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// Copyright 2019 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 "discovery/mdns/mdns_probe.h"
#include <utility>
#include "discovery/mdns/mdns_random.h"
#include "discovery/mdns/mdns_sender.h"
#include "discovery/mdns/public/mdns_constants.h"
#include "platform/api/task_runner.h"
#include "platform/api/time.h"
namespace openscreen {
namespace discovery {
MdnsProbe::MdnsProbe(DomainName target_name, IPAddress address)
: target_name_(std::move(target_name)),
address_(std::move(address)),
address_record_(CreateAddressRecord(target_name_, address_)) {}
MdnsProbe::~MdnsProbe() = default;
MdnsProbeImpl::Observer::~Observer() = default;
MdnsProbeImpl::MdnsProbeImpl(MdnsSender* sender,
MdnsReceiver* receiver,
MdnsRandom* random_delay,
TaskRunner* task_runner,
ClockNowFunctionPtr now_function,
Observer* observer,
DomainName target_name,
IPAddress address)
: MdnsProbe(std::move(target_name), std::move(address)),
random_delay_(random_delay),
task_runner_(task_runner),
now_function_(now_function),
alarm_(now_function_, task_runner_),
sender_(sender),
receiver_(receiver),
observer_(observer) {
OSP_DCHECK(sender_);
OSP_DCHECK(receiver_);
OSP_DCHECK(random_delay_);
OSP_DCHECK(task_runner_);
OSP_DCHECK(observer_);
receiver_->AddResponseCallback(this);
alarm_.ScheduleFromNow([this]() { ProbeOnce(); },
random_delay_->GetInitialProbeDelay());
}
MdnsProbeImpl::~MdnsProbeImpl() {
OSP_DCHECK(task_runner_->IsRunningOnTaskRunner());
Stop();
}
void MdnsProbeImpl::ProbeOnce() {
OSP_DCHECK(task_runner_->IsRunningOnTaskRunner());
if (successful_probe_queries_++ < kProbeIterationCountBeforeSuccess) {
// MdnsQuerier cannot be used, because probe queries cannot use the cache,
// so instead directly send the query through the MdnsSender.
MdnsMessage probe_query(CreateMessageId(), MessageType::Query);
MdnsQuestion probe_question(target_name(), DnsType::kANY, DnsClass::kIN,
ResponseType::kUnicast);
probe_query.AddQuestion(probe_question);
probe_query.AddAuthorityRecord(address_record());
sender_->SendMulticast(probe_query);
alarm_.ScheduleFromNow([this]() { ProbeOnce(); },
kDelayBetweenProbeQueries);
} else {
Stop();
observer_->OnProbeSuccess(this);
}
}
void MdnsProbeImpl::Stop() {
OSP_DCHECK(task_runner_->IsRunningOnTaskRunner());
if (is_running_) {
alarm_.Cancel();
receiver_->RemoveResponseCallback(this);
is_running_ = false;
}
}
void MdnsProbeImpl::Postpone(std::chrono::seconds delay) {
OSP_DCHECK(task_runner_->IsRunningOnTaskRunner());
successful_probe_queries_ = 0;
alarm_.Cancel();
alarm_.ScheduleFromNow([this]() { ProbeOnce(); }, Clock::to_duration(delay));
}
void MdnsProbeImpl::OnMessageReceived(const MdnsMessage& message) {
OSP_DCHECK(task_runner_->IsRunningOnTaskRunner());
OSP_DCHECK(message.type() == MessageType::Response);
for (const auto& record : message.answers()) {
if (record.name() == target_name()) {
Stop();
observer_->OnProbeFailure(this);
}
}
}
} // namespace discovery
} // namespace openscreen
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