feat: add XPC communication to Network Extension (#29)

Co-authored-by: Ethan Dickson <[email protected]>

Author: coadler

Coder Desktop/Coder Desktop/Coder_Desktop.entitlements

@@ -10,6 +10,10 @@
 	<true/>
 	<key>com.apple.security.app-sandbox</key>
 	<true/>
+	<key>com.apple.security.application-groups</key>
+	<array>
+		<string>$(TeamIdentifierPrefix)com.coder.Coder-Desktop</string>
+	</array>
 	<key>com.apple.security.files.user-selected.read-only</key>
 	<true/>
 	<key>com.apple.security.network.client</key>

Coder Desktop/Coder Desktop/Coder_DesktopApp.swift

@@ -49,8 +49,7 @@ class AppDelegate: NSObject, NSApplicationDelegate {
 
     func applicationShouldTerminate(_: NSApplication) -> NSApplication.TerminateReply {
         Task {
-            await vpn.stop()
-            NSApp.reply(toApplicationShouldTerminate: true)
+            await vpn.quit()
         }
         return .terminateLater
     }

Coder Desktop/Coder Desktop/Info.plist

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>NetworkExtension</key>
+	<dict>
+		<key>NEMachServiceName</key>
+		<string>$(TeamIdentifierPrefix)com.coder.Coder-Desktop.VPN</string>
+	</dict>
+</dict>
+</plist>

Coder Desktop/Coder Desktop/VPNService.swift

@@ -1,6 +1,8 @@
 import NetworkExtension
 import os
 import SwiftUI
+import VPNLib
+import VPNXPC
 
 @MainActor
 protocol VPNService: ObservableObject {
@@ -43,6 +45,9 @@ enum VPNServiceError: Error, Equatable {
 @MainActor
 final class CoderVPNService: NSObject, VPNService {
     var logger = Logger(subsystem: Bundle.main.bundleIdentifier!, category: "vpn")
+    lazy var xpc: VPNXPCInterface = .init(vpn: self)
+    var terminating = false
+
     @Published var tunnelState: VPNServiceState = .disabled
     @Published var sysExtnState: SystemExtensionState = .uninstalled
     @Published var neState: NetworkExtensionState = .unconfigured
@@ -71,46 +76,45 @@ final class CoderVPNService: NSObject, VPNService {
         }
     }
 
-    var startTask: Task<Void, Never>?
     func start() async {
-        if await startTask?.value != nil {
+        switch tunnelState {
+        case .disabled, .failed:
+            break
+        default:
             return
         }
-        startTask = Task {
-            tunnelState = .connecting
-            await enableNetworkExtension()
 
-            // TODO: enable communication with the NetworkExtension to track state and agents. For
-            //       now, just pretend it worked...
-            tunnelState = .connected
-        }
-        defer { startTask = nil }
-        await startTask?.value
+        // this ping is somewhat load bearing since it causes xpc to init
+        xpc.ping()
+        tunnelState = .connecting
+        await enableNetworkExtension()
+        logger.debug("network extension enabled")
     }
 
-    var stopTask: Task<Void, Never>?
     func stop() async {
-        // Wait for a start operation to finish first
-        await startTask?.value
-        guard state == .connected else { return }
-        if await stopTask?.value != nil {
-            return
-        }
-        stopTask = Task {
-            tunnelState = .disconnecting
-            await disableNetworkExtension()
+        guard tunnelState == .connected else { return }
+        tunnelState = .disconnecting
+        await disableNetworkExtension()
+        logger.info("network extension stopped")
+    }
 
