Trouble sending packets on mac OS 14.6.1

[halfninja]

Hi,

I'm finding this library very useful, but am having some trouble getting it to work properly on Mac.

The library receives queries from elsewhere no problem, but when it comes to sending messages (whether that's a query or a response to one) it never seems to get anywhere. So testing with an basic Node.js script using the multicast-dns module, I can send a hostname query, this library receives it and tries to respond, but it doesn't appear anywhere. I've looked on Wireshark and I can see multicast-dns queries show up on en1 (Wi-Fi), but not for Makeratu.Dns. I confirmed that MulticastService.GetNetworkInterfaces() does include en1.

Any ideas?

[halfninja]

I've just tried the Spike project which is saying the address is already in use - but I don't have any other dotnet or node processes running and I've tried restarting.

Multicast DNS spike
IP address 192.168.68.137
IP address fe80::742f:ef17:475:6c8c%12
IP address fe80::c5b1:79aa:8bff:1e73%13
IP address fe80::ada1:5c39:1f10:725c%14
IP address fe80::ce81:b1c:bd2c:69e%15
21:31:31.596 [DEBUG] Makaretu.Dns.MulticastService - Finding network interfaces
21:31:31.618 [DEBUG] Makaretu.Dns.MulticastService - Found nic 'en1'.
21:31:31.618 [DEBUG] Makaretu.Dns.MulticastService - Found nic 'awdl0'.
21:31:31.618 [DEBUG] Makaretu.Dns.MulticastService - Found nic 'utun0'.
21:31:31.618 [DEBUG] Makaretu.Dns.MulticastService - Found nic 'utun1'.
21:31:31.618 [DEBUG] Makaretu.Dns.MulticastService - Found nic 'utun2'.
21:31:31.618 [DEBUG] Makaretu.Dns.MulticastService - Found nic 'utun3'.
21:31:31.629 [ERROR] Makaretu.Dns.MulticastClient - Cannot setup send socket for 192.168.68.137: Address already in use
=======================================================(inner most exception)===
 (1) System.Net.Sockets.SocketException
================================================================================

Message:
"Address already in use"

Properties:
  SocketError.SocketErrorCode = "AddressAlreadyInUse"
  Int32.ErrorCode = "48"
  Int32.NativeErrorCode = "48"

Stack Trace:
   at System.Net.Sockets.Socket.DoBind(EndPoint endPointSnapshot, SocketAddress socketAddress)
   at System.Net.Sockets.Socket.Bind(EndPoint localEP)
   at Makaretu.Dns.MulticastClient..ctor(Boolean useIPv4, Boolean useIpv6, IEnumerable`1 nics) in /Users/nick/Documents/workspace/net-mdns/src/MulticastClient.cs:line 84

[halfninja]

It turned out that Resilio Sync was the app hogging the address for multicast. I quit Sync and the error has gone away from Spike and more importantly my app's mDNS records are resolving as expected.

Thanks for providing the Spike app, it's a good diagnostic tool!