| // Copyright 2012 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "net/dns/dns_config_service.h" |
| |
| #include <memory> |
| #include <optional> |
| #include <string> |
| |
| #include "base/check_op.h" |
| #include "base/files/file_path.h" |
| #include "base/functional/bind.h" |
| #include "base/location.h" |
| #include "base/logging.h" |
| #include "base/notreached.h" |
| #include "base/sequence_checker.h" |
| #include "base/task/sequenced_task_runner.h" |
| #include "base/threading/scoped_blocking_call.h" |
| #include "base/time/time.h" |
| #include "net/dns/dns_hosts.h" |
| #include "net/dns/serial_worker.h" |
| |
| namespace net { |
| |
| // static |
| const base::TimeDelta DnsConfigService::kInvalidationTimeout = |
| base::Milliseconds(150); |
| |
| DnsConfigService::DnsConfigService( |
| base::FilePath::StringPieceType hosts_file_path, |
| std::optional<base::TimeDelta> config_change_delay) |
| : config_change_delay_(config_change_delay), |
| hosts_file_path_(hosts_file_path) { |
| DETACH_FROM_SEQUENCE(sequence_checker_); |
| } |
| |
| DnsConfigService::~DnsConfigService() { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| if (hosts_reader_) |
| hosts_reader_->Cancel(); |
| } |
| |
| void DnsConfigService::ReadConfig(const CallbackType& callback) { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| DCHECK(!callback.is_null()); |
| DCHECK(callback_.is_null()); |
| callback_ = callback; |
| ReadConfigNow(); |
| ReadHostsNow(); |
| } |
| |
| void DnsConfigService::WatchConfig(const CallbackType& callback) { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| DCHECK(!callback.is_null()); |
| DCHECK(callback_.is_null()); |
| callback_ = callback; |
| watch_failed_ = !StartWatching(); |
| ReadConfigNow(); |
| ReadHostsNow(); |
| } |
| |
| void DnsConfigService::RefreshConfig() { |
| // Overridden on supported platforms. |
| NOTREACHED(); |
| } |
| |
| DnsConfigService::Watcher::Watcher(DnsConfigService& service) |
| : service_(&service) {} |
| |
| DnsConfigService::Watcher::~Watcher() { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| } |
| |
| void DnsConfigService::Watcher::OnConfigChanged(bool succeeded) { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| service_->OnConfigChanged(succeeded); |
| } |
| |
| void DnsConfigService::Watcher::OnHostsChanged(bool succeeded) { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| service_->OnHostsChanged(succeeded); |
| } |
| |
| void DnsConfigService::Watcher::CheckOnCorrectSequence() { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| } |
| |
| DnsConfigService::HostsReader::HostsReader( |
| base::FilePath::StringPieceType hosts_file_path, |
| DnsConfigService& service) |
| : service_(&service), hosts_file_path_(hosts_file_path) {} |
| |
| DnsConfigService::HostsReader::~HostsReader() = default; |
| |
| DnsConfigService::HostsReader::WorkItem::WorkItem( |
| std::unique_ptr<DnsHostsParser> dns_hosts_parser) |
| : dns_hosts_parser_(std::move(dns_hosts_parser)) { |
| DCHECK(dns_hosts_parser_); |
| } |
| |
| DnsConfigService::HostsReader::WorkItem::~WorkItem() = default; |
| |
| std::optional<DnsHosts> DnsConfigService::HostsReader::WorkItem::ReadHosts() { |
| base::ScopedBlockingCall scoped_blocking_call(FROM_HERE, |
| base::BlockingType::MAY_BLOCK); |
| DnsHosts dns_hosts; |
| if (!dns_hosts_parser_->ParseHosts(&dns_hosts)) |
| return std::nullopt; |
| |
| return dns_hosts; |
| } |
| |
| bool DnsConfigService::HostsReader::WorkItem::AddAdditionalHostsTo( |
| DnsHosts& in_out_dns_hosts) { |
| // Nothing to add in base implementation. |
| return true; |
| } |
| |
| void DnsConfigService::HostsReader::WorkItem::DoWork() { |
| hosts_ = ReadHosts(); |
| if (!hosts_.has_value()) |
| return; |
| |
| if (!AddAdditionalHostsTo(hosts_.value())) |
| hosts_.reset(); |
| } |
| |
| std::unique_ptr<SerialWorker::WorkItem> |
| DnsConfigService::HostsReader::CreateWorkItem() { |
| return std::make_unique<WorkItem>( |
| std::make_unique<DnsHostsFileParser>(hosts_file_path_)); |
| } |
| |
| bool DnsConfigService::HostsReader::OnWorkFinished( |
| std::unique_ptr<SerialWorker::WorkItem> serial_worker_work_item) { |
