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islaytitans/MimeTypeAllowed.cs Secret

Created Sep 24, 2015
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Uses the permitted file types and compares the byte array sequence of the uploaded file against them
public FileType MimeTypeAllowed(byte[] file, string fileName, List<FileType> permittedMimeTypes)
FileType uploadedFileType = null;
string extension = Path.GetExtension(fileName) != null
? Path.GetExtension(fileName).ToUpper()
: string.Empty;
var matchedByByte = new List<FileType>();
var matchedByByteAndExtension = new List<FileType>();
foreach (var permittedMimeType in permittedMimeTypes)
int byteCount = permittedMimeType.ByteArray.Count();
if (file.Take(byteCount).SequenceEqual(permittedMimeType.ByteArray))
if (!string.IsNullOrEmpty(permittedMimeType.FileExtension))
if (permittedMimeType.FileExtension.Equals(extension, StringComparison.InvariantCultureIgnoreCase))
matchedByByteAndExtension.Add(new FileType(permittedMimeType.MimeType, file, extension));
matchedByByte.Add(new FileType(permittedMimeType.MimeType, file, extension));
uploadedFileType = matchedByByteAndExtension.Any()
? matchedByByteAndExtension.FirstOrDefault()
: matchedByByte.Any() ? matchedByByte.FirstOrDefault() : null;
return uploadedFileType;
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