net: make DNSError.Temporary return true on SERVFAIL
Fixes #8434
Change-Id: I323222b4160f3aba35cac1de7f6df93c524b72ec
Reviewed-on: https://go-review.googlesource.com/14169
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/net/dnsclient.go b/src/net/dnsclient.go
index ce48521..a2f5986 100644
--- a/src/net/dnsclient.go
+++ b/src/net/dnsclient.go
@@ -47,8 +47,13 @@
// None of the error codes make sense
// for the query we sent. If we didn't get
// a name error and we didn't get success,
- // the server is behaving incorrectly.
- return "", nil, &DNSError{Err: "server misbehaving", Name: name, Server: server}
+ // the server is behaving incorrectly or
+ // having temporary trouble.
+ err := &DNSError{Err: "server misbehaving", Name: name, Server: server}
+ if dns.rcode == dnsRcodeServerFailure {
+ err.IsTemporary = true
+ }
+ return "", nil, err
}
// Look for the name.
diff --git a/src/net/dnsclient_test.go b/src/net/dnsclient_test.go
index 3ab2b83..42b536c 100644
--- a/src/net/dnsclient_test.go
+++ b/src/net/dnsclient_test.go
@@ -67,3 +67,28 @@
func TestWeighting(t *testing.T) {
testWeighting(t, 0.05)
}
+
+// Issue 8434: verify that Temporary returns true on an error when rcode
+// is SERVFAIL
+func TestIssue8434(t *testing.T) {
+ msg := &dnsMsg{
+ dnsMsgHdr: dnsMsgHdr{
+ rcode: dnsRcodeServerFailure,
+ },
+ }
+
+ _, _, err := answer("golang.org", "foo:53", msg, uint16(dnsTypeSRV))
+ if err == nil {
+ t.Fatal("expected an error")
+ }
+ if ne, ok := err.(Error); !ok {
+ t.Fatalf("err = %#v; wanted something supporting net.Error", err)
+ } else if !ne.Temporary() {
+ t.Fatalf("Temporary = false for err = %#v; want Temporary == true", err)
+ }
+ if de, ok := err.(*DNSError); !ok {
+ t.Fatalf("err = %#v; wanted a *net.DNSError", err)
+ } else if !de.IsTemporary {
+ t.Fatalf("IsTemporary = false for err = %#v; want IsTemporary == true", err)
+ }
+}
diff --git a/src/net/net.go b/src/net/net.go
index 6e84c3a..4f1bf9d 100644
--- a/src/net/net.go
+++ b/src/net/net.go
@@ -520,10 +520,11 @@
// DNSError represents a DNS lookup error.
type DNSError struct {
- Err string // description of the error
- Name string // name looked for
- Server string // server used
- IsTimeout bool // if true, timed out; not all timeouts set this
+ Err string // description of the error
+ Name string // name looked for
+ Server string // server used
+ IsTimeout bool // if true, timed out; not all timeouts set this
+ IsTemporary bool // if true, error is temporary; not all errors set this
}
func (e *DNSError) Error() string {
@@ -546,7 +547,7 @@
// Temporary reports whether the DNS error is known to be temporary.
// This is not always known; a DNS lookup may fail due to a temporary
// error and return a DNSError for which Temporary returns false.
-func (e *DNSError) Temporary() bool { return e.IsTimeout }
+func (e *DNSError) Temporary() bool { return e.IsTimeout || e.IsTemporary }
type writerOnly struct {
io.Writer
