/*******************************************************************************
* Copyright (c) 2014, Institute for Pervasive Computing, ETH Zurich.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Scandium (Sc) Security for Californium.
******************************************************************************/
package ch.ethz.inf.vs.scandium.dtls;
import ch.ethz.inf.vs.scandium.util.DatagramReader;
import ch.ethz.inf.vs.scandium.util.DatagramWriter;
/**
* The server send this request after receiving a {@link ClientHello} message to
* prevent Denial-of-Service Attacks. See <a
* href="http://tools.ietf.org/html/rfc6347#section-4.2.1">RFC 6347</a> for the
* definition.
*
* @author Stefan Jucker
*
*/
public class HelloVerifyRequest extends HandshakeMessage {
// DTLS-specific constants ///////////////////////////////////////////
private static final int VERSION_BITS = 8; // for major and minor each
private static final int COOKIE_LENGTH_BITS = 8;
// Members ///////////////////////////////////////////////////////////
/**
* This field will contain the lower of that suggested by the client in the
* client hello and the highest supported by the server.
*/
private ProtocolVersion serverVersion;
/** The cookie which needs to be replayed by the client. */
private Cookie cookie;
// Constructor ////////////////////////////////////////////////////
public HelloVerifyRequest(ProtocolVersion version, Cookie cookie) {
this.serverVersion = version;
this.cookie = cookie;
}
// Serialization //////////////////////////////////////////////////
@Override
public byte[] fragmentToByteArray() {
DatagramWriter writer = new DatagramWriter();
writer.write(serverVersion.getMajor(), VERSION_BITS);
writer.write(serverVersion.getMinor(), VERSION_BITS);
writer.write(cookie.length(), COOKIE_LENGTH_BITS);
writer.writeBytes(cookie.getCookie());
return writer.toByteArray();
}
public static HandshakeMessage fromByteArray(byte[] byteArray) {
DatagramReader reader = new DatagramReader(byteArray);
int major = reader.read(VERSION_BITS);
int minor = reader.read(VERSION_BITS);
ProtocolVersion version = new ProtocolVersion(major, minor);
int cookieLength = reader.read(COOKIE_LENGTH_BITS);
Cookie cookie = new Cookie(reader.readBytes(cookieLength));
return new HelloVerifyRequest(version, cookie);
}
// Methods ////////////////////////////////////////////////////////
@Override
public HandshakeType getMessageType() {
return HandshakeType.HELLO_VERIFY_REQUEST;
}
@Override
public int getMessageLength() {
// fixed: version (2) + cookie length (1)
return 3 + cookie.length();
}
public ProtocolVersion getServerVersion() {
return serverVersion;
}
public Cookie getCookie() {
return cookie;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append(super.toString());
sb.append("\t\tServer Version: " + serverVersion.getMajor() + ", " + serverVersion.getMinor() + "\n");
sb.append("\t\tCookie Length: " + cookie.length() + "\n");
sb.append("\t\tCookie: " + ByteArrayUtils.toHexString(cookie.getCookie()) + "\n");
return sb.toString();
}
}