Add xhttp transport

common/xray/buf/buffer.go

@@ -0,0 +1,337 @@
+package buf
+
+import (
+	"io"
+
+	"github.com/sagernet/sing-box/common/xray/bytespool"
+	"github.com/sagernet/sing-box/common/xray/net"
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+const (
+	// Size of a regular buffer.
+	Size = 8192
+)
+
+var zero = [Size * 10]byte{0}
+
+var pool = bytespool.GetPool(Size)
+
+// ownership represents the data owner of the buffer.
+type ownership uint8
+
+const (
+	managed ownership = iota
+	unmanaged
+	bytespools
+)
+
+// Buffer is a recyclable allocation of a byte array. Buffer.Release() recycles
+// the buffer into an internal buffer pool, in order to recreate a buffer more
+// quickly.
+type Buffer struct {
+	v         []byte
+	start     int32
+	end       int32
+	ownership ownership
+	UDP       *net.Destination
+}
+
+// New creates a Buffer with 0 length and 8K capacity, managed.
+func New() *Buffer {
+	buf := pool.Get().([]byte)
+	if cap(buf) >= Size {
+		buf = buf[:Size]
+	} else {
+		buf = make([]byte, Size)
+	}
+
+	return &Buffer{
+		v: buf,
+	}
+}
+
+// NewExisted creates a standard size Buffer with an existed bytearray, managed.
+func NewExisted(b []byte) *Buffer {
+	if cap(b) < Size {
+		panic("Invalid buffer")
+	}
+
+	oLen := len(b)
+	if oLen < Size {
+		b = b[:Size]
+	}
+
+	return &Buffer{
+		v:   b,
+		end: int32(oLen),
+	}
+}
+
+// FromBytes creates a Buffer with an existed bytearray, unmanaged.
+func FromBytes(b []byte) *Buffer {
+	return &Buffer{
+		v:         b,
+		end:       int32(len(b)),
+		ownership: unmanaged,
+	}
+}
+
+// StackNew creates a new Buffer object on stack, managed.
+// This method is for buffers that is released in the same function.
+func StackNew() Buffer {
+	buf := pool.Get().([]byte)
+	if cap(buf) >= Size {
+		buf = buf[:Size]
+	} else {
+		buf = make([]byte, Size)
+	}
+
+	return Buffer{
+		v: buf,
+	}
+}
+
+// NewWithSize creates a Buffer with 0 length and capacity with at least the given size, bytespool's.
+func NewWithSize(size int32) *Buffer {
+	return &Buffer{
+		v:         bytespool.Alloc(size),
+		ownership: bytespools,
+	}
+}
+
+// Release recycles the buffer into an internal buffer pool.
+func (b *Buffer) Release() {
+	if b == nil || b.v == nil || b.ownership == unmanaged {
+		return
+	}
+
+	p := b.v
+	b.v = nil
+	b.Clear()
+
+	switch b.ownership {
+	case managed:
+		if cap(p) == Size {
+			pool.Put(p)
+		}
+	case bytespools:
+		bytespool.Free(p)
+	}
+	b.UDP = nil
+}
+
+// Clear clears the content of the buffer, results an empty buffer with
+// Len() = 0.
+func (b *Buffer) Clear() {
+	b.start = 0
+	b.end = 0
+}
+
+// Byte returns the bytes at index.
+func (b *Buffer) Byte(index int32) byte {
+	return b.v[b.start+index]
+}
+
+// SetByte sets the byte value at index.
+func (b *Buffer) SetByte(index int32, value byte) {
+	b.v[b.start+index] = value
+}
+
+// Bytes returns the content bytes of this Buffer.
+func (b *Buffer) Bytes() []byte {
+	return b.v[b.start:b.end]
+}
+
+// Extend increases the buffer size by n bytes, and returns the extended part.
+// It panics if result size is larger than buf.Size.
+func (b *Buffer) Extend(n int32) []byte {
+	end := b.end + n
+	if end > int32(len(b.v)) {
+		panic("extending out of bound")
+	}
+	ext := b.v[b.end:end]
+	b.end = end
+	copy(ext, zero[:])
+	return ext
+}
+
+// BytesRange returns a slice of this buffer with given from and to boundary.
+func (b *Buffer) BytesRange(from, to int32) []byte {
+	if from < 0 {
+		from += b.Len()
+	}
+	if to < 0 {
+		to += b.Len()
+	}
+	return b.v[b.start+from : b.start+to]
+}
+
+// BytesFrom returns a slice of this Buffer starting from the given position.
+func (b *Buffer) BytesFrom(from int32) []byte {
+	if from < 0 {
+		from += b.Len()
+	}
+	return b.v[b.start+from : b.end]
+}
+
+// BytesTo returns a slice of this Buffer from start to the given position.
+func (b *Buffer) BytesTo(to int32) []byte {
+	if to < 0 {
+		to += b.Len()
+	}
+	if to < 0 {
+		to = 0
+	}
+	return b.v[b.start : b.start+to]
+}
+
+// Check makes sure that 0 <= b.start <= b.end.
