diff --git a/mtglib/internal/obfuscated2/client_handshake.go b/mtglib/internal/obfuscated2/client_handshake.go new file mode 100644 index 0000000..275afb0 --- /dev/null +++ b/mtglib/internal/obfuscated2/client_handshake.go @@ -0,0 +1,37 @@ +package obfuscated2 + +import ( + "crypto/cipher" + "crypto/subtle" + "encoding/hex" + "fmt" +) + +// Connection Type secure. We support only fake tls. +var clientHandshakeMagic = []byte{0xdd, 0xdd, 0xdd, 0xdd} + +func ClientHandshake(secret []byte, handshakeFrame *HandhakeFrame) (int16, cipher.Stream, cipher.Stream, error) { + decHasher := acquireSha256Hasher() + defer releaseSha256Hasher(decHasher) + + decHasher.Write(handshakeFrame.key()) // nolint: errcheck + decHasher.Write(secret) // nolint: errcheck + decryptor := makeAesCtr(decHasher.Sum(nil), handshakeFrame.iv()) + + encHasher := acquireSha256Hasher() + defer releaseSha256Hasher(encHasher) + + invertedFrame := handshakeFrame.invert() + encHasher.Write(invertedFrame.key()) // nolint: errcheck + encHasher.Write(secret) // nolint: errcheck + encryptor := makeAesCtr(encHasher.Sum(nil), invertedFrame.iv()) + + decryptedFrame := HandhakeFrame{} + decryptor.XORKeyStream(decryptedFrame.data[:], handshakeFrame.data[:]) + + if magic := decryptedFrame.magic(); subtle.ConstantTimeCompare(clientHandshakeMagic, magic) != 1 { + return 0, nil, nil, fmt.Errorf("unsupported connection type: %s", hex.EncodeToString(magic)) + } + + return decryptedFrame.dc(), encryptor, decryptor, nil +} diff --git a/mtglib/internal/obfuscated2/conn.go b/mtglib/internal/obfuscated2/conn.go new file mode 100644 index 0000000..dbd69ed --- /dev/null +++ b/mtglib/internal/obfuscated2/conn.go @@ -0,0 +1,33 @@ +package obfuscated2 + +import ( + "crypto/cipher" + "net" +) + +type Conn struct { + net.Conn + + Encryptor cipher.Stream + Decryptor cipher.Stream + + writeBuf []byte +} + +func (c *Conn) Read(p []byte) (int, error) { + n, err := c.Conn.Read(p) + if err != nil { + return n, err // nolint: wrapcheck + } + + c.Decryptor.XORKeyStream(p, p[:n]) + + return n, nil +} + +func (c *Conn) Write(p []byte) (int, error) { + c.writeBuf = append(c.writeBuf[:0], p...) + c.Encryptor.XORKeyStream(c.writeBuf, c.writeBuf) + + return c.Conn.Write(c.writeBuf) +} diff --git a/mtglib/internal/obfuscated2/frame.go b/mtglib/internal/obfuscated2/frame.go index 07570d8..0526972 100644 --- a/mtglib/internal/obfuscated2/frame.go +++ b/mtglib/internal/obfuscated2/frame.go @@ -1 +1,79 @@ package obfuscated2 + +import ( + "encoding/binary" + "fmt" + "io" +) + +const ( + handshakeFrameLen = 64 + + handshakeFrameLenKey = 32 + handshakeFrameLenIV = 16 + handshakeFrameLenMagic = 4 + handshakeFrameLenDC = 2 + + handshakeFrameOffsetStart = 8 + handshakeFrameOffsetKey = handshakeFrameOffsetStart + handshakeFrameOffsetIV = handshakeFrameOffsetKey + handshakeFrameLenKey + handshakeFrameOffsetMagic = handshakeFrameOffsetIV + handshakeFrameLenIV + handshakeFrameOffsetDC = handshakeFrameOffsetMagic + handshakeFrameLenMagic + handshakeFrameOffsetEnd = handshakeFrameOffsetDC + handshakeFrameLenDC +) + +// A structure of obfuscated2 handshake frame is following: +// +// [frameOffsetFirst:frameOffsetKey:frameOffsetIV:frameOffsetMagic:frameOffsetDC:frameOffsetEnd]. +// +// - 8 bytes of noise +// - 32 bytes of AES Key +// - 16 bytes of AES IV +// - 4 bytes of 'magic' - this has some settings like a connection type +// - 2 bytes of 'DC'. DC is little endian int16 +// - 2 bytes of noise +type HandhakeFrame struct { + data [handshakeFrameLen]byte +} + +func (f *HandhakeFrame) Fingerprint() []byte { + return f.data[handshakeFrameOffsetStart:handshakeFrameOffsetEnd] +} + +func (f *HandhakeFrame) dc() int16 { + data := f.data[handshakeFrameOffsetDC:handshakeFrameOffsetEnd] + + return int16(binary.LittleEndian.Uint16(data)) +} + +func (f *HandhakeFrame) key() []byte { + return f.data[handshakeFrameLenKey:handshakeFrameOffsetIV] +} + +func (f *HandhakeFrame) iv() []byte { + return f.data[handshakeFrameOffsetIV:handshakeFrameOffsetMagic] +} + +func (f *HandhakeFrame) magic() []byte { + return f.data[handshakeFrameOffsetMagic:handshakeFrameOffsetDC] +} + +func (f *HandhakeFrame) invert() *HandhakeFrame { + newFrame := &HandhakeFrame{} + + for i, v := range f.data { + newFrame.data[handshakeFrameLen-1-i] = v + } + + return newFrame +} + +func ReadHandshakeFrame(reader io.Reader) (*HandhakeFrame, error) { + frame := &HandhakeFrame{} + + if _, err := io.ReadFull(reader, frame.data[:]); err != nil { + return nil, fmt.Errorf("cannot read frame data: %w", err) + } + + return frame, nil +} diff --git a/mtglib/internal/obfuscated2/pools.go b/mtglib/internal/obfuscated2/pools.go new file mode 100644 index 0000000..ce3204f --- /dev/null +++ b/mtglib/internal/obfuscated2/pools.go @@ -0,0 +1,22 @@ +package obfuscated2 + +import ( + "crypto/sha256" + "hash" + "sync" +) + +var sha256HasherPool = sync.Pool{ + New: func() interface{} { + return sha256.New() + }, +} + +func acquireSha256Hasher() hash.Hash { + return sha256HasherPool.Get().(hash.Hash) +} + +func releaseSha256Hasher(h hash.Hash) { + h.Reset() + sha256HasherPool.Put(h) +} diff --git a/mtglib/internal/obfuscated2/utils.go b/mtglib/internal/obfuscated2/utils.go new file mode 100644 index 0000000..a3fdcf9 --- /dev/null +++ b/mtglib/internal/obfuscated2/utils.go @@ -0,0 +1,15 @@ +package obfuscated2 + +import ( + "crypto/aes" + "crypto/cipher" +) + +func makeAesCtr(key, iv []byte) cipher.Stream { + block, err := aes.NewCipher(key) + if err != nil { + panic(err) + } + + return cipher.NewCTR(block, iv) +} diff --git a/mtglib/proxy.go b/mtglib/proxy.go index 90adaa2..3c3bad2 100644 --- a/mtglib/proxy.go +++ b/mtglib/proxy.go @@ -8,6 +8,7 @@ import ( "sync" "time" + "github.com/9seconds/mtg/v2/mtglib/internal/obfuscated2" "github.com/panjf2000/ants/v2" ) @@ -17,13 +18,12 @@ type Proxy struct { streamWaitGroup sync.WaitGroup workerPool *ants.PoolWithFunc - secret Secret - network Network - timeAttackDetector TimeAttackDetector - antiReplayCache AntiReplayCache - ipBlocklist IPBlocklist - eventStream EventStream - logger Logger + secret Secret + network Network + antiReplayCache AntiReplayCache + ipBlocklist IPBlocklist + eventStream EventStream + logger Logger } func (p *Proxy) ServeConn(conn net.Conn) { @@ -49,6 +49,12 @@ func (p *Proxy) ServeConn(conn net.Conn) { }) ctx.logger.Info("Stream has been finished") }() + + if err := p.doObfuscated2Handshake(ctx); err != nil { + p.logger.InfoError("obfuscated2 handshake is failed", err) + + return + } } func (p *Proxy) Serve(listener net.Listener) error { @@ -88,6 +94,32 @@ func (p *Proxy) Shutdown() { p.workerPool.Release() } +func (p *Proxy) doObfuscated2Handshake(ctx *streamContext) error { + handshakeFrame, err := obfuscated2.ReadHandshakeFrame(ctx.clientConn) + if err != nil { + return fmt.Errorf("cannot read handshake frame: %w", err) + } + + dc, encryptor, decryptor, err := obfuscated2.ClientHandshake(p.secret.Key[:], handshakeFrame) + if err != nil { + return fmt.Errorf("cannot process client handshake: %w", err) + } + + if dc < 0 { + dc = -dc + } + + ctx.dc = int(dc) + ctx.logger = ctx.logger.BindInt("dc", ctx.dc) + ctx.clientConn = &obfuscated2.Conn{ + Conn: ctx.clientConn, + Encryptor: encryptor, + Decryptor: decryptor, + } + + return nil +} + func NewProxy(opts ProxyOpts) (*Proxy, error) { switch { case opts.Network == nil: diff --git a/mtglib/stream_context.go b/mtglib/stream_context.go index cd5d1e8..1c75482 100644 --- a/mtglib/stream_context.go +++ b/mtglib/stream_context.go @@ -13,6 +13,7 @@ type streamContext struct { ctxCancel context.CancelFunc clientConn net.Conn connID string + dc int logger Logger }