| /* |
| * Copyright (C) 2017 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.server.net.watchlist; |
| |
| import com.android.internal.util.HexDump; |
| |
| import java.io.FileDescriptor; |
| import java.io.PrintWriter; |
| import java.util.Collections; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Set; |
| |
| /** |
| * Helper class to store a set of harmful CRC32s in memory. |
| * TODO: Optimize memory usage using int array with binary search. |
| */ |
| class HarmfulCrcs { |
| |
| private final Set<Integer> mCrcSet; |
| |
| HarmfulCrcs(List<byte[]> digests) { |
| final HashSet<Integer> crcSet = new HashSet<>(); |
| final int size = digests.size(); |
| for (int i = 0; i < size; i++) { |
| byte[] bytes = digests.get(i); |
| if (bytes.length <= 4) { |
| int crc = 0; |
| for (byte b : bytes) { |
| // Remember byte is signed |
| crc = (crc << 8) | (b & 0xff); |
| } |
| crcSet.add(crc); |
| } |
| } |
| mCrcSet = Collections.unmodifiableSet(crcSet); |
| } |
| |
| public boolean contains(int crc) { |
| return mCrcSet.contains(crc); |
| } |
| |
| public void dump(FileDescriptor fd, PrintWriter pw, String[] args) { |
| for (int crc : mCrcSet) { |
| pw.println(HexDump.toHexString(crc)); |
| } |
| pw.println(""); |
| } |
| } |