Function isLoopback

server-source-code/internal/middleware/cors.go:194–208

isLoopback returns true if the host (with or without port) is a loopback address. This allows internal health checks and agent connections that bypass the proxy.

(hostPort string)

// isLoopback returns true if the host (with or without port) is a loopback address.
// This allows internal health checks and agent connections that bypass the proxy.
func isLoopback(hostPort string) bool {
	host := hostPort
	if idx := strings.LastIndex(hostPort, ":"); idx != -1 {
		// Handle IPv6 [::1]:port
		if strings.Contains(hostPort, "]") {
			host = strings.TrimPrefix(hostPort[:strings.Index(hostPort, "]")+1], "[")
			host = strings.TrimSuffix(host, "]")
		} else {
			host = hostPort[:idx]
		}
	}
	host = strings.TrimPrefix(host, "[")
	host = strings.TrimSuffix(host, "]")
	return host == "localhost" || host == "127.0.0.1" || host == "::1" || strings.HasPrefix(host, "127.")
}