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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 "platform/network/HTTPParsers.h"
     31 #include "platform/network/ResourceResponse.h"
     32 #include "platform/weborigin/SecurityOrigin.h"
     33 #include "wtf/Threading.h"
     34 #include "wtf/text/AtomicString.h"
     35 #include "wtf/text/StringBuilder.h"
     36 
     37 namespace WebCore {
     38 
     39 bool isOnAccessControlSimpleRequestMethodWhitelist(const String& method)
     40 {
     41     return method == "GET" || method == "HEAD" || method == "POST";
     42 }
     43 
     44 bool isOnAccessControlSimpleRequestHeaderWhitelist(const AtomicString& name, const AtomicString& value)
     45 {
     46     if (equalIgnoringCase(name, "accept")
     47         || equalIgnoringCase(name, "accept-language")
     48         || equalIgnoringCase(name, "content-language")
     49         || equalIgnoringCase(name, "origin")
     50         || equalIgnoringCase(name, "referer"))
     51         return true;
     52 
     53     // Preflight is required for MIME types that can not be sent via form submission.
     54     if (equalIgnoringCase(name, "content-type")) {
     55         AtomicString mimeType = extractMIMETypeFromMediaType(value);
     56         return equalIgnoringCase(mimeType, "application/x-www-form-urlencoded")
     57             || equalIgnoringCase(mimeType, "multipart/form-data")
     58             || equalIgnoringCase(mimeType, "text/plain");
     59     }
     60 
     61     return false;
     62 }
     63 
     64 bool isSimpleCrossOriginAccessRequest(const String& method, const HTTPHeaderMap& headerMap)
     65 {
     66     if (!isOnAccessControlSimpleRequestMethodWhitelist(method))
     67         return false;
     68 
     69     HTTPHeaderMap::const_iterator end = headerMap.end();
     70     for (HTTPHeaderMap::const_iterator it = headerMap.begin(); it != end; ++it) {
     71         if (!isOnAccessControlSimpleRequestHeaderWhitelist(it->key, it->value))
     72             return false;
     73     }
     74 
     75     return true;
     76 }
     77 
     78 static PassOwnPtr<HTTPHeaderSet> createAllowedCrossOriginResponseHeadersSet()
     79 {
     80     OwnPtr<HTTPHeaderSet> headerSet = adoptPtr(new HashSet<String, CaseFoldingHash>);
     81 
     82     headerSet->add("cache-control");
     83     headerSet->add("content-language");
     84     headerSet->add("content-type");
     85     headerSet->add("expires");
     86     headerSet->add("last-modified");
     87     headerSet->add("pragma");
     88 
     89     return headerSet.release();
     90 }
     91 
     92 bool isOnAccessControlResponseHeaderWhitelist(const String& name)
     93 {
     94     AtomicallyInitializedStatic(HTTPHeaderSet*, allowedCrossOriginResponseHeaders = createAllowedCrossOriginResponseHeadersSet().leakPtr());
     95 
     96     return allowedCrossOriginResponseHeaders->contains(name);
     97 }
     98 
     99 void updateRequestForAccessControl(ResourceRequest& request, SecurityOrigin* securityOrigin, StoredCredentials allowCredentials)
    100 {
    101     request.removeCredentials();
    102     request.setAllowCookies(allowCredentials == AllowStoredCredentials);
    103 
    104     if (securityOrigin)
    105         request.setHTTPOrigin(securityOrigin->toString());
    106 }
    107 
    108 ResourceRequest createAccessControlPreflightRequest(const ResourceRequest& request, SecurityOrigin* securityOrigin)
    109 {
    110     ResourceRequest preflightRequest(request.url());
    111     updateRequestForAccessControl(preflightRequest, securityOrigin, DoNotAllowStoredCredentials);
    112     preflightRequest.setHTTPMethod("OPTIONS");
    113     preflightRequest.setHTTPHeaderField("Access-Control-Request-Method", request.httpMethod());
    114     preflightRequest.setPriority(request.priority());
    115 
    116     const HTTPHeaderMap& requestHeaderFields = request.httpHeaderFields();
    117 
    118     if (requestHeaderFields.size() > 0) {
    119         StringBuilder headerBuffer;
    120         HTTPHeaderMap::const_iterator it = requestHeaderFields.begin();
    121         headerBuffer.append(it->key);
    122         ++it;
    123 
