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Writing an `NWProtocolFramerImplementation` to run on top of `NWProtocolWebSocket`
Hi All, I am trying to write an NWProtocolFramerImplementation that will run after Websockets. I would like to achieve two goals with this Handle the application-layer authentication handshake in-protocol so my external application code can ignore it Automatically send pings periodically so my application can ignore keepalive I am running into trouble because the NWProtocolWebsocket protocol parses websocket metadata into NWMessage's and I don't see how to handle this at the NWProtocolFramerImplementation level Here's what I have (see comments for questions) class CoolProtocol: NWProtocolFramerImplementation { static let label = "Cool" private var tempStatusCode: Int? required init(framer: NWProtocolFramer.Instance) {} static let definition = NWProtocolFramer.Definition(implementation: CoolProtocol.self) func start(framer: NWProtocolFramer.Instance) -> NWProtocolFramer.StartResult { return .willMarkReady } func wakeup(framer: NWProtocolFramer.Instance) { } func stop(framer: NWProtocolFramer.Instance) -> Bool { return true } func cleanup(framer: NWProtocolFramer.Instance) { } func handleOutput(framer: NWProtocolFramer.Instance, message: NWProtocolFramer.Message, messageLength: Int, isComplete: Bool) { // How to write a "Message" onto the next protocol handler. I don't want to just write plain data. // How to tell the websocket protocol framer that it's a ping/pong/text/binary... } func handleInput(framer: NWProtocolFramer.Instance) -> Int { // How to handle getting the input from websockets in a message format? I don't want to just get "Data" I would like to know if that data is // a ping, pong, text, binary, ... } } If I implementing this protocol at the application layer, here's how I would send websocket messages class Client { ... func send(string: String) async throws { guard let data = string.data(using: .utf8) else { return } let metadata = NWProtocolWebSocket.Metadata(opcode: .text) let context = NWConnection.ContentContext( identifier: "textContext", metadata: [metadata] ) self.connection.send( content: data, contentContext: context, isComplete: true, completion: .contentProcessed({ [weak self] error in ... }) ) } } You see at the application layer I have access to this context object and can access NWProtocolMetadata on the input and output side, but in NWProtocolFramer.Instance I only see final func writeOutput(data: Data) which doesn't seem to include context anywhere. Is this possible? If not how would you recommend I handle this? I know I could re-write the entire Websocket protocol framer, but it feels like I shouldn't have to if framers are supposed to be able to stack.
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1w
NWParemeters.requiredLocalEndpoint is ignored in VisionOS
I have a an application that incorporates a RTCP client to communicate with a local networked device. The device's RTCP implementation requires that the local RTCP port be 6970 even for the initial outbound connection. I have an implementation that is working just fine on macOS and iOS, but I when I port this to visionOS, I see that the local connection is ignoring my .requiredLocalEndpoint specification and choosing a random port (I can see this is happening in Wireshark via the VisionOS simulator.) let remoteRtcpEndpoint = NWEndpoint.hostPort(host: NWEndpoint.Host(remoteRTCPAddress), port: NWEndpoint.Port(rawValue: remoteRTCPPort)!) let rtcpParameters = NWParameters.udp let localEndpoint = NWEndpoint.hostPort(host: NWEndpoint.Host("0.0.0.0"), port: NWEndpoint.Port(rawValue: localRTPPort)!) Self.logger.info("Starting rtcp with local port \(localRTPPort), remote address \(remoteRTCPAddress), endpoint \(String(describing: localEndpoint))") rtcpParameters.requiredLocalEndpoint = localEndpoint rtcpParameters.allowLocalEndpointReuse = true remoteRtcpConnection = NWConnection(to: remoteRtcpEndpoint, using: rtcpParameters) remoteRtcpConnection.start(queue: .global()) And here's the code that sends the command. remoteRtcpConnection.send(content: RtcpPacket.vdly(delayMs: HUGE_FIXED_VDLY_MS).packet(), completion: .contentProcessed({ error in if let error = error { Self.logger.warning("Error sending VDLY packet \(error)") continuation.resume(throwing: error) } else { Self.logger.debug("VDLY Sent \(self.HUGE_FIXED_VDLY_MS)") continuation.resume(returning: ()) } })) If this is a known limitation of the Network framework, should I revert to BSD sockets or something? How can I work around this? Additionally, I don't have a VisionOS device, so I am using the simulator, could this be a problem with the simulator's network bridge?
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Mar ’24