streaming

commit 353e0a6999febb7e25924ca1e5f6893ea05ab3a9
parent cb4ee3fe5170849010abd352c327f6a7eaa5441f
Author: Oliver Lowe <o@olowe.co>
Date:   Thu, 25 Jul 2024 11:20:57 +1000

sdp: store m-line type as an int

Media types have 6 valid values defined in the RFC, so using our own
int is a bit clearer for users of the package (including me!) and can
catch out normal typos like "vvideo" - or really any other invalid
string.

Diffstat:
M
sdp/sdp.go
 | 
61
++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
M
sdp/sdp_test.go
 | 
6
+++---

2 files changed, 59 insertions(+), 8 deletions(-)
diff --git a/sdp/sdp.go b/sdp/sdp.go
@@ -157,9 +157,9 @@ func parseBandwidth(s string) (Bandwidth, error) {
 
 // Media represents a media description.
 type Media struct {
-	Type      string // TODO(otl): new type mediaType?
-	Port      int    // IP port
-	PortCount int    // count of subsequent ports from Port
+	Type      MediaType
+	Port      int // IP port
+	PortCount int // count of subsequent ports from Port
 	Transport TransportProto
 	// Format describes the media format. Interpretation of the
 	// entries depends on the value of Transport. For example, if
@@ -199,6 +199,53 @@ func (m Media) String() string {
 	return strings.TrimSpace(buf.String())
 }
 
+type MediaType uint8
+
+const (
+	MediaTypeAudio MediaType = iota
+	MediaTypeVideo
+	MediaTypeText
+	MediaTypeApplication
+	MediaTypeMessage
+	MediaTypeImage
+)
+
+func (t MediaType) String() string {
+	switch t {
+	case MediaTypeAudio:
+		return "audio"
+	case MediaTypeVideo:
+		return "video"
+	case MediaTypeText:
+		return "text"
+	case MediaTypeApplication:
+		return "application"
+	case MediaTypeMessage:
+		return "message"
+	case MediaTypeImage:
+		return "image"
+	}
+	return "unknown"
+}
+
+func parseMediaType(s string) (MediaType, error) {
+	switch s {
+	case MediaTypeAudio.String():
+		return MediaTypeAudio, nil
+	case MediaTypeVideo.String():
+		return MediaTypeVideo, nil
+	case MediaTypeText.String():
+		return MediaTypeText, nil
+	case MediaTypeApplication.String():
+		return MediaTypeApplication, nil
+	case MediaTypeMessage.String():
+		return MediaTypeMessage, nil
+	case MediaTypeImage.String():
+		return MediaTypeImage, nil
+	}
+	return 0, fmt.Errorf("unknown media type %s", s)
+}
+
 type TransportProto uint8
 
 const (
@@ -227,10 +274,14 @@ func parseMedia(s string) (Media, error) {
 	if len(fields) < 4 {
 		return Media{}, fmt.Errorf("found %d fields, need at least %d", len(fields), 4)
 	}
-	m := Media{Type: fields[0]}
+
+	mtyp, err := parseMediaType(fields[0])
+	if err != nil {
+		return Media{}, fmt.Errorf("media type: %w", err)
+	}
+	m := Media{Type: mtyp}
 
 	p, n, found := strings.Cut(fields[1], "/")
-	var err error
 	m.Port, err = strconv.Atoi(p)
 	if err != nil {
 		return Media{}, fmt.Errorf("parse port: %w", err)
diff --git a/sdp/sdp_test.go b/sdp/sdp_test.go
@@ -37,19 +37,19 @@ func TestReadSession(t *testing.T) {
 				},
 				Media: []Media{
 					Media{
-						Type:      "audio",
+						Type:      MediaTypeAudio,
 						Port:      49170,
 						Transport: ProtoRTP,
 						Format:    []string{"0"},
 					},
 					Media{
-						Type:      "audio",
+						Type:      MediaTypeAudio,
 						Port:      49180,
 						Transport: ProtoRTP,
 						Format:    []string{"0"},
 					},
 					Media{
-						Type:       "video",
+						Type:       MediaTypeVideo,
 						Port:       51372,
 						Transport:  ProtoRTP,
 						Format:     []string{"99"},