/*
* Copyright 2012 Google Inc.
*
* 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 com.google.android.gcm.server;
import static com.google.android.gcm.server.Constants.GCM_SEND_ENDPOINT;
import static com.google.android.gcm.server.Constants.JSON_CANONICAL_IDS;
import static com.google.android.gcm.server.Constants.JSON_ERROR;
import static com.google.android.gcm.server.Constants.JSON_FAILURE;
import static com.google.android.gcm.server.Constants.JSON_MESSAGE_ID;
import static com.google.android.gcm.server.Constants.JSON_MULTICAST_ID;
import static com.google.android.gcm.server.Constants.JSON_PAYLOAD;
import static com.google.android.gcm.server.Constants.JSON_REGISTRATION_IDS;
import static com.google.android.gcm.server.Constants.JSON_RESULTS;
import static com.google.android.gcm.server.Constants.JSON_SUCCESS;
import static com.google.android.gcm.server.Constants.PARAM_COLLAPSE_KEY;
import static com.google.android.gcm.server.Constants.PARAM_DELAY_WHILE_IDLE;
import static com.google.android.gcm.server.Constants.PARAM_PAYLOAD_PREFIX;
import static com.google.android.gcm.server.Constants.PARAM_REGISTRATION_ID;
import static com.google.android.gcm.server.Constants.PARAM_TIME_TO_LIVE;
import static com.google.android.gcm.server.Constants.TOKEN_CANONICAL_REG_ID;
import static com.google.android.gcm.server.Constants.TOKEN_ERROR;
import static com.google.android.gcm.server.Constants.TOKEN_MESSAGE_ID;
import com.google.android.gcm.server.Result.Builder;
import org.json.simple.JSONObject;
import org.json.simple.JSONValue;
import org.json.simple.parser.JSONParser;
import org.json.simple.parser.ParseException;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Random;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Helper class to send messages to the GCM service using an API Key.
*/
public class Sender {
protected static final String UTF8 = "UTF-8";
/**
* Initial delay before first retry, without jitter.
*/
protected static final int BACKOFF_INITIAL_DELAY = 1000;
/**
* Maximum delay before a retry.
*/
protected static final int MAX_BACKOFF_DELAY = 1024000;
protected final Random random = new Random();
protected final Logger logger = Logger.getLogger(getClass().getName());
private final String key;
/**
* Default constructor.
*
* @param key API key obtained through the Google API Console.
*/
public Sender(String key) {
this.key = nonNull(key);
}
/**
* Sends a message to one device, retrying in case of unavailability.
*
* <p>
* <strong>Note: </strong> this method uses exponential back-off to retry in
* case of service unavailability and hence could block the calling thread
* for many seconds.
*
* @param message message to be sent, including the device's registration id.
* @param registrationId device where the message will be sent.
* @param retries number of retries in case of service unavailability errors.
*
* @return result of the request (see its javadoc for more details)
*
* @throws IllegalArgumentException if registrationId is {@literal null}.
* @throws InvalidRequestException if GCM didn't returned a 200 or 503 status.
* @throws IOException if message could not be sent.
*/
public Result send(Message message, String registrationId, int retries)
throws IOException {
int attempt = 0;
Result result = null;
int backoff = BACKOFF_INITIAL_DELAY;
boolean tryAgain;
do {
attempt++;
if (logger.isLoggable(Level.FINE)) {
logger.fine("Attempt #" + attempt + " to send message " +
message + " to regIds " + registrationId);
}
result = sendNoRetry(message, registrationId);
tryAgain = result == null && attempt <= retries;
if (tryAgain) {
int sleepTime = backoff / 2 + random.nextInt(backoff);
sleep(sleepTime);
if (2 * backoff < MAX_BACKOFF_DELAY) {
backoff *= 2;
}
}
} while (tryAgain);
if (result == null) {
throw new IOException("Could not send message after " + attempt +
" attempts");
}
return result;
}
/**
* Sends a message without retrying in case of service unavailability. See
* {@link #send(Message, String, int)} for more info.
*
* @return result of the post, or {@literal null} if the GCM service was
* unavailable.
*
* @throws InvalidRequestException if GCM didn't returned a 200 or 503 status.
* @throws IllegalArgumentException if registrationId is {@literal null}.
