Chore: embed shadowsocks2

transport/shadowsocks/core/cipher.go

@@ -0,0 +1,164 @@
+package core
+
+import (
+	"crypto/md5"
+	"errors"
+	"net"
+	"sort"
+	"strings"
+
+	"github.com/Dreamacro/clash/transport/shadowsocks/shadowaead"
+	"github.com/Dreamacro/clash/transport/shadowsocks/shadowstream"
+)
+
+type Cipher interface {
+	StreamConnCipher
+	PacketConnCipher
+}
+
+type StreamConnCipher interface {
+	StreamConn(net.Conn) net.Conn
+}
+
+type PacketConnCipher interface {
+	PacketConn(net.PacketConn) net.PacketConn
+}
+
+// ErrCipherNotSupported occurs when a cipher is not supported (likely because of security concerns).
+var ErrCipherNotSupported = errors.New("cipher not supported")
+
+const (
+	aeadAes128Gcm         = "AEAD_AES_128_GCM"
+	aeadAes192Gcm         = "AEAD_AES_192_GCM"
+	aeadAes256Gcm         = "AEAD_AES_256_GCM"
+	aeadChacha20Poly1305  = "AEAD_CHACHA20_POLY1305"
+	aeadXChacha20Poly1305 = "AEAD_XCHACHA20_POLY1305"
+)
+
+// List of AEAD ciphers: key size in bytes and constructor
+var aeadList = map[string]struct {
+	KeySize int
+	New     func([]byte) (shadowaead.Cipher, error)
+}{
+	aeadAes128Gcm:         {16, shadowaead.AESGCM},
+	aeadAes192Gcm:         {24, shadowaead.AESGCM},
+	aeadAes256Gcm:         {32, shadowaead.AESGCM},
+	aeadChacha20Poly1305:  {32, shadowaead.Chacha20Poly1305},
+	aeadXChacha20Poly1305: {32, shadowaead.XChacha20Poly1305},
+}
+
+// List of stream ciphers: key size in bytes and constructor
+var streamList = map[string]struct {
+	KeySize int
+	New     func(key []byte) (shadowstream.Cipher, error)
+}{
+	"RC4-MD5":       {16, shadowstream.RC4MD5},
+	"AES-128-CTR":   {16, shadowstream.AESCTR},
+	"AES-192-CTR":   {24, shadowstream.AESCTR},
+	"AES-256-CTR":   {32, shadowstream.AESCTR},
+	"AES-128-CFB":   {16, shadowstream.AESCFB},
+	"AES-192-CFB":   {24, shadowstream.AESCFB},
+	"AES-256-CFB":   {32, shadowstream.AESCFB},
+	"CHACHA20-IETF": {32, shadowstream.Chacha20IETF},
+	"XCHACHA20":     {32, shadowstream.Xchacha20},
+}
+
+// ListCipher returns a list of available cipher names sorted alphabetically.
+func ListCipher() []string {
+	var l []string
+	for k := range aeadList {
+		l = append(l, k)
+	}
+	for k := range streamList {
+		l = append(l, k)
+	}
+	sort.Strings(l)
+	return l
+}
+
+// PickCipher returns a Cipher of the given name. Derive key from password if given key is empty.
+func PickCipher(name string, key []byte, password string) (Cipher, error) {
+	name = strings.ToUpper(name)
+
+	switch name {
+	case "DUMMY":
+		return &dummy{}, nil
+	case "CHACHA20-IETF-POLY1305":
+		name = aeadChacha20Poly1305
+	case "XCHACHA20-IETF-POLY1305":
+		name = aeadXChacha20Poly1305
+	case "AES-128-GCM":
+		name = aeadAes128Gcm
+	case "AES-192-GCM":
+		name = aeadAes192Gcm
+	case "AES-256-GCM":
+		name = aeadAes256Gcm
+	}
+
+	if choice, ok := aeadList[name]; ok {
+		if len(key) == 0 {
+			key = Kdf(password, choice.KeySize)
+		}
+		if len(key) != choice.KeySize {
+			return nil, shadowaead.KeySizeError(choice.KeySize)
+		}
+		aead, err := choice.New(key)
+		return &AeadCipher{Cipher: aead, Key: key}, err
+	}
+
+	if choice, ok := streamList[name]; ok {
+		if len(key) == 0 {
+			key = Kdf(password, choice.KeySize)
+		}
+		if len(key) != choice.KeySize {
+			return nil, shadowstream.KeySizeError(choice.KeySize)
+		}
+		ciph, err := choice.New(key)
+		return &StreamCipher{Cipher: ciph, Key: key}, err
+	}
+
+	return nil, ErrCipherNotSupported
+}
+
+type AeadCipher struct {
+	shadowaead.Cipher
+
+	Key []byte
+}
+
+func (aead *AeadCipher) StreamConn(c net.Conn) net.Conn { return shadowaead.NewConn(c, aead) }
+func (aead *AeadCipher) PacketConn(c net.PacketConn) net.PacketConn {
+	return shadowaead.NewPacketConn(c, aead)
+}
+
+type StreamCipher struct {
+	shadowstream.Cipher
+
+	Key []byte
+}
+
+func (ciph *StreamCipher) StreamConn(c net.Conn) net.Conn { return shadowstream.NewConn(c, ciph) }
+func (ciph *StreamCipher) PacketConn(c net.PacketConn) net.PacketConn {
+	return shadowstream.NewPacketConn(c, ciph)
+}
+
+// dummy cipher does not encrypt
+
+type dummy struct{}
+
+func (dummy) StreamConn(c net.Conn) net.Conn             { return c }
+func (dummy) PacketConn(c net.PacketConn) net.PacketConn { return c }
+
+// key-derivation function from original Shadowsocks
+func Kdf(password string, keyLen int) []byte {
+	var b, prev []byte
+	h := md5.New()
+	for len(b) < keyLen {
+		h.Write(prev)
+		h.Write([]byte(password))
+		b = h.Sum(b)
+		prev = b[len(b)-h.Size():]
+		h.Reset()
+	}
+	return b[:keyLen]
+}