1 /* 2 * Copyright (C) 2020 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.server.location.gnss; 18 19 import android.annotation.Nullable; 20 import android.net.TrafficStats; 21 import android.util.Log; 22 23 import com.android.internal.util.TrafficStatsConstants; 24 25 import java.io.ByteArrayOutputStream; 26 import java.io.IOException; 27 import java.io.InputStream; 28 import java.net.HttpURLConnection; 29 import java.net.URL; 30 import java.util.Properties; 31 import java.util.Random; 32 import java.util.concurrent.TimeUnit; 33 34 /** 35 * A class for downloading GNSS PSDS data. 36 * 37 * {@hide} 38 */ 39 class GnssPsdsDownloader { 40 41 private static final String TAG = "GnssPsdsDownloader"; 42 private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG); 43 private static final long MAXIMUM_CONTENT_LENGTH_BYTES = 1000000; // 1MB. 44 private static final int CONNECTION_TIMEOUT_MS = (int) TimeUnit.SECONDS.toMillis(30); 45 private static final int READ_TIMEOUT_MS = (int) TimeUnit.SECONDS.toMillis(60); 46 47 static final int LONG_TERM_PSDS_SERVER_INDEX = 1; 48 private static final int NORMAL_PSDS_SERVER_INDEX = 2; 49 private static final int REALTIME_PSDS_SERVER_INDEX = 3; 50 private static final int MAX_PSDS_TYPE_INDEX = 3; 51 52 private final String[] mLongTermPsdsServers; 53 private final String[] mPsdsServers; 54 // to load balance our server requests 55 private int mNextServerIndex; 56 GnssPsdsDownloader(Properties properties)57 GnssPsdsDownloader(Properties properties) { 58 // read PSDS servers from the Properties object 59 int count = 0; 60 String longTermPsdsServer1 = properties.getProperty("LONGTERM_PSDS_SERVER_1"); 61 String longTermPsdsServer2 = properties.getProperty("LONGTERM_PSDS_SERVER_2"); 62 String longTermPsdsServer3 = properties.getProperty("LONGTERM_PSDS_SERVER_3"); 63 if (longTermPsdsServer1 != null) count++; 64 if (longTermPsdsServer2 != null) count++; 65 if (longTermPsdsServer3 != null) count++; 66 67 if (count == 0) { 68 Log.e(TAG, "No Long-Term PSDS servers were specified in the GnssConfiguration"); 69 mLongTermPsdsServers = null; 70 } else { 71 mLongTermPsdsServers = new String[count]; 72 count = 0; 73 if (longTermPsdsServer1 != null) mLongTermPsdsServers[count++] = longTermPsdsServer1; 74 if (longTermPsdsServer2 != null) mLongTermPsdsServers[count++] = longTermPsdsServer2; 75 if (longTermPsdsServer3 != null) mLongTermPsdsServers[count++] = longTermPsdsServer3; 76 77 // randomize first server 78 Random random = new Random(); 79 mNextServerIndex = random.nextInt(count); 80 } 81 82 String normalPsdsServer = properties.getProperty("NORMAL_PSDS_SERVER"); 83 String realtimePsdsServer = properties.getProperty("REALTIME_PSDS_SERVER"); 84 mPsdsServers = new String[MAX_PSDS_TYPE_INDEX + 1]; 85 mPsdsServers[NORMAL_PSDS_SERVER_INDEX] = normalPsdsServer; 86 mPsdsServers[REALTIME_PSDS_SERVER_INDEX] = realtimePsdsServer; 87 } 88 89 @Nullable downloadPsdsData(int psdsType)90 byte[] downloadPsdsData(int psdsType) { 91 byte[] result = null; 92 int startIndex = mNextServerIndex; 93 94 if (psdsType == LONG_TERM_PSDS_SERVER_INDEX && mLongTermPsdsServers == null) { 95 return null; 96 } else if (psdsType > LONG_TERM_PSDS_SERVER_INDEX && psdsType <= MAX_PSDS_TYPE_INDEX 97 && mPsdsServers[psdsType] == null) { 98 return null; 99 } 100 101 if (psdsType == LONG_TERM_PSDS_SERVER_INDEX) { 102 // load balance our requests among the available servers 103 while (result == null) { 104 result = doDownloadWithTrafficAccounted(mLongTermPsdsServers[mNextServerIndex]); 105 106 // increment mNextServerIndex and wrap around if necessary 107 mNextServerIndex++; 108 if (mNextServerIndex == mLongTermPsdsServers.length) { 109 mNextServerIndex = 0; 110 } 111 // break if we have tried all the servers 112 if (mNextServerIndex == startIndex) break; 113 } 114 } else if (psdsType > LONG_TERM_PSDS_SERVER_INDEX && psdsType <= MAX_PSDS_TYPE_INDEX) { 115 result = doDownloadWithTrafficAccounted(mPsdsServers[psdsType]); 116 } 117 118 return result; 119 } 120 121 @Nullable doDownloadWithTrafficAccounted(String url)122 private byte[] doDownloadWithTrafficAccounted(String url) { 123 byte[] result; 124 final int oldTag = TrafficStats.getAndSetThreadStatsTag( 125 TrafficStatsConstants.TAG_SYSTEM_GPS); 126 try { 127 result = doDownload(url); 128 } finally { 129 TrafficStats.setThreadStatsTag(oldTag); 130 } 131 return result; 132 } 133 134 @Nullable doDownload(String url)135 private byte[] doDownload(String url) { 136 if (DEBUG) Log.d(TAG, "Downloading PSDS data from " + url); 137 138 HttpURLConnection connection = null; 139 try { 140 connection = (HttpURLConnection) (new URL(url)).openConnection(); 141 connection.setRequestProperty( 142 "Accept", 143 "*/*, application/vnd.wap.mms-message, application/vnd.wap.sic"); 144 connection.setRequestProperty( 145 "x-wap-profile", 146 "http://www.openmobilealliance.org/tech/profiles/UAPROF/ccppschema-20021212#"); 147 connection.setConnectTimeout(CONNECTION_TIMEOUT_MS); 148 connection.setReadTimeout(READ_TIMEOUT_MS); 149 150 connection.connect(); 151 int statusCode = connection.getResponseCode(); 152 if (statusCode != HttpURLConnection.HTTP_OK) { 153 if (DEBUG) Log.d(TAG, "HTTP error downloading gnss PSDS: " + statusCode); 154 return null; 155 } 156 157 try (InputStream in = connection.getInputStream()) { 158 ByteArrayOutputStream bytes = new ByteArrayOutputStream(); 159 byte[] buffer = new byte[1024]; 160 int count; 161 while ((count = in.read(buffer)) != -1) { 162 bytes.write(buffer, 0, count); 163 if (bytes.size() > MAXIMUM_CONTENT_LENGTH_BYTES) { 164 if (DEBUG) Log.d(TAG, "PSDS file too large"); 165 return null; 166 } 167 } 168 return bytes.toByteArray(); 169 } 170 } catch (IOException ioe) { 171 if (DEBUG) Log.d(TAG, "Error downloading gnss PSDS: ", ioe); 172 } finally { 173 if (connection != null) { 174 connection.disconnect(); 175 } 176 } 177 return null; 178 } 179 } 180