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      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 "extensions/common/extension.h"
     15 
     16 namespace content {
     17 class BrowserContext;
     18 }
     19 
     20 namespace extensions {
     21 
     22 class ExtensionRegistry;
     23 class ContentHashFetcherJob;
     24 class ContentVerifierDelegate;
     25 
     26 // This class is responsible for getting signed expected hashes for use in
     27 // extension content verification. As extensions are loaded it will fetch and
     28 // parse/validate/cache this data as needed, including calculating expected
     29 // hashes for each block of each file within an extension. (These unsigned leaf
     30 // node block level hashes will always be checked at time of use use to make
     31 // sure they match the signed treehash root hash).
     32 class ContentHashFetcher {
     33  public:
     34   // A callback for when a fetch is complete. This reports back:
     35   // -extension id
     36   // -whether we were successful or not (have verified_contents.json and
     37   // -computed_hashes.json files)
     38   // -was it a forced check?
     39   // -a set of paths whose contents didn't match expected values
     40   typedef base::Callback<
     41       void(const std::string&, bool, bool, const std::set<base::FilePath>&)>
     42       FetchCallback;
     43 
     44   // The consumer of this class needs to ensure that context and delegate
     45   // outlive this object.
     46   ContentHashFetcher(content::BrowserContext* context,
     47                      ContentVerifierDelegate* delegate,
     48                      const FetchCallback& callback);
     49   virtual ~ContentHashFetcher();
     50 
     51   // Explicitly ask to fetch hashes for |extension|. If |force| is true,
     52   // we will always check the validity of the verified_contents.json and
     53   // re-check the contents of the files in the filesystem.
     54   void DoFetch(const Extension* extension, bool force);
     55 
     56   // These should be called when an extension is loaded or unloaded.
     57   virtual void ExtensionLoaded(const Extension* extension);
     58   virtual void ExtensionUnloaded(const Extension* extension);
     59 
     60  private:
     61   // Callback for when a job getting content hashes has completed.
     62   void JobFinished(ContentHashFetcherJob* job);
     63 
     64   content::BrowserContext* context_;
     65   ContentVerifierDelegate* delegate_;
     66   FetchCallback fetch_callback_;
     67 
     68   // We keep around pointers to in-progress jobs, both so we can avoid
     69   // scheduling duplicate work if fetching is already in progress, and so that
     70   // we can cancel in-progress work at shutdown time.
     71   typedef std::pair<ExtensionId, std::string> IdAndVersion;
     72   typedef std::map<IdAndVersion, scoped_refptr<ContentHashFetcherJob> > JobMap;
     73   JobMap jobs_;
     74 
     75   // Used for binding callbacks passed to jobs.
     76   base::WeakPtrFactory<ContentHashFetcher> weak_ptr_factory_;
     77 
     78   DISALLOW_COPY_AND_ASSIGN(ContentHashFetcher);
     79 };
     80 
     81 }  // namespace extensions
     82 
     83 #endif  // EXTENSIONS_BROWSER_CONTENT_HASH_FETCHER_H_
     84