Validate files based on mime types, file extensions and magic byte sequences.
$ dotnet add package MagicBytesValidatorRecognize file types from Streams or IFormFiles using MIME types or file extensions and validate them against the magic bytes according to the file types.
The existing IFileTypes can be expanded in various ways.
Install-Package MagicBytesValidator -Version 2.1.2
dotnet add package MagicBytesValidator --version 2.1.2
<PackageReference Include="MagicBytesValidator" Version="2.1.2" />
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();
FileByteFilter: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
])
}
)FileByteFilters with specific offset checks: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 IFileTypes, e.g.
mapping.Register(typeof(CustomFileType).Assembly);. This will register all IFileTypes 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.
| FileType | Extensions | MIME Types |
|---|---|---|
| AIF | aif, aiff, aifc | audio/x-aiff |
| BIN | bin, file, com, class, ini | application/octet-stream |
| BMP | bmp | image/bmp |
| CAB | cab | application/vnd.ms-cab-compressed, application/x-cab-compressed |
| DOC | doc, dot | application/msword |
| DOCX | docx | application/vnd.openxmlformats-officedocument.wordprocessingml.document |
| DXR | dxr, dcr, dir | application/x-director |
| EXE | exe, com, dll, drv, pif, qts, qtx , sys, acm, ax, cpl, fon, ocx, olb, scr, vbx, vxd, mui, iec, ime, rs, tsp, efi | application/x-dosexec, application/x-msdos-program |
| GIF | gif | image/gif |
| GZ | gz | application/gzip |
| HEIC | heic, heif | image/heic, image/heif |
| ICO | ico | image/x-icon |
| JPG | jpg, jpeg, jpe, jif, jfif, jfi | image/jpeg |
| MIDI | midi, mid | audio/x-midi |
| MP3 | mp3 | audio/mpeg |
| MP4 | mp4 | video/mp4 |
| MPG | mpg, mpeg, mpe, m2p, vob | video/mpeg |
| ODP | odp | application/vnd.oasis.opendocument.presentation |
| ODS | ods | application/vnd.oasis.opendocument.spreadsheet |
| ODT | odt | application/vnd.oasis.opendocument.text |
| OGV | ogv, ogg, oga | video/ogg |
| PBM | pbm | image/x-portable-bitmap |
| application/pdf | ||
| PGM | pgm | image/x-portable-graymap |
| PNG | png | image/png |
| PPM | ppm | image/x-portable-pixmap |
| PPT | ppt, ppz, pps, pot | application/mspowerpoint, application/vnd.ms-powerpoint |
| PPTX | pptx | application/vnd.openxmlformats-officedocument.presentationml.presentation |
| RAR | rar | application/vnd.rar, application/x-rar-compressed |
| RPM | rpm | application/x-rpm, application/x-redhat-package-manager |
| RTF | rtf | application/rtf |
| SND | snd, au | audio/basic |
| SVG | svg, svgz | image/svg+xml |
| SWF | swf | application/x-shockwave-flash |
| 3GP | 3gp | video/3gpp |
| TIF | tif, tiff | image/tiff |
| TSV | ts, tsv, tsa, mpg, mpeg | video/mp2t |
| TXT | txt | text/plain |
| WEBM | mkv, mka, mks, mk3d, webm | video/webm |
| XLS | xls, xla | application/msexcel |
| XLSX | xlsx | application/vnd.openxmlformats-officedocument.spreadsheetml.sheet |
| XML | xml | application/xml, text/xml |
| Z | z | application/x-compress |
| ZIP | zip | application/zip, application/x-zip-compressed |
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