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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/safe_browsing/content/browser/triggers/ad_sampler_trigger.h"
#include <string>
#include "base/feature_list.h"
#include "base/functional/bind.h"
#include "base/memory/ptr_util.h"
#include "base/metrics/field_trial_params.h"
#include "base/metrics/histogram_macros.h"
#include "base/rand_util.h"
#include "base/strings/string_number_conversions.h"
#include "base/task/sequenced_task_runner.h"
#include "components/safe_browsing/content/browser/content_unsafe_resource_util.h"
#include "components/safe_browsing/content/browser/triggers/trigger_manager.h"
#include "components/safe_browsing/content/browser/triggers/trigger_throttler.h"
#include "components/safe_browsing/content/browser/triggers/trigger_util.h"
#include "components/safe_browsing/content/browser/web_contents_key.h"
#include "components/safe_browsing/core/browser/referrer_chain_provider.h"
#include "components/safe_browsing/core/common/features.h"
#include "components/security_interstitials/core/unsafe_resource.h"
#include "components/security_interstitials/core/unsafe_resource_locator.h"
#include "content/public/browser/browser_task_traits.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/global_routing_id.h"
#include "content/public/browser/navigation_handle.h"
#include "content/public/browser/render_frame_host.h"
#include "content/public/browser/render_process_host.h"
#include "content/public/browser/web_contents.h"
#include "services/network/public/cpp/shared_url_loader_factory.h"
#include "services/network/public/cpp/simple_url_loader.h"
namespace safe_browsing {
// Param name of the denominator for controlling sampling frequency.
const char kAdSamplerFrequencyDenominatorParam[] =
"safe_browsing_ad_sampler_frequency_denominator";
// Default frequency denominator for the ad sampler.
const size_t kAdSamplerDefaultFrequency = 1000;
// A frequency denominator with this value indicates sampling is disabled.
const size_t kAdSamplerFrequencyDisabled = 0;
// Number of milliseconds to allow data collection to run before sending a
// report (since this trigger runs in the background).
const int64_t kAdSampleCollectionPeriodMilliseconds = 5000;
// Range of number of milliseconds to wait after a page finished loading before
// starting a report. Allows ads which load in the background to finish loading.
const int64_t kMaxAdSampleCollectionStartDelayMilliseconds = 5000;
const int64_t kMinAdSampleCollectionStartDelayMilliseconds = 500;
// Metric for tracking what the Ad Sampler trigger does on each navigation.
const char kAdSamplerTriggerActionMetricName[] =
"SafeBrowsing.Triggers.AdSampler.Action";
namespace {
size_t GetSamplerFrequencyDenominator() {
if (!base::FeatureList::IsEnabled(kAdSamplerTriggerFeature))
return kAdSamplerDefaultFrequency;
const std::string sampler_frequency_denominator =
base::GetFieldTrialParamValueByFeature(
kAdSamplerTriggerFeature, kAdSamplerFrequencyDenominatorParam);
int result;
if (!base::StringToInt(sampler_frequency_denominator, &result))
return kAdSamplerDefaultFrequency;
return result;
}
bool ShouldSampleAd(const size_t frequency_denominator) {
return frequency_denominator != kAdSamplerFrequencyDisabled &&
(base::RandUint64() % frequency_denominator) == 0;
}
} // namespace
AdSamplerTrigger::AdSamplerTrigger(
content::WebContents* web_contents,
TriggerManager* trigger_manager,
PrefService* prefs,
scoped_refptr<network::SharedURLLoaderFactory> url_loader_factory,
history::HistoryService* history_service,
ReferrerChainProvider* referrer_chain_provider)
: content::WebContentsObserver(web_contents),
content::WebContentsUserData<AdSamplerTrigger>(*web_contents),
sampler_frequency_denominator_(GetSamplerFrequencyDenominator()),
start_report_delay_ms_(
base::RandInt(kMinAdSampleCollectionStartDelayMilliseconds,
kMaxAdSampleCollectionStartDelayMilliseconds)),
finish_report_delay_ms_(kAdSampleCollectionPeriodMilliseconds),
trigger_manager_(trigger_manager),
prefs_(prefs),
url_loader_factory_(url_loader_factory),
history_service_(history_service),
referrer_chain_provider_(referrer_chain_provider),
task_runner_(content::GetUIThreadTaskRunner({})) {}
AdSamplerTrigger::~AdSamplerTrigger() = default;
void AdSamplerTrigger::DidFinishLoad(
content::RenderFrameHost* render_frame_host,
const GURL& validated_url) {
UMA_HISTOGRAM_ENUMERATION(kAdSamplerTriggerActionMetricName, TRIGGER_CHECK,
MAX_ACTIONS);
// We are using light-weight ad detection logic here so it's safe to do the
// check on each navigation for the sake of metrics.