+func (b *Buffer) Check() {
+	if b.start < 0 {
+		b.start = 0
+	}
+	if b.end < 0 {
+		b.end = 0
+	}
+	if b.start > b.end {
+		b.start = b.end
+	}
+}
+
+// Resize cuts the buffer at the given position.
+func (b *Buffer) Resize(from, to int32) {
+	oldEnd := b.end
+	if from < 0 {
+		from += b.Len()
+	}
+	if to < 0 {
+		to += b.Len()
+	}
+	if to < from {
+		panic("Invalid slice")
+	}
+	b.end = b.start + to
+	b.start += from
+	b.Check()
+	if b.end > oldEnd {
+		copy(b.v[oldEnd:b.end], zero[:])
+	}
+}
+
+// Advance cuts the buffer at the given position.
+func (b *Buffer) Advance(from int32) {
+	if from < 0 {
+		from += b.Len()
+	}
+	b.start += from
+	b.Check()
+}
+
+// Len returns the length of the buffer content.
+func (b *Buffer) Len() int32 {
+	if b == nil {
+		return 0
+	}
+	return b.end - b.start
+}
+
+// Cap returns the capacity of the buffer content.
+func (b *Buffer) Cap() int32 {
+	if b == nil {
+		return 0
+	}
+	return int32(len(b.v))
+}
+
+// IsEmpty returns true if the buffer is empty.
+func (b *Buffer) IsEmpty() bool {
+	return b.Len() == 0
+}
+
+// IsFull returns true if the buffer has no more room to grow.
+func (b *Buffer) IsFull() bool {
+	return b != nil && b.end == int32(len(b.v))
+}
+
+// Write implements Write method in io.Writer.
+func (b *Buffer) Write(data []byte) (int, error) {
+	nBytes := copy(b.v[b.end:], data)
+	b.end += int32(nBytes)
+	return nBytes, nil
+}
+
+// WriteByte writes a single byte into the buffer.
+func (b *Buffer) WriteByte(v byte) error {
+	if b.IsFull() {
+		return E.New("buffer full")
+	}
+	b.v[b.end] = v
+	b.end++
+	return nil
+}
+
+// WriteString implements io.StringWriter.
+func (b *Buffer) WriteString(s string) (int, error) {
+	return b.Write([]byte(s))
+}
+
+// ReadByte implements io.ByteReader
+func (b *Buffer) ReadByte() (byte, error) {
+	if b.start == b.end {
+		return 0, io.EOF
+	}
+
+	nb := b.v[b.start]
+	b.start++
+	return nb, nil
+}
+
+// ReadBytes implements bufio.Reader.ReadBytes
+func (b *Buffer) ReadBytes(length int32) ([]byte, error) {
+	if b.end-b.start < length {
+		return nil, io.EOF
+	}
+
+	nb := b.v[b.start : b.start+length]
+	b.start += length
+	return nb, nil
+}
+
+// Read implements io.Reader.Read().
+func (b *Buffer) Read(data []byte) (int, error) {
+	if b.Len() == 0 {
+		return 0, io.EOF
+	}
+	nBytes := copy(data, b.v[b.start:b.end])
+	if int32(nBytes) == b.Len() {
+		b.Clear()
+	} else {
+		b.start += int32(nBytes)
+	}
+	return nBytes, nil
+}
+
+// ReadFrom implements io.ReaderFrom.
+func (b *Buffer) ReadFrom(reader io.Reader) (int64, error) {
+	n, err := reader.Read(b.v[b.end:])
+	b.end += int32(n)
+	return int64(n), err
+}
+
+// ReadFullFrom reads exact size of bytes from given reader, or until error occurs.
+func (b *Buffer) ReadFullFrom(reader io.Reader, size int32) (int64, error) {
+	end := b.end + size
+	if end > int32(len(b.v)) {
+		v := end
+		return 0, E.New("out of bound: ", v)
+	}
+	n, err := io.ReadFull(reader, b.v[b.end:end])
+	b.end += int32(n)
+	return int64(n), err
+}
+
+// String returns the string form of this Buffer.
+func (b *Buffer) String() string {
+	return string(b.Bytes())
+}

common/xray/buf/copy.go

@@ -0,0 +1,124 @@
+package buf
+
+import (
+	"io"
+	"time"
+
+	"github.com/sagernet/sing-box/common/xray/errors"
+	"github.com/sagernet/sing-box/common/xray/signal"
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+type dataHandler func(MultiBuffer)
+
+type copyHandler struct {
+	onData []dataHandler
+}
+
+// SizeCounter is for counting bytes copied by Copy().
+type SizeCounter struct {
+	Size int64
+}
+
+// CopyOption is an option for copying data.
+type CopyOption func(*copyHandler)
+
+// UpdateActivity is a CopyOption to update activity on each data copy operation.
