unix-fd: when sending a message with unix fds verify that the connection can do it

Not all of the send function flavours allow returning proper error
codes. For the cases where this is not easily possible the client should
call dbus_connection_can_send_type() first.

1 files changed, 69 insertions, 7 deletions

diff --git a/dbus/dbus-connection.c b/dbus/dbus-connection.c
index fc872bc2..8433b643 100644
--- a/dbus/dbus-connection.c
+++ b/dbus/dbus-connection.c
@@ -3086,8 +3086,23 @@ dbus_connection_send_preallocated (DBusConnection       *connection,
   _dbus_return_if_fail (dbus_message_get_type (message) != DBUS_MESSAGE_TYPE_SIGNAL ||
                         (dbus_message_get_interface (message) != NULL &&
                          dbus_message_get_member (message) != NULL));
-  
+
   CONNECTION_LOCK (connection);
+
+#ifdef HAVE_UNIX_FD_PASSING
+
+  if (!_dbus_transport_can_pass_unix_fd(connection->transport) &&
+      message->n_unix_fds > 0)
+    {
+      /* Refuse to send fds on a connection that cannot handle
+         them. Unfortunately we cannot return a proper error here, so
+         the best we can is just return. */
+      CONNECTION_UNLOCK (connection);
+      return;
+    }
+
+#endif
+
   _dbus_connection_send_preallocated_and_unlock (connection,
 						 preallocated,
 						 message, client_serial);
@@ -3151,6 +3166,20 @@ dbus_connection_send (DBusConnection *connection,
 
   CONNECTION_LOCK (connection);
 
+#ifdef HAVE_UNIX_FD_PASSING
+
+  if (!_dbus_transport_can_pass_unix_fd(connection->transport) &&
+      message->n_unix_fds > 0)
+    {
+      /* Refuse to send fds on a connection that cannot handle
+         them. Unfortunately we cannot return a proper error here, so
+         the best we can is just return. */
+      CONNECTION_UNLOCK (connection);
+      return FALSE;
+    }
+
+#endif
+
   return _dbus_connection_send_and_unlock (connection,
 					   message,
 					   serial);
@@ -3207,12 +3236,16 @@ reply_handler_timeout (void *data)
  * timeout to mean "very long timeout." libdbus clamps an INT_MAX
  * timeout down to a few hours timeout though.
  *
- * @warning if the connection is disconnected, the #DBusPendingCall
- * will be set to #NULL, so be careful with this.
- * 
+ * @warning if the connection is disconnected or you try to send Unix
+ * file descriptors on a connection that does not support them, the
+ * #DBusPendingCall will be set to #NULL, so be careful with this.
+ *
  * @param connection the connection
  * @param message the message to send
- * @param pending_return return location for a #DBusPendingCall object, or #NULL if connection is disconnected
+ * @param pending_return return location for a #DBusPendingCall
+ * object, or #NULL if connection is disconnected or when you try to
+ * send Unix file descriptors on a connection that does not support
+ * them.
  * @param timeout_milliseconds timeout in milliseconds or -1 for default
  * @returns #FALSE if no memory, #TRUE otherwise.
  *
@@ -3236,6 +3269,21 @@ dbus_connection_send_with_reply (DBusConnection     *connection,
 
   CONNECTION_LOCK (connection);
 
+#ifdef HAVE_UNIX_FD_PASSING
+
+  if (!_dbus_transport_can_pass_unix_fd(connection->transport) &&
+      message->n_unix_fds > 0)
+    {
+      /* Refuse to send fds on a connection that cannot handle
+         them. Unfortunately we cannot return a proper error here, so
+         the best we can do is return TRUE but leave *pending_return
+         as NULL. */
+      CONNECTION_UNLOCK (connection);
+      return TRUE;
+    }
+
+#endif
+
    if (!_dbus_connection_get_is_connected_unlocked (connection))
     {
       CONNECTION_UNLOCK (connection);
@@ -3344,12 +3392,26 @@ dbus_connection_send_with_reply_and_block (DBusConnection     *connection,
 {
   DBusMessage *reply;
   DBusPendingCall *pending;
-  
+
   _dbus_return_val_if_fail (connection != NULL, NULL);
   _dbus_return_val_if_fail (message != NULL, NULL);
   _dbus_return_val_if_fail (timeout_milliseconds >= 0 || timeout_milliseconds == -1, NULL);
   _dbus_return_val_if_error_is_set (error, NULL);
-  
+
+#ifdef HAVE_UNIX_FD_PASSING
+
+  CONNECTION_LOCK (connection);
+  if (!_dbus_transport_can_pass_unix_fd(connection->transport) &&
+      message->n_unix_fds > 0)
+    {
+      CONNECTION_UNLOCK (connection);
+      dbus_set_error(error, DBUS_ERROR_FAILED, "Cannot send file descriptors on this connection.");
+      return NULL;
+    }
+  CONNECTION_UNLOCK (connection);
+
+#endif
+
   if (!dbus_connection_send_with_reply (connection, message,
                                         &pending, timeout_milliseconds))
     {