From 6f1e023012b6e02ff0f718da2b22a28174ce5e76 Mon Sep 17 00:00:00 2001
From: pizzaboxer <pizzaboxer@pizzaboxer.xyz>
Date: Sat, 18 May 2024 23:23:12 +0100
Subject: [PATCH] font mod: validate chosen file is actually a font

---
 Bloxstrap/Resources/Strings.Designer.cs       |  9 +++++++++
 Bloxstrap/Resources/Strings.resx              |  3 +++
 Bloxstrap/UI/ViewModels/Menu/ModsViewModel.cs | 15 +++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/Bloxstrap/Resources/Strings.Designer.cs b/Bloxstrap/Resources/Strings.Designer.cs
index c5faa51..9e16812 100644
--- a/Bloxstrap/Resources/Strings.Designer.cs
+++ b/Bloxstrap/Resources/Strings.Designer.cs
@@ -2565,6 +2565,15 @@ namespace Bloxstrap.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to The file you have chosen does not appear to be a valid font file..
+        /// </summary>
+        public static string Menu_Mods_Misc_CustomFont_Invalid {
+            get {
+                return ResourceManager.GetString("Menu.Mods.Misc.CustomFont.Invalid", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Remove applied font.
         /// </summary>
diff --git a/Bloxstrap/Resources/Strings.resx b/Bloxstrap/Resources/Strings.resx
index f1f8ae4..2122862 100644
--- a/Bloxstrap/Resources/Strings.resx
+++ b/Bloxstrap/Resources/Strings.resx
@@ -967,6 +967,9 @@ Selecting 'No' will ignore this warning and continue installation.</value>
   <data name="Menu.Mods.Misc.CustomFont.Description" xml:space="preserve">
     <value>Forces every in-game font to be a font that you choose.</value>
   </data>
+  <data name="Menu.Mods.Misc.CustomFont.Invalid" xml:space="preserve">
+    <value>The file you have chosen does not appear to be a valid font file.</value>
+  </data>
   <data name="Menu.Mods.Misc.CustomFont.Remove" xml:space="preserve">
     <value>Remove applied font</value>
   </data>
diff --git a/Bloxstrap/UI/ViewModels/Menu/ModsViewModel.cs b/Bloxstrap/UI/ViewModels/Menu/ModsViewModel.cs
index 15ed80a..f5cbb98 100644
--- a/Bloxstrap/UI/ViewModels/Menu/ModsViewModel.cs
+++ b/Bloxstrap/UI/ViewModels/Menu/ModsViewModel.cs
@@ -13,6 +13,13 @@ namespace Bloxstrap.UI.ViewModels.Menu
 
         private bool _usingCustomFont => App.IsFirstRun && App.CustomFontLocation is not null || !App.IsFirstRun && File.Exists(Paths.CustomFont);
 
+        private readonly Dictionary<string, byte[]> FontHeaders = new()
+        {
+            { "ttf", new byte[4] { 0x00, 0x01, 0x00, 0x00 } },
+            { "otf", new byte[4] { 0x4F, 0x54, 0x54, 0x4F } },
+            { "ttc", new byte[4] { 0x74, 0x74, 0x63, 0x66 } } 
+        };
+
         private void ManageCustomFont()
         {
             if (_usingCustomFont)
@@ -32,6 +39,14 @@ namespace Bloxstrap.UI.ViewModels.Menu
                 if (dialog.ShowDialog() != true)
                     return;
 
+                string type = dialog.FileName.Substring(dialog.FileName.Length-3, 3).ToLower();
+
+                if (!File.ReadAllBytes(dialog.FileName).Take(4).SequenceEqual(FontHeaders[type]))
+                {
+                    Frontend.ShowMessageBox(Resources.Strings.Menu_Mods_Misc_CustomFont_Invalid, MessageBoxImage.Error);
+                    return;
+                }
+
                 if (App.IsFirstRun)
                 {
                     App.CustomFontLocation = dialog.FileName;