XTLS/Xray-core · error

invalid host + host

Error message

invalid host + host

What it means

Thrown by Realm.Build() when the parsed Realm URL has an empty host component. After scheme validation, u.Hostname() must yield a non-empty value; a URL like 'realm:///path' (no authority) fails here. The host is a required part of the Realm endpoint address.

Source

Thrown at infra/conf/transport_finalmask.go:845

	var tlsConfig *tls.Config

	u, err := url.Parse(c.Url)
	if err != nil {
		return nil, err
	}

	switch u.Scheme {
	case "realm":
		scheme = "https"
	case "realm+http":
		scheme = "http"
	default:
		return nil, errors.New("invalid scheme", u.Scheme)
	}

	host = u.Hostname()
	if host == "" {
		return nil, errors.New("invalid host", host)
	}

	port = u.Port()
	if port == "" {
		port = "443"
		if scheme == "http" {
			port = "80"
		}
	}

	token, err = url.PathUnescape(u.User.String())
	if err != nil {
		return nil, err
	}
	if token == "" {
		return nil, errors.New("invalid token", token)
	}

View on GitHub (pinned to 7d214f8b09)

Solutions

1. Include an explicit host: 'realm://token@host:port/id'.
2. Log or echo the final URL string before running the core to catch empty substitutions.
3. Validate the URL with net/url in a pre-flight check (see defense).

Example fix

// before
"url": "realm://mytoken@/v1"
// after
"url": "realm://mytoken@signal.example.com:8443/v1"

u, _ := url.Parse(raw)
if u.Hostname() == "" {
    return fmt.Errorf("realm url is missing a host")
}

When it happens

Trigger: Passing 'realm:///id' (missing authority), a URL whose host is only userinfo ('realm://token@/id'), or a value that lost its host during string concatenation/template interpolation.

Common situations: Environment-variable substitution producing an empty host; hand-built URL strings with a double '//' after the scheme; copying a share link and deleting the hostname.

Related errors

• invalid scheme + u.Scheme
• invalid token + token
• invalid id + id
• bridge tag is empty
• bridge domain is empty

AI-assisted analysis of XTLS/Xray-core@7d214f8b09 (2026-08-15). Data as JSON: /api/errors/b44e47b2d32cfbef. Report an issue: GitHub.