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// Copyright (c) 2015, the Dartino project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
import 'dart:async';
import 'dart:collection';
import 'package:multicast_dns/src/resource_record.dart';
/// Class for maintaining state about pending mDNS requests.
class PendingRequest extends LinkedListEntry<PendingRequest> {
/// Creates a new PendingRequest.
PendingRequest(this.type, this.domainName, this.controller);
/// The [ResourceRecordType] of the request.
final int type;
/// The domain name to look up via mDNS.
///
/// For example, `'_http._tcp.local` to look up HTTP services on the local
/// domain.
final String domainName;
/// A StreamController managing the request.
final StreamController<ResourceRecord> controller;
/// The timer for the request.
Timer timer;
}
/// Class for keeping track of pending lookups and processing incoming
/// query responses.
class LookupResolver {
final LinkedList<PendingRequest> _pendingRequests =
LinkedList<PendingRequest>();
/// Adds a request and returns a [Stream] of [ResourceRecord] responses.
Stream<T> addPendingRequest<T extends ResourceRecord>(
int type, String name, Duration timeout) {
final StreamController<T> controller = StreamController<T>();
final PendingRequest request = PendingRequest(type, name, controller);
final Timer timer = Timer(timeout, () {
request.unlink();
controller.close();
});
request.timer = timer;
_pendingRequests.add(request);
return controller.stream;
}
/// Parses [ResoureRecord]s received and delivers them to the appropriate
/// listener(s) added via [addPendingRequest].
void handleResponse(List<ResourceRecord> response) {
for (ResourceRecord r in response) {
final int type = r.resourceRecordType;
String name = r.name.toLowerCase();
if (name.endsWith('.')) {
name = name.substring(0, name.length - 1);
}
bool responseMatches(PendingRequest request) {
String requestName = request.domainName.toLowerCase();
// make, e.g. "_http" become "_http._tcp.local".
if (!requestName.endsWith('local')) {
if (!requestName.endsWith('._tcp.local') &&
!requestName.endsWith('._udp.local') &&
!requestName.endsWith('._tcp') &&
!requestName.endsWith('.udp')) {
requestName += '._tcp';
}
requestName += '.local';
}
return requestName == name && request.type == type;
}
for (PendingRequest pendingRequest in _pendingRequests) {
if (responseMatches(pendingRequest)) {
if (pendingRequest.controller.isClosed) {
return;
}
pendingRequest.controller.add(r);
}
}
}
}
/// Removes any pending requests and ends processing.
void clearPendingRequests() {
while (_pendingRequests.isNotEmpty) {
final PendingRequest request = _pendingRequests.first;
request.unlink();
request.timer.cancel();
request.controller.close();
}
}
}