/*
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* Copyright (C) 2008 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.server.location;
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import android.net.TrafficStats;
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import android.text.TextUtils;
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import android.util.Log;
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import com.android.internal.util.TrafficStatsConstants;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.net.HttpURLConnection;
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import java.net.URL;
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import java.util.Properties;
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import java.util.Random;
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import java.util.concurrent.TimeUnit;
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/**
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* A class for downloading GPS PSDS data.
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*
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* {@hide}
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*/
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public class GpsPsdsDownloader {
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private static final String TAG = "GpsPsdsDownloader";
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private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
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private static final long MAXIMUM_CONTENT_LENGTH_BYTES = 1000000; // 1MB.
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private static final String DEFAULT_USER_AGENT = "Android";
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private static final int CONNECTION_TIMEOUT_MS = (int) TimeUnit.SECONDS.toMillis(30);
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private static final int READ_TIMEOUT_MS = (int) TimeUnit.SECONDS.toMillis(60);
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private final String[] mPsdsServers;
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// to load balance our server requests
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private int mNextServerIndex;
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private final String mUserAgent;
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GpsPsdsDownloader(Properties properties) {
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// read PSDS servers from the Properties object
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int count = 0;
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String server1 = properties.getProperty("XTRA_SERVER_1");
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String server2 = properties.getProperty("XTRA_SERVER_2");
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String server3 = properties.getProperty("XTRA_SERVER_3");
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if (server1 != null) count++;
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if (server2 != null) count++;
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if (server3 != null) count++;
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// Set User Agent from properties, if possible.
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String agent = properties.getProperty("XTRA_USER_AGENT");
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if (TextUtils.isEmpty(agent)) {
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mUserAgent = DEFAULT_USER_AGENT;
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} else {
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mUserAgent = agent;
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}
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if (count == 0) {
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Log.e(TAG, "No PSDS servers were specified in the GPS configuration");
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mPsdsServers = null;
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} else {
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mPsdsServers = new String[count];
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count = 0;
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if (server1 != null) mPsdsServers[count++] = server1;
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if (server2 != null) mPsdsServers[count++] = server2;
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if (server3 != null) mPsdsServers[count++] = server3;
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// randomize first server
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Random random = new Random();
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mNextServerIndex = random.nextInt(count);
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}
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}
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byte[] downloadPsdsData() {
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byte[] result = null;
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int startIndex = mNextServerIndex;
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if (mPsdsServers == null) {
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return null;
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}
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// load balance our requests among the available servers
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while (result == null) {
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final int oldTag = TrafficStats.getAndSetThreadStatsTag(
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TrafficStatsConstants.TAG_SYSTEM_GPS);
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try {
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result = doDownload(mPsdsServers[mNextServerIndex]);
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} finally {
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TrafficStats.setThreadStatsTag(oldTag);
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}
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// increment mNextServerIndex and wrap around if necessary
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mNextServerIndex++;
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if (mNextServerIndex == mPsdsServers.length) {
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mNextServerIndex = 0;
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}
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// break if we have tried all the servers
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if (mNextServerIndex == startIndex) break;
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}
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return result;
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}
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protected byte[] doDownload(String url) {
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if (DEBUG) Log.d(TAG, "Downloading PSDS data from " + url);
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HttpURLConnection connection = null;
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try {
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connection = (HttpURLConnection) (new URL(url)).openConnection();
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connection.setRequestProperty(
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"Accept",
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"*/*, application/vnd.wap.mms-message, application/vnd.wap.sic");
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connection.setRequestProperty(
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"x-wap-profile",
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"http://www.openmobilealliance.org/tech/profiles/UAPROF/ccppschema-20021212#");
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connection.setConnectTimeout(CONNECTION_TIMEOUT_MS);
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connection.setReadTimeout(READ_TIMEOUT_MS);
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connection.connect();
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int statusCode = connection.getResponseCode();
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if (statusCode != HttpURLConnection.HTTP_OK) {
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if (DEBUG) Log.d(TAG, "HTTP error downloading gps PSDS: " + statusCode);
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return null;
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}
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try (InputStream in = connection.getInputStream()) {
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ByteArrayOutputStream bytes = new ByteArrayOutputStream();
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byte[] buffer = new byte[1024];
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int count;
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while ((count = in.read(buffer)) != -1) {
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bytes.write(buffer, 0, count);
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if (bytes.size() > MAXIMUM_CONTENT_LENGTH_BYTES) {
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if (DEBUG) Log.d(TAG, "PSDS file too large");
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return null;
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}
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}
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return bytes.toByteArray();
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}
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} catch (IOException ioe) {
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if (DEBUG) Log.d(TAG, "Error downloading gps PSDS: ", ioe);
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} finally {
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if (connection != null) {
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connection.disconnect();
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}
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}
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return null;
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}
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}
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