Direct proxy works

obfuscated2/frame.go

@@ -1,17 +1,5 @@
 package obfuscated2
 
-import (
-	"bytes"
-	"crypto/rand"
-	"encoding/binary"
-	"io"
-
-	"github.com/juju/errors"
-
-	"github.com/9seconds/mtg/mtproto"
-)
-
-// [frameOffsetFirst:frameOffsetKey:frameOffsetIV:frameOffsetMagic:frameOffsetDC:frameOffsetEnd]
 const (
 	frameLenKey   = 32
 	frameLenIV    = 16
@@ -24,98 +12,43 @@ const (
 	frameOffsetMagic = frameOffsetIV + frameLenMagic
 	frameOffsetDC    = frameOffsetMagic + frameLenDC
 
-	FrameLen = 64
+	frameLen = 64
 )
 
-// Frame represents handshake frame. Telegram sends 64 bytes of obfuscated2
-// initialization data first.
-// https://blog.susanka.eu/how-telegram-obfuscates-its-mtproto-traffic/
-type Frame []byte
-
-// Key returns AES encryption key.
-func (f Frame) Key() []byte {
-	return f[frameOffsetFirst:frameOffsetKey]
+// [frameOffsetFirst:frameOffsetKey:frameOffsetIV:frameOffsetMagic:frameOffsetDC:frameOffsetEnd]
+type Frame struct {
+	data [frameLen]byte
 }
 
-// IV returns AES encryption initialization vector
-func (f Frame) IV() []byte {
-	return f[frameOffsetKey:frameOffsetIV]
+func (f *Frame) Bytes() []byte {
+	return f.data[:]
 }
 
-// Magic returns magic bytes from last 8 bytes of frame. Telegram checks
-// for values there. If after decryption magic is not as expected,
-// connection considered as failed.
-func (f Frame) Magic() []byte {
-	return f[frameOffsetIV:frameOffsetMagic]
+func (f *Frame) Key() []byte {
+	return f.data[frameOffsetFirst:frameOffsetKey]
 }
 
-// DC returns number of datacenter IP client wants to use.
-func (f Frame) DC() (n int16) {
-	buf := bytes.NewReader(f[frameOffsetMagic:frameOffsetDC])
-	if err := binary.Read(buf, binary.LittleEndian, &n); err != nil {
-		n = 1
+func (f *Frame) IV() []byte {
+	return f.data[frameOffsetKey:frameOffsetIV]
+}
+
+func (f *Frame) Magic() []byte {
+	return f.data[frameOffsetIV:frameOffsetMagic]
+}
+
+func (f *Frame) DC() []byte {
+	return f.data[frameOffsetMagic:frameOffsetDC]
+}
+
+func (f *Frame) Unique() []byte {
+	return f.data[frameOffsetFirst:frameOffsetDC]
+}
+
+func (f *Frame) Invert() (nf Frame) {
+	nf = *f
+	for i := 0; i < frameLenKey+frameLenIV; i++ {
+		nf.data[frameOffsetFirst+i] = f.data[frameOffsetIV-1-i]
 	}
 
 	return
 }
-
-// ConnectionType identifies connection type of the handshake frame.
-func (f Frame) ConnectionType() (mtproto.ConnectionType, error) {
-	return mtproto.ConnectionTagFromHandshake(f.Magic())
-}
-
-// Invert inverts frame for extracting encryption keys. Pkease check that link:
-// https://blog.susanka.eu/how-telegram-obfuscates-its-mtproto-traffic/
-func (f Frame) Invert() Frame {
-	reversed := make(Frame, FrameLen)
-	copy(reversed, f)
-
-	for i := 0; i < frameLenKey+frameLenIV; i++ {
-		reversed[frameOffsetFirst+i] = f[frameOffsetIV-1-i]
-	}
-
-	return reversed
-}
-
-// ExtractFrame extracts exact obfuscated2 handshake frame from given reader.
-func ExtractFrame(conn io.Reader) (Frame, error) {
-	frame := make(Frame, FrameLen)
-	buf := bytes.NewBuffer(frame)
-	buf.Reset()
-
-	if _, err := io.CopyN(buf, conn, FrameLen); err != nil {
-		return nil, errors.Annotate(err, "Cannot extract obfuscated header")
-	}
-	copy(frame, buf.Bytes())
-
-	return frame, nil
-}
-
-func generateFrame(connectionType mtproto.ConnectionType) Frame {
-	frame := make(Frame, FrameLen)
-
-	for {
-		if _, err := rand.Read(frame); err != nil {
-			continue
-		}
-		if frame[0] == 0xef {
-			continue
-		}
-
-		val := (uint32(frame[3]) << 24) | (uint32(frame[2]) << 16) | (uint32(frame[1]) << 8) | uint32(frame[0])
-		if val == 0x44414548 || val == 0x54534f50 || val == 0x20544547 || val == 0x4954504f || val == 0xeeeeeeee {
-			continue
-		}
-
-		val = (uint32(frame[7]) << 24) | (uint32(frame[6]) << 16) | (uint32(frame[5]) << 8) | uint32(frame[4])
-		if val == 0x00000000 {
-			continue
-		}
-
-		// error has to be checked before calling this function
-		tag, _ := connectionType.Tag() // nolint: errcheck, gosec
-		copy(frame.Magic(), tag)
-
-		return frame
-	}
-}