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/*
* Copyright (C) 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.internal.net.ipsec.ike.message;
import android.annotation.Nullable;
import android.net.ipsec.ike.exceptions.IkeProtocolException;
import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.net.ipsec.ike.crypto.IkeCipher;
import com.android.internal.net.ipsec.ike.crypto.IkeMacIntegrity;
import com.android.internal.net.ipsec.ike.exceptions.InvalidSyntaxException;
import java.nio.ByteBuffer;
import java.security.GeneralSecurityException;
/**
* IkeSkfPayload represents an Encrypted and Authenticated Fragment Payload.
*
* @see <a href="https://tools.ietf.org/html/rfc7383">RFC 7383, Internet Key Exchange Protocol
* Version 2 (IKEv2) Message Fragmentation</a>
*/
public final class IkeSkfPayload extends IkeSkPayload {
public static final int SKF_HEADER_LEN = 4;
/** Current Fragment message number, starting from 1 */
public final int fragmentNum;
/** Number of Fragment messages into which the original message was divided */
public final int totalFragments;
/**
* Construct an instance of IkeSkfPayload by authenticating and decrypting an incoming packet.
*
* <p>SKF Payload with invalid fragmentNum or invalid totalFragments, or cannot be authenticated
* or decrypted MUST be discarded
*
* @param critical indicates if it is a critical payload.
* @param message the byte array contains the whole IKE message.
* @param integrityMac the negotiated integrity algorithm.
* @param decryptCipher the negotiated encryption algorithm.
* @param integrityKey the negotiated integrity algorithm key.
* @param decryptionKey the negotiated decryption key.
*/
IkeSkfPayload(
boolean critical,
byte[] message,
@Nullable IkeMacIntegrity integrityMac,
IkeCipher decryptCipher,
byte[] integrityKey,
byte[] decryptionKey)
throws IkeProtocolException, GeneralSecurityException {
super(
true /*isSkf*/,
critical,
IkeHeader.IKE_HEADER_LENGTH + GENERIC_HEADER_LENGTH + SKF_HEADER_LEN,
message,
integrityMac,
decryptCipher,
integrityKey,
decryptionKey);
// TODO: Support constructing IkeEncryptedPayloadBody using AEAD.
ByteBuffer inputBuffer = ByteBuffer.wrap(message);
inputBuffer.get(new byte[IkeHeader.IKE_HEADER_LENGTH + GENERIC_HEADER_LENGTH]);
fragmentNum = Short.toUnsignedInt(inputBuffer.getShort());
totalFragments = Short.toUnsignedInt(inputBuffer.getShort());
if (fragmentNum < 1 || totalFragments < 1 || fragmentNum > totalFragments) {
throw new InvalidSyntaxException(
"Received invalid Fragment Number or Total Fragments Number. Fragment Number: "
+ fragmentNum
+ " Total Fragments: "
+ totalFragments);
}
}
/**
* Construct an instance of IkeSkfPayload for building outbound packet.
*
* @param ikeHeader the IKE header.
* @param firstPayloadType the type of first payload nested in SkPayload.
* @param unencryptedPayloads the encoded payload list to protect.
* @param integrityMac the negotiated integrity algorithm.
* @param encryptCipher the negotiated encryption algorithm.
* @param integrityKey the negotiated integrity algorithm key.
* @param encryptionKey the negotiated encryption key.
*/
IkeSkfPayload(
IkeHeader ikeHeader,
@PayloadType int firstPayloadType,
byte[] unencryptedPayloads,
@Nullable IkeMacIntegrity integrityMac,
IkeCipher encryptCipher,
byte[] integrityKey,
byte[] encryptionKey,
int fragNum,
int totalFrags) {
super(
ikeHeader,
firstPayloadType,
encodeSkfHeader(fragNum, totalFrags),
unencryptedPayloads,
integrityMac,
encryptCipher,
integrityKey,
encryptionKey);
fragmentNum = fragNum;
totalFragments = totalFrags;
}
/** Construct an instance of IkeSkfPayload for testing. */
@VisibleForTesting
IkeSkfPayload(IkeEncryptedPayloadBody encryptedPayloadBody, int fragNum, int totalFrags) {
super(true /*isSkf*/, encryptedPayloadBody);
fragmentNum = fragNum;
totalFragments = totalFrags;
}
@VisibleForTesting
static byte[] encodeSkfHeader(int fragNum, int totalFrags) {
ByteBuffer buffer = ByteBuffer.allocate(SKF_HEADER_LEN);
buffer.putShort((short) fragNum).putShort((short) totalFrags);
return buffer.array();
}
/**
* Encode this payload to a ByteBuffer.
*
* @param nextPayload type of payload that follows this payload.
* @param byteBuffer destination ByteBuffer that stores encoded payload.
*/
@Override
protected void encodeToByteBuffer(@PayloadType int nextPayload, ByteBuffer byteBuffer) {
encodePayloadHeaderToByteBuffer(nextPayload, getPayloadLength(), byteBuffer);
byteBuffer
.putShort((short) fragmentNum)
.putShort((short) totalFragments)
.put(mIkeEncryptedPayloadBody.encode());
}
/**
* Get entire payload length.
*
* @return entire payload length.
*/
@Override
protected int getPayloadLength() {
return GENERIC_HEADER_LENGTH + SKF_HEADER_LEN + mIkeEncryptedPayloadBody.getLength();
}
/**
* Return the payload type as a String.
*
* @return the payload type as a String.
*/
@Override
public String getTypeString() {
return "SKF";
}
}
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