FileTypeChecker 1.0.0

dotnet add package FileTypeChecker --version 1.0.0
NuGet\Install-Package FileTypeChecker -Version 1.0.0
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="FileTypeChecker" Version="1.0.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add FileTypeChecker --version 1.0.0
#r "nuget: FileTypeChecker, 1.0.0"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install FileTypeChecker as a Cake Addin
#addin nuget:?package=FileTypeChecker&version=1.0.0

// Install FileTypeChecker as a Cake Tool
#tool nuget:?package=FileTypeChecker&version=1.0.0

File Type Checker

File Type Checker is a .Net file identification library allowing developers to the file's magic numbers/identifying bytes against a whitelist.

The purpose of this code is to make it easier for people to add better file security functionality to their projects via a NuGet package.

Usage

Using an IoC container, register the instance in the container

new List<FileType>
{
    new FileType("Portable Network Graphic", ".png",
        new ExactFileTypeMatcher(new byte[] {0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A})),
    new FileType("JPEG", ".jpg",
        new FuzzyFileTypeMatcher(new byte?[] {0xFF, 0xD, 0xFF, 0xE0, null, null, 0x4A, 0x46, 0x49, 0x46, 0x00})),
    new FileType("Portable Document Format", ".pdf", new RangeFileTypeMatcher(new ExactFileTypeMatcher(new byte[] { 0x25, 0x50, 0x44, 0x46 }), 1019))
}

Register the FileTypeChecker concrete implementation to the IFileTypeChecker interface. Wherever you need the checker, dependency inject it and use it like below.

    // pdf is a stream containing a PDF
    var fileType = checker.GetFileType(pdf);

Background

I have seen too many projects allow file uploads any the only validation that occurs is the filename extension. This project exists because there needs to be a plug and play library that facilites mitigating this security issue.

File Magic Number Resources

For a list of file magic numbers, I have found these sites to be useful.

Credits

Based on mjolka's answer to the Stack Overflow question Guessing a file type based on its content.

This repo is forked from https://github.com/mjolka/filetypes and the original code can be found in the "original" branch (preserving for posterity). I have changed the namespaces/project name to better describe the purpose.

Product Compatible and additional computed target framework versions.
.NET Framework net45 is compatible.  net451 was computed.  net452 was computed.  net46 was computed.  net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

This package has no dependencies.

NuGet packages

This package is not used by any NuGet packages.

GitHub repositories

This package is not used by any popular GitHub repositories.

Version Downloads Last updated
1.0.0 16,109 11/17/2017