Source/WebCore/loader/PolicyChecker.cpp - WebKit - Git at Google

 /*
  * Copyright (C) 2006-2018 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * 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.
  * 3.  Neither the name of Apple Inc. ("Apple") 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 APPLE AND ITS 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 APPLE OR ITS 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 "PolicyChecker.h"

 #include "BlobRegistry.h"
 #include "BlobURL.h"
 #include "ContentFilter.h"
 #include "ContentSecurityPolicy.h"
 #include "DOMWindow.h"
 #include "DocumentLoader.h"
 #include "Event.h"
 #include "EventNames.h"
 #include "FormState.h"
 #include "Frame.h"
 #include "FrameLoader.h"
 #include "FrameLoaderClient.h"
 #include "HTMLFormElement.h"
 #include "HTMLFrameOwnerElement.h"
 #include "HTMLPlugInElement.h"
 #include "Logging.h"
 #include <wtf/CompletionHandler.h>

 #if USE(QUICK_LOOK)
 #include "QuickLook.h"
 #endif

 #define IS_ALLOWED (m_frame.page() ? m_frame.page()->sessionID().isAlwaysOnLoggingAllowed() : false)
 #define PAGE_ID (m_frame.loader().client().pageID().valueOr(PageIdentifier()).toUInt64())
 #define FRAME_ID (m_frame.loader().client().frameID().valueOr(FrameIdentifier()).toUInt64())
 #define RELEASE_LOG_IF_ALLOWED(fmt, ...) RELEASE_LOG_IF(IS_ALLOWED, Loading, "%p - [pageID=%" PRIu64 ", frameID=%" PRIu64 "] PolicyChecker::" fmt, this, PAGE_ID, FRAME_ID, ##__VA_ARGS__)

 namespace WebCore {

 static bool isAllowedByContentSecurityPolicy(const URL& url, const Element* ownerElement, bool didReceiveRedirectResponse)
 {
     if (!ownerElement)
         return true;
     // Elements in user agent show tree should load whatever the embedding document policy is.
     if (ownerElement->isInUserAgentShadowTree())
         return true;

     auto redirectResponseReceived = didReceiveRedirectResponse ? ContentSecurityPolicy::RedirectResponseReceived::Yes : ContentSecurityPolicy::RedirectResponseReceived::No;

     ASSERT(ownerElement->document().contentSecurityPolicy());
     if (is<HTMLPlugInElement>(ownerElement))
         return ownerElement->document().contentSecurityPolicy()->allowObjectFromSource(url, redirectResponseReceived);
     return ownerElement->document().contentSecurityPolicy()->allowChildFrameFromSource(url, redirectResponseReceived);
 }

 PolicyCheckIdentifier PolicyCheckIdentifier::create()
 {
     static uint64_t identifier = 0;
     identifier++;
     return PolicyCheckIdentifier { Process::identifier(), identifier };
 }

 bool PolicyCheckIdentifier::isValidFor(PolicyCheckIdentifier expectedIdentifier)
 {
     RELEASE_ASSERT_WITH_MESSAGE(m_policyCheck, "Received 0 as the policy check identifier");
     RELEASE_ASSERT_WITH_MESSAGE(m_process == expectedIdentifier.m_process, "Received a policy check response for a wrong process");
     RELEASE_ASSERT_WITH_MESSAGE(m_policyCheck <= expectedIdentifier.m_policyCheck, "Received a policy check response from the future");
     return m_policyCheck == expectedIdentifier.m_policyCheck;
 }

 PolicyChecker::PolicyChecker(Frame& frame)
     : m_frame(frame)
     , m_delegateIsDecidingNavigationPolicy(false)
     , m_delegateIsHandlingUnimplementablePolicy(false)
     , m_loadType(FrameLoadType::Standard)
 {
 }

 void PolicyChecker::checkNavigationPolicy(ResourceRequest&& newRequest, const ResourceResponse& redirectResponse, NavigationPolicyDecisionFunction&& function)
 {
     checkNavigationPolicy(WTFMove(newRequest), redirectResponse, m_frame.loader().activeDocumentLoader(), { }, WTFMove(function));
 }

 CompletionHandlerCallingScope PolicyChecker::extendBlobURLLifetimeIfNecessary(ResourceRequest& request) const
 {
     if (!request.url().protocolIsBlob())
         return { };

