Validating content type of files in file upload

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Hi,

In my web page there is a file upload control. I want to check whether the uploaded file type is of .wav format only. I tried with the following code

C#

HttpPostedFile objHPF = objHFC["fldUpload"];
string contentType = objHPF.ContentType.Split('/')[1].ToLower();

and checked whether the contenttype="wav"...

But when i uploaded the same file in two browsers(FF & Chrome) i got X-WAV in FF and WAV as content type in chrome .... So what can i do to check the content type and why this happened? Pls help.. Thanks in advance

Posted 17-Sep-13 23:31pm

Arjun Menon U.K

Updated 17-Sep-13 23:35pm

v2

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Thanks7872 · Answer 1 · 2013-09-17T23:38:00

Solution 1

All you need is C# Path.GetExtension[^]

See this also

Check type of uploaded file[^]

Regards..:)

Posted 17-Sep-13 23:38pm

Thanks7872

Updated 17-Sep-13 23:50pm

v2

Comments

Arjun Menon U.K 18-Sep-13 5:41am

If i am right ,this wont get the accurate data because if i rename the file name as ABC.gif where the actual content type is png, the above code returns gif instead of png. Correct me if i am wrong

Thanks7872 18-Sep-13 5:51am

Yes.Refer to updated one.

Arjun Menon U.K 18-Sep-13 6:03am

you mean this one
static bool IsTxtFile(string f)
{
return f != null &&
f.EndsWith(".txt", StringComparison.Ordinal);
}

Arjun Menon U.K 18-Sep-13 6:10am

how can i find the content type, like if the pass the file name i must get the content type

Thomas ktg · Answer 2 · 2013-09-17T23:43:00

Solution 2

One more thing is that you can use regular expression validation control in ASP.NET to validate the extension of the file to be uploaded.

Refer this link.

http://www.c-sharpcorner.com/UploadFile/99bb20/validation-for-file-upload-control-in-Asp-Net/[^]

Use this link to get better idea to the file type
http://stackoverflow.com/questions/15300567/alternative-to-findmimefromdata-method-in-urlmon-dll-one-which-has-more-mime-typ[^]

Posted 17-Sep-13 23:43pm

Thomas ktg

Updated 18-Sep-13 0:09am

v2

Comments

Arjun Menon U.K 18-Sep-13 5:46am

The comparing data is the problem.. One browser returns wav and other x-wav for same file... so how to compare?

Thomas ktg 18-Sep-13 5:51am

use the regular expression accordingly
for example you know the file extension for different browsers. Use all the extensions in the expression. This will validate based on the extensions returned by the different browsers.
ValidationExpression=/^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.wav|.WAV|.x-wav|X-WAV)$/

Arjun Menon U.K 18-Sep-13 5:53am

mmm that's the only way i have in mind too .. to check whether its wav/x-wav but it seems not a good logic coz god knows what else can come for a wav file next time

Thomas ktg 18-Sep-13 6:10am

Yes.Of-course it is obvious. See the updated solution.