public AtemDiscoveryService(int updatePeriod = 10000, bool debug = false)
{
_debug = debug;
_knownDevices = new Dictionary <string, AtemDeviceInfo>();
_mdns = new MulticastService();
_mdns.UseIpv4 = true;
_mdns.UseIpv6 = false;
_mdns.NetworkInterfaceDiscovered += (s, e) => SendQuery();
_mdns.AnswerReceived += (s, e) => AnswerReceived(e.Message);
_mdns.Start();
_updateTimer = new Timer(a => {
DateTime now = DateTime.Now;
lock (_knownDevices)
{
List <string> ids = _knownDevices.Keys.ToList();
foreach (string id in ids)
{
AtemDeviceInfo dev = _knownDevices[id];
// Remove if not seen in too long
if (dev != null && now.Subtract(dev.LastSeen).TotalMilliseconds > updatePeriod * 3)
{
_knownDevices.Remove(id);
OnDeviceLost?.Invoke(this, dev);
}
}
}
SendQuery();
}, null, updatePeriod, updatePeriod);
}
private void AnswerReceived(Message message)
{
List <PTRRecord> answers = message.Answers.Where(a => a.Name == AtemDeviceInfo.ServiceName).OfType <PTRRecord>().ToList();
PTRRecord answer = answers.FirstOrDefault();
if (answer == null)
{
return;
}
if (_debug && answers.Count != 1)
{
Console.WriteLine("Too many answers!");
}
List <ResourceRecord> records = message.AdditionalRecords;
SRVRecord srvRec = records.OfType <SRVRecord>().FirstOrDefault(r => r.Type == DnsType.SRV && r.Name == answer.DomainName);
if (srvRec == null)
{
if (_debug)
{
Console.WriteLine("Missing SRV record for " + answer.DomainName);
}
return;
}
AddressRecord aRec = records.OfType <AddressRecord>().FirstOrDefault(r => r.Type == DnsType.A && r.Name == srvRec.Target);
if (aRec == null)
{
if (_debug)
{
Console.WriteLine("Missing A record for " + answer.DomainName);
}
return;
}
TXTRecord txtRec = records.OfType <TXTRecord>().FirstOrDefault(r => r.Type == DnsType.TXT && r.Name == answer.DomainName);
List <string> strings = txtRec == null ? new List <string>() : txtRec.Strings;
string name = string.Join(".", answer.DomainName.Labels);
if (name.EndsWith(AtemDeviceInfo.ServiceName))
{
name = name.Substring(0, name.Length - AtemDeviceInfo.ServiceName.Length - 1);
}
var dev = new AtemDeviceInfo(name, srvRec.Target.ToString(), DateTime.Now, aRec.Address.ToString(), srvRec.Port, strings);
lock (_knownDevices) {
_knownDevices[dev.DeviceId] = dev;
}
OnDeviceSeen?.Invoke(this, dev);
}
