Validate files based on mime types, file extensions and magic byte sequences.
$ dotnet add package MagicBytesValidatorRecognize filetypes from Streams or IFormfiles using mime types or file extensions and validate them against the magic bytes according to the filetypes.
The existing FileTypes can be expanded in various ways.
Install-Package MagicBytesValidator -Version 2.0.2
dotnet add package MagicBytesValidator --version 2.0.2
<PackageReference Include="MagicBytesValidator" Version="2.0.2" />
var validator = new MagicBytesValidator.Services.Validator();
var formFileTypeProvider = new MagicBytesValidator.Services.Http.FormFileTypeProvider();
var streamFileTypeProvider = new MagicBytesValidator.Services.Streams.StreamFileTypeProvider();
var pngFileType = validator.Mapping.FindByExtension("png");
var pdfFileType = validator.Mapping.FindByMimeType("application/pdf");
var fileType = await formFileTypeProvider.FindValidatedTypeAsync(formFile, null, CancellationToken.None);
var fileType = await streamFileTypeProvider.TryFindUnambiguousAsync(fileStream, CancellationToken.None);
var isValid = await validator.IsValidAsync(memoryStream, fileType, CancellationToken.None);
// use the validator:
var mapping = validator.Mapping;
// use the formFileTypeProvider:
var mapping = formFileTypeProvider.Mapping;
// or create a new instance of the mapping:
var mapping = new MagicBytesValidator.Services.Mapping();
mapping.Register(
new FileByteFilter(
"traperto/trp", // mime type
new[] { "trp" } // file extensions
) {
// magic byte sequences
StartsWith([
0x78, 0x6c, 0x2f, 0x5f, 0x72, 0x65
])
.EndsWith([
0xFF, 0xFF
])
}
)mapping.Register(
new FileByteFilter(
"traperto/trp", // mime type
new[] { "trp" } // file extensions
) {
// magic byte sequences
Specific(new ByteCheck(512, [0xFD]));
}
)ByteCheck allows for negative offset values to look for a specific offset counting from the end of file
mapping.Register(listOfFileTypes);You can also create variants of IFileType and register them by passing the Assembly of the new FileTypes, e.g.
mapping.Register(typeof(CustomFileType).Assembly);. This will register all FileTypes of the given Assembly that are also
not abstract and have an empty constructor!
public class CustomFileType : FileTypeWithStartSequences
{
public CustomFileType() : base(
"traperto/trp", // mime type
new[] { "trp" }, // file extensions
new[] { // magic byte sequences
new byte[] { 0x74, 0x72, 0x61, 0x70, 0x65, 0x72, 0x74, 0x6f }
}
)
{
}
}
var assembly = typeof(CustomFileType).Assembly;
_mapping.Register(assembly);There's a CLI tool (MagicBytesValidator.CLI) which can be used to determine MIME types for a local file by calling the following command.
dotnet run --project MagicBytesValidator.CLI -- [PATH]This can be useful when debugging or validating newly added FileTypes.
| Mimetype | Extension | Magicbytes (decimal) |
|---|---|---|
| audio/x-pn-realaudio-plugin | rpm | 237 171 238 219 |
| application/octet-stream | bin file com class ini |
|
| video/3gpp | 3gp | 102 116 121 112 51 103 |
| image/x-icon | ico | 0 0 1 0 |
| image/gif | gif |
|
| image/tiff | tif tiff |
|
| image/jpeg | jpg jpeg jpe |
|
| image/png | png | 137 80 78 71 13 10 26 10 |
| video/ogg | ogg ogv | 79 103 103 83 |
| audio/basic | snd au |
|
| application/dsptype | tsp | 77 90 |
| text/plain | txt |
|
| application/zip | zip | 80 75 3 4 |
| application | docx xlsx | 80 75 7 8 |
| application/vnd.oasis.opendocument.presentation | odp | 80 75 7 8 |
| application/vnd.oasis.opendocument.spreadsheet | ods | 80 75 7 8 |
| application/vnd.oasis.opendocument.text | odt | 80 75 7 8 |
| audio/mpeg | mp3 | 73 68 51 |
| image/bmp | bmp | 66 77 |
| audio/x-midi | midi mid | 77 84 104 100 |
| application/msword | doc dot | 208 207 17 224 161 177 26 255 |
| application/msexcel | xlx xla | 208 207 17 224 161 177 26 255 |
| application/mspowerpoint | ppt ppz pps pt | 208 207 17 224 161 177 26 225 |
| application/gzip | gz | 31 139 |
| video/webm | webm | 26 69 223 163 |
| application/rtf | rtf | 123 92 114 116 102 49 |
| text/tab-separated-values | tsv | 71 |
| video/mpeg | mpg mpeg mpe |
|
| video/mp4 | mp4 |
|
| image/x-portable-bitmap | pbm | 80 49 10 |
| image/x-portable-graymap | pgm | 80 50 10 |
| image/x-portable-pixmap | ppm | 80 51 10 |
| application/pdf | multiple |
MIT License
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