1 files changed, 96 insertions, 0 deletions
diff --git a/core/java/android/util/NtpTrustedTime.java b/core/java/android/util/NtpTrustedTime.java
new file mode 100644
index 000000000000..729c5064204e
--- /dev/null
+++ b/core/java/android/util/NtpTrustedTime.java
@@ -0,0 +1,96 @@
+/*
+ * 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.net.SntpClient;
+import android.os.SystemClock;
+
+/**
+ * {@link TrustedTime} that connects with a remote NTP server as its remote
+ * trusted time source.
+ *
+ * @hide
+ */
+public class NtpTrustedTime implements TrustedTime {
+    private String mNtpServer;
+    private long mNtpTimeout;
+
+    private boolean mHasCache;
+    private long mCachedNtpTime;
+    private long mCachedNtpElapsedRealtime;
+    private long mCachedNtpCertainty;
+
+    public NtpTrustedTime() {
+    }
+
+    public void setNtpServer(String server, long timeout) {
+        mNtpServer = server;
+        mNtpTimeout = timeout;
+    }
+
+    /** {@inheritDoc} */
+    public boolean forceRefresh() {
+        if (mNtpServer == null) {
+            throw new IllegalStateException("Missing NTP server");
+        }
+
+        final SntpClient client = new SntpClient();
+        if (client.requestTime(mNtpServer, (int) mNtpTimeout)) {
+            mHasCache = true;
+            mCachedNtpTime = client.getNtpTime();
+            mCachedNtpElapsedRealtime = client.getNtpTimeReference();
+            mCachedNtpCertainty = client.getRoundTripTime() / 2;
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    /** {@inheritDoc} */
+    public boolean hasCache() {
+        return mHasCache;
+    }
+
+    /** {@inheritDoc} */
+    public long getCacheAge() {
+        if (mHasCache) {
+            return SystemClock.elapsedRealtime() - mCachedNtpElapsedRealtime;
+        } else {
+            return Long.MAX_VALUE;
+        }
+    }
+
+    /** {@inheritDoc} */
+    public long getCacheCertainty() {
+        if (mHasCache) {
+            return mCachedNtpCertainty;
+        } else {
+            return Long.MAX_VALUE;
+        }
+    }
+
+    /** {@inheritDoc} */
+    public long currentTimeMillis() {
+        if (!mHasCache) {
+            throw new IllegalStateException("Missing authoritative time source");
+        }
+
+        // current time is age after the last ntp cache; callers who
+        // want fresh values will hit makeAuthoritative() first.
+        return mCachedNtpTime + getCacheAge();
+    }
+}