From d3157e4d4805337742d8d70a67a25e0e04182f47 Mon Sep 17 00:00:00 2001
From: Lorenz Stechauner <lorenz.stechauner@necronda.net>
Date: Wed, 6 Aug 2025 12:31:19 +0200
Subject: [PATCH] ElwigData: Check zip file integrity

---
 Elwig/App.xaml.cs                 |  4 ++--
 Elwig/Elwig.csproj                |  1 +
 Elwig/Helpers/Export/ElwigData.cs |  4 +++-
 Elwig/Helpers/Extensions.cs       | 13 +++++++++++++
 Elwig/Windows/MainWindow.xaml.cs  |  4 ++--
 5 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/Elwig/App.xaml.cs b/Elwig/App.xaml.cs
index df7f047..c08cec3 100644
--- a/Elwig/App.xaml.cs
+++ b/Elwig/App.xaml.cs
@@ -240,9 +240,9 @@ namespace Elwig {
             }
         }
 
-        public static void ReplaceDatabase(string filename) {
+        public static async Task ReplaceDatabase(string filename) {
             try {
-                ElwigData.ImportDatabase(filename);
+                await ElwigData.ImportDatabase(filename);
                 MessageBox.Show("Das Ersetzen war erfolgreich!\n\nBitte starten Sie Elwig neu!", "Datenbank ersetzen", MessageBoxButton.OK, MessageBoxImage.Information);
                 ForceShutdown = true;
                 Current.Shutdown();
diff --git a/Elwig/Elwig.csproj b/Elwig/Elwig.csproj
index 3e0aaf0..31f09d0 100644
--- a/Elwig/Elwig.csproj
+++ b/Elwig/Elwig.csproj
@@ -35,6 +35,7 @@
     <PackageReference Include="RazorLight" Version="2.3.1" />
     <PackageReference Include="ScottPlot.WPF" Version="5.0.55" />
     <PackageReference Include="SQLitePCLRaw.bundle_e_sqlite3" Version="3.0.0" />
+    <PackageReference Include="System.IO.Hashing" Version="9.0.8" />
     <PackageReference Include="System.IO.Ports" Version="9.0.8" />
     <PackageReference Include="System.Text.Encoding.CodePages" Version="9.0.8" />
   </ItemGroup>
diff --git a/Elwig/Helpers/Export/ElwigData.cs b/Elwig/Helpers/Export/ElwigData.cs
index c196c43..3868be4 100644
--- a/Elwig/Helpers/Export/ElwigData.cs
+++ b/Elwig/Helpers/Export/ElwigData.cs
@@ -75,6 +75,7 @@ namespace Elwig.Helpers.Export {
                 foreach (var filename in filenames) {
                     // TODO read encrypted files
                     using var zip = ZipFile.Open(filename, ZipArchiveMode.Read);
+                    await zip.CheckIntegrity();
 
                     var version = zip.GetEntry("version");
                     using (var reader = new StreamReader(version!.Open(), Utils.UTF8)) {
@@ -370,11 +371,12 @@ namespace Elwig.Helpers.Export {
             }.Export(filename);
         }
 
-        public static void ImportDatabase(string filename) {
+        public static async Task ImportDatabase(string filename) {
             var oldName = Path.ChangeExtension(App.Config.DatabaseFile, ".old.sqlite3");
             var newName = Path.ChangeExtension(App.Config.DatabaseFile, ".new.sqlite3");
             try {
                 using (var zip = ZipFile.Open(filename, ZipArchiveMode.Read)) {
+                    await zip.CheckIntegrity();
                     var db = zip.GetEntry("database.sqlite3")!;
                     db.ExtractToFile(newName, true);
                 }
diff --git a/Elwig/Helpers/Extensions.cs b/Elwig/Helpers/Extensions.cs
index bae2d8c..d616225 100644
--- a/Elwig/Helpers/Extensions.cs
+++ b/Elwig/Helpers/Extensions.cs
@@ -1,5 +1,7 @@
 using System;
 using System.IO;
+using System.IO.Compression;
+using System.IO.Hashing;
 using System.Net.Http;
 using System.Runtime.InteropServices;
 using System.Threading;
@@ -95,5 +97,16 @@ namespace Elwig.Helpers {
             await download.CopyToAsync(destination, 81920, relativeProgress, cancellationToken);
             progress.Report(100.0);
         }
+
+        public static async Task CheckIntegrity(this ZipArchive zip) {
+            var crc = new Crc32();
+            foreach (var entry in zip.Entries) {
+                crc.Reset();
+                using var stream = entry.Open();
+                await crc.AppendAsync(stream);
+                if (crc.GetCurrentHashAsUInt32() != entry.Crc32)
+                    throw new InvalidDataException($"CRC-32 mismatch in '{entry.FullName}'");
+            }
+        }
     }
 }
diff --git a/Elwig/Windows/MainWindow.xaml.cs b/Elwig/Windows/MainWindow.xaml.cs
index e5f8351..a7fef8e 100644
--- a/Elwig/Windows/MainWindow.xaml.cs
+++ b/Elwig/Windows/MainWindow.xaml.cs
@@ -266,8 +266,8 @@ namespace Elwig.Windows {
                     if (res != MessageBoxResult.OK)
                         return;
 
-                    await App.MainDispatcher.BeginInvoke(() => {
-                        App.ReplaceDatabase(filename);
+                    await App.MainDispatcher.BeginInvoke(async () => {
+                        await App.ReplaceDatabase(filename);
                     });
                 } catch (HttpRequestException exc) {
                     MessageBox.Show("Eventuell Internetverbindung prüfen!\n\n" + exc.Message, "Datenbank herunterladen", MessageBoxButton.OK, MessageBoxImage.Error);