text: /* extcap.c
   *
   * Routines for extcap external capture
   * Copyright 2013, Mike Ryan <mikeryan@lacklustre.net>
   *
   * Wireshark - Network traffic analyzer
   * By Gerald Combs <gerald@wireshark.org>
   * Copyright 1998 Gerald Combs
   *
   * SPDX-License-Identifier: GPL-2.0-or-later
   */
  
  #include <config.h>
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #ifdef _WIN32
  #include <windows.h>
  #include <process.h>
  #include <time.h>
  #else
  /* Include for unlink */
  #include <unistd.h>
  #endif
  
  #include <sys/types.h>
  #ifdef HAVE_SYS_WAIT_H
  #include <sys/wait.h>
  #endif
  
  #include <glib.h>
  #include <log.h>
  
  #include <epan/prefs.h>
  
  #include "ui/iface_toolbar.h"
  
  #include <wsutil/file_util.h>
  #include <wsutil/filesystem.h>
  #include <wsutil/ws_pipe.h>
  #include <wsutil/tempfile.h>
  
  #include "capture_opts.h"
  
  #include "extcap.h"
  #include "extcap_parser.h"
  
  #include "version_info.h"
  
  #ifdef _WIN32
  static HANDLE pipe_h = INVALID_HANDLE_VALUE;
  #endif
  
  static void extcap_child_watch_cb(GPid pid, gint status, gpointer user_data);
  
  /* internal container, for all the extcap executables that have been found.
   * Will be resetted if extcap_clear_interfaces() is being explicitly called
   * and is being used for printing information about all extcap interfaces found,
   * as well as storing all sub-interfaces
   */
  static GHashTable * _loaded_interfaces = NULL;
  
  /* Internal container, which maps each ifname to the tool providing it, for faster
   * lookup. The key and string value are owned by this table.
   */
  static GHashTable * _tool_for_ifname = NULL;
  
  /* internal container, for all the extcap executables that have been found
   * and that provides a toolbar with controls to be added to a Interface Toolbar
   */
  static GHashTable *_toolbars = NULL;
  
  /* internal container, to map preference names to pointers that hold preference
   * values. These ensure that preferences can survive extcap if garbage
   * collection, and does not lead to dangling pointers in the prefs subsystem.
   */
  static GHashTable *extcap_prefs_dynamic_vals = NULL;
  
  typedef struct _extcap_callback_info_t
  {
      const gchar * extcap;
      const gchar * ifname;
      gchar * output;
      void * data;
      gchar ** err_str;
  } extcap_callback_info_t;
  
  /* Callback definition for extcap_foreach */
  typedef gboolean(*extcap_cb_t)(extcap_callback_info_t info_structure);
  
  /** GThreadPool does not support pushing new work from a thread while waiting
   * for the thread pool to finish. This data structure tracks ongoing work.
   * See https://gitlab.gnome.org/GNOME/glib/issues/1598 */
  typedef struct thread_pool {
      GThreadPool    *pool;
      gint            count;  /**< Number of tasks that have not finished. */
      GCond           cond;
      GMutex          data_mutex;
  } thread_pool_t;
  
  /**
   * Callback definition for extcap_run_all, invoked with a thread pool (to
   * schedule new tasks), an opaque data parameter, and the output from last task
   * (or NULL if it failed). The output must be freed by the callback function.
   * The implementation MUST be thread-safe.
   */
  typedef void (*extcap_run_cb_t)(thread_pool_t *pool, void *data, char *output);
  
  typedef struct extcap_run_task {
      const char     *extcap_path;
      char          **argv;       /**< NULL-terminated arguments list, freed when the task is completed. */
      extcap_run_cb_t output_cb;
      void           *data;       /** Parameter to be passed to output_cb. */
  } extcap_run_task_t;
  
  typedef struct extcap_iface_info {
      char *ifname;                       /**< Interface name. */
      char *output;                       /**< Output of --extcap-config. */
  } extcap_iface_info_t;
  
  typedef struct extcap_run_extcaps_info {
      char    *extcap_path;               /**< Extcap program path, MUST be the first member.  */
      char    *output;                    /**< Output of --extcap-interfaces. */
      guint   num_interfaces;             /**< Number of discovered interfaces. */
      extcap_iface_info_t *iface_infos;   /**< Per-interface information. */
  } extcap_run_extcaps_info_t;
  
  
  static void extcap_load_interface_list(void);
  
  static gboolean
  thread_pool_push(thread_pool_t *pool, gpointer data, GError **error)
  {
      g_mutex_lock(&pool->data_mutex);
      ++pool->count;
      g_mutex_unlock(&pool->data_mutex);
      return g_thread_pool_push(pool->pool, data, error);
  }
  
  static void
  thread_pool_wait(thread_pool_t *pool)
  {
      g_mutex_lock(&pool->data_mutex);
      while (pool->count != 0) {
          g_cond_wait(&pool->cond, &pool->data_mutex);
      }
      g_cond_clear(&pool->cond);
      g_mutex_unlock(&pool->data_mutex);
      g_mutex_clear(&pool->data_mutex);
  }
  
  GHashTable *
  extcap_loaded_interfaces(void)
  {
      if (prefs.capture_no_extcap)
          return NULL;
  
      if ( !_loaded_interfaces || g_hash_table_size(_loaded_interfaces) == 0 )
          extcap_load_interface_list();
  
      return _loaded_interfaces;
  }
  
  void
  extcap_clear_interfaces(void)
  {
      if ( _loaded_interfaces )
          g_hash_table_destroy(_loaded_interfaces);
      _loaded_interfaces = NULL;
  
      if ( _tool_for_ifname )
          g_hash_table_destroy(_tool_for_ifname);
      _tool_for_ifname = NULL;
  }
  