+func UpdateActivity(timer signal.ActivityUpdater) CopyOption {
+	return func(handler *copyHandler) {
+		handler.onData = append(handler.onData, func(MultiBuffer) {
+			timer.Update()
+		})
+	}
+}
+
+// CountSize is a CopyOption that sums the total size of data copied into the given SizeCounter.
+func CountSize(sc *SizeCounter) CopyOption {
+	return func(handler *copyHandler) {
+		handler.onData = append(handler.onData, func(b MultiBuffer) {
+			sc.Size += int64(b.Len())
+		})
+	}
+}
+
+type readError struct {
+	error
+}
+
+func (e readError) Error() string {
+	return e.error.Error()
+}
+
+func (e readError) Unwrap() error {
+	return e.error
+}
+
+// IsReadError returns true if the error in Copy() comes from reading.
+func IsReadError(err error) bool {
+	_, ok := err.(readError)
+	return ok
+}
+
+type writeError struct {
+	error
+}
+
+func (e writeError) Error() string {
+	return e.error.Error()
+}
+
+func (e writeError) Unwrap() error {
+	return e.error
+}
+
+// IsWriteError returns true if the error in Copy() comes from writing.
+func IsWriteError(err error) bool {
+	_, ok := err.(writeError)
+	return ok
+}
+
+func copyInternal(reader Reader, writer Writer, handler *copyHandler) error {
+	for {
+		buffer, err := reader.ReadMultiBuffer()
+		if !buffer.IsEmpty() {
+			for _, handler := range handler.onData {
+				handler(buffer)
+			}
+
+			if werr := writer.WriteMultiBuffer(buffer); werr != nil {
+				return writeError{werr}
+			}
+		}
+
+		if err != nil {
+			return readError{err}
+		}
+	}
+}
+
+// Copy dumps all payload from reader to writer or stops when an error occurs. It returns nil when EOF.
+func Copy(reader Reader, writer Writer, options ...CopyOption) error {
+	var handler copyHandler
+	for _, option := range options {
+		option(&handler)
+	}
+	err := copyInternal(reader, writer, &handler)
+	if err != nil && errors.Cause(err) != io.EOF {
+		return err
+	}
+	return nil
+}
+
+var ErrNotTimeoutReader = E.New("not a TimeoutReader")
+
+func CopyOnceTimeout(reader Reader, writer Writer, timeout time.Duration) error {
+	timeoutReader, ok := reader.(TimeoutReader)
+	if !ok {
+		return ErrNotTimeoutReader
+	}
+	mb, err := timeoutReader.ReadMultiBufferTimeout(timeout)
+	if err != nil {
+		return err
+	}
+	return writer.WriteMultiBuffer(mb)
+}

common/xray/buf/io.go

@@ -0,0 +1,126 @@
+package buf
+
+import (
+	"io"
+	"net"
+	"syscall"
+	"time"
+
+	"github.com/sagernet/sing-box/common/xray/stat"
+	"github.com/sagernet/sing-box/common/xray/stats"
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+// Reader extends io.Reader with MultiBuffer.
+type Reader interface {
+	// ReadMultiBuffer reads content from underlying reader, and put it into a MultiBuffer.
+	ReadMultiBuffer() (MultiBuffer, error)
+}
+
+// ErrReadTimeout is an error that happens with IO timeout.
+var ErrReadTimeout = E.New("IO timeout")
+
+// TimeoutReader is a reader that returns error if Read() operation takes longer than the given timeout.
+type TimeoutReader interface {
+	ReadMultiBufferTimeout(time.Duration) (MultiBuffer, error)
+}
+
+// Writer extends io.Writer with MultiBuffer.
+type Writer interface {
+	// WriteMultiBuffer writes a MultiBuffer into underlying writer.
+	WriteMultiBuffer(MultiBuffer) error
+}
+
+// WriteAllBytes ensures all bytes are written into the given writer.
+func WriteAllBytes(writer io.Writer, payload []byte, c stats.Counter) error {
+	wc := 0
+	defer func() {
+		if c != nil {
+			c.Add(int64(wc))
+		}
+	}()
+
+	for len(payload) > 0 {
+		n, err := writer.Write(payload)
+		wc += n
+		if err != nil {
+			return err
+		}
+		payload = payload[n:]
+	}
+	return nil
+}
+
+func isPacketReader(reader io.Reader) bool {
+	_, ok := reader.(net.PacketConn)
+	return ok
+}
+
+// NewReader creates a new Reader.
+// The Reader instance doesn't take the ownership of reader.
+func NewReader(reader io.Reader) Reader {
+	if mr, ok := reader.(Reader); ok {
+		return mr
+	}
+
+	if isPacketReader(reader) {
+		return &PacketReader{
+			Reader: reader,
+		}
+	}
+
+	return &SingleReader{
+		Reader: reader,
+	}
+}
+
+// NewPacketReader creates a new PacketReader based on the given reader.
