go-goyave / goyave / 34209356739

97%

master: 97%

Pull #295

github

httputil: fix quality value parsing in ParseMultiValuesHeader

The quality value regex in util/httputil/httputil.go matched everything
located after the first ";" in a header value against
`^q=([01]\.[0-9]{1,3})$`. Anything that did not match fell back to a
priority of 0, which sorts the value last instead of first. Three shapes
allowed by RFC 9110 do not match that regex:
  - optional whitespace after the ";", e.g. "gzip; q=0.9"
  - a quality value with no fraction, e.g. "gzip;q=1"
  - a "q" parameter that is not first, e.g. "text/html;charset=utf-8;q=0.9"

Both callers got the client's preference backwards as a result.
"Accept-Encoding: gzip;q=1, br;q=0.9" made compress.Middleware.getEncoder
return br, and "Accept-Language: en-US;q=0.5, fr-FR; q=0.9" made
lang.Languages.DetectLanguage return en-US.

Walk the parameter list and read the "q" parameter from it instead of
matching the list as a whole, and accept the integer forms of a quality
value. A value with no "q" parameter now has a priority of 1, the RFC
9110 default, which is already what a value with no parameters gets.

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