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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/dnssd/impl/querier_impl.h"
#include <string>
#include <vector>
#include "platform/api/logging.h"
namespace openscreen {
namespace discovery {
namespace {
static constexpr char kLocalDomain[] = "local";
} // namespace
QuerierImpl::QuerierImpl(MdnsService* mdns_querier)
: mdns_querier_(mdns_querier) {
OSP_DCHECK(mdns_querier_);
}
QuerierImpl::~QuerierImpl() = default;
void QuerierImpl::StartQuery(absl::string_view service, Callback* callback) {
OSP_DCHECK(callback);
ServiceKey key(service, kLocalDomain);
DnsQueryInfo query = GetPtrQueryInfo(key);
if (!IsQueryRunning(key)) {
callback_map_[key] = {};
StartDnsQuery(query);
} else {
const std::vector<InstanceKey> keys = GetMatchingInstances(key);
for (const auto& key : keys) {
auto it = received_records_.find(key);
if (it == received_records_.end()) {
continue;
}
ErrorOr<DnsSdInstanceRecord> record = it->second.CreateRecord();
if (record.is_value()) {
callback->OnInstanceCreated(record.value());
}
}
}
callback_map_[key].push_back(callback);
}
bool QuerierImpl::IsQueryRunning(absl::string_view service) const {
return IsQueryRunning(ServiceKey(service, kLocalDomain));
}
void QuerierImpl::StopQuery(absl::string_view service, Callback* callback) {
OSP_DCHECK(callback);
ServiceKey key(service, kLocalDomain);
DnsQueryInfo query = GetPtrQueryInfo(key);
auto callback_it = callback_map_.find(key);
if (callback_it == callback_map_.end()) {
return;
}
std::vector<Callback*>* callbacks = &callback_it->second;
const auto it = std::find(callbacks->begin(), callbacks->end(), callback);
if (it != callbacks->end()) {
callbacks->erase(it);
if (callbacks->empty()) {
EraseInstancesOf(key);
callback_map_.erase(callback_it);
StopDnsQuery(query);
}
}
}
void QuerierImpl::OnRecordChanged(const MdnsRecord& record,
RecordChangedEvent event) {
IsPtrRecord(record) ? HandlePtrRecordChange(record, event)
: HandleNonPtrRecordChange(record, event);
}
Error QuerierImpl::HandlePtrRecordChange(const MdnsRecord& record,
RecordChangedEvent event) {
if (!HasValidDnsRecordAddress(record)) {
// This means that the received record is malformed.
return Error::Code::kParameterInvalid;
}
InstanceKey key(record);
DnsQueryInfo query = GetInstanceQueryInfo(key);
switch (event) {
case RecordChangedEvent::kCreated:
StartDnsQuery(query);
return Error::None();
case RecordChangedEvent::kDeleted:
StopDnsQuery(query);
EraseInstancesOf(ServiceKey(key));
return Error::None();
case RecordChangedEvent::kUpdated:
return Error::Code::kOperationInvalid;
}
return Error::Code::kUnknownError;
}
Error QuerierImpl::HandleNonPtrRecordChange(const MdnsRecord& record,
RecordChangedEvent event) {
if (!HasValidDnsRecordAddress(record)) {
// This means that the call received had malformed data.
return Error::Code::kParameterInvalid;
}
const ServiceKey key(record);
if (!IsQueryRunning(key)) {
// This means that the call was already queued up on the TaskRunner when the
// callback was removed. The caller no longer cares, so drop the record.
return Error::Code::kOperationCancelled;
}
const std::vector<Callback*>& callbacks = callback_map_[key];
// Get the current InstanceRecord data associated with the received record.
const InstanceKey id(record);
ErrorOr<DnsSdInstanceRecord> old_instance_record = Error::Code::kItemNotFound;
auto it = received_records_.find(id);
if (it == received_records_.end()) {
it = received_records_.emplace(id, DnsData(id)).first;
} else {
old_instance_record = it->second.CreateRecord();
}
DnsData* data = &it->second;
// Apply the changes specified by the received event to the stored
// InstanceRecord.
Error apply_result = data->ApplyDataRecordChange(record, event);
if (!apply_result.ok()) {
OSP_LOG_ERROR << "Received erroneous record change. Error: "
<< apply_result;
return apply_result;
}
// Send an update to the user, based on how the new and old records compare.
ErrorOr<DnsSdInstanceRecord> new_instance_record = data->CreateRecord();
NotifyCallbacks(callbacks, old_instance_record, new_instance_record);
return Error::None();
}
void QuerierImpl::NotifyCallbacks(
const std::vector<Callback*>& callbacks,
const ErrorOr<DnsSdInstanceRecord>& old_record,
const ErrorOr<DnsSdInstanceRecord>& new_record) {
if (old_record.is_value() && new_record.is_value()) {
for (Callback* callback : callbacks) {
callback->OnInstanceUpdated(new_record.value());
}
} else if (old_record.is_value() && !new_record.is_value()) {
for (Callback* callback : callbacks) {
callback->OnInstanceDeleted(old_record.value());
}
} else if (!old_record.is_value() && new_record.is_value()) {
for (Callback* callback : callbacks) {
callback->OnInstanceCreated(new_record.value());
}
}
}
void QuerierImpl::EraseInstancesOf(const ServiceKey& key) {
std::vector<InstanceKey> keys = GetMatchingInstances(key);
const auto it = callback_map_.find(key);
std::vector<Callback*> callbacks;
if (it != callback_map_.end()) {
callbacks = it->second;
}
for (const auto& key : keys) {
auto recieved_record = received_records_.find(key);
if (recieved_record == received_records_.end()) {
continue;
}
ErrorOr<DnsSdInstanceRecord> instance_record =
recieved_record->second.CreateRecord();
if (instance_record.is_value()) {
for (Callback* callback : callbacks) {
callback->OnInstanceDeleted(instance_record.value());
}
}
received_records_.erase(recieved_record);
}
}
std::vector<InstanceKey> QuerierImpl::GetMatchingInstances(
const ServiceKey& key) {
// Because only one or two PTR queries are expected at a time, expect >=1/2 of
// the records to be associated with a given PTR. They can't be removed in
// less than O(n) time, so just iterate across them all.
std::vector<InstanceKey> keys;
for (auto it = received_records_.begin(); it != received_records_.end();
it++) {
if (it->first.IsInstanceOf(key)) {
keys.push_back(it->first);
}
}
return keys;
}
void QuerierImpl::StartDnsQuery(const DnsQueryInfo& query) {
mdns_querier_->StartQuery(query.name, query.dns_type, query.dns_class, this);
}
void QuerierImpl::StopDnsQuery(const DnsQueryInfo& query) {
mdns_querier_->StopQuery(query.name, query.dns_type, query.dns_class, this);
}
} // namespace discovery
} // namespace openscreen
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