Use capsulate protocol for large UDP packet

- make datagram transport without mux functionality
- it is now recommended to always pair with mux-cool (XUDP new tunnel non-zero session id)

transport/internet/quic/conn.go

@@ -6,22 +6,83 @@ import (
 
 	"github.com/quic-go/quic-go"
 	"github.com/xtls/xray-core/common/buf"
+	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
+	"github.com/xtls/xray-core/common/signal/done"
 )
 
+var MaxIncomingStreams = 2
+var currentStream = 0
+
 type interConn struct {
-	ctx      context.Context
-	quicConn quic.Connection
-	local    net.Addr
-	remote   net.Addr
+	ctx         context.Context
+	quicConn    quic.Connection // small udp packet can be sent with Datagram directly 
+	streams     []quic.Stream	// other packets can be sent via steam, it offer mux, reliability, fragmentation and ordering 
+	readChannel chan readResult
+	done        *done.Instance
+	local       net.Addr
+	remote      net.Addr
 }
 
-func (c *interConn) Read(b []byte) (int, error) {
-	received, e := c.quicConn.ReceiveDatagram(c.ctx)
-	if e != nil {
-		return 0, e
+type readResult struct {
+	buffer []byte
+	err    error 
+}
+
+func NewConnInitReader(ctx context.Context, quicConn quic.Connection, done *done.Instance, remote net.Addr) *interConn {
+	c := &interConn{
+		ctx:         ctx,
+		quicConn:    quicConn,
+		readChannel: make(chan readResult),
+		done:        done,
+		local:       quicConn.LocalAddr(),
+		remote:      remote,
 	}
-	nBytes := copy(b, received[:])
+	go func() {
+		for {
+			received, e := c.quicConn.ReceiveDatagram(c.ctx)
+			c.readChannel <- readResult{buffer: received, err: e}
+		}
+	}()
+	go c.acceptStreams()
+	return c
+}
+
+func (c *interConn) acceptStreams() {
+	for {
+		stream, err := c.quicConn.AcceptStream(context.Background())
+		if err != nil {
+			errors.LogInfoInner(context.Background(), err, "failed to accept stream")
+			select {
+			case <-c.quicConn.Context().Done():
+				return
+			case <-c.done.Wait():
+				if err := c.quicConn.CloseWithError(0, ""); err != nil {
+					errors.LogInfoInner(context.Background(), err, "failed to close connection")
+				}
+				return
+			default:
+				time.Sleep(time.Second)
+				continue
+			}
+		}
+		go func() {
+			for {
+				received := make([]byte, buf.Size)
+				i, e := stream.Read(received)
+				c.readChannel <- readResult{buffer: received[:i], err: e}
+			}
+		}()
+		c.streams = append(c.streams, stream)
+	}
+}
+
+func (c *interConn) Read(b []byte) (int, error) {	
+	received := <- c.readChannel
+	if received.err != nil {
+		return 0, received.err
+	}
+	nBytes := copy(b, received.buffer[:])
 	return nBytes, nil
 }
 
@@ -33,11 +94,37 @@ func (c *interConn) WriteMultiBuffer(mb buf.MultiBuffer) error {
 }
 
 func (c *interConn) Write(b []byte) (int, error) {
-	return len(b), c.quicConn.SendDatagram(b)
+	var err = c.quicConn.SendDatagram(b)
+	if _, ok := err.(*quic.DatagramTooLargeError); ok {
+		if len(c.streams) < MaxIncomingStreams {
+			stream, err := c.quicConn.OpenStream()
+			if err == nil {
+				c.streams = append(c.streams, stream)
+			} else {
+				errors.LogInfoInner(c.ctx, err, "failed to openStream: ")
+			}
+		}
+		currentStream++;
+		if currentStream > len(c.streams) - 1 {
+			currentStream = 0;
+		}
+		return c.streams[currentStream].Write(b)
+	}
+	if err != nil {
+		return 0, err
+	}
+	return len(b), nil
 }
 
 func (c *interConn) Close() error {
-	return nil
+	var err error
+	for _, s := range c.streams {
+		e := s.Close()
+		if e != nil {
+			err = e
+		}
+	}
+	return err
 }
 
 func (c *interConn) LocalAddr() net.Addr {
@@ -49,13 +136,34 @@ func (c *interConn) RemoteAddr() net.Addr {
 }
 
 func (c *interConn) SetDeadline(t time.Time) error {
-	return nil
+	var err error
+	for _, s := range c.streams {
+		e := s.SetDeadline(t)
+		if e != nil {
+			err = e
+		}
+	}
+	return err
 }
 
 func (c *interConn) SetReadDeadline(t time.Time) error {
-	return nil
+	var err error
+	for _, s := range c.streams {
+		e := s.SetReadDeadline(t)
+		if e != nil {
+			err = e
+		}
+	}
+	return err
 }
 
 func (c *interConn) SetWriteDeadline(t time.Time) error {
-	return nil
+	var err error
+	for _, s := range c.streams {
+		e := s.SetWriteDeadline(t)
+		if e != nil {
+			err = e
+		}
+	}
+	return err
 }

transport/internet/quic/dialer.go

@@ -2,38 +2,18 @@ package quic
 
 import (
 	"context"
-	"sync"
 	"time"
 
 	"github.com/quic-go/quic-go"
 	"github.com/xtls/xray-core/common"
 	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
+	"github.com/xtls/xray-core/common/signal/done"
 	"github.com/xtls/xray-core/transport/internet"
 	"github.com/xtls/xray-core/transport/internet/stat"
 	"github.com/xtls/xray-core/transport/internet/tls"
 )
 
