// prefixed by 'proto='. The match is case-insensitive.
	protoRegex = regexp.MustCompile(`(?i)^(;|,| )+(?:proto=)(https|http)`)
)

// GetSourceScheme retrieves the scheme from the X-Forwarded-Proto and RFC7239
// Forwarded headers (in that order).
func GetSourceScheme(r *http.Request) string {
	var scheme string

	// Retrieve the scheme from X-Forwarded-Proto.
	if proto := r.Header.Get(xForwardedProto); proto != "" {

	}
	for _, v := range headers {
		req := &http.Request{
			Header: http.Header{
				v.key: []string{v.val},
			},
		}
		res := GetSourceScheme(req)
		if res != v.expected {
			t.Errorf("wrong header for %s: got %s want %s", v.key, res,
				v.expected)
		}
	}
}

// TestGetSourceIP - check the source ip of a request is parsed correctly.