support encrypted streams with SRTP and MIKEY (#520) (#809)

pkg/mikey/payload_t.go

@@ -0,0 +1,56 @@
+package mikey
+
+import "fmt"
+
+// PayloadT is a timestamp payload.
+type PayloadT struct {
+	TSType  uint8
+	TSValue uint64
+}
+
+func (p *PayloadT) unmarshal(buf []byte) (int, error) {
+	if len(buf) < 10 {
+		return 0, fmt.Errorf("buffer too short")
+	}
+
+	n := 1
+	p.TSType = buf[n]
+	n++
+
+	if p.TSType != 0 {
+		return 0, fmt.Errorf("unsupported TSType: %v", p.TSType)
+	}
+
+	p.TSValue = uint64(buf[n])<<56 |
+		uint64(buf[n+1])<<48 |
+		uint64(buf[n+2])<<40 |
+		uint64(buf[n+3])<<32 |
+		uint64(buf[n+4])<<24 |
+		uint64(buf[n+5])<<16 |
+		uint64(buf[n+6])<<8 |
+		uint64(buf[n+7])
+	n += 8
+
+	return n, nil
+}
+
+func (*PayloadT) typ() payloadType {
+	return payloadTypeT
+}
+
+func (p *PayloadT) marshalSize() int {
+	return 10
+}
+
+func (p *PayloadT) marshalTo(buf []byte) (int, error) {
+	buf[1] = p.TSType
+	buf[2] = byte(p.TSValue >> 56)
+	buf[3] = byte(p.TSValue >> 48)
+	buf[4] = byte(p.TSValue >> 40)
+	buf[5] = byte(p.TSValue >> 32)
+	buf[6] = byte(p.TSValue >> 24)
+	buf[7] = byte(p.TSValue >> 16)
+	buf[8] = byte(p.TSValue >> 8)
+	buf[9] = byte(p.TSValue)
+	return 10, nil
+}