Fix concurrent map iteration for Track

pkg/streamer/track.go

@@ -3,6 +3,7 @@ package streamer
 import (
 	"fmt"
 	"github.com/pion/rtp"
+	"sync"
 )
 
 type WriterFunc func(packet *rtp.Packet) error
@@ -12,6 +13,7 @@ type Track struct {
 	Codec     *Codec
 	Direction string
 	Sink      map[*Track]WriterFunc
+	mx        sync.Mutex
 }
 
 func (t *Track) String() string {
@@ -21,9 +23,11 @@ func (t *Track) String() string {
 }
 
 func (t *Track) WriteRTP(p *rtp.Packet) error {
+	t.mx.Lock()
 	for _, f := range t.Sink {
 		_ = f(p)
 	}
+	t.mx.Unlock()
 	return nil
 }
 
@@ -35,10 +39,14 @@ func (t *Track) Bind(w WriterFunc) *Track {
 	clone := &Track{
 		Codec: t.Codec, Direction: t.Direction, Sink: t.Sink,
 	}
+	t.mx.Lock()
 	t.Sink[clone] = w
+	t.mx.Unlock()
 	return clone
 }
 
 func (t *Track) Unbind() {
+	t.mx.Lock()
 	delete(t.Sink, t)
+	t.mx.Unlock()
 }