content/browser/preloading/prefetch/prefetch_streaming_url_loader.h

// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_PRELOADING_PREFETCH_PREFETCH_STREAMING_URL_LOADER_H_
#define CONTENT_BROWSER_PRELOADING_PREFETCH_PREFETCH_STREAMING_URL_LOADER_H_

#include "base/timer/timer.h"
#include "content/browser/loader/navigation_loader_interceptor.h"
#include "content/browser/preloading/prefetch/prefetch_streaming_url_loader_common_types.h"
#include "content/common/content_export.h"
#include "mojo/public/cpp/bindings/receiver.h"
#include "mojo/public/cpp/bindings/remote.h"
#include "services/network/public/mojom/url_loader.mojom.h"
#include "services/network/public/mojom/url_response_head.mojom-forward.h"

namespace network {
class SharedURLLoaderFactory;
}  // namespace network

namespace content {

class PrefetchResponseReader;
class ServiceWorkerMainResourceHandle;
class ServiceWorkerMainResourceLoaderInterceptor;

// `PrefetchStreamingURLLoader` is self-owned throughout its lifetime, and
// deleted asynchronously when `prefetch_url_loader_` is finished or canceled
// (e.g. on non-followed redirects or `CancelIfNotServing()`).
class CONTENT_EXPORT PrefetchStreamingURLLoader
    : public network::mojom::URLLoaderClient {
 public:
  // `network_url_loader_factory` is the URLLoaderFactory used for network
  // fetch. For SW-controlled prefetch, it can be:
  // - used asynchronously after ServiceWorker controller check is done, or
  // - unused if the request is intercepted by a ServiceWorker.
  //
  // `initial_service_worker_state`:
  // - For `PrefetchServiceWorkerState::kDisallowed`, perform non-SW-controlled
  //   prefetching (e.g. without checking
  //   `ServiceWorkerMainResourceLoaderInterceptor`).
  //   `browser_context_for_service_worker` can be null.
  // - For `PrefetchServiceWorkerState::kAllowed`, perform SW-controlled
  //   prefetching.
  //   `browser_context_for_service_worker` should be non-null for successful
  //   prefetch.
  static base::WeakPtr<PrefetchStreamingURLLoader> CreateAndStart(
      scoped_refptr<network::SharedURLLoaderFactory> network_url_loader_factory,
      const network::ResourceRequest& request,
      const net::NetworkTrafficAnnotationTag& network_traffic_annotation,
      base::TimeDelta timeout_duration,
      OnPrefetchResponseStartedCallback on_prefetch_response_started_callback,
      OnPrefetchRedirectCallback on_prefetch_redirect_callback,
      base::WeakPtr<PrefetchResponseReader> response_reader,
      PrefetchServiceWorkerState initial_service_worker_state,
      BrowserContext* browser_context_for_service_worker,
      OnServiceWorkerStateDeterminedCallback
          on_service_worker_state_determined_callback);

  // Must be called only from `CreateAndStart()`.
  PrefetchStreamingURLLoader(
      OnPrefetchResponseStartedCallback on_prefetch_response_started_callback,
      OnPrefetchRedirectCallback on_prefetch_redirect_callback,
      OnServiceWorkerStateDeterminedCallback
          on_service_worker_state_determined_callback);

  ~PrefetchStreamingURLLoader() override;

  PrefetchStreamingURLLoader(const PrefetchStreamingURLLoader&) = delete;
  PrefetchStreamingURLLoader& operator=(const PrefetchStreamingURLLoader&) =
      delete;

  void SetResponseReader(base::WeakPtr<PrefetchResponseReader> response_reader);

  // Informs the URL loader of how to handle the most recent redirect. This
  // should only be called after |on_prefetch_redirect_callback_| is called. The
  // value of |new_status| should only be one of the following:
  // - |kFollowRedirect|, if the redirect should be followed by |this|.
  // - |kStopSwitchInNetworkContextForRedirect|, if the redirect will be
  //   followed by a different |PrefetchStreamingURLLoader| due to a change in
  //   network context.
  // - |kFailedInvalidRedirect|, if the redirect should not be followed by
  //   |this|.
  void HandleRedirect(PrefetchRedirectStatus redirect_status,
                      const net::RedirectInfo& redirect_info,
                      network::mojom::URLResponseHeadPtr redirect_head);

  // Called from PrefetchResponseReader.
  void SetPriority(net::RequestPriority priority, int32_t intra_priority_value);

  base::WeakPtr<PrefetchStreamingURLLoader> GetWeakPtr() {
    return weak_ptr_factory_.GetWeakPtr();
  }

  void OnStartServing();

