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Verify Network backend local loopback #31

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83edcbb
feat: verify Network backend loopback
rchatham Aug 6, 2026
d5e6101
Merge remote-tracking branch 'origin/feature/network-migration-backen…
rchatham Aug 9, 2026
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4 changes: 4 additions & 0 deletions PeerConnectivity.xcodeproj/project.pbxproj
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Expand Up @@ -49,6 +49,7 @@
30ASYNCTEST26072102 /* AsyncObservableTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 30ASYNCTEST26072101 /* AsyncObservableTests.swift */; };
30NETADAPTTEST2607302 /* NetworkPeerTransportAdapterTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 30NETADAPTTEST2607301 /* NetworkPeerTransportAdapterTests.swift */; };
30BACKENDTEST2607302 /* PeerConnectionBackendTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 30BACKENDTEST2607301 /* PeerConnectionBackendTests.swift */; };
30LOOPBACKTEST2608062 /* NetworkPeerLoopbackTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 30LOOPBACKTEST2608061 /* NetworkPeerLoopbackTests.swift */; };
30SECURITY26060300000001 /* PeerSecurityConfiguration.swift in Sources */ = {isa = PBXBuildFile; fileRef = 30SECURITY26060300000002 /* PeerSecurityConfiguration.swift */; };
30SECURITY26060300000003 /* PeerSecurityConfigurationTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 30SECURITY26060300000004 /* PeerSecurityConfigurationTests.swift */; };
B20000022F30600000000001 /* ObservableTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = B20000022F30600000000002 /* ObservableTests.swift */; };
Expand Down Expand Up @@ -90,6 +91,7 @@
30ASYNCTEST26072101 /* AsyncObservableTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AsyncObservableTests.swift; sourceTree = "<group>"; };
30NETADAPTTEST2607301 /* NetworkPeerTransportAdapterTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NetworkPeerTransportAdapterTests.swift; sourceTree = "<group>"; };
30BACKENDTEST2607301 /* PeerConnectionBackendTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PeerConnectionBackendTests.swift; sourceTree = "<group>"; };
30LOOPBACKTEST2608061 /* NetworkPeerLoopbackTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NetworkPeerLoopbackTests.swift; sourceTree = "<group>"; };
B20000022F30600000000002 /* ObservableTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ObservableTests.swift; sourceTree = "<group>"; };
B20000022F30600000000004 /* PeerTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PeerTests.swift; sourceTree = "<group>"; };
3080C7DB1D80A1D600AF9EA3 /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = Info.plist; path = Sources/Info.plist; sourceTree = "<group>"; };
Expand Down Expand Up @@ -206,6 +208,7 @@
30ASYNCTEST26072101 /* AsyncObservableTests.swift */,
30NETADAPTTEST2607301 /* NetworkPeerTransportAdapterTests.swift */,
30BACKENDTEST2607301 /* PeerConnectionBackendTests.swift */,
30LOOPBACKTEST2608061 /* NetworkPeerLoopbackTests.swift */,
30PEERMSG2602020000000001 /* PeerMessageTests.swift */,
30SECURITY26060300000004 /* PeerSecurityConfigurationTests.swift */,
B20000022F30600000000002 /* ObservableTests.swift */,
Expand Down Expand Up @@ -375,6 +378,7 @@
30ASYNCTEST26072102 /* AsyncObservableTests.swift in Sources */,
30NETADAPTTEST2607302 /* NetworkPeerTransportAdapterTests.swift in Sources */,
30BACKENDTEST2607302 /* PeerConnectionBackendTests.swift in Sources */,
30LOOPBACKTEST2608062 /* NetworkPeerLoopbackTests.swift in Sources */,
30PEERMSG2602020000000002 /* PeerMessageTests.swift in Sources */,
30SECURITY26060300000003 /* PeerSecurityConfigurationTests.swift in Sources */,
B20000022F30600000000001 /* ObservableTests.swift in Sources */,
Expand Down
17 changes: 16 additions & 1 deletion PeerConnectivityDemo/ViewController.swift
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Expand Up @@ -33,7 +33,10 @@ class ViewController: UIViewController {
}

