Implement pending queue in mux for dropped packets

internal/mux/mux.go

@@ -9,6 +9,7 @@
 	"io"
 	"net"
 	"sync"
+	"time"
 
 	"github.com/pion/ice/v3"
 	"github.com/pion/logging"
@@ -34,20 +35,25 @@
 	bufferSize int
 	closedCh   chan struct{}
 
+	pendingPackets     map[*pendingPacket]struct{}
+	pendingPacketsLock sync.Mutex
+
 	log logging.LeveledLogger
 }
 
 // NewMux creates a new Mux
 func NewMux(config Config) *Mux {
 	m := &Mux{
-		nextConn:   config.Conn,
-		endpoints:  make(map[*Endpoint]MatchFunc),
-		bufferSize: config.BufferSize,
-		closedCh:   make(chan struct{}),
-		log:        config.LoggerFactory.NewLogger("mux"),
+		nextConn:       config.Conn,
+		endpoints:      make(map[*Endpoint]MatchFunc),
+		bufferSize:     config.BufferSize,
+		closedCh:       make(chan struct{}),
+		log:            config.LoggerFactory.NewLogger("mux"),
+		pendingPackets: make(map[*pendingPacket]struct{}),
 	}
 
 	go m.readLoop()
+	go m.pendingPacketsHandler()
 
 	return m
 }
@@ -140,10 +146,17 @@
 
 	if endpoint == nil {
 		if len(buf) > 0 {
-			m.log.Warnf("Warning: mux: no endpoint for packet starting with %d", buf[0])
+			m.log.Warnf("Warning: mux: no endpoint for packet starting with %d, queueing packet as pending", buf[0])
 		} else {
-			m.log.Warnf("Warning: mux: no endpoint for zero length packet")
+			m.log.Warnf("Warning: mux: no endpoint for zero length packet, queueing packet as pending")
 		}
+
+		m.pendingPacketsLock.Lock()
+		m.pendingPackets[&pendingPacket{
+			t:    time.Now(),
+			data: buf,
+		}] = struct{}{}
+		m.pendingPacketsLock.Unlock()
 		return nil
 	}
 
@@ -157,3 +170,38 @@
 
 	return err
 }
+
+func (m *Mux) pendingPacketsHandler() {
+	ticker := time.NewTicker(time.Millisecond)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			m.lock.RLock()
+			m.pendingPacketsLock.Lock()
+			for p := range m.pendingPackets {
+				if time.Since(p.t) > time.Second*5 {
+					m.log.Warnf("Warning: mux: dropping packet after 5 seconds in pending queue")
+					delete(m.pendingPackets, p)
+				}
+				for endpoint, f := range m.endpoints {
+					if f(p.data) {
+						_, _ = endpoint.buffer.Write(p.data)
+						delete(m.pendingPackets, p)
+						m.log.Warnf("Warning: mux: found endpoint for packet after %s in pending queue", time.Since(p.t))
+					}
+				}
+			}
+			m.pendingPacketsLock.Unlock()
+			m.lock.RUnlock()
+		case <-m.closedCh:
+			return
+		}
+	}
+}
+
+type pendingPacket struct {
+	t    time.Time
+	data []byte
+}