Add multiplexer

common/mux/protocol.go

@@ -0,0 +1,119 @@
+package mux
+
+import (
+	"encoding/binary"
+	"io"
+
+	C "github.com/sagernet/sing-box/constant"
+	"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"
+	N "github.com/sagernet/sing/common/network"
+	"github.com/sagernet/sing/common/rw"
+
+	"github.com/hashicorp/yamux"
+)
+
+var Destination = M.Socksaddr{
+	Fqdn: "sp.mux.sing-box.arpa",
+	Port: 444,
+}
+
+func newMuxConfig() *yamux.Config {
+	config := yamux.DefaultConfig()
+	config.LogOutput = io.Discard
+	config.StreamCloseTimeout = C.TCPTimeout
+	config.StreamOpenTimeout = C.TCPTimeout
+	return config
+}
+
+const (
+	version0      = 0
+	flagUDP       = 1
+	flagAddr      = 2
+	statusSuccess = 0
+	statusError   = 1
+)
+
+type Request struct {
+	Network     string
+	Destination M.Socksaddr
+	PacketAddr  bool
+}
+
+func ReadRequest(reader io.Reader) (*Request, error) {
+	version, err := rw.ReadByte(reader)
+	if err != nil {
+		return nil, err
+	}
+	if version != version0 {
+		return nil, E.New("unsupported version: ", version)
+	}
+	var flags uint16
+	err = binary.Read(reader, binary.BigEndian, &flags)
+	if err != nil {
+		return nil, err
+	}
+	destination, err := M.SocksaddrSerializer.ReadAddrPort(reader)
+	if err != nil {
+		return nil, err
+	}
+	var network string
+	var udpAddr bool
+	if flags&flagUDP == 0 {
+		network = N.NetworkTCP
+	} else {
+		network = N.NetworkUDP
+		udpAddr = flags&flagAddr != 0
+	}
+	return &Request{network, destination, udpAddr}, nil
+}
+
+func requestLen(request Request) int {
+	var rLen int
+	rLen += 1 // version
+	rLen += 2 // flags
+	rLen += M.SocksaddrSerializer.AddrPortLen(request.Destination)
+	return rLen
+}
+
+func EncodeRequest(request Request, buffer *buf.Buffer) {
+	destination := request.Destination
+	var flags uint16
+	if request.Network == N.NetworkUDP {
+		flags |= flagUDP
+	}
+	if request.PacketAddr {
+		flags |= flagAddr
+		if !destination.IsValid() {
+			destination = Destination
+		}
+	}
+	common.Must(
+		buffer.WriteByte(version0),
+		binary.Write(buffer, binary.BigEndian, flags),
+		M.SocksaddrSerializer.WriteAddrPort(buffer, destination),
+	)
+}
+
+type Response struct {
+	Status  uint8
+	Message string
+}
+
+func ReadResponse(reader io.Reader) (*Response, error) {
+	var response Response
+	status, err := rw.ReadByte(reader)
+	if err != nil {
+		return nil, err
+	}
+	response.Status = status
+	if status == statusError {
+		response.Message, err = rw.ReadVString(reader)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return &response, nil
+}