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      1 /*
      2  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  *
     25  */
     26 
     27 #include "config.h"
     28 #include "core/fetch/CrossOriginAccessControl.h"
     29 
     30 #include "core/fetch/Resource.h"
     31 #include "core/fetch/ResourceLoaderOptions.h"
     32 #include "platform/network/HTTPParsers.h"
     33 #include "platform/network/ResourceRequest.h"
     34 #include "platform/network/ResourceResponse.h"
     35 #include "platform/weborigin/SchemeRegistry.h"
     36 #include "platform/weborigin/SecurityOrigin.h"
     37 #include "wtf/Threading.h"
     38 #include "wtf/text/AtomicString.h"
     39 #include "wtf/text/StringBuilder.h"
     40 
     41 namespace blink {
     42 
     43 static PassOwnPtr<HTTPHeaderSet> createAllowedCrossOriginResponseHeadersSet()
     44 {
     45     OwnPtr<HTTPHeaderSet> headerSet = adoptPtr(new HashSet<String, CaseFoldingHash>);
     46 
     47     headerSet->add("cache-control");
     48     headerSet->add("content-language");
     49     headerSet->add("content-type");
     50     headerSet->add("expires");
     51     headerSet->add("last-modified");
     52     headerSet->add("pragma");
     53 
     54     return headerSet.release();
     55 }
     56 
     57 bool isOnAccessControlResponseHeaderWhitelist(const String& name)
     58 {
     59     AtomicallyInitializedStatic(HTTPHeaderSet*, allowedCrossOriginResponseHeaders = createAllowedCrossOriginResponseHeadersSet().leakPtr());
     60 
     61     return allowedCrossOriginResponseHeaders->contains(name);
     62 }
     63 
     64 void updateRequestForAccessControl(ResourceRequest& request, SecurityOrigin* securityOrigin, StoredCredentials allowCredentials)
     65 {
     66     request.removeCredentials();
     67     request.setAllowStoredCredentials(allowCredentials == AllowStoredCredentials);
     68 
     69     if (securityOrigin)
     70         request.setHTTPOrigin(securityOrigin->toAtomicString());
     71 }
     72 
     73 ResourceRequest createAccessControlPreflightRequest(const ResourceRequest& request, SecurityOrigin* securityOrigin)
     74 {
     75     ResourceRequest preflightRequest(request.url());
     76     updateRequestForAccessControl(preflightRequest, securityOrigin, DoNotAllowStoredCredentials);
     77     preflightRequest.setHTTPMethod("OPTIONS");
     78     preflightRequest.setHTTPHeaderField("Access-Control-Request-Method", request.httpMethod());
     79     preflightRequest.setPriority(request.priority());
     80     preflightRequest.setRequestContext(request.requestContext());
     81 
     82     const HTTPHeaderMap& requestHeaderFields = request.httpHeaderFields();
     83 
     84     if (requestHeaderFields.size() > 0) {
     85         StringBuilder headerBuffer;
     86         HTTPHeaderMap::const_iterator it = requestHeaderFields.begin();
     87         headerBuffer.append(it->key);
     88         ++it;
     89 
     90         HTTPHeaderMap::const_iterator end = requestHeaderFields.end();
     91         for (; it != end; ++it) {
     92             headerBuffer.appendLiteral(", ");
     93             headerBuffer.append(it->key);
     94         }
     95 
     96         preflightRequest.setHTTPHeaderField("Access-Control-Request-Headers", AtomicString(headerBuffer.toString().lower()));
     97     }
     98 
     99     return preflightRequest;
    100 }
    101 
    102 static bool isOriginSeparator(UChar ch)
    103 {
    104     return isASCIISpace(ch) || ch == ',';
    105 }
    106 
    107 static bool isInterestingStatusCode(int statusCode)
    108 {
    109     // Predicate that gates what status codes should be included in
    110     // console error messages for responses containing no access
    111     // control headers.
    112     return statusCode >= 400;
    113 }
    114 
    115 bool passesAccessControlCheck(const ResourceResponse& response, StoredCredentials includeCredentials, SecurityOrigin* securityOrigin, String& errorDescription)
    116 {
    117     AtomicallyInitializedStatic(AtomicString&, accessControlAllowOrigin = *new AtomicString("access-control-allow-origin", AtomicString::ConstructFromLiteral));
    118     AtomicallyInitializedStatic(AtomicString&, accessControlAllowCredentials = *new AtomicString("access-control-allow-credentials", AtomicString::ConstructFromLiteral));
    119 
    120     if (!response.httpStatusCode()) {
    121         errorDescription = "Received an invalid response. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
    122         return false;
    123     }
    124 
    125     const AtomicString& accessControlOriginString = response.httpHeaderField(accessControlAllowOrigin);
    126     if (accessControlOriginString == starAtom) {
    127         // A wildcard Access-Control-Allow-Origin can not be used if credentials are to be sent,
    128         // even with Access-Control-Allow-Credentials set to true.
