asyncdns.go

// Package asyncdns is a terrible, inflexible, async reverse-DNS lookup tool
package asyncdns

import "fmt"
import "net"

type Wibble struct {
	host     string // IP address in theory
	hostname string
	err      error

	hostnameChan chan string
	errChan      chan error
}

func NewWibble(host string) *Wibble {
	var wibble = new(Wibble)
	wibble.host = host
	wibble.hostnameChan = make(chan string)
	wibble.errChan = make(chan error)

	go wibble.lookup()

	return wibble
}

func (wibble *Wibble) lookup() {
	var names, err = net.LookupAddr(wibble.host)

	if err != nil {
		wibble.errChan <- err
	} else if len(names) > 0 {
		wibble.hostnameChan <- names[0]
	}
}

func (wibble *Wibble) Host() string {
	return wibble.host
}

func (wibble *Wibble) Describe() string {
	if wibble.hostname != "" {
		return wibble.hostname
	}

	if wibble.err != nil {
		return fmt.Sprintf("%s (%s)", wibble.host, wibble.err)
	}

	select {
	case hostname := <-wibble.hostnameChan:
		wibble.hostname = hostname
		return wibble.Describe()
	case err := <-wibble.errChan:
		wibble.err = err
		return wibble.Describe()
	default:
		return fmt.Sprintf("%s (looking up)", wibble.host)
	}
}