  // Cancels the prefetching and schedule deletion, if any of its corresponding
  // `PrefetchResponseReader` does NOT start serving. This can cancel the
  // prefetching prematurely and leave `this` and `PrefetchResponseReader`
  // stalled.
  // TODO(crbug.com/40064891): Consider cleaning up this behavior (== existing
  // behavior, previously as `ResetAllStreamingURLLoaders()`).
  void CancelIfNotServing();

  // Only for CHECK()ing.
  NOINLINE bool IsDeletionScheduledForCHECK() const;

  void SetOnDeletionScheduledForTests(
      base::OnceClosure on_deletion_scheduled_for_tests);

 private:
  void StartServiceWorkerInterceptor(
      BrowserContext* browser_context,
      scoped_refptr<network::SharedURLLoaderFactory> network_url_loader_factory,
      const network::ResourceRequest& request,
      const net::NetworkTrafficAnnotationTag& network_traffic_annotation,
      base::TimeDelta timeout_duration);
  void ServiceWorkerInterceptorLoaderCallback(
      scoped_refptr<network::SharedURLLoaderFactory> network_url_loader_factory,
      const network::ResourceRequest& request,
      const net::NetworkTrafficAnnotationTag& network_traffic_annotation,
      base::TimeDelta timeout_duration,
      std::optional<NavigationLoaderInterceptor::Result> interceptor_result);
  void Start(PrefetchServiceWorkerState final_service_worker_state,
             scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory,
             const network::ResourceRequest& request,
             const net::NetworkTrafficAnnotationTag& network_traffic_annotation,
             base::TimeDelta timeout_duration);

  // Disconnect prefetching URLLoader and schedule deletion of `this`.
  // Currently this itself doesn't mark `this` or corresponding
  // `PrefetchResponseReader` as failed.
  void DisconnectPrefetchURLLoaderMojo();

  // network::mojom::URLLoaderClient
  void OnReceiveEarlyHints(network::mojom::EarlyHintsPtr early_hints) override;
  void OnReceiveResponse(
      network::mojom::URLResponseHeadPtr head,
      mojo::ScopedDataPipeConsumerHandle body,
      std::optional<mojo_base::BigBuffer> cached_metadata) override;
  void OnReceiveRedirect(const net::RedirectInfo& redirect_info,
                         network::mojom::URLResponseHeadPtr head) override;
  void OnUploadProgress(int64_t current_position,
                        int64_t total_size,
                        OnUploadProgressCallback callback) override;
  void OnTransferSizeUpdated(int32_t transfer_size_diff) override;
  void OnComplete(
      const network::URLLoaderCompletionStatus& completion_status) override;

  std::unique_ptr<PrefetchStreamingURLLoader> self_pointer_;

  // The timer that triggers a timeout when a request takes too long.
  base::OneShotTimer timeout_timer_;

  // Set if any of corresponding `PrefetchResponseReader` starts serving.
  bool used_for_serving_{false};

  // Only true while awaiting a response from `PrefetchService` during
  // a redirect handring. Specifically, it becomes true when `OnReceiveRedirect`
  // is called and becomes false either after `HandleRedirect` is called from
  // `PrefetchService`, or `OnComplete` is received.
  bool is_waiting_handle_redirect_from_prefetch_service_{false};

  // The URL loader used to request the prefetch.
  mojo::Remote<network::mojom::URLLoader> prefetch_url_loader_;
  mojo::Receiver<network::mojom::URLLoaderClient>
      prefetch_url_loader_client_receiver_{this};

  // Callbacks used to inform the caller of specific events of the prefetch
  // request.
  OnPrefetchResponseStartedCallback on_prefetch_response_started_callback_;
  OnPrefetchRedirectCallback on_prefetch_redirect_callback_;

  // Called when deletion is scheduled. Only for testing corner cases around
  // deletion.
  base::OnceClosure on_deletion_scheduled_for_tests_;

  // Called just before URLLoaderFactory is started. At that time, ServiceWorker
  // interceptor (if any) is already done, and it's known whether there is a
  // ServiceWorker controller, indicated by `ServiceWorkerState`.
  OnServiceWorkerStateDeterminedCallback
      on_service_worker_state_determined_callback_;

  base::WeakPtr<PrefetchResponseReader> response_reader_;

  // Set/used only for SW-controlled prefetching.
  std::unique_ptr<ServiceWorkerMainResourceLoaderInterceptor> interceptor_;
  std::unique_ptr<ServiceWorkerMainResourceHandle> service_worker_handle_;

  base::WeakPtrFactory<PrefetchStreamingURLLoader> weak_ptr_factory_{this};
};

}  // namespace content

#endif  // CONTENT_BROWSER_PRELOADING_PREFETCH_PREFETCH_STREAMING_URL_LOADER_H_