root/Source/core/fetch/ResourceLoader.cpp

DEFINITIONS

1. m_resource
2. create
3. m_requestCountTracker
4. releaseResources
5. init
6. start
7. changeToSynchronous
8. setDefersLoading
9. attachThreadedDataReceiver
10. didDownloadData
11. didFinishLoadingOnePart
12. didChangePriority
13. cancelIfNotFinishing
14. cancel
15. cancel
16. willSendRequest
17. didReceiveCachedMetadata
18. didSendData
19. responseNeedsAccessControlCheck
20. didReceiveResponse
21. didReceiveData
22. didFinishLoading
23. didFail
24. isLoadedBy
25. requestSynchronously
26. applyOptions

/*
 * Copyright (C) 2006, 2007, 2010, 2011 Apple Inc. All rights reserved.
 *           (C) 2007 Graham Dennis (graham.dennis@gmail.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 Computer, 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 "core/fetch/ResourceLoader.h"

#include "core/fetch/Resource.h"
#include "core/fetch/ResourceLoaderHost.h"
#include "core/fetch/ResourcePtr.h"
#include "platform/Logging.h"
#include "platform/SharedBuffer.h"
#include "platform/exported/WrappedResourceRequest.h"
#include "platform/exported/WrappedResourceResponse.h"
#include "platform/network/ResourceError.h"
#include "public/platform/Platform.h"
#include "public/platform/WebData.h"
#include "public/platform/WebThreadedDataReceiver.h"
#include "public/platform/WebURLError.h"
#include "public/platform/WebURLRequest.h"
#include "public/platform/WebURLResponse.h"
#include "wtf/Assertions.h"
#include "wtf/CurrentTime.h"

namespace WebCore {

ResourceLoader::RequestCountTracker::RequestCountTracker(ResourceLoaderHost* host, Resource* resource)
    : m_host(host)
    , m_resource(resource)
{
    m_host->incrementRequestCount(m_resource);
}

ResourceLoader::RequestCountTracker::~RequestCountTracker()
{
    m_host->decrementRequestCount(m_resource);
}

PassRefPtr<ResourceLoader> ResourceLoader::create(ResourceLoaderHost* host, Resource* resource, const ResourceRequest& request, const ResourceLoaderOptions& options)
{
    RefPtr<ResourceLoader> loader(adoptRef(new ResourceLoader(host, resource, options)));
    loader->init(request);
    return loader.release();
}

ResourceLoader::ResourceLoader(ResourceLoaderHost* host, Resource* resource, const ResourceLoaderOptions& options)
    : m_host(host)
    , m_notifiedLoadComplete(false)
    , m_defersLoading(host->defersLoading())
    , m_options(options)
    , m_resource(resource)
    , m_state(Initialized)
    , m_connectionState(ConnectionStateNew)
    , m_requestCountTracker(adoptPtr(new RequestCountTracker(host, resource)))
{
}

ResourceLoader::~ResourceLoader()
{
    ASSERT(m_state == Terminated);
}

void ResourceLoader::releaseResources()
{
    ASSERT(m_state != Terminated);
    ASSERT(m_notifiedLoadComplete);
    m_requestCountTracker.clear();
    m_host->didLoadResource(m_resource);
    if (m_state == Terminated)
        return;
    m_resource->clearLoader();
    m_host->willTerminateResourceLoader(this);

    ASSERT(m_state != Terminated);

    // It's possible that when we release the loader, it will be
    // deallocated and release the last reference to this object.
    // We need to retain to avoid accessing the object after it
    // has been deallocated and also to avoid reentering this method.
    RefPtr<ResourceLoader> protector(this);

    m_host.clear();
    m_state = Terminated;

    if (m_loader) {
        m_loader->cancel();
        m_loader.clear();
    }

    m_deferredRequest = ResourceRequest();
}

void ResourceLoader::init(const ResourceRequest& passedRequest)
{
    ResourceRequest request(passedRequest);
    m_host->willSendRequest(m_resource->identifier(), request, ResourceResponse(), m_options.initiatorInfo);
    request.setReportLoadTiming(true);
    ASSERT(m_state != Terminated);
    ASSERT(!request.isNull());
    m_originalRequest = m_request = applyOptions(request);
    m_resource->updateRequest(request);
    m_host->didInitializeResourceLoader(this);
}

void ResourceLoader::start()
{
    ASSERT(!m_loader);
    ASSERT(!m_request.isNull());
    ASSERT(m_deferredRequest.isNull());

    m_host->willStartLoadingResource(m_request);

    if (m_options.synchronousPolicy == RequestSynchronously) {
        requestSynchronously();
        return;
    }

    if (m_defersLoading) {
        m_deferredRequest = m_request;
        return;
    }

    if (m_state == Terminated)
        return;