-type connectionContext struct {
-	rawConn *net.UDPConn
-	conn    quic.Connection
-}
-
-type clientConnections struct {
-	access  sync.Mutex
-	conns   map[net.Destination][]*connectionContext
-	// cleanup *task.Periodic
-}
-
-func isActive(s quic.Connection) bool {
-	select {
-	case <-s.Context().Done():
-		return false
-	default:
-		return true
-	}
-}
-
 func Dial(ctx context.Context, dest net.Destination, streamSettings *internet.MemoryStreamConfig) (stat.Connection, error) {
 	tlsConfig := tls.ConfigFromStreamSettings(streamSettings)
 	if tlsConfig == nil {
@@ -68,38 +48,11 @@ func Dial(ctx context.Context, dest net.Destination, streamSettings *internet.Me
 
 	config := streamSettings.ProtocolSettings.(*Config)
 
-	return client.openConnection(ctx, destAddr, config, tlsConfig, streamSettings.SocketSettings)
+	return openConnection(ctx, destAddr, config, tlsConfig, streamSettings.SocketSettings)
 }
 
-func (s *clientConnections) openConnection(ctx context.Context, destAddr net.Addr, config *Config, tlsConfig *tls.Config, sockopt *internet.SocketConfig) (stat.Connection, error) {
-	s.access.Lock()
-	defer s.access.Unlock()
-
-	if s.conns == nil {
-		s.conns = make(map[net.Destination][]*connectionContext)
-	}
-
+func openConnection(ctx context.Context, destAddr net.Addr, config *Config, tlsConfig *tls.Config, sockopt *internet.SocketConfig) (stat.Connection, error) {
 	dest := net.DestinationFromAddr(destAddr)
-
-	var conns []*connectionContext
-	if s, found := s.conns[dest]; found {
-		conns = s
-	}
-
-	if len(conns) > 0 {
-		s := conns[len(conns)-1]
-		if isActive(s.conn) {
-			return 	&interConn{
-				ctx: ctx,
-				quicConn: s.conn,
-				local:  s.conn.LocalAddr(),
-				remote: destAddr,
-			}, nil
-		} else {
-			errors.LogInfo(ctx, "current quic connection is not active!")
-		}
-	}
-
 	errors.LogInfo(ctx, "dialing quic to ", dest)
 	rawConn, err := internet.DialSystem(ctx, dest, sockopt)
 	if err != nil {
@@ -134,21 +87,9 @@ func (s *clientConnections) openConnection(ctx context.Context, destAddr net.Add
 		return nil, err
 	}
 
-	context := &connectionContext{
-		conn:    conn,
-		rawConn: udpConn,
-	}
-	s.conns[dest] = append(conns, context)
-	return &interConn{
-		ctx: ctx,
-		quicConn: context.conn,
-		local:  context.conn.LocalAddr(),
-		remote: destAddr,
-	}, nil
+	return NewConnInitReader(ctx, conn, done.New(), destAddr), nil
 }
 
-var client clientConnections
-
 func init() {
 	common.Must(internet.RegisterTransportDialer(protocolName, Dial))
 }

transport/internet/quic/hub.go

@@ -33,12 +33,7 @@ func (l *Listener) keepAccepting(ctx context.Context) {
 			time.Sleep(time.Second)
 			continue
 		}
-		l.addConn(&interConn{
-			ctx: ctx,
-			quicConn: conn,
-			local:  conn.LocalAddr(),
-			remote: conn.RemoteAddr(),
-		})
+		l.addConn(NewConnInitReader(ctx, conn, l.done, conn.RemoteAddr()))
 	}
 }
 
@@ -81,7 +76,7 @@ func Listen(ctx context.Context, address net.Address, port net.Port, streamSetti
 		KeepAlivePeriod:       0,
 		HandshakeIdleTimeout:  time.Second * 8,
 		MaxIdleTimeout:        time.Second * 300,
-		MaxIncomingStreams:    32,
+		MaxIncomingStreams:    2,
 		MaxIncomingUniStreams: -1,
 		EnableDatagrams:       true,
 	}

transport/internet/quic/quic_test.go

@@ -18,7 +18,15 @@ import (
 	"github.com/xtls/xray-core/transport/internet/tls"
 )
 
-func TestQuicConnection(t *testing.T) {
+func TestShortQuicConnection(t *testing.T) {
+	testQuicConnection(t, 1024)
+}
+
+func TestLongQuicConnection(t *testing.T) {
+	testQuicConnection(t, 1500)
+}
+
+func testQuicConnection(t *testing.T, dataLen int32) {
 	port := udp.PickPort()
 
 	listener, err := quic.Listen(context.Background(), net.LocalHostIP, port, &internet.MemoryStreamConfig{
@@ -69,15 +77,14 @@ func TestQuicConnection(t *testing.T) {
 	common.Must(err)
 	defer conn.Close()
 
-	const N = 1024
-	b1 := make([]byte, N)
+	b1 := make([]byte, dataLen)
 	common.Must2(rand.Read(b1))
 	b2 := buf.New()
 
 	common.Must2(conn.Write(b1))
 
 	b2.Clear()
-	common.Must2(b2.ReadFullFrom(conn, N))
+	common.Must2(b2.ReadFullFrom(conn, dataLen))
 	if r := cmp.Diff(b2.Bytes(), b1); r != "" {
 		t.Error(r)
 	}
@@ -85,7 +92,7 @@ func TestQuicConnection(t *testing.T) {
 	common.Must2(conn.Write(b1))
 
 	b2.Clear()
-	common.Must2(b2.ReadFullFrom(conn, N))
+	common.Must2(b2.ReadFullFrom(conn, dataLen))
 	if r := cmp.Diff(b2.Bytes(), b1); r != "" {
 		t.Error(r)
 	}