middleware/content_charset.go
func contentEncoding(ce string, charsets ...string) bool {
	_, ce = split(strings.ToLower(ce), ";")
	_, ce = split(ce, "charset=")
	ce, _ = split(ce, ";")
	for _, c := range charsets {
		if ce == c {
			return true
		}
	}

	return false
}
func contentEncoding(ce string, charsets ...string) bool {
	_, ce = split(strings.ToLower(ce), ";")
	_, ce = split(ce, "charset=")
	ce, _ = split(ce, ";")
	for _, c := range charsets {
		if ce == c {
			return true
		}
	}

	return false
}
// Check the content encoding against a list of acceptable values.