Uses of content-disposition in an HTTP response header

129
votes

I have found the following asp.net code to be very useful when serving files from a database:

Response.AppendHeader("content-disposition", "attachment; filename=" + fileName);

This lets the user save the file to their computer and then decide how to use it, instead of the browser trying to use the file.

What other things can be done with the content-disposition response header?

5
httphttp-headershttpwebresponsehttpresponsecontent-disposition
Note that your sample code will break if filename contains whitespace or non-ASCII characters. See RFC 6266 for more information. - Julian Reschke
@JulianReschke, What about ASCII characters that are considered non-printable? (0 to 0x1F) - Pacerier
Read RFC 6266 (apart the fact they would be a bad idea to use in a filename; recipients are likely to throw them away anyway) - Julian Reschke
You can use white space, Unicode etc.. if you use double quotes around the name. kb.mozillazine.org/… - Tony BenBrahim
@Ronnie Overby What is Content Disposition? - divy3993

5 Answers

85
votes

Note that RFC 6266 supersedes the RFCs referenced below. Section 7 outlines some of the related security concerns.

The authority on the content-disposition header is RFC 1806 and RFC 2183. People have also devised content-disposition hacking. It is important to note that the content-disposition header is not part of the HTTP 1.1 standard.

The HTTP 1.1 Standard (RFC 2616) also mentions the possible security side effects of content disposition:

15.5 Content-Disposition Issues

RFC 1806 [35], from which the often implemented Content-Disposition
(see section 19.5.1) header in HTTP is derived, has a number of very
serious security considerations. Content-Disposition is not part of
the HTTP standard, but since it is widely implemented, we are
documenting its use and risks for implementors. See RFC 2183 [49]
(which updates RFC 1806) for details.

26
votes

Well, it seems that the Content-Disposition header was originally created for e-mail, not the web. (Link to relevant RFC.)

I'm guessing that web browsers may respond to

Response.AppendHeader("content-disposition", "inline; filename=" + fileName);

when saving, but I'm not sure.

6
votes

Refer to RFC 6266 (Use of the Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)) http://tools.ietf.org/html/rfc6266

6
votes

For asp.net users, the .NET framework provides a class to create a content disposition header: System.Net.Mime.ContentDisposition

Basic usage:

var cd = new System.Net.Mime.ContentDisposition();
cd.FileName = "myFile.txt";
cd.ModificationDate = DateTime.UtcNow;
cd.Size = 100;
Response.AppendHeader("content-disposition", cd.ToString());
2
votes

This header is defined in RFC 2183, so that would be the best place to start reading.

Permitted values are those registered with the Internet Assigned Numbers Authority (IANA); their registry of values should be seen as the definitive source.