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// 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.
#include "chrome/browser/metrics/metrics_state_manager.h"
#include "base/command_line.h"
#include "base/guid.h"
#include "base/metrics/histogram.h"
#include "base/metrics/sparse_histogram.h"
#include "base/prefs/pref_registry_simple.h"
#include "base/prefs/pref_service.h"
#include "base/rand_util.h"
#include "base/strings/string_number_conversions.h"
#include "base/time/time.h"
#include "chrome/browser/metrics/cloned_install_detector.h"
#include "chrome/browser/metrics/machine_id_provider.h"
#include "chrome/common/chrome_switches.h"
#include "chrome/common/metrics/caching_permuted_entropy_provider.h"
#include "chrome/common/pref_names.h"
#if defined(OS_CHROMEOS)
#include "chrome/browser/chromeos/settings/cros_settings.h"
#endif
namespace metrics {
namespace {
// The argument used to generate a non-identifying entropy source. We want no
// more than 13 bits of entropy, so use this max to return a number in the range
// [0, 7999] as the entropy source (12.97 bits of entropy).
const int kMaxLowEntropySize = 8000;
// Default prefs value for prefs::kMetricsLowEntropySource to indicate that the
// value has not yet been set.
const int kLowEntropySourceNotSet = -1;
// Generates a new non-identifying entropy source used to seed persistent
// activities.
int GenerateLowEntropySource() {
return base::RandInt(0, kMaxLowEntropySize - 1);
}
} // namespace
// static
bool MetricsStateManager::instance_exists_ = false;
MetricsStateManager::MetricsStateManager(PrefService* local_state)
: local_state_(local_state),
low_entropy_source_(kLowEntropySourceNotSet),
entropy_source_returned_(ENTROPY_SOURCE_NONE) {
ResetMetricsIDsIfNecessary();
if (IsMetricsReportingEnabled())
ForceClientIdCreation();
DCHECK(!instance_exists_);
instance_exists_ = true;
}
MetricsStateManager::~MetricsStateManager() {
DCHECK(instance_exists_);
instance_exists_ = false;
}
bool MetricsStateManager::IsMetricsReportingEnabled() {
// If the user permits metrics reporting with the checkbox in the
// prefs, we turn on recording. We disable metrics completely for
// non-official builds. This can be forced with a flag.
const CommandLine* command_line = CommandLine::ForCurrentProcess();
if (command_line->HasSwitch(switches::kEnableMetricsReportingForTesting))
return true;
// Disable metrics reporting when field trials are forced.
if (command_line->HasSwitch(switches::kForceFieldTrials))
return false;
bool enabled = false;
#if defined(GOOGLE_CHROME_BUILD)
#if defined(OS_CHROMEOS)
chromeos::CrosSettings::Get()->GetBoolean(chromeos::kStatsReportingPref,
&enabled);
#else
enabled = local_state_->GetBoolean(prefs::kMetricsReportingEnabled);
#endif // #if defined(OS_CHROMEOS)
#endif // defined(GOOGLE_CHROME_BUILD)
return enabled;
}
void MetricsStateManager::ForceClientIdCreation() {
if (!client_id_.empty())
return;
client_id_ = local_state_->GetString(prefs::kMetricsClientID);
if (!client_id_.empty())
return;
client_id_ = base::GenerateGUID();
local_state_->SetString(prefs::kMetricsClientID, client_id_);
if (local_state_->GetString(prefs::kMetricsOldClientID).empty()) {
// Record the timestamp of when the user opted in to UMA.
local_state_->SetInt64(prefs::kMetricsReportingEnabledTimestamp,
base::Time::Now().ToTimeT());
} else {
UMA_HISTOGRAM_BOOLEAN("UMA.ClientIdMigrated", true);
}
local_state_->ClearPref(prefs::kMetricsOldClientID);
}
void MetricsStateManager::CheckForClonedInstall() {
DCHECK(!cloned_install_detector_);
MachineIdProvider* provider = MachineIdProvider::CreateInstance();
if (!provider)
return;
cloned_install_detector_.reset(new ClonedInstallDetector(provider));
cloned_install_detector_->CheckForClonedInstall(local_state_);
}
scoped_ptr<const base::FieldTrial::EntropyProvider>
MetricsStateManager::CreateEntropyProvider() {
// For metrics reporting-enabled users, we combine the client ID and low
// entropy source to get the final entropy source. Otherwise, only use the low
// entropy source.
// This has two useful properties:
// 1) It makes the entropy source less identifiable for parties that do not
// know the low entropy source.
