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      1 /*
      2  * Copyright (C) 2008, 2009 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 "CrossOriginPreflightResultCache.h"
     29 
     30 #include "CrossOriginAccessControl.h"
     31 #include "ResourceResponse.h"
     32 #include <wtf/CurrentTime.h>
     33 #include <wtf/StdLibExtras.h>
     34 #include <wtf/Threading.h>
     35 
     36 namespace WebCore {
     37 
     38 using namespace std;
     39 
     40 // These values are at the discretion of the user agent.
     41 static const unsigned defaultPreflightCacheTimeoutSeconds = 5;
     42 static const unsigned maxPreflightCacheTimeoutSeconds = 600; // Should be short enough to minimize the risk of using a poisoned cache after switching to a secure network.
     43 
     44 static bool parseAccessControlMaxAge(const String& string, unsigned& expiryDelta)
     45 {
     46     // FIXME: this will not do the correct thing for a number starting with a '+'
     47     bool ok = false;
     48     expiryDelta = string.toUIntStrict(&ok);
     49     return ok;
     50 }
     51 
     52 template<class HashType>
     53 static void addToAccessControlAllowList(const String& string, unsigned start, unsigned end, HashSet<String, HashType>& set)
     54 {
     55     StringImpl* stringImpl = string.impl();
     56     if (!stringImpl)
     57         return;
     58 
     59     // Skip white space from start.
     60     while (start <= end && isSpaceOrNewline((*stringImpl)[start]))
     61         ++start;
     62 
     63     // only white space
     64     if (start > end)
     65         return;
     66 
     67     // Skip white space from end.
     68     while (end && isSpaceOrNewline((*stringImpl)[end]))
     69         --end;
     70 
     71     set.add(string.substring(start, end - start + 1));
     72 }
     73 
     74 template<class HashType>
     75 static bool parseAccessControlAllowList(const String& string, HashSet<String, HashType>& set)
     76 {
     77     unsigned start = 0;
     78     size_t end;
     79     while ((end = string.find(',', start)) != notFound) {
     80         if (start == end)
     81             return false;
     82 
     83         addToAccessControlAllowList(string, start, end - 1, set);
     84         start = end + 1;
     85     }
     86     if (start != string.length())
     87         addToAccessControlAllowList(string, start, string.length() - 1, set);
     88 
     89     return true;
     90 }
     91 
     92 bool CrossOriginPreflightResultCacheItem::parse(const ResourceResponse& response, String& errorDescription)
     93 {
     94     m_methods.clear();
     95     if (!parseAccessControlAllowList(response.httpHeaderField("Access-Control-Allow-Methods"), m_methods)) {
     96         errorDescription = "Cannot parse Access-Control-Allow-Methods response header field.";
     97         return false;
     98     }
     99 
    100     m_headers.clear();
    101     if (!parseAccessControlAllowList(response.httpHeaderField("Access-Control-Allow-Headers"), m_headers)) {
    102         errorDescription = "Cannot parse Access-Control-Allow-Headers response header field.";
    103         return false;
    104     }
    105 
    106     unsigned expiryDelta;
    107     if (parseAccessControlMaxAge(response.httpHeaderField("Access-Control-Max-Age"), expiryDelta)) {
    108         if (expiryDelta > maxPreflightCacheTimeoutSeconds)
    109             expiryDelta = maxPreflightCacheTimeoutSeconds;
    110     } else
    111         expiryDelta = defaultPreflightCacheTimeoutSeconds;
    112 
    113     m_absoluteExpiryTime = currentTime() + expiryDelta;
    114     return true;
    115 }
    116 
    117 bool CrossOriginPreflightResultCacheItem::allowsCrossOriginMethod(const String& method, String& errorDescription) const
    118 {
    119     if (m_methods.contains(method) || isOnAccessControlSimpleRequestMethodWhitelist(method))
    120         return true;
    121 
    122     errorDescription = "Method " + method + " is not allowed by Access-Control-Allow-Methods.";
    123     return false;
    124 }
    125 
    126 bool CrossOriginPreflightResultCacheItem::allowsCrossOriginHeaders(const HTTPHeaderMap& requestHeaders, String& errorDescription) const
    127 {
    128     HTTPHeaderMap::const_iterator end = requestHeaders.end();
    129     for (HTTPHeaderMap::const_iterator it = requestHeaders.begin(); it != end; ++it) {
    130         if (!m_headers.contains(it->first) && !isOnAccessControlSimpleRequestHeaderWhitelist(it->first, it->second)) {
    131             errorDescription = "Request header field " + it->first.string() + " is not allowed by Access-Control-Allow-Headers.";
    132             return false;
    133         }
    134     }
    135     return true;
    136 }
    137 
    138 bool CrossOriginPreflightResultCacheItem::allowsRequest(bool includeCredentials, const String& method, const HTTPHeaderMap& requestHeaders) const
    139 {
    140     String ignoredExplanation;
    141     if (m_absoluteExpiryTime < currentTime())
    142         return false;
    143     if (includeCredentials && !m_credentials)
    144         return false;
    145     if (!allowsCrossOriginMethod(method, ignoredExplanation))
    146         return false;
    147     if (!allowsCrossOriginHeaders(requestHeaders, ignoredExplanation))
    148         return false;
    149     return true;
    150 }
    151 
    152 CrossOriginPreflightResultCache& CrossOriginPreflightResultCache::shared()
    153 {
    154     DEFINE_STATIC_LOCAL(CrossOriginPreflightResultCache, cache, ());
    155     ASSERT(isMainThread());
    156     return cache;
    157 }
    158 
    159 void CrossOriginPreflightResultCache::appendEntry(const String& origin, const KURL& url, PassOwnPtr<CrossOriginPreflightResultCacheItem> preflightResult)
    160 {
    161     ASSERT(isMainThread());
    162     CrossOriginPreflightResultCacheItem* resultPtr = preflightResult.leakPtr();
    163     pair<CrossOriginPreflightResultHashMap::iterator, bool> addResult = m_preflightHashMap.add(make_pair(origin, url), resultPtr);
    164     if (!addResult.second) {
    165         // FIXME: We need to delete the old value before replacing with the new one.
    166         addResult.first->second = resultPtr;
    167     }
    168 }
    169 
    170 bool CrossOriginPreflightResultCache::canSkipPreflight(const String& origin, const KURL& url, bool includeCredentials, const String& method, const HTTPHeaderMap& requestHeaders)
    171 {
    172     ASSERT(isMainThread());
    173     CrossOriginPreflightResultHashMap::iterator cacheIt = m_preflightHashMap.find(std::make_pair(origin, url));
    174     if (cacheIt == m_preflightHashMap.end())
    175         return false;
    176 
    177     if (cacheIt->second->allowsRequest(includeCredentials, method, requestHeaders))
    178         return true;
    179 
    180     delete cacheIt->second;
    181     m_preflightHashMap.remove(cacheIt);
    182     return false;
    183 }
    184 
    185 void CrossOriginPreflightResultCache::empty()
    186 {
    187     ASSERT(isMainThread());
    188     deleteAllValues(m_preflightHashMap);
    189     m_preflightHashMap.clear();
    190 }
    191 
    192 } // namespace WebCore
    193