| // Copyright 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef COMPONENTS_UPDATE_CLIENT_CRX_DOWNLOADER_H_ |
| #define COMPONENTS_UPDATE_CLIENT_CRX_DOWNLOADER_H_ |
| |
| #include <stdint.h> |
| |
| #include <memory> |
| #include <string> |
| #include <vector> |
| |
| #include "base/callback.h" |
| #include "base/files/file_path.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/sequence_checker.h" |
| #include "base/single_thread_task_runner.h" |
| #include "url/gurl.h" |
| |
| namespace update_client { |
| |
| // Defines a download interface for downloading components, with retrying on |
| // fallback urls in case of errors. This class implements a chain of |
| // responsibility design pattern. It can give successors in the chain a chance |
| // to handle a download request, until one of them succeeds, or there are no |
| // more urls or successors to try. A callback is always called at the end of |
| // the download, one time only. |
| // When multiple urls and downloaders exists, first all the urls are tried, in |
| // the order they are provided in the StartDownload function argument. After |
| // that, the download request is routed to the next downloader in the chain. |
| // The members of this class expect to be called from the main thread only. |
| class CrxDownloader : public base::RefCountedThreadSafe<CrxDownloader> { |
| public: |
| struct DownloadMetrics { |
| enum Downloader { kNone = 0, kUrlFetcher, kBits }; |
| |
| DownloadMetrics(); |
| |
| GURL url; |
| |
| Downloader downloader; |
| |
| int error; |
| |
| int64_t downloaded_bytes; // -1 means that the byte count is unknown. |
| int64_t total_bytes; |
| |
| uint64_t download_time_ms; |
| }; |
| |
| // Contains the progress or the outcome of the download. |
| struct Result { |
| // Download error: 0 indicates success. |
| int error = 0; |
| |
| // Path of the downloaded file if the download was successful. |
| base::FilePath response; |
| }; |
| |
| // The callback is posted only once, when the download is handled, regardless |
| // of how many urls have been tried, and how many successors in the chain of |
| // downloaders have handled the download. |
| using DownloadCallback = base::OnceCallback<void(const Result& result)>; |
| |
| // The callback may be posted when progress is made during a download. |
| // Since this class implements a chain of responsibility, the callback could |
| // be invoked for different urls and different downloaders, as progress is |
| // being made down the chain. |downloaded_bytes| and |total_bytes| contain the |
| // number of bytes downloaded up to this point, and the number of bytes to |
| // download (which is the size of the CRX). When the number of bytes is not |
| // known, the values are -1. |
| using ProgressCallback = |
| base::RepeatingCallback<void(int64_t downloaded_bytes, |
| int64_t total_bytes)>; |
| |
| CrxDownloader(const CrxDownloader&) = delete; |
| CrxDownloader& operator=(const CrxDownloader&) = delete; |
| |
| // Starts the download. One instance of the class handles one download only. |
| // One instance of CrxDownloader can only be started once, otherwise the |
| // behavior is undefined. The callback gets invoked if the download can't |
| // be started. |expected_hash| represents the SHA256 cryptographic hash of |
| // the download payload, represented as a hexadecimal string. |
| void StartDownloadFromUrl(const GURL& url, |
| const std::string& expected_hash, |
| DownloadCallback download_callback); |
| void StartDownload(const std::vector<GURL>& urls, |
| const std::string& expected_hash, |
| DownloadCallback download_callback); |
| |
| void set_progress_callback(const ProgressCallback& progress_callback); |
| |
| const std::vector<DownloadMetrics> download_metrics() const; |
| |
| protected: |
| explicit CrxDownloader(scoped_refptr<CrxDownloader> successor); |
| virtual ~CrxDownloader(); |
| |
| // Handles the fallback in the case of multiple urls and routing of the |
| // download to the following successor in the chain. Derived classes must call |
| // this function after each attempt at downloading the urls provided |
| // in the StartDownload function. |
| // In case of errors, |is_handled| indicates that a server side error has |
| // occured for the current url and the url should not be retried down |
| // the chain to avoid DDOS of the server. This url will be removed from the |
| // list of url and never tried again. |
| void OnDownloadComplete(bool is_handled, |
| const Result& result, |
| const DownloadMetrics& download_metrics); |
| |
| // Calls the callback when progress is made. |
| void OnDownloadProgress(int64_t downloaded_bytes, int64_t total_bytes); |
| |
| // Returns the url which is currently being downloaded from. |
| GURL url() const; |
| |
| scoped_refptr<base::SingleThreadTaskRunner> main_task_runner() const { |
| return main_task_runner_; |
| } |
| |
| private: |
| friend class base::RefCountedThreadSafe<CrxDownloader>; |
| |
| virtual void DoStartDownload(const GURL& url) = 0; |
| |
| void HandleDownloadError(bool is_handled, |
| const Result& result, |
| const DownloadMetrics& download_metrics); |
| |
| SEQUENCE_CHECKER(sequence_checker_); |
| |
| // Used to post callbacks to the main thread. |
| scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_; |
| |
| std::vector<GURL> urls_; |
| |
| // The SHA256 hash of the download payload in hexadecimal format. |
| std::string expected_hash_; |
| scoped_refptr<CrxDownloader> successor_; |
| DownloadCallback download_callback_; |
| ProgressCallback progress_callback_; |
| |
| std::vector<GURL>::iterator current_url_; |
| |
| std::vector<DownloadMetrics> download_metrics_; |
| }; |
| |
| } // namespace update_client |
| |
| #endif // COMPONENTS_UPDATE_CLIENT_CRX_DOWNLOADER_H_ |