s += ":" + escape(u.password, encodeUserPassword)
	}
	return s
}

// Maybe rawURL is of the form scheme:path.
// (Scheme must be [a-zA-Z][a-zA-Z0-9+.-]*)
// If so, return scheme, path; else return "", rawURL.
func getScheme(rawURL string) (scheme, path string, err error) {
	for i := 0; i < len(rawURL); i++ {
		c := rawURL[i]
		switch {
		case 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z':
		// do nothing

	// and the path will end up in req.URL.Path, where it needs to be in order for
	// RPC to work.
	justAuthority := req.Method == "CONNECT" && !strings.HasPrefix(rawurl, "/")
	if justAuthority {
		rawurl = "http://" + rawurl
	}

	if req.URL, err = url.ParseRequestURI(rawurl); err != nil {
		return nil, err
	}

	if justAuthority {
		// Strip the bogus "http://" back off.
		req.URL.Scheme = ""
	}