+func NewPacketReader(reader io.Reader) Reader {
+	if mr, ok := reader.(Reader); ok {
+		return mr
+	}
+
+	return &PacketReader{
+		Reader: reader,
+	}
+}
+
+func isPacketWriter(writer io.Writer) bool {
+	if _, ok := writer.(net.PacketConn); ok {
+		return true
+	}
+
+	// If the writer doesn't implement syscall.Conn, it is probably not a TCP connection.
+	if _, ok := writer.(syscall.Conn); !ok {
+		return true
+	}
+	return false
+}
+
+// NewWriter creates a new Writer.
+func NewWriter(writer io.Writer) Writer {
+	if mw, ok := writer.(Writer); ok {
+		return mw
+	}
+
+	iConn := writer
+	if statConn, ok := writer.(*stat.CounterConnection); ok {
+		iConn = statConn.Connection
+	}
+
+	if isPacketWriter(iConn) {
+		return &SequentialWriter{
+			Writer: writer,
+		}
+	}
+
+	var counter stats.Counter
+
+	if statConn, ok := writer.(*stat.CounterConnection); ok {
+		counter = statConn.WriteCounter
+	}
+	return &BufferToBytesWriter{
+		Writer:  iConn,
+		counter: counter,
+	}
+}

common/xray/buf/multi_buffer.go

@@ -0,0 +1,310 @@
+package buf
+
+import (
+	"io"
+
+	"github.com/sagernet/sing-box/common/xray"
+	"github.com/sagernet/sing-box/common/xray/errors"
+	"github.com/sagernet/sing-box/common/xray/serial"
+)
+
+// ReadAllToBytes reads all content from the reader into a byte array, until EOF.
+func ReadAllToBytes(reader io.Reader) ([]byte, error) {
+	mb, err := ReadFrom(reader)
+	if err != nil {
+		return nil, err
+	}
+	if mb.Len() == 0 {
+		return nil, nil
+	}
+	b := make([]byte, mb.Len())
+	mb, _ = SplitBytes(mb, b)
+	ReleaseMulti(mb)
+	return b, nil
+}
+
+// MultiBuffer is a list of Buffers. The order of Buffer matters.
+type MultiBuffer []*Buffer
+
+// MergeMulti merges content from src to dest, and returns the new address of dest and src
+func MergeMulti(dest MultiBuffer, src MultiBuffer) (MultiBuffer, MultiBuffer) {
+	dest = append(dest, src...)
+	for idx := range src {
+		src[idx] = nil
+	}
+	return dest, src[:0]
+}
+
+// MergeBytes merges the given bytes into MultiBuffer and return the new address of the merged MultiBuffer.
+func MergeBytes(dest MultiBuffer, src []byte) MultiBuffer {
+	n := len(dest)
+	if n > 0 && !(dest)[n-1].IsFull() {
+		nBytes, _ := (dest)[n-1].Write(src)
+		src = src[nBytes:]
+	}
+
+	for len(src) > 0 {
+		b := New()
+		nBytes, _ := b.Write(src)
+		src = src[nBytes:]
+		dest = append(dest, b)
+	}
+
+	return dest
+}
+
+// ReleaseMulti releases all content of the MultiBuffer, and returns an empty MultiBuffer.
+func ReleaseMulti(mb MultiBuffer) MultiBuffer {
+	for i := range mb {
+		mb[i].Release()
+		mb[i] = nil
+	}
+	return mb[:0]
+}
+
+// Copy copied the beginning part of the MultiBuffer into the given byte array.
+func (mb MultiBuffer) Copy(b []byte) int {
+	total := 0
+	for _, bb := range mb {
+		nBytes := copy(b[total:], bb.Bytes())
+		total += nBytes
+		if int32(nBytes) < bb.Len() {
+			break
+		}
+	}
+	return total
+}
+
+// ReadFrom reads all content from reader until EOF.
+func ReadFrom(reader io.Reader) (MultiBuffer, error) {
+	mb := make(MultiBuffer, 0, 16)
+	for {
+		b := New()
+		_, err := b.ReadFullFrom(reader, Size)
+		if b.IsEmpty() {
+			b.Release()
+		} else {
+			mb = append(mb, b)
+		}
+		if err != nil {
+			if errors.Cause(err) == io.EOF || errors.Cause(err) == io.ErrUnexpectedEOF {
+				return mb, nil
+			}
+			return mb, err
+		}
+	}
+}
+
+// SplitBytes splits the given amount of bytes from the beginning of the MultiBuffer.
+// It returns the new address of MultiBuffer leftover, and number of bytes written into the input byte slice.
+func SplitBytes(mb MultiBuffer, b []byte) (MultiBuffer, int) {
+	totalBytes := 0
+	endIndex := -1
+	for i := range mb {
+		pBuffer := mb[i]
+		nBytes, _ := pBuffer.Read(b)
+		totalBytes += nBytes
+		b = b[nBytes:]
+		if !pBuffer.IsEmpty() {
+			endIndex = i
+			break
+		}
+		pBuffer.Release()
+		mb[i] = nil
+	}
+
+	if endIndex == -1 {
+		mb = mb[:0]
+	} else {
+		mb = mb[endIndex:]
+	}
+
+	return mb, totalBytes
+}
+
+// SplitFirstBytes splits the first buffer from MultiBuffer, and then copy its content into the given slice.
