| // Copyright (c) 2012 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/variations/variations_http_header_provider.h" |
| |
| #include <vector> |
| |
| #include "base/base64.h" |
| #include "base/memory/singleton.h" |
| #include "base/metrics/histogram.h" |
| #include "base/strings/string_number_conversions.h" |
| #include "base/strings/string_split.h" |
| #include "base/strings/string_util.h" |
| #include "chrome/browser/google/google_util.h" |
| #include "chrome/common/metrics/proto/chrome_experiments.pb.h" |
| #include "net/base/registry_controlled_domains/registry_controlled_domain.h" |
| #include "net/http/http_request_headers.h" |
| #include "url/gurl.h" |
| |
| namespace chrome_variations { |
| |
| VariationsHttpHeaderProvider* VariationsHttpHeaderProvider::GetInstance() { |
| return Singleton<VariationsHttpHeaderProvider>::get(); |
| } |
| |
| void VariationsHttpHeaderProvider::AppendHeaders( |
| const GURL& url, |
| bool incognito, |
| bool uma_enabled, |
| net::HttpRequestHeaders* headers) { |
| // Note the criteria for attaching Chrome experiment headers: |
| // 1. We only transmit to *.google.<TLD> or *.youtube.<TLD> domains. |
| // 2. Only transmit for non-Incognito profiles. |
| // 3. For the X-Chrome-UMA-Enabled bit, only set it if UMA is in fact enabled |
| // for this install of Chrome. |
| // 4. For the X-Chrome-Variations, only include non-empty variation IDs. |
| if (incognito || !ShouldAppendHeaders(url)) |
| return; |
| |
| if (uma_enabled) |
| headers->SetHeaderIfMissing("X-Chrome-UMA-Enabled", "1"); |
| |
| // Lazily initialize the header, if not already done, before attempting to |
| // transmit it. |
| InitVariationIDsCacheIfNeeded(); |
| |
| std::string variation_ids_header_copy; |
| { |
| base::AutoLock scoped_lock(lock_); |
| variation_ids_header_copy = variation_ids_header_; |
| } |
| |
| if (!variation_ids_header_copy.empty()) { |
| headers->SetHeaderIfMissing("X-Chrome-Variations", |
| variation_ids_header_copy); |
| } |
| } |
| |
| bool VariationsHttpHeaderProvider::SetDefaultVariationIds( |
| const std::string& variation_ids) { |
| default_variation_ids_set_.clear(); |
| std::vector<std::string> entries; |
| base::SplitString(variation_ids, ',', &entries); |
| for (std::vector<std::string>::const_iterator it = entries.begin(); |
| it != entries.end(); ++it) { |
| int variation_id = 0; |
| if (!base::StringToInt(*it, &variation_id)) { |
| default_variation_ids_set_.clear(); |
| return false; |
| } |
| default_variation_ids_set_.insert(variation_id); |
| } |
| return true; |
| } |
| |
| VariationsHttpHeaderProvider::VariationsHttpHeaderProvider() |
| : variation_ids_cache_initialized_(false) { |
| } |
| |
| VariationsHttpHeaderProvider::~VariationsHttpHeaderProvider() { |
| } |
| |
| void VariationsHttpHeaderProvider::OnFieldTrialGroupFinalized( |
| const std::string& trial_name, |
| const std::string& group_name) { |
| VariationID new_id = |
| GetGoogleVariationID(GOOGLE_WEB_PROPERTIES, trial_name, group_name); |
| if (new_id == EMPTY_ID) |
| return; |
| |
| base::AutoLock scoped_lock(lock_); |
| variation_ids_set_.insert(new_id); |
| UpdateVariationIDsHeaderValue(); |
| } |
| |
| void VariationsHttpHeaderProvider::InitVariationIDsCacheIfNeeded() { |
| base::AutoLock scoped_lock(lock_); |
| if (variation_ids_cache_initialized_) |
| return; |
| |
| // Register for additional cache updates. This is done first to avoid a race |
| // that could cause registered FieldTrials to be missed. |
| DCHECK(base::MessageLoop::current()); |
| base::FieldTrialList::AddObserver(this); |