*/
public Result sendNoRetry(Message message, String registrationId)
throws IOException {
StringBuilder body = newBody(PARAM_REGISTRATION_ID, registrationId);
Boolean delayWhileIdle = message.isDelayWhileIdle();
if (delayWhileIdle != null) {
addParameter(body, PARAM_DELAY_WHILE_IDLE, delayWhileIdle ? "1" : "0");
}
String collapseKey = message.getCollapseKey();
if (collapseKey != null) {
addParameter(body, PARAM_COLLAPSE_KEY, collapseKey);
}
Integer timeToLive = message.getTimeToLive();
if (timeToLive != null) {
addParameter(body, PARAM_TIME_TO_LIVE, Integer.toString(timeToLive));
}
for (Entry<String, String> entry : message.getData().entrySet()) {
String key = PARAM_PAYLOAD_PREFIX + entry.getKey();
String value = entry.getValue();
addParameter(body, key, URLEncoder.encode(value, UTF8));
}
String requestBody = body.toString();
logger.finest("Request body: " + requestBody);
HttpURLConnection conn = post(GCM_SEND_ENDPOINT, requestBody);
int status = conn.getResponseCode();
if (status == 503) {
logger.fine("GCM service is unavailable");
return null;
}
if (status != 200) {
throw new InvalidRequestException(status);
}
try {
BufferedReader reader =
new BufferedReader(new InputStreamReader(conn.getInputStream()));
try {
String line = reader.readLine();
if (line == null || line.equals("")) {
throw new IOException("Received empty response from GCM service.");
}
String[] responseParts = split(line);
String token = responseParts[0];
String value = responseParts[1];
if (token.equals(TOKEN_MESSAGE_ID)) {
Builder builder = new Result.Builder().messageId(value);
// check for canonical registration id
line = reader.readLine();
if (line != null) {
responseParts = split(line);
token = responseParts[0];
value = responseParts[1];
if (token.equals(TOKEN_CANONICAL_REG_ID)) {
builder.canonicalRegistrationId(value);
} else {
logger.warning("Received invalid second line from GCM: " + line);
}
}
Result result = builder.build();
if (logger.isLoggable(Level.FINE)) {
logger.fine("Message created succesfully (" + result + ")");
}
return result;
} else if (token.equals(TOKEN_ERROR)) {
return new Result.Builder().errorCode(value).build();
} else {
throw new IOException("Received invalid response from GCM: " + line);
}
} finally {
reader.close();
}
} finally {
conn.disconnect();
}
}
/**
* Sends a message to many devices, retrying in case of unavailability.
*
* <p>
* <strong>Note: </strong> this method uses exponential back-off to retry in
* case of service unavailability and hence could block the calling thread
* for many seconds.
*
* @param message message to be sent.
* @param regIds registration id of the devices that will receive
* the message.
* @param retries number of retries in case of service unavailability errors.
*
* @return combined result of all requests made.
*
* @throws IllegalArgumentException if registrationIds is {@literal null} or
* empty.
* @throws InvalidRequestException if GCM didn't returned a 200 or 503 status.
* @throws IOException if message could not be sent.
*/
public MulticastResult send(Message message, List<String> regIds, int retries)
throws IOException {
int attempt = 0;
MulticastResult multicastResult = null;
int backoff = BACKOFF_INITIAL_DELAY;
// Map of results by registration id, it will be updated after each attempt
// to send the messages
Map<String, Result> results = new HashMap<String, Result>();
List<String> unsentRegIds = new ArrayList<String>(regIds);
boolean tryAgain;
List<Long> multicastIds = new ArrayList<Long>();
do {
attempt++;
if (logger.isLoggable(Level.FINE)) {
logger.fine("Attempt #" + attempt + " to send message " +
message + " to regIds " + unsentRegIds);
}
multicastResult = sendNoRetry(message, unsentRegIds);
long multicastId = multicastResult.getMulticastId();
logger.fine("multicast_id on attempt # " + attempt + ": " +
multicastId);
multicastIds.add(multicastId);
unsentRegIds = updateStatus(unsentRegIds, results, multicastResult);
tryAgain = !unsentRegIds.isEmpty() && attempt <= retries;
if (tryAgain) {
int sleepTime = backoff / 2 + random.nextInt(backoff);
sleep(sleepTime);
if (2 * backoff < MAX_BACKOFF_DELAY) {
backoff *= 2;
}
}
} while (tryAgain);
// calculate summary
int success = 0, failure = 0 , canonicalIds = 0;
for (Result result : results.values()) {
if (result.getMessageId() != null) {
success++;
if (result.getCanonicalRegistrationId() != null) {
canonicalIds++;
}
} else {
failure++;
}
}
// build a new object with the overall result
long multicastId = multicastIds.remove(0);
MulticastResult.Builder builder = new MulticastResult.Builder(success,
failure, canonicalIds, multicastId).retryMulticastIds(multicastIds);
// add results, in the same order as the input
for (String regId : regIds) {
Result result = results.get(regId);
builder.addResult(result);
}
return builder.build();
}
/**
* Updates the status of the messages sent to devices and the list of devices
* that should be retried.