+func SplitFirstBytes(mb MultiBuffer, p []byte) (MultiBuffer, int) {
+	mb, b := SplitFirst(mb)
+	if b == nil {
+		return mb, 0
+	}
+	n := copy(p, b.Bytes())
+	b.Release()
+	return mb, n
+}
+
+// Compact returns another MultiBuffer by merging all content of the given one together.
+func Compact(mb MultiBuffer) MultiBuffer {
+	if len(mb) == 0 {
+		return mb
+	}
+
+	mb2 := make(MultiBuffer, 0, len(mb))
+	last := mb[0]
+
+	for i := 1; i < len(mb); i++ {
+		curr := mb[i]
+		if last.Len()+curr.Len() > Size {
+			mb2 = append(mb2, last)
+			last = curr
+		} else {
+			common.Must2(last.ReadFrom(curr))
+			curr.Release()
+		}
+	}
+
+	mb2 = append(mb2, last)
+	return mb2
+}
+
+// SplitFirst splits the first Buffer from the beginning of the MultiBuffer.
+func SplitFirst(mb MultiBuffer) (MultiBuffer, *Buffer) {
+	if len(mb) == 0 {
+		return mb, nil
+	}
+
+	b := mb[0]
+	mb[0] = nil
+	mb = mb[1:]
+	return mb, b
+}
+
+// SplitSize splits the beginning of the MultiBuffer into another one, for at most size bytes.
+func SplitSize(mb MultiBuffer, size int32) (MultiBuffer, MultiBuffer) {
+	if len(mb) == 0 {
+		return mb, nil
+	}
+
+	if mb[0].Len() > size {
+		b := New()
+		copy(b.Extend(size), mb[0].BytesTo(size))
+		mb[0].Advance(size)
+		return mb, MultiBuffer{b}
+	}
+
+	totalBytes := int32(0)
+	var r MultiBuffer
+	endIndex := -1
+	for i := range mb {
+		if totalBytes+mb[i].Len() > size {
+			endIndex = i
+			break
+		}
+		totalBytes += mb[i].Len()
+		r = append(r, mb[i])
+		mb[i] = nil
+	}
+	if endIndex == -1 {
+		// To reuse mb array
+		mb = mb[:0]
+	} else {
+		mb = mb[endIndex:]
+	}
+	return mb, r
+}
+
+// SplitMulti splits the beginning of the MultiBuffer into first one, the index i and after into second one
+func SplitMulti(mb MultiBuffer, i int) (MultiBuffer, MultiBuffer) {
+	mb2 := make(MultiBuffer, 0, len(mb))
+	if i < len(mb) && i >= 0 {
+		mb2 = append(mb2, mb[i:]...)
+		for j := i; j < len(mb); j++ {
+			mb[j] = nil
+		}
+		mb = mb[:i]
+	}
+	return mb, mb2
+}
+
+// WriteMultiBuffer writes all buffers from the MultiBuffer to the Writer one by one, and return error if any, with leftover MultiBuffer.
+func WriteMultiBuffer(writer io.Writer, mb MultiBuffer) (MultiBuffer, error) {
+	for {
+		mb2, b := SplitFirst(mb)
+		mb = mb2
+		if b == nil {
+			break
+		}
+
+		_, err := writer.Write(b.Bytes())
+		b.Release()
+		if err != nil {
+			return mb, err
+		}
+	}
+
+	return nil, nil
+}
+
+// Len returns the total number of bytes in the MultiBuffer.
+func (mb MultiBuffer) Len() int32 {
+	if mb == nil {
+		return 0
+	}
+
+	size := int32(0)
+	for _, b := range mb {
+		size += b.Len()
+	}
+	return size
+}
+
+// IsEmpty returns true if the MultiBuffer has no content.
+func (mb MultiBuffer) IsEmpty() bool {
+	for _, b := range mb {
+		if !b.IsEmpty() {
+			return false
+		}
+	}
+	return true
+}
+
+// String returns the content of the MultiBuffer in string.
+func (mb MultiBuffer) String() string {
+	v := make([]interface{}, len(mb))
+	for i, b := range mb {
+		v[i] = b
+	}
+	return serial.Concat(v...)
+}
+
+// MultiBufferContainer is a ReadWriteCloser wrapper over MultiBuffer.
+type MultiBufferContainer struct {
+	MultiBuffer
+}
+
+// Read implements io.Reader.
+func (c *MultiBufferContainer) Read(b []byte) (int, error) {
+	if c.MultiBuffer.IsEmpty() {
+		return 0, io.EOF
+	}
+
+	mb, nBytes := SplitBytes(c.MultiBuffer, b)
+	c.MultiBuffer = mb
+	return nBytes, nil
+}
+
+// ReadMultiBuffer implements Reader.