    RELEASE_ASSERT(m_connectionState == ConnectionStateNew);
    m_connectionState = ConnectionStateStarted;

    m_loader = adoptPtr(blink::Platform::current()->createURLLoader());
    ASSERT(m_loader);
    blink::WrappedResourceRequest wrappedRequest(m_request);
    m_loader->loadAsynchronously(wrappedRequest, this);
}

void ResourceLoader::changeToSynchronous()
{
    ASSERT(m_options.synchronousPolicy == RequestAsynchronously);
    ASSERT(m_loader);
    m_loader->cancel();
    m_loader.clear();
    m_request.setPriority(ResourceLoadPriorityHighest);
    m_connectionState = ConnectionStateNew;
    requestSynchronously();
}

void ResourceLoader::setDefersLoading(bool defers)
{
    m_defersLoading = defers;
    if (m_loader)
        m_loader->setDefersLoading(defers);
    if (!defers && !m_deferredRequest.isNull()) {
        m_request = applyOptions(m_deferredRequest);
        m_deferredRequest = ResourceRequest();
        start();
    }
}

void ResourceLoader::attachThreadedDataReceiver(PassOwnPtr<blink::WebThreadedDataReceiver> threadedDataReceiver)
{
    if (m_loader) {
        // The implementor of the WebURLLoader assumes ownership of the
        // threaded data receiver if it signals that it got successfully
        // attached.
        blink::WebThreadedDataReceiver* rawThreadedDataReceiver = threadedDataReceiver.leakPtr();
        if (!m_loader->attachThreadedDataReceiver(rawThreadedDataReceiver))
            delete rawThreadedDataReceiver;
    }
}

void ResourceLoader::didDownloadData(blink::WebURLLoader*, int length, int encodedDataLength)
{
    RefPtr<ResourceLoader> protect(this);
    RELEASE_ASSERT(m_connectionState == ConnectionStateReceivedResponse);
    m_host->didDownloadData(m_resource, length, encodedDataLength);
    m_resource->didDownloadData(length);
}

void ResourceLoader::didFinishLoadingOnePart(double finishTime, int64 encodedDataLength)
{
    // If load has been cancelled after finishing (which could happen with a
    // JavaScript that changes the window location), do nothing.
    if (m_state == Terminated)
        return;

    if (m_notifiedLoadComplete)
        return;
    m_notifiedLoadComplete = true;
    m_host->didFinishLoading(m_resource, finishTime, encodedDataLength);
}

void ResourceLoader::didChangePriority(ResourceLoadPriority loadPriority, int intraPriorityValue)
{
    if (m_loader) {
        m_host->didChangeLoadingPriority(m_resource, loadPriority, intraPriorityValue);
        m_loader->didChangePriority(static_cast<blink::WebURLRequest::Priority>(loadPriority), intraPriorityValue);
    }
}

void ResourceLoader::cancelIfNotFinishing()
{
    if (m_state != Initialized)
        return;
    cancel();
}

void ResourceLoader::cancel()
{
    cancel(ResourceError());
}

void ResourceLoader::cancel(const ResourceError& error)
{
    // If the load has already completed - succeeded, failed, or previously cancelled - do nothing.
    if (m_state == Terminated)
        return;
    if (m_state == Finishing) {
        releaseResources();
        return;
    }

    ResourceError nonNullError = error.isNull() ? ResourceError::cancelledError(m_request.url()) : error;

    // This function calls out to clients at several points that might do
    // something that causes the last reference to this object to go away.
    RefPtr<ResourceLoader> protector(this);

    WTF_LOG(ResourceLoading, "Cancelled load of '%s'.\n", m_resource->url().string().latin1().data());
    if (m_state == Initialized)
        m_state = Finishing;
    m_resource->setResourceError(nonNullError);

    if (m_loader) {
        m_connectionState = ConnectionStateCanceled;
        m_loader->cancel();
        m_loader.clear();
    }

    if (!m_notifiedLoadComplete) {
        m_notifiedLoadComplete = true;
        m_host->didFailLoading(m_resource, nonNullError);
    }

    if (m_state == Finishing)
        m_resource->error(Resource::LoadError);
    if (m_state != Terminated)
        releaseResources();
}

void ResourceLoader::willSendRequest(blink::WebURLLoader*, blink::WebURLRequest& passedRequest, const blink::WebURLResponse& passedRedirectResponse)
{
    RefPtr<ResourceLoader> protect(this);

