1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/mobile/android/base/background/datareporting/TelemetryRecorder.java Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,316 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.6 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +package org.mozilla.gecko.background.datareporting;
1.9 +
1.10 +import java.io.BufferedOutputStream;
1.11 +import java.io.File;
1.12 +import java.io.FileOutputStream;
1.13 +import java.io.IOException;
1.14 +import java.io.OutputStream;
1.15 +import java.io.UnsupportedEncodingException;
1.16 +import java.security.MessageDigest;
1.17 +import java.security.NoSuchAlgorithmException;
1.18 +
1.19 +import org.json.JSONObject;
1.20 +import org.mozilla.gecko.background.common.log.Logger;
1.21 +
1.22 +import android.util.Base64;
1.23 +
1.24 +/**
1.25 + * Writes telemetry ping to file.
1.26 + *
1.27 + * Also creates and updates a SHA-256 checksum for the payload to be included in the ping
1.28 + * file.
1.29 + *
1.30 + * A saved telemetry ping file consists of JSON in the following format,
1.31 + * {
1.32 + * "slug": "<uuid-string>",
1.33 + * "payload": "<escaped-json-data-string>",
1.34 + * "checksum": "<base64-sha-256-string>"
1.35 + * }
1.36 + *
1.37 + * This class writes first to a temporary file and then, after finishing the contents of the ping,
1.38 + * moves that to the file specified by the caller. This is to avoid uploads of partially written
1.39 + * ping files.
1.40 + *
1.41 + * The API provided by this class:
1.42 + * startPingFile() - opens stream to a tmp File in the Android cache directory and writes the slug header
1.43 + * appendPayload(String payloadContent) - appends to the payload of the ping and updates the checksum
1.44 + * finishPingFile() - writes the checksum to the tmp file and moves it to the File specified by the caller.
1.45 + *
1.46 + * In the case of errors, we try to close the stream and File.
1.47 + */
1.48 +public class TelemetryRecorder {
1.49 + private final String LOG_TAG = "TelemetryRecorder";
1.50 +
1.51 + private final File parentDir;
1.52 + private final String filename;
1.53 +
1.54 + private File tmpFile;
1.55 + private File destFile;
1.56 + private File cacheDir;
1.57 +
1.58 + private OutputStream outputStream;
1.59 + private MessageDigest checksum;
1.60 + private String base64Checksum;
1.61 +
1.62 + /**
1.63 + * Charset to use for writing pings; default is us-ascii.
1.64 + *
1.65 + * When telemetry calculates the checksum for the ping file, it lossily
1.66 + * converts utf-16 to ascii. Therefore we have to treat characters in the
1.67 + * traces as ascii rather than say utf-8. Otherwise we will get a "wrong"
1.68 + * checksum.
1.69 + */
1.70 + private String charset = "us-ascii";
1.71 +
1.72 + /**
1.73 + * Override blockSize in constructor if desired.
1.74 + * Default block size is that of BufferedOutputStream.
1.75 + */
1.76 + private int blockSize = 0;
1.77 +
1.78 + /**
1.79 + * Constructs a TelemetryRecorder for writing a ping file. A temporary file will be written first,
1.80 + * and then moved to the destination file location specified by the caller.
1.81 + *
1.82 + * The directory for writing the temporary file is highly suggested to be the Android internal cache directory,
1.83 + * fetched by <code>context.getCacheDir()</code>
1.84 + *
1.85 + * If the destination file already exists, it will be deleted and overwritten.
1.86 + *
1.87 + * Default charset: "us-ascii"
1.88 + * Default block size: uses constructor default of 8192 bytes (see javadocs for
1.89 + * <code>BufferedOutputStream</code>
1.90 + * @param parentPath
1.91 + * path of parent directory of ping file to be written
1.92 + * @param cacheDir
1.93 + * path of cache directory for writing temporary files.
