text: /*
   * Copyright (C) 2008, 2009 Apple Inc. All Rights Reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
   * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
   * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   */
  
  #include "config.h"
  #include "core/loader/CrossOriginPreflightResultCache.h"
  
  #include "core/fetch/FetchUtils.h"
  #include "platform/network/ResourceResponse.h"
  #include "wtf/CurrentTime.h"
  #include "wtf/MainThread.h"
  #include "wtf/StdLibExtras.h"
  
  namespace blink {
  
  // These values are at the discretion of the user agent.
  static const unsigned defaultPreflightCacheTimeoutSeconds = 5;
  static const unsigned maxPreflightCacheTimeoutSeconds = 600; // Should be short enough to minimize the risk of using a poisoned cache after switching to a secure network.
  
  static bool parseAccessControlMaxAge(const String& string, unsigned& expiryDelta)
  {
      // FIXME: this will not do the correct thing for a number starting with a '+'
      bool ok = false;
      expiryDelta = string.toUIntStrict(&ok);
      return ok;
  }
  
  template<class HashType>
  static void addToAccessControlAllowList(const String& string, unsigned start, unsigned end, HashSet<String, HashType>& set)
  {
      StringImpl* stringImpl = string.impl();
      if (!stringImpl)
          return;
  
      // Skip white space from start.
      while (start <= end && isSpaceOrNewline((*stringImpl)[start]))
          ++start;
  
      // only white space
      if (start > end)
          return;
  
      // Skip white space from end.
      while (end && isSpaceOrNewline((*stringImpl)[end]))
          --end;
  
      set.add(string.substring(start, end - start + 1));
  }
  
  template<class HashType>
  static bool parseAccessControlAllowList(const String& string, HashSet<String, HashType>& set)
  {
      unsigned start = 0;
      size_t end;
      while ((end = string.find(',', start)) != kNotFound) {
          if (start != end)
              addToAccessControlAllowList(string, start, end - 1, set);
          start = end + 1;
      }
      if (start != string.length())
          addToAccessControlAllowList(string, start, string.length() - 1, set);
  
      return true;
  }
  
  bool CrossOriginPreflightResultCacheItem::parse(const ResourceResponse& response, String& errorDescription)
  {
      m_methods.clear();
      if (!parseAccessControlAllowList(response.httpHeaderField("Access-Control-Allow-Methods"), m_methods)) {
          errorDescription = "Cannot parse Access-Control-Allow-Methods response header field.";
          return false;
      }
  
      m_headers.clear();
      if (!parseAccessControlAllowList(response.httpHeaderField("Access-Control-Allow-Headers"), m_headers)) {
          errorDescription = "Cannot parse Access-Control-Allow-Headers response header field.";
          return false;
      }
  
      unsigned expiryDelta;
      if (parseAccessControlMaxAge(response.httpHeaderField("Access-Control-Max-Age"), expiryDelta)) {
          if (expiryDelta > maxPreflightCacheTimeoutSeconds)
              expiryDelta = maxPreflightCacheTimeoutSeconds;
      } else {
          expiryDelta = defaultPreflightCacheTimeoutSeconds;
      }
  
      m_absoluteExpiryTime = currentTime() + expiryDelta;
      return true;
  }
  
  bool CrossOriginPreflightResultCacheItem::allowsCrossOriginMethod(const String& method, String& errorDescription) const
  {
      if (m_methods.contains(method) || FetchUtils::isSimpleMethod(method))
          return true;
  
      errorDescription = "Method " + method + " is not allowed by Access-Control-Allow-Methods.";
      return false;
  }
  
  bool CrossOriginPreflightResultCacheItem::allowsCrossOriginHeaders(const HTTPHeaderMap& requestHeaders, String& errorDescription) const
  {
      HTTPHeaderMap::const_iterator end = requestHeaders.end();
      for (HTTPHeaderMap::const_iterator it = requestHeaders.begin(); it != end; ++it) {
          if (!m_headers.contains(it->key) && !FetchUtils::isSimpleHeader(it->key, it->value) && !FetchUtils::isForbiddenHeaderName(it->key)) {
              errorDescription = "Request header field " + it->key.string() + " is not allowed by Access-Control-Allow-Headers.";
              return false;
          }
      }
      return true;
  }
  
  bool CrossOriginPreflightResultCacheItem::allowsRequest(StoredCredentials includeCredentials, const String& method, const HTTPHeaderMap& requestHeaders) const
  {
      String ignoredExplanation;
      if (m_absoluteExpiryTime < currentTime())
          return false;
      if (includeCredentials == AllowStoredCredentials && m_credentials == DoNotAllowStoredCredentials)
          return false;
      if (!allowsCrossOriginMethod(method, ignoredExplanation))
          return false;
      if (!allowsCrossOriginHeaders(requestHeaders, ignoredExplanation))
          return false;
      return true;
  }
  
  CrossOriginPreflightResultCache& CrossOriginPreflightResultCache::shared()
  {
      DEFINE_STATIC_LOCAL(CrossOriginPreflightResultCache, cache, ());
      ASSERT(isMainThread());
      return cache;
  }
  
  void CrossOriginPreflightResultCache::appendEntry(const String& origin, const KURL& url, PassOwnPtr<CrossOriginPreflightResultCacheItem> preflightResult)
  {
      ASSERT(isMainThread());
      m_preflightHashMap.set(std::make_pair(origin, url), preflightResult);
  }
  
  bool CrossOriginPreflightResultCache::canSkipPreflight(const String& origin, const KURL& url, StoredCredentials includeCredentials, const String& method, const HTTPHeaderMap& requestHeaders)
  {
      ASSERT(isMainThread());
      CrossOriginPreflightResultHashMap::iterator cacheIt = m_preflightHashMap.find(std::make_pair(origin, url));
      if (cacheIt == m_preflightHashMap.end())
          return false;
  
      if (cacheIt->value->allowsRequest(includeCredentials, method, requestHeaders))
          return true;
  
      m_preflightHashMap.remove(cacheIt);
      return false;
  }
  
  } // namespace blink
  