
+	SDP_MODE_SENDRECV = 3,
+	SDP_MODE_INACTIVE = 4,
+};
+
 struct sdp_audio_codec {
 	/* Payload type number, like 3 for GSM-FR. */
 	unsigned int payload_type;
@@ -26,6 +34,7 @@ struct sdp_audio_codecs {
 struct sdp_msg {
 	struct osmo_sockaddr_str rtp;
 	unsigned int ptime;
+	enum sdp_mode_e mode;
 	struct sdp_audio_codecs audio_codecs;
 };
 
diff --git a/src/libmsc/sdp_msg.c b/src/libmsc/sdp_msg.c
index a76ae5e5f..dd5551769 100644
--- a/src/libmsc/sdp_msg.c
+++ b/src/libmsc/sdp_msg.c
@@ -227,6 +227,14 @@ int sdp_audio_codecs_remove(struct sdp_audio_codecs *ac, const struct sdp_audio_
 	return 0;
 }
 
+static const char *sdp_mode_str[] = {
+	[SDP_MODE_UNSET] = "-",
+	[SDP_MODE_SENDONLY] = "sendonly",
+	[SDP_MODE_RECVONLY] = "recvonly",
+	[SDP_MODE_SENDRECV] = "sendrecv",
+	[SDP_MODE_INACTIVE] = "inactive",
+};
+
 /* Convert struct sdp_msg to the actual SDP protocol representation */
 int sdp_msg_to_sdp_str_buf(char *dst, size_t dst_size, const struct sdp_msg *sdp)
 {
@@ -262,6 +270,9 @@ int sdp_msg_to_sdp_str_buf(char *dst, size_t dst_size, const struct sdp_msg *sdp
 
 	OSMO_STRBUF_PRINTF(sb, "a=ptime:%d\r\n", sdp->ptime > 0? sdp->ptime : 20);
 
+	if (sdp->mode != SDP_MODE_UNSET && sdp->mode < ARRAY_SIZE(sdp_mode_str))
+		OSMO_STRBUF_PRINTF(sb, "a=%s\r\n", sdp_mode_str[sdp->mode]);
+
 	return sb.chars_needed;
 }
 
@@ -287,9 +298,6 @@ int sdp_parse_attrib(struct sdp_msg *sdp, const char *src)
 #define A_FMTP "fmtp:"
 #define A_PTIME "ptime:"
 #define A_RTCP "rtcp:"
-#define A_SENDRECV "sendrecv"
-#define A_SENDONLY "sendonly"
-#define A_RECVONLY "recvonly"
 
 	if (osmo_str_startswith(src, A_RTPMAP)) {
 		/* "a=rtpmap:3 GSM/8000" */
@@ -346,19 +354,24 @@ int sdp_parse_attrib(struct sdp_msg *sdp, const char *src)
 		/* TODO? */
 	}
 
-	else if (osmo_str_startswith(src, A_SENDRECV)) {
+	else if (osmo_str_startswith(src, sdp_mode_str[SDP_MODE_SENDRECV])) {
 		/* "a=sendrecv" */
-		/* TODO? */
+		sdp->mode = SDP_MODE_SENDRECV;
 	}
 
-	else if (osmo_str_startswith(src, A_SENDONLY)) {
+	else if (osmo_str_startswith(src, sdp_mode_str[SDP_MODE_SENDONLY])) {
 		/* "a=sendonly" */
-		/* TODO? */
+		sdp->mode = SDP_MODE_SENDONLY;
 	}
 
-	else if (osmo_str_startswith(src, A_RECVONLY)) {
+	else if (osmo_str_startswith(src, sdp_mode_str[SDP_MODE_RECVONLY])) {
 		/* "a=recvonly" */
-		/* TODO? */
+		sdp->mode = SDP_MODE_RECVONLY;
+	}
+
+	else if (osmo_str_startswith(src, sdp_mode_str[SDP_MODE_INACTIVE])) {
+		/* "a=inactive" */
+		sdp->mode = SDP_MODE_INACTIVE;
 	}
 
 	return 0;
diff --git a/tests/sdp_msg/sdp_msg_test.c b/tests/sdp_msg/sdp_msg_test.c
index ee48e808f..a1ffac0f6 100644
--- a/tests/sdp_msg/sdp_msg_test.c
+++ b/tests/sdp_msg/sdp_msg_test.c
@@ -61,6 +61,7 @@ struct sdp_test_data sdp_tests[] = {
 		"a=rtpmap:101 telephone-event/8000\r\n"
 		"a=fmtp:101 0-15\r\n"
 		"a=ptime:20\r\n"
+		"a=sendrecv\r\n"
 		,
 	},
 	{
@@ -116,6 +117,7 @@ struct sdp_test_data sdp_tests[] = {
 		"a=rtpmap:101 telephone-event/8000\r\n"
 		"a=fmtp:101 0-15\r\n"
 		"a=ptime:20\r\n"
+		"a=sendrecv\r\n"
 		,
 	},
 };
diff --git a/tests/sdp_msg/sdp_msg_test.ok b/tests/sdp_msg/sdp_msg_test.ok
index 5f84ddd57..51a236b51 100644
--- a/tests/sdp_msg/sdp_msg_test.ok
+++ b/tests/sdp_msg/sdp_msg_test.ok
@@ -42,6 +42,7 @@ sdp_msg_to_sdp_str_buf: a=fmtp:100 192-193\r\n
 sdp_msg_to_sdp_str_buf: a=rtpmap:101 telephone-event/8000\r\n
 sdp_msg_to_sdp_str_buf: a=fmtp:101 0-15\r\n
 sdp_msg_to_sdp_str_buf: a=ptime:20\r\n
+sdp_msg_to_sdp_str_buf: a=sendrecv\r\n
 [0] ok
 
 [1]
@@ -95,6 +96,7 @@ sdp_msg_to_sdp_str_buf: a=rtpmap:8 PCMA/8000\r\n
 sdp_msg_to_sdp_str_buf: a=rtpmap:101 telephone-event/8000\r\n
 sdp_msg_to_sdp_str_buf: a=fmtp:101 0-15\r\n
 sdp_msg_to_sdp_str_buf: a=ptime:20\r\n
+sdp_msg_to_sdp_str_buf: a=sendrecv\r\n
 [2] ok