public async Task DiscoverDevicesAsync(Func <HttpDiscoveredDeviceContext, Task <bool> > onDeviceDiscovered, CancellationToken cancellationToken = default(CancellationToken))
{
string discoverRequest =
"M-SEARCH * HTTP/1.1\n" +
"Host: 239.255.255.250:1900\n" +
"Man: \"ssdp:discover\"\n" +
"ST: roku:ecp\n" +
"";
var bytes = Encoding.UTF8.GetBytes(discoverRequest);
using (var udpClient = new UdpClient(endPoint)) {
await udpClient.SendAsync(bytes, bytes.Length, "239.255.255.250", 1900).ConfigureAwait(false);
while (!cancellationToken.IsCancellationRequested)
{
var receiveTask = Task.Run(
async() => {
try {
return(await udpClient.ReceiveAsync().ConfigureAwait(false));
} catch (ObjectDisposedException) {
// NOTE: We assume that a disposal exception is an attempt to cancel an
// outstanding ReceiveAsync() by closing the socket (disposing the
// UdpClient).
throw new OperationCanceledException();
}
});
var cancellationTask = Task.Delay(TimeSpan.FromMilliseconds(-1), cancellationToken);
var completedTask = await Task.WhenAny(receiveTask, cancellationTask).ConfigureAwait(false);
if (completedTask == cancellationTask)
{
// NOTE: We allow the OperationCanceledException to bubble up, causing disposal of the
// UdpClient which would force any pending ReceiveAsync() to throw an
// ObjectDisposedException.
await cancellationTask.ConfigureAwait(false);
return;
}
var rawResponse = await receiveTask.ConfigureAwait(false);
var response = await ParseResponseAsync(rawResponse.Buffer).ConfigureAwait(false);
if (response.StatusCode == 200 &&
response.Headers.TryGetValue("ST", out string stHeader) &&
stHeader == "roku:ecp" &&
response.Headers.TryGetValue("LOCATION", out string location) &&
Uri.TryCreate(location, UriKind.Absolute, out Uri locationUri) &&
response.Headers.TryGetValue("USN", out string usn))
{
var serialNumber = usn.StartsWith("uuid:roku:ecp:")
? usn.Substring("uuid:roku:ecp:".Length)
: usn;
var device = new HttpRokuDevice(serialNumber, locationUri, this.handler);
bool cancelDiscovery = false;
var context = new HttpDiscoveredDeviceContext(device, serialNumber);
if (onDeviceDiscovered != null)
{
cancelDiscovery = await onDeviceDiscovered(context).ConfigureAwait(false);
}
var args = new HttpDeviceDiscoveredEventArgs(context)
{
CancelDiscovery = cancelDiscovery
};
this.DeviceDiscovered?.Invoke(this, args);
cancelDiscovery = args.CancelDiscovery;
var baseArgs = new DeviceDiscoveredEventArgs(context)
{
CancelDiscovery = cancelDiscovery
};
this.baseDeviceDiscovered?.Invoke(this, baseArgs);
cancelDiscovery = baseArgs.CancelDiscovery;
if (cancelDiscovery)
{
return;
}
}
}
}
}
public HttpDeviceDiscoveredEventArgs(HttpDiscoveredDeviceContext context)
: base(context)
{
this.Context = context;
}