     // Create a new temporary blobURL in case this one gets revoked during the asynchronous navigation policy decision.
     URL temporaryBlobURL = BlobURL::createPublicURL(&m_frame.document()->securityOrigin());
     blobRegistry().registerBlobURL(temporaryBlobURL, request.url());
     request.setURL(temporaryBlobURL);
     return CompletionHandler<void()>([temporaryBlobURL = WTFMove(temporaryBlobURL)] {
         blobRegistry().unregisterBlobURL(temporaryBlobURL);
     });
 }

 void PolicyChecker::checkNavigationPolicy(ResourceRequest&& request, const ResourceResponse& redirectResponse, DocumentLoader* loader, RefPtr<FormState>&& formState, NavigationPolicyDecisionFunction&& function, PolicyDecisionMode policyDecisionMode)
 {
     NavigationAction action = loader->triggeringAction();
     if (action.isEmpty()) {
         action = NavigationAction { *m_frame.document(), request, InitiatedByMainFrame::Unknown, NavigationType::Other, loader->shouldOpenExternalURLsPolicyToPropagate() };
         loader->setTriggeringAction(NavigationAction { action });
     }

     if (m_frame.page() && m_frame.page()->openedByDOMWithOpener())
         action.setOpenedByDOMWithOpener();
     action.setHasOpenedFrames(m_frame.loader().hasOpenedFrames());

     // Don't ask more than once for the same request or if we are loading an empty URL.
     // This avoids confusion on the part of the client.
     if (equalIgnoringHeaderFields(request, loader->lastCheckedRequest()) || (!request.isNull() && request.url().isEmpty())) {
         if (!request.isNull() && request.url().isEmpty())
             RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because the URL is empty");
         else
             RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because the URL is the same as the last request");
         function(ResourceRequest(request), { }, NavigationPolicyDecision::ContinueLoad);
         loader->setLastCheckedRequest(WTFMove(request));
         return;
     }

     // We are always willing to show alternate content for unreachable URLs;
     // treat it like a reload so it maintains the right state for b/f list.
     auto& substituteData = loader->substituteData();
     if (substituteData.isValid() && !substituteData.failingURL().isEmpty()) {
         bool shouldContinue = true;
 #if ENABLE(CONTENT_FILTERING)
         shouldContinue = ContentFilter::continueAfterSubstituteDataRequest(*m_frame.loader().activeDocumentLoader(), substituteData);
 #endif
         if (isBackForwardLoadType(m_loadType))
             m_loadType = FrameLoadType::Reload;
         if (shouldContinue)
             RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because we have valid substitute data");
         else
             RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: not continuing with substitute data because the content filter told us not to");

         function(WTFMove(request), { }, shouldContinue ? NavigationPolicyDecision::ContinueLoad : NavigationPolicyDecision::IgnoreLoad);
         return;
     }

     if (!isAllowedByContentSecurityPolicy(request.url(), m_frame.ownerElement(), !redirectResponse.isNull())) {
         if (m_frame.ownerElement()) {
             // Fire a load event (even though we were blocked by CSP) as timing attacks would otherwise
             // reveal that the frame was blocked. This way, it looks like any other cross-origin page load.
             m_frame.ownerElement()->dispatchEvent(Event::create(eventNames().loadEvent, Event::CanBubble::No, Event::IsCancelable::No));
         }
         RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: ignoring because disallowed by content security policy");
         function(WTFMove(request), { }, NavigationPolicyDecision::IgnoreLoad);
         return;
     }

     loader->setLastCheckedRequest(ResourceRequest(request));

 #if USE(QUICK_LOOK)
     // Always allow QuickLook-generated URLs based on the protocol scheme.
     if (!request.isNull() && isQuickLookPreviewURL(request.url())) {
         RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because quicklook-generated URL");
         return function(WTFMove(request), makeWeakPtr(formState.get()), NavigationPolicyDecision::ContinueLoad);
     }
 #endif

