[GUACAMOLE-1918] Multitouch attribute not correctly synced for guac_common_surface

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.5.5
• Component/s: guacamole-server
• Assignee: Mike Jumper
• Reporter: Mike Jumper
• Created: 02/Feb/24 17:03
• Updated: 02/Feb/24 17:23
• Resolved: 02/Feb/24 17:23

Description

The guac_common_surface_dup() function currently contains the following code for syncing the multitouch support attribute for a layer:

    /* Synchronize layer-specific properties if applicable */
    if (surface->layer->index > 0) {

        /* Synchronize opacity */
        guac_protocol_send_shade(socket, surface->layer, surface->opacity);

        /* Synchronize location and hierarchy */
        guac_protocol_send_move(socket, surface->layer,
                surface->parent, surface->x, surface->y, surface->z);

        /* Synchronize multi-touch support level */
        guac_protocol_send_set_int(surface->socket, surface->layer,
                GUAC_PROTOCOL_LAYER_PARAMETER_MULTI_TOUCH,
                surface->touches);

    }

This is incorrect because:

• The multitouch attribute applies only to the default layer (layer 0), but this if ensures that's exactly the only layer this function won't send that attribute for.
• The wrong guac_socket is referenced (it should be sent to the socket supplied to the guac_common_surface_dup() call, not the surface's socket.

Depending on timing of any call to guac_common_surface_set_multitouch(), this can result in multitouch support not having any effect.

Instead, the multitouch attribute should be sent for only the default layer and to the correct socket.