Hey all here is an example you can try out: https://github.com/paxsonsa/quic-swift-demo
I am prototype a QUIC base application system with a client and server. My server is a simple test to experiment with QUIC and Network Framework but I am see some odd behaviour.
Selecting Stream Direction for new streams
In the example below, we are creating a new multiplexed QUIC connection and establish a new stream once the group connection is ready. In some cases, I want to be able to use a different stream kind (uni/bi).
By specifying the options, I get an error in Xcode console like so:
running....
group state: waiting(POSIXErrorCode(rawValue: 50): Network is down)
group state: ready
Connected using QUIC!
nw_endpoint_flow_setup_cloned_protocols [C3 127.0.0.1:4567 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: lo0)] could not find protocol to join in existing protocol stack
nw_endpoint_flow_failed_with_error [C3 127.0.0.1:4567 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: lo0)] failed to clone from flow, moving directly to failed state
Main Connection State: failed(POSIXErrorCode(rawValue: 50): Network is down)
quic_recovery_pto PTO fired after validation
Here is my swift code:
//
// main.swift
// QuicTool
//
// Created by Andrew Paxson on 2024-01-14.
//
import Foundation
import Network
/// Helper function to create a message frame.
func createMessage(version: UInt8, messageType: UInt8, message: String) -> Data {
let messageData = message.data(using: .utf8) ?? Data()
let length = UInt32(messageData.count)
var data = Data()
data.append(version)
data.append(messageType)
// Convert length to 4 bytes and append (big-endian format)
let bigEndianLength = length.bigEndian
data.append(contentsOf: withUnsafeBytes(of: bigEndianLength) { Array($0) })
// Append 2 bytes of padding for 8-byte alignment
data.append(Data(repeating: 0, count: 2))
// Add Message Data.
data.append(messageData)
return data
}
// Queue for QUIC things.
let queue = DispatchQueue(label: "quic", qos: .userInteractive)
// Create Inital Options for the tunnel.
// This is using an insecure connection as this operation is meant to be local network.
let endpoint = NWEndpoint.hostPort(host: "127.0.0.1", port: .init(integerLiteral: 4567))
let options = NWProtocolQUIC.Options(alpn: ["demo"])
// Set the initial stream to bidirectional.
options.direction = .bidirectional
sec_protocol_options_set_verify_block(options.securityProtocolOptions, { (sec_protocol_metadata, sec_trust, sec_protocol_verify_complete) in
sec_protocol_verify_complete(true)
}, queue)
let parameters = NWParameters(quic: options)
// 1) Create a new multiplexed connection
let descriptor = NWMultiplexGroup(to: endpoint)
let group = NWConnectionGroup(with: descriptor, using: parameters)
var mainConn: NWConnection? = nil
// Here we are establishing a state handler for when the connection to the
// the server is neogiated and "ready". Once its ready we want to establish a
// stream using the group with the options set.
//
// This is the main location of the issue we are seeing where the stream is
// established and the data is sent but never updated.
group.stateUpdateHandler = { newState in
print("group state: \(newState)")
switch newState {
// Once the tunnel is established, create a new stream with bidirectional parameters.
case .ready:
print("Connected using QUIC!")
// 2) In normal application I may want to open different kinds of streams in providing
// new options. Is there a better way to select the stream kind for subsequent streams?
let options = NWProtocolQUIC.Options(alpn: ["demo"])
options.direction = .bidirectional
// When providing unique options the stream will fail. Removeing the using argument works.
mainConn = group.extract()! // force unwrap
mainConn?.stateUpdateHandler = { state in
print("Main Connection State: \(state)")
switch state {
case .ready:
// Once the connection is ready, lets send some sweet data sauce.
//
// By establishing this new stream and sending data, on the server this causes the inital
// stream with no handle to be open.
let version: UInt8 = 1
let messageType: UInt8 = 1
let message = "hello, I am from the multiplex group ready."
let messageData = createMessage(version: version, messageType: messageType, message: message)
mainConn?.send(content: messageData, isComplete: true, completion: .contentProcessed({ sendError in
if let error = sendError {
print("There was an error sending data: \(error)")
} else {
print("Data was sent successfully from Main Connection.")
}
}))
default:
break
}
}
// Don't forget to start the connection.
mainConn?.start(queue: queue)
default:
break
}
}
// Receive new incoming streams initiated by the remote endpoint
// this is not used for this example.
group.newConnectionHandler = { conn in
print("New Connection: \(conn)")
// Set state update handler on incoming stream
conn.stateUpdateHandler = { newState in
print("newState: \(newState) for \(conn)")
switch newState {
case .ready:
print("got a new stream!")
default:
break
}
}
// Start the incoming stream
conn.start(queue: queue)
}
// Start the group with callback queue
group.start(queue: queue)
print("running....")
// We iterate trying to send data on the new stream we created after the
// connection is established.
while true {
switch mainConn?.state {
case .ready:
// Once the connection is ready, lets send some sweet data sauce.
let version: UInt8 = 1
let messageType: UInt8 = 1
let message = "hello, im from the main loop"
let messageData = createMessage(version: version, messageType: messageType, message: message)
print("Local Stream Send: \(messageData)")
mainConn?.send(content: messageData, completion: .contentProcessed({ sendError in
if let error = sendError {
print("There was an error sending data: \(error)")
}
}))
sleep(1)
default:
continue
}
}
