From efc68ad803a8ceb3aa5639980e5f6e957d4070c3 Mon Sep 17 00:00:00 2001
From: Christoph Hagen <christoph@spacemasters.eu>
Date: Mon, 2 May 2022 17:27:56 +0200
Subject: [PATCH] Allow compensation of DST

---
 Sesame/ContentView.swift | 13 ++++++++++---
 Sesame/KeyView.swift     | 12 +++++++++++-
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/Sesame/ContentView.swift b/Sesame/ContentView.swift
index 491a5c1..735754d 100644
--- a/Sesame/ContentView.swift
+++ b/Sesame/ContentView.swift
@@ -8,6 +8,9 @@ struct ContentView: View {
     @AppStorage("counter")
     var nextMessageCounter: Int = 0
 
+    @AppStorage("compensate")
+    var isCompensatingDaylightTime: Bool = false
+
     @State
     var keyManager = KeyManagement()
 
@@ -31,6 +34,10 @@ struct ContentView: View {
     @State
     private var showHistorySheet = false
 
+    var compensationTime: UInt32 {
+        isCompensatingDaylightTime ? 3600 : 0
+    }
+
     var isPerformingRequests: Bool {
         hasActiveRequest ||
         state == .waitingForResponse
@@ -109,7 +116,7 @@ struct ContentView: View {
             .frame(width: geo.size.width, height: geo.size.height)
             .animation(.easeInOut, value: state.color)
             .sheet(isPresented: $showKeySheet) {
-                KeyView(keyManager: $keyManager)
+                KeyView(keyManager: $keyManager, isCompensatingDaylightTime: $isCompensatingDaylightTime)
             }
             .sheet(isPresented: $showHistorySheet) {
                 HistoryView(manager: history)
@@ -126,8 +133,9 @@ struct ContentView: View {
 
         let count = UInt32(nextMessageCounter)
         let sentTime = Date()
+        // Add time to compensate that the device is using daylight savings time
         let content = Message.Content(
-            time: sentTime.timestamp,
+            time: sentTime.timestamp + compensationTime,
             id: count)
         let message = content.authenticate(using: key)
         let historyItem = HistoryItem(sent: message, date: sentTime)
@@ -139,7 +147,6 @@ struct ContentView: View {
             responseTime = receivedTime
             state = newState
             let finishedItem = historyItem.didReceive(response: newState, date: receivedTime, message: message)
-            print("Interval: \(receivedTime.timeIntervalSince(sentTime))", "\(finishedItem.roundTripTime ?? -1)")
             process(item: finishedItem)
         }
     }
diff --git a/Sesame/KeyView.swift b/Sesame/KeyView.swift
index 170e2cf..1e001ba 100644
--- a/Sesame/KeyView.swift
+++ b/Sesame/KeyView.swift
@@ -5,6 +5,9 @@ struct KeyView: View {
     @Binding
     var keyManager: KeyManagement
 
+    @Binding
+    var isCompensatingDaylightTime: Bool
+
     var body: some View {
         GeometryReader { geo in
             VStack(alignment: .leading, spacing: 16) {
@@ -13,6 +16,11 @@ struct KeyView: View {
                         keyManager: $keyManager,
                         type: keyType)
                 }
+                Toggle(isOn: $isCompensatingDaylightTime) {
+                    Text("Compensate daylight savings time")
+                }
+                Text("If the remote has daylight savings time wrongly set, then the time validation will fail. Use this option to send messages with adjusted timestamps. Warning: Incorrect use of this option will allow replay attacks.")
+                    .font(.caption)
             }.padding()
         }
     }
@@ -20,6 +28,8 @@ struct KeyView: View {
 
 struct KeyView_Previews: PreviewProvider {
     static var previews: some View {
-        KeyView(keyManager: .constant(KeyManagement()))
+        KeyView(
+            keyManager: .constant(KeyManagement()),
+            isCompensatingDaylightTime: .constant(true))
     }
 }