/* plugins.c
 * plugin routines
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0+
 */

#include "config.h"

#ifdef HAVE_PLUGINS

#include <time.h>

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

#include <glib.h>
#include <gmodule.h>

#include <wsutil/filesystem.h>
#include <wsutil/privileges.h>
#include <wsutil/file_util.h>
#include <wsutil/report_message.h>

#include <wsutil/plugins.h>
#include <wsutil/ws_printf.h> /* ws_debug_printf */

typedef struct _plugin {
    GModule        *handle;       /* handle returned by g_module_open */
    gchar          *name;         /* plugin name */
    const gchar    *version;      /* plugin version */
    GString        *types;        /* description with types this plugin supports */
} plugin;

static GHashTable *plugins_table = NULL;

static void
free_plugin(gpointer _p)
{
    plugin *p = (plugin *)_p;
    g_module_close(p->handle);
    g_free(p->name);
    g_string_free(p->types, TRUE);
    g_free(p);
}

/*
 * Add a new plugin type.
 * Takes a callback routine as an argument; it is called for each plugin
 * we find, and handed a handle for the plugin, the name of the plugin,
 * and the version string for the plugin.  The plugin returns TRUE if
 * it's a plugin for that type and FALSE if not.
 */
typedef struct {
    const char *name;
    plugin_check_type_callback check_type;
} plugin_type;

static GSList *plugin_types = NULL;

static void
free_plugin_type(gpointer p, gpointer user_data _U_)
{
    g_free(p);
}

void
add_plugin_type(const char *name, plugin_check_type_callback check_type)
{
    plugin_type *new_type;

    new_type = (plugin_type *)g_malloc(sizeof (plugin_type));
    new_type->name = name;
    new_type->check_type = check_type;
    plugin_types = g_slist_prepend(plugin_types, new_type);
}

static void
call_plugin_callback(gpointer data, gpointer user_data)
{
    plugin_type *type = (plugin_type *)data;
    plugin *new_plug = (plugin *)user_data;

    if (type->check_type(new_plug->handle)) {
        /* The plugin supports this type */
        if (new_plug->types->len > 0)
            g_string_append(new_plug->types, ", ");
        g_string_append(new_plug->types, type->name);
    }
}

static void
plugins_scan_dir(const char *dirname, plugin_load_failure_mode mode)
{
    WS_DIR        *dir;             /* scanned directory */
    WS_DIRENT     *file;            /* current file */
    const char    *name;
    gchar         *filename;        /* current file name */
    GModule       *handle;          /* handle returned by g_module_open */
    gpointer       symbol;
    const char    *plug_version, *plug_release;
    plugin        *new_plug;
    gchar         *dot;

    if (!g_file_test(dirname, G_FILE_TEST_EXISTS) || !g_file_test(dirname, G_FILE_TEST_IS_DIR)) {
        return;
    }

    if ((dir = ws_dir_open(dirname, 0, NULL)) != NULL)
    {
        while ((file = ws_dir_read_name(dir)) != NULL)
        {
            name = ws_dir_get_name(file);

            /*
             * GLib 2.x defines G_MODULE_SUFFIX as the extension used on
             * this platform for loadable modules.
             */
            /* skip anything but files with G_MODULE_SUFFIX */
            dot = strrchr(name, '.');
            if (dot == NULL || strcmp(dot+1, G_MODULE_SUFFIX) != 0)
                continue;

#if WIN32
            if (strncmp(name, "nordic_ble.dll", 14) == 0)
                /*
                 * Skip the Nordic BLE Sniffer dll on WIN32 because
                 * the dissector has been added as internal.
                 */
                continue;
#endif