 #if ENABLE(CONTENT_FILTERING)
     if (m_contentFilterUnblockHandler.canHandleRequest(request)) {
         RefPtr<Frame> frame { &m_frame };
         m_contentFilterUnblockHandler.requestUnblockAsync([frame](bool unblocked) {
             if (unblocked)
                 frame->loader().reload();
         });
         RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: ignoring because ContentFilterUnblockHandler can handle the request");
         return function({ }, nullptr, NavigationPolicyDecision::IgnoreLoad);
     }
     m_contentFilterUnblockHandler = { };
 #endif

     m_frame.loader().clearProvisionalLoadForPolicyCheck();

     auto blobURLLifetimeExtension = policyDecisionMode == PolicyDecisionMode::Asynchronous ? extendBlobURLLifetimeIfNecessary(request) : CompletionHandlerCallingScope { };

     bool isInitialEmptyDocumentLoad = !m_frame.loader().stateMachine().committedFirstRealDocumentLoad() && request.url().protocolIsAbout() && !substituteData.isValid();
     auto requestIdentifier = PolicyCheckIdentifier::create();
     m_delegateIsDecidingNavigationPolicy = true;
     String suggestedFilename = action.downloadAttribute().isEmpty() ? nullAtom() : action.downloadAttribute();
     FramePolicyFunction decisionHandler = [this, function = WTFMove(function), request = ResourceRequest(request), formState = WTFMove(formState), suggestedFilename = WTFMove(suggestedFilename),
          blobURLLifetimeExtension = WTFMove(blobURLLifetimeExtension), requestIdentifier, isInitialEmptyDocumentLoad] (PolicyAction policyAction, PolicyCheckIdentifier responseIdentifier) mutable {
         if (!responseIdentifier.isValidFor(requestIdentifier)) {
             RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: ignoring because response is not valid for request");
             return function({ }, nullptr, NavigationPolicyDecision::IgnoreLoad);
         }

         m_delegateIsDecidingNavigationPolicy = false;

         switch (policyAction) {
         case PolicyAction::Download:
             m_frame.loader().setOriginalURLForDownloadRequest(request);
             m_frame.loader().client().startDownload(request, suggestedFilename);
             FALLTHROUGH;
         case PolicyAction::Ignore:
             RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: ignoring because policyAction from dispatchDecidePolicyForNavigationAction is Ignore");
             return function({ }, nullptr, NavigationPolicyDecision::IgnoreLoad);
         case PolicyAction::StopAllLoads:
             RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: stopping because policyAction from dispatchDecidePolicyForNavigationAction is StopAllLoads");
             function({ }, nullptr, NavigationPolicyDecision::StopAllLoads);
             return;
         case PolicyAction::Use:
             if (!m_frame.loader().client().canHandleRequest(request)) {
                 handleUnimplementablePolicy(m_frame.loader().client().cannotShowURLError(request));
                 RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: ignoring because frame loader client can't handle the request");
                 return function({ }, { }, NavigationPolicyDecision::IgnoreLoad);
             }
             if (isInitialEmptyDocumentLoad)
                 RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because this is an initial empty document");
             else
                 RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because this policyAction from dispatchDecidePolicyForNavigationAction is Use");
             return function(WTFMove(request), makeWeakPtr(formState.get()), NavigationPolicyDecision::ContinueLoad);
         }
         ASSERT_NOT_REACHED();
     };

     if (isInitialEmptyDocumentLoad) {
         // We ignore the response from the client for initial empty document loads and proceed with the load synchronously.
         m_frame.loader().client().dispatchDecidePolicyForNavigationAction(action, request, redirectResponse, formState.get(), policyDecisionMode, requestIdentifier, [](PolicyAction, PolicyCheckIdentifier) { });
         decisionHandler(PolicyAction::Use, requestIdentifier);
     } else
         m_frame.loader().client().dispatchDecidePolicyForNavigationAction(action, request, redirectResponse, formState.get(), policyDecisionMode, requestIdentifier, WTFMove(decisionHandler));
 }

 void PolicyChecker::checkNewWindowPolicy(NavigationAction&& navigationAction, ResourceRequest&& request, RefPtr<FormState>&& formState, const String& frameName, NewWindowPolicyDecisionFunction&& function)
 {
     if (m_frame.document() && m_frame.document()->isSandboxed(SandboxPopups))
         return function({ }, nullptr, { }, { }, ShouldContinue::No);

     if (!DOMWindow::allowPopUp(m_frame))
         return function({ }, nullptr, { }, { }, ShouldContinue::No);

     auto blobURLLifetimeExtension = extendBlobURLLifetimeIfNecessary(request);

