char: don't skip client cleanup if 'connected' flag is unset

The tcp_chr_free_connection & tcp_chr_disconnect methods both
skip all of their cleanup work unless the 's->connected' flag
is set.  This flag is set when the incoming client connection
is ready to use. Crucially this is *after* the TLS handshake
has been completed. So if the TLS handshake fails and we try
to cleanup the failed client, all the cleanup is skipped as
's->connected' is still false.

The only important thing that should be skipped in this case
is sending of the CHR_EVENT_CLOSED, because we never got as
far as sending the corresponding CHR_EVENT_OPENED. Every other
bit of cleanup can be robust against being called even when
s->connected is false.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <20171005155057.7664-1-berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

chardev/char-socket.c

@@ -332,10 +332,6 @@ static void tcp_chr_free_connection(Chardev *chr)
     SocketChardev *s = SOCKET_CHARDEV(chr);
     int i;
 
-    if (!s->connected) {
-        return;
-    }
-
     if (s->read_msgfds_num) {
         for (i = 0; i < s->read_msgfds_num; i++) {
             close(s->read_msgfds[i]);
@@ -394,22 +390,25 @@ static void update_disconnected_filename(SocketChardev *s)
                                          s->is_listen, s->is_telnet);
 }
 
+/* NB may be called even if tcp_chr_connect has not been
+ * reached, due to TLS or telnet initialization failure,
+ * so can *not* assume s->connected == true
+ */
 static void tcp_chr_disconnect(Chardev *chr)
 {
     SocketChardev *s = SOCKET_CHARDEV(chr);
-
-    if (!s->connected) {
-        return;
-    }
+    bool emit_close = s->connected;
 
     tcp_chr_free_connection(chr);
 
-    if (s->listen_ioc) {
+    if (s->listen_ioc && s->listen_tag == 0) {
         s->listen_tag = qio_channel_add_watch(
             QIO_CHANNEL(s->listen_ioc), G_IO_IN, tcp_chr_accept, chr, NULL);
     }
     update_disconnected_filename(s);
-    qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
+    if (emit_close) {
+        qemu_chr_be_event(chr, CHR_EVENT_CLOSED);
+    }
     if (s->reconnect_time) {
         qemu_chr_socket_restart_timer(chr);
     }