if (!DetectGoogleAd(render_frame_host, validated_url)) {
UMA_HISTOGRAM_ENUMERATION(kAdSamplerTriggerActionMetricName,
NO_SAMPLE_NO_AD, MAX_ACTIONS);
return;
}
if (!ShouldSampleAd(sampler_frequency_denominator_)) {
UMA_HISTOGRAM_ENUMERATION(kAdSamplerTriggerActionMetricName,
NO_SAMPLE_AD_SKIPPED_FOR_FREQUENCY, MAX_ACTIONS);
return;
}
// Create a report after a short delay. The delay gives more time for ads to
// finish loading in the background. This is best-effort.
task_runner_->PostDelayedTask(
FROM_HERE,
base::BindOnce(&AdSamplerTrigger::CreateAdSampleReport,
weak_ptr_factory_.GetWeakPtr()),
base::Milliseconds(start_report_delay_ms_));
}
void AdSamplerTrigger::CreateAdSampleReport() {
TriggerManager::DataCollectionPermissions permissions =
TriggerManager::GetDataCollectionPermissions(*prefs_, web_contents());
auto* primary_main_frame = web_contents()->GetPrimaryMainFrame();
const content::GlobalRenderFrameHostId primary_main_frame_id =
primary_main_frame->GetGlobalId();
security_interstitials::UnsafeResource resource;
resource.threat_type = SBThreatType::SB_THREAT_TYPE_AD_SAMPLE;
resource.url = web_contents()->GetURL();
resource.rfh_locator =
security_interstitials::UnsafeResourceLocator::CreateForRenderFrameToken(
primary_main_frame_id.child_id,
primary_main_frame->GetFrameToken().value());
if (!trigger_manager_->StartCollectingThreatDetails(
TriggerType::AD_SAMPLE, web_contents(), resource, url_loader_factory_,
history_service_, referrer_chain_provider_, permissions)) {
UMA_HISTOGRAM_ENUMERATION(kAdSamplerTriggerActionMetricName,
NO_SAMPLE_COULD_NOT_START_REPORT, MAX_ACTIONS);
return;
}
// Call into TriggerManager to finish the reports after a short delay. Any
// ads that are detected during this delay will be rejected by TriggerManager
// because a report is already being collected, so we won't send multiple
// reports for the same page.
task_runner_->PostDelayedTask(
FROM_HERE,
base::BindOnce(
IgnoreResult(&TriggerManager::FinishCollectingThreatDetails),
base::Unretained(trigger_manager_), TriggerType::AD_SAMPLE,
GetWebContentsKey(web_contents()), base::TimeDelta(),
/*did_proceed=*/false, /*num_visits=*/0, permissions,
/*warning_shown_ts=*/std::nullopt,
/*is_hats_candidate=*/false),
base::Milliseconds(finish_report_delay_ms_));
UMA_HISTOGRAM_ENUMERATION(kAdSamplerTriggerActionMetricName, AD_SAMPLED,
MAX_ACTIONS);
}
size_t AdSamplerTrigger::GetSamplerFrequencyDenominatorForTest() {
return GetSamplerFrequencyDenominator();
}
void AdSamplerTrigger::SetSamplerFrequencyForTest(size_t denominator) {
sampler_frequency_denominator_ = denominator;
}
void AdSamplerTrigger::SetTaskRunnerForTest(
scoped_refptr<base::SequencedTaskRunner> task_runner) {
task_runner_ = task_runner;
}
WEB_CONTENTS_USER_DATA_KEY_IMPL(AdSamplerTrigger);
} // namespace safe_browsing
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