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@@ -0,0 +1,200 @@
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+package obfs
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+
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+import (
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+ "bytes"
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+ "encoding/binary"
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+ "io"
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+ "math/rand"
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+ "net"
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+ "time"
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+
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+ B "github.com/sagernet/sing/common/buf"
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+)
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+
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+func init() {
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+ rand.Seed(time.Now().Unix())
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+}
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+
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+const (
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+ chunkSize = 1 << 14 // 2 ** 14 == 16 * 1024
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+)
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+
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+// TLSObfs is shadowsocks tls simple-obfs implementation
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+type TLSObfs struct {
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+ net.Conn
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+ server string
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+ remain int
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+ firstRequest bool
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+ firstResponse bool
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+}
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+
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+func (to *TLSObfs) read(b []byte, discardN int) (int, error) {
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+ buf := B.Get(discardN)
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+ _, err := io.ReadFull(to.Conn, buf)
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+ if err != nil {
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+ return 0, err
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+ }
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+ B.Put(buf)
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+
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+ sizeBuf := make([]byte, 2)
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+ _, err = io.ReadFull(to.Conn, sizeBuf)
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+ if err != nil {
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+ return 0, nil
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+ }
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+
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+ length := int(binary.BigEndian.Uint16(sizeBuf))
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+ if length > len(b) {
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+ n, err := to.Conn.Read(b)
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+ if err != nil {
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+ return n, err
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+ }
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+ to.remain = length - n
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+ return n, nil
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+ }
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+
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+ return io.ReadFull(to.Conn, b[:length])
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+}
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+
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+func (to *TLSObfs) Read(b []byte) (int, error) {
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+ if to.remain > 0 {
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+ length := to.remain
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+ if length > len(b) {
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+ length = len(b)
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+ }
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+
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+ n, err := io.ReadFull(to.Conn, b[:length])
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+ to.remain -= n
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+ return n, err
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+ }
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+
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+ if to.firstResponse {
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+ // type + ver + lensize + 91 = 96
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+ // type + ver + lensize + 1 = 6
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+ // type + ver = 3
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+ to.firstResponse = false
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+ return to.read(b, 105)
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+ }
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+
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+ // type + ver = 3
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+ return to.read(b, 3)
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+}
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+
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+func (to *TLSObfs) Write(b []byte) (int, error) {
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+ length := len(b)
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+ for i := 0; i < length; i += chunkSize {
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+ end := i + chunkSize
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+ if end > length {
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+ end = length
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+ }
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+
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+ n, err := to.write(b[i:end])
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+ if err != nil {
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+ return n, err
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+ }
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+ }
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+ return length, nil
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+}
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+
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+func (to *TLSObfs) write(b []byte) (int, error) {
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+ if to.firstRequest {
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+ helloMsg := makeClientHelloMsg(b, to.server)
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+ _, err := to.Conn.Write(helloMsg)
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+ to.firstRequest = false
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+ return len(b), err
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+ }
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+
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+ buf := B.NewSize(5 + len(b))
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+ defer buf.Release()