     auto requestIdentifier = PolicyCheckIdentifier::create();
     m_frame.loader().client().dispatchDecidePolicyForNewWindowAction(navigationAction, request, formState.get(), frameName, requestIdentifier, [frame = makeRef(m_frame), request,
         formState = WTFMove(formState), frameName, navigationAction, function = WTFMove(function), blobURLLifetimeExtension = WTFMove(blobURLLifetimeExtension),
         requestIdentifier] (PolicyAction policyAction, PolicyCheckIdentifier responseIdentifier) mutable {

         if (!responseIdentifier.isValidFor(requestIdentifier))
             return function({ }, nullptr, { }, { }, ShouldContinue::No);

         switch (policyAction) {
         case PolicyAction::Download:
             frame->loader().client().startDownload(request);
             FALLTHROUGH;
         case PolicyAction::Ignore:
             function({ }, nullptr, { }, { }, ShouldContinue::No);
             return;
         case PolicyAction::StopAllLoads:
             ASSERT_NOT_REACHED();
             function({ }, nullptr, { }, { }, ShouldContinue::No);
             return;
         case PolicyAction::Use:
             function(request, makeWeakPtr(formState.get()), frameName, navigationAction, ShouldContinue::Yes);
             return;
         }
         ASSERT_NOT_REACHED();
     });
 }

 void PolicyChecker::stopCheck()
 {
     m_frame.loader().client().cancelPolicyCheck();
 }

 void PolicyChecker::cannotShowMIMEType(const ResourceResponse& response)
 {
     handleUnimplementablePolicy(m_frame.loader().client().cannotShowMIMETypeError(response));
 }

 void PolicyChecker::handleUnimplementablePolicy(const ResourceError& error)
 {
     m_delegateIsHandlingUnimplementablePolicy = true;
     m_frame.loader().client().dispatchUnableToImplementPolicy(error);
     m_delegateIsHandlingUnimplementablePolicy = false;
 }

 } // namespace WebCore

 #undef IS_ALLOWED
 #undef PAGE_ID
 #undef FRAME_ID
 #undef RELEASE_LOG_IF_ALLOWED
	/*
	* Copyright (C) 2006-2018 Apple Inc. All rights reserved.
	* Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
	* Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
	*
	* 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.
	* 3. Neither the name of Apple Inc. ("Apple") 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 APPLE AND ITS 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 APPLE OR ITS 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 "PolicyChecker.h"

	#include "BlobRegistry.h"
	#include "BlobURL.h"
	#include "ContentFilter.h"
	#include "ContentSecurityPolicy.h"
	#include "DOMWindow.h"
	#include "DocumentLoader.h"
	#include "Event.h"
	#include "EventNames.h"
	#include "FormState.h"
	#include "Frame.h"
	#include "FrameLoader.h"
	#include "FrameLoaderClient.h"
	#include "HTMLFormElement.h"
	#include "HTMLFrameOwnerElement.h"
	#include "HTMLPlugInElement.h"
	#include "Logging.h"
	#include <wtf/CompletionHandler.h>

	#if USE(QUICK_LOOK)
	#include "QuickLook.h"
	#endif

	#define IS_ALLOWED (m_frame.page() ? m_frame.page()->sessionID().isAlwaysOnLoggingAllowed() : false)
	#define PAGE_ID (m_frame.loader().client().pageID().valueOr(PageIdentifier()).toUInt64())
	#define FRAME_ID (m_frame.loader().client().frameID().valueOr(FrameIdentifier()).toUInt64())
	#define RELEASE_LOG_IF_ALLOWED(fmt, ...) RELEASE_LOG_IF(IS_ALLOWED, Loading, "%p - [pageID=%" PRIu64 ", frameID=%" PRIu64 "] PolicyChecker::" fmt, this, PAGE_ID, FRAME_ID, ##__VA_ARGS__)

	namespace WebCore {

	static bool isAllowedByContentSecurityPolicy(const URL& url, const Element* ownerElement, bool didReceiveRedirectResponse)
	{
	if (!ownerElement)
	return true;
	// Elements in user agent show tree should load whatever the embedding document policy is.
	if (ownerElement->isInUserAgentShadowTree())
	return true;

	auto redirectResponseReceived = didReceiveRedirectResponse ? ContentSecurityPolicy::RedirectResponseReceived::Yes : ContentSecurityPolicy::RedirectResponseReceived::No;

