1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/mobile/android/thirdparty/com/googlecode/eyesfree/braille/selfbraille/SelfBrailleClient.java Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,267 @@
1.4 +/*
1.5 + * Copyright (C) 2012 Google Inc.
1.6 + *
1.7 + * Licensed under the Apache License, Version 2.0 (the "License"); you may not
1.8 + * use this file except in compliance with the License. You may obtain a copy of
1.9 + * the License at
1.10 + *
1.11 + * http://www.apache.org/licenses/LICENSE-2.0
1.12 + *
1.13 + * Unless required by applicable law or agreed to in writing, software
1.14 + * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
1.15 + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
1.16 + * License for the specific language governing permissions and limitations under
1.17 + * the License.
1.18 + */
1.19 +
1.20 +package com.googlecode.eyesfree.braille.selfbraille;
1.21 +
1.22 +import android.content.ComponentName;
1.23 +import android.content.Context;
1.24 +import android.content.Intent;
1.25 +import android.content.ServiceConnection;
1.26 +import android.content.pm.PackageInfo;
1.27 +import android.content.pm.PackageManager;
1.28 +import android.content.pm.Signature;
1.29 +import android.os.Binder;
1.30 +import android.os.Handler;
1.31 +import android.os.IBinder;
1.32 +import android.os.Message;
1.33 +import android.os.RemoteException;
1.34 +import android.util.Log;
1.35 +
1.36 +import java.security.MessageDigest;
1.37 +import java.security.NoSuchAlgorithmException;
1.38 +
1.39 +/**
1.40 + * Client-side interface to the self brailling interface.
1.41 + *
1.42 + * Threading: Instances of this object should be created and shut down
1.43 + * in a thread with a {@link Looper} associated with it. Other methods may
1.44 + * be called on any thread.
1.45 + */
1.46 +public class SelfBrailleClient {
1.47 + private static final String LOG_TAG =
1.48 + SelfBrailleClient.class.getSimpleName();
1.49 + private static final String ACTION_SELF_BRAILLE_SERVICE =
1.50 + "com.googlecode.eyesfree.braille.service.ACTION_SELF_BRAILLE_SERVICE";
1.51 + private static final String BRAILLE_BACK_PACKAGE =
1.52 + "com.googlecode.eyesfree.brailleback";
1.53 + private static final Intent mServiceIntent =
1.54 + new Intent(ACTION_SELF_BRAILLE_SERVICE)
1.55 + .setPackage(BRAILLE_BACK_PACKAGE);
1.56 + /**
1.57 + * SHA-1 hash value of the Eyes-Free release key certificate, used to sign
1.58 + * BrailleBack. It was generated from the keystore with:
1.59 + * $ keytool -exportcert -keystore <keystorefile> -alias android.keystore \
1.60 + * > cert
1.61 + * $ keytool -printcert -file cert
1.62 + */
1.63 + // The typecasts are to silence a compiler warning about loss of precision
1.64 + private static final byte[] EYES_FREE_CERT_SHA1 = new byte[] {
1.65 + (byte) 0x9B, (byte) 0x42, (byte) 0x4C, (byte) 0x2D,
1.66 + (byte) 0x27, (byte) 0xAD, (byte) 0x51, (byte) 0xA4,
1.67 + (byte) 0x2A, (byte) 0x33, (byte) 0x7E, (byte) 0x0B,
1.68 + (byte) 0xB6, (byte) 0x99, (byte) 0x1C, (byte) 0x76,
1.69 + (byte) 0xEC, (byte) 0xA4, (byte) 0x44, (byte) 0x61
1.70 + };
1.71 + /**
1.72 + * Delay before the first rebind attempt on bind error or service
1.73 + * disconnect.
1.74 + */
1.75 + private static final int REBIND_DELAY_MILLIS = 500;
1.76 + private static final int MAX_REBIND_ATTEMPTS = 5;
1.77 +
1.78 + private final Binder mIdentity = new Binder();
1.79 + private final Context mContext;
1.80 + private final boolean mAllowDebugService;
1.81 + private final SelfBrailleHandler mHandler = new SelfBrailleHandler();
1.82 + private boolean mShutdown = false;
1.83 +
1.84 + /**
1.85 + * Written in handler thread, read in any thread calling methods on the
1.86 + * object.
1.87 + */
1.88 + private volatile Connection mConnection;
1.89 + /** Protected by synchronizing on mHandler. */
1.90 + private int mNumFailedBinds = 0;
1.91 +
1.92 + /**
1.93 + * Constructs an instance of this class. {@code context} is used to bind
1.94 + * to the self braille service. The current thread must have a Looper
1.95 + * associated with it. If {@code allowDebugService} is true, this instance
1.96 + * will connect to a BrailleBack service without requiring it to be signed
1.97 + * by the release key used to sign BrailleBack.
1.98 + */
1.99 + public SelfBrailleClient(Context context, boolean allowDebugService) {
1.100 + mContext = context;
1.101 + mAllowDebugService = allowDebugService;
1.102 + doBindService();
1.103 + }
1.104 +
1.105 + /**
1.106 + * Shuts this instance down, deallocating any global resources it is using.
1.107 + * This method must be called on the same thread that created this object.
