third_party/WebKit/Source/web/AssociatedURLLoader.cpp

/*
 * Copyright (C) 2010, 2011, 2012 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.
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 * 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
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 */

#include "web/AssociatedURLLoader.h"

#include "core/dom/ContextLifecycleObserver.h"
#include "core/fetch/CrossOriginAccessControl.h"
#include "core/fetch/FetchUtils.h"
#include "core/loader/DocumentThreadableLoader.h"
#include "core/loader/DocumentThreadableLoaderClient.h"
#include "platform/Timer.h"
#include "platform/exported/WrappedResourceRequest.h"
#include "platform/exported/WrappedResourceResponse.h"
#include "platform/network/HTTPParsers.h"
#include "platform/network/ResourceError.h"
#include "public/platform/WebHTTPHeaderVisitor.h"
#include "public/platform/WebString.h"
#include "public/platform/WebURLError.h"
#include "public/platform/WebURLLoaderClient.h"
#include "public/platform/WebURLRequest.h"
#include "public/web/WebDataSource.h"
#include "web/WebLocalFrameImpl.h"
#include "wtf/HashSet.h"
#include "wtf/PtrUtil.h"
#include "wtf/text/WTFString.h"
#include <limits.h>
#include <memory>

namespace blink {

namespace {

class HTTPRequestHeaderValidator : public WebHTTPHeaderVisitor {
  WTF_MAKE_NONCOPYABLE(HTTPRequestHeaderValidator);

 public:
  HTTPRequestHeaderValidator() : m_isSafe(true) {}
  ~HTTPRequestHeaderValidator() override {}

  void visitHeader(const WebString& name, const WebString& value) override;
  bool isSafe() const { return m_isSafe; }

 private:
  bool m_isSafe;
};

void HTTPRequestHeaderValidator::visitHeader(const WebString& name,
                                             const WebString& value) {
  m_isSafe = m_isSafe && isValidHTTPToken(name) &&
             !FetchUtils::isForbiddenHeaderName(name) &&
             isValidHTTPHeaderValue(value);
}

}  // namespace

// This class bridges the interface differences between WebCore and WebKit
// loader clients.
// It forwards its ThreadableLoaderClient notifications to a WebURLLoaderClient.
class AssociatedURLLoader::ClientAdapter final
    : public DocumentThreadableLoaderClient {
  WTF_MAKE_NONCOPYABLE(ClientAdapter);

 public:
  static std::unique_ptr<ClientAdapter> create(AssociatedURLLoader*,
                                               WebURLLoaderClient*,
                                               const WebURLLoaderOptions&);

  // ThreadableLoaderClient
  void didSendData(unsigned long long /*bytesSent*/,
                   unsigned long long /*totalBytesToBeSent*/) override;
  void didReceiveResponse(unsigned long,
                          const ResourceResponse&,
                          std::unique_ptr<WebDataConsumerHandle>) override;
  void didDownloadData(int /*dataLength*/) override;
  void didReceiveData(const char*, unsigned /*dataLength*/) override;
  void didReceiveCachedMetadata(const char*, int /*dataLength*/) override;
  void didFinishLoading(unsigned long /*identifier*/,
                        double /*finishTime*/) override;
  void didFail(const ResourceError&) override;
  void didFailRedirectCheck() override;
  // DocumentThreadableLoaderClient
  void willFollowRedirect(
      ResourceRequest& /*newRequest*/,
      const ResourceResponse& /*redirectResponse*/) override;

  // Sets an error to be reported back to the client, asychronously.
  void setDelayedError(const ResourceError&);

  // Enables forwarding of error notifications to the WebURLLoaderClient. These
  // must be deferred until after the call to
  // AssociatedURLLoader::loadAsynchronously() completes.
  void enableErrorNotifications();

  // Stops loading and releases the DocumentThreadableLoader as early as
  // possible.
  WebURLLoaderClient* releaseClient() {
    WebURLLoaderClient* client = m_client;
    m_client = nullptr;
    return client;
  }

 private:
  ClientAdapter(AssociatedURLLoader*,
                WebURLLoaderClient*,
                const WebURLLoaderOptions&);

  void notifyError(TimerBase*);

