1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
|
/*
* 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.annotation.UnsupportedAppUsage;
import android.content.ContentResolver;
import android.content.Context;
import android.content.res.Resources;
import android.net.ConnectivityManager;
import android.net.Network;
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;
}
@UnsupportedAppUsage
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
@UnsupportedAppUsage
public boolean forceRefresh() {
// We can't do this at initialization time: ConnectivityService might not be running yet.
synchronized (this) {
if (mCM == null) {
mCM = sContext.getSystemService(ConnectivityManager.class);
}
}
final Network network = mCM == null ? null : mCM.getActiveNetwork();
return forceRefresh(network);
}
public boolean forceRefresh(Network network) {
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 = sContext.getSystemService(ConnectivityManager.class);
}
}
final NetworkInfo ni = mCM == null ? null : mCM.getNetworkInfo(network);
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, network)) {
mHasCache = true;
mCachedNtpTime = client.getNtpTime();
mCachedNtpElapsedRealtime = client.getNtpTimeReference();
mCachedNtpCertainty = client.getRoundTripTime() / 2;
return true;
} else {
return false;
}
}
@Override
@UnsupportedAppUsage
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
@UnsupportedAppUsage
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();
}
@UnsupportedAppUsage
public long getCachedNtpTime() {
if (LOGD) Log.d(TAG, "getCachedNtpTime() cache hit");
return mCachedNtpTime;
}
@UnsupportedAppUsage
public long getCachedNtpTimeReference() {
return mCachedNtpElapsedRealtime;
}
}
|
