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content / browser / reduce_accept_language / reduce_accept_language_utils.cc [blame]
// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/reduce_accept_language/reduce_accept_language_utils.h"
#include <optional>
#include "base/strings/string_util.h"
#include "content/browser/renderer_host/frame_tree.h"
#include "content/browser/renderer_host/frame_tree_node.h"
#include "content/public/browser/browser_context.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/web_contents.h"
#include "net/http/http_util.h"
#include "services/network/public/cpp/features.h"
#include "url/origin.h"
namespace content {
namespace {
std::string GetFirstUserAcceptLanguage(
const std::vector<std::string>& user_accept_language) {
DCHECK(user_accept_language.size() > 0);
// Return the first user's accept-language. User accept language shouldn't be
// empty since we read from language prefs. If it's empty, we need to catch up
// this case to known any major issue.
return user_accept_language[0];
}
} // namespace
ReduceAcceptLanguageUtils::PersistLanguageResult::PersistLanguageResult() =
default;
ReduceAcceptLanguageUtils::PersistLanguageResult::PersistLanguageResult(
const PersistLanguageResult& other) = default;
ReduceAcceptLanguageUtils::PersistLanguageResult::~PersistLanguageResult() =
default;
ReduceAcceptLanguageUtils::ReduceAcceptLanguageUtils(
ReduceAcceptLanguageControllerDelegate& delegate)
: delegate_(delegate) {}
ReduceAcceptLanguageUtils::~ReduceAcceptLanguageUtils() = default;
// static
std::optional<ReduceAcceptLanguageUtils> ReduceAcceptLanguageUtils::Create(
BrowserContext* browser_context) {
DCHECK(browser_context);
if (!base::FeatureList::IsEnabled(network::features::kReduceAcceptLanguage)) {
return std::nullopt;
}
ReduceAcceptLanguageControllerDelegate* reduce_accept_lang_delegate =
browser_context->GetReduceAcceptLanguageControllerDelegate();
if (!reduce_accept_lang_delegate)
return std::nullopt;
return std::make_optional<ReduceAcceptLanguageUtils>(
*reduce_accept_lang_delegate);
}
// static
bool ReduceAcceptLanguageUtils::DoesAcceptLanguageMatchContentLanguage(
const std::string& accept_language,
const std::string& content_language) {
return content_language == "*" ||
base::EqualsCaseInsensitiveASCII(accept_language, content_language) ||
// Check whether `accept-language` has the same base language with
// `content-language`, e.g. Accept-Language: en-US will be considered a
// match for Content-Language: en.
(base::StartsWith(accept_language, content_language,
base::CompareCase::INSENSITIVE_ASCII) &&
accept_language[content_language.size()] == '-');
}
// static
bool ReduceAcceptLanguageUtils::OriginCanReduceAcceptLanguage(
const url::Origin& request_origin) {
return request_origin.GetURL().SchemeIsHTTPOrHTTPS();
}
// static
bool ReduceAcceptLanguageUtils::CheckDisableReduceAcceptLanguageOriginTrial(
const GURL& request_url,
FrameTreeNode* frame_tree_node,
OriginTrialsControllerDelegate* origin_trials_delegate) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
if (!origin_trials_delegate || !frame_tree_node) {
return false;
}
url::Origin request_origin = url::Origin::Create(request_url);
std::optional<url::Origin> partition_origin =
GetOriginForLanguageLookup(request_origin, frame_tree_node);
if (request_origin.opaque() || !partition_origin.has_value() ||
partition_origin.value().opaque()) {
return false;
}
return origin_trials_delegate->IsFeaturePersistedForOrigin(
request_origin, partition_origin.value(),
blink::mojom::OriginTrialFeature::kDisableReduceAcceptLanguage,
base::Time::Now());
}
std::optional<std::string>
ReduceAcceptLanguageUtils::GetFirstMatchPreferredLanguage(
const std::vector<std::string>& preferred_languages,
const std::vector<std::string>& available_languages) {
// Match the language in priority order.
for (const auto& preferred_language : preferred_languages) {
for (const auto& available_language : available_languages) {
if (available_language == "*" ||
base::EqualsCaseInsensitiveASCII(preferred_language,
available_language)) {
return preferred_language;
}
}
}
// If the site's available languages don't match any of the user's preferred
// languages, then browser won't do anything further.
return std::nullopt;
}
std::optional<std::string>
ReduceAcceptLanguageUtils::AddNavigationRequestAcceptLanguageHeaders(
const url::Origin& request_origin,
FrameTreeNode* frame_tree_node,
net::HttpRequestHeaders* headers) {
DCHECK(headers);
std::optional<std::string> reduced_accept_language =
LookupReducedAcceptLanguage(request_origin, frame_tree_node);
if (reduced_accept_language) {
std::string expanded_language_list =
net::HttpUtil::ExpandLanguageList(reduced_accept_language.value());
headers->SetHeader(
net::HttpRequestHeaders::kAcceptLanguage,
net::HttpUtil::GenerateAcceptLanguageHeader(expanded_language_list));
}
return reduced_accept_language;
}
bool ReduceAcceptLanguageUtils::ReadAndPersistAcceptLanguageForNavigation(
const url::Origin& request_origin,
const net::HttpRequestHeaders& request_headers,
const network::mojom::ParsedHeadersPtr& parsed_headers) {
DCHECK_CURRENTLY_ON(BrowserThread::UI);
DCHECK(parsed_headers);
if (!parsed_headers->content_language || !parsed_headers->avail_language) {
return false;
}
if (!OriginCanReduceAcceptLanguage(request_origin))
return false;
// Skip when reading user's accept-language is empty since it's required when
// doing language negotiation.
