Reworked base

newobfuscated2/client_protocol.go

@@ -0,0 +1,95 @@
+package newobfuscated2
+
+import (
+	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/sha256"
+	"encoding/binary"
+	"io"
+	"time"
+
+	"github.com/juju/errors"
+
+	"github.com/9seconds/mtg/newantireplay"
+	"github.com/9seconds/mtg/newconfig"
+	"github.com/9seconds/mtg/newprotocol"
+	"github.com/9seconds/mtg/newwrappers"
+)
+
+const clientProtocolHandshakeTimeout = 10 * time.Second
+
+type ClientProtocol struct {
+	newprotocol.BaseProtocol
+}
+
+func (c *ClientProtocol) Handshake(socket newwrappers.StreamReadWriteCloser) (newwrappers.StreamReadWriteCloser, error) {
+	fm, err := c.ReadFrame(socket)
+	if err != nil {
+		return nil, errors.Annotate(err, "Cannot make client handshake")
+	}
+
+	decHasher := sha256.New()
+	decHasher.Write(fm.key())           // nolint: errcheck
+	decHasher.Write(newconfig.C.Secret) // nolint: errcheck
+	decryptor := makeStreamCipher(decHasher.Sum(nil), fm.iv())
+
+	invertedFrame := fm.invert()
+	encHasher := sha256.New()
+	encHasher.Write(invertedFrame.key()) // nolint: errcheck
+	encHasher.Write(newconfig.C.Secret)  // nolint: errcheck
+	encryptor := makeStreamCipher(encHasher.Sum(nil), invertedFrame.iv())
+
+	decryptedFrame := frame{}
+	decryptor.XORKeyStream(decryptedFrame.bytes(), fm.bytes())
+
+	magic := decryptedFrame.magic()
+	switch {
+	case bytes.Equal(magic, newprotocol.ConnectionTagAbridged):
+		c.ConnectionType = newprotocol.ConnectionTypeAbridged
+	case bytes.Equal(magic, newprotocol.ConnectionTagIntermediate):
+		c.ConnectionType = newprotocol.ConnectionTypeIntermediate
+	case bytes.Equal(magic, newprotocol.ConnectionTagSecure):
+		c.ConnectionType = newprotocol.ConnectionTypeSecure
+	default:
+		return nil, errors.New("Unknown connection type")
+	}
+
+	c.ConnectionProtocol = newprotocol.ConnectionProtocolIPv4
+	if socket.LocalAddr().IP.To4() == nil {
+		c.ConnectionProtocol = newprotocol.ConnectionProtocolIPv6
+	}
+
+	buf := bytes.NewReader(decryptedFrame.dc())
+	if err := binary.Read(buf, binary.LittleEndian, &c.DC); err != nil {
+		c.DC = 1
+	}
+
+	antiReplayKey := decryptedFrame.unique()
+	if newantireplay.Has(antiReplayKey) {
+		return nil, errors.New("Replay attack is detected")
+	}
+	newantireplay.Add(antiReplayKey)
+
+	return newwrappers.NewObfuscated2(socket, encryptor, decryptor), nil
+}
+
+func (c *ClientProtocol) ReadFrame(socket newwrappers.StreamReader) (fm frame, err error) {
+	if _, err := io.ReadFull(handshakeReader{socket}, fm.bytes()); err != nil {
+		err = errors.Annotate(err, "Cannot extract obfuscated2 frame")
+	}
+	return
+}
+
+type handshakeReader struct {
+	parent newwrappers.StreamReader
+}
+
+func (h handshakeReader) Read(p []byte) (int, error) {
+	return h.parent.ReadTimeout(p, clientProtocolHandshakeTimeout)
+}
+
+func makeStreamCipher(key, iv []byte) cipher.Stream {
+	block, _ := aes.NewCipher(key) // nolint: gosec
+	return cipher.NewCTR(block, iv)
+}