Feature: experimental support snell

component/snell/cipher.go

@@ -0,0 +1,21 @@
+package snell
+
+import (
+	"crypto/cipher"
+
+	"golang.org/x/crypto/argon2"
+)
+
+type snellCipher struct {
+	psk      []byte
+	makeAEAD func(key []byte) (cipher.AEAD, error)
+}
+
+func (sc *snellCipher) KeySize() int  { return 32 }
+func (sc *snellCipher) SaltSize() int { return 16 }
+func (sc *snellCipher) Encrypter(salt []byte) (cipher.AEAD, error) {
+	return sc.makeAEAD(argon2.IDKey(sc.psk, salt, 3, 8, 1, uint32(sc.KeySize())))
+}
+func (sc *snellCipher) Decrypter(salt []byte) (cipher.AEAD, error) {
+	return sc.makeAEAD(argon2.IDKey(sc.psk, salt, 3, 8, 1, uint32(sc.KeySize())))
+}

component/snell/snell.go

@@ -0,0 +1,91 @@
+package snell
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"io"
+	"net"
+	"sync"
+
+	"github.com/Dreamacro/go-shadowsocks2/shadowaead"
+	"golang.org/x/crypto/chacha20poly1305"
+)
+
+const (
+	CommandPing    byte = 0
+	CommandConnect byte = 1
+
+	CommandTunnel byte = 0
+	CommandError  byte = 2
+
+	Version byte = 1
+)
+
+var (
+	bufferPool = sync.Pool{New: func() interface{} { return &bytes.Buffer{} }}
+)
+
+type Snell struct {
+	net.Conn
+	buffer [1]byte
+	reply  bool
+}
+
+func (s *Snell) Read(b []byte) (int, error) {
+	if s.reply {
+		return s.Conn.Read(b)
+	}
+
+	s.reply = true
+	if _, err := io.ReadFull(s.Conn, s.buffer[:]); err != nil {
+		return 0, err
+	}
+
+	if s.buffer[0] == CommandTunnel {
+		return s.Conn.Read(b)
+	} else if s.buffer[0] != CommandError {
+		return 0, errors.New("Command not support")
+	}
+
+	// CommandError
+	if _, err := io.ReadFull(s.Conn, s.buffer[:]); err != nil {
+		return 0, err
+	}
+
+	length := int(s.buffer[0])
+	msg := make([]byte, length)
+
+	if _, err := io.ReadFull(s.Conn, msg); err != nil {
+		return 0, err
+	}
+
+	return 0, errors.New(string(msg))
+}
+
+func WriteHeader(conn net.Conn, host string, port uint) error {
+	buf := bufferPool.Get().(*bytes.Buffer)
+	buf.Reset()
+	defer bufferPool.Put(buf)
+	buf.WriteByte(Version)
+	buf.WriteByte(CommandConnect)
+
+	// clientID length & id
+	buf.WriteByte(0)
+
+	// host & port
+	buf.WriteByte(uint8(len(host)))
+	buf.WriteString(host)
+	binary.Write(buf, binary.BigEndian, uint16(port))
+
+	if _, err := conn.Write(buf.Bytes()); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func StreamConn(conn net.Conn, psk []byte) net.Conn {
+	cipher := &snellCipher{psk, chacha20poly1305.New}
+	return &Snell{Conn: shadowaead.NewConn(conn, cipher)}
+}