Method ResolveAddr

internal/resolver/resolver.go:38–84

ResolveAddr resolves an IP address to a hostname, with caching

(addr string)

// ResolveAddr resolves an IP address to a hostname, with caching
func (r *Resolver) ResolveAddr(addr string) string {
	// check cache first (unless caching is disabled)
	if !r.noCache {
		r.mutex.RLock()
		if cached, exists := r.cache[addr]; exists {
			r.mutex.RUnlock()
			return cached
		}
		r.mutex.RUnlock()
	}

	// parse ip to validate it
	ip := net.ParseIP(addr)
	if ip == nil {
		return addr
	}

	// perform resolution with timeout
	start := time.Now()
	ctx, cancel := context.WithTimeout(context.Background(), r.timeout)
	defer cancel()

	names, err := net.DefaultResolver.LookupAddr(ctx, addr)

	resolved := addr
	if err == nil && len(names) > 0 {
		resolved = names[0]
		// remove trailing dot if present
		if len(resolved) > 0 && resolved[len(resolved)-1] == '.' {
			resolved = resolved[:len(resolved)-1]
		}
	}

	elapsed := time.Since(start)
	if debugTiming && elapsed > 50*time.Millisecond {
		fmt.Fprintf(os.Stderr, "[timing] slow DNS lookup: %s -> %s (%v)\n", addr, resolved, elapsed)
	}

	// cache the result (unless caching is disabled)
	if !r.noCache {
		r.mutex.Lock()
		r.cache[addr] = resolved
		r.mutex.Unlock()
	}

	return resolved
}

// ResolvePort resolves a port number to a service name
func (r *Resolver) ResolvePort(port int, proto string) string {