Question

what is the default encoding one should use to decode multipart/form-data if no charset is given? RFC2388 states:

4.5 Charset of text in form data

Each part of a multipart/form-data is supposed to have a content-
type. In the case where a field element is text, the charset
parameter for the text indicates the character encoding used.

For example, a form with a text field in which a user typed ‘Joe owes
<eu>100’ where <eu> is the Euro symbol might have form data returned
as:

--AaB03x
content-disposition: form-data; name="field1"
content-type: text/plain;charset=windows-1250
content-transfer-encoding: quoted-printable>>

Joe owes =80100.
--AaB03x

In my case, the charset isn’t set and I don’t know how to decode the data within that text/plain section. As I do not want to enforce something that isn’t standard behavior I’m asking what the expected behavior in this case is. The RFC does not seem to explain this so I’m kinda lost.

Thank you!

Answer 1

The default charset for HTTP 1.1 is ISO-8859-1 (Latin1), I would guess that this also applies here.

3.7.1 Canonicalization and Text Defaults

–snip–

The “charset” parameter is used with some media types to define the character set (section 3.4) of the data. When no explicit charset parameter is provided by the sender, media subtypes of the “text” type are defined to have a default charset value of “ISO-8859-1” when received via HTTP. Data in character sets other than “ISO-8859-1” or its subsets MUST be labeled with an appropriate charset value. See section 3.4.1 for compatibility problems.