    129         if (includeCredentials == DoNotAllowStoredCredentials)
    130             return true;
    131         if (response.isHTTP()) {
    132             errorDescription = "A wildcard '*' cannot be used in the 'Access-Control-Allow-Origin' header when the credentials flag is true. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
    133             return false;
    134         }
    135     } else if (accessControlOriginString != securityOrigin->toAtomicString()) {
    136         if (accessControlOriginString.isEmpty()) {
    137             errorDescription = "No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
    138 
    139             if (isInterestingStatusCode(response.httpStatusCode()))
    140                 errorDescription.append(" The response had HTTP status code " + String::number(response.httpStatusCode()) + ".");
    141         } else if (accessControlOriginString.string().find(isOriginSeparator, 0) != kNotFound) {
    142             errorDescription = "The 'Access-Control-Allow-Origin' header contains multiple values '" + accessControlOriginString + "', but only one is allowed. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
    143         } else {
    144             KURL headerOrigin(KURL(), accessControlOriginString);
    145             if (!headerOrigin.isValid())
    146                 errorDescription = "The 'Access-Control-Allow-Origin' header contains the invalid value '" + accessControlOriginString + "'. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
    147             else
    148                 errorDescription = "The 'Access-Control-Allow-Origin' header has a value '" + accessControlOriginString + "' that is not equal to the supplied origin. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
    149         }
    150         return false;
    151     }
    152 
    153     if (includeCredentials == AllowStoredCredentials) {
    154         const AtomicString& accessControlCredentialsString = response.httpHeaderField(accessControlAllowCredentials);
    155         if (accessControlCredentialsString != "true") {
    156             errorDescription = "Credentials flag is 'true', but the 'Access-Control-Allow-Credentials' header is '" + accessControlCredentialsString + "'. It must be 'true' to allow credentials.";
    157             return false;
    158         }
    159     }
    160 
    161     return true;
    162 }
    163 
    164 bool passesPreflightStatusCheck(const ResourceResponse& response, String& errorDescription)
    165 {
    166     if (response.httpStatusCode() < 200 || response.httpStatusCode() >= 400) {
    167         errorDescription = "Invalid HTTP status code " + String::number(response.httpStatusCode());
    168         return false;
    169     }
    170 
    171     return true;
    172 }
    173 
    174 void parseAccessControlExposeHeadersAllowList(const String& headerValue, HTTPHeaderSet& headerSet)
    175 {
    176     Vector<String> headers;
    177     headerValue.split(',', false, headers);
    178     for (unsigned headerCount = 0; headerCount < headers.size(); headerCount++) {
    179         String strippedHeader = headers[headerCount].stripWhiteSpace();
    180         if (!strippedHeader.isEmpty())
    181             headerSet.add(strippedHeader);
    182     }
    183 }
    184 
    185 bool CrossOriginAccessControl::isLegalRedirectLocation(const KURL& requestURL, String& errorDescription)
    186 {
    187     // CORS restrictions imposed on Location: URL -- http://www.w3.org/TR/cors/#redirect-steps (steps 2 + 3.)
    188     if (!SchemeRegistry::shouldTreatURLSchemeAsCORSEnabled(requestURL.protocol())) {
    189         errorDescription = "The request was redirected to a URL ('" + requestURL.string() + "') which has a disallowed scheme for cross-origin requests.";
    190         return false;
    191     }
    192 
    193     if (!(requestURL.user().isEmpty() && requestURL.pass().isEmpty())) {
    194         errorDescription = "The request was redirected to a URL ('" + requestURL.string() + "') containing userinfo, which is disallowed for cross-origin requests.";
    195         return false;
    196     }
    197 
    198     return true;
    199 }
    200 
    201 bool CrossOriginAccessControl::handleRedirect(Resource* resource, SecurityOrigin* securityOrigin, ResourceRequest& request, const ResourceResponse& redirectResponse, ResourceLoaderOptions& options, String& errorMessage)
    202 {
    203     // http://www.w3.org/TR/cors/#redirect-steps terminology:
    204     const KURL& originalURL = redirectResponse.url();
    205     const KURL& requestURL = request.url();
    206 
    207     bool redirectCrossOrigin = !securityOrigin->canRequest(requestURL);
    208 
    209     // Same-origin request URLs that redirect are allowed without checking access.
    210     if (!securityOrigin->canRequest(originalURL)) {
    211         // Follow http://www.w3.org/TR/cors/#redirect-steps
    212         String errorDescription;
    213 
    214         // Steps 3 & 4 - check if scheme and other URL restrictions hold.
    215         bool allowRedirect = isLegalRedirectLocation(requestURL, errorDescription);
    216         if (allowRedirect) {
    217             // Step 5: perform resource sharing access check.
    218             StoredCredentials withCredentials = resource->lastResourceRequest().allowStoredCredentials() ? AllowStoredCredentials : DoNotAllowStoredCredentials;
    219             allowRedirect = passesAccessControlCheck(redirectResponse, withCredentials, securityOrigin, errorDescription);
    220             if (allowRedirect) {
    221                 RefPtr<SecurityOrigin> originalOrigin = SecurityOrigin::create(originalURL);
    222                 // Step 6: if the request URL origin is not same origin as the original URL's,
    223                 // set the source origin to a globally unique identifier.
    224                 if (!originalOrigin->canRequest(requestURL)) {
    225                     options.securityOrigin = SecurityOrigin::createUnique();
    226                     securityOrigin = options.securityOrigin.get();
    227                 }
    228             }
    229         }
    230         if (!allowRedirect) {
    231             const String& originalOrigin = SecurityOrigin::create(originalURL)->toString();
    232             errorMessage = "Redirect at origin '" + originalOrigin + "' has been blocked from loading by Cross-Origin Resource Sharing policy: " + errorDescription;
    233             return false;
    234         }
    235     }
    236     if (redirectCrossOrigin) {
    237         // If now to a different origin, update/set Origin:.
    238         request.clearHTTPOrigin();
    239         request.setHTTPOrigin(securityOrigin->toAtomicString());
    240         // If the user didn't request credentials in the first place, update our
    241         // state so we neither request them nor expect they must be allowed.
    242         if (options.credentialsRequested == ClientDidNotRequestCredentials)
    243             options.allowCredentials = DoNotAllowStoredCredentials;
    244     }
    245     return true;
    246 }
    247 
    248 } // namespace blink
    249