| 26 | } |
| 27 | |
| 28 | func (c *DNSClient) Exchange(m *dns.Msg) (*dns.Msg, error) { |
| 29 | conn, err := DialUDP("udp", "", c.Server) |
| 30 | if err != nil { |
| 31 | return nil, err |
| 32 | } |
| 33 | defer conn.Close() |
| 34 | if err := conn.SetDeadline(time.Now().Add(time.Duration(60) * time.Second)); err != nil { |
| 35 | return nil, err |
| 36 | } |
| 37 | b, err := m.Pack() |
| 38 | if err != nil { |
| 39 | return nil, err |
| 40 | } |
| 41 | if _, err := conn.Write(b); err != nil { |
| 42 | return nil, err |
| 43 | } |
| 44 | b = make([]byte, 1024) |
| 45 | i, err := conn.Read(b) |
| 46 | if err != nil { |
| 47 | return nil, err |
| 48 | } |
| 49 | r := &dns.Msg{} |
| 50 | if err := r.Unpack(b[:i]); err != nil { |
| 51 | return nil, err |
| 52 | } |
| 53 | return r, nil |
| 54 | } |
| 55 | |
| 56 | // if no AAAA, return nil |
| 57 | func (c *DNSClient) AAAA(domain string) (net.IP, error) { |