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net: avoid race on test hooks with DNS goroutines

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The DNS code can start goroutines and not wait for them to complete.
This does no harm, but in tests this can cause a race condition with
the test hooks that are installed and unintalled around the tests.
Add a WaitGroup that tests of DNS can use to avoid the race.

Fixes #21090

Change-Id: I6c1443a9c2378e8b89d0ab1d6390c0e3e726b0ce
Reviewed-on: https://go-review.googlesource.com/82795
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Ian Lance Taylor 2017-12-07 20:30:28 -08:00
parent 6af8c0d812
commit 6c877e5da7
7 changed files with 95 additions and 5 deletions
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41
src/net/dnsclient_unix_test.go
View file

@ -203,6 +203,7 @@ var fakeDNSServerSuccessful = fakeDNSServer{func(_, _ string, q *dnsMsg, _ time.
// Issue 13705: don't try to resolve onion addresses, etc
func TestLookupTorOnion(t *testing.T) {
defer dnsWaitGroup.Wait()
r := Resolver{PreferGo: true, Dial: fakeDNSServerSuccessful.DialContext}
addrs, err := r.LookupIPAddr(context.Background(), "foo.onion")
if err != nil {
@ -300,6 +301,8 @@ var updateResolvConfTests = []struct {
}
func TestUpdateResolvConf(t *testing.T) {
defer dnsWaitGroup.Wait()
r := Resolver{PreferGo: true, Dial: fakeDNSServerSuccessful.DialContext}
conf, err := newResolvConfTest()
@ -455,6 +458,8 @@ var goLookupIPWithResolverConfigTests = []struct {
}
func TestGoLookupIPWithResolverConfig(t *testing.T) {
defer dnsWaitGroup.Wait()
fake := fakeDNSServer{func(n, s string, q *dnsMsg, _ time.Time) (*dnsMsg, error) {
switch s {
case "[2001:4860:4860::8888]:53", "8.8.8.8:53":
@ -547,6 +552,8 @@ func TestGoLookupIPWithResolverConfig(t *testing.T) {
// Test that goLookupIPOrder falls back to the host file when no DNS servers are available.
func TestGoLookupIPOrderFallbackToFile(t *testing.T) {
defer dnsWaitGroup.Wait()
fake := fakeDNSServer{func(n, s string, q *dnsMsg, tm time.Time) (*dnsMsg, error) {
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
@ -603,6 +610,8 @@ func TestGoLookupIPOrderFallbackToFile(t *testing.T) {
// querying the original name instead of an error encountered
// querying a generated name.
func TestErrorForOriginalNameWhenSearching(t *testing.T) {
defer dnsWaitGroup.Wait()
const fqdn = "doesnotexist.domain"
conf, err := newResolvConfTest()
@ -657,6 +666,8 @@ func TestErrorForOriginalNameWhenSearching(t *testing.T) {
// Issue 15434. If a name server gives a lame referral, continue to the next.
func TestIgnoreLameReferrals(t *testing.T) {
defer dnsWaitGroup.Wait()
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
@ -889,6 +900,8 @@ func TestIgnoreDNSForgeries(t *testing.T) {
// Issue 16865. If a name server times out, continue to the next.
func TestRetryTimeout(t *testing.T) {
defer dnsWaitGroup.Wait()
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
@ -945,6 +958,8 @@ func TestRotate(t *testing.T) {
}
func testRotate(t *testing.T, rotate bool, nameservers, wantServers []string) {
defer dnsWaitGroup.Wait()
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
@ -1008,6 +1023,8 @@ func mockTXTResponse(q *dnsMsg) *dnsMsg {
// Issue 17448. With StrictErrors enabled, temporary errors should make
// LookupIP fail rather than return a partial result.
func TestStrictErrorsLookupIP(t *testing.T) {
defer dnsWaitGroup.Wait()
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
@ -1256,6 +1273,8 @@ func TestStrictErrorsLookupIP(t *testing.T) {
// Issue 17448. With StrictErrors enabled, temporary errors should make
// LookupTXT stop walking the search list.
func TestStrictErrorsLookupTXT(t *testing.T) {
defer dnsWaitGroup.Wait()
conf, err := newResolvConfTest()
if err != nil {
t.Fatal(err)
@ -1312,3 +1331,25 @@ func TestStrictErrorsLookupTXT(t *testing.T) {
}
}
}
// Test for a race between uninstalling the test hooks and closing a
// socket connection. This used to fail when testing with -race.
func TestDNSGoroutineRace(t *testing.T) {
defer dnsWaitGroup.Wait()
fake := fakeDNSServer{func(n, s string, q *dnsMsg, t time.Time) (*dnsMsg, error) {
time.Sleep(10 * time.Microsecond)
return nil, poll.ErrTimeout
}}
r := Resolver{PreferGo: true, Dial: fake.DialContext}
// The timeout here is less than the timeout used by the server,
// so the goroutine started to query the (fake) server will hang
// around after this test is done if we don't call dnsWaitGroup.Wait.
ctx, cancel := context.WithTimeout(context.Background(), 2*time.Microsecond)
defer cancel()
_, err := r.LookupIPAddr(ctx, "where.are.they.now")
if err == nil {
t.Fatal("fake DNS lookup unexpectedly succeeded")
}
}