1.94 + * @param filename
1.95 + * name of ping file to be written
1.96 + */
1.97 + public TelemetryRecorder(File parentDir, File cacheDir, String filename) {
1.98 + if (!parentDir.isDirectory()) {
1.99 + throw new IllegalArgumentException("Expecting directory, got non-directory File instead.");
1.100 + }
1.101 + this.parentDir = parentDir;
1.102 + this.filename = filename;
1.103 + this.cacheDir = cacheDir;
1.104 + }
1.105 +
1.106 + public TelemetryRecorder(File parentDir, File cacheDir, String filename, String charset) {
1.107 + this(parentDir, cacheDir, filename);
1.108 + this.charset = charset;
1.109 + }
1.110 +
1.111 + public TelemetryRecorder(File parentDir, File cacheDir, String filename, String charset, int blockSize) {
1.112 + this(parentDir, cacheDir, filename, charset);
1.113 + this.blockSize = blockSize;
1.114 + }
1.115 +
1.116 + /**
1.117 + * Start the temporary ping file and write the "slug" header and payload key, of the
1.118 + * format:
1.119 + *
1.120 + * { "slug": "< filename >", "payload":
1.121 + *
1.122 + * @throws Exception
1.123 + * Checked exceptions <code>NoSuchAlgorithmException</code>,
1.124 + * <code>UnsupportedEncodingException</code>, or
1.125 + * <code>IOException</code> and unchecked exception that
1.126 + * are rethrown to caller
1.127 + */
1.128 + public void startPingFile() throws Exception {
1.129 +
1.130 + // Open stream to temporary file for writing.
1.131 + try {
1.132 + tmpFile = File.createTempFile(filename, "tmp", cacheDir);
1.133 + } catch (IOException e) {
1.134 + // Try to create the temporary file in the ping directory.
1.135 + tmpFile = new File(parentDir, filename + ".tmp");
1.136 + try {
1.137 + tmpFile.createNewFile();
1.138 + } catch (IOException e1) {
1.139 + cleanUpAndRethrow("Failed to create tmp file in temp directory or ping directory.", e1);
1.140 + }
1.141 + }
1.142 +
1.143 + try {
1.144 + if (blockSize > 0) {
1.145 + outputStream = new BufferedOutputStream(new FileOutputStream(tmpFile), blockSize);
1.146 + } else {
1.147 + outputStream = new BufferedOutputStream(new FileOutputStream(tmpFile));
1.148 + }
1.149 +
1.150 + // Create checksum for ping.
1.151 + checksum = MessageDigest.getInstance("SHA-256");
1.152 +
1.153 + // Write ping header.
1.154 + byte[] header = makePingHeader(filename);
1.155 + outputStream.write(header);
1.156 + Logger.debug(LOG_TAG, "Wrote " + header.length + " header bytes.");
1.157 +
1.158 + } catch (NoSuchAlgorithmException e) {
1.159 + cleanUpAndRethrow("Error creating checksum digest", e);
1.160 + } catch (UnsupportedEncodingException e) {
1.161 + cleanUpAndRethrow("Error writing header", e);
1.162 + } catch (IOException e) {
1.163 + cleanUpAndRethrow("Error writing to stream", e);
1.164 + }
1.165 + }
1.166 +
1.167 + private byte[] makePingHeader(String slug)
1.168 + throws UnsupportedEncodingException {
1.169 + return ("{\"slug\":" + JSONObject.quote(slug) + "," + "\"payload\":\"")
1.170 + .getBytes(charset);
1.171 + }
1.172 +
1.173 + /**
1.174 + * Append payloadContent to ping file and update the checksum.
1.175 + *
1.176 + * @param payloadContent
1.177 + * String content to be written
1.178 + * @return number of bytes written, or -1 if writing failed
1.179 + * @throws Exception
1.180 + * Checked exceptions <code>UnsupportedEncodingException</code> or
1.181 + * <code>IOException</code> and unchecked exception that
1.182 + * are rethrown to caller
1.183 + */
1.184 + public int appendPayload(String payloadContent) throws Exception {
1.185 + if (payloadContent == null) {
1.186 + cleanUpAndRethrow("Payload is null", new Exception());
1.187 + return -1;
1.188 + }
1.189 +
1.190 + try {
1.191 + byte[] payloadBytes = payloadContent.getBytes(charset);
1.192 + // If we run into an error, we'll throw and abort, so checksum won't be stale.
1.193 + checksum.update(payloadBytes);
1.194 +
1.195 + byte[] quotedPayloadBytes = JSONObject.quote(payloadContent).getBytes(charset);
1.196 +
1.197 + // First and last bytes are quotes inserted by JSONObject.quote; discard
1.198 + // them.
