Re: Multipart Form - Ascertain File Type
This WebDNA talk-list message is from 2007
It keeps the original formatting.
numero = 68738
interpreted = N
texte = Tana Adams wrote: > I was wondering if anyone knew how to ascertain what type of file was being > uploaded when using a multipart form. I'm trying to create a file upload > that will only allow a .txt file to be uploaded. AFAICT, this is impossible to do on the front end. In other words, the multipart MIME upload doesn't have any mechanism to validate the file contents when uploaded. That doesn't mean you can't validate the file after the fact, and simply delete anything that doesn't meet whatever criteria you like (too large, not a JPEG, not named .txt, etc). Be aware that trying to determine what the file contains using only the filename (especially extension) is fraught with danger and pitfalls. One of the results of M$loth's infinite stupidity is the constant issue with e-mail attachments of the form innocuous_file.txt.exe, which based on default (read: STUPID) Windows default is displayed as innocuous_file.txt when in actuality, it is a worm/virus/rootkit... John -- John Peacock Director of Information Research and Technology Rowman & Littlefield Publishing Group 4501 Forbes Boulevard Suite H Lanham, MD 20706 301-459-3366 x.5010 fax 301-429-5748 ------------------------------------------------------------- This message is sent to you because you are subscribed to the mailing list
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Associated Messages, from the most recent to the oldest:
Tana Adams wrote: > I was wondering if anyone knew how to ascertain what type of file was being > uploaded when using a multipart form. I'm trying to create a file upload > that will only allow a .txt file to be uploaded. AFAICT, this is impossible to do on the front end. In other words, the multipart MIME upload doesn't have any mechanism to validate the file contents when uploaded. That doesn't mean you can't validate the file after the fact, and simply delete anything that doesn't meet whatever criteria you like (too large, not a JPEG, not named .txt, etc). Be aware that trying to determine what the file contains using only the filename (especially extension) is fraught with danger and pitfalls. One of the results of M$loth's infinite stupidity is the constant issue with e-mail attachments of the form innocuous_file.txt.exe, which based on default (read: STUPID) Windows default is displayed as innocuous_file.txt when in actuality, it is a worm/virus/rootkit... John -- John Peacock Director of Information Research and Technology Rowman & Littlefield Publishing Group 4501 Forbes Boulevard Suite H Lanham, MD 20706 301-459-3366 x.5010 fax 301-429-5748 ------------------------------------------------------------- This message is sent to you because you are subscribed to the mailing list . To unsubscribe, E-mail to: To switch to the DIGEST mode, E-mail to Web Archive of this list is at: http://webdna.smithmicro.com/
John Peacock
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