    124         HTTPHeaderMap::const_iterator end = requestHeaderFields.end();
    125         for (; it != end; ++it) {
    126             headerBuffer.appendLiteral(", ");
    127             headerBuffer.append(it->key);
    128         }
    129 
    130         preflightRequest.setHTTPHeaderField("Access-Control-Request-Headers", headerBuffer.toString().lower());
    131     }
    132 
    133     return preflightRequest;
    134 }
    135 
    136 static bool isOriginSeparator(UChar ch)
    137 {
    138     return isASCIISpace(ch) || ch == ',';
    139 }
    140 
    141 bool passesAccessControlCheck(const ResourceResponse& response, StoredCredentials includeCredentials, SecurityOrigin* securityOrigin, String& errorDescription)
    142 {
    143     AtomicallyInitializedStatic(AtomicString&, accessControlAllowOrigin = *new AtomicString("access-control-allow-origin", AtomicString::ConstructFromLiteral));
    144     AtomicallyInitializedStatic(AtomicString&, accessControlAllowCredentials = *new AtomicString("access-control-allow-credentials", AtomicString::ConstructFromLiteral));
    145 
    146     // A wildcard Access-Control-Allow-Origin can not be used if credentials are to be sent,
    147     // even with Access-Control-Allow-Credentials set to true.
    148     const AtomicString& accessControlOriginString = response.httpHeaderField(accessControlAllowOrigin);
    149     if (accessControlOriginString == starAtom && includeCredentials == DoNotAllowStoredCredentials)
    150         return true;
    151 
    152     if (accessControlOriginString != securityOrigin->toString()) {
    153         if (accessControlOriginString == starAtom) {
    154             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.";
    155         } else if (accessControlOriginString.isEmpty()) {
    156             errorDescription = "No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
    157         } else if (accessControlOriginString.string().find(isOriginSeparator, 0) != kNotFound) {
    158             errorDescription = "The 'Access-Control-Allow-Origin' header contains multiple values '" + accessControlOriginString + "', but only one is allowed. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
    159         } else {
    160             KURL headerOrigin(KURL(), accessControlOriginString);
    161             if (!headerOrigin.isValid())
    162                 errorDescription = "The 'Access-Control-Allow-Origin' header contains the invalid value '" + accessControlOriginString + "'. Origin '" + securityOrigin->toString() + "' is therefore not allowed access.";
    163             else
    164                 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.";
    165         }
    166         return false;
    167     }
    168 
    169     if (includeCredentials == AllowStoredCredentials) {
    170         const AtomicString& accessControlCredentialsString = response.httpHeaderField(accessControlAllowCredentials);
    171         if (accessControlCredentialsString != "true") {
    172             errorDescription = "Credentials flag is 'true', but the 'Access-Control-Allow-Credentials' header is '" + accessControlCredentialsString + "'. It must be 'true' to allow credentials.";
    173             return false;
    174         }
    175     }
    176 
    177     return true;
    178 }
    179 
    180 bool passesPreflightStatusCheck(const ResourceResponse& response, String& errorDescription)
    181 {
    182     if (response.httpStatusCode() < 200 || response.httpStatusCode() >= 400) {
    183         errorDescription = "Invalid HTTP status code " + String::number(response.httpStatusCode());
    184         return false;
    185     }
    186 
    187     return true;
    188 }
    189 
    190 void parseAccessControlExposeHeadersAllowList(const String& headerValue, HTTPHeaderSet& headerSet)
    191 {
    192     Vector<String> headers;
    193     headerValue.split(',', false, headers);
    194     for (unsigned headerCount = 0; headerCount < headers.size(); headerCount++) {
    195         String strippedHeader = headers[headerCount].stripWhiteSpace();
    196         if (!strippedHeader.isEmpty())
    197             headerSet.add(strippedHeader);
    198     }
    199 }
    200 
    201 } // namespace WebCore
    202