Advanced ASP.NET Core 3 Security by Scott Norberg

Author:Scott Norberg
Language: eng
Format: epub
ISBN: 9781484260142
Publisher: Apress

byte[] fileBytes;

var asFile = (IFormFile)value;

using (var stream = asFile.OpenReadStream())

{

fileBytes = new byte[stream.Length];

for (int i = 0; i < stream.Length; i++)

{

fileBytes[i] = (byte)stream.ReadByte();

}

}

var ext = System.IO.Path.GetExtension(asFile.FileName);

switch (ext)

{

case ".jpg":

case ".jpeg":

//If the first three bytes don't match the expected,

//fail the check

if (fileBytes[0] != 255 ||

fileBytes[1] != 216 ||

fileBytes[2] != 255)

return new ValidationResult("Image appears not " +

"to be in jpg format. Please try another.");

//If the fourth byte doesn't match one of the four

//expected values, fail the check

else if (fileBytes[3] != 219 &&

fileBytes[3] != 224 &&

fileBytes[3] != 238 &&

fileBytes[3] != 225)

return new ValidationResult("Image appears not " +

"to be in jpg format. Please try another.");

else

//All expected bytes match

return ValidationResult.Success;

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