1 /* 2 * Copyright (C) 2020 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.internal.net.eap.message.ttls; 18 19 import static com.android.internal.net.eap.EapAuthenticator.LOG; 20 21 import android.annotation.IntDef; 22 23 import com.android.internal.annotations.VisibleForTesting; 24 25 import java.lang.annotation.Retention; 26 import java.lang.annotation.RetentionPolicy; 27 import java.nio.ByteBuffer; 28 29 /** The inbound fragmentation helper is responsible for assembling fragmented EAP-TTLS data. */ 30 public class EapTtlsInboundFragmentationHelper { 31 private static final String TAG = EapTtlsInboundFragmentationHelper.class.getSimpleName(); 32 33 @Retention(RetentionPolicy.SOURCE) 34 @IntDef({ 35 FRAGMENTATION_STATUS_ACK, 36 FRAGMENTATION_STATUS_ASSEMBLED, 37 FRAGMENTATION_STATUS_INVALID 38 }) 39 public @interface FragmentationStatus {} 40 41 // ACK indicates that an inbound fragment has been processed and an ACK should be sent 42 public static final int FRAGMENTATION_STATUS_ACK = 0; 43 // ASSEMBLED indicates that fragments have been reasembeled and data can now be processed 44 public static final int FRAGMENTATION_STATUS_ASSEMBLED = 1; 45 // INVALID indicates some kind of failure likely due to an unexpected request or invalid data 46 public static final int FRAGMENTATION_STATUS_INVALID = 2; 47 48 @VisibleForTesting public boolean mIsAwaitingFragments = false; 49 @VisibleForTesting public ByteBuffer mFragmentedData; 50 51 /** 52 * This method is responsible for processing incoming fragmented data (RFC5281#9.2.2) 53 * 54 * @param typeData the type data to process 55 * @return a fragmentation status indicating the result of the process 56 */ assembleInboundMessage(EapTtlsTypeData typeData)57 public @FragmentationStatus int assembleInboundMessage(EapTtlsTypeData typeData) { 58 if (!mIsAwaitingFragments) { 59 if (typeData.isDataFragmented) { 60 mIsAwaitingFragments = true; 61 mFragmentedData = ByteBuffer.allocate(typeData.messageLength); 62 } else { 63 // If there is no fragmentation, simply return the full data in a byte array 64 mFragmentedData = ByteBuffer.wrap(typeData.data); 65 return FRAGMENTATION_STATUS_ASSEMBLED; 66 } 67 } else if (typeData.isLengthIncluded) { 68 // the length bit MUST only be set on the first packet for a fragmented packet 69 // (RFC5281#9.2.2) 70 LOG.e( 71 TAG, 72 "Fragmentation failure: Received a second or greater fragmented request" 73 + " with the length bit set."); 74 return FRAGMENTATION_STATUS_INVALID; 75 } 76 77 if (typeData.data.length > mFragmentedData.remaining()) { 78 LOG.e( 79 TAG, 80 "Fragmentation failure: Received more data then declared and failed to" 81 + " reassemble fragment."); 82 return FRAGMENTATION_STATUS_INVALID; 83 } 84 85 mFragmentedData.put(typeData.data); 86 87 if (typeData.isDataFragmented) { 88 return FRAGMENTATION_STATUS_ACK; 89 } 90 91 LOG.d(TAG, "Successfully assembled a fragment."); 92 mIsAwaitingFragments = false; 93 return FRAGMENTATION_STATUS_ASSEMBLED; 94 } 95 96 /** 97 * Retrieves assembled inbound fragmented data 98 * 99 * @return a byte array containing an assembled inbound fragment 100 */ getAssembledInboundFragment()101 public byte[] getAssembledInboundFragment() { 102 return mFragmentedData.array(); 103 } 104 105 /** 106 * Indicates whether a fragmentation session is currently in progress 107 * 108 * @return true if fragmentation is in progress 109 */ isAwaitingFragments()110 public boolean isAwaitingFragments() { 111 return mIsAwaitingFragments; 112 } 113 } 114