	ASSERT(ownerElement->document().contentSecurityPolicy());
	if (is<HTMLPlugInElement>(ownerElement))
	return ownerElement->document().contentSecurityPolicy()->allowObjectFromSource(url, redirectResponseReceived);
	return ownerElement->document().contentSecurityPolicy()->allowChildFrameFromSource(url, redirectResponseReceived);
	}

	PolicyCheckIdentifier PolicyCheckIdentifier::create()
	{
	static uint64_t identifier = 0;
	identifier++;
	return PolicyCheckIdentifier { Process::identifier(), identifier };
	}

	bool PolicyCheckIdentifier::isValidFor(PolicyCheckIdentifier expectedIdentifier)
	{
	RELEASE_ASSERT_WITH_MESSAGE(m_policyCheck, "Received 0 as the policy check identifier");
	RELEASE_ASSERT_WITH_MESSAGE(m_process == expectedIdentifier.m_process, "Received a policy check response for a wrong process");
	RELEASE_ASSERT_WITH_MESSAGE(m_policyCheck <= expectedIdentifier.m_policyCheck, "Received a policy check response from the future");
	return m_policyCheck == expectedIdentifier.m_policyCheck;
	}

	PolicyChecker::PolicyChecker(Frame& frame)
	: m_frame(frame)
	, m_delegateIsDecidingNavigationPolicy(false)
	, m_delegateIsHandlingUnimplementablePolicy(false)
	, m_loadType(FrameLoadType::Standard)
	{
	}

	void PolicyChecker::checkNavigationPolicy(ResourceRequest&& newRequest, const ResourceResponse& redirectResponse, NavigationPolicyDecisionFunction&& function)
	{
	checkNavigationPolicy(WTFMove(newRequest), redirectResponse, m_frame.loader().activeDocumentLoader(), { }, WTFMove(function));
	}

	CompletionHandlerCallingScope PolicyChecker::extendBlobURLLifetimeIfNecessary(ResourceRequest& request) const
	{
	if (!request.url().protocolIsBlob())
	return { };

	// Create a new temporary blobURL in case this one gets revoked during the asynchronous navigation policy decision.
	URL temporaryBlobURL = BlobURL::createPublicURL(&m_frame.document()->securityOrigin());
	blobRegistry().registerBlobURL(temporaryBlobURL, request.url());
	request.setURL(temporaryBlobURL);
	return CompletionHandler<void()>([temporaryBlobURL = WTFMove(temporaryBlobURL)] {
	blobRegistry().unregisterBlobURL(temporaryBlobURL);
	});
	}

	void PolicyChecker::checkNavigationPolicy(ResourceRequest&& request, const ResourceResponse& redirectResponse, DocumentLoader* loader, RefPtr<FormState>&& formState, NavigationPolicyDecisionFunction&& function, PolicyDecisionMode policyDecisionMode)
	{
	NavigationAction action = loader->triggeringAction();
	if (action.isEmpty()) {
	action = NavigationAction { *m_frame.document(), request, InitiatedByMainFrame::Unknown, NavigationType::Other, loader->shouldOpenExternalURLsPolicyToPropagate() };
	loader->setTriggeringAction(NavigationAction { action });
	}

	if (m_frame.page() && m_frame.page()->openedByDOMWithOpener())
	action.setOpenedByDOMWithOpener();
	action.setHasOpenedFrames(m_frame.loader().hasOpenedFrames());

	// Don't ask more than once for the same request or if we are loading an empty URL.
	// This avoids confusion on the part of the client.
	if (equalIgnoringHeaderFields(request, loader->lastCheckedRequest()) \|\| (!request.isNull() && request.url().isEmpty())) {
	if (!request.isNull() && request.url().isEmpty())
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because the URL is empty");
	else
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because the URL is the same as the last request");
	function(ResourceRequest(request), { }, NavigationPolicyDecision::ContinueLoad);
	loader->setLastCheckedRequest(WTFMove(request));
	return;
	}