+func (c *MultiBufferContainer) ReadMultiBuffer() (MultiBuffer, error) {
+	mb := c.MultiBuffer
+	c.MultiBuffer = nil
+	return mb, nil
+}
+
+// Write implements io.Writer.
+func (c *MultiBufferContainer) Write(b []byte) (int, error) {
+	c.MultiBuffer = MergeBytes(c.MultiBuffer, b)
+	return len(b), nil
+}
+
+// WriteMultiBuffer implements Writer.
+func (c *MultiBufferContainer) WriteMultiBuffer(b MultiBuffer) error {
+	mb, _ := MergeMulti(c.MultiBuffer, b)
+	c.MultiBuffer = mb
+	return nil
+}
+
+// Close implements io.Closer.
+func (c *MultiBufferContainer) Close() error {
+	c.MultiBuffer = ReleaseMulti(c.MultiBuffer)
+	return nil
+}

common/xray/buf/override.go

@@ -0,0 +1,38 @@
+package buf
+
+import (
+	"github.com/sagernet/sing-box/common/xray/net"
+)
+
+type EndpointOverrideReader struct {
+	Reader
+	Dest         net.Address
+	OriginalDest net.Address
+}
+
+func (r *EndpointOverrideReader) ReadMultiBuffer() (MultiBuffer, error) {
+	mb, err := r.Reader.ReadMultiBuffer()
+	if err == nil {
+		for _, b := range mb {
+			if b.UDP != nil && b.UDP.Address == r.OriginalDest {
+				b.UDP.Address = r.Dest
+			}
+		}
+	}
+	return mb, err
+}
+
+type EndpointOverrideWriter struct {
+	Writer
+	Dest         net.Address
+	OriginalDest net.Address
+}
+
+func (w *EndpointOverrideWriter) WriteMultiBuffer(mb MultiBuffer) error {
+	for _, b := range mb {
+		if b.UDP != nil && b.UDP.Address == w.Dest {
+			b.UDP.Address = w.OriginalDest
+		}
+	}
+	return w.Writer.WriteMultiBuffer(mb)
+}

common/xray/buf/reader.go

@@ -0,0 +1,175 @@
+package buf
+
+import (
+	"io"
+
+	"github.com/sagernet/sing-box/common/xray"
+	"github.com/sagernet/sing-box/common/xray/errors"
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+func readOneUDP(r io.Reader) (*Buffer, error) {
+	b := New()
+	for i := 0; i < 64; i++ {
+		_, err := b.ReadFrom(r)
+		if !b.IsEmpty() {
+			return b, nil
+		}
+		if err != nil {
+			b.Release()
+			return nil, err
+		}
+	}
+
+	b.Release()
+	return nil, E.New("Reader returns too many empty payloads.")
+}
+
+// ReadBuffer reads a Buffer from the given reader.
+func ReadBuffer(r io.Reader) (*Buffer, error) {
+	b := New()
+	n, err := b.ReadFrom(r)
+	if n > 0 {
+		return b, err
+	}
+	b.Release()
+	return nil, err
+}
+
+// BufferedReader is a Reader that keeps its internal buffer.
+type BufferedReader struct {
+	// Reader is the underlying reader to be read from
+	Reader Reader
+	// Buffer is the internal buffer to be read from first
+	Buffer MultiBuffer
+	// Splitter is a function to read bytes from MultiBuffer
+	Splitter func(MultiBuffer, []byte) (MultiBuffer, int)
+}
+
+// BufferedBytes returns the number of bytes that is cached in this reader.
+func (r *BufferedReader) BufferedBytes() int32 {
+	return r.Buffer.Len()
+}
+
+// ReadByte implements io.ByteReader.
+func (r *BufferedReader) ReadByte() (byte, error) {
+	var b [1]byte
+	_, err := r.Read(b[:])
+	return b[0], err
+}
+
+// Read implements io.Reader. It reads from internal buffer first (if available) and then reads from the underlying reader.
+func (r *BufferedReader) Read(b []byte) (int, error) {
+	spliter := r.Splitter
+	if spliter == nil {
+		spliter = SplitBytes
+	}
+
+	if !r.Buffer.IsEmpty() {
+		buffer, nBytes := spliter(r.Buffer, b)
+		r.Buffer = buffer
+		if r.Buffer.IsEmpty() {
+			r.Buffer = nil
+		}
+		return nBytes, nil
+	}
+
+	mb, err := r.Reader.ReadMultiBuffer()
+	if err != nil {
+		return 0, err
+	}
+
+	mb, nBytes := spliter(mb, b)
+	if !mb.IsEmpty() {
+		r.Buffer = mb
+	}
+	return nBytes, nil
+}
+
+// ReadMultiBuffer implements Reader.
+func (r *BufferedReader) ReadMultiBuffer() (MultiBuffer, error) {
+	if !r.Buffer.IsEmpty() {
+		mb := r.Buffer
+		r.Buffer = nil
+		return mb, nil
+	}
+
+	return r.Reader.ReadMultiBuffer()
+}
+
+// ReadAtMost returns a MultiBuffer with at most size.
