init

shadow/tls_util.go

@@ -0,0 +1,87 @@
+package shadow
+
+import (
+	"encoding/binary"
+)
+
+const (
+	RecordHeaderLen = 5
+
+	ChangeCipherSpec = 0x14
+	EncryptedAlert   = 0x15
+	Handshake        = 0x16
+	AppData          = 0x17
+
+	VersionTLS10 = 0x0301
+	VersionTLS11 = 0x0302
+	VersionTLS12 = 0x0303
+	VersionTLS13 = 0x0304
+
+	ServerHello = 2
+	ClientHello = 1
+)
+
+type TLSHeader struct {
+	Type          uint8
+	Version       uint16
+	Length        int
+	HandshakeType uint8
+}
+
+func (t *TLSHeader) toString() string {
+	if t == nil {
+		return "nul"
+	}
+	desc := ""
+	switch t.Type {
+	case Handshake:
+		desc += "Type=handshake;"
+		switch t.HandshakeType {
+		case ClientHello:
+			desc += "HandshakeType=ClientHello;"
+			break
+		case ServerHello:
+			desc += "HandshakeType=ServerHello;"
+			break
+		}
+		break
+	case ChangeCipherSpec:
+		desc += "Type=ChangeCipherSpec;"
+		break
+	case EncryptedAlert:
+		desc += "Type=EncryptedAlert;"
+		break
+	case AppData:
+		desc += "Type=AppData;"
+		break
+	}
+	return desc
+}
+
+func ParseAndVerifyTLSHeader(data []byte) *TLSHeader {
+	if len(data) < RecordHeaderLen {
+		return nil
+	}
+	header := &TLSHeader{
+		Type:    data[0],
+		Version: binary.BigEndian.Uint16(data[1:3]),
+		Length:  int(binary.BigEndian.Uint16(data[3:5])),
+	}
+	//Check type
+	if header.Type != Handshake && header.Type != AppData && header.Type != EncryptedAlert && header.Type != ChangeCipherSpec {
+		return nil
+	}
+	//Check version
+	if header.Version != VersionTLS10 && header.Version != VersionTLS11 && header.Version != VersionTLS12 && header.Version != VersionTLS13 {
+		return nil
+	}
+
+	if header.Type == Handshake {
+		header.HandshakeType = data[5]
+		//Check Handshake type
+		if header.HandshakeType != ServerHello && header.HandshakeType != ClientHello {
+			return nil
+		}
+	}
+	return header
+}