fileprivate lazy var pcm : PeerConnectionManager = {
let pcm = PeerConnectionManager(serviceType: "local")
let arguments = ProcessInfo.processInfo.arguments
let displayName = ViewController.argumentValue(for: "PCDisplayName") ?? ProcessInfo.processInfo.hostName
let backend : PeerConnectionBackend = arguments.contains("PCNetworkBackend") ? .networkFramework : .multipeerConnectivity
let pcm = PeerConnectionManager(serviceType: "local", displayName: displayName, backend: backend)
Comment thread
rchatham marked this conversation as resolved.
pcm.listenOn({ [weak self] event in
self?.handlePeerConnectionEvent(event)
}, withKey: "demo.events")
Expand Down Expand Up @@ -94,6 +97,9 @@ class ViewController: UIViewController {
configureActions()
refreshUI()
appendLog(kind: "app.ready", detail: "Local peer: \(pcm.peer.displayName)")
if ProcessInfo.processInfo.arguments.contains("PCAutoStart") {
startNetworking()
}
}

override func viewDidDisappear(_ animated: Bool) {
Expand All @@ -112,6 +118,12 @@ extension ViewController : UITextFieldDelegate {
}

private extension ViewController {
static func argumentValue(for key: String) -> String? {
let arguments = ProcessInfo.processInfo.arguments
guard let index = arguments.firstIndex(of: key), arguments.indices.contains(index + 1) else { return nil }
return arguments[index + 1]
}

func configureLayout() {
scrollView.translatesAutoresizingMaskIntoConstraints = false
contentStack.translatesAutoresizingMaskIntoConstraints = false
Expand Down Expand Up @@ -507,14 +519,17 @@ private extension ViewController {
case .ready:
appendLog(kind: "session.ready", detail: "Manager ready")
case .started:
print("PeerConnectivityDemo started networking")
appendLog(kind: "session.started", detail: mode.rawValue)
case .ended:
appendLog(kind: "session.ended", detail: "Manager stopped")
case .devicesChanged(let peer, let peers):
print("PeerConnectivityDemo devices changed: \(peer.displayName) \(peer.status) connected: \(peers.map { $0.displayName })")
connectedPeers = peers
if !peers.isEmpty { checkedItems.insert(.peerConnected) }
appendLog(kind: "peers.connected.changed", detail: "Changed: \(peer.displayName) [\(statusText(peer.status))]", peers: peers)
case .foundPeer(let peer):
print("PeerConnectivityDemo found peer: \(peer.displayName)")
checkedItems.insert(.peerDiscovered)
appendLog(kind: "peer.found", detail: peer.displayName, peers: [peer])
case .foundPeerWithDiscoveryInfo(let peer, let discoveryInfo):
Expand Down
77 changes: 77 additions & 0 deletions PeerConnectivityTests/NetworkPeerLoopbackTests.swift
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@@ -0,0 +1,77 @@
//
// NetworkPeerLoopbackTests.swift
// PeerConnectivityTests
//
// Created by Reid Chatham on 8/6/26.
// Copyright © 2026 Reid Chatham. All rights reserved.
//

import XCTest
@testable import PeerConnectivity

private struct LoopbackMessage : PeerMessage, Equatable {
internal static let messageType = "loopback-message"
internal let text : String
}

final class NetworkPeerLoopbackTests : XCTestCase {

internal func testNetworkBackendDiscoversConnectsAndExchangesMessage() {
guard #available(iOS 13.0, macOS 10.15, *) else { return }

let serviceType = "pctest-\(UUID().uuidString.prefix(8).lowercased())"
let alice = PeerConnectionManager(serviceType: serviceType,
connectionType: .automatic,
displayName: "Alice",
backend: .networkFramework,
transportFactory: .networkFramework)
let bob = PeerConnectionManager(serviceType: serviceType,
connectionType: .automatic,
displayName: "Bob",
backend: .networkFramework,
transportFactory: .networkFramework)
let aliceFoundBob = expectation(description: "Alice found Bob")
let bobFoundAlice = expectation(description: "Bob found Alice")
let aliceConnected = expectation(description: "Alice connected")
let bobConnected = expectation(description: "Bob connected")
let bobReceivedMessage = expectation(description: "Bob received Alice message")

