blob: 9baa790918b4168ced4ce75d7341c0b1266a5ece [file] [log] [blame]
// 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 "components/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 "components/metrics/cloned_install_detector.h"
#include "components/metrics/machine_id_provider.h"
#include "components/metrics/metrics_pref_names.h"
#include "components/metrics/metrics_switches.h"
#include "components/variations/caching_permuted_entropy_provider.h"
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,
const base::Callback<bool(void)>& is_reporting_enabled_callback,
const StoreClientInfoCallback& store_client_info,
const LoadClientInfoCallback& retrieve_client_info)
: local_state_(local_state),
is_reporting_enabled_callback_(is_reporting_enabled_callback),
store_client_info_(store_client_info),
load_client_info_(retrieve_client_info),
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() {
return is_reporting_enabled_callback_.Run();
}
void MetricsStateManager::ForceClientIdCreation() {
if (!client_id_.empty())
return;
client_id_ = local_state_->GetString(prefs::kMetricsClientID);
if (!client_id_.empty()) {
// It is technically sufficient to only save a backup of the client id when
// it is initially generated below, but since the backup was only introduced
// in M38, seed it explicitly from here for some time.
BackUpCurrentClientInfo();
return;
}
const scoped_ptr<ClientInfo> client_info_backup =
LoadClientInfoAndMaybeMigrate();
if (client_info_backup) {
client_id_ = client_info_backup->client_id;
const base::Time now = base::Time::Now();
// Save the recovered client id and also try to reinstantiate the backup
// values for the dates corresponding with that client id in order to avoid
// weird scenarios where we could report an old client id with a recent
// install date.
local_state_->SetString(prefs::kMetricsClientID, client_id_);
local_state_->SetInt64(prefs::kInstallDate,
client_info_backup->installation_date != 0
? client_info_backup->installation_date
: now.ToTimeT());
local_state_->SetInt64(prefs::kMetricsReportingEnabledTimestamp,
client_info_backup->reporting_enabled_date != 0
? client_info_backup->reporting_enabled_date
: now.ToTimeT());
base::TimeDelta recovered_installation_age;
if (client_info_backup->installation_date != 0) {
recovered_installation_age =
now - base::Time::FromTimeT(client_info_backup->installation_date);
}
UMA_HISTOGRAM_COUNTS_10000("UMA.ClientIdBackupRecoveredWithAge",
recovered_installation_age.InHours());
// Flush the backup back to persistent storage in case we re-generated
// missing data above.
BackUpCurrentClientInfo();
return;
}
// Failing attempts at getting an existing client ID, generate a new one.
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);
BackUpCurrentClientInfo();
}
void MetricsStateManager::CheckForClonedInstall(
scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
DCHECK(!cloned_install_detector_);
MachineIdProvider* provider = MachineIdProvider::CreateInstance();
if (!provider)
return;
cloned_install_detector_.reset(new ClonedInstallDetector(provider));
cloned_install_detector_->CheckForClonedInstall(local_state_, task_runner);
}
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;
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;
#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,
const base::Callback<bool(void)>& is_reporting_enabled_callback,
const StoreClientInfoCallback& store_client_info,
const LoadClientInfoCallback& retrieve_client_info) {
scoped_ptr<MetricsStateManager> result;
// Note: |instance_exists_| is updated in the constructor and destructor.
if (!instance_exists_) {
result.reset(new MetricsStateManager(local_state,
is_reporting_enabled_callback,
store_client_info,
retrieve_client_info));
}
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);
}
void MetricsStateManager::BackUpCurrentClientInfo() {
ClientInfo client_info;
client_info.client_id = client_id_;
client_info.installation_date = local_state_->GetInt64(prefs::kInstallDate);
client_info.reporting_enabled_date =
local_state_->GetInt64(prefs::kMetricsReportingEnabledTimestamp);
store_client_info_.Run(client_info);
}
scoped_ptr<ClientInfo> MetricsStateManager::LoadClientInfoAndMaybeMigrate() {
scoped_ptr<metrics::ClientInfo> client_info = load_client_info_.Run();
// Prior to 2014-07, the client ID was stripped of its dashes before being
// saved. Migrate back to a proper GUID if this is the case. This migration
// code can be removed in M41+.
const size_t kGUIDLengthWithoutDashes = 32U;
if (client_info &&
client_info->client_id.length() == kGUIDLengthWithoutDashes) {
DCHECK(client_info->client_id.find('-') == std::string::npos);
std::string client_id_with_dashes;
client_id_with_dashes.reserve(kGUIDLengthWithoutDashes + 4U);
std::string::const_iterator client_id_it = client_info->client_id.begin();
for (size_t i = 0; i < kGUIDLengthWithoutDashes + 4U; ++i) {
if (i == 8U || i == 13U || i == 18U || i == 23U) {
client_id_with_dashes.push_back('-');
} else {
client_id_with_dashes.push_back(*client_id_it);
++client_id_it;
}
}
DCHECK(client_id_it == client_info->client_id.end());
client_info->client_id.assign(client_id_with_dashes);
}
// The GUID retrieved (and possibly fixed above) should be valid unless
// retrieval failed.
DCHECK(!client_info || base::IsValidGUID(client_info->client_id));
return client_info.Pass();
}
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);
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);
// Also clear the backed up client info.
store_client_info_.Run(ClientInfo());
}
} // namespace metrics