-            // TODO: determine when the NetworkExtension is completely disconnected
-            tunnelState = .disabled
+    // Instructs the service to stop the VPN and then quit once the stop event
+    // is read over XPC.
+    // MUST only be called from `NSApplicationDelegate.applicationShouldTerminate`
+    // MUST eventually call `NSApp.reply(toApplicationShouldTerminate: true)`
+    func quit() async {
+        guard tunnelState == .connected else {
+            NSApp.reply(toApplicationShouldTerminate: true)
+            return
         }
-        defer { stopTask = nil }
-        await stopTask?.value
+        terminating = true
+        await stop()
     }
 
     func configureTunnelProviderProtocol(proto: NETunnelProviderProtocol?) {
         Task {
-            if proto != nil {
-                await configureNetworkExtension(proto: proto!)
+            if let proto {
+                await configureNetworkExtension(proto: proto)
                 // this just configures the VPN, it doesn't enable it
                 tunnelState = .disabled
             } else {
@@ -119,10 +123,39 @@ final class CoderVPNService: NSObject, VPNService {
                     neState = .unconfigured
                     tunnelState = .disabled
                 } catch {
-                    logger.error("failed to remoing network extension: \(error)")
+                    logger.error("failed to remove network extension: \(error)")
                     neState = .failed(error.localizedDescription)
                 }
             }
         }
     }
+
+    func onExtensionPeerUpdate(_ data: Data) {
+        // TODO: handle peer update
+        logger.info("network extension peer update")
+        do {
+            let msg = try Vpn_TunnelMessage(serializedBytes: data)
+            debugPrint(msg)
+        } catch {
+            logger.error("failed to decode peer update \(error)")
+        }
+    }
+
+    func onExtensionStart() {
+        logger.info("network extension reported started")
+        tunnelState = .connected
+    }
+
+    func onExtensionStop() {
+        logger.info("network extension reported stopped")
+        tunnelState = .disabled
+        if terminating {
+            NSApp.reply(toApplicationShouldTerminate: true)
+        }
+    }
+
+    func onExtensionError(_ error: NSError) {
+        logger.error("network extension reported error: \(error)")
+        tunnelState = .failed(.internalError(error.localizedDescription))
+    }
 }

Coder Desktop/Coder Desktop/XPCInterface.swift

@@ -0,0 +1,70 @@
+import Foundation
+import os
+import VPNXPC
+
+@objc final class VPNXPCInterface: NSObject, VPNXPCClientCallbackProtocol, @unchecked Sendable {
+    private var svc: CoderVPNService
+    private let logger = Logger(subsystem: Bundle.main.bundleIdentifier!, category: "VPNXPCInterface")
+    private let xpc: VPNXPCProtocol
+
+    init(vpn: CoderVPNService) {
+        svc = vpn
+
+        let networkExtDict = Bundle.main.object(forInfoDictionaryKey: "NetworkExtension") as? [String: Any]
+        let machServiceName = networkExtDict?["NEMachServiceName"] as? String
+        let xpcConn = NSXPCConnection(machServiceName: machServiceName!)
+        xpcConn.remoteObjectInterface = NSXPCInterface(with: VPNXPCProtocol.self)
+        xpcConn.exportedInterface = NSXPCInterface(with: VPNXPCClientCallbackProtocol.self)
+        guard let proxy = xpcConn.remoteObjectProxy as? VPNXPCProtocol else {
+            fatalError("invalid xpc cast")
+        }
+        xpc = proxy
+
+        super.init()
+
+        xpcConn.exportedObject = self
+        xpcConn.invalidationHandler = { [logger] in
+            Task { @MainActor in
+                logger.error("XPC connection invalidated.")
+            }
+        }
+        xpcConn.interruptionHandler = { [logger] in
+            Task { @MainActor in
+                logger.error("XPC connection interrupted.")
+            }
+        }
+        xpcConn.resume()
+    }
+
+    func ping() {
+        xpc.ping {
+            Task { @MainActor in
+                self.logger.info("Connected to NE over XPC")
+            }
+        }
+    }
+
+    func onPeerUpdate(_ data: Data) {
+        Task { @MainActor in
+            svc.onExtensionPeerUpdate(data)
+        }
+    }
+
+    func onStart() {
+        Task { @MainActor in
+            svc.onExtensionStart()
+        }
+    }
+
+    func onStop() {
+        Task { @MainActor in
+            svc.onExtensionStop()
+        }
+    }
+
+    func onError(_ err: NSError) {
+        Task { @MainActor in
+            svc.onExtensionError(err)
+        }
+    }
+}