package obfs import ( "bytes" "encoding/binary" "io" "math/rand" "net" "time" B "github.com/sagernet/sing/common/buf" "github.com/sagernet/sing/common/random" ) func init() { random.InitializeSeed() } const ( chunkSize = 1 << 14 // 2 ** 14 == 16 * 1024 ) // TLSObfs is shadowsocks tls simple-obfs implementation type TLSObfs struct { net.Conn server string remain int firstRequest bool firstResponse bool } func (to *TLSObfs) read(b []byte, discardN int) (int, error) { buf := B.Get(discardN) _, err := io.ReadFull(to.Conn, buf) B.Put(buf) if err != nil { return 0, err } sizeBuf := make([]byte, 2) _, err = io.ReadFull(to.Conn, sizeBuf) if err != nil { return 0, nil } length := int(binary.BigEndian.Uint16(sizeBuf)) if length > len(b) { n, err := to.Conn.Read(b) if err != nil { return n, err } to.remain = length - n return n, nil } return io.ReadFull(to.Conn, b[:length]) } func (to *TLSObfs) Read(b []byte) (int, error) { if to.remain > 0 { length := to.remain if length > len(b) { length = len(b) } n, err := io.ReadFull(to.Conn, b[:length]) to.remain -= n return n, err } if to.firstResponse { // type + ver + lensize + 91 = 96 // type + ver + lensize + 1 = 6 // type + ver = 3 to.firstResponse = false return to.read(b, 105) } // type + ver = 3 return to.read(b, 3) } func (to *TLSObfs) Write(b []byte) (int, error) { length := len(b) for i := 0; i < length; i += chunkSize { end := i + chunkSize if end > length { end = length } n, err := to.write(b[i:end]) if err != nil { return n, err } } return length, nil } func (to *TLSObfs) write(b []byte) (int, error) { if to.firstRequest { helloMsg := makeClientHelloMsg(b, to.server) _, err := to.Conn.Write(helloMsg) to.firstRequest = false return len(b), err } buf := B.NewSize(5 + len(b)) defer buf.Release() buf.Write([]byte{0x17, 0x03, 0x03}) binary.Write(buf, binary.BigEndian, uint16(len(b))) buf.Write(b) _, err := to.Conn.Write(buf.Bytes()) return len(b), err } // NewTLSObfs return a SimpleObfs func NewTLSObfs(conn net.Conn, server string) net.Conn { return &TLSObfs{ Conn: conn, server: server, firstRequest: true, firstResponse: true, } } func makeClientHelloMsg(data []byte, server string) []byte { random := make([]byte, 28) sessionID := make([]byte, 32) rand.Read(random) rand.Read(sessionID) buf := &bytes.Buffer{} // handshake, TLS 1.0 version, length buf.WriteByte(22) buf.Write([]byte{0x03, 0x01}) length := uint16(212 + len(data) + len(server)) buf.WriteByte(byte(length >> 8)) buf.WriteByte(byte(length & 0xff)) // clientHello, length, TLS 1.2 version buf.WriteByte(1) buf.WriteByte(0) binary.Write(buf, binary.BigEndian, uint16(208+len(data)+len(server))) buf.Write([]byte{0x03, 0x03}) // random with timestamp, sid len, sid binary.Write(buf, binary.BigEndian, uint32(time.Now().Unix())) buf.Write(random) buf.WriteByte(32) buf.Write(sessionID) // cipher suites buf.Write([]byte{0x00, 0x38}) buf.Write([]byte{ 0xc0, 0x2c, 0xc0, 0x30, 0x00, 0x9f, 0xcc, 0xa9, 0xcc, 0xa8, 0xcc, 0xaa, 0xc0, 0x2b, 0xc0, 0x2f, 0x00, 0x9e, 0xc0, 0x24, 0xc0, 0x28, 0x00, 0x6b, 0xc0, 0x23, 0xc0, 0x27, 0x00, 0x67, 0xc0, 0x0a, 0xc0, 0x14, 0x00, 0x39, 0xc0, 0x09, 0xc0, 0x13, 0x00, 0x33, 0x00, 0x9d, 0x00, 0x9c, 0x00, 0x3d, 0x00, 0x3c, 0x00, 0x35, 0x00, 0x2f, 0x00, 0xff, }) // compression buf.Write([]byte{0x01, 0x00}) // extension length binary.Write(buf, binary.BigEndian, uint16(79+len(data)+len(server))) // session ticket buf.Write([]byte{0x00, 0x23}) binary.Write(buf, binary.BigEndian, uint16(len(data))) buf.Write(data) // server name buf.Write([]byte{0x00, 0x00}) binary.Write(buf, binary.BigEndian, uint16(len(server)+5)) binary.Write(buf, binary.BigEndian, uint16(len(server)+3)) buf.WriteByte(0) binary.Write(buf, binary.BigEndian, uint16(len(server))) buf.Write([]byte(server)) // ec_point buf.Write([]byte{0x00, 0x0b, 0x00, 0x04, 0x03, 0x01, 0x00, 0x02}) // groups buf.Write([]byte{0x00, 0x0a, 0x00, 0x0a, 0x00, 0x08, 0x00, 0x1d, 0x00, 0x17, 0x00, 0x19, 0x00, 0x18}) // signature buf.Write([]byte{ 0x00, 0x0d, 0x00, 0x20, 0x00, 0x1e, 0x06, 0x01, 0x06, 0x02, 0x06, 0x03, 0x05, 0x01, 0x05, 0x02, 0x05, 0x03, 0x04, 0x01, 0x04, 0x02, 0x04, 0x03, 0x03, 0x01, 0x03, 0x02, 0x03, 0x03, 0x02, 0x01, 0x02, 0x02, 0x02, 0x03, }) // encrypt then mac buf.Write([]byte{0x00, 0x16, 0x00, 0x00}) // extended master secret buf.Write([]byte{0x00, 0x17, 0x00, 0x00}) return buf.Bytes() }