components/golang-17/patches/0009-release-branch.go1.7-net-restore-per-query-timeout-l.patch
PSARC/2016/250 Google Go version 1.7
23170486 update to Google Go version 1.7 and add sparc64 support
From bb8706890bc5bab01894f7faf382b15364635d29 Mon Sep 17 00:00:00 2001
From: Matthew Dempsky <[email protected]>
Date: Mon, 29 Aug 2016 13:53:32 -0700
Subject: [PATCH 09/38] [release-branch.go1.7] net: restore per-query timeout
logic
The handling of "options timeout:n" is supposed to be per individual
DNS server exchange, not per Lookup call.
Fixes #16865.
Change-Id: I2304579b9169c1515292f142cb372af9d37ff7c1
Reviewed-on: https://go-review.googlesource.com/28057
Run-TryBot: Matthew Dempsky <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Brad Fitzpatrick <[email protected]>
Reviewed-on: https://go-review.googlesource.com/28640
---
src/net/dnsclient_unix.go | 17 ++++----
src/net/dnsclient_unix_test.go | 96 ++++++++++++++++++++++++++++++++++++------
2 files changed, 92 insertions(+), 21 deletions(-)
diff --git a/src/net/dnsclient_unix.go b/src/net/dnsclient_unix.go
index d12944c..b5b6ffb 100644
--- a/src/net/dnsclient_unix.go
+++ b/src/net/dnsclient_unix.go
@@ -141,7 +141,7 @@ func (d *Dialer) dialDNS(ctx context.Context, network, server string) (dnsConn,
}
// exchange sends a query on the connection and hopes for a response.
-func exchange(ctx context.Context, server, name string, qtype uint16) (*dnsMsg, error) {
+func exchange(ctx context.Context, server, name string, qtype uint16, timeout time.Duration) (*dnsMsg, error) {
d := testHookDNSDialer()
out := dnsMsg{
dnsMsgHdr: dnsMsgHdr{
@@ -152,6 +152,12 @@ func exchange(ctx context.Context, server, name string, qtype uint16) (*dnsMsg,
},
}
for _, network := range []string{"udp", "tcp"} {
+ // TODO(mdempsky): Refactor so defers from UDP-based
+ // exchanges happen before TCP-based exchange.
+
+ ctx, cancel := context.WithDeadline(ctx, time.Now().Add(timeout))
+ defer cancel()
+
c, err := d.dialDNS(ctx, network, server)
if err != nil {
return nil, err
@@ -180,17 +186,10 @@ func tryOneName(ctx context.Context, cfg *dnsConfig, name string, qtype uint16)
return "", nil, &DNSError{Err: "no DNS servers", Name: name}
}
- deadline := time.Now().Add(cfg.timeout)
- if old, ok := ctx.Deadline(); !ok || deadline.Before(old) {
- var cancel context.CancelFunc
- ctx, cancel = context.WithDeadline(ctx, deadline)
- defer cancel()
- }
-
var lastErr error
for i := 0; i < cfg.attempts; i++ {
for _, server := range cfg.servers {
- msg, err := exchange(ctx, server, name, qtype)
+ msg, err := exchange(ctx, server, name, qtype, cfg.timeout)
if err != nil {
lastErr = &DNSError{
Err: err.Error(),
diff --git a/src/net/dnsclient_unix_test.go b/src/net/dnsclient_unix_test.go
index c953c1e..6ebeeae 100644
--- a/src/net/dnsclient_unix_test.go
+++ b/src/net/dnsclient_unix_test.go
@@ -40,9 +40,9 @@ func TestDNSTransportFallback(t *testing.T) {
testenv.MustHaveExternalNetwork(t)
for _, tt := range dnsTransportFallbackTests {
- ctx, cancel := context.WithTimeout(context.Background(), time.Duration(tt.timeout)*time.Second)
+ ctx, cancel := context.WithCancel(context.Background())
defer cancel()
- msg, err := exchange(ctx, tt.server, tt.name, tt.qtype)
+ msg, err := exchange(ctx, tt.server, tt.name, tt.qtype, time.Second)
if err != nil {
t.Error(err)
continue
@@ -82,9 +82,9 @@ func TestSpecialDomainName(t *testing.T) {
server := "8.8.8.8:53"
for _, tt := range specialDomainNameTests {
- ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+ ctx, cancel := context.WithCancel(context.Background())
defer cancel()
