添加 github.com/pion/dtls 代码

dtls-2.0.9/pkg/protocol/change_cipher_spec.go

@@ -0,0 +1,28 @@
+package protocol
+
+// ChangeCipherSpec protocol exists to signal transitions in
+// ciphering strategies.  The protocol consists of a single message,
+// which is encrypted and compressed under the current (not the pending)
+// connection state.  The message consists of a single byte of value 1.
+// https://tools.ietf.org/html/rfc5246#section-7.1
+type ChangeCipherSpec struct {
+}
+
+// ContentType returns the ContentType of this content
+func (c ChangeCipherSpec) ContentType() ContentType {
+	return ContentTypeChangeCipherSpec
+}
+
+// Marshal encodes the ChangeCipherSpec to binary
+func (c *ChangeCipherSpec) Marshal() ([]byte, error) {
+	return []byte{0x01}, nil
+}
+
+// Unmarshal populates the ChangeCipherSpec from binary
+func (c *ChangeCipherSpec) Unmarshal(data []byte) error {
+	if len(data) == 1 && data[0] == 0x01 {
+		return nil
+	}
+
+	return errInvalidCipherSpec
+}