  AssociatedURLLoader* m_loader;
  WebURLLoaderClient* m_client;
  WebURLLoaderOptions m_options;
  WebURLError m_error;

  Timer<ClientAdapter> m_errorTimer;
  bool m_enableErrorNotifications;
  bool m_didFail;
};

std::unique_ptr<AssociatedURLLoader::ClientAdapter>
AssociatedURLLoader::ClientAdapter::create(AssociatedURLLoader* loader,
                                           WebURLLoaderClient* client,
                                           const WebURLLoaderOptions& options) {
  return wrapUnique(new ClientAdapter(loader, client, options));
}

AssociatedURLLoader::ClientAdapter::ClientAdapter(
    AssociatedURLLoader* loader,
    WebURLLoaderClient* client,
    const WebURLLoaderOptions& options)
    : m_loader(loader),
      m_client(client),
      m_options(options),
      m_errorTimer(this, &ClientAdapter::notifyError),
      m_enableErrorNotifications(false),
      m_didFail(false) {
  DCHECK(m_loader);
  DCHECK(m_client);
}

void AssociatedURLLoader::ClientAdapter::willFollowRedirect(
    ResourceRequest& newRequest,
    const ResourceResponse& redirectResponse) {
  if (!m_client)
    return;

  WrappedResourceRequest wrappedNewRequest(newRequest);
  WrappedResourceResponse wrappedRedirectResponse(redirectResponse);
  // TODO(ricea): Do we need to set encodedDataLength here?
  m_client->willFollowRedirect(m_loader, wrappedNewRequest,
                               wrappedRedirectResponse, 0);
}

void AssociatedURLLoader::ClientAdapter::didSendData(
    unsigned long long bytesSent,
    unsigned long long totalBytesToBeSent) {
  if (!m_client)
    return;

  m_client->didSendData(m_loader, bytesSent, totalBytesToBeSent);
}

void AssociatedURLLoader::ClientAdapter::didReceiveResponse(
    unsigned long,
    const ResourceResponse& response,
    std::unique_ptr<WebDataConsumerHandle> handle) {
  ASSERT_UNUSED(handle, !handle);
  if (!m_client)
    return;

  if (m_options.exposeAllResponseHeaders ||
      m_options.crossOriginRequestPolicy !=
          WebURLLoaderOptions::CrossOriginRequestPolicyUseAccessControl) {
    // Use the original ResourceResponse.
    m_client->didReceiveResponse(m_loader, WrappedResourceResponse(response));
    return;
  }

  HTTPHeaderSet exposedHeaders;
  extractCorsExposedHeaderNamesList(response, exposedHeaders);
  HTTPHeaderSet blockedHeaders;
  for (const auto& header : response.httpHeaderFields()) {
    if (FetchUtils::isForbiddenResponseHeaderName(header.key) ||
        (!isOnAccessControlResponseHeaderWhitelist(header.key) &&
         !exposedHeaders.contains(header.key)))
      blockedHeaders.add(header.key);
  }

  if (blockedHeaders.isEmpty()) {
    // Use the original ResourceResponse.
    m_client->didReceiveResponse(m_loader, WrappedResourceResponse(response));
    return;
  }

  // If there are blocked headers, copy the response so we can remove them.
  WebURLResponse validatedResponse = WrappedResourceResponse(response);
  for (const auto& header : blockedHeaders)
    validatedResponse.clearHTTPHeaderField(header);
  m_client->didReceiveResponse(m_loader, validatedResponse);
}

void AssociatedURLLoader::ClientAdapter::didDownloadData(int dataLength) {
  if (!m_client)
    return;

  m_client->didDownloadData(m_loader, dataLength, -1);
}

void AssociatedURLLoader::ClientAdapter::didReceiveData(const char* data,
                                                        unsigned dataLength) {
  if (!m_client)
    return;