| |
| base::TimeTicks before_time = base::TimeTicks::Now(); |
| |
| base::FieldTrial::ActiveGroups initial_groups; |
| base::FieldTrialList::GetActiveFieldTrialGroups(&initial_groups); |
| for (base::FieldTrial::ActiveGroups::const_iterator it = |
| initial_groups.begin(); |
| it != initial_groups.end(); ++it) { |
| const VariationID id = |
| GetGoogleVariationID(GOOGLE_WEB_PROPERTIES, it->trial_name, |
| it->group_name); |
| if (id != EMPTY_ID) |
| variation_ids_set_.insert(id); |
| } |
| UpdateVariationIDsHeaderValue(); |
| |
| UMA_HISTOGRAM_CUSTOM_COUNTS( |
| "Variations.HeaderConstructionTime", |
| (base::TimeTicks::Now() - before_time).InMicroseconds(), |
| 0, |
| base::TimeDelta::FromSeconds(1).InMicroseconds(), |
| 50); |
| |
| variation_ids_cache_initialized_ = true; |
| } |
| |
| void VariationsHttpHeaderProvider::UpdateVariationIDsHeaderValue() { |
| lock_.AssertAcquired(); |
| |
| // The header value is a serialized protobuffer of Variation IDs which is |
| // base64 encoded before transmitting as a string. |
| variation_ids_header_.clear(); |
| |
| if (variation_ids_set_.empty() && default_variation_ids_set_.empty()) |
| return; |
| |
| // This is the bottleneck for the creation of the header, so validate the size |
| // here. Force a hard maximum on the ID count in case the Variations server |
| // returns too many IDs and DOSs receiving servers with large requests. |
| DCHECK_LE(variation_ids_set_.size(), 10U); |
| if (variation_ids_set_.size() > 20) |
| return; |
| |
| // Merge the two sets of experiment ids. |
| std::set<VariationID> all_variation_ids_set = default_variation_ids_set_; |
| for (std::set<VariationID>::const_iterator it = variation_ids_set_.begin(); |
| it != variation_ids_set_.end(); ++it) { |
| all_variation_ids_set.insert(*it); |
| } |
| metrics::ChromeVariations proto; |
| for (std::set<VariationID>::const_iterator it = all_variation_ids_set.begin(); |
| it != all_variation_ids_set.end(); ++it) { |
| proto.add_variation_id(*it); |
| } |
| |
| std::string serialized; |
| proto.SerializeToString(&serialized); |
| |
| std::string hashed; |
| if (base::Base64Encode(serialized, &hashed)) { |
| // If successful, swap the header value with the new one. |
| // Note that the list of IDs and the header could be temporarily out of sync |
| // if IDs are added as the header is recreated. The receiving servers are OK |
| // with such discrepancies. |
| variation_ids_header_ = hashed; |
| } else { |
| NOTREACHED() << "Failed to base64 encode Variation IDs value: " |
| << serialized; |
| } |
| } |
| |
| // static |
| bool VariationsHttpHeaderProvider::ShouldAppendHeaders(const GURL& url) { |
| if (google_util::IsGoogleDomainUrl(url, google_util::ALLOW_SUBDOMAIN, |
| google_util::ALLOW_NON_STANDARD_PORTS)) { |
| return true; |
| } |
| |
| // The below mirrors logic in IsGoogleDomainUrl(), but for youtube.<TLD>. |
| if (!url.is_valid() || !url.SchemeIsHTTPOrHTTPS()) |
| return false; |
| |
| const std::string host = url.host(); |
| const size_t tld_length = net::registry_controlled_domains::GetRegistryLength( |
| host, |
| net::registry_controlled_domains::EXCLUDE_UNKNOWN_REGISTRIES, |
| net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES); |
| if ((tld_length == 0) || (tld_length == std::string::npos)) |
| return false; |
| |
| const std::string host_minus_tld(host, 0, host.length() - tld_length); |
| return LowerCaseEqualsASCII(host_minus_tld, "youtube.") || |
| EndsWith(host_minus_tld, ".youtube.", false); |
| } |
| |
| } // namespace chrome_variations |