protected virtual void CheckKeepalive(IPAddress ip, ServiceEntry svc)
{
if (KeepalivePing)
{
Ping ping = new Ping();
var result = ping.Send(ip, (int)KeepaliveTimeout * 1000);
if (result.Status != IPStatus.Success)
{
Debug.WriteLine("Removed service {0} at {1} due to keepalive ping failure", svc.Service, svc.Host);
RemoveService(svc);
return;
}
}
if (KeepaliveTcp)
{
using (var sock = new KeepaliveSocket(ip, svc.Port))
{
bool tcpConnected = sock.CanConnect((int)KeepaliveTimeout * 1000);
if (!tcpConnected)
{
Debug.WriteLine("Removed service {0} at {1}:{2} due to Tcp Connect failure", svc.Service, svc.Host, svc.Port);
RemoveService(svc);
return;
}
}
}
// Service is alive
svc.LastSeenAlive = DateTime.Now;
HostUpdated?.Invoke(this, svc);
}
public virtual void Init()
{
if (_disposedValue)
{
throw new ObjectDisposedException("ServiceDirectory");
}
_mdns.NetworkInterfaceDiscovered += (s, e) =>
{
// Ask for the name of all services.
_sd.QueryAllServices();
};
_sd.ServiceDiscovered += (s, serviceName) =>
{
// Check if this is a service we're interested in
bool interesting = true;
if (FilterFunction != null)
{
interesting = FilterFunction(serviceName.ToString());
}
if (!interesting)
{
return;
}
// Ask for the name of instances of the service.
_mdns.SendQuery(serviceName, type: DnsType.PTR);
};
_sd.ServiceInstanceDiscovered += (s, e) =>
{
// Ask for the service instance details.
_mdns.SendQuery(e.ServiceInstanceName, type: DnsType.SRV);
};
_sd.ServiceInstanceShutdown += (s, e) =>
{
Debug.WriteLine("Removing service instance {0} from MDNS message", e.ServiceInstanceName);
RemoveServiceByName(e.ServiceInstanceName.ToString());
};
_mdns.AnswerReceived += (s, e) =>
{
// Is this an answer to a service instance details?
var servers = e.Message.Answers.OfType <SRVRecord>();
foreach (var server in servers)
{
// For some reason, some services slip through the cracks of the first filter at ServiceDiscovered
// and we have to filter again.
bool interesting = true;
if (FilterFunction != null)
{
interesting = FilterFunction(server.Name.ToString());
}
if (!interesting)
{
continue;
}
var newSvc = new ServiceEntry
{
Host = server.Target.ToString(),
Port = server.Port,
Service = server.Name.ToString()
};
AddService(newSvc);
// Query IP addresses (only IPv4)
_mdns.SendQuery(server.Target, type: DnsType.A);
}
// Is this an answer to host addresses?
var addresses = e.Message.Answers.OfType <AddressRecord>();
foreach (var address in addresses)
{
// Find corresponding host
lock (_entries)
{
var host = from entry in _entries where entry.Host == address.Name select entry;
foreach (var h in host)
{
if (!h.IPAddresses.Contains(address.Address))
{
h.IPAddresses.Add(address.Address);
}
HostUpdated?.Invoke(this, h);
}
}
}
};
_mdns.Start();
ScheduleKeepAliveCheck();
}
