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/*
* 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.devicepolicy;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.util.AtomicFile;
import android.util.Slog;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.List;
/**
* Manages the blacklisted passwords.
*
* This caller must ensure synchronized access.
*/
public class PasswordBlacklist {
private static final String TAG = "PasswordBlacklist";
private final AtomicFile mFile;
/**
* Create an object to manage the password blacklist.
*
* This is a lightweight operation to prepare variables but not perform any IO.
*/
public PasswordBlacklist(File file) {
mFile = new AtomicFile(file);
}
/**
* Atomically replace the blacklist.
*
* Pass {@code null} for an empty list.
*/
public boolean savePasswordBlacklist(@NonNull String name, @NonNull List<String> blacklist) {
FileOutputStream fos = null;
try {
fos = mFile.startWrite();
final DataOutputStream out = buildStreamForWriting(fos);
final Header header = new Header(Header.VERSION_1, name, blacklist.size());
header.write(out);
final int blacklistSize = blacklist.size();
for (int i = 0; i < blacklistSize; ++i) {
out.writeUTF(blacklist.get(i));
}
out.flush();
mFile.finishWrite(fos);
return true;
} catch (IOException e) {
mFile.failWrite(fos);
return false;
}
}
/** @return the name of the blacklist or {@code null} if none set. */
public String getName() {
try (DataInputStream in = openForReading()) {
return Header.read(in).mName;
} catch (IOException e) {
Slog.wtf(TAG, "Failed to read blacklist file", e);
}
return null;
}
/** @return the number of blacklisted passwords. */
public int getSize() {
final int blacklistSize;
try (DataInputStream in = openForReading()) {
return Header.read(in).mSize;
} catch (IOException e) {
Slog.wtf(TAG, "Failed to read blacklist file", e);
}
return 0;
}
/** @return whether the password matches an blacklisted item. */
public boolean isPasswordBlacklisted(@NonNull String password) {
final int blacklistSize;
try (DataInputStream in = openForReading()) {
final Header header = Header.read(in);
for (int i = 0; i < header.mSize; ++i) {
if (in.readUTF().equals(password)) {
return true;
}
}
} catch (IOException e) {
Slog.wtf(TAG, "Failed to read blacklist file", e);
// Fail safe and block all passwords. Setting a new blacklist should resolve this
// problem which can be identified by examining the log.
return true;
}
return false;
}
/** Delete the blacklist completely from disk. */
public void delete() {
mFile.delete();
}
/** Get the file the blacklist is stored in. */
public File getFile() {
return mFile.getBaseFile();
}
private DataOutputStream buildStreamForWriting(FileOutputStream fos) {
return new DataOutputStream(new BufferedOutputStream(fos));
}
private DataInputStream openForReading() throws IOException {
return new DataInputStream(new BufferedInputStream(mFile.openRead()));
}
/**
* Helper to read and write the header of the blacklist file.
*/
private static class Header {
static final int VERSION_1 = 1;
final int mVersion; // File format version
final String mName;
final int mSize;
Header(int version, String name, int size) {
mVersion = version;
mName = name;
mSize = size;
}
void write(DataOutputStream out) throws IOException {
out.writeInt(mVersion);
out.writeUTF(mName);
out.writeInt(mSize);
}
static Header read(DataInputStream in) throws IOException {
final int version = in.readInt();
final String name = in.readUTF();
final int size = in.readInt();
return new Header(version, name, size);
}
}
}
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