Function valuesFromHeader

middleware/extractor.go:122–161

valuesFromHeader returns a functions that extracts values from the request header. valuePrefix is parameter to remove first part (prefix) of the extracted value. This is useful if header value has static prefix like `Authorization: ` where part that we want to

(header string, valuePrefix string, limit uint)

// is `Basic `. In case of JWT tokens `Authorization: Bearer <token>` prefix is `Bearer `.
// If prefix is left empty the whole value is returned.
func valuesFromHeader(header string, valuePrefix string, limit uint) ValuesExtractor {
	prefixLen := len(valuePrefix)
	// standard library parses http.Request header keys in canonical form but we may provide something else so fix this
	header = textproto.CanonicalMIMEHeaderKey(header)
	if limit == 0 {
		limit = 1
	}
	return func(c *echo.Context) ([]string, ExtractorSource, error) {
		values := c.Request().Header.Values(header)
		if len(values) == 0 {
			return nil, ExtractorSourceHeader, errHeaderExtractorValueMissing
		}

		i := uint(0)
		result := make([]string, 0)
		for _, value := range values {
			if prefixLen == 0 {
				result = append(result, value)
				i++
				if i >= limit {
					break
				}
			} else if len(value) > prefixLen && strings.EqualFold(value[:prefixLen], valuePrefix) {
				result = append(result, value[prefixLen:])
				i++
				if i >= limit {
					break
				}
			}
		}

		if len(result) == 0 {
			if prefixLen > 0 {
				return nil, ExtractorSourceHeader, errHeaderExtractorValueInvalid
			}
			return nil, ExtractorSourceHeader, errHeaderExtractorValueMissing
		}
		return result, ExtractorSourceHeader, nil
	}
}

// valuesFromQuery returns a function that extracts values from the query string.
func valuesFromQuery(param string, limit uint) ValuesExtractor {