+func (r *BufferedReader) ReadAtMost(size int32) (MultiBuffer, error) {
+	if r.Buffer.IsEmpty() {
+		mb, err := r.Reader.ReadMultiBuffer()
+		if mb.IsEmpty() && err != nil {
+			return nil, err
+		}
+		r.Buffer = mb
+	}
+
+	rb, mb := SplitSize(r.Buffer, size)
+	r.Buffer = rb
+	if r.Buffer.IsEmpty() {
+		r.Buffer = nil
+	}
+	return mb, nil
+}
+
+func (r *BufferedReader) writeToInternal(writer io.Writer) (int64, error) {
+	mbWriter := NewWriter(writer)
+	var sc SizeCounter
+	if r.Buffer != nil {
+		sc.Size = int64(r.Buffer.Len())
+		if err := mbWriter.WriteMultiBuffer(r.Buffer); err != nil {
+			return 0, err
+		}
+		r.Buffer = nil
+	}
+
+	err := Copy(r.Reader, mbWriter, CountSize(&sc))
+	return sc.Size, err
+}
+
+// WriteTo implements io.WriterTo.
+func (r *BufferedReader) WriteTo(writer io.Writer) (int64, error) {
+	nBytes, err := r.writeToInternal(writer)
+	if errors.Cause(err) == io.EOF {
+		return nBytes, nil
+	}
+	return nBytes, err
+}
+
+// Interrupt implements common.Interruptible.
+func (r *BufferedReader) Interrupt() {
+	common.Interrupt(r.Reader)
+}
+
+// Close implements io.Closer.
+func (r *BufferedReader) Close() error {
+	return common.Close(r.Reader)
+}
+
+// SingleReader is a Reader that read one Buffer every time.
+type SingleReader struct {
+	io.Reader
+}
+
+// ReadMultiBuffer implements Reader.
+func (r *SingleReader) ReadMultiBuffer() (MultiBuffer, error) {
+	b, err := ReadBuffer(r.Reader)
+	return MultiBuffer{b}, err
+}
+
+// PacketReader is a Reader that read one Buffer every time.
+type PacketReader struct {
+	io.Reader
+}
+
+// ReadMultiBuffer implements Reader.
+func (r *PacketReader) ReadMultiBuffer() (MultiBuffer, error) {
+	b, err := readOneUDP(r.Reader)
+	if err != nil {
+		return nil, err
+	}
+	return MultiBuffer{b}, nil
+}

common/xray/buf/writer.go

@@ -0,0 +1,270 @@
+package buf
+
+import (
+	"io"
+	"net"
+	"sync"
+
+	"github.com/sagernet/sing-box/common/xray"
+	"github.com/sagernet/sing-box/common/xray/errors"
+	"github.com/sagernet/sing-box/common/xray/stats"
+)
+
+// BufferToBytesWriter is a Writer that writes alloc.Buffer into underlying writer.
+type BufferToBytesWriter struct {
+	io.Writer
+
+	counter stats.Counter
+	cache   [][]byte
+}
+
+// WriteMultiBuffer implements Writer. This method takes ownership of the given buffer.
+func (w *BufferToBytesWriter) WriteMultiBuffer(mb MultiBuffer) error {
+	defer ReleaseMulti(mb)
+
+	size := mb.Len()
+	if size == 0 {
+		return nil
+	}
+
+	if len(mb) == 1 {
+		return WriteAllBytes(w.Writer, mb[0].Bytes(), w.counter)
+	}
+
+	if cap(w.cache) < len(mb) {
+		w.cache = make([][]byte, 0, len(mb))
+	}
+
+	bs := w.cache
+	for _, b := range mb {
+		bs = append(bs, b.Bytes())
+	}
+
+	defer func() {
+		for idx := range bs {
+			bs[idx] = nil
+		}
+	}()
+
+	nb := net.Buffers(bs)
+	wc := int64(0)
+	defer func() {
+		if w.counter != nil {
+			w.counter.Add(wc)
+		}
+	}()
+	for size > 0 {
+		n, err := nb.WriteTo(w.Writer)
+		wc += n
+		if err != nil {
+			return err
+		}
+		size -= int32(n)
+	}
+
+	return nil
+}
+
+// ReadFrom implements io.ReaderFrom.
+func (w *BufferToBytesWriter) ReadFrom(reader io.Reader) (int64, error) {
+	var sc SizeCounter
+	err := Copy(NewReader(reader), w, CountSize(&sc))
+	return sc.Size, err
+}
+
+// BufferedWriter is a Writer with internal buffer.
+type BufferedWriter struct {
+	sync.Mutex
+	writer   Writer
+	buffer   *Buffer
+	buffered bool
+}
+
+// NewBufferedWriter creates a new BufferedWriter.