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+ buf.Write([]byte{0x17, 0x03, 0x03})
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+ binary.Write(buf, binary.BigEndian, uint16(len(b)))
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+ buf.Write(b)
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+ _, err := to.Conn.Write(buf.Bytes())
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+ return len(b), err
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+}
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+
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+// NewTLSObfs return a SimpleObfs
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+func NewTLSObfs(conn net.Conn, server string) net.Conn {
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+ return &TLSObfs{
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+ Conn: conn,
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+ server: server,
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+ firstRequest: true,
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+ firstResponse: true,
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+ }
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+}
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+
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+func makeClientHelloMsg(data []byte, server string) []byte {
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+ random := make([]byte, 28)
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+ sessionID := make([]byte, 32)
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+ rand.Read(random)
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+ rand.Read(sessionID)
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+
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+ buf := &bytes.Buffer{}
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+
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+ // handshake, TLS 1.0 version, length
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+ buf.WriteByte(22)
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+ buf.Write([]byte{0x03, 0x01})
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+ length := uint16(212 + len(data) + len(server))
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+ buf.WriteByte(byte(length >> 8))
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+ buf.WriteByte(byte(length & 0xff))
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+
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+ // clientHello, length, TLS 1.2 version
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+ buf.WriteByte(1)
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+ buf.WriteByte(0)
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+ binary.Write(buf, binary.BigEndian, uint16(208+len(data)+len(server)))
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+ buf.Write([]byte{0x03, 0x03})
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+
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+ // random with timestamp, sid len, sid
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+ binary.Write(buf, binary.BigEndian, uint32(time.Now().Unix()))
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+ buf.Write(random)
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+ buf.WriteByte(32)
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+ buf.Write(sessionID)
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+
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+ // cipher suites
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+ buf.Write([]byte{0x00, 0x38})
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+ buf.Write([]byte{
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+ 0xc0, 0x2c, 0xc0, 0x30, 0x00, 0x9f, 0xcc, 0xa9, 0xcc, 0xa8, 0xcc, 0xaa, 0xc0, 0x2b, 0xc0, 0x2f,
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+ 0x00, 0x9e, 0xc0, 0x24, 0xc0, 0x28, 0x00, 0x6b, 0xc0, 0x23, 0xc0, 0x27, 0x00, 0x67, 0xc0, 0x0a,
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+ 0xc0, 0x14, 0x00, 0x39, 0xc0, 0x09, 0xc0, 0x13, 0x00, 0x33, 0x00, 0x9d, 0x00, 0x9c, 0x00, 0x3d,
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+ 0x00, 0x3c, 0x00, 0x35, 0x00, 0x2f, 0x00, 0xff,
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+ })
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+
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+ // compression
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+ buf.Write([]byte{0x01, 0x00})
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+
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+ // extension length
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+ binary.Write(buf, binary.BigEndian, uint16(79+len(data)+len(server)))
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+
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+ // session ticket
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+ buf.Write([]byte{0x00, 0x23})
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+ binary.Write(buf, binary.BigEndian, uint16(len(data)))
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+ buf.Write(data)
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+
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+ // server name
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+ buf.Write([]byte{0x00, 0x00})
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+ binary.Write(buf, binary.BigEndian, uint16(len(server)+5))
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+ binary.Write(buf, binary.BigEndian, uint16(len(server)+3))
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+ buf.WriteByte(0)
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+ binary.Write(buf, binary.BigEndian, uint16(len(server)))
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+ buf.Write([]byte(server))
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+
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+ // ec_point
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+ buf.Write([]byte{0x00, 0x0b, 0x00, 0x04, 0x03, 0x01, 0x00, 0x02})
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+
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+ // groups
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+ buf.Write([]byte{0x00, 0x0a, 0x00, 0x0a, 0x00, 0x08, 0x00, 0x1d, 0x00, 0x17, 0x00, 0x19, 0x00, 0x18})
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+
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+ // signature
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+ buf.Write([]byte{
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+ 0x00, 0x0d, 0x00, 0x20, 0x00, 0x1e, 0x06, 0x01, 0x06, 0x02, 0x06, 0x03, 0x05,
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+ 0x01, 0x05, 0x02, 0x05, 0x03, 0x04, 0x01, 0x04, 0x02, 0x04, 0x03, 0x03, 0x01,
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+ 0x03, 0x02, 0x03, 0x03, 0x02, 0x01, 0x02, 0x02, 0x02, 0x03,
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+ })
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+
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+ // encrypt then mac
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+ buf.Write([]byte{0x00, 0x16, 0x00, 0x00})
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+
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+ // extended master secret
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+ buf.Write([]byte{0x00, 0x17, 0x00, 0x00})
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+
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+ return buf.Bytes()
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+}
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