chrome/browser/metrics/variations/variations_seed_store.h

   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 CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SEED_STORE_H_
   6 #define CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SEED_STORE_H_
   7
   8 #include <string>
   9
  10 #include "base/compiler_specific.h"
  11 #include "base/gtest_prod_util.h"
  12 #include "base/time/time.h"
  13
  14 class PrefService;
  15 class PrefRegistrySimple;
  16
  17 namespace variations {
  18 class VariationsSeed;
  19 }
  20
  21 namespace chrome_variations {
  22
  23 // VariationsSeedStore is a helper class for reading and writing the variations
  24 // seed from Local State.
  25 class VariationsSeedStore {
  26  public:
  27   explicit VariationsSeedStore(PrefService* local_state);
  28   virtual ~VariationsSeedStore();
  29
  30   // Loads the variations seed data from local state into |seed|. If there is a
  31   // problem with loading, the pref value is cleared and false is returned. If
  32   // successful, |seed| will contain the loaded data and true is returned.
  33   bool LoadSeed(variations::VariationsSeed* seed);
  34
  35   // Stores the given seed data (serialized protobuf data) to local state, along
  36   // with a base64-encoded digital signature for seed and the date when it was
  37   // fetched. The |seed_data| will be base64 encoded for storage. If the string
  38   // is invalid, the existing prefs are left as is and false is returned. On
  39   // success and if |parsed_seed| is not NULL, |parsed_seed| will be filled
  40   // with the de-serialized protobuf decoded from |seed_data|.
  41   bool StoreSeedData(const std::string& seed_data,
  42                      const std::string& base64_seed_signature,
  43                      const base::Time& date_fetched,
  44                      variations::VariationsSeed* parsed_seed);
  45
  46   // Updates |kVariationsSeedDate| and logs when previous date was from a
  47   // different day.
  48   void UpdateSeedDateAndLogDayChange(const base::Time& server_date_fetched);
  49
  50   // Returns the serial number of the last loaded or stored seed.
  51   const std::string& variations_serial_number() const {
  52     return variations_serial_number_;
  53   }
  54
  55   // Registers Local State prefs used by this class.
  56   static void RegisterPrefs(PrefRegistrySimple* registry);
  57
  58   // Returns the invalid signature in base64 format, or an empty string if the
  59   // signature was valid, missing, or if signature verification is disabled.
  60   std::string GetInvalidSignature() const;
  61
  62  protected:
  63   // Note: UMA histogram enum - don't re-order or remove entries.
  64   enum VerifySignatureResult {
  65     VARIATIONS_SEED_SIGNATURE_MISSING,
  66     VARIATIONS_SEED_SIGNATURE_DECODE_FAILED,
  67     VARIATIONS_SEED_SIGNATURE_INVALID_SIGNATURE,
  68     VARIATIONS_SEED_SIGNATURE_INVALID_SEED,
  69     VARIATIONS_SEED_SIGNATURE_VALID,
  70     VARIATIONS_SEED_SIGNATURE_ENUM_SIZE,
  71   };
  72
  73   // Verifies a variations seed (the serialized proto bytes) with the specified
  74   // base-64 encoded signature that was received from the server and returns the
  75   // result. The signature is assumed to be an "ECDSA with SHA-256" signature
  76   // (see kECDSAWithSHA256AlgorithmID in the .cc file). Returns the result of
  77   // signature verification or VARIATIONS_SEED_SIGNATURE_ENUM_SIZE if signature
  78   // verification is not enabled.
  79   virtual VariationsSeedStore::VerifySignatureResult VerifySeedSignature(
  80       const std::string& seed_bytes,
  81       const std::string& base64_seed_signature);
  82
  83  private:
  84   FRIEND_TEST_ALL_PREFIXES(VariationsSeedStoreTest, VerifySeedSignature);
  85
  86   // Clears all prefs related to variations seed storage.
  87   void ClearPrefs();
  88
  89   // Reads the variations seed data from prefs; returns true on success.
  90   bool ReadSeedData(std::string* seed_data);
  91
  92   // The pref service used to persist the variations seed.
  93   PrefService* local_state_;
  94
  95   // Cached serial number from the most recently fetched variations seed.
  96   std::string variations_serial_number_;
  97
  98   // Keeps track of an invalid signature.
  99   std::string invalid_base64_signature_;
 100
 101   DISALLOW_COPY_AND_ASSIGN(VariationsSeedStore);
 102 };
 103
 104 }  // namespace chrome_variations
 105
 106 #endif  // CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SEED_STORE_H_