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// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
// SPDX-License-Identifier: MIT
package handshake
import (
"github.com/pion/dtls/v3/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 := int(data[2])
if len(data) < cookieLength+3 {
return errBufferTooSmall
}
m.Cookie = make([]byte, cookieLength)
copy(m.Cookie, data[3:3+cookieLength])
return nil
}
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