- msg, err := exchange(ctx, server, tt.name, tt.qtype)
+ msg, err := exchange(ctx, server, tt.name, tt.qtype, 3*time.Second)
if err != nil {
t.Error(err)
continue
@@ -501,7 +501,7 @@ func TestErrorForOriginalNameWhenSearching(t *testing.T) {
d := &fakeDNSDialer{}
testHookDNSDialer = func() dnsDialer { return d }
- d.rh = func(s string, q *dnsMsg) (*dnsMsg, error) {
+ d.rh = func(s string, q *dnsMsg, _ time.Time) (*dnsMsg, error) {
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
id: q.id,
@@ -540,14 +540,15 @@ func TestIgnoreLameReferrals(t *testing.T) {
}
defer conf.teardown()
- if err := conf.writeAndUpdate([]string{"nameserver 192.0.2.1", "nameserver 192.0.2.2"}); err != nil {
+ if err := conf.writeAndUpdate([]string{"nameserver 192.0.2.1", // the one that will give a lame referral
+ "nameserver 192.0.2.2"}); err != nil {
t.Fatal(err)
}
d := &fakeDNSDialer{}
testHookDNSDialer = func() dnsDialer { return d }
- d.rh = func(s string, q *dnsMsg) (*dnsMsg, error) {
+ d.rh = func(s string, q *dnsMsg, _ time.Time) (*dnsMsg, error) {
t.Log(s, q)
r := &dnsMsg{
dnsMsgHdr: dnsMsgHdr{
@@ -634,28 +635,30 @@ func BenchmarkGoLookupIPWithBrokenNameServer(b *testing.B) {
type fakeDNSDialer struct {
// reply handler
- rh func(s string, q *dnsMsg) (*dnsMsg, error)
+ rh func(s string, q *dnsMsg, t time.Time) (*dnsMsg, error)
}
func (f *fakeDNSDialer) dialDNS(_ context.Context, n, s string) (dnsConn, error) {
- return &fakeDNSConn{f.rh, s}, nil
+ return &fakeDNSConn{f.rh, s, time.Time{}}, nil
}
type fakeDNSConn struct {
- rh func(s string, q *dnsMsg) (*dnsMsg, error)
+ rh func(s string, q *dnsMsg, t time.Time) (*dnsMsg, error)
s string
+ t time.Time
}
func (f *fakeDNSConn) Close() error {
return nil
}
-func (f *fakeDNSConn) SetDeadline(time.Time) error {
+func (f *fakeDNSConn) SetDeadline(t time.Time) error {
+ f.t = t
return nil
}
func (f *fakeDNSConn) dnsRoundTrip(q *dnsMsg) (*dnsMsg, error) {
- return f.rh(f.s, q)
+ return f.rh(f.s, q, f.t)
}
// UDP round-tripper algorithm should ignore invalid DNS responses (issue 13281).
@@ -725,3 +728,72 @@ func TestIgnoreDNSForgeries(t *testing.T) {
t.Errorf("got address %v, want %v", got, TestAddr)
}
}
+
+// Issue 16865. If a name server times out, continue to the next.
+func TestRetryTimeout(t *testing.T) {
+ origTestHookDNSDialer := testHookDNSDialer
+ defer func() { testHookDNSDialer = origTestHookDNSDialer }()
+
+ conf, err := newResolvConfTest()
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer conf.teardown()
+
+ if err := conf.writeAndUpdate([]string{"nameserver 192.0.2.1", // the one that will timeout
+ "nameserver 192.0.2.2"}); err != nil {
+ t.Fatal(err)
+ }
+
+ d := &fakeDNSDialer{}
+ testHookDNSDialer = func() dnsDialer { return d }
+
+ var deadline0 time.Time
+
+ d.rh = func(s string, q *dnsMsg, deadline time.Time) (*dnsMsg, error) {
+ t.Log(s, q, deadline)
+
+ if deadline.IsZero() {
+ t.Error("zero deadline")
+ }
+
+ if s == "192.0.2.1:53" {
+ deadline0 = deadline
+ time.Sleep(10 * time.Millisecond)
+ return nil, errTimeout
+ }
+
+ if deadline == deadline0 {
+ t.Error("deadline didn't change")
+ }
+
+ r := &dnsMsg{
+ dnsMsgHdr: dnsMsgHdr{
+ id: q.id,
+ response: true,
+ recursion_available: true,
+ },
+ question: q.question,
+ answer: []dnsRR{
+ &dnsRR_CNAME{
+ Hdr: dnsRR_Header{
+ Name: q.question[0].Name,
+ Rrtype: dnsTypeCNAME,
+ Class: dnsClassINET,
+ },
+ Cname: "golang.org",
+ },
+ },
+ }
+ return r, nil
+ }
+
+ _, err = goLookupCNAME(context.Background(), "www.golang.org")
+ if err != nil {
+ t.Fatal(err)
+ }
+
+ if deadline0.IsZero() {
+ t.Error("deadline0 still zero", deadline0)
+ }
+}
--
2.7.4