添加 github.com/pion/dtls 代码

dtls-2.0.9/pkg/protocol/handshake/message_hello_verify_request.go

@@ -0,0 +1,62 @@
+package handshake
+
+import (
+	"github.com/pion/dtls/v2/pkg/protocol"
+)
+
+// MessageHelloVerifyRequest is as follows:
+//
+//   struct {
+//     ProtocolVersion server_version;
+//     opaque cookie<0..2^8-1>;
+//   } HelloVerifyRequest;
+//
+//   The HelloVerifyRequest message type is hello_verify_request(3).
+//
+//   When the client sends its ClientHello message to the server, the server
+//   MAY respond with a HelloVerifyRequest message.  This message contains
+//   a stateless cookie generated using the technique of [PHOTURIS].  The
+//   client MUST retransmit the ClientHello with the cookie added.
+//
+//   https://tools.ietf.org/html/rfc6347#section-4.2.1
+type MessageHelloVerifyRequest struct {
+	Version protocol.Version
+	Cookie  []byte
+}
+
+// Type returns the Handshake Type
+func (m MessageHelloVerifyRequest) Type() Type {
+	return TypeHelloVerifyRequest
+}
+
+// Marshal encodes the Handshake
+func (m *MessageHelloVerifyRequest) Marshal() ([]byte, error) {
+	if len(m.Cookie) > 255 {
+		return nil, errCookieTooLong
+	}
+
+	out := make([]byte, 3+len(m.Cookie))
+	out[0] = m.Version.Major
+	out[1] = m.Version.Minor
+	out[2] = byte(len(m.Cookie))
+	copy(out[3:], m.Cookie)
+
+	return out, nil
+}
+
+// Unmarshal populates the message from encoded data
+func (m *MessageHelloVerifyRequest) Unmarshal(data []byte) error {
+	if len(data) < 3 {
+		return errBufferTooSmall
+	}
+	m.Version.Major = data[0]
+	m.Version.Minor = data[1]
+	cookieLength := data[2]
+	if len(data) < (int(cookieLength) + 3) {
+		return errBufferTooSmall
+	}
+	m.Cookie = make([]byte, cookieLength)
+
+	copy(m.Cookie, data[3:3+cookieLength])
+	return nil
+}