Function TestDNSTrampleRecovery

net/dns/direct_linux_test.go:21–76

(t *testing.T)

)

func TestDNSTrampleRecovery(t *testing.T) {
	t.Cleanup(HookWatchFile.SetForTest(watchFile))
	synctest.Test(t, func(t *testing.T) {
		tmp := t.TempDir()
		if err := os.MkdirAll(filepath.Join(tmp, "etc"), 0700); err != nil {
			t.Fatal(err)
		}
		const resolvPath = "/etc/resolv.conf"
		fs := directFS{prefix: tmp}
		readFile := func(t *testing.T, path string) string {
			t.Helper()
			b, err := fs.ReadFile(path)
			if err != nil {
				t.Errorf("Reading DNS config: %v", err)
			}
			return string(b)
		}

		bus := eventbustest.NewBus(t)
		eventbustest.LogAllEvents(t, bus)
		m := newDirectManagerOnFS(t.Logf, nil, bus, fs)
		defer m.Close()

		if err := m.SetDNS(OSConfig{
			Nameservers:   []netip.Addr{netip.MustParseAddr("8.8.8.8"), netip.MustParseAddr("8.8.4.4")},
			SearchDomains: []dnsname.FQDN{"ts.net.", "ts-dns.test."},
			MatchDomains:  []dnsname.FQDN{"ignored."},
		}); err != nil {
			t.Fatal(err)
		}

		const want = `# resolv.conf(5) file generated by tailscale
# For more info, see https://tailscale.com/s/resolvconf-overwrite
# DO NOT EDIT THIS FILE BY HAND -- CHANGES WILL BE OVERWRITTEN

nameserver 8.8.8.8
nameserver 8.8.4.4
search ts.net ts-dns.test
`
		if got := readFile(t, resolvPath); got != want {
			t.Fatalf("resolv.conf:\n%s, want:\n%s", got, want)
		}

		tw := eventbustest.NewWatcher(t, bus)

		const trample = "Hvem er det som tramper på min bro?"
		if err := fs.WriteFile(resolvPath, []byte(trample), 0644); err != nil {
			t.Fatal(err)
		}
		synctest.Wait()

		if err := eventbustest.Expect(tw, eventbustest.Type[TrampleDNS]()); err != nil {
			t.Errorf("did not see trample event: %s", err)
		}
	})
}

// watchFile is a test implementation of the file watcher that uses a timer