    ResourceRequest& request(applyOptions(passedRequest.toMutableResourceRequest()));
    ASSERT(!request.isNull());
    const ResourceResponse& redirectResponse(passedRedirectResponse.toResourceResponse());
    ASSERT(!redirectResponse.isNull());
    if (!m_host->canAccessRedirect(m_resource, request, redirectResponse, m_options)) {
        cancel();
        return;
    }

    applyOptions(request); // canAccessRedirect() can modify m_options so we should re-apply it.
    m_host->redirectReceived(m_resource, redirectResponse);
    m_resource->willSendRequest(request, redirectResponse);
    if (request.isNull() || m_state == Terminated)
        return;

    m_host->willSendRequest(m_resource->identifier(), request, redirectResponse, m_options.initiatorInfo);
    request.setReportLoadTiming(true);
    ASSERT(!request.isNull());
    m_resource->updateRequest(request);
    m_request = request;
}

void ResourceLoader::didReceiveCachedMetadata(blink::WebURLLoader*, const char* data, int length)
{
    RELEASE_ASSERT(m_connectionState == ConnectionStateReceivedResponse || m_connectionState == ConnectionStateReceivingData);
    ASSERT(m_state == Initialized);
    m_resource->setSerializedCachedMetadata(data, length);
}

void ResourceLoader::didSendData(blink::WebURLLoader*, unsigned long long bytesSent, unsigned long long totalBytesToBeSent)
{
    ASSERT(m_state == Initialized);
    RefPtr<ResourceLoader> protect(this);
    m_resource->didSendData(bytesSent, totalBytesToBeSent);
}

bool ResourceLoader::responseNeedsAccessControlCheck() const
{
    // If the fetch was (potentially) CORS enabled, an access control check of the response is required.
    return m_options.corsEnabled == IsCORSEnabled;
}

void ResourceLoader::didReceiveResponse(blink::WebURLLoader*, const blink::WebURLResponse& response)
{
    ASSERT(!response.isNull());
    ASSERT(m_state == Initialized);

    bool isMultipartPayload = response.isMultipartPayload();
    bool isValidStateTransition = (m_connectionState == ConnectionStateStarted || m_connectionState == ConnectionStateReceivedResponse);
    // In the case of multipart loads, calls to didReceiveData & didReceiveResponse can be interleaved.
    RELEASE_ASSERT(isMultipartPayload || isValidStateTransition);
    m_connectionState = ConnectionStateReceivedResponse;

    const ResourceResponse& resourceResponse = response.toResourceResponse();

    if (responseNeedsAccessControlCheck()) {
        // If the response successfully validated a cached resource, perform
        // the access control with respect to it. Need to do this right here
        // before the resource switches clients over to that validated resource.
        Resource* resource = m_resource;
        if (resource->isCacheValidator() && resourceResponse.httpStatusCode() == 304)
            resource = m_resource->resourceToRevalidate();
        else
            m_resource->setResponse(resourceResponse);
        if (!m_host->canAccessResource(resource, m_options.securityOrigin.get(), response.url())) {
            m_host->didReceiveResponse(m_resource, resourceResponse);
            cancel();
            return;
        }
    }

    // Reference the object in this method since the additional processing can do
    // anything including removing the last reference to this object.
    RefPtr<ResourceLoader> protect(this);
    m_resource->responseReceived(resourceResponse);
    if (m_state == Terminated)
        return;

    m_host->didReceiveResponse(m_resource, resourceResponse);

    if (response.toResourceResponse().isMultipart()) {
        // We don't count multiParts in a ResourceFetcher's request count
        m_requestCountTracker.clear();
        if (!m_resource->isImage()) {
            cancel();
            return;
        }
    } else if (isMultipartPayload) {
        // Since a subresource loader does not load multipart sections progressively, data was delivered to the loader all at once.
        // After the first multipart section is complete, signal to delegates that this load is "finished"
        m_host->subresourceLoaderFinishedLoadingOnePart(this);
        didFinishLoadingOnePart(0, blink::WebURLLoaderClient::kUnknownEncodedDataLength);
    }

    if (m_resource->response().httpStatusCode() < 400 || m_resource->shouldIgnoreHTTPStatusCodeErrors())
        return;
    m_state = Finishing;

    if (!m_notifiedLoadComplete) {
        m_notifiedLoadComplete = true;
        m_host->didFailLoading(m_resource, ResourceError::cancelledError(m_request.url()));
    }

    m_resource->error(Resource::LoadError);
    cancel();
}

void ResourceLoader::didReceiveData(blink::WebURLLoader*, const char* data, int length, int encodedDataLength)
{
    RELEASE_ASSERT(m_connectionState == ConnectionStateReceivedResponse || m_connectionState == ConnectionStateReceivingData);
    m_connectionState = ConnectionStateReceivingData;