+func NewBufferedWriter(writer Writer) *BufferedWriter {
+	return &BufferedWriter{
+		writer:   writer,
+		buffer:   New(),
+		buffered: true,
+	}
+}
+
+// WriteByte implements io.ByteWriter.
+func (w *BufferedWriter) WriteByte(c byte) error {
+	return common.Error2(w.Write([]byte{c}))
+}
+
+// Write implements io.Writer.
+func (w *BufferedWriter) Write(b []byte) (int, error) {
+	if len(b) == 0 {
+		return 0, nil
+	}
+
+	w.Lock()
+	defer w.Unlock()
+
+	if !w.buffered {
+		if writer, ok := w.writer.(io.Writer); ok {
+			return writer.Write(b)
+		}
+	}
+
+	totalBytes := 0
+	for len(b) > 0 {
+		if w.buffer == nil {
+			w.buffer = New()
+		}
+
+		nBytes, err := w.buffer.Write(b)
+		totalBytes += nBytes
+		if err != nil {
+			return totalBytes, err
+		}
+		if !w.buffered || w.buffer.IsFull() {
+			if err := w.flushInternal(); err != nil {
+				return totalBytes, err
+			}
+		}
+		b = b[nBytes:]
+	}
+
+	return totalBytes, nil
+}
+
+// WriteMultiBuffer implements Writer. It takes ownership of the given MultiBuffer.
+func (w *BufferedWriter) WriteMultiBuffer(b MultiBuffer) error {
+	if b.IsEmpty() {
+		return nil
+	}
+
+	w.Lock()
+	defer w.Unlock()
+
+	if !w.buffered {
+		return w.writer.WriteMultiBuffer(b)
+	}
+
+	reader := MultiBufferContainer{
+		MultiBuffer: b,
+	}
+	defer reader.Close()
+
+	for !reader.MultiBuffer.IsEmpty() {
+		if w.buffer == nil {
+			w.buffer = New()
+		}
+		common.Must2(w.buffer.ReadFrom(&reader))
+		if w.buffer.IsFull() {
+			if err := w.flushInternal(); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+// Flush flushes buffered content into underlying writer.
+func (w *BufferedWriter) Flush() error {
+	w.Lock()
+	defer w.Unlock()
+
+	return w.flushInternal()
+}
+
+func (w *BufferedWriter) flushInternal() error {
+	if w.buffer.IsEmpty() {
+		return nil
+	}
+
+	b := w.buffer
+	w.buffer = nil
+
+	if writer, ok := w.writer.(io.Writer); ok {
+		err := WriteAllBytes(writer, b.Bytes(), nil)
+		b.Release()
+		return err
+	}
+
+	return w.writer.WriteMultiBuffer(MultiBuffer{b})
+}
+
+// SetBuffered sets whether the internal buffer is used. If set to false, Flush() will be called to clear the buffer.
+func (w *BufferedWriter) SetBuffered(f bool) error {
+	w.Lock()
+	defer w.Unlock()
+
+	w.buffered = f
+	if !f {
+		return w.flushInternal()
+	}
+	return nil
+}
+
+// ReadFrom implements io.ReaderFrom.
+func (w *BufferedWriter) ReadFrom(reader io.Reader) (int64, error) {
+	if err := w.SetBuffered(false); err != nil {
+		return 0, err
+	}
+
+	var sc SizeCounter
+	err := Copy(NewReader(reader), w, CountSize(&sc))
+	return sc.Size, err
+}
+
+// Close implements io.Closable.
+func (w *BufferedWriter) Close() error {
+	if err := w.Flush(); err != nil {
+		return err
+	}
+	return common.Close(w.writer)
+}
+
+// SequentialWriter is a Writer that writes MultiBuffer sequentially into the underlying io.Writer.
+type SequentialWriter struct {
+	io.Writer
+}
+
+// WriteMultiBuffer implements Writer.
+func (w *SequentialWriter) WriteMultiBuffer(mb MultiBuffer) error {
+	mb, err := WriteMultiBuffer(w.Writer, mb)
+	ReleaseMulti(mb)
+	return err
+}
+
+type noOpWriter byte
+
+func (noOpWriter) WriteMultiBuffer(b MultiBuffer) error {
+	ReleaseMulti(b)
+	return nil
+}
+
+func (noOpWriter) Write(b []byte) (int, error) {
+	return len(b), nil
+}
+
+func (noOpWriter) ReadFrom(reader io.Reader) (int64, error) {
+	b := New()
+	defer b.Release()
+
+	totalBytes := int64(0)
+	for {
+		b.Clear()
+		_, err := b.ReadFrom(reader)
+		totalBytes += int64(b.Len())
+		if err != nil {
+			if errors.Cause(err) == io.EOF {
+				return totalBytes, nil
+			}
+			return totalBytes, err
+		}
+	}
+}
+
+var (
+	// Discard is a Writer that swallows all contents written in.
+	Discard Writer = noOpWriter(0)
+
+	// DiscardBytes is an io.Writer that swallows all contents written in.
+	DiscardBytes io.Writer = noOpWriter(0)
+)