syscall: fix nacl listener to not accept connections once closed

Change-Id: I3ba6e97089ef6e69ba31dfb632df465859906a74
Reviewed-on: https://go-review.googlesource.com/15940
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/net/net_test.go

@@ -208,7 +208,6 @@ func TestListenerClose(t *testing.T) {
 		case "unix", "unixpacket":
 			defer os.Remove(ln.Addr().String())
 		}
-		defer ln.Close()
 
 		if err := ln.Close(); err != nil {
 			if perr := parseCloseError(err); perr != nil {
@@ -221,6 +220,14 @@ func TestListenerClose(t *testing.T) {
 			c.Close()
 			t.Fatal("should fail")
 		}
+
+		if network == "tcp" {
+			cc, err := Dial("tcp", ln.Addr().String())
+			if err == nil {
+				t.Error("Dial to closed TCP listener succeeeded.")
+				cc.Close()
+			}
+		}
 	}
 }
 

src/syscall/net_nacl.go

@@ -577,7 +577,7 @@ func (f *netFile) connect(sa Sockaddr) error {
 		return EISCONN
 	}
 	l, ok := net.listener[netAddr{f.proto, f.sotype, sa.key()}]
-	if !ok {
+	if !ok || l.listenerClosed() {
 		net.Unlock()
 		return ECONNREFUSED
 	}
@@ -676,6 +676,12 @@ func (f *netFile) sendto(p []byte, flags int, to Sockaddr) error {
 	return nil
 }
 
+func (f *netFile) listenerClosed() bool {
+	f.listener.Lock()
+	defer f.listener.Unlock()
+	return f.listener.closed
+}
+
 func (f *netFile) close() error {
 	if f.listener != nil {
 		f.listener.close()