| /* |
| * Copyright (C) 2011 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 android.util; |
| |
| import android.content.ContentResolver; |
| import android.content.Context; |
| import android.content.res.Resources; |
| import android.net.ConnectivityManager; |
| import android.net.NetworkInfo; |
| import android.net.SntpClient; |
| import android.os.SystemClock; |
| import android.provider.Settings; |
| import android.text.TextUtils; |
| |
| /** |
| * {@link TrustedTime} that connects with a remote NTP server as its trusted |
| * time source. |
| * |
| * @hide |
| */ |
| public class NtpTrustedTime implements TrustedTime { |
| private static final String TAG = "NtpTrustedTime"; |
| private static final boolean LOGD = false; |
| |
| private static NtpTrustedTime sSingleton; |
| private static Context sContext; |
| |
| private final String mServer; |
| private final long mTimeout; |
| |
| private ConnectivityManager mCM; |
| |
| private boolean mHasCache; |
| private long mCachedNtpTime; |
| private long mCachedNtpElapsedRealtime; |
| private long mCachedNtpCertainty; |
| |
| private NtpTrustedTime(String server, long timeout) { |
| if (LOGD) Log.d(TAG, "creating NtpTrustedTime using " + server); |
| mServer = server; |
| mTimeout = timeout; |
| } |
| |
| public static synchronized NtpTrustedTime getInstance(Context context) { |
| if (sSingleton == null) { |
| final Resources res = context.getResources(); |
| final ContentResolver resolver = context.getContentResolver(); |
| |
| final String defaultServer = res.getString( |
| com.android.internal.R.string.config_ntpServer); |
| final long defaultTimeout = res.getInteger( |
| com.android.internal.R.integer.config_ntpTimeout); |
| |
| final String secureServer = Settings.Global.getString( |
| resolver, Settings.Global.NTP_SERVER); |
| final long timeout = Settings.Global.getLong( |
| resolver, Settings.Global.NTP_TIMEOUT, defaultTimeout); |
| |
| final String server = secureServer != null ? secureServer : defaultServer; |
| sSingleton = new NtpTrustedTime(server, timeout); |
| sContext = context; |
| } |
| |
| return sSingleton; |
| } |
| |
| @Override |
| public boolean forceRefresh() { |
| if (TextUtils.isEmpty(mServer)) { |
| // missing server, so no trusted time available |
| return false; |
| } |
| |
| // We can't do this at initialization time: ConnectivityService might not be running yet. |
| synchronized (this) { |
| if (mCM == null) { |
| mCM = (ConnectivityManager) sContext.getSystemService(Context.CONNECTIVITY_SERVICE); |
| } |
| } |
| |
| final NetworkInfo ni = mCM == null ? null : mCM.getActiveNetworkInfo(); |
| if (ni == null || !ni.isConnected()) { |
| if (LOGD) Log.d(TAG, "forceRefresh: no connectivity"); |
| return false; |
| } |
| |
| |
| if (LOGD) Log.d(TAG, "forceRefresh() from cache miss"); |
| final SntpClient client = new SntpClient(); |
| if (client.requestTime(mServer, (int) mTimeout)) { |
| mHasCache = true; |
| mCachedNtpTime = client.getNtpTime(); |
| mCachedNtpElapsedRealtime = client.getNtpTimeReference(); |
| mCachedNtpCertainty = client.getRoundTripTime() / 2; |
| return true; |
| } else { |
| return false; |
| } |
| } |
| |
| @Override |
| public boolean hasCache() { |
| return mHasCache; |
| } |
| |
| @Override |
| public long getCacheAge() { |
| if (mHasCache) { |
| return SystemClock.elapsedRealtime() - mCachedNtpElapsedRealtime; |
| } else { |
| return Long.MAX_VALUE; |
| } |
| } |
| |
| @Override |
| public long getCacheCertainty() { |
| if (mHasCache) { |
| return mCachedNtpCertainty; |
| } else { |
| return Long.MAX_VALUE; |
| } |
| } |
| |
| @Override |
| public long currentTimeMillis() { |
| if (!mHasCache) { |
| throw new IllegalStateException("Missing authoritative time source"); |
| } |
| if (LOGD) Log.d(TAG, "currentTimeMillis() cache hit"); |
| |
| // current time is age after the last ntp cache; callers who |
| // want fresh values will hit makeAuthoritative() first. |
| return mCachedNtpTime + getCacheAge(); |
| } |
| |
| public long getCachedNtpTime() { |
| if (LOGD) Log.d(TAG, "getCachedNtpTime() cache hit"); |
| return mCachedNtpTime; |
| } |
| |
| public long getCachedNtpTimeReference() { |
| return mCachedNtpElapsedRealtime; |
| } |
| } |