func hostInfo()

in control.go [132:188]
47 lines of code
13 McCabe index (conditional complexity)

func hostInfo(addr string, defaultPort int) ([]*HostInfo, error) {
	var port int
	host, portStr, err := net.SplitHostPort(addr)
	if err != nil {
		host = addr
		port = defaultPort
	} else {
		port, err = strconv.Atoi(portStr)
		if err != nil {
			return nil, err
		}
	}

	var hosts []*HostInfo

	// Check if host is a literal IP address
	if ip := net.ParseIP(host); ip != nil {
		h, err := NewHostInfo(ip, port)
		if err != nil {
			return nil, err
		}
		hosts = append(hosts, h)
		return hosts, nil
	}

	// Look up host in DNS
	ips, err := LookupIP(host)
	if err != nil {
		return nil, err
	} else if len(ips) == 0 {
		return nil, fmt.Errorf("no IP's returned from DNS lookup for %q", addr)
	}

	// Filter to v4 addresses if any present
	if hostLookupPreferV4 {
		var preferredIPs []net.IP
		for _, v := range ips {
			if v4 := v.To4(); v4 != nil {
				preferredIPs = append(preferredIPs, v4)
			}
		}
		if len(preferredIPs) != 0 {
			ips = preferredIPs
		}
	}

	for _, ip := range ips {
		h, err := NewHostInfo(ip, port)
		if err != nil {
			return nil, err
		}

		hosts = append(hosts, h)
	}

	return hosts, nil
}