/*******************************************************************************
* 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.DatagramReader;
import ch.ethz.inf.vs.scandium.util.DatagramWriter;
/**
* The supported point formats extension. See <a href="http://tools.ietf.org/html/rfc4492#section-5.1.2">RFC 4492,
* 5.1.2. Supported Point Formats Extension</a>.
*
* @author Stefan Jucker
*
*/
public class SupportedPointFormatsExtension extends HelloExtension {
// DTLS-specific constants ////////////////////////////////////////
private static final int LIST_LENGTH_BITS = 8;
private static final int POINT_FORMAT_BITS = 8;
// Members ////////////////////////////////////////////////////////
/**
* Items in here are ordered according to the client's preferences (favorite
* choice first).
*/
List<ECPointFormat> ecPointFormatList;
// Constructors ///////////////////////////////////////////////////
public SupportedPointFormatsExtension(List<ECPointFormat> ecPointFormatList) {
super(ExtensionType.EC_POINT_FORMATS);
this.ecPointFormatList = ecPointFormatList;
}
// Methods ////////////////////////////////////////////////////////
public void addECPointFormat(ECPointFormat format) {
ecPointFormatList.add(format);
}
@Override
public int getLength() {
// fixed: type (2 bytes), length (2 bytes), list length (1 byte)
// variable: number of point formats
return 5 + ecPointFormatList.size();
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder(super.toString());
sb.append("\t\t\t\tLength: " + (getLength() - 4) + "\n");
sb.append("\t\t\t\tEC point formats length: " + (getLength() - 5) + "\n");
sb.append("\t\t\t\tElliptic Curves Point Formats (" + ecPointFormatList.size() + "):\n");
for (ECPointFormat format : ecPointFormatList) {
sb.append("\t\t\t\t\tEC point format: " + format.toString() + "\n");
}
return sb.toString();
}
// Serialization //////////////////////////////////////////////////
@Override
public byte[] toByteArray() {
DatagramWriter writer = new DatagramWriter();
writer.writeBytes(super.toByteArray());
int listLength = ecPointFormatList.size();
// list length + list length field (1 byte)
writer.write(listLength + 1, LENGTH_BITS);
writer.write(listLength, LIST_LENGTH_BITS);
for (ECPointFormat format : ecPointFormatList) {
writer.write(format.getId(), POINT_FORMAT_BITS);
}
return writer.toByteArray();
}
public static HelloExtension fromByteArray(byte[] byteArray) {
DatagramReader reader = new DatagramReader(byteArray);
int listLength = reader.read(LIST_LENGTH_BITS);
List<ECPointFormat> ecPointFormatList = new ArrayList<ECPointFormat>();
while (listLength > 0) {
ECPointFormat format = ECPointFormat.getECPointFormatById(reader.read(POINT_FORMAT_BITS));
ecPointFormatList.add(format);
// one point format uses 1 byte
listLength -= 1;
}
return new SupportedPointFormatsExtension(ecPointFormatList);
}
// EC point format Enum ///////////////////////////////////////////
/**
* See <a href="http://tools.ietf.org/html/rfc4492#section-5.1.2">RFC 4492,
* 5.1.2. Supported Point Formats Extension</a>.
*
* @author Stefan Jucker
*
*/
public enum ECPointFormat {
UNCOMPRESSED(0), ANSIX962_COMPRESSED_PRIME(1), ANSIX962_COMPRESSED_CHAR2(2);
private int id;
private ECPointFormat(int id) {
this.id = id;
}
public int getId() {
return id;
}
@Override
public String toString() {
switch (id) {
case 0:
return "uncompressed (" + id + ")";
case 1:
return "ansiX962_compressed_prime (" + id + ")";
case 2:
return "ansiX962_compressed_char2 (" + id + ")";
default:
return "";
}
}
public static ECPointFormat getECPointFormatById(int id) {
switch (id) {
case 0:
return ECPointFormat.UNCOMPRESSED;
case 1:
return ECPointFormat.ANSIX962_COMPRESSED_PRIME;
case 2:
return ECPointFormat.ANSIX962_COMPRESSED_CHAR2;
default:
return null;
}
}
}
}