Hello, I'm working with the Network framework in Swift and have encountered an issue when attempting to create multiple NWListener instances on the same port. I am specifically trying to set the allowLocalEndpointReuse property on the NWParameters used for both listeners, but it seems that even with this property set, the second listener fails to start. Here’s a simplified version of my implementation: import Foundation import Network class UDPServer { private var listener1: NWListener? private var listener2: NWListener? private let port: NWEndpoint.Port init(port: UInt16) { self.port = NWEndpoint.Port(rawValue: port) ?? NWEndpoint.Port(45000) startListeners() } private func startListeners() { let udpOptions = NWProtocolUDP.Options() let params = NWParameters(udp: udpOptions) params.allowLocalEndpointReuse = true // Create first listener do { listener1 = try NWListener(using: params, on: port) listener1?.start(queue: .global()) } catch { print("Failed to create Listener 1: \(error)") } // Create second listener do { listener2 = try NWListener(using: params, on: port) listener2?.start(queue: .global()) } catch { print("Failed to create Listener 2: \(error)") } } } // Usage example let udpServer = UDPServer(port: 45000) RunLoop.main.run() Observations: I expect both listeners to operate without issues since I set allowLocalEndpointReuse to true. However, when I attempt to start the second listener on the same port, it fails with an error. output nw_path_evaluator_evaluate NECP_CLIENT_ACTION_ADD error [48: Address already in use] nw_path_create_evaluator_for_listener nw_path_evaluator_evaluate failed nw_listener_start_on_queue [L2] nw_path_create_evaluator_for_listener failed Listener 1 ready on port 45000 Listener 2 failed: POSIXErrorCode(rawValue: 48): Address already in use Listener 2 cancelled Questions: Is there a limitation in the Network framework regarding multiple listeners on the same port even with allowLocalEndpointReuse? Should I be using separate NWParameters for each listener, or is it acceptable to reuse them? Even when trying to initialize NWParameters with NWProtocolUDP.Options, it doesn't seem to change anything. What steps should I take to modify these properties effectively? If I wanted to set the noDelay option for TCP, how would I do that? Even when initializing NWParameters with init(.tls: , .tcp:), it doesn't seem to have any effect. Any insights or recommendations would be greatly appreciated! Thank you!

Hello Everyone, I’m working on a project that involves multicast communication between processes running on different devices within the same network. For all my Apple devices (macOS, iOS, etc.), I am using NWConnectionGroup, which listens on a multicast address "XX.XX.XX.XX" and a specific multicast port. The issue occurs when a requestor (such as a non-Apple process) sends a multicast request, and the server, which is a process running on an Apple device using NWConnectionGroup (the responder), attempts to reply. The problem is that the response is sent from a different ephemeral port rather than the port on which the multicast request was received. If the client is behind a firewall that blocks unsolicited traffic, the firewall only allows incoming packets on the same multicast port used for the initial request. Since the multicast response is sent from a different ephemeral port, the firewall blocks this response, preventing the requestor from receiving it. Questions: Is there a recommended approach within the NWConnectionGroup or Network.framework to ensure that responses to multicast requests are sent from the same port used for the request? Are there any best practices for handling multicast responses in scenarios where the requestor is behind a restrictive firewall? Any insights or suggestions on how to account for this behavior and ensure reliable multicast communication in such environments would be greatly appreciated. Thanks, Harshal

Hi everyone, I'm currently working on a project where I need to send multicast packets across all available network interfaces using Apple Network Framework's NWConnectionGroup. Specifically, the MacBook (device I am using for sending multicast requests, MacOS: 15.1) is connected to two networks: Wi-Fi (Network 1) and Ethernet (Network 2), and I need to send multicast requests over both interfaces. I tried using the .requiredInterface property as suggested by Eskimo in this post, but I’m running into issues. It seems like I can't create an NWInterface object because it doesn't have any initializers. Here is the code which I wrote: var multicast_group_descriptor : NWMulticastGroup var multicast_endpoint : NWEndpoint multicast_endpoint = NWEndpoint.hostPort(host: NWEndpoint.Host("234.0.0.1"), port: NWEndpoint.Port(rawValue: 49154)!) var connection_group : NWConnectionGroup var multicast_params : NWParameters multicast_params = NWParameters.udp var interface = NWInterface(NWInterface.InterfaceType.wiredEthernet) I get following error: 'NWInterface' cannot be constructed because it has no accessible initializers I also experimented with the .requiredInterfaceType property. Even when I set it to .wiredEthernet and then change it to .wifi, I am still unable to send requests over the Wi-Fi network. Here is the code I wrote: var multicast_params : NWParameters multicast_params = NWParameters.udp multicast_params.allowLocalEndpointReuse = true multicast_params.requiredInterfaceType = .wiredEthernet var ip = multicast_params.defaultProtocolStack.internetProtocol! as! NWProtocolIP.Options ip.disableMulticastLoopback = true connection_group = NWConnectionGroup(with: multicast_group_descriptor, using: multicast_params) connection_group.stateUpdateHandler = { state in print(state) if state == .ready { connection_group.send(content: "Hello from machine on 15".data(using: .utf8)) { error in print("Send to mg1 completed on wired Ethernet with error \(error?.errorCode)") var params = connection_group.parameters params.requiredInterfaceType = .wifi connection_group.send(content: "Hello from machine on 15 P2 on Wi-Fi".data(using: .utf8)) { error in print("Send to mg1 completed on Wi-Fi with error \(error?.errorCode)") } } } } Is this expected behavior when using NWConnectionGroup? Or is there a different approach I should take to ensure multicast requests are sent over both interfaces simultaneously? Any insights or suggestions would be greatly appreciated! Thanks in advance, Harshal

Hello everyone, I'm encountering an issue with Swift and C++ interoperability when passing a void pointer between Swift and C++ functions. When I pass pMessageBuffer (an UnsafeMutableRawPointer) from Swift to MyCppClass.NFCompletion (a static c++ function), which expects a reference to void pointer, Swift throws an error "Cannot convert value of type 'UnsafeMutableRawPointer' to expected argument type 'Optional' ". Here is a sample code to help in better visualization of the usecase. Cpp Code class MyCppClass { public: static void SendData(void *pMessage, TUInt16 pMessageLength) { // Assume vSocket is my Swift object held in C++. vSocket.Send(pMessage, pMessageLength); } static void NFCompletion(void * & pBuffer, TInt64 pErrorCode, VPtr pCompletionFunction) { // Process the buffer. } }; Swift Code: public class MySwiftClass { var vConnection: NWConnection? public init() {} public func Send(_ pMessageBuffer: UnsafeMutableRawPointer, _ pMessageLength: TSUInt16) { let messageData = Data(bytesNoCopy: pMessageBuffer, count: Int(pMessageLength), deallocator: .none) self.vConnection?.send(content: messageData, completion: .contentProcessed { nw_error in var error_code: TSInt64 = 0 if let nw_error = nw_error { error_code = self.InternalGetNetworkErrorCode(nw_error) } // Here's where the issue arises: MyCppClass.NFCompletion(pMessageBuffer, TInt64(error_code), self.uCompletionHandler) }) } // Example function to handle network errors private func InternalGetNetworkErrorCode(_ error: Error) -> TSInt64 { // Implementation to convert nw_error to TSInt64 error code return 0 // Placeholder return value } } Could someone please help me understand why this conversion error occurs? How should I correctly handle passing a void pointer between Swift and C++ functions, ensuring compatibility and proper memory management? Note: TSInt64 is typealias for swift Int and TInt64 is alias of c++ int_64t. Thank you in advance for your assistance! Regards, Harshal