11.5. How to plugin related interface options
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## 11.5. How to plugin related interface options

To demonstrate the functionality of the plugin interface options, a demonstration plugin exists named "pluginifdemo". To build it using CMake, the build option `ENABLE_PLUGIN_IFDEMO` has to be enabled.

### 11.5.1. Implement a plugin GUI menu

Plugins (as well as built-in dissectors) may implement menus within Wireshark which can be used to trigger options, start tools, open Websites, and other actions.

This menu structure is built using the plugin_if.h interface and its corresponding functions.

The menu items all call a callback provided by the plugin, which takes a pointer to the menuitem entry as data. This pointer may be used to provide userdata to each entry. The pointer must utilize WS_DLL_PUBLIC_DEF and has the following structure:

    WS_DLL_PUBLIC_DEF void
    menu_cb(ext_menubar_gui_type gui_type, void *gui_data,
            void *user_data _U_)
    {
        ... Do something ...
    }

The menu entries themselves are generated with the following code structure:

    ext_menu_t * ext_menu, *os_menu = NULL;

    ext_menu = ext_menubar_register_menu (
            <your_proto_item>, "Some Menu Entry", true );
    ext_menubar_add_entry(ext_menu, "Test Entry 1",
            "This is a tooltip", menu_cb, <user_data>);
    ext_menubar_add_entry(ext_menu, "Test Entry 2",
            NULL, menu_cb, <user_data>);

    os_menu = ext_menubar_add_submenu(ext_menu, "Sub Menu" );
    ext_menubar_add_entry(os_menu, "Test Entry A",
            NULL, menu_cb, <user_data>);
    ext_menubar_add_entry(os_menu, "Test Entry B",
            NULL, menu_cb, <user_data>);

For a more detailed information, please refer to plugin_if.h.

### 11.5.2. Implement interactions with the main interface

Due to memory constraints on most platforms, plugin functionality cannot be called directly from a DLL context. Instead special functions will be used, which will implement certain options for plugins to utilize.

The following methods exist so far:

    /* Applies the given filter string as display filter */
    WS_DLL_PUBLIC void plugin_if_apply_filter
            (const char * filter_string, bool force);

    /* Saves the given preference to the main preference storage */
    WS_DLL_PUBLIC void plugin_if_save_preference
            (const char * pref_module, const char * pref_key, const char * pref_value);

    /* Jumps to the given frame number */
    WS_DLL_PUBLIC void plugin_if_goto_frame(uint32_t framenr);

### 11.5.3. Implement a plugin specific toolbar

A toolbar may be registered which allows implementing an interactive user interaction with the main application. The toolbar is generated using the following code:

    ext_toolbar_t * tb = ext_toolbar_register_toolbar("Plugin Interface Demo Toolbar");

This registers a toolbar, which will be shown underneath "View→Additional Toolbars" in the main menu, as well as the popup action window when right-clicking on any other tool- or menubar.

It behaves identically to the existing toolbars and can be hidden as well as defined to appear specific to selected profiles. The name with which it is being shown is the given name in this function call.

#### 11.5.3.1. Register elements for the toolbar

To add items to the toolbar, 4 different types of elements do exist.

- BOOLEAN - a checkbox to select / unselect
- BUTTON - a button to click
- STRING - a text field with validation options
- SELECTOR - a dropdown selection field

To add an element to the toolbar, the following function can be used:

    ext_toolbar_add_entry( ext_toolbar_t * parent, ext_toolbar_item_t type, const char *label,
        const char *defvalue, const char *tooltip, bool capture_only, GList * value_list,
        bool is_required, const char * regex, ext_toolbar_action_cb callback, void *user_data)

    parent_bar - the parent toolbar for this entry, to be registered by ext_toolbar_register_toolbar
    name - the entry name (the internal used one) for the item, used to send updates to the element
    label - the entry label (the displayed name) for the item, visible to the user
    defvalue - the default value for the toolbar element
        - EXT_TOOLBAR_BOOLEAN - 1 is for a checked element, 0 is unchecked
        - EXT_TOOLBAR_STRING - Text already entered upon initial display
    tooltip - a tooltip to be displayed on mouse-over
    capture_only - entry is only active, if a capture is active
    callback - the action which will be invoked after the item is activated
    value_list - a non-null list of values created by ext_toolbar_add_val(), if the item type
        is EXT_TOOLBAR_SELECTOR
    valid_regex - a validation regular expression for EXT_TOOLBAR_STRING
    is_required - a zero entry for EXT_TOOLBAR_STRING is not allowed
    user_data - a user defined pointer, which will be added to the toolbar callback

In case of the toolbar type EXT_TOOLBAR_SELECTOR a value list has to be provided. This list is generated using ext_toolbar_add_val():

    GList * entries = 0;
    entries = ext_toolbar_add_val(entries, "1", "ABCD", false );
    entries = ext_toolbar_add_val(entries, "2", "EFG", false );
    entries = ext_toolbar_add_val(entries, "3", "HIJ", true );
    entries = ext_toolbar_add_val(entries, "4", "KLM", false );

#### 11.5.3.2. Callback for activation of an item

If an item has been activated, the provided callback is being triggered.

    void toolbar_cb(void *toolbar_item, void *item_data, void *user_data)

For EXT_TOOLBAR_BUTTON the callback is triggered upon a click on the button, for EXT_TOOLBAR_BOOLEAN and EXT_TOOLBAR_SELECTOR the callback is triggered with every change of the selection.

For EXT_TOOLBAR_STRING either the return key has to be hit or the apply button pressed.

The parameters of the callback are defined as follows:

toolbar_item
  an element of the type ext_toolbar_t * representing the item that has been activated
item_data
  the data of the item during activation. The content depends on the item type:

- EXT_TOOLBAR_BUTTON - the entry is null
- EXT_TOOLBAR_BOOLEAN - the entry is 0 if the checkbox is unchecked and 1 if it is checked
- EXT_TOOLBAR_STRING - a string representing the context of the textbox. Only valid strings are being passed, it can be safely assumed, that an applied regular expression has been checked.
- EXT_TOOLBAR_SELECTOR - the value of the selected entry

user_data
  the data provided during element registration

#### 11.5.3.3. Sending updates to the toolbar items

A plugin may send updates to the toolbar entry, using one of the following methods. The parameter silent defines, if the registered toolbar callback is triggered by the update or not.

    void ext_toolbar_update_value(ext_toolbar_t * entry, void *data, bool silent)

- EXT_TOOLBAR_BUTTON, EXT_TOOLBAR_STRING - the displayed text (on the button or in the textbox) are being changed, in that case data is expected to be a string
- EXT_TOOLBAR_BOOLEAN - the checkbox value is being changed, to either 0 or 1, in both cases data is expected to be an integer sent by GINT_TO_POINTER(n)
- EXT_TOOLBAR_SELECTOR - the display text to be changed. If no element exists with this text, nothing will happen

        void ext_toolbar_update_data(ext_toolbar_t * entry, void *data, bool silent)

- EXT_TOOLBAR_SELECTOR - change the value list to the one provided with data. Attention! this does not change the list stored within the item just the one in the displayed combobox

    void ext_toolbar_update_data_by_index(ext_toolbar_t * entry, void *data, void *value,
         bool silent)

- EXT_TOOLBAR_SELECTOR - change the display text for the entry with the provided value. Both data and value must be char * pointer.

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