Comment thread
rchatham marked this conversation as resolved.
alice.listenOn({ event in
switch event {
case .foundPeer(let peer) where peer.displayName == "Bob":
aliceFoundBob.fulfill()
case .devicesChanged(peer: let peer, connectedPeers: let connectedPeers)
where peer.displayName == "Bob" && connectedPeers.contains(where: { $0.displayName == "Bob" }):
aliceConnected.fulfill()
default: break
}
}, performListenerInBackground: true, withKey: "alice-events")

bob.listenOn({ event in
switch event {
case .foundPeer(let peer) where peer.displayName == "Alice":
bobFoundAlice.fulfill()
case .devicesChanged(peer: let peer, connectedPeers: let connectedPeers)
where peer.displayName == "Alice" && connectedPeers.contains(where: { $0.displayName == "Alice" }):
bobConnected.fulfill()
default: break
}
}, performListenerInBackground: true, withKey: "bob-events")

bob.observeMessages(ofType: LoopbackMessage.self, forKey: "bob-message") { message, peer in
XCTAssertEqual(peer.displayName, "Alice")
XCTAssertEqual(message, LoopbackMessage(text: "hello"))
bobReceivedMessage.fulfill()
}

bob.start()
alice.start()

wait(for: [aliceFoundBob, bobFoundAlice, aliceConnected, bobConnected], timeout: 15)
alice.sendMessage(LoopbackMessage(text: "hello"), toPeers: alice.connectedPeers)
wait(for: [bobReceivedMessage], timeout: 5)

alice.stop()
bob.stop()
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}
}
6 changes: 6 additions & 0 deletions README.md
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Expand Up @@ -42,6 +42,12 @@ CocoaPods and Carthage are no longer the recommended distribution paths for new

The staged migration toward Apple's Network framework is tracked in [NetworkFrameworkMigrationPlan.md](NetworkFrameworkMigrationPlan.md), with follow-up PR sequencing in [NetworkMigrationPRPlan.md](NetworkMigrationPRPlan.md).

## Experimental Network framework backend

`PeerConnectionManager` can be explicitly initialized with `backend: .networkFramework` on supported OS versions. This backend is still a migration/testing path: it is currently unencrypted and unauthenticated, lacks stream/resource/UI parity, and must not be used for sensitive data until a future hardening pass adds a production trust model.

The default backend remains `.multipeerConnectivity`.


## Creating/Stopping/Starting

Expand Down
52 changes: 30 additions & 22 deletions Sources/NetworkPeerCoordinator.swift
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Expand Up @@ -52,14 +52,16 @@ internal final class NetworkPeerCoordinator<Connection: NetworkPeerFrameSending>
}

internal func receiveFrame(_ frame: PeerNetworkFrame, from connection: Connection) {
queue.sync {
let event : PeerSessionEvent? = queue.sync {
switch frame.kind {
case .handshake:
receiveHandshake(frame.payload, from: connection)
return receiveHandshake(frame.payload, from: connection)
case .data:
receiveData(frame.payload, from: connection)
return receiveData(frame.payload, from: connection)
}
}
guard let event = event else { return }
sessionObserver.value = event
}

internal func sendData(_ data: Data, toPeers peers: [Peer] = []) {
Expand All @@ -69,14 +71,16 @@ internal final class NetworkPeerCoordinator<Connection: NetworkPeerFrameSending>
}

internal func removeConnection(_ connection: Connection) {
queue.sync {
let event : PeerSessionEvent? = queue.sync {
let identifier = ObjectIdentifier(connection)
pendingConnections.removeValue(forKey: identifier)
guard let identity = connectionIdentities.removeValue(forKey: identifier) else { return }
guard registry.connection(for: identity) === connection else { return }
guard let identity = connectionIdentities.removeValue(forKey: identifier) else { return nil }
guard registry.connection(for: identity) === connection else { return nil }
registry.remove(identity: identity)
sessionObserver.value = .devicesChanged(peer: Peer(identity: identity, status: .notConnected))
return .devicesChanged(peer: Peer(identity: identity, status: .notConnected))
}
guard let event = event else { return }
sessionObserver.value = event
}

internal func cancelAllConnections() {
Expand All @@ -89,45 +93,49 @@ internal final class NetworkPeerCoordinator<Connection: NetworkPeerFrameSending>
}

internal func foundPeer(identity: PeerIdentity) {
queue.sync {
guard identity != localPeer.identity else { return }
let event : PeerBrowserEvent? = queue.sync {
guard identity != localPeer.identity else { return nil }
let peer = Peer(identity: identity, status: .notConnected)
discoveredPeers[identity] = peer
browserObserver.value = .foundPeer(peer, discoveryInfo: nil)
return .foundPeer(peer, discoveryInfo: nil)
}
guard let event = event else { return }
browserObserver.value = event
}