  CHECK_LE(dataLength, static_cast<unsigned>(std::numeric_limits<int>::max()));

  m_client->didReceiveData(m_loader, data, dataLength, -1, dataLength);
}

void AssociatedURLLoader::ClientAdapter::didReceiveCachedMetadata(
    const char* data,
    int dataLength) {
  if (!m_client)
    return;

  m_client->didReceiveCachedMetadata(m_loader, data, dataLength);
}

void AssociatedURLLoader::ClientAdapter::didFinishLoading(
    unsigned long identifier,
    double finishTime) {
  if (!m_client)
    return;

  m_loader->clientAdapterDone();

  releaseClient()->didFinishLoading(
      m_loader, finishTime, WebURLLoaderClient::kUnknownEncodedDataLength);
  // |this| may be dead here.
}

void AssociatedURLLoader::ClientAdapter::didFail(const ResourceError& error) {
  if (!m_client)
    return;

  m_loader->clientAdapterDone();

  m_didFail = true;
  m_error = WebURLError(error);
  if (m_enableErrorNotifications)
    notifyError(&m_errorTimer);
}

void AssociatedURLLoader::ClientAdapter::didFailRedirectCheck() {
  didFail(ResourceError());
}

void AssociatedURLLoader::ClientAdapter::enableErrorNotifications() {
  m_enableErrorNotifications = true;
  // If an error has already been received, start a timer to report it to the
  // client after AssociatedURLLoader::loadAsynchronously has returned to the
  // caller.
  if (m_didFail)
    m_errorTimer.startOneShot(0, BLINK_FROM_HERE);
}

void AssociatedURLLoader::ClientAdapter::notifyError(TimerBase* timer) {
  ASSERT_UNUSED(timer, timer == &m_errorTimer);

  if (!m_client)
    return;

  releaseClient()->didFail(m_loader, m_error);
  // |this| may be dead here.
}

class AssociatedURLLoader::Observer final : public GarbageCollected<Observer>,
                                            public ContextLifecycleObserver {
  USING_GARBAGE_COLLECTED_MIXIN(Observer);

 public:
  Observer(AssociatedURLLoader* parent, Document* document)
      : ContextLifecycleObserver(document), m_parent(parent) {}

  void dispose() {
    m_parent = nullptr;
    clearContext();
  }

  void contextDestroyed() override {
    if (m_parent)
      m_parent->documentDestroyed();
  }

  DEFINE_INLINE_VIRTUAL_TRACE() { ContextLifecycleObserver::trace(visitor); }

  AssociatedURLLoader* m_parent;
};

AssociatedURLLoader::AssociatedURLLoader(WebLocalFrameImpl* frameImpl,
                                         const WebURLLoaderOptions& options)
    : m_client(nullptr),
      m_options(options),
      m_observer(new Observer(this, frameImpl->frame()->document())) {}

AssociatedURLLoader::~AssociatedURLLoader() {
  cancel();
}

#define STATIC_ASSERT_ENUM(a, b)                            \
  static_assert(static_cast<int>(a) == static_cast<int>(b), \
                "mismatching enum: " #a)

STATIC_ASSERT_ENUM(WebURLLoaderOptions::CrossOriginRequestPolicyDeny,
                   DenyCrossOriginRequests);
STATIC_ASSERT_ENUM(
    WebURLLoaderOptions::CrossOriginRequestPolicyUseAccessControl,
    UseAccessControl);
STATIC_ASSERT_ENUM(WebURLLoaderOptions::CrossOriginRequestPolicyAllow,
                   AllowCrossOriginRequests);

STATIC_ASSERT_ENUM(WebURLLoaderOptions::ConsiderPreflight, ConsiderPreflight);
STATIC_ASSERT_ENUM(WebURLLoaderOptions::ForcePreflight, ForcePreflight);
STATIC_ASSERT_ENUM(WebURLLoaderOptions::PreventPreflight, PreventPreflight);

void AssociatedURLLoader::loadSynchronously(const WebURLRequest& request,
                                            WebURLResponse& response,
                                            WebURLError& error,
                                            WebData& data,
                                            int64_t& encodedDataLength) {
  DCHECK(0);  // Synchronous loading is not supported.
}

void AssociatedURLLoader::loadAsynchronously(const WebURLRequest& request,
                                             WebURLLoaderClient* client) {
  DCHECK(!m_client);
  DCHECK(!m_loader);
  DCHECK(!m_clientAdapter);

