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
14class PrefService;
15class PrefRegistrySimple;
16
17namespace variations {
18class VariationsSeed;
19}
20
21namespace chrome_variations {
22
23// VariationsSeedStore is a helper class for reading and writing the variations
24// seed from Local State.
25class 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 protected:
59  // Note: UMA histogram enum - don't re-order or remove entries.
60  enum VerifySignatureResult {
61    VARIATIONS_SEED_SIGNATURE_MISSING,
62    VARIATIONS_SEED_SIGNATURE_DECODE_FAILED,
63    VARIATIONS_SEED_SIGNATURE_INVALID_SIGNATURE,
64    VARIATIONS_SEED_SIGNATURE_INVALID_SEED,
65    VARIATIONS_SEED_SIGNATURE_VALID,
66    VARIATIONS_SEED_SIGNATURE_ENUM_SIZE,
67  };
68
69  // Verifies a variations seed (the serialized proto bytes) with the specified
70  // base-64 encoded signature that was received from the server and returns the
71  // result. The signature is assumed to be an "ECDSA with SHA-256" signature
72  // (see kECDSAWithSHA256AlgorithmID in the .cc file). Returns the result of
73  // signature verification or VARIATIONS_SEED_SIGNATURE_ENUM_SIZE if signature
74  // verification is not enabled.
75  virtual VariationsSeedStore::VerifySignatureResult VerifySeedSignature(
76      const std::string& seed_bytes,
77      const std::string& base64_seed_signature);
78
79 private:
80  FRIEND_TEST_ALL_PREFIXES(VariationsSeedStoreTest, VerifySeedSignature);
81
82  // Clears all prefs related to variations seed storage.
83  void ClearPrefs();
84
85  // The pref service used to persist the variations seed.
86  PrefService* local_state_;
87
88  // Cached serial number from the most recently fetched variations seed.
89  std::string variations_serial_number_;
90
91  DISALLOW_COPY_AND_ASSIGN(VariationsSeedStore);
92};
93
94}  // namespace chrome_variations
95
96#endif  // CHROME_BROWSER_METRICS_VARIATIONS_VARIATIONS_SEED_STORE_H_
97