net: Resolver.LookupIP return error for empty string

Fixes #53995 Change-Id: Ib0de237b57382feb6b8070f2310945aef6c7db01 Reviewed-on: https://go-review.googlesource.com/c/go/+/419734 Reviewed-by: Damien Neil <[email protected]> Reviewed-by: David Chase <[email protected]> TryBot-Result: Gopher Robot <[email protected]> Run-TryBot: Damien Neil <[email protected]>
golang · Aug 26, 2022 · 333681d · 333681d
1 parent acabf87
commit 333681d
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diff --git a/src/net/lookup.go b/src/net/lookup.go
@@ -224,10 +224,15 @@ func (r *Resolver) LookupIP(ctx context.Context, network, host string) ([]IP, er
 	default:
 		return nil, UnknownNetworkError(network)
 	}
+
+	if host == "" {
+		return nil, &DNSError{Err: errNoSuchHost.Error(), Name: host, IsNotFound: true}
+	}
 	addrs, err := r.internetAddrList(ctx, afnet, host)
 	if err != nil {
 		return nil, err
 	}
+
 	ips := make([]IP, 0, len(addrs))
 	for _, addr := range addrs {
 		ips = append(ips, addr.(*IPAddr).IP)

diff --git a/src/net/lookup_test.go b/src/net/lookup_test.go
@@ -1208,6 +1208,17 @@ func TestLookupIPAddrConcurrentCallsForNetworks(t *testing.T) {
 	wg.Wait()
 }
 
+// Issue 53995: Resolver.LookupIP should return error for empty host name.
+func TestResolverLookupIPWithEmptyHost(t *testing.T) {
+	_, err := DefaultResolver.LookupIP(context.Background(), "ip", "")
+	if err == nil {
+		t.Fatal("DefaultResolver.LookupIP for empty host success, want no host error")
+	}
+	if !strings.HasSuffix(err.Error(), errNoSuchHost.Error()) {
+		t.Fatalf("lookup error = %v, want %v", err, errNoSuchHost)
+	}
+}
+
 func TestWithUnexpiredValuesPreserved(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())