// 2) It makes the final entropy source resettable.
const int low_entropy_source_value = GetLowEntropySource();
UMA_HISTOGRAM_SPARSE_SLOWLY("UMA.LowEntropySourceValue",
low_entropy_source_value);
if (IsMetricsReportingEnabled()) {
if (entropy_source_returned_ == ENTROPY_SOURCE_NONE)
entropy_source_returned_ = ENTROPY_SOURCE_HIGH;
DCHECK_EQ(ENTROPY_SOURCE_HIGH, entropy_source_returned_);
const std::string high_entropy_source =
client_id_ + base::IntToString(low_entropy_source_value);
return scoped_ptr<const base::FieldTrial::EntropyProvider>(
new SHA1EntropyProvider(high_entropy_source));
}
if (entropy_source_returned_ == ENTROPY_SOURCE_NONE)
entropy_source_returned_ = ENTROPY_SOURCE_LOW;
DCHECK_EQ(ENTROPY_SOURCE_LOW, entropy_source_returned_);
#if defined(OS_ANDROID) || defined(OS_IOS)
return scoped_ptr<const base::FieldTrial::EntropyProvider>(
new CachingPermutedEntropyProvider(local_state_,
low_entropy_source_value,
kMaxLowEntropySize));
#else
return scoped_ptr<const base::FieldTrial::EntropyProvider>(
new PermutedEntropyProvider(low_entropy_source_value,
kMaxLowEntropySize));
#endif
}
// static
scoped_ptr<MetricsStateManager> MetricsStateManager::Create(
PrefService* local_state) {
scoped_ptr<MetricsStateManager> result;
// Note: |instance_exists_| is updated in the constructor and destructor.
if (!instance_exists_)
result.reset(new MetricsStateManager(local_state));
return result.Pass();
}
// static
void MetricsStateManager::RegisterPrefs(PrefRegistrySimple* registry) {
registry->RegisterBooleanPref(prefs::kMetricsResetIds, false);
registry->RegisterStringPref(prefs::kMetricsClientID, std::string());
registry->RegisterInt64Pref(prefs::kMetricsReportingEnabledTimestamp, 0);
registry->RegisterIntegerPref(prefs::kMetricsLowEntropySource,
kLowEntropySourceNotSet);
ClonedInstallDetector::RegisterPrefs(registry);
CachingPermutedEntropyProvider::RegisterPrefs(registry);
// TODO(asvitkine): Remove these once a couple of releases have passed.
// http://crbug.com/357704
registry->RegisterStringPref(prefs::kMetricsOldClientID, std::string());
registry->RegisterIntegerPref(prefs::kMetricsOldLowEntropySource, 0);
}
int MetricsStateManager::GetLowEntropySource() {
// Note that the default value for the low entropy source and the default pref
// value are both kLowEntropySourceNotSet, which is used to identify if the
// value has been set or not.
if (low_entropy_source_ != kLowEntropySourceNotSet)
return low_entropy_source_;
const CommandLine* command_line(CommandLine::ForCurrentProcess());
// Only try to load the value from prefs if the user did not request a reset.
// Otherwise, skip to generating a new value.
if (!command_line->HasSwitch(switches::kResetVariationState)) {
int value = local_state_->GetInteger(prefs::kMetricsLowEntropySource);
// If the value is outside the [0, kMaxLowEntropySize) range, re-generate
// it below.
if (value >= 0 && value < kMaxLowEntropySize) {
low_entropy_source_ = value;
UMA_HISTOGRAM_BOOLEAN("UMA.GeneratedLowEntropySource", false);
return low_entropy_source_;
}
}
UMA_HISTOGRAM_BOOLEAN("UMA.GeneratedLowEntropySource", true);
low_entropy_source_ = GenerateLowEntropySource();
local_state_->SetInteger(prefs::kMetricsLowEntropySource,
low_entropy_source_);
local_state_->ClearPref(prefs::kMetricsOldLowEntropySource);
metrics::CachingPermutedEntropyProvider::ClearCache(local_state_);
return low_entropy_source_;
}
void MetricsStateManager::ResetMetricsIDsIfNecessary() {
if (!local_state_->GetBoolean(prefs::kMetricsResetIds))
return;
UMA_HISTOGRAM_BOOLEAN("UMA.MetricsIDsReset", true);
DCHECK(client_id_.empty());
DCHECK_EQ(kLowEntropySourceNotSet, low_entropy_source_);
local_state_->ClearPref(prefs::kMetricsClientID);
local_state_->ClearPref(prefs::kMetricsLowEntropySource);
local_state_->ClearPref(prefs::kMetricsResetIds);
}
} // namespace metrics
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