Success path for fake tls is implemented

tlstypes/client_hello.go

@@ -0,0 +1,86 @@
+package tlstypes
+
+import (
+	"bytes"
+	"crypto/hmac"
+	"crypto/sha256"
+	"fmt"
+
+	"github.com/9seconds/mtg/config"
+	"github.com/9seconds/mtg/utils"
+)
+
+type ClientHello struct {
+	Handshake
+}
+
+func (c ClientHello) Digest() []byte {
+	dirtyDigest := c.Random
+	c.Random = [32]byte{}
+
+	rec := Record{
+		Type:    RecordTypeHandshake,
+		Version: Version10,
+		Data:    &c,
+	}
+
+	mac := hmac.New(sha256.New, config.C.Secret)
+	mac.Write(rec.Bytes()) // nolint: errcheck
+	computedDigest := mac.Sum(nil)
+
+	for i := range computedDigest {
+		computedDigest[i] ^= dirtyDigest[i]
+	}
+
+	return computedDigest
+}
+
+func ParseClientHello(raw []byte) (*ClientHello, error) {
+	rv := &ClientHello{}
+
+	rv.Type = HandshakeType(raw[0])
+	if rv.Type != HandshakeTypeClient {
+		return nil, fmt.Errorf("incorrect handshake type %v", rv.Type)
+	}
+
+	raw = raw[1:]
+	sizeUint24 := utils.Uint24{}
+	copy(sizeUint24[:], utils.ReverseBytes(raw[:3]))
+	size := int(utils.FromUint24(sizeUint24))
+
+	raw = raw[3:]
+	if len(raw) != size {
+		return nil, fmt.Errorf("payload size mismatch (%d != %d)", len(raw), size)
+	}
+
+	versionRaw := raw[:2]
+
+	switch {
+	case bytes.Equal(versionRaw, Version13Bytes):
+		rv.Version = Version13
+	case bytes.Equal(versionRaw, Version12Bytes):
+		rv.Version = Version12
+	case bytes.Equal(versionRaw, Version11Bytes):
+		rv.Version = Version11
+	case bytes.Equal(versionRaw, Version10Bytes):
+		rv.Version = Version10
+	default:
+		return nil, fmt.Errorf("unknown protocol version %v", versionRaw)
+	}
+
+	raw = raw[2:]
+	copy(rv.Random[:], raw[:32])
+	raw = raw[32:]
+
+	sessionIDLength := int(raw[0])
+	raw = raw[1:]
+	rv.SessionID = make([]byte, sessionIDLength)
+	copy(rv.SessionID, raw)
+	raw = raw[sessionIDLength:]
+
+	tail := make([]byte, len(raw))
+	copy(tail, raw)
+	rv.Tail = RawBytes(tail)
+
+	return rv, nil
+}