            /*
             * Check if the same name is already registered.
             */
            if (g_hash_table_lookup(plugins_table, name)) {
                /* Yes, it is. */
                if (mode == REPORT_LOAD_FAILURE) {
                    report_warning("The plugin '%s' was found "
                            "in multiple directories", name);
                }
                continue;
            }

            filename = g_build_filename(dirname, name, (gchar *)NULL);
            handle = g_module_open(filename, G_MODULE_BIND_LOCAL);
            g_free(filename);
            if (handle == NULL)
            {
                /*
                 * Only report load failures if we were asked to.
                 *
                 * XXX - we really should put different types of plugins
                 * (libwiretap, libwireshark) in different subdirectories,
                 * give libwiretap and libwireshark init routines that
                 * load the plugins, and have them scan the appropriate
                 * subdirectories so tha we don't even *try* to, for
                 * example, load libwireshark plugins in programs that
                 * only use libwiretap.
                 */
                if (mode == REPORT_LOAD_FAILURE) {
                    /* g_module_error() provides filename. */
                    report_failure("Couldn't load plugin '%s': %s", name,
                                   g_module_error());
                }
                continue;
            }

            if (!g_module_symbol(handle, "plugin_version", &symbol))
            {
                report_failure("The plugin '%s' has no \"plugin_version\" symbol", name);
                g_module_close(handle);
                continue;
            }
            plug_version = (const char *)symbol;

            if (!g_module_symbol(handle, "plugin_release", &symbol))
            {
                report_failure("The plugin '%s' has no \"plugin_release\" symbol", name);
                g_module_close(handle);
                continue;
            }
            plug_release = (const char *)symbol;
            if (strcmp(plug_release, VERSION_RELEASE) != 0) {
                report_failure("The plugin '%s' was compiled for Wireshark version %s", name, plug_release);
                g_module_close(handle);
                continue;
            }

            new_plug = (plugin *)g_malloc(sizeof(plugin));
            new_plug->handle = handle;
            new_plug->name = g_strdup(name);
            new_plug->version = plug_version;
            new_plug->types = g_string_new(NULL);

            /*
             * Hand the plugin to each of the plugin type callbacks.
             */
            g_slist_foreach(plugin_types, call_plugin_callback, new_plug);

            /*
             * Does this dissector do anything useful?
             */
            if (new_plug->types->len == 0)
            {
                /*
                 * No.
                 *
                 * Only report this failure if we were asked to; it might
                 * just mean that it's a plugin type that this program
                 * doesn't support, such as a libwireshark plugin in
                 * a program that doesn't use libwireshark.
                 *
                 * XXX - we really should put different types of plugins
                 * (libwiretap, libwireshark) in different subdirectories,
                 * give libwiretap and libwireshark init routines that
                 * load the plugins, and have them scan the appropriate
                 * subdirectories so tha we don't even *try* to, for
                 * example, load libwireshark plugins in programs that
                 * only use libwiretap.
                 */
                if (mode == REPORT_LOAD_FAILURE) {
                    report_failure("The plugin '%s' has no registration routines",
                                   name);
                }
                free_plugin(new_plug);
                continue;
            }

            /*
             * OK, add it to the list of plugins.
             */
            g_hash_table_insert(plugins_table, new_plug->name, new_plug);
        }
        ws_dir_close(dir);
    }
}

/*
 * Scan the buildir for plugins.
 */
static void
scan_plugins_build_dir(plugin_load_failure_mode mode)
{
    const char *plugin_dir;
    const char *name;
    char *plugin_dir_path;
    WS_DIR *dir;                /* scanned directory */
    WS_DIRENT *file;            /* current file */

    plugin_dir = get_plugins_dir();
    if ((dir = ws_dir_open(plugin_dir, 0, NULL)) == NULL)
        return;

    plugins_scan_dir(plugin_dir, mode);
    while ((file = ws_dir_read_name(dir)) != NULL)
    {
        name = ws_dir_get_name(file);
        if (strcmp(name, ".") == 0 || strcmp(name, "..") == 0)
            continue;        /* skip "." and ".." */
        /*
         * Get the full path of a ".libs" subdirectory of that
         * directory.
         */
        plugin_dir_path = g_build_filename(plugin_dir, name, ".libs", (gchar *)NULL);
        if (test_for_directory(plugin_dir_path) != EISDIR) {
            /*
             * Either it doesn't refer to a directory or it
             * refers to something that doesn't exist.
             *
             * Assume that means that the plugins are in
             * the subdirectory of the plugin directory, not
             * a ".libs" subdirectory of that subdirectory.
             */
            g_free(plugin_dir_path);
            plugin_dir_path = g_build_filename(plugin_dir, name, (gchar *)NULL);
        }
        plugins_scan_dir(plugin_dir_path, mode);
        g_free(plugin_dir_path);
    }
    ws_dir_close(dir);
}

