chrome/browser/safe_browsing/download_protection/download_protection_delegate.h

// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_SAFE_BROWSING_DOWNLOAD_PROTECTION_DOWNLOAD_PROTECTION_DELEGATE_H_
#define CHROME_BROWSER_SAFE_BROWSING_DOWNLOAD_PROTECTION_DOWNLOAD_PROTECTION_DELEGATE_H_

#include <memory>
#include <vector>

#include "chrome/browser/safe_browsing/download_protection/download_protection_util.h"
#include "net/traffic_annotation/network_traffic_annotation.h"

class GURL;
class Profile;

namespace base {
class FilePath;
}

namespace content {
struct FileSystemAccessWriteItem;
}

namespace download {
class DownloadItem;
}

namespace network {
struct ResourceRequest;
}

namespace safe_browsing {

class ClientDownloadRequest;

// Interface providing platform-specific logic for Download Protection, used
// with DownloadProtectionService, CheckClientDownloadRequest, and
// DownloadRequestMaker.
class DownloadProtectionDelegate {
 public:
  // Creates the appropriate implementation instance.
  static std::unique_ptr<DownloadProtectionDelegate> CreateForPlatform();

  virtual ~DownloadProtectionDelegate() = default;

  // Returns whether the download URL should be checked based on user
  // preferences.
  virtual bool ShouldCheckDownloadUrl(download::DownloadItem* item) const = 0;

  // Returns whether the download item may be checked by CheckClientDownload().
  // This is based on user preferences, properties of the file, and potentially
  // random sampling.
  // A return value of false indicates that the delegate does not permit the
  // download to be checked.
  // A return value of true indicates that checking the download is permitted,
  // but caller may apply further logic to determine whether a check occurs.
  // TODO(chlily): Implementations of this method currently rely on the checks
  // in IsSupportedDownload. This is redundant. Refactor this logic to eliminate
  // IsSupportedDownload().
  virtual bool MayCheckClientDownload(download::DownloadItem* item) const = 0;

  // Returns whether the File System Access write may be checked by
  // CheckFileSystemAccessWrite().
  virtual bool MayCheckFileSystemAccessWrite(
      content::FileSystemAccessWriteItem* item) const = 0;

  // Returns enum value indicating whether the download item may be checked by
  // CheckClientDownload() based on whether the file supports the check.
  // TODO(chlily): Remove this method. The only place where it is called seems
  // to be vestigial, and does not affect whether CheckClientDownload ultimately
  // happens.
  virtual MayCheckDownloadResult IsSupportedDownload(
      download::DownloadItem& item,
      const base::FilePath& target_path) const = 0;

  // Called after the ClientDownloadRequest has been constructed, prior to
  // serializing the ClientDownloadRequest into a string to send in the POST
  // request body of the network request. Allows the delegate to request final
  // modifications to apply to the request, in the form of a vector of callbacks
  // to invoke, each of which will yield a modification to be made to
  // ClientDownloadRequest.
  //
  // `item` is the download this pertains to, which may be null, e.g. if this
  // request is not for a download. `profile` is the Profile associated with the
  // underlying item being checked (a DownloadItem or
  // FileSystemAccessWriteItem).
  virtual std::vector<PendingClientDownloadRequestModification>
  ProduceClientDownloadRequestModifications(const download::DownloadItem* item,
                                            Profile* profile);

  // Called immediately prior to consuming the ResourceRequest used to send out
  // a download ping. Allows the delegate to make final modifications to the
  // ResourceRequest. The delegate must add the appropriate Content-Type HTTP
  // header in this method.
  virtual void FinalizeResourceRequest(
      network::ResourceRequest& resource_request) = 0;

  // Returns the URL that will be contacted for download protection requests.
  virtual const GURL& GetDownloadRequestUrl() const = 0;

  // Sampling rate for when an allowlisted download may generate a sampled ping,
  // if other requirements are met.
  virtual float GetAllowlistedDownloadSampleRate() const = 0;

  // Sampling rate for when an unsupported download may generate a sampled ping,
  // if other requirements are met.
  virtual float GetUnsupportedFileSampleRate(
      const base::FilePath& filename) const = 0;

  // Completes the network traffic annotation for CheckClientDownloadRequest.
  virtual net::NetworkTrafficAnnotationTag
  CompleteClientDownloadRequestTrafficAnnotation(
      const net::PartialNetworkTrafficAnnotationTag& partial_traffic_annotation)
      const = 0;
};

}  // namespace safe_browsing

#endif  // CHROME_BROWSER_SAFE_BROWSING_DOWNLOAD_PROTECTION_DOWNLOAD_PROTECTION_DELEGATE_H_