Add gun-lite gRPC implementation (#44)

transport/v2raygrpclite/conn.go

@@ -0,0 +1,168 @@
+package v2raygrpclite
+
+import (
+	std_bufio "bufio"
+	"bytes"
+	"encoding/binary"
+	"io"
+	"net"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/sagernet/sing/common"
+	"github.com/sagernet/sing/common/buf"
+	"github.com/sagernet/sing/common/bufio"
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/rw"
+)
+
+// kanged from: https://github.com/Qv2ray/gun-lite
+
+var _ net.Conn = (*GunConn)(nil)
+
+type GunConn struct {
+	reader        *std_bufio.Reader
+	writer        io.Writer
+	flusher       http.Flusher
+	create        chan struct{}
+	err           error
+	readRemaining int
+}
+
+func newGunConn(reader io.Reader, writer io.Writer, flusher http.Flusher) *GunConn {
+	return &GunConn{
+		reader:  std_bufio.NewReader(reader),
+		writer:  writer,
+		flusher: flusher,
+	}
+}
+
+func newLateGunConn(writer io.Writer) *GunConn {
+	return &GunConn{
+		create: make(chan struct{}),
+		writer: writer,
+	}
+}
+
+func (c *GunConn) setup(reader io.Reader, err error) {
+	c.reader = std_bufio.NewReader(reader)
+	c.err = err
+	close(c.create)
+}
+
+func (c *GunConn) Read(b []byte) (n int, err error) {
+	n, err = c.read(b)
+	return n, wrapError(err)
+}
+
+func (c *GunConn) read(b []byte) (n int, err error) {
+	if c.reader == nil {
+		<-c.create
+		if c.err != nil {
+			return 0, c.err
+		}
+	}
+
+	if c.readRemaining > 0 {
+		if len(b) > c.readRemaining {
+			b = b[:c.readRemaining]
+		}
+		n, err = c.reader.Read(b)
+		c.readRemaining -= n
+		return
+	}
+
+	_, err = c.reader.Discard(6)
+	if err != nil {
+		return
+	}
+
+	dataLen, err := binary.ReadUvarint(c.reader)
+	if err != nil {
+		return
+	}
+
+	readLen := int(dataLen)
+	c.readRemaining = readLen
+	if len(b) > readLen {
+		b = b[:readLen]
+	}
+
+	n, err = c.reader.Read(b)
+	c.readRemaining -= n
+	return
+}
+
+func (c *GunConn) Write(b []byte) (n int, err error) {
+	protobufHeader := [1 + binary.MaxVarintLen64]byte{0x0A}
+	varuintLen := binary.PutUvarint(protobufHeader[1:], uint64(len(b)))
+	grpcHeader := buf.Get(5)
+	grpcPayloadLen := uint32(1 + varuintLen + len(b))
+	binary.BigEndian.PutUint32(grpcHeader[1:5], grpcPayloadLen)
+	_, err = bufio.Copy(c.writer, io.MultiReader(bytes.NewReader(grpcHeader), bytes.NewReader(protobufHeader[:varuintLen+1]), bytes.NewReader(b)))
+	buf.Put(grpcHeader)
+	if f, ok := c.writer.(http.Flusher); ok {
+		f.Flush()
+	}
+	return len(b), wrapError(err)
+}
+
+func uLen(x uint64) int {
+	i := 0
+	for x >= 0x80 {
+		x >>= 7
+		i++
+	}
+	return i + 1
+}
+
+func (c *GunConn) WriteBuffer(buffer *buf.Buffer) error {
+	defer buffer.Release()
+	dataLen := buffer.Len()
+	varLen := uLen(uint64(dataLen))
+	header := buffer.ExtendHeader(6 + varLen)
+	binary.BigEndian.PutUint32(header[1:5], uint32(1+varLen+dataLen))
+	header[5] = 0x0A
+	binary.PutUvarint(header[6:], uint64(dataLen))
+	err := rw.WriteBytes(c.writer, buffer.Bytes())
+	if c.flusher != nil {
+		c.flusher.Flush()
+	}
+	return wrapError(err)
+}
+
+func (c *GunConn) FrontHeadroom() int {
+	return 6 + binary.MaxVarintLen64
+}
+
+func (c *GunConn) Close() error {
+	return common.Close(c.reader, c.writer)
+}
+
+func (c *GunConn) LocalAddr() net.Addr {
+	return nil
+}
+
+func (c *GunConn) RemoteAddr() net.Addr {
+	return nil
+}
+
+func (c *GunConn) SetDeadline(t time.Time) error {
+	return os.ErrInvalid
+}
+
+func (c *GunConn) SetReadDeadline(t time.Time) error {
+	return os.ErrInvalid
+}
+
+func (c *GunConn) SetWriteDeadline(t time.Time) error {
+	return os.ErrInvalid
+}
+
+func wrapError(err error) error {
+	if E.IsMulti(err, io.ErrUnexpectedEOF) {
+		return io.EOF
+	}
+	return err
+}