/*******************************************************************************
* 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 java.util.ArrayList;
import java.util.List;
import ch.ethz.inf.vs.scandium.dtls.HelloExtensions.ExtensionType;
import ch.ethz.inf.vs.scandium.util.DatagramWriter;
/**
* This represents the Certificate Type Extension. See <a
* href="http://tools.ietf.org/html/draft-ietf-tls-oob-pubkey-03">Draft</a> for
* details.
*
* @author Stefan Jucker
*
*/
public abstract class CertificateTypeExtension extends HelloExtension {
// DTLS-specific constants ////////////////////////////////////////
protected static final int LIST_FIELD_LENGTH_BITS = 8;
protected static final int EXTENSION_TYPE_BITS = 8;
// Members ////////////////////////////////////////////////////////
/**
* Indicates whether this extension belongs to a client or a server. This
* has an impact upon the message format. See <a href=
* "http://tools.ietf.org/html/draft-ietf-tls-oob-pubkey-03#section-3.1"
* >CertificateTypeExtension</a> definition.
*/
private boolean isClientExtension;
/**
* For the client: a list of certificate types the client supports, sorted
* by client preference.<br />
* For the server: the certificate selected by the server out of the
* client's list.
*/
protected List<CertificateType> certificateTypes;
// Constructors ///////////////////////////////////////////////////
/**
* Constructs an empty certificate type extension. If it is client-sided
* there is a list of supported certificate type (ordered by preference);
* server-side only 1 certificate type is chosen.
*
* @param type
* the type of the extension.
* @param isClient
* whether this instance is considered the client.
*/
public CertificateTypeExtension(ExtensionType type, boolean isClient) {
super(type);
this.isClientExtension = isClient;
this.certificateTypes = new ArrayList<CertificateType>();
}
/**
* Constructs a certificate type extension with a list of supported
* certificate types. The server only chooses 1 certificate type.
*
* @param type
* the type of the extension.
* @param isClient
* whether this instance is considered the client.
* @param certificateTypes
* the list of supported certificate types.
*/
public CertificateTypeExtension(ExtensionType type, boolean isClient, List<CertificateType> certificateTypes) {
super(type);
this.isClientExtension = isClient;
this.certificateTypes = certificateTypes;
}
// Methods ////////////////////////////////////////////////////////
public boolean isClientExtension() {
return isClientExtension;
}
@Override
public int getLength() {
if (isClientExtension) {
// fixed: type (2 bytes), length (2 bytes), the list length field (1 byte)
// each certificate type in the list uses 1 byte
return 5 + certificateTypes.size();
} else {
// type (2 bytes), length (2 bytes), the certificate type (1 byte)
return 5;
}
}
public String toString() {
return super.toString();
}
// Serialization //////////////////////////////////////////////////
@Override
public byte[] toByteArray() {
DatagramWriter writer = new DatagramWriter();
writer.writeBytes(super.toByteArray());
if (isClientExtension) {
int listLength = certificateTypes.size();
writer.write(listLength + 1, LENGTH_BITS);
writer.write(listLength, LIST_FIELD_LENGTH_BITS);
for (CertificateType type : certificateTypes) {
writer.write(type.getCode(), EXTENSION_TYPE_BITS);
}
} else {
// we assume the list contains exactly one element
writer.write(1, LENGTH_BITS);
writer.write(certificateTypes.get(0).getCode(), EXTENSION_TYPE_BITS);
}
return writer.toByteArray();
}
// Enums //////////////////////////////////////////////////////////
/**
* See <a href=
* "http://tools.ietf.org/html/draft-ietf-tls-oob-pubkey-03#section-3.1"
* >3.1. ClientHello</a> for the definition. Note: The RawPublicKey code is
* <tt>TBD</tt>, but we assumed for now the reasonable value 2.
*
* @author Stefan Jucker
*
*/
public enum CertificateType {
// TODO this maybe change in the future
X_509(0), OPEN_PGP(1), RAW_PUBLIC_KEY(2);
private int code;
private CertificateType(int code) {
this.code = code;
}
public static CertificateType getTypeFromCode(int code) {
switch (code) {
case 0:
return X_509;
case 1:
return OPEN_PGP;
case 2:
return RAW_PUBLIC_KEY;
default:
return null;
}
}
int getCode() {
return code;
}
}
// Getters and Setters ////////////////////////////////////////////
public void addCertificateType(CertificateType certificateType) {
if (!isClientExtension && this.certificateTypes.size() > 0) {
// the server is only allowed to include 1 certificate type in its ServerHello
return;
}
this.certificateTypes.add(certificateType);
}
public List<CertificateType> getCertificateTypes() {
return certificateTypes;
}
}