text: /*
   * Copyright (C) 2011 Google 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:
   *
   *     * Redistributions of source code must retain the above copyright
   * notice, this list of conditions and the following disclaimer.
   *     * 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.
   *     * Neither the name of Google Inc. nor the names of its
   * contributors may be used to endorse or promote products derived from
   * this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "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 THE COPYRIGHT
   * OWNER 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/LinkLoader.h"
  
  #include "core/FetchInitiatorTypeNames.h"
  #include "core/dom/Document.h"
  #include "core/fetch/FetchRequest.h"
  #include "core/fetch/ResourceFetcher.h"
  #include "core/frame/Settings.h"
  #include "core/html/LinkRelAttribute.h"
  #include "core/loader/PrerenderHandle.h"
  #include "platform/Prerender.h"
  #include "platform/network/DNS.h"
  #include "public/platform/WebPrerender.h"
  
  namespace blink {
  
  static unsigned prerenderRelTypesFromRelAttribute(const LinkRelAttribute& relAttribute)
  {
      unsigned result = 0;
      if (relAttribute.isLinkPrerender())
          result |= blink::PrerenderRelTypePrerender;
      if (relAttribute.isLinkNext())
          result |= blink::PrerenderRelTypeNext;
  
      return result;
  }
  
  LinkLoader::LinkLoader(LinkLoaderClient* client)
      : m_client(client)
      , m_linkLoadTimer(this, &LinkLoader::linkLoadTimerFired)
      , m_linkLoadingErrorTimer(this, &LinkLoader::linkLoadingErrorTimerFired)
  {
  }
  
  LinkLoader::~LinkLoader()
  {
  }
  
  void LinkLoader::linkLoadTimerFired(Timer<LinkLoader>* timer)
  {
      ASSERT_UNUSED(timer, timer == &m_linkLoadTimer);
      m_client->linkLoaded();
  }
  
  void LinkLoader::linkLoadingErrorTimerFired(Timer<LinkLoader>* timer)
  {
      ASSERT_UNUSED(timer, timer == &m_linkLoadingErrorTimer);
      m_client->linkLoadingErrored();
  }
  
  void LinkLoader::notifyFinished(Resource* resource)
  {
      ASSERT(this->resource() == resource);
  
      if (resource->errorOccurred())
          m_linkLoadingErrorTimer.startOneShot(0, FROM_HERE);
      else
          m_linkLoadTimer.startOneShot(0, FROM_HERE);
  
      clearResource();
  }
  
  void LinkLoader::didStartPrerender()
  {
      m_client->didStartLinkPrerender();
  }
  
  void LinkLoader::didStopPrerender()
  {
      m_client->didStopLinkPrerender();
  }
  
  void LinkLoader::didSendLoadForPrerender()
  {
      m_client->didSendLoadForLinkPrerender();
  }
  
  void LinkLoader::didSendDOMContentLoadedForPrerender()
  {
      m_client->didSendDOMContentLoadedForLinkPrerender();
  }
  
  bool LinkLoader::loadLink(const LinkRelAttribute& relAttribute, const AtomicString& crossOriginMode, const String& type, const KURL& href, Document& document)
  {
      if (relAttribute.isDNSPrefetch()) {
          Settings* settings = document.settings();
          // FIXME: The href attribute of the link element can be in "//hostname" form, and we shouldn't attempt
          // to complete that as URL <https://bugs.webkit.org/show_bug.cgi?id=48857>.
          if (settings && settings->dnsPrefetchingEnabled() && href.isValid() && !href.isEmpty())
              prefetchDNS(href.host());
      }
  
      // FIXME(crbug.com/323096): Should take care of import.
      if ((relAttribute.isLinkPrefetch() || relAttribute.isLinkSubresource() || relAttribute.isTransitionExitingStylesheet()) && href.isValid() && document.frame()) {
          if (!m_client->shouldLoadLink())
              return false;
          Resource::Type type = relAttribute.isLinkSubresource() ?  Resource::LinkSubresource : Resource::LinkPrefetch;
          FetchRequest linkRequest(ResourceRequest(document.completeURL(href)), FetchInitiatorTypeNames::link);
          if (!crossOriginMode.isNull())
              linkRequest.setCrossOriginAccessControl(document.securityOrigin(), crossOriginMode);
          setResource(document.fetcher()->fetchLinkResource(type, linkRequest));
      }
  
      if (const unsigned prerenderRelTypes = prerenderRelTypesFromRelAttribute(relAttribute)) {
          if (!m_prerender) {
              m_prerender = PrerenderHandle::create(document, this, href, prerenderRelTypes);
          } else if (m_prerender->url() != href) {
              m_prerender->cancel();
              m_prerender = PrerenderHandle::create(document, this, href, prerenderRelTypes);
          }
          // TODO(gavinp): Handle changes to rel types of existing prerenders.
      } else if (m_prerender) {
          m_prerender->cancel();
          m_prerender.clear();
      }
      return true;
  }
  
  void LinkLoader::released()
  {
      // Only prerenders need treatment here; other links either use the Resource interface, or are notionally
      // atomic (dns prefetch).
      if (m_prerender) {
          m_prerender->cancel();
          m_prerender.clear();
      }
  }
  
  void LinkLoader::trace(Visitor* visitor)
  {
      visitor->trace(m_prerender);
  }
  
  }
  