public static bool IsImage(this HttpPostedFileBase postedFile, int ImageMaxiMumBytes)
{
if (postedFile.ISValidObject() && ImageMaxiMumBytes <= postedFile.ContentLength)
{
//-------------------------------------------
// Check the image mime types
//-------------------------------------------
if (postedFile.ContentType.ToLower() != "image/jpg" &&
postedFile.ContentType.ToLower() != "image/jpeg" &&
postedFile.ContentType.ToLower() != "image/pjpeg" &&
postedFile.ContentType.ToLower() != "image/gif" &&
postedFile.ContentType.ToLower() != "image/x-png" &&
postedFile.ContentType.ToLower() != "image/png")
{
return(false);
}
//-------------------------------------------
// Check the image extension
//-------------------------------------------
if (Path.GetExtension(postedFile.FileName).ToLower() != ".jpg" &&
Path.GetExtension(postedFile.FileName).ToLower() != ".png" &&
Path.GetExtension(postedFile.FileName).ToLower() != ".gif" &&
Path.GetExtension(postedFile.FileName).ToLower() != ".jpeg")
{
return(false);
}
//-------------------------------------------
// Attempt to read the file and check the first bytes
//-------------------------------------------
try
{
if (!postedFile.InputStream.CanRead)
{
return(false);
}
//------------------------------------------
//check whether the image size exceeding the limit or not
//------------------------------------------
if (postedFile.ContentLength < ImageMaxiMumBytes)
{
return(false);
}
byte[] buffer = new byte[ImageMaxiMumBytes];
postedFile.InputStream.Read(buffer, 0, ImageMaxiMumBytes);
string content = System.Text.Encoding.UTF8.GetString(buffer);
if (Regex.IsMatch(content, @"<script|<html|<head|<title|<body|<pre|<table|<a\s+href|<img|<plaintext|<cross\-domain\-policy",
RegexOptions.IgnoreCase | RegexOptions.CultureInvariant | RegexOptions.Multiline))
{
return(false);
}
}
catch (Exception)
{
return(false);
}
//-------------------------------------------
// Try to instantiate new Bitmap, if .NET will throw exception
// we can assume that it's not a valid image
//-------------------------------------------
try
{
using (var bitmap = new System.Drawing.Bitmap(postedFile.InputStream))
{
}
}
catch (Exception)
{
return(false);
}
finally
{
postedFile.InputStream.Position = 0;
}
return(true);
}
return(false);
}
