From 945a22747312050f6cbe557485dfb61637d77536 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Zieliski?= <bimbej@icloud.com>
Date: Tue, 16 Jul 2024 13:23:49 +0200
Subject: [PATCH] checking base64 format fix

---
 WebAPI/Controllers/DataInboxController.cs | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/WebAPI/Controllers/DataInboxController.cs b/WebAPI/Controllers/DataInboxController.cs
index 64560d0..a036493 100644
--- a/WebAPI/Controllers/DataInboxController.cs
+++ b/WebAPI/Controllers/DataInboxController.cs
@@ -137,7 +137,26 @@ public class DataInboxController : Controller
     // helpers
     private bool IsBase64String(string data)
     {
-        var bytes = new Span<byte>(new byte[256]); 
-        return Convert.TryFromBase64String(data, bytes, out _);
+        if (string.IsNullOrEmpty(data))
+        {
+            return false;
+        }
+        try
+        {
+            var base64Bytes = Convert.FromBase64String(data);
+            
+            var utf8String = Encoding.UTF8.GetString(base64Bytes);
+            
+            var reEncoded = Convert.ToBase64String(Encoding.UTF8.GetBytes(utf8String));
+            return data.TrimEnd('=') == reEncoded.TrimEnd('=');
+        }
+        catch (FormatException)
+        {
+            return false;
+        }
+        catch (DecoderFallbackException)
+        {
+            return false;
+        }
     }
 }
\ No newline at end of file