repository·master·Indexed 41 days ago
https://github.com/ajmitev/filetypecheckerA .NET Standard 2.0+ library for secure file type validation using magic number (binary signature) detection. It provides the FileTypeValidator class and Stream extension methods to verify files across categories such as Images, Documents, Archives, Audio/Video, and Executables. Includes a companion package, FileTypeChecker.Web, for adding validation attributes to IFormFile models in ASP.NET Core applications.
For ASP.NET Core, use the companion package FileTypeChecker.Web to add validation attributes to your IFormFile models. This allows for automatic validation during model binding.
public class UploadModel
{
[AllowedFileTypes(FileType.Jpeg, FileType.Png)]
[MaxFileSize(5 * 1024 * 1024)] // 5MB
public IFormFile ProfileImage { get; set; }
}You can install FileTypeChecker using various .NET package management tools. The library requires .NET Standard 2.0+.
# Using Package Manager
Install-Package File.TypeChecker# Using .NET CLI
dotnet add package File.TypeChecker<!-- Using PackageReference in .csproj -->
<PackageReference Include="File.TypeChecker" Version="4.2.0" />The library provides extension methods on Stream to quickly check if a file belongs to a specific category (like Images or Documents) or a specific format (like PNG or JPEG).
using (var fileStream = File.OpenRead("image.jpg"))
{
// Check by category
bool isImage = fileStream.IsImage();
bool isDocument = fileStream.IsDocument();
bool isArchive = fileStream.IsArchive();
// Check specific type using generics
bool isPng = fileStream.Is<PortableNetworkGraphic>();
bool isJpeg = fileStream.Is<JointPhotographicExpertsGroup>();
}Use the FileTypeValidator class to identify files by their binary signatures (magic numbers) rather than their extensions. This is useful for verifying that a file is actually what its extension claims it to be.
using (var fileStream = File.OpenRead("document.pdf"))
{
// Check if file type is recognizable
if (FileTypeValidator.IsTypeRecognizable(fileStream))
{
// Get file type information
IFileType fileType = FileTypeValidator.GetFileType(fileStream);
Console.WriteLine($"Type: {fileType.Name}");
Console.WriteLine($"Extension: {fileType.Extension}");
}
}You can extend the library by implementing the FileType class and registering your custom format with the FileTypeValidator. This allows the library to recognize proprietary or niche binary signatures.
// Register your own file type
public class MyCustomType : FileType
{
public override string Name => "My Custom Format";
public override string Extension => "mycustom";
public override string MimeType => "application/x-mycustom";
public override bool IsMatch(byte[] signature, Stream stream)
{
// Implement logic to match your specific binary signature
return signature.Length >= 4 &&
signature[0] == 0x4D && signature[1] == 0x59 &&
signature[2] == 0x43 && signature[3] == 0x54;
}
}
// Use it
FileTypeValidator.RegisterType<MyCustomType>();FileTypeChecker supports over 30 file formats across several categories: