net: treat EAI_NODATA as errNoSuchHost

man getaddrinfo:
EAI_NODATA
              The specified network host exists, but does not have any
              network addresses defined.

In the go resolver we treat this kind of error as nosuchhost.

Change-Id: I69fab6f8da8e3a86907e65104bca9f055968633a
GitHub-Last-Rev: b4891e2addaeccecb242d0485daa168bb55cf54e
GitHub-Pull-Request: golang/go#57507
Reviewed-on: https://go-review.googlesource.com/c/go/+/459955
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Mateusz Poliwczak <mpoliwczak34@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

diff --git a/src/internal/syscall/unix/net_darwin.go b/src/internal/syscall/unix/net_darwin.go
index b9da4f1dc75bfdf3de93c4d57be68b26c33e8cd3..8b908ae600625966a9724b3dc5c3c32810b16a32 100644 (file)
--- a/src/internal/syscall/unix/net_darwin.go
+++ b/src/internal/syscall/unix/net_darwin.go
@@ -17,6 +17,7 @@ const (
        AI_MASK      = 0x1407
 
        EAI_AGAIN    = 2
+       EAI_NODATA   = 7
        EAI_NONAME   = 8
        EAI_SYSTEM   = 11
        EAI_OVERFLOW = 14

diff --git a/src/net/cgo_unix.go b/src/net/cgo_unix.go
index e378a87ba30be8c81634013072f3178c2332dbcc..c5281ad3a5a2fef8c88507771e4d90c2d62a5559 100644 (file)
--- a/src/net/cgo_unix.go
+++ b/src/net/cgo_unix.go
@@ -166,7 +166,7 @@ func cgoLookupHostIP(network, name string) (addrs []IPAddr, err error) {
                                // comes up again. golang.org/issue/6232.
                                err = syscall.EMFILE
                        }
-               case _C_EAI_NONAME:
+               case _C_EAI_NONAME, _C_EAI_NODATA:
                        err = errNoSuchHost
                        isErrorNoSuchHost = true
                default:

diff --git a/src/net/cgo_unix_cgo.go b/src/net/cgo_unix_cgo.go
index 69876a675ae6d30d9c1035040af26471f89f63cc..c0aa373a9b98527388d1f98d9059cfbe5a7d54ff 100644 (file)
--- a/src/net/cgo_unix_cgo.go
+++ b/src/net/cgo_unix_cgo.go
@@ -7,6 +7,8 @@
 package net
 
 /*
+#define _GNU_SOURCE
+
 #cgo CFLAGS: -fno-stack-protector
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -16,6 +18,10 @@ package net
 #include <string.h>
 #include <stdlib.h>
 
+#ifndef EAI_NODATA
+#define EAI_NODATA -5
+#endif
+
 // If nothing else defined EAI_OVERFLOW, make sure it has a value.
 #ifndef EAI_OVERFLOW
 #define EAI_OVERFLOW -12
@@ -29,6 +35,7 @@ const (
        _C_AF_INET6     = C.AF_INET6
        _C_AF_UNSPEC    = C.AF_UNSPEC
        _C_EAI_AGAIN    = C.EAI_AGAIN
+       _C_EAI_NODATA   = C.EAI_NODATA
        _C_EAI_NONAME   = C.EAI_NONAME
        _C_EAI_OVERFLOW = C.EAI_OVERFLOW
        _C_EAI_SYSTEM   = C.EAI_SYSTEM

diff --git a/src/net/cgo_unix_syscall.go b/src/net/cgo_unix_syscall.go
index 0f643a021d1f4f913e50b907deade817a6ac66a8..cbdeb4771447d3a0839fedd3a941884043a59f59 100644 (file)
--- a/src/net/cgo_unix_syscall.go
+++ b/src/net/cgo_unix_syscall.go
@@ -19,6 +19,7 @@ const (
        _C_AF_UNSPEC    = syscall.AF_UNSPEC
        _C_EAI_AGAIN    = unix.EAI_AGAIN
        _C_EAI_NONAME   = unix.EAI_NONAME
+       _C_EAI_NODATA   = unix.EAI_NODATA
        _C_EAI_OVERFLOW = unix.EAI_OVERFLOW
        _C_EAI_SYSTEM   = unix.EAI_SYSTEM
        _C_IPPROTO_TCP  = syscall.IPPROTO_TCP

diff --git a/src/net/lookup_test.go b/src/net/lookup_test.go
index dfcf62b1c49d73a4be52c102f1eb5fe1a09e678f..b47e444375fcb468bcc6c68ec19f41cf731fa55f 100644 (file)
--- a/src/net/lookup_test.go
+++ b/src/net/lookup_test.go
@@ -8,6 +8,7 @@ package net
 
 import (
        "context"
+       "errors"
        "fmt"
        "internal/testenv"
        "net/netip"
@@ -1398,3 +1399,66 @@ func TestDNSTimeout(t *testing.T) {
        checkErr(err2)
        cancel()
 }
+
+func TestLookupNoData(t *testing.T) {
+       if runtime.GOOS == "plan9" {
+               t.Skip("not supported on plan9")
+       }
+
+       mustHaveExternalNetwork(t)
+
+       testLookupNoData(t, "default resolver")
+
+       func() {
+               defer forceGoDNS()()
+               testLookupNoData(t, "forced go resolver")
+       }()
+
+       func() {
+               defer forceCgoDNS()()
+               testLookupNoData(t, "forced cgo resolver")
+       }()
+}
+
+func testLookupNoData(t *testing.T, prefix string) {
+       attempts := 0
+       for {
+               // Domain that doesn't have any A/AAAA RRs, but has different one (in this case a TXT),
+               // so that it returns an empty response without any error codes (NXDOMAIN).
+               _, err := LookupHost("golang.rsc.io")
+               if err == nil {
+                       t.Errorf("%v: unexpected success", prefix)
+                       return
+               }
+
+               var dnsErr *DNSError
+               if errors.As(err, &dnsErr) {
+                       succeeded := true
+                       if !dnsErr.IsNotFound {
+                               succeeded = false
+                               t.Logf("%v: IsNotFound is set to false", prefix)
+                       }
+
+                       if dnsErr.Err != errNoSuchHost.Error() {
+                               succeeded = false
+                               t.Logf("%v: error message is not equal to: %v", prefix, errNoSuchHost.Error())
+                       }
+
+                       if succeeded {
+                               return
+                       }
+               }
+
+               testenv.SkipFlakyNet(t)
+               if attempts < len(backoffDuration) {
+                       dur := backoffDuration[attempts]
+                       t.Logf("%v: backoff %v after failure %v\n", prefix, dur, err)
+                       time.Sleep(dur)
+                       attempts++
+                       continue
+               }
+
+               t.Errorf("%v: unexpected error: %v", prefix, err)
+               return
+       }
+}