*
* @param unsentRegIds list of devices that are still pending an update.
* @param allResults map of status that will be updated.
* @param multicastResult result of the last multicast sent.
*
* @return updated version of devices that should be retried.
*/
private List<String> updateStatus(List<String> unsentRegIds,
Map<String, Result> allResults, MulticastResult multicastResult) {
List<Result> results = multicastResult.getResults();
if (results.size() != unsentRegIds.size()) {
// should never happen, unless there is a flaw in the algorithm
throw new RuntimeException("Internal error: sizes do not match. " +
"currentResults: " + results + "; unsentRegIds: " + unsentRegIds);
}
List<String> newUnsentRegIds = new ArrayList<String>();
for (int i = 0; i < unsentRegIds.size(); i++) {
String regId = unsentRegIds.get(i);
Result result = results.get(i);
allResults.put(regId, result);
String error = result.getErrorCodeName();
if (error != null && error.equals(Constants.ERROR_UNAVAILABLE)) {
newUnsentRegIds.add(regId);
}
}
return newUnsentRegIds;
}
/**
* Sends a message without retrying in case of service unavailability. See
* {@link #send(Message, List, int)} for more info.
*
* @return {@literal true} if the message was sent successfully,
* {@literal false} if it failed but could be retried.
*
* @throws IllegalArgumentException if registrationIds is {@literal null} or
* empty.
* @throws InvalidRequestException if GCM didn't returned a 200 status.
* @throws IOException if message could not be sent or received.
*/
public MulticastResult sendNoRetry(Message message,
List<String> registrationIds) throws IOException {
if (nonNull(registrationIds).isEmpty()) {
throw new IllegalArgumentException("registrationIds cannot be empty");
}
Map<Object, Object> jsonRequest = new HashMap<Object, Object>();
setJsonField(jsonRequest, PARAM_TIME_TO_LIVE, message.getTimeToLive());
setJsonField(jsonRequest, PARAM_COLLAPSE_KEY, message.getCollapseKey());
setJsonField(jsonRequest, PARAM_DELAY_WHILE_IDLE,
message.isDelayWhileIdle());
jsonRequest.put(JSON_REGISTRATION_IDS, registrationIds);
Map<String, String> payload = message.getData();
if (!payload.isEmpty()) {
jsonRequest.put(JSON_PAYLOAD, payload);
}
String requestBody = JSONValue.toJSONString(jsonRequest);
logger.finest("JSON request: " + requestBody);
HttpURLConnection conn =
post(GCM_SEND_ENDPOINT, "application/json", requestBody);
int status = conn.getResponseCode();
String responseBody;
if (status != 200) {
if (status == 401) {
throw new InvalidRequestException(status);
}
if (status == 503) {
throw new UnknownHostException();
}
}
responseBody = getString(conn.getInputStream());
logger.finest("JSON response: " + responseBody);
JSONParser parser = new JSONParser();
JSONObject jsonResponse;
try {
jsonResponse = (JSONObject) parser.parse(responseBody);
int success = getNumber(jsonResponse, JSON_SUCCESS).intValue();
int failure = getNumber(jsonResponse, JSON_FAILURE).intValue();
int canonicalIds = getNumber(jsonResponse, JSON_CANONICAL_IDS).intValue();
long multicastId = getNumber(jsonResponse, JSON_MULTICAST_ID).longValue();
MulticastResult.Builder builder = new MulticastResult.Builder(success,
failure, canonicalIds, multicastId);
@SuppressWarnings("unchecked")
List<Map<String, Object>> results =
(List<Map<String, Object>>) jsonResponse.get(JSON_RESULTS);
if (results != null) {
for (Map<String, Object> jsonResult : results) {
String messageId = (String) jsonResult.get(JSON_MESSAGE_ID);
String canonicalRegId =
(String) jsonResult.get(TOKEN_CANONICAL_REG_ID);
String error = (String) jsonResult.get(JSON_ERROR);
Result result = new Result.Builder()
.messageId(messageId)
.canonicalRegistrationId(canonicalRegId)
.errorCode(error)
.build();
builder.addResult(result);
}
}
MulticastResult multicastResult = builder.build();
return multicastResult;
} catch (ParseException e) {
throw newIoException(responseBody, e);
} catch (CustomParserException e) {
throw newIoException(responseBody, e);
}
}
private IOException newIoException(String responseBody, Exception e) {
// log exception, as IOException constructor that takes a message and cause
// is only available on Java 6
String msg = "Error parsing JSON response (" + responseBody + ")";
logger.log(Level.WARNING, msg, e);
return new IOException(msg + ":" + e);
}
/**
* Sets a JSON field, but only if the value is not {@literal null}.
