FileTypeChecker 1.0.0
dotnet add package FileTypeChecker --version 1.0.0
NuGet\Install-Package FileTypeChecker -Version 1.0.0
<PackageReference Include="FileTypeChecker" Version="1.0.0" />
paket add FileTypeChecker --version 1.0.0
#r "nuget: FileTypeChecker, 1.0.0"
// 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.
- https://www.garykessler.net/library/file_sigs.html
- http://filext.com/
- https://en.wikipedia.org/wiki/List_of_file_signatures
- https://asecuritysite.com/forensics/magic
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 | Versions 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. |
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 | 16,584 | 11/17/2017 |