Optimized the project code

Author: XIYUEKONGLING

OpenBioCardServer/Controllers/Classic/ClassicSettingsController.cs

@@ -4,6 +4,7 @@
 using OpenBioCardServer.Models.Entities;
 using OpenBioCardServer.Models.Enums;
 using OpenBioCardServer.Services;
+using OpenBioCardServer.Utilities;
 using OpenBioCardServer.Utilities.Mappers;
 
 namespace OpenBioCardServer.Controllers.Classic;
@@ -174,11 +175,13 @@ public async Task<IActionResult> UpdateSettings([FromBody] ClassicUpdateSettings
         }
     }
 
-    private static string AssetToString(AssetType type, string? text, byte[]? data) => type switch
+    public static string AssetToString(AssetType type, string? text, byte[]? data) => type switch
     {
         AssetType.Text => text ?? string.Empty,
         AssetType.Remote => text ?? string.Empty,
-        AssetType.Image => data != null ? $"data:image/png;base64,{Convert.ToBase64String(data)}" : string.Empty,
+        AssetType.Image => data != null 
+            ? $"data:{ImageHelper.DetectMimeType(data)};base64,{Convert.ToBase64String(data)}" 
+            : string.Empty,
         _ => string.Empty
     };
 }

OpenBioCardServer/Utilities/Base64Validator.cs

@@ -0,0 +1,86 @@
+namespace OpenBioCardServer.Utilities;
+
+public static class Base64Validator
+{
+    /// <summary>
+    /// Calculate the approximate size of decoded Base64 data
+    /// </summary>
+    public static long CalculateBase64Size(string base64String)
+    {
+        if (string.IsNullOrEmpty(base64String))
+            return 0;
+
+        // Remove data URL prefix if present
+        var base64Data = base64String;
+        if (base64String.StartsWith("data:"))
+        {
+            var commaIndex = base64String.IndexOf(',');
+            if (commaIndex >= 0)
+            {
+                base64Data = base64String[(commaIndex + 1)..];
+            }
+        }
+
+        // Remove padding and calculate size
+        var paddingCount = base64Data.EndsWith("==") ? 2 : base64Data.EndsWith("=") ? 1 : 0;
+        var base64Length = base64Data.Length;
+        
+        // Decoded size = (base64Length * 3) / 4 - paddingCount
+        return (base64Length * 3L / 4) - paddingCount;
+    }
+
+    /// <summary>
+    /// Validate if Base64 string size is within limit
+    /// </summary>
+    public static (bool isValid, string? errorMessage) ValidateSize(
+        string base64String, 
+        long maxSizeBytes,
+        string fieldName = "File")
+    {
+        if (string.IsNullOrEmpty(base64String))
+            return (true, null);
+
+        var estimatedSize = CalculateBase64Size(base64String);
+        
+        if (estimatedSize > maxSizeBytes)
+        {
+            var maxSizeMB = maxSizeBytes / 1024.0 / 1024.0;
+            var actualSizeMB = estimatedSize / 1024.0 / 1024.0;
+            
+            return (false, 
+                $"{fieldName} size ({actualSizeMB:F2}MB) exceeds maximum allowed size ({maxSizeMB:F2}MB)");
+        }
+
+        return (true, null);
+    }
+
+    /// <summary>
+    /// Validate image type from Base64 data URL
+    /// </summary>
+    public static (bool isValid, string? errorMessage) ValidateImageType(
+        string base64String,
+        IEnumerable<string> allowedTypes,
+        string fieldName = "File")
+    {
+        if (string.IsNullOrEmpty(base64String))
+            return (true, null);
+
+        if (!base64String.StartsWith("data:"))
+            return (true, null); // Not a data URL, skip type check
+
+        var semicolonIndex = base64String.IndexOf(';');
+        if (semicolonIndex < 0)
+            return (false, $"{fieldName} has invalid data URL format");
+
+        var mimeType = base64String[5..semicolonIndex]; // Skip "data:"
+
+        if (!allowedTypes.Contains(mimeType, StringComparer.OrdinalIgnoreCase))
+        {
+            return (false, 
+                $"{fieldName} type '{mimeType}' is not allowed. " +
+                $"Allowed types: {string.Join(", ", allowedTypes)}");
+        }
+
+        return (true, null);
+    }
+}

OpenBioCardServer/Utilities/ImageHelper.cs

@@ -0,0 +1,30 @@
+namespace OpenBioCardServer.Utilities;
+
+public static class ImageHelper
+{
+    public static string DetectMimeType(byte[] data)
+    {
+        if (data == null || data.Length < 4)
+            return "application/octet-stream";
+
+        // PNG: 89 50 4E 47
+        if (data[0] == 0x89 && data[1] == 0x50 && data[2] == 0x4E && data[3] == 0x47)
+            return "image/png";
+
+        // JPEG: FF D8 FF
+        if (data[0] == 0xFF && data[1] == 0xD8 && data[2] == 0xFF)
+            return "image/jpeg";
+
+        // GIF: 47 49 46 38
+        if (data[0] == 0x47 && data[1] == 0x49 && data[2] == 0x46 && data[3] == 0x38)
+            return "image/gif";
+
+        // WebP: 52 49 46 46 ... 57 45 42 50
+        if (data.Length >= 12 &&
+            data[0] == 0x52 && data[1] == 0x49 && data[2] == 0x46 && data[3] == 0x46 &&
+            data[8] == 0x57 && data[9] == 0x45 && data[10] == 0x42 && data[11] == 0x50)
+            return "image/webp";
+
+        return "application/octet-stream";
+    }
+}

OpenBioCardServer/Utilities/Mappers/ClassicMapper.cs

@@ -35,12 +35,14 @@ public static ClassicProfile ToClassicProfile(ProfileEntity profile)
             Gallery = profile.Gallery.Select(ToClassicGalleryItem).ToList()
         };
     }
-
-    private static string AssetToString(AssetType type, string? text, byte[]? data) => type switch
+    
+    public static string AssetToString(AssetType type, string? text, byte[]? data) => type switch
     {
         AssetType.Text => text ?? string.Empty,
         AssetType.Remote => text ?? string.Empty,
-        AssetType.Image => data != null ? $"data:image/png;base64,{Convert.ToBase64String(data)}" : string.Empty,
+        AssetType.Image => data != null 
+            ? $"data:{ImageHelper.DetectMimeType(data)};base64,{Convert.ToBase64String(data)}" 
+            : string.Empty,
         _ => string.Empty
     };