| /* |
| * Copyright (C) 2015 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 com.android.statementservice.retriever; |
| |
| import android.util.Log; |
| |
| import com.android.volley.Cache; |
| import com.android.volley.NetworkResponse; |
| import com.android.volley.toolbox.HttpHeaderParser; |
| |
| import java.io.BufferedInputStream; |
| import java.io.ByteArrayOutputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| import java.net.HttpURLConnection; |
| import java.net.URL; |
| import java.util.HashMap; |
| import java.util.List; |
| import java.util.Locale; |
| import java.util.Map; |
| |
| /** |
| * Helper class for fetching HTTP or HTTPS URL. |
| * |
| * Visible for testing. |
| * |
| * @hide |
| */ |
| public class URLFetcher { |
| private static final String TAG = URLFetcher.class.getSimpleName(); |
| |
| private static final long DO_NOT_CACHE_RESULT = 0L; |
| private static final int INPUT_BUFFER_SIZE_IN_BYTES = 1024; |
| |
| /** |
| * Fetches the specified url and returns the content and ttl. |
| * |
| * <p> |
| * Retry {@code retry} times if the connection failed or timed out for any reason. |
| * HTTP error code (e.g. 404/500) won't be retried. |
| * |
| * @throws IOException if it can't retrieve the content due to a network problem. |
| * @throws AssociationServiceException if the URL scheme is not http or https or the content |
| * length exceeds {code fileSizeLimit}. |
| */ |
| public WebContent getWebContentFromUrlWithRetry(URL url, long fileSizeLimit, |
| int connectionTimeoutMillis, int backoffMillis, int retry) |
| throws AssociationServiceException, IOException, InterruptedException { |
| if (retry <= 0) { |
| throw new IllegalArgumentException("retry should be a postive inetger."); |
| } |
| while (retry > 0) { |
| try { |
| return getWebContentFromUrl(url, fileSizeLimit, connectionTimeoutMillis); |
| } catch (IOException e) { |
| retry--; |
| if (retry == 0) { |
| throw e; |
| } |
| } |
| |
| Thread.sleep(backoffMillis); |
| } |
| |
| // Should never reach here. |
| return null; |
| } |
| |
| /** |
| * Fetches the specified url and returns the content and ttl. |
| * |
| * @throws IOException if it can't retrieve the content due to a network problem. |
| * @throws AssociationServiceException if the URL scheme is not http or https or the content |
| * length exceeds {code fileSizeLimit}. |
| */ |
| public WebContent getWebContentFromUrl(URL url, long fileSizeLimit, int connectionTimeoutMillis) |
| throws AssociationServiceException, IOException { |
| final String scheme = url.getProtocol().toLowerCase(Locale.US); |
| if (!scheme.equals("http") && !scheme.equals("https")) { |
| throw new IllegalArgumentException("The url protocol should be on http or https."); |
| } |
| |
| HttpURLConnection connection = null; |
| try { |
| connection = (HttpURLConnection) url.openConnection(); |
| connection.setInstanceFollowRedirects(true); |
| connection.setConnectTimeout(connectionTimeoutMillis); |
| connection.setReadTimeout(connectionTimeoutMillis); |
| connection.setUseCaches(true); |
| connection.setInstanceFollowRedirects(false); |
| connection.addRequestProperty("Cache-Control", "max-stale=60"); |
| |
| if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) { |
| Log.e(TAG, "The responses code is not 200 but " + connection.getResponseCode()); |
| return new WebContent("", DO_NOT_CACHE_RESULT); |
| } |
| |
| if (connection.getContentLength() > fileSizeLimit) { |
| Log.e(TAG, "The content size of the url is larger than " + fileSizeLimit); |
| return new WebContent("", DO_NOT_CACHE_RESULT); |
| } |
| |
| Long expireTimeMillis = getExpirationTimeMillisFromHTTPHeader( |
| connection.getHeaderFields()); |
| |
| return new WebContent(inputStreamToString( |
| connection.getInputStream(), connection.getContentLength(), fileSizeLimit), |
| expireTimeMillis); |
| } finally { |
| if (connection != null) { |
| connection.disconnect(); |
| } |
| } |
| } |
| |
| /** |
| * Visible for testing. |
| * @hide |
| */ |
| public static String inputStreamToString(InputStream inputStream, int length, long sizeLimit) |
| throws IOException, AssociationServiceException { |
| if (length < 0) { |
| length = 0; |
| } |
| ByteArrayOutputStream baos = new ByteArrayOutputStream(length); |
| BufferedInputStream bis = new BufferedInputStream(inputStream); |
| byte[] buffer = new byte[INPUT_BUFFER_SIZE_IN_BYTES]; |
| int len = 0; |
| while ((len = bis.read(buffer)) != -1) { |
| baos.write(buffer, 0, len); |
| if (baos.size() > sizeLimit) { |
| throw new AssociationServiceException("The content size of the url is larger than " |
| + sizeLimit); |
| } |
| } |
| return baos.toString("UTF-8"); |
| } |
| |
| /** |
| * Parses the HTTP headers to compute the ttl. |
| * |
| * @param headers a map that map the header key to the header values. Can be null. |
| * @return the ttl in millisecond or null if the ttl is not specified in the header. |
| */ |
| private Long getExpirationTimeMillisFromHTTPHeader(Map<String, List<String>> headers) { |
| if (headers == null) { |
| return null; |
| } |
| Map<String, String> joinedHeaders = joinHttpHeaders(headers); |
| |
| NetworkResponse response = new NetworkResponse(null, joinedHeaders); |
| Cache.Entry cachePolicy = HttpHeaderParser.parseCacheHeaders(response); |
| |
| if (cachePolicy == null) { |
| // Cache is disabled, set the expire time to 0. |
| return DO_NOT_CACHE_RESULT; |
| } else if (cachePolicy.ttl == 0) { |
| // Cache policy is not specified, set the expire time to 0. |
| return DO_NOT_CACHE_RESULT; |
| } else { |
| // cachePolicy.ttl is actually the expire timestamp in millisecond. |
| return cachePolicy.ttl; |
| } |
| } |
| |
| /** |
| * Converts an HTTP header map of the format provided by {@linkHttpUrlConnection} to a map of |
| * the format accepted by {@link HttpHeaderParser}. It does this by joining all the entries for |
| * a given header key with ", ". |
| */ |
| private Map<String, String> joinHttpHeaders(Map<String, List<String>> headers) { |
| Map<String, String> joinedHeaders = new HashMap<String, String>(); |
| for (Map.Entry<String, List<String>> entry : headers.entrySet()) { |
| List<String> values = entry.getValue(); |
| if (values.size() == 1) { |
| joinedHeaders.put(entry.getKey(), values.get(0)); |
| } else { |
| joinedHeaders.put(entry.getKey(), Utils.joinStrings(", ", values)); |
| } |
| } |
| return joinedHeaders; |
| } |
| } |