if (delegate_->GetUserAcceptLanguages().empty()) {
return false;
}
std::optional<std::string> initial_accept_language =
request_headers.GetHeader(net::HttpRequestHeaders::kAcceptLanguage);
if (!initial_accept_language) {
// If we can't find Accept-Language in the request header, we directly
// return false since we expect we added the reduced Accept-Language when
// initializing the navigation request.
return false;
}
PersistLanguageResult persist_params = GetLanguageToPersist(
*initial_accept_language, parsed_headers->content_language.value(),
delegate_->GetUserAcceptLanguages(),
parsed_headers->avail_language.value());
if (persist_params.language_to_persist) {
delegate_->PersistReducedLanguage(
request_origin, persist_params.language_to_persist.value());
}
return persist_params.should_resend_request;
}
std::optional<std::string>
ReduceAcceptLanguageUtils::LookupReducedAcceptLanguage(
const url::Origin& request_origin,
FrameTreeNode* frame_tree_node) {
DCHECK(frame_tree_node);
if (!base::FeatureList::IsEnabled(network::features::kReduceAcceptLanguage) ||
!OriginCanReduceAcceptLanguage(request_origin)) {
return std::nullopt;
}
const std::vector<std::string>& user_accept_languages =
delegate_->GetUserAcceptLanguages();
// Early return when user's accept-language preference is empty.
if (user_accept_languages.empty()) {
return std::nullopt;
}
const std::optional<url::Origin>& origin_for_lookup =
GetOriginForLanguageLookup(request_origin, frame_tree_node);
const std::optional<std::string>& persisted_language =
origin_for_lookup
? delegate_->GetReducedLanguage(origin_for_lookup.value())
: std::nullopt;
// We should return user's first accept-language if the feature is enabled
// and no persist language was found in prefs service.
if (!persisted_language) {
return GetFirstUserAcceptLanguage(user_accept_languages);
}
// Use the preferred language stored by the delegate if it matches any of the
// user's current preferences.
auto iter = base::ranges::find_if(
user_accept_languages, [&](const std::string& language) {
return DoesAcceptLanguageMatchContentLanguage(
language, persisted_language.value());
});
if (iter != user_accept_languages.end()) {
return persisted_language;
}
// If the preferred language stored by the delegate doesn't match any of the
// user's currently preferred Accept-Languages, then the user might have
// changed their preferences since the result was stored. In this case, clear
// the persisted value and use the first Accept-Language instead.
delegate_->ClearReducedLanguage(origin_for_lookup.value());
return GetFirstUserAcceptLanguage(user_accept_languages);
}
std::optional<url::Origin>
ReduceAcceptLanguageUtils::GetOriginForLanguageLookup(
const url::Origin& request_origin,
FrameTreeNode* frame_tree_node) {
// See explanation in header file.
if (frame_tree_node->IsOutermostMainFrame()) {
return request_origin;
} else if (!frame_tree_node->IsInFencedFrameTree()) {
RenderFrameHostImpl* outermost_main_rfh =
frame_tree_node->frame_tree().GetMainFrame()->GetOutermostMainFrame();
return outermost_main_rfh->GetLastCommittedOrigin();
}
return std::nullopt;
}
void ReduceAcceptLanguageUtils::RemoveReducedAcceptLanguage(
const url::Origin& origin,
FrameTreeNode* frame_tree_node) {
// Skip if kReduceAcceptLanguage feature isn't enabled because deprecation
// origin trial is used to disable reduce accept-language.
if (!base::FeatureList::IsEnabled(network::features::kReduceAcceptLanguage)) {
return;
}
// Skip for opaque origins or the current frame isn't the outermost main
// frame.
if (origin.opaque() || !frame_tree_node->IsOutermostMainFrame()) {
return;
}
delegate_->ClearReducedLanguage(origin);
}
ReduceAcceptLanguageUtils::PersistLanguageResult
ReduceAcceptLanguageUtils::GetLanguageToPersist(
const std::string& initial_accept_language,
const std::vector<std::string>& content_languages,
const std::vector<std::string>& preferred_languages,
const std::vector<std::string>& available_languages) {
DCHECK(preferred_languages.size() > 0);
PersistLanguageResult result;
// If the response content-language matches the initial accept language
// values, no need to resend the request.
std::string selected_language;
if (base::ranges::any_of(content_languages, [&](const std::string& language) {
return ReduceAcceptLanguageUtils::
DoesAcceptLanguageMatchContentLanguage(initial_accept_language,
language);
})) {
selected_language = initial_accept_language;
} else {
// If content-language doesn't match initial accept-language and the site
// has available languages matching one of the the user's preferences, then
// the browser should resend the request with the top matching language.
const std::optional<std::string>& matched_language =
ReduceAcceptLanguageUtils::GetFirstMatchPreferredLanguage(
preferred_languages, available_languages);
if (matched_language) {
selected_language = matched_language.value();
// Only resend request if the `matched_language` doesn't match any
// content languages in current response header because otherwise
// resending the request won't get a better result.
result.should_resend_request = base::ranges::none_of(
content_languages, [&](const std::string& language) {
return base::EqualsCaseInsensitiveASCII(language,
matched_language.value());
});
}
}
// Only persist the language of choice for an origin if it differs from
// the user’s first preferred language because we can directly access the
// user’s first preferred language from language prefs.
if (!selected_language.empty() &&
selected_language != preferred_languages[0]) {
result.language_to_persist = selected_language;
}
return result;
}
} // namespace content