	// We are always willing to show alternate content for unreachable URLs;
	// treat it like a reload so it maintains the right state for b/f list.
	auto& substituteData = loader->substituteData();
	if (substituteData.isValid() && !substituteData.failingURL().isEmpty()) {
	bool shouldContinue = true;
	#if ENABLE(CONTENT_FILTERING)
	shouldContinue = ContentFilter::continueAfterSubstituteDataRequest(*m_frame.loader().activeDocumentLoader(), substituteData);
	#endif
	if (isBackForwardLoadType(m_loadType))
	m_loadType = FrameLoadType::Reload;
	if (shouldContinue)
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because we have valid substitute data");
	else
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: not continuing with substitute data because the content filter told us not to");

	function(WTFMove(request), { }, shouldContinue ? NavigationPolicyDecision::ContinueLoad : NavigationPolicyDecision::IgnoreLoad);
	return;
	}

	if (!isAllowedByContentSecurityPolicy(request.url(), m_frame.ownerElement(), !redirectResponse.isNull())) {
	if (m_frame.ownerElement()) {
	// Fire a load event (even though we were blocked by CSP) as timing attacks would otherwise
	// reveal that the frame was blocked. This way, it looks like any other cross-origin page load.
	m_frame.ownerElement()->dispatchEvent(Event::create(eventNames().loadEvent, Event::CanBubble::No, Event::IsCancelable::No));
	}
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: ignoring because disallowed by content security policy");
	function(WTFMove(request), { }, NavigationPolicyDecision::IgnoreLoad);
	return;
	}

	loader->setLastCheckedRequest(ResourceRequest(request));

	#if USE(QUICK_LOOK)
	// Always allow QuickLook-generated URLs based on the protocol scheme.
	if (!request.isNull() && isQuickLookPreviewURL(request.url())) {
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because quicklook-generated URL");
	return function(WTFMove(request), makeWeakPtr(formState.get()), NavigationPolicyDecision::ContinueLoad);
	}
	#endif

	#if ENABLE(CONTENT_FILTERING)
	if (m_contentFilterUnblockHandler.canHandleRequest(request)) {
	RefPtr<Frame> frame { &m_frame };
	m_contentFilterUnblockHandler.requestUnblockAsync([frame](bool unblocked) {
	if (unblocked)
	frame->loader().reload();
	});
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: ignoring because ContentFilterUnblockHandler can handle the request");
	return function({ }, nullptr, NavigationPolicyDecision::IgnoreLoad);
	}
	m_contentFilterUnblockHandler = { };
	#endif

	m_frame.loader().clearProvisionalLoadForPolicyCheck();

	auto blobURLLifetimeExtension = policyDecisionMode == PolicyDecisionMode::Asynchronous ? extendBlobURLLifetimeIfNecessary(request) : CompletionHandlerCallingScope { };

	bool isInitialEmptyDocumentLoad = !m_frame.loader().stateMachine().committedFirstRealDocumentLoad() && request.url().protocolIsAbout() && !substituteData.isValid();
	auto requestIdentifier = PolicyCheckIdentifier::create();
	m_delegateIsDecidingNavigationPolicy = true;
	String suggestedFilename = action.downloadAttribute().isEmpty() ? nullAtom() : action.downloadAttribute();
	FramePolicyFunction decisionHandler = [this, function = WTFMove(function), request = ResourceRequest(request), formState = WTFMove(formState), suggestedFilename = WTFMove(suggestedFilename),
	blobURLLifetimeExtension = WTFMove(blobURLLifetimeExtension), requestIdentifier, isInitialEmptyDocumentLoad] (PolicyAction policyAction, PolicyCheckIdentifier responseIdentifier) mutable {
	if (!responseIdentifier.isValidFor(requestIdentifier)) {
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: ignoring because response is not valid for request");
	return function({ }, nullptr, NavigationPolicyDecision::IgnoreLoad);
	}

	m_delegateIsDecidingNavigationPolicy = false;

