1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef EXTENSIONS_BROWSER_CONTENT_HASH_FETCHER_H_
6#define EXTENSIONS_BROWSER_CONTENT_HASH_FETCHER_H_
7
8#include <set>
9#include <string>
10
11#include "base/callback.h"
12#include "base/files/file_path.h"
13#include "base/memory/weak_ptr.h"
14#include "base/scoped_observer.h"
15#include "extensions/browser/content_verifier_delegate.h"
16#include "extensions/browser/extension_registry_observer.h"
17#include "extensions/common/extension.h"
18
19namespace content {
20class BrowserContext;
21}
22
23namespace extensions {
24
25class ExtensionRegistry;
26class ContentHashFetcherJob;
27
28// This class is responsible for getting signed expected hashes for use in
29// extension content verification. As extensions are loaded it will fetch and
30// parse/validate/cache this data as needed, including calculating expected
31// hashes for each block of each file within an extension. (These unsigned leaf
32// node block level hashes will always be checked at time of use use to make
33// sure they match the signed treehash root hash).
34class ContentHashFetcher : public ExtensionRegistryObserver {
35 public:
36  // A callback for when a fetch is complete. This reports back:
37  // -extension id
38  // -whether we were successful or not (have verified_contents.json and
39  // -computed_hashes.json files)
40  // -was it a forced check?
41  // -a set of paths whose contents didn't match expected values
42  typedef base::Callback<
43      void(const std::string&, bool, bool, const std::set<base::FilePath>&)>
44      FetchCallback;
45
46  // The consumer of this class needs to ensure that context and delegate
47  // outlive this object.
48  ContentHashFetcher(content::BrowserContext* context,
49                     ContentVerifierDelegate* delegate,
50                     const FetchCallback& callback);
51  virtual ~ContentHashFetcher();
52
53  // Begins the process of trying to fetch any needed verified contents, and
54  // listening for extension load/unload.
55  void Start();
56
57  // Explicitly ask to fetch hashes for |extension|. If |force| is true,
58  // we will always check the validity of the verified_contents.json and
59  // re-check the contents of the files in the filesystem.
60  void DoFetch(const Extension* extension, bool force);
61
62  // ExtensionRegistryObserver interface
63  virtual void OnExtensionLoaded(content::BrowserContext* browser_context,
64                                 const Extension* extension) OVERRIDE;
65  virtual void OnExtensionUnloaded(
66      content::BrowserContext* browser_context,
67      const Extension* extension,
68      UnloadedExtensionInfo::Reason reason) OVERRIDE;
69
70 private:
71  // Callback for when a job getting content hashes has completed.
72  void JobFinished(ContentHashFetcherJob* job);
73
74  content::BrowserContext* context_;
75  ContentVerifierDelegate* delegate_;
76  FetchCallback fetch_callback_;
77
78  // We keep around pointers to in-progress jobs, both so we can avoid
79  // scheduling duplicate work if fetching is already in progress, and so that
80  // we can cancel in-progress work at shutdown time.
81  typedef std::pair<ExtensionId, std::string> IdAndVersion;
82  typedef std::map<IdAndVersion, scoped_refptr<ContentHashFetcherJob> > JobMap;
83  JobMap jobs_;
84
85  // For observing the ExtensionRegistry.
86  ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver> observer_;
87
88  // Used for binding callbacks passed to jobs.
89  base::WeakPtrFactory<ContentHashFetcher> weak_ptr_factory_;
90
91  DISALLOW_COPY_AND_ASSIGN(ContentHashFetcher);
92};
93
94}  // namespace extensions
95
96#endif  // EXTENSIONS_BROWSER_CONTENT_HASH_FETCHER_H_
97