1.108 + */
1.109 + public void shutdown() {
1.110 + mShutdown = true;
1.111 + doUnbindService();
1.112 + }
1.113 +
1.114 + public void write(WriteData writeData) {
1.115 + writeData.validate();
1.116 + ISelfBrailleService localService = getSelfBrailleService();
1.117 + if (localService != null) {
1.118 + try {
1.119 + localService.write(mIdentity, writeData);
1.120 + } catch (RemoteException ex) {
1.121 + Log.e(LOG_TAG, "Self braille write failed", ex);
1.122 + }
1.123 + }
1.124 + }
1.125 +
1.126 + private void doBindService() {
1.127 + Connection localConnection = new Connection();
1.128 + if (!mContext.bindService(mServiceIntent, localConnection,
1.129 + Context.BIND_AUTO_CREATE)) {
1.130 + Log.e(LOG_TAG, "Failed to bind to service");
1.131 + mHandler.scheduleRebind();
1.132 + return;
1.133 + }
1.134 + mConnection = localConnection;
1.135 + Log.i(LOG_TAG, "Bound to self braille service");
1.136 + }
1.137 +
1.138 + private void doUnbindService() {
1.139 + if (mConnection != null) {
1.140 + ISelfBrailleService localService = getSelfBrailleService();
1.141 + if (localService != null) {
1.142 + try {
1.143 + localService.disconnect(mIdentity);
1.144 + } catch (RemoteException ex) {
1.145 + // Nothing to do.
1.146 + }
1.147 + }
1.148 + mContext.unbindService(mConnection);
1.149 + mConnection = null;
1.150 + }
1.151 + }
1.152 +
1.153 + private ISelfBrailleService getSelfBrailleService() {
1.154 + Connection localConnection = mConnection;
1.155 + if (localConnection != null) {
1.156 + return localConnection.mService;
1.157 + }
1.158 + return null;
1.159 + }
1.160 +
1.161 + private boolean verifyPackage() {
1.162 + PackageManager pm = mContext.getPackageManager();
1.163 + PackageInfo pi;
1.164 + try {
1.165 + pi = pm.getPackageInfo(BRAILLE_BACK_PACKAGE,
1.166 + PackageManager.GET_SIGNATURES);
1.167 + } catch (PackageManager.NameNotFoundException ex) {
1.168 + Log.w(LOG_TAG, "Can't verify package " + BRAILLE_BACK_PACKAGE,
1.169 + ex);
1.170 + return false;
1.171 + }
1.172 + MessageDigest digest;
1.173 + try {
1.174 + digest = MessageDigest.getInstance("SHA-1");
1.175 + } catch (NoSuchAlgorithmException ex) {
1.176 + Log.e(LOG_TAG, "SHA-1 not supported", ex);
1.177 + return false;
1.178 + }
1.179 + // Check if any of the certificates match our hash.
1.180 + for (Signature signature : pi.signatures) {
1.181 + digest.update(signature.toByteArray());
1.182 + if (MessageDigest.isEqual(EYES_FREE_CERT_SHA1, digest.digest())) {
1.183 + return true;
1.184 + }
1.185 + digest.reset();
1.186 + }
1.187 + if (mAllowDebugService) {
1.188 + Log.w(LOG_TAG, String.format(
1.189 + "*** %s connected to BrailleBack with invalid (debug?) "
1.190 + + "signature ***",
1.191 + mContext.getPackageName()));
1.192 + return true;
1.193 + }
1.194 + return false;
1.195 + }
1.196 + private class Connection implements ServiceConnection {
1.197 + // Read in application threads, written in main thread.
1.198 + private volatile ISelfBrailleService mService;
1.199 +
1.200 + @Override
1.201 + public void onServiceConnected(ComponentName className,
1.202 + IBinder binder) {
1.203 + if (!verifyPackage()) {
1.204 + Log.w(LOG_TAG, String.format("Service certificate mismatch "
1.205 + + "for %s, dropping connection",
1.206 + BRAILLE_BACK_PACKAGE));
1.207 + mHandler.unbindService();
1.208 + return;
1.209 + }
1.210 + Log.i(LOG_TAG, "Connected to self braille service");
1.211 + mService = ISelfBrailleService.Stub.asInterface(binder);
1.212 + synchronized (mHandler) {
1.213 + mNumFailedBinds = 0;
1.214 + }
1.215 + }
1.216 +
1.217 + @Override
1.218 + public void onServiceDisconnected(ComponentName className) {
1.219 + Log.e(LOG_TAG, "Disconnected from self braille service");
1.220 + mService = null;
1.221 + // Retry by rebinding.
1.222 + mHandler.scheduleRebind();
1.223 + }
1.224 + }
1.225 +
1.226 + private class SelfBrailleHandler extends Handler {
1.227 + private static final int MSG_REBIND_SERVICE = 1;
1.228 + private static final int MSG_UNBIND_SERVICE = 2;
1.229 +
1.230 + public void scheduleRebind() {
1.231 + synchronized (this) {
1.232 + if (mNumFailedBinds < MAX_REBIND_ATTEMPTS) {
1.233 + int delay = REBIND_DELAY_MILLIS << mNumFailedBinds;
1.234 + sendEmptyMessageDelayed(MSG_REBIND_SERVICE, delay);
1.235 + ++mNumFailedBinds;
1.236 + }
1.237 + }
1.238 + }
1.239 +
1.240 + public void unbindService() {
1.241 + sendEmptyMessage(MSG_UNBIND_SERVICE);
1.242 + }
1.243 +
1.244 + @Override
1.245 + public void handleMessage(Message msg) {
1.246 + switch (msg.what) {
1.247 + case MSG_REBIND_SERVICE:
1.248 + handleRebindService();
1.249 + break;
1.250 + case MSG_UNBIND_SERVICE:
1.251 + handleUnbindService();
1.252 + break;
1.253 + }
1.254 + }
1.255 +
1.256 + private void handleRebindService() {
1.257 + if (mShutdown) {
1.258 + return;
1.259 + }
1.260 + if (mConnection != null) {
1.261 + doUnbindService();
1.262 + }
1.263 + doBindService();
1.264 + }
1.265 +
1.266 + private void handleUnbindService() {
1.267 + doUnbindService();
1.268 + }
1.269 + }
1.270 +}
