/// <summary>
/// Send an announce request for this InfoHash.
/// </summary>
/// <param name="infoHash"></param>
/// <returns></returns>
public Task Announce(InfoHash infoHash)
{
lock (PendingAnnounces) {
PendingAnnounces.Enqueue(infoHash);
if (!ProcessingAnnounces)
{
ProcessingAnnounces = true;
ProcessQueue();
}
}
return(Task.CompletedTask);
}
async void ProcessQueue()
{
// Ensure this doesn't run on the UI thread as the networking calls can do some (partially) blocking operations.
// Specifically 'NetworkInterface.GetAllNetworkInterfaces' is synchronous and can take hundreds of milliseconds.
await MainLoop.SwitchToThreadpool();
await RateLimiterTask;
using var sendingClient = new UdpClient();
var nics = NetworkInterface.GetAllNetworkInterfaces();
while (true)
{
InfoHash infoHash = null;
lock (PendingAnnounces) {
if (PendingAnnounces.Count == 0)
{
// Enforce a minimum delay before the next announce to avoid killing CPU by iterating network interfaces.
RateLimiterTask = Task.Delay(1000);
ProcessingAnnounces = false;
break;
}
infoHash = PendingAnnounces.Dequeue();
}
string message = string.Format(BaseSearchString, ListenPort, infoHash.ToHex());
byte[] data = Encoding.ASCII.GetBytes(message);
foreach (var nic in nics)
{
try {
sendingClient.Client.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.MulticastInterface, IPAddress.HostToNetworkOrder(nic.GetIPProperties().GetIPv4Properties().Index));
await sendingClient.SendAsync(data, data.Length, MulticastAddressV4).ConfigureAwait(false);
} catch {
// If data can't be sent, just ignore the error
}
}
}
}
