| /* |
| * Copyright (C) 2020 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.eap.message.ttls; |
| |
| import static com.android.internal.net.eap.EapAuthenticator.LOG; |
| |
| import android.annotation.IntDef; |
| |
| import com.android.internal.annotations.VisibleForTesting; |
| |
| import java.lang.annotation.Retention; |
| import java.lang.annotation.RetentionPolicy; |
| import java.nio.ByteBuffer; |
| |
| /** The inbound fragmentation helper is responsible for assembling fragmented EAP-TTLS data. */ |
| public class EapTtlsInboundFragmentationHelper { |
| private static final String TAG = EapTtlsInboundFragmentationHelper.class.getSimpleName(); |
| |
| @Retention(RetentionPolicy.SOURCE) |
| @IntDef({ |
| FRAGMENTATION_STATUS_ACK, |
| FRAGMENTATION_STATUS_ASSEMBLED, |
| FRAGMENTATION_STATUS_INVALID |
| }) |
| public @interface FragmentationStatus {} |
| |
| // ACK indicates that an inbound fragment has been processed and an ACK should be sent |
| public static final int FRAGMENTATION_STATUS_ACK = 0; |
| // ASSEMBLED indicates that fragments have been reasembeled and data can now be processed |
| public static final int FRAGMENTATION_STATUS_ASSEMBLED = 1; |
| // INVALID indicates some kind of failure likely due to an unexpected request or invalid data |
| public static final int FRAGMENTATION_STATUS_INVALID = 2; |
| |
| @VisibleForTesting public boolean mIsAwaitingFragments = false; |
| @VisibleForTesting public ByteBuffer mFragmentedData; |
| |
| /** |
| * This method is responsible for processing incoming fragmented data (RFC5281#9.2.2) |
| * |
| * @param typeData the type data to process |
| * @return a fragmentation status indicating the result of the process |
| */ |
| public @FragmentationStatus int assembleInboundMessage(EapTtlsTypeData typeData) { |
| if (!mIsAwaitingFragments) { |
| if (typeData.isDataFragmented) { |
| mIsAwaitingFragments = true; |
| mFragmentedData = ByteBuffer.allocate(typeData.messageLength); |
| } else { |
| // If there is no fragmentation, simply return the full data in a byte array |
| mFragmentedData = ByteBuffer.wrap(typeData.data); |
| return FRAGMENTATION_STATUS_ASSEMBLED; |
| } |
| } else if (typeData.isLengthIncluded) { |
| // the length bit MUST only be set on the first packet for a fragmented packet |
| // (RFC5281#9.2.2) |
| LOG.e( |
| TAG, |
| "Fragmentation failure: Received a second or greater fragmented request" |
| + " with the length bit set."); |
| return FRAGMENTATION_STATUS_INVALID; |
| } |
| |
| if (typeData.data.length > mFragmentedData.remaining()) { |
| LOG.e( |
| TAG, |
| "Fragmentation failure: Received more data then declared and failed to" |
| + " reassemble fragment."); |
| return FRAGMENTATION_STATUS_INVALID; |
| } |
| |
| mFragmentedData.put(typeData.data); |
| |
| if (typeData.isDataFragmented) { |
| return FRAGMENTATION_STATUS_ACK; |
| } |
| |
| LOG.d(TAG, "Successfully assembled a fragment."); |
| mIsAwaitingFragments = false; |
| return FRAGMENTATION_STATUS_ASSEMBLED; |
| } |
| |
| /** |
| * Retrieves assembled inbound fragmented data |
| * |
| * @return a byte array containing an assembled inbound fragment |
| */ |
| public byte[] getAssembledInboundFragment() { |
| return mFragmentedData.array(); |
| } |
| |
| /** |
| * Indicates whether a fragmentation session is currently in progress |
| * |
| * @return true if fragmentation is in progress |
| */ |
| public boolean isAwaitingFragments() { |
| return mIsAwaitingFragments; |
| } |
| } |