    // It is possible to receive data on uninitialized resources if it had an error status code, and we are running a nested message
    // loop. When this occurs, ignoring the data is the correct action.
    if (m_resource->response().httpStatusCode() >= 400 && !m_resource->shouldIgnoreHTTPStatusCodeErrors())
        return;
    ASSERT(m_state == Initialized);

    // Reference the object in this method since the additional processing can do
    // anything including removing the last reference to this object.
    RefPtr<ResourceLoader> protect(this);

    // FIXME: If we get a resource with more than 2B bytes, this code won't do the right thing.
    // However, with today's computers and networking speeds, this won't happen in practice.
    // Could be an issue with a giant local file.
    m_host->didReceiveData(m_resource, data, length, encodedDataLength);
    m_resource->appendData(data, length);
}

void ResourceLoader::didFinishLoading(blink::WebURLLoader*, double finishTime, int64 encodedDataLength)
{
    RELEASE_ASSERT(m_connectionState == ConnectionStateReceivedResponse || m_connectionState == ConnectionStateReceivingData);
    m_connectionState = ConnectionStateFinishedLoading;
    if (m_state != Initialized)
        return;
    ASSERT(m_state != Terminated);
    WTF_LOG(ResourceLoading, "Received '%s'.", m_resource->url().string().latin1().data());

    RefPtr<ResourceLoader> protect(this);
    ResourcePtr<Resource> protectResource(m_resource);
    m_state = Finishing;
    didFinishLoadingOnePart(finishTime, encodedDataLength);
    m_resource->finish(finishTime);

    // If the load has been cancelled by a delegate in response to didFinishLoad(), do not release
    // the resources a second time, they have been released by cancel.
    if (m_state == Terminated)
        return;
    releaseResources();
}

void ResourceLoader::didFail(blink::WebURLLoader*, const blink::WebURLError& error)
{
    m_connectionState = ConnectionStateFailed;
    ASSERT(m_state != Terminated);
    WTF_LOG(ResourceLoading, "Failed to load '%s'.\n", m_resource->url().string().latin1().data());

    RefPtr<ResourceLoader> protect(this);
    RefPtr<ResourceLoaderHost> protectHost(m_host);
    ResourcePtr<Resource> protectResource(m_resource);
    m_state = Finishing;
    m_resource->setResourceError(error);

    if (!m_notifiedLoadComplete) {
        m_notifiedLoadComplete = true;
        m_host->didFailLoading(m_resource, error);
    }

    m_resource->error(Resource::LoadError);

    if (m_state == Terminated)
        return;

    releaseResources();
}

bool ResourceLoader::isLoadedBy(ResourceLoaderHost* loader) const
{
    return m_host->isLoadedBy(loader);
}

void ResourceLoader::requestSynchronously()
{
    OwnPtr<blink::WebURLLoader> loader = adoptPtr(blink::Platform::current()->createURLLoader());
    ASSERT(loader);

    // downloadToFile is not supported for synchronous requests.
    ASSERT(!m_request.downloadToFile());

    RefPtr<ResourceLoader> protect(this);
    RefPtr<ResourceLoaderHost> protectHost(m_host);
    ResourcePtr<Resource> protectResource(m_resource);

    RELEASE_ASSERT(m_connectionState == ConnectionStateNew);
    m_connectionState = ConnectionStateStarted;

    blink::WrappedResourceRequest requestIn(m_request);
    blink::WebURLResponse responseOut;
    responseOut.initialize();
    blink::WebURLError errorOut;
    blink::WebData dataOut;
    loader->loadSynchronously(requestIn, responseOut, errorOut, dataOut);
    if (errorOut.reason) {
        didFail(0, errorOut);
        return;
    }
    didReceiveResponse(0, responseOut);
    if (m_state == Terminated)
        return;
    RefPtr<ResourceLoadInfo> resourceLoadInfo = responseOut.toResourceResponse().resourceLoadInfo();
    int64 encodedDataLength = resourceLoadInfo ? resourceLoadInfo->encodedDataLength : blink::WebURLLoaderClient::kUnknownEncodedDataLength;
    m_host->didReceiveData(m_resource, dataOut.data(), dataOut.size(), encodedDataLength);
    m_resource->setResourceBuffer(dataOut);
    didFinishLoading(0, monotonicallyIncreasingTime(), encodedDataLength);
}

ResourceRequest& ResourceLoader::applyOptions(ResourceRequest& request) const
{
    request.setAllowStoredCredentials(m_options.allowCredentials == AllowStoredCredentials);
    return request;
}

}