Update UoT protocol

common/low_memory.go

@@ -2,4 +2,4 @@
 
 package common
 
-const LowMemory = true
+const LowMemory = true

common/low_memory_stub.go

@@ -2,4 +2,4 @@
 
 package common
 
-const LowMemory = false
+const LowMemory = false

common/uot/client.go

@@ -0,0 +1,80 @@
+package uot
+
+import (
+	"context"
+	"net"
+
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+)
+
+type Client struct {
+	Dialer  N.Dialer
+	Version uint8
+}
+
+func (c *Client) DialConn(conn net.Conn, isConnect bool, destination M.Socksaddr) (*Conn, error) {
+	switch c.Version {
+	case 0, Version:
+		request := Request{
+			IsConnect:   isConnect,
+			Destination: destination,
+		}
+		err := WriteRequest(conn, request)
+		if err != nil {
+			return nil, err
+		}
+		return NewConn(conn, request), nil
+	case LegacyVersion:
+		return NewConn(conn, Request{}), nil
+	default:
+		return nil, E.New("unknown protocol version: ", c.Version)
+	}
+}
+
+func (c *Client) DialEarlyConn(conn net.Conn, isConnect bool, destination M.Socksaddr) (*Conn, error) {
+	switch c.Version {
+	case 0, Version:
+		request := Request{
+			IsConnect:   isConnect,
+			Destination: destination,
+		}
+		return NewLazyConn(conn, request), nil
+	case LegacyVersion:
+		return NewConn(conn, Request{}), nil
+	default:
+		return nil, E.New("unknown protocol version: ", c.Version)
+	}
+}
+
+func (c *Client) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
+	switch N.NetworkName(network) {
+	case N.NetworkUDP:
+		tcpConn, err := c.Dialer.DialContext(ctx, N.NetworkTCP, RequestDestination(c.Version))
+		if err != nil {
+			return nil, err
+		}
+		uConn, err := c.DialEarlyConn(tcpConn, true, destination)
+		if err != nil {
+			tcpConn.Close()
+			return nil, err
+		}
+		return uConn, nil
+	default:
+		return c.Dialer.DialContext(ctx, network, destination)
+	}
+}
+
+func (c *Client) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
+	tcpConn, err := c.Dialer.DialContext(ctx, N.NetworkTCP, RequestDestination(c.Version))
+	if err != nil {
+		return nil, err
+	}
+	uConn, err := c.DialEarlyConn(tcpConn, false, destination)
+	if err != nil {
+		tcpConn.Close()
+		return nil, err
+	}
+	return uConn, nil
+}

common/uot/conn.go

@@ -20,11 +20,11 @@ type Conn struct {
 	writer      N.VectorisedWriter
 }
 
-func NewConn(conn net.Conn, isConnect bool, destination M.Socksaddr) *Conn {
+func NewConn(conn net.Conn, request Request) *Conn {
 	uConn := &Conn{
 		Conn:        conn,
-		isConnect:   isConnect,
-		destination: destination,
+		isConnect:   request.IsConnect,
+		destination: request.Destination,
 	}
 	uConn.writer, _ = bufio.CreateVectorisedWriter(conn)
 	return uConn

common/uot/lazy.go

@@ -25,7 +25,7 @@ func NewLazyClientConn(conn net.Conn, request Request) *LazyClientConn {
 
 func NewLazyConn(conn net.Conn, request Request) *Conn {
 	clientConn := NewLazyClientConn(conn, request)
-	return NewConn(clientConn, request.IsConnect, request.Destination)
+	return NewConn(clientConn, request)
 }
 
 func (c *LazyClientConn) Write(p []byte) (n int, err error) {

common/uot/protocol.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/buf"
-	E "github.com/sagernet/sing/common/exceptions"
 	M "github.com/sagernet/sing/common/metadata"
 )
 
@@ -23,22 +22,25 @@ var AddrParser = M.NewSerializer(
 	M.AddressFamilyByte(0x02, M.AddressFamilyFqdn),
 )
 
+func RequestDestination(version uint8) M.Socksaddr {
+	switch version {
+	case 0, Version:
+		return M.Socksaddr{Fqdn: MagicAddress}
+	default:
+		fallthrough
+	case LegacyVersion:
+		return M.Socksaddr{Fqdn: LegacyMagicAddress}
+	}
+}
+
 type Request struct {
 	IsConnect   bool
 	Destination M.Socksaddr
 }
 
 func ReadRequest(reader io.Reader) (*Request, error) {
-	var version uint8
-	err := binary.Read(reader, binary.BigEndian, &version)
-	if err != nil {
-		return nil, err
-	}
-	if version != Version {
-		return nil, E.New("unsupported version: ", version)
-	}
 	var request Request
-	err = binary.Read(reader, binary.BigEndian, &request.IsConnect)
+	err := binary.Read(reader, binary.BigEndian, &request.IsConnect)
 	if err != nil {
 		return nil, err
 	}
@@ -51,12 +53,10 @@ func ReadRequest(reader io.Reader) (*Request, error) {
 
 func EncodeRequest(request Request) *buf.Buffer {
 	var bufferLen int
-	bufferLen += 1 // version
 	bufferLen += 1 // isConnect
 	bufferLen += M.SocksaddrSerializer.AddrPortLen(request.Destination)
 	buffer := buf.NewSize(bufferLen)
 	common.Must(
-		binary.Write(buffer, binary.BigEndian, uint8(Version)),
 		binary.Write(buffer, binary.BigEndian, request.IsConnect),
 		M.SocksaddrSerializer.WriteAddrPort(buffer, request.Destination),
 	)