internal func lostPeer(identity: PeerIdentity) {
queue.sync {
guard identity != localPeer.identity else { return }
let event : PeerBrowserEvent? = queue.sync {
guard identity != localPeer.identity else { return nil }
let peer = discoveredPeers.removeValue(forKey: identity) ?? Peer(identity: identity, status: .notConnected)
browserObserver.value = .lostPeer(peer)
return .lostPeer(peer)
}
guard let event = event else { return }
browserObserver.value = event
}

fileprivate func receiveHandshake(_ data: Data, from connection: Connection) {
fileprivate func receiveHandshake(_ data: Data, from connection: Connection) -> PeerSessionEvent? {
guard let handshake = try? JSONDecoder().decode(PeerNetworkHandshake.self, from: data),
handshake.protocolVersion == PeerNetworkHandshake.currentProtocolVersion else {
rejectHandshake(from: connection)
return
return nil
}

guard handshake.identity != localPeer.identity else {
rejectHandshake(from: connection)
return
return nil
}

let identifier = ObjectIdentifier(connection)
let pending = pendingConnections.removeValue(forKey: identifier)
let direction = pending?.direction ?? NetworkPeerConnectionDirection.inbound
let wasConnected = registry.connection(for: handshake.identity) != nil
let isRegistered = registry.register(connection, for: handshake.identity, direction: direction)
guard isRegistered else { return }
guard isRegistered else { return nil }

removeConnectionIdentity(for: handshake.identity)
connectionIdentities[identifier] = handshake.identity
guard !wasConnected else { return }
sessionObserver.value = .devicesChanged(peer: Peer(identity: handshake.identity, status: .connected))
guard !wasConnected else { return nil }
return .devicesChanged(peer: Peer(identity: handshake.identity, status: .connected))
}

fileprivate func rejectHandshake(from connection: Connection) {
Expand All @@ -139,9 +147,9 @@ internal final class NetworkPeerCoordinator<Connection: NetworkPeerFrameSending>
connectionIdentities = connectionIdentities.filter { $0.value != identity }
}

fileprivate func receiveData(_ data: Data, from connection: Connection) {
guard let identity = connectionIdentities[ObjectIdentifier(connection)] else { return }
sessionObserver.value = .didReceiveData(peer: Peer(identity: identity, status: .connected), data: data)
fileprivate func receiveData(_ data: Data, from connection: Connection) -> PeerSessionEvent? {
guard let identity = connectionIdentities[ObjectIdentifier(connection)] else { return nil }
return .didReceiveData(peer: Peer(identity: identity, status: .connected), data: data)
}

fileprivate func sendHandshake(on connection: Connection) {
Expand Down
9 changes: 5 additions & 4 deletions Sources/NetworkPeerTransport.swift
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Expand Up @@ -102,9 +102,10 @@ internal final class NetworkPeerConnection : NetworkPeerConnectionCancellable {
}

internal static func parameters() -> NWParameters {
// Network transport remains internal scaffolding; before exposing it publicly,
// provide app-configurable TLS identity or PSK verification for authenticated sessions.
let parameters = NWParameters(tls: NWProtocolTLS.Options(), tcp: NWProtocolTCP.Options())
// Network transport remains experimental opt-in scaffolding; a later hardening
// pass must provide app-configurable TLS identity or PSK verification before
// recommending this backend for production sessions.
let parameters = NWParameters.tcp
parameters.includePeerToPeer = true
return parameters
}
Expand Down Expand Up @@ -179,7 +180,7 @@ internal final class NetworkPeerBrowser : NetworkPeerBrowsing {
resultHandler: ResultHandler? = nil,
stateHandler: StateHandler? = nil) {
let service = PeerNetworkBonjourService(serviceType: serviceType)
let descriptor = NWBrowser.Descriptor.bonjour(type: service.bonjourType, domain: nil)
let descriptor = NWBrowser.Descriptor.bonjourWithTXTRecord(type: service.bonjourType, domain: nil)
browser = NWBrowser(for: descriptor, using: NetworkPeerConnection.parameters())
self.queue = queue
self.resultHandler = resultHandler
Expand Down
6 changes: 6 additions & 0 deletions Sources/Peer.swift
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Expand Up @@ -92,6 +92,12 @@ public struct Peer {
identity = PeerIdentity(peerID: peerID)
status = .currentUser
}

internal init(networkDisplayName displayName: String) {
peerID = MCPeerID(displayName: displayName)
identity = PeerIdentity(identifier: UUID().uuidString, displayName: displayName)
status = .currentUser
}
}

extension PeerIdentity {
Expand Down
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