Function AddressToUpstream

upstream/upstream.go:188–217

AddressToUpstream converts addr to an Upstream using the specified options. addr can be either a URL, or a plain address, either a domain name or an IP. - 1.2.3.4 or 1.2.3.4:4321 for plain DNS using IP address; - udp://5.3.5.3:53 or 5.3.5.3:53 for plain DNS using IP address; - udp://name.server:53

(addr string, opts *Options)

//
// TODO(e.burkov):  Clone opts?
func AddressToUpstream(addr string, opts *Options) (u Upstream, err error) {
	if opts == nil {
		opts = &Options{}
	}

	if opts.Logger == nil {
		opts.Logger = slog.Default()
	}

	var uu *url.URL
	if strings.Contains(addr, "://") {
		uu, err = url.Parse(addr)
		if err != nil {
			return nil, fmt.Errorf("failed to parse %s: %w", addr, err)
		}
	} else {
		uu = &url.URL{
			Scheme: "udp",
			Host:   addr,
		}
	}

	err = validateUpstreamURL(uu)
	if err != nil {
		// Don't wrap the error, because it's informative enough as is.
		return nil, err
	}

	return urlToUpstream(uu, opts)
}

// validateUpstreamURL returns an error if the upstream URL is not valid.
func validateUpstreamURL(u *url.URL) (err error) {