Method LookupNetIP

dialer/rescache.go:48–89

(ctx context.Context, network, host string)

}

func (r *CachingResolver) LookupNetIP(ctx context.Context, network, host string) ([]netip.Addr, error) {
	if addr, err := netip.ParseAddr(host); err == nil {
		// literal IP address, just do unmapping
		return r.next.LookupNetIP(ctx, network, addr.Unmap().String())
	}

	host = strings.ToLower(host)
	key := resolverCacheKey{
		network: network,
		host:    host,
	}

	res, ok := r.cache.GetValidOrDelete(key)
	if !ok {
		v, _, _ := r.sf.Do(key.network+":"+key.host, func() (any, error) {
			ctx, cl := context.WithTimeout(context.Background(), r.timeout)
			defer cl()
			res, err := r.next.LookupNetIP(ctx, key.network, key.host)
			for i := range res {
				res[i] = res[i].Unmap()
			}
			setTTL := r.negTTL
			if err == nil {
				setTTL = r.posTTL
			}
			item := &resolverCacheValue{
				expires: time.Now().Add(setTTL),
				addrs:   res,
				err:     err,
			}
			r.cache.Set(key, item)
			return item, nil
		})
		res = v.(*resolverCacheValue)
	}

	if res.err != nil {
		return nil, res.err
	}

	return res.addrs, nil
}

var _ Resolver = new(CachingResolver)