/*
 * 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.
 *     * 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 "web/WebAssociatedURLLoaderImpl.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/WebURLRequest.h"
#include "public/web/WebAssociatedURLLoaderClient.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
// WebAssociatedURLLoaderClient.
class WebAssociatedURLLoaderImpl::ClientAdapter final
    : public DocumentThreadableLoaderClient {
  WTF_MAKE_NONCOPYABLE(ClientAdapter);

 public:
  static std::unique_ptr<ClientAdapter> create(
      WebAssociatedURLLoaderImpl*,
      WebAssociatedURLLoaderClient*,
      const WebAssociatedURLLoaderOptions&);

  // 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
  bool willFollowRedirect(
      const 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
  // WebAssociatedURLLoaderClient. These
  // must be deferred until after the call to
  // WebAssociatedURLLoader::loadAsynchronously() completes.
  void enableErrorNotifications();

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

 private:
  ClientAdapter(WebAssociatedURLLoaderImpl*,
                WebAssociatedURLLoaderClient*,
                const WebAssociatedURLLoaderOptions&);

  void notifyError(TimerBase*);

  WebAssociatedURLLoaderImpl* m_loader;
  WebAssociatedURLLoaderClient* m_client;
  WebAssociatedURLLoaderOptions m_options;
  WebURLError m_error;

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

std::unique_ptr<WebAssociatedURLLoaderImpl::ClientAdapter>
WebAssociatedURLLoaderImpl::ClientAdapter::create(
    WebAssociatedURLLoaderImpl* loader,
    WebAssociatedURLLoaderClient* client,
    const WebAssociatedURLLoaderOptions& options) {
  return WTF::wrapUnique(new ClientAdapter(loader, client, options));
}

WebAssociatedURLLoaderImpl::ClientAdapter::ClientAdapter(
    WebAssociatedURLLoaderImpl* loader,
    WebAssociatedURLLoaderClient* client,
    const WebAssociatedURLLoaderOptions& 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);
}

bool WebAssociatedURLLoaderImpl::ClientAdapter::willFollowRedirect(
    const ResourceRequest& newRequest,
    const ResourceResponse& redirectResponse) {
  if (!m_client)
    return true;

  WrappedResourceRequest wrappedNewRequest(newRequest);
  WrappedResourceResponse wrappedRedirectResponse(redirectResponse);
  return m_client->willFollowRedirect(wrappedNewRequest,
                                      wrappedRedirectResponse);
}

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

  m_client->didSendData(bytesSent, totalBytesToBeSent);
}

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

  if (m_options.exposeAllResponseHeaders ||
      m_options.crossOriginRequestPolicy !=
          WebAssociatedURLLoaderOptions::
              CrossOriginRequestPolicyUseAccessControl) {
    // Use the original ResourceResponse.
    m_client->didReceiveResponse(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(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(validatedResponse);
}

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

  m_client->didDownloadData(dataLength);
}

void WebAssociatedURLLoaderImpl::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(data, dataLength);
}

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

  m_client->didReceiveCachedMetadata(data, dataLength);
}

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

  m_loader->clientAdapterDone();

  releaseClient()->didFinishLoading(finishTime);
  // |this| may be dead here.
}

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

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

void WebAssociatedURLLoaderImpl::ClientAdapter::notifyError(TimerBase* timer) {
  DCHECK_EQ(timer, &m_errorTimer);

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

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

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

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

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

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

  WebAssociatedURLLoaderImpl* m_parent;
};

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

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

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

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

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

void WebAssociatedURLLoaderImpl::loadAsynchronously(
    const WebURLRequest& request,
    WebAssociatedURLLoaderClient* 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);
    // TODO(yhirano): Remove this CHECK once https://crbug.com/667254 is fixed.
    CHECK(!m_loader);
    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 WebAssociatedURLLoaderImpl::cancel() {
  disposeObserver();
  cancelLoader();
  releaseClient();
}

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

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

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

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

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

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

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

  if (!m_client)
    return;

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

void WebAssociatedURLLoaderImpl::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.
  CHECK(ThreadState::current());

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

}  // namespace blink