  DCHECK(client);

  bool allowLoad = true;
  WebURLRequest newRequest(request);
  if (m_options.untrustedHTTP) {
    WebString method = newRequest.httpMethod();
    allowLoad = m_observer && isValidHTTPToken(method) &&
                FetchUtils::isUsefulMethod(method);
    if (allowLoad) {
      newRequest.setHTTPMethod(FetchUtils::normalizeMethod(method));
      HTTPRequestHeaderValidator validator;
      newRequest.visitHTTPHeaderFields(&validator);
      allowLoad = validator.isSafe();
    }
  }

  m_client = client;
  m_clientAdapter = ClientAdapter::create(this, client, m_options);

  if (allowLoad) {
    ThreadableLoaderOptions options;
    options.preflightPolicy =
        static_cast<PreflightPolicy>(m_options.preflightPolicy);
    options.crossOriginRequestPolicy = static_cast<CrossOriginRequestPolicy>(
        m_options.crossOriginRequestPolicy);

    ResourceLoaderOptions resourceLoaderOptions;
    resourceLoaderOptions.allowCredentials = m_options.allowCredentials
                                                 ? AllowStoredCredentials
                                                 : DoNotAllowStoredCredentials;
    resourceLoaderOptions.dataBufferingPolicy = DoNotBufferData;

    const ResourceRequest& webcoreRequest = newRequest.toResourceRequest();
    if (webcoreRequest.requestContext() ==
        WebURLRequest::RequestContextUnspecified) {
      // FIXME: We load URLs without setting a TargetType (and therefore a
      // request context) in several places in content/
      // (P2PPortAllocatorSession::AllocateLegacyRelaySession, for example).
      // Remove this once those places are patched up.
      newRequest.setRequestContext(WebURLRequest::RequestContextInternal);
    }

    Document* document = toDocument(m_observer->lifecycleContext());
    DCHECK(document);
    m_loader = DocumentThreadableLoader::create(
        *document, m_clientAdapter.get(), options, resourceLoaderOptions);
    m_loader->start(webcoreRequest);
  }

  if (!m_loader) {
    // FIXME: return meaningful error codes.
    m_clientAdapter->didFail(ResourceError());
  }
  m_clientAdapter->enableErrorNotifications();
}

void AssociatedURLLoader::cancel() {
  disposeObserver();
  cancelLoader();
  releaseClient();
}

void AssociatedURLLoader::clientAdapterDone() {
  disposeObserver();
  releaseClient();
}

void AssociatedURLLoader::cancelLoader() {
  if (!m_clientAdapter)
    return;

  // Prevent invocation of the WebURLLoaderClient methods.
  m_clientAdapter->releaseClient();

  if (m_loader) {
    m_loader->cancel();
    m_loader = nullptr;
  }
  m_clientAdapter.reset();
}

void AssociatedURLLoader::setDefersLoading(bool defersLoading) {
  if (m_loader)
    m_loader->setDefersLoading(defersLoading);
}

void AssociatedURLLoader::setLoadingTaskRunner(blink::WebTaskRunner*) {
  // TODO(alexclarke): Maybe support this one day if it proves worthwhile.
}

void AssociatedURLLoader::documentDestroyed() {
  disposeObserver();
  cancelLoader();

  if (!m_client)
    return;

  releaseClient()->didFail(this, ResourceError());
  // |this| may be dead here.
}

void AssociatedURLLoader::disposeObserver() {
  if (!m_observer)
    return;

  // TODO(tyoshino): Remove this assert once Document is fixed so that
  // contextDestroyed() is invoked for all kinds of Documents.
  //
  // Currently, the method of detecting Document destruction implemented here
  // doesn't work for all kinds of Documents. In case we reached here after
  // the Oilpan is destroyed, we just crash the renderer process to prevent
  // UaF.
  //
  // We could consider just skipping the rest of code in case
  // ThreadState::current() is null. However, the fact we reached here
  // without cancelling the loader means that it's possible there're some
  // non-Blink non-on-heap objects still facing on-heap Blink objects. E.g.
  // there could be a WebURLLoader instance behind the
  // DocumentThreadableLoader instance. So, for safety, we chose to just
  // crash here.
  RELEASE_ASSERT(ThreadState::current());

  m_observer->dispose();
  m_observer = nullptr;
}

}  // namespace blink