/*
 * Scan for plugins.
 */
void
scan_plugins(plugin_load_failure_mode mode)
{
    if (!g_module_supported())
        return; /* nothing to do */

    if (plugins_table != NULL)
        return; /* only scan for plugins once */

    plugins_table = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, free_plugin);
    /*
     * Scan the global plugin directory.
     * If we're running from a build directory, scan the "plugins"
     * subdirectory, as that's where plugins are located in an
     * out-of-tree build. If we find subdirectories scan those since
     * they will contain plugins in the case of an in-tree build.
     */
    if (running_in_build_directory())
    {
        scan_plugins_build_dir(mode);
    }
    else
    {
        plugins_scan_dir(get_plugins_dir_with_version(), mode);
    }

    /*
     * If the program wasn't started with special privileges,
     * scan the users plugin directory.  (Even if we relinquish
     * them, plugins aren't safe unless we've *permanently*
     * relinquished them, and we can't do that in Wireshark as,
     * if we need privileges to start capturing, we'd need to
     * reclaim them before each time we start capturing.)
     */
    if (!started_with_special_privs())
    {
        plugins_scan_dir(get_plugins_pers_dir_with_version(), mode);
    }
}

static void
add_plugin_to_descriptions(gpointer key _U_, gpointer value, gpointer user_data)
{
    g_ptr_array_add((GPtrArray *)user_data, value);
}

static int
compare_plugins(gconstpointer _a, gconstpointer _b)
{
    const plugin *a = *(const plugin **)_a;
    const plugin *b = *(const plugin **)_b;

    return strcmp(a->name, b->name);
}

struct description_callback {
    plugin_description_callback callback;
    gpointer callback_data;
};

static void
call_description_callback(gpointer data, gpointer user_data)
{
    plugin *plug = (plugin *)data;
    struct description_callback *desc = (struct description_callback *)user_data;

    desc->callback(plug->name, plug->version, plug->types->str, g_module_name(plug->handle), desc->callback_data);
}

WS_DLL_PUBLIC void
plugins_get_descriptions(plugin_description_callback callback, void *user_data)
{
    GPtrArray *descriptions;
    struct description_callback cb;

    if (!plugins_table)
        return;

    descriptions = g_ptr_array_sized_new(g_hash_table_size(plugins_table));
    g_hash_table_foreach(plugins_table, add_plugin_to_descriptions, descriptions);
    g_ptr_array_sort(descriptions, compare_plugins);
    cb.callback = callback;
    cb.callback_data = user_data;
    g_ptr_array_foreach(descriptions, call_description_callback, &cb);
    g_ptr_array_free(descriptions, FALSE);
}

static void
print_plugin_description(const char *name, const char *version,
                         const char *description, const char *filename,
                         void *user_data _U_)
{
    ws_debug_printf("%s\t%s\t%s\t%s\n", name, version, description, filename);
}

void
plugins_dump_all(void)
{
    plugins_get_descriptions(print_plugin_description, NULL);
}

int
plugins_get_count(void)
{
    if (plugins_table)
        return g_hash_table_size(plugins_table);
    return 0;
}

void
plugins_cleanup(void)
{
    if (plugins_table)
        g_hash_table_destroy(plugins_table);
    g_slist_foreach(plugin_types, free_plugin_type, NULL);
    g_slist_free(plugin_types);
}

#endif /* HAVE_PLUGINS */

/*
 * Editor modelines
 *
 * Local Variables:
 * c-basic-offset: 4
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * ex: set shiftwidth=4 tabstop=8 expandtab:
 * :indentSize=4:tabSize=8:noTabs=true:
 */