| 8 | ) |
| 9 | |
| 10 | func TestDNSEndpointExchange_MatchesResponseID(t *testing.T) { |
| 11 | ln, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 0}) |
| 12 | if err != nil { |
| 13 | t.Fatalf("ListenUDP: %v", err) |
| 14 | } |
| 15 | defer ln.Close() |
| 16 | |
| 17 | done := make(chan struct{}) |
| 18 | go func() { |
| 19 | defer close(done) |
| 20 | buf := make([]byte, 2048) |
| 21 | n, raddr, err := ln.ReadFromUDP(buf) |
| 22 | if err != nil || n < 2 { |
| 23 | return |
| 24 | } |
| 25 | // Echo a minimal response with the same ID. |
| 26 | resp := make([]byte, 12) |
| 27 | resp[0], resp[1] = buf[0], buf[1] |
| 28 | _, _ = ln.WriteToUDP(resp, raddr) |
| 29 | }() |
| 30 | |
| 31 | e := &DNSEndpoint{Addr: ln.LocalAddr().String()} |
| 32 | payload := make([]byte, 12) |
| 33 | buf := make([]byte, 514) |
| 34 | buf[1] = 0xFF // would have broken the old buggy ID calculation. |
| 35 | |
| 36 | ctx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond) |
| 37 | defer cancel() |
| 38 | |
| 39 | n, err := e.Exchange(ctx, payload, buf) |
| 40 | if err != nil { |
| 41 | t.Fatalf("Exchange error: %v", err) |
| 42 | } |
| 43 | if n < 2 { |
| 44 | t.Fatalf("expected n>=2, got %d", n) |
| 45 | } |
| 46 | |
| 47 | <-done |
| 48 | } |
| 49 | |