| DCHECK(serial_worker_work_item); |
| |
| WorkItem* work_item = static_cast<WorkItem*>(serial_worker_work_item.get()); |
| if (work_item->hosts_.has_value()) { |
| service_->OnHostsRead(std::move(work_item->hosts_).value()); |
| return true; |
| } else { |
| LOG(WARNING) << "Failed to read DnsHosts."; |
| return false; |
| } |
| } |
| |
| void DnsConfigService::ReadHostsNow() { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| |
| if (!hosts_reader_) { |
| DCHECK(!hosts_file_path_.empty()); |
| hosts_reader_ = |
| std::make_unique<HostsReader>(hosts_file_path_.value(), *this); |
| } |
| hosts_reader_->WorkNow(); |
| } |
| |
| void DnsConfigService::InvalidateConfig() { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| if (!have_config_) |
| return; |
| have_config_ = false; |
| StartTimer(); |
| } |
| |
| void DnsConfigService::InvalidateHosts() { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| if (!have_hosts_) |
| return; |
| have_hosts_ = false; |
| StartTimer(); |
| } |
| |
| void DnsConfigService::OnConfigRead(DnsConfig config) { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| DCHECK(config.IsValid()); |
| |
| if (!config.EqualsIgnoreHosts(dns_config_)) { |
| dns_config_.CopyIgnoreHosts(config); |
| need_update_ = true; |
| } |
| |
| have_config_ = true; |
| if (have_hosts_ || watch_failed_) |
| OnCompleteConfig(); |
| } |
| |
| void DnsConfigService::OnHostsRead(DnsHosts hosts) { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| |
| if (hosts != dns_config_.hosts) { |
| dns_config_.hosts = std::move(hosts); |
| need_update_ = true; |
| } |
| |
| have_hosts_ = true; |
| if (have_config_ || watch_failed_) |
| OnCompleteConfig(); |
| } |
| |
| void DnsConfigService::StartTimer() { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| if (last_sent_empty_) { |
| DCHECK(!timer_.IsRunning()); |
| return; // No need to withdraw again. |
| } |
| timer_.Stop(); |
| |
| // Give it a short timeout to come up with a valid config. Otherwise withdraw |
| // the config from the receiver. The goal is to avoid perceivable network |
| // outage (when using the wrong config) but at the same time avoid |
| // unnecessary Job aborts in HostResolverImpl. The signals come from multiple |
| // sources so it might receive multiple events during a config change. |
| timer_.Start(FROM_HERE, kInvalidationTimeout, this, |
| &DnsConfigService::OnTimeout); |
| } |
| |
| void DnsConfigService::OnTimeout() { |
| DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_); |
| DCHECK(!last_sent_empty_); |
| // Indicate that even if there is no change in On*Read, we will need to |
| // update the receiver when the config becomes complete. |
| need_update_ = true; |
| // Empty config is considered invalid. |
| last_sent_empty_ = true; |
| callback_.Run(DnsConfig()); |
| } |
| |
| void DnsConfigService::OnCompleteConfig() { |
| timer_.AbandonAndStop(); |
| if (!need_update_) |
| return; |
| need_update_ = false; |
| last_sent_empty_ = false; |
| if (watch_failed_) { |
| // If a watch failed, the config may not be accurate, so report empty. |
| callback_.Run(DnsConfig()); |
| } else { |
| callback_.Run(dns_config_); |
| } |
| } |
| |
| void DnsConfigService::OnConfigChanged(bool succeeded) { |
| if (config_change_delay_) { |
| // Ignore transient flutter of config source by delaying the signal a bit. |
| base::SequencedTaskRunner::GetCurrentDefault()->PostDelayedTask( |
| FROM_HERE, |
| base::BindOnce(&DnsConfigService::OnConfigChangedDelayed, |
| weak_factory_.GetWeakPtr(), succeeded), |
| config_change_delay_.value()); |
| } else { |
| OnConfigChangedDelayed(succeeded); |
| } |
| } |
| |
| void DnsConfigService::OnHostsChanged(bool succeeded) { |
| InvalidateHosts(); |
| if (succeeded) { |
| ReadHostsNow(); |
| } else { |
| LOG(ERROR) << "DNS hosts watch failed."; |
| watch_failed_ = true; |
| } |
| } |
| |
| void DnsConfigService::OnConfigChangedDelayed(bool succeeded) { |
| InvalidateConfig(); |
| if (succeeded) { |
| ReadConfigNow(); |
| } else { |
| LOG(ERROR) << "DNS config watch failed."; |
| watch_failed_ = true; |
| } |
| } |
| |
| } // namespace net |