From 822202e37d2210a8d551b229a28f03e779ed5eec Mon Sep 17 00:00:00 2001
From: Benjamin Erhart <berhart@netzarchitekten.com>
Date: Tue, 14 Apr 2026 18:57:37 +0200
Subject: [PATCH] Issue #3: First implementation of a DoH configuration
 setting.

---
 dns/HomeView.swift  | 11 +++----
 dns/ViewModel.swift | 79 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+), 6 deletions(-)

diff --git a/dns/HomeView.swift b/dns/HomeView.swift
index d95d302..765a48c 100644
--- a/dns/HomeView.swift
+++ b/dns/HomeView.swift
@@ -39,7 +39,6 @@ struct HomeView: View {
     @EnvironmentObject
     private var viewModel: ViewModel
 
-    @State private var isEnabled = false
     @State private var serviceStatus: ServiceStatus = .operational
 
     private let falsePositiveURL = URL(string: "https://www.sr2.uk/contact")!
@@ -58,14 +57,14 @@ struct HomeView: View {
                         VStack(alignment: .leading, spacing: 4) {
                             Text("DNS Protection")
                                 .font(.headline)
-                            Text(isEnabled ? "Active" : "Inactive")
+                            Text(viewModel.isDnsEnabled ? "Active" : "Inactive")
                                 .font(.caption)
-                                .foregroundStyle(isEnabled ? .green : .secondary)
+                                .foregroundStyle(viewModel.isDnsEnabled ? .green : .secondary)
                         }
 
                         Spacer()
 
-                        Toggle("", isOn: $isEnabled)
+                        Toggle("", isOn: $viewModel.isDnsEnabled)
                             .labelsHidden()
                             .tint(.green)
                     }
@@ -95,7 +94,7 @@ struct HomeView: View {
                 }
 
                 // Status section
-                if isEnabled {
+                if viewModel.isDnsEnabled {
                     Section {
                         HStack {
                             Label("Status", systemImage: "checkmark.circle.fill")
@@ -213,7 +212,7 @@ struct HomeView: View {
                 }
             }
             .navigationTitle("SR2® Cloud DNS")
-            .animation(.default, value: isEnabled)
+            .animation(.default, value: viewModel.isDnsEnabled)
         }
     }
 }
diff --git a/dns/ViewModel.swift b/dns/ViewModel.swift
index 4c82680..4ec1ada 100644
--- a/dns/ViewModel.swift
+++ b/dns/ViewModel.swift
@@ -7,10 +7,89 @@
 
 import Foundation
 import Combine
+import NetworkExtension
+import OSLog
 
 class ViewModel: NSObject, ObservableObject {
 
+    // TODO: Store this in UserDefaults
     @Published
     var blocklist: BlocklistOption = .secure
 
+    // TODO: Store this in UserDefaults
+    @Published
+    var isDnsEnabled = false {
+        didSet {
+            if !isProgrammaticChange {
+                toggleDns()
+            }
+            else {
+                // Reset, so next one is recognized as coming from the user again.
+                isProgrammaticChange = false
+            }
+        }
+    }
+
+    private var isProgrammaticChange = false
+
+
+    private let manager = NEDNSSettingsManager.shared()
+
+    private let log = Logger(subsystem: String(describing: ViewModel.self), category: String(describing: ViewModel.self))
+
+
+    func toggleDns() {
+        Task {
+            if isDnsEnabled {
+                do {
+                    try await manager.loadFromPreferences()
+                }
+                catch {
+                    log.error("Error loading preferences: \(error)")
+
+                    delayedToggle(false)
+
+                    return
+                }
+
+                let settings = NEDNSOverHTTPSSettings(servers: [blocklist.ipv4, blocklist.ipv6])
+                settings.serverURL = URL(string: "https://\(blocklist.server)")
+                settings.matchDomains = [""]
+
+
+                manager.dnsSettings = settings
+                manager.localizedDescription = blocklist.description
+
+                do {
+                    try await manager.saveToPreferences()
+                }
+                catch {
+                    log.error("Error storing preferences: \(error)")
+
+                    delayedToggle(false)
+                }
+            }
+            else {
+                do {
+                    try await manager.removeFromPreferences()
+                }
+                catch {
+                    log.error("Error removing preferences: \(error)")
+
+                    delayedToggle(true)
+                }
+            }
+        }
+    }
+
+    private func delayedToggle(_ enabled: Bool) {
+        Task {
+            try? await Task.sleep(nanoseconds: 500_000_000)
+
+            await MainActor.run {
+                isProgrammaticChange = true
+                isDnsEnabled = enabled
+            }
+        }
+    }
 }