1.199 + int numBytes = quotedPayloadBytes.length - 2;
1.200 + outputStream.write(quotedPayloadBytes, 1, numBytes);
1.201 + return numBytes;
1.202 +
1.203 + } catch (UnsupportedEncodingException e) {
1.204 + cleanUpAndRethrow("Error encoding payload", e);
1.205 + return -1;
1.206 + } catch (IOException e) {
1.207 + cleanUpAndRethrow("Error writing to stream", e);
1.208 + return -1;
1.209 + }
1.210 + }
1.211 +
1.212 + /**
1.213 + * Add the checksum of the payload to the ping file and close the stream.
1.214 + *
1.215 + * @throws Exception
1.216 + * Checked exceptions <code>UnsupportedEncodingException</code> or
1.217 + * <code>IOException</code> and unchecked exception that
1.218 + * are rethrown to caller
1.219 + */
1.220 + public void finishPingFile() throws Exception {
1.221 + try {
1.222 + byte[] footer = makePingFooter(checksum);
1.223 + outputStream.write(footer);
1.224 + // We're done writing, so force the stream to flush the buffer.
1.225 + outputStream.flush();
1.226 + Logger.debug(LOG_TAG, "Wrote " + footer.length + " footer bytes.");
1.227 + } catch (UnsupportedEncodingException e) {
1.228 + cleanUpAndRethrow("Checksum encoding exception", e);
1.229 + } catch (IOException e) {
1.230 + cleanUpAndRethrow("Error writing footer to stream", e);
1.231 + } finally {
1.232 + try {
1.233 + outputStream.close();
1.234 + } catch (IOException e) {
1.235 + // Failed to close, nothing we can do except discard the reference to the stream.
1.236 + outputStream = null;
1.237 + }
1.238 + }
1.239 +
1.240 + // Move temp file to destination specified by caller.
1.241 + try {
1.242 + File destFile = new File(parentDir, filename);
1.243 + // Delete file if it exists - docs state that rename may fail if the File already exists.
1.244 + if (destFile.exists()) {
1.245 + destFile.delete();
1.246 + }
1.247 + boolean result = tmpFile.renameTo(destFile);
1.248 + if (!result) {
1.249 + throw new IOException("Could not move tmp file to destination.");
1.250 + }
1.251 + } finally {
1.252 + cleanUp();
1.253 + }
1.254 + }
1.255 +
1.256 + private byte[] makePingFooter(MessageDigest checksum)
1.257 + throws UnsupportedEncodingException {
1.258 + base64Checksum = Base64.encodeToString(checksum.digest(), Base64.NO_WRAP);
1.259 + return ("\",\"checksum\":" + JSONObject.quote(base64Checksum) + "}")
1.260 + .getBytes(charset);
1.261 + }
1.262 +
1.263 + /**
1.264 + * Get final digested Base64 checksum.
1.265 + *
1.266 + * @return String checksum if it has been calculated, null otherwise.
1.267 + */
1.268 + protected String getFinalChecksum() {
1.269 + return base64Checksum;
1.270 + }
1.271 +
1.272 + public String getCharset() {
1.273 + return this.charset;
1.274 + }
1.275 +
1.276 + /**
1.277 + * Clean up checksum and delete the temporary file.
1.278 + */
1.279 + private void cleanUp() {
1.280 + // Discard checksum.
1.281 + checksum.reset();
1.282 +
1.283 + // Clean up files.
1.284 + if (tmpFile != null && tmpFile.exists()) {
1.285 + tmpFile.delete();
1.286 + }
1.287 + tmpFile = null;
1.288 + }
1.289 +
1.290 + /**
1.291 + * Log message and error and clean up, then rethrow exception to caller.
1.292 + *
1.293 + * @param message
1.294 + * Error message
1.295 + * @param e
1.296 + * Exception
1.297 + *
1.298 + * @throws Exception
1.299 + * Exception to be rethrown to caller
1.300 + */
1.301 + private void cleanUpAndRethrow(String message, Exception e) throws Exception {
1.302 + Logger.error(LOG_TAG, message, e);
1.303 + cleanUp();
1.304 +
1.305 + if (outputStream != null) {
1.306 + try {
1.307 + outputStream.close();
1.308 + } catch (IOException exception) {
1.309 + // Failed to close stream; nothing we can do, and we're aborting anyways.
1.310 + }
1.311 + }
1.312 +
1.313 + if (destFile != null && destFile.exists()) {
1.314 + destFile.delete();
1.315 + }
1.316 + // Rethrow the exception.
1.317 + throw e;
1.318 + }
1.319 +}
