1 /* 2 * Copyright (C) 2023 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.adservices.service.measurement.registration; 18 19 import android.net.Uri; 20 21 import java.util.ArrayList; 22 import java.util.List; 23 import java.util.Map; 24 25 /** Class for handling redirects */ 26 public class AsyncRedirects { 27 public static final String HEADER_ATTRIBUTION_REPORTING_REDIRECT_CONFIG = 28 "Attribution-Reporting-Redirect-Config"; 29 public static final String REDIRECT_302_TO_WELL_KNOWN = "redirect-302-to-well-known"; 30 public static final String WELL_KNOWN_PATH_SEGMENT = 31 ".well-known/attribution-reporting/register-redirect"; 32 public static final String WELL_KNOWN_QUERY_PARAM = "302_url"; 33 public static final String REDIRECT_LIST_HEADER_KEY = "Attribution-Reporting-Redirect"; 34 public static final String REDIRECT_LOCATION_HEADER_KEY = "Location"; 35 private final List<AsyncRedirect> mLocationRedirects; 36 private final List<AsyncRedirect> mListRedirects; 37 AsyncRedirects()38 public AsyncRedirects() { 39 mLocationRedirects = new ArrayList<>(); 40 mListRedirects = new ArrayList<>(); 41 } 42 43 /** Return flattened list of {@link AsyncRedirect} */ getRedirects()44 public List<AsyncRedirect> getRedirects() { 45 List<AsyncRedirect> allRedirects = new ArrayList<>(mListRedirects); 46 allRedirects.addAll(mLocationRedirects); 47 48 return allRedirects; 49 } 50 51 /** Get list of {@link AsyncRedirect} by redirect type */ getRedirectsByType(AsyncRegistration.RedirectType redirectType)52 public List<AsyncRedirect> getRedirectsByType(AsyncRegistration.RedirectType redirectType) { 53 if (redirectType == AsyncRegistration.RedirectType.LOCATION) { 54 return new ArrayList<>(mLocationRedirects); 55 } else { 56 return new ArrayList<>(mListRedirects); 57 } 58 } 59 60 /** Process redirects based on the given headers */ configure(Map<String, List<String>> headers, AsyncRegistration parentRegistration)61 public void configure(Map<String, List<String>> headers, AsyncRegistration parentRegistration) { 62 if (!parentRegistration.shouldProcessRedirects()) { 63 return; 64 } 65 66 Map<AsyncRegistration.RedirectType, List<Uri>> urisByType = 67 FetcherUtil.parseRedirects(headers); 68 69 for (Uri locationRedirectUri : urisByType.get(AsyncRegistration.RedirectType.LOCATION)) { 70 if (shouldRedirect302ToWellKnown(headers, parentRegistration)) { 71 mLocationRedirects.add( 72 new AsyncRedirect( 73 getLocationRedirectToWellKnownUri(locationRedirectUri), 74 AsyncRedirect.RedirectBehavior.LOCATION_TO_WELL_KNOWN)); 75 } else { 76 mLocationRedirects.add( 77 new AsyncRedirect( 78 locationRedirectUri, AsyncRedirect.RedirectBehavior.AS_IS)); 79 } 80 } 81 82 for (Uri listRedirectUri : urisByType.get(AsyncRegistration.RedirectType.LIST)) { 83 mListRedirects.add( 84 new AsyncRedirect(listRedirectUri, AsyncRedirect.RedirectBehavior.AS_IS)); 85 } 86 } 87 shouldRedirect302ToWellKnown( Map<String, List<String>> headers, AsyncRegistration parentRegistration)88 private static boolean shouldRedirect302ToWellKnown( 89 Map<String, List<String>> headers, AsyncRegistration parentRegistration) { 90 boolean isParentRegistrationRedirectsToWellKnown = 91 AsyncRedirect.RedirectBehavior.LOCATION_TO_WELL_KNOWN.equals( 92 parentRegistration.getRedirectBehavior()); 93 94 return isParentRegistrationRedirectsToWellKnown || isRedirect302ToWellKnownPath(headers); 95 } 96 97 /** 98 * Return true if the given headers indicate redirects should prepend well known prefix to the 99 * path. 100 */ isRedirect302ToWellKnownPath(Map<String, List<String>> headers)101 private static boolean isRedirect302ToWellKnownPath(Map<String, List<String>> headers) { 102 if (!headers.containsKey(HEADER_ATTRIBUTION_REPORTING_REDIRECT_CONFIG)) { 103 return false; 104 } 105 List<String> config = headers.get(HEADER_ATTRIBUTION_REPORTING_REDIRECT_CONFIG); 106 if (config == null || config.size() != 1) { 107 return false; 108 } 109 110 return config.get(0).equalsIgnoreCase(REDIRECT_302_TO_WELL_KNOWN); 111 } 112 getLocationRedirectToWellKnownUri(Uri redirectUri)113 private Uri getLocationRedirectToWellKnownUri(Uri redirectUri) { 114 return redirectUri 115 .buildUpon() 116 .encodedPath(WELL_KNOWN_PATH_SEGMENT) 117 .clearQuery() 118 .appendQueryParameter(WELL_KNOWN_QUERY_PARAM, redirectUri.toString()) 119 .build(); 120 } 121 } 122