*/
private void setJsonField(Map<Object, Object> json, String field,
Object value) {
if (value != null) {
json.put(field, value);
}
}
private Number getNumber(Map<?, ?> json, String field) {
Object value = json.get(field);
if (value == null) {
throw new CustomParserException("Missing field: " + field);
}
if (!(value instanceof Number)) {
throw new CustomParserException("Field " + field +
" does not contain a number: " + value);
}
return (Number) value;
}
class CustomParserException extends RuntimeException {
CustomParserException(String message) {
super(message);
}
}
private String[] split(String line) throws IOException {
String[] split = line.split("=", 2);
if (split.length != 2) {
throw new IOException("Received invalid response line from GCM: " + line);
}
return split;
}
/**
* Make an HTTP post to a given URL.
*
* @return HTTP response.
*/
protected HttpURLConnection post(String url, String body)
throws IOException {
return post(url, "application/x-www-form-urlencoded;charset=UTF-8", body);
}
protected HttpURLConnection post(String url, String contentType, String body)
throws IOException {
if (url == null || body == null) {
throw new IllegalArgumentException("arguments cannot be null");
}
if (!url.startsWith("https://")) {
logger.warning("URL does not use https: " + url);
}
logger.fine("Sending POST to " + url);
logger.finest("POST body: " + body);
byte[] bytes = body.getBytes();
HttpURLConnection conn = getConnection(url);
conn.setDoOutput(true);
conn.setUseCaches(false);
conn.setFixedLengthStreamingMode(bytes.length);
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type", contentType);
conn.setRequestProperty("Authorization", "key=" + key);
OutputStream out = conn.getOutputStream();
out.write(bytes);
out.close();
return conn;
}
/**
* Creates a map with just one key-value pair.
*/
protected static final Map<String, String> newKeyValues(String key,
String value) {
Map<String, String> keyValues = new HashMap<String, String>(1);
keyValues.put(nonNull(key), nonNull(value));
return keyValues;
}
/**
* Creates a {@link StringBuilder} to be used as the body of an HTTP POST.
*
* @param name initial parameter for the POST.
* @param value initial value for that parameter.
* @return StringBuilder to be used an HTTP POST body.
*/
protected static StringBuilder newBody(String name, String value) {
return new StringBuilder(nonNull(name)).append('=').append(nonNull(value));
}
/**
* Adds a new parameter to the HTTP POST body.
*
* @param body HTTP POST body
* @param name parameter's name
* @param value parameter's value
*/
protected static void addParameter(StringBuilder body, String name,
String value) {
nonNull(body).append('&')
.append(nonNull(name)).append('=').append(nonNull(value));
}
/**
* Gets an {@link HttpURLConnection} given an URL.
*/
protected HttpURLConnection getConnection(String url) throws IOException {
HttpURLConnection conn = (HttpURLConnection) new URL(url).openConnection();
return conn;
}
/**
* Convenience method to convert an InputStream to a String.
*
* <p>
* If the stream ends in a newline character, it will be stripped.
*/
protected static String getString(InputStream stream) throws IOException {
BufferedReader reader =
new BufferedReader(new InputStreamReader(nonNull(stream)));
StringBuilder content = new StringBuilder();
String newLine;
do {
newLine = reader.readLine();
if (newLine != null) {
content.append(newLine).append('\n');
}
} while (newLine != null);
if (content.length() > 0) {
// strip last newline
content.setLength(content.length() - 1);
}
return content.toString();
}
static <T> T nonNull(T argument) {
if (argument == null) {
throw new IllegalArgumentException("argument cannot be null");
}
return argument;
}
void sleep(long millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}