func idnaASCII(v string) (string, error) {
if isASCII(v) {
return v, nil
}
// The idna package doesn't do everything from
// https://tools.ietf.org/html/rfc5895 so we do it here.
// TODO(bradfitz): should the idna package do this instead?
v = strings.ToLower(v)
v = width.Fold.String(v)
v = norm.NFC.String(v)
return idna.ToASCII(v)
}
// PunycodeHostPort returns the IDNA Punycode version
// of the provided "host" or "host:port" string.
func PunycodeHostPort(v string) (string, error) {
if isASCII(v) {
return v, nil
}
host, port, err := net.SplitHostPort(v)
if err != nil {
// The input 'v' argument was just a "host" argument,
// without a port. This error should not be returned
// to the caller.
host = v
port = ""
}
host, err = idna.ToASCII(host)
if err != nil {
// Non-UTF-8? Not representable in Punycode, in any
// case.
return "", err
}
if port == "" {
return host, nil
}
return net.JoinHostPort(host, port), nil
}