chromium/content/browser/loader/keep_alive_url_loader.h

// Copyright 2023 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_LOADER_KEEP_ALIVE_URL_LOADER_H_
#define CONTENT_BROWSER_LOADER_KEEP_ALIVE_URL_LOADER_H_

#include <stdint.h>
#include <memory>
#include <queue>
#include <string>
#include <string_view>
#include <vector>

#include "base/functional/callback.h"
#include "base/functional/callback_helpers.h"
#include "base/memory/weak_ptr.h"
#include "base/timer/timer.h"
#include "base/types/pass_key.h"
#include "content/common/content_export.h"
#include "content/public/browser/weak_document_ptr.h"
#include "mojo/public/cpp/bindings/pending_remote.h"
#include "mojo/public/cpp/bindings/receiver.h"
#include "mojo/public/cpp/bindings/receiver_set.h"
#include "mojo/public/cpp/bindings/remote.h"
#include "net/traffic_annotation/network_traffic_annotation.h"
#include "services/network/public/cpp/resource_request.h"
#include "services/network/public/mojom/url_loader.mojom.h"
#include "services/network/public/mojom/url_response_head.mojom.h"
#include "third_party/blink/public/common/loader/throttling_url_loader.h"
#include "third_party/blink/public/mojom/loader/fetch_later.mojom.h"
#include "url/gurl.h"

namespace network {
class SharedURLLoaderFactory;
}

namespace blink {
class URLLoaderThrottle;
}

namespace content {

class BrowserContext;
class KeepAliveAttributionRequestHelper;
class KeepAliveURLBrowserTestBase;
class KeepAliveURLLoaderService;
class PolicyContainerHost;
class RenderFrameHostImpl;
class WeakDocumentPtr;

// A URLLoader for loading a fetch keepalive request via the browser process,
// including requests generated from the following JS API calls:
//   - fetch(..., {keepalive: true})
//   - navigator.sendBeacon(...)
//   - fetchLater(...)
//
// To load a keepalive request initiated by a renderer, this loader performs the
// following logic:
//
// 1. In ctor, stores request data sent from a renderer.
// 2. In `Start()`, asks the network service to start loading the request, and
//    then runs throttles to perform checks.
// 3. Handles request loading results from the network service, i.e. from the
//    remote of `url_loader_` (blink::ThrottlingURLLoader):
//    A. If it is `OnReceiveRedirect()`, this loader performs checks and runs
//       throttles, and then asks the network service to proceed with redirects
//       without interacting with renderer. The redirect params are stored for
//       later use.
//    B. If it is `OnReceiveResponse()` or `OnComplete()`, this loader does not
//       process response. Instead, it calls `ForwardURLLoad()` to begin to
//       forward previously saved mojom::URLLoaderClient calls to the renderer,
//       if the renderer is still alive; Otherwise, terminating this loader.
//    C. If a throttle asynchronously asks to cancel the request, similar to B,
//       the previously stored calls will be forwarded to the renderer.
//    D. The renderer's response to `ForwardURLLoad()` may be any of
//       mojom::URLLoader calls, in which they should continue forwarding by
//       calling `ForwardURLLoader()` again.
//
// See the "Longer Redirect Chain" section of the Design Doc for an example
// call sequence diagram.
//
// This class must only be constructed by `KeepAliveURLLoaderService`.
//
// The lifetime of an instance is roughly equal to the lifetime of a keepalive
// request, which may surpass the initiator renderer's lifetime.
//
// * Design Doc:
// https://docs.google.com/document/d/1ZzxMMBvpqn8VZBZKnb7Go8TWjnrGcXuLS_USwVVRUvY
// * Mojo Connections:
// https://docs.google.com/document/d/1RKPgoLBrrLZBPn01XtwHJiLlH9rA7nIRXQJIR7BUqJA/edit#heading=h.y1og20bzkuf7
class CONTENT_EXPORT KeepAliveURLLoader
    : public network::mojom::URLLoader,
      public blink::ThrottlingURLLoader::ClientReceiverDelegate,
      public blink::mojom::FetchLaterLoader { … };

}  // namespace content

#endif  // CONTENT_BROWSER_LOADER_KEEP_ALIVE_URL_LOADER_H_