	switch (policyAction) {
	case PolicyAction::Download:
	m_frame.loader().setOriginalURLForDownloadRequest(request);
	m_frame.loader().client().startDownload(request, suggestedFilename);
	FALLTHROUGH;
	case PolicyAction::Ignore:
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: ignoring because policyAction from dispatchDecidePolicyForNavigationAction is Ignore");
	return function({ }, nullptr, NavigationPolicyDecision::IgnoreLoad);
	case PolicyAction::StopAllLoads:
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: stopping because policyAction from dispatchDecidePolicyForNavigationAction is StopAllLoads");
	function({ }, nullptr, NavigationPolicyDecision::StopAllLoads);
	return;
	case PolicyAction::Use:
	if (!m_frame.loader().client().canHandleRequest(request)) {
	handleUnimplementablePolicy(m_frame.loader().client().cannotShowURLError(request));
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: ignoring because frame loader client can't handle the request");
	return function({ }, { }, NavigationPolicyDecision::IgnoreLoad);
	}
	if (isInitialEmptyDocumentLoad)
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because this is an initial empty document");
	else
	RELEASE_LOG_IF_ALLOWED("checkNavigationPolicy: continuing because this policyAction from dispatchDecidePolicyForNavigationAction is Use");
	return function(WTFMove(request), makeWeakPtr(formState.get()), NavigationPolicyDecision::ContinueLoad);
	}
	ASSERT_NOT_REACHED();
	};

	if (isInitialEmptyDocumentLoad) {
	// We ignore the response from the client for initial empty document loads and proceed with the load synchronously.
	m_frame.loader().client().dispatchDecidePolicyForNavigationAction(action, request, redirectResponse, formState.get(), policyDecisionMode, requestIdentifier, [](PolicyAction, PolicyCheckIdentifier) { });
	decisionHandler(PolicyAction::Use, requestIdentifier);
	} else
	m_frame.loader().client().dispatchDecidePolicyForNavigationAction(action, request, redirectResponse, formState.get(), policyDecisionMode, requestIdentifier, WTFMove(decisionHandler));
	}

	void PolicyChecker::checkNewWindowPolicy(NavigationAction&& navigationAction, ResourceRequest&& request, RefPtr<FormState>&& formState, const String& frameName, NewWindowPolicyDecisionFunction&& function)
	{
	if (m_frame.document() && m_frame.document()->isSandboxed(SandboxPopups))
	return function({ }, nullptr, { }, { }, ShouldContinue::No);

	if (!DOMWindow::allowPopUp(m_frame))
	return function({ }, nullptr, { }, { }, ShouldContinue::No);

	auto blobURLLifetimeExtension = extendBlobURLLifetimeIfNecessary(request);

	auto requestIdentifier = PolicyCheckIdentifier::create();
	m_frame.loader().client().dispatchDecidePolicyForNewWindowAction(navigationAction, request, formState.get(), frameName, requestIdentifier, [frame = makeRef(m_frame), request,
	formState = WTFMove(formState), frameName, navigationAction, function = WTFMove(function), blobURLLifetimeExtension = WTFMove(blobURLLifetimeExtension),
	requestIdentifier] (PolicyAction policyAction, PolicyCheckIdentifier responseIdentifier) mutable {

	if (!responseIdentifier.isValidFor(requestIdentifier))
	return function({ }, nullptr, { }, { }, ShouldContinue::No);

	switch (policyAction) {
	case PolicyAction::Download:
	frame->loader().client().startDownload(request);
	FALLTHROUGH;
	case PolicyAction::Ignore:
	function({ }, nullptr, { }, { }, ShouldContinue::No);
	return;
	case PolicyAction::StopAllLoads:
	ASSERT_NOT_REACHED();
	function({ }, nullptr, { }, { }, ShouldContinue::No);
	return;
	case PolicyAction::Use:
	function(request, makeWeakPtr(formState.get()), frameName, navigationAction, ShouldContinue::Yes);
	return;
	}
	ASSERT_NOT_REACHED();
	});
	}

	void PolicyChecker::stopCheck()
	{
	m_frame.loader().client().cancelPolicyCheck();
	}

	void PolicyChecker::cannotShowMIMEType(const ResourceResponse& response)
	{
	handleUnimplementablePolicy(m_frame.loader().client().cannotShowMIMETypeError(response));
	}

	void PolicyChecker::handleUnimplementablePolicy(const ResourceError& error)
	{
	m_delegateIsHandlingUnimplementablePolicy = true;
	m_frame.loader().client().dispatchUnableToImplementPolicy(error);
	m_delegateIsHandlingUnimplementablePolicy = false;
	}

	} // namespace WebCore

	#undef IS_ALLOWED
	#undef PAGE_ID
	#undef FRAME_ID
	#undef RELEASE_LOG_IF_ALLOWED