boundarymultipartform-data

What are valid characters for creating a multipart form boundary?

In an HTML form post what are valid characters for creating a multipart boundary?

Solution

  • According to RFC 2046, section 5.1.1:

     boundary := 0*69<bchars> bcharsnospace

 bchars := bcharsnospace / " "

 bcharsnospace := DIGIT / ALPHA / "'" / "(" / ")" /
                  "+" / "_" / "," / "-" / "." /
                  "/" / ":" / "=" / "?"

    So it can be between 1 and 70 characters long, consisting of alphanumeric, and the punctuation you see in the list. Spaces are allowed except at the end.