func addCORSDefaults(c *cmdsHttp.ServerConfig) {
	// by default use localhost origins
	if len(c.AllowedOrigins()) == 0 {
		c.SetAllowedOrigins(defaultLocalhostOrigins...)
	}

	// by default, use GET, PUT, POST
	if len(c.AllowedMethods()) == 0 {
		c.SetAllowedMethods("GET", "POST", "PUT")
	}
}

func patchCORSVars(c *cmdsHttp.ServerConfig, addr net.Addr) {

	// we have to grab the port from an addr, which may be an ip6 addr.
	// TODO: this should take multiaddrs and derive port from there.
	port := ""
	if tcpaddr, ok := addr.(*net.TCPAddr); ok {
		port = strconv.Itoa(tcpaddr.Port)
	} else if udpaddr, ok := addr.(*net.UDPAddr); ok {
		port = strconv.Itoa(udpaddr.Port)
	}

	// we're listening on tcp/udp with ports. ("udp!?" you say? yeah... it happens...)
	origins := c.AllowedOrigins()
	for i, o := range origins {
		// TODO: allow replacing <host>. tricky, ip4 and ip6 and hostnames...
		if port != "" {
			o = strings.Replace(o, "<port>", port, -1)
		}
		origins[i] = o
	}
	c.SetAllowedOrigins(origins...)
}

func addCORSFromEnv(c *cmdsHttp.ServerConfig) {
	origin := os.Getenv(originEnvKey)
	if origin != "" {
		log.Warning(originEnvKeyDeprecate)
		if len(c.AllowedOrigins()) == 0 {
			c.SetAllowedOrigins([]string{origin}...)
		}
		c.AppendAllowedOrigins(origin)
	}
}

func addHeadersFromConfig(c *cmdsHttp.ServerConfig, nc *config.Config) {
	log.Info("Using API.HTTPHeaders:", nc.API.HTTPHeaders)

	if acao := nc.API.HTTPHeaders[cmdsHttp.ACAOrigin]; acao != nil {
		c.CORSOpts.AllowedOrigins = acao
	}
	if acam := nc.API.HTTPHeaders[cmdsHttp.ACAMethods]; acam != nil {
		c.CORSOpts.AllowedMethods = acam
	}
	if acac := nc.API.HTTPHeaders[cmdsHttp.ACACredentials]; acac != nil {
		for _, v := range acac {
			c.CORSOpts.AllowCredentials = (strings.ToLower(v) == "true")
		}
	}

	c.Headers = nc.API.HTTPHeaders
}