net: fix lookupHost on Plan 9

CL 532217 added the newDNSError function.

However, the implementation was not correct on
Plan 9, which lead TestLookupNoSuchHost to fail.

This change fixes lookupHost on Plan 9.

Fixes #67096.

Change-Id: I39271f7d588b19c1b1608f18a24d871460be09cd
Reviewed-on: https://go-review.googlesource.com/c/go/+/582236
Reviewed-by: Joedian Reid <joedian@google.com>
Run-TryBot: David du Colombier <0intro@gmail.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>

diff --git a/src/net/lookup_plan9.go b/src/net/lookup_plan9.go
index 2532a0e967b25838ebcff5560fffb83bc43559f8..588174b1fc53ded73e43ab61ce643cb1cb8ee6c7 100644 (file)
--- a/src/net/lookup_plan9.go
+++ b/src/net/lookup_plan9.go
@@ -109,17 +109,11 @@ func queryDNS(ctx context.Context, addr string, typ string) (res []string, err e
 func handlePlan9DNSError(err error, name string) error {
        if stringsHasSuffix(err.Error(), "dns: name does not exist") ||
                stringsHasSuffix(err.Error(), "dns: resource does not exist; negrcode 0") ||
-               stringsHasSuffix(err.Error(), "dns: resource does not exist; negrcode") {
-               return &DNSError{
-                       Err:        errNoSuchHost.Error(),
-                       Name:       name,
-                       IsNotFound: true,
-               }
-       }
-       return &DNSError{
-               Err:  err.Error(),
-               Name: name,
+               stringsHasSuffix(err.Error(), "dns: resource does not exist; negrcode") ||
+               stringsHasSuffix(err.Error(), "dns failure") {
+               err = errNoSuchHost
        }
+       return newDNSError(err, name, "")
 }
 
 // toLower returns a lower-case version of in. Restricting us to
@@ -169,10 +163,7 @@ func (*Resolver) lookupHost(ctx context.Context, host string) (addrs []string, e
        // host names in local network (e.g. from /lib/ndb/local)
        lines, err := queryCS(ctx, "net", host, "1")
        if err != nil {
-               if stringsHasSuffix(err.Error(), "dns failure") {
-                       err = errNoSuchHost
-               }
-               return nil, newDNSError(err, host, "")
+               return nil, handlePlan9DNSError(err, host)
        }
 loop:
        for _, line := range lines {

diff --git a/src/net/lookup_test.go b/src/net/lookup_test.go
index bd58498fbc7224124761552c93b758baa2091060..97b37f2841aa2cd3e501f268c50dc4322dcfd886 100644 (file)
--- a/src/net/lookup_test.go
+++ b/src/net/lookup_test.go
@@ -1634,6 +1634,10 @@ func TestLookupNoSuchHost(t *testing.T) {
 }
 
 func TestDNSErrorUnwrap(t *testing.T) {
+       if runtime.GOOS == "plan9" {
+               // The Plan 9 implementation of the resolver doesn't use the Dial function yet. See https://go.dev/cl/409234
+               t.Skip("skipping on plan9")
+       }
        rDeadlineExcceeded := &Resolver{PreferGo: true, Dial: func(ctx context.Context, network, address string) (Conn, error) {
                return nil, context.DeadlineExceeded
        }}