  /**
   * Obtains a list of extcap program paths. Use g_slist_free_full(paths, g_free)
   * to destroy the list.
   */
  static GSList *
  extcap_get_extcap_paths(void)
  {
      GDir *dir;
      const char *dirname = get_extcap_dir();
      const gchar *file;
      GSList *paths = NULL;
  
      if ((dir = g_dir_open(dirname, 0, NULL)) != NULL) {
          while ((file = g_dir_read_name(dir)) != NULL) {
              /* full path to extcap binary */
              gchar *extcap_path = g_strdup_printf("%s" G_DIR_SEPARATOR_S "%s", dirname, file);
              /* treat anything executable as an extcap binary */
              if (g_file_test(extcap_path, G_FILE_TEST_IS_REGULAR) &&
                  g_file_test(extcap_path, G_FILE_TEST_IS_EXECUTABLE)) {
                  paths = g_slist_append(paths, extcap_path);
              } else {
                  g_free(extcap_path);
              }
  
          }
          g_dir_close(dir);
      }
  
      return paths;
  }
  
  static extcap_interface *
  extcap_find_interface_for_ifname(const gchar *ifname)
  {
      extcap_interface * result = NULL;
  
      if ( !ifname || ! _tool_for_ifname || ! _loaded_interfaces )
          return result;
  
      gchar * extcap_util = (gchar *)g_hash_table_lookup(_tool_for_ifname, ifname);
      if ( ! extcap_util )
          return result;
  
      extcap_info * element = (extcap_info *)g_hash_table_lookup(_loaded_interfaces, extcap_util);
      if ( ! element )
          return result;
  
      GList * walker = element->interfaces;
      while ( walker && walker->data && ! result )
      {
          extcap_interface * interface = (extcap_interface *)walker->data;
          if ( g_strcmp0(interface->call, ifname) == 0 )
          {
              result = interface;
              break;
          }
  
          walker = g_list_next ( walker );
      }
  
      return result;
  }
  
  static void
  extcap_free_toolbar_value(iface_toolbar_value *value)
  {
      if (!value)
      {
          return;
      }
  
      g_free(value->value);
      g_free(value->display);
      g_free(value);
  }
  
  static void
  extcap_free_toolbar_control(iface_toolbar_control *control)
  {
      if (!control)
      {
          return;
      }
  
      g_free(control->display);
      g_free(control->validation);
      g_free(control->tooltip);
      if (control->ctrl_type == INTERFACE_TYPE_STRING) {
          g_free(control->default_value.string);
      }
      g_list_free_full(control->values, (GDestroyNotify)extcap_free_toolbar_value);
      g_free(control);
  }
  
  static void
  extcap_free_toolbar(gpointer data)
  {
      if (!data)
      {
          return;
      }
  
      iface_toolbar *toolbar = (iface_toolbar *)data;
  
      g_free(toolbar->menu_title);
      g_free(toolbar->help);
      g_list_free_full(toolbar->ifnames, g_free);
      g_list_free_full(toolbar->controls, (GDestroyNotify)extcap_free_toolbar_control);
      g_free(toolbar);
  }
  
  static gchar *
  extcap_if_executable(const gchar *ifname)
  {
      extcap_interface *interface = extcap_find_interface_for_ifname(ifname);
      return interface != NULL ? interface->extcap_path : NULL;
  }
  
  static void
  extcap_iface_toolbar_add(const gchar *extcap, iface_toolbar *toolbar_entry)
  {
      char *toolname;
  
      if (!extcap || !toolbar_entry)
      {
          return;
      }
  
      toolname = g_path_get_basename(extcap);
  
      if (!g_hash_table_lookup(_toolbars, toolname))
      {
          g_hash_table_insert(_toolbars, g_strdup(toolname), toolbar_entry);
      }
  
      g_free(toolname);
  }
  
  static gchar **
  extcap_convert_arguments_to_array(GList * arguments)
  {
      gchar ** result = NULL;
      if ( arguments )
      {
          GList * walker = g_list_first(arguments);
          int cnt = 0;
  
          result = (gchar **) g_malloc0(sizeof(gchar *) * (g_list_length(arguments)));
  
          while(walker)
          {
              result[cnt] = g_strdup((const gchar *)walker->data);
              walker = g_list_next(walker);
              cnt++;
          }
      }
      return result;
  }
  
  static void extcap_free_array(gchar ** args, int argc)
  {
      int cnt = 0;
  
      for ( cnt = 0; cnt < argc; cnt++ )
          g_free(args[cnt]);
      g_free(args);
  }
  
  static void
  extcap_free_extcaps_info_array(extcap_run_extcaps_info_t *infos, guint count)
  {
      for (guint i = 0; i < count; i++) {
          g_free(infos[i].extcap_path);
          g_free(infos[i].output);
          for (guint j = 0; j < infos[i].num_interfaces; j++) {
              extcap_iface_info_t *iface_info = &infos[i].iface_infos[j];
              g_free(iface_info->ifname);
              g_free(iface_info->output);
          }
          g_free(infos[i].iface_infos);
      }
      g_free(infos);
  }
  
  static void
  extcap_run_one(const extcap_interface *interface, GList *arguments, extcap_cb_t cb, void *user_data, char **err_str)
  {
      const char *dirname = get_extcap_dir();
      gchar **args = extcap_convert_arguments_to_array(arguments);
      int cnt = g_list_length(arguments);
      gchar *command_output;
      if (ws_pipe_spawn_sync(dirname, interface->extcap_path, cnt, args, &command_output)) {
          extcap_callback_info_t cb_info = {
              .ifname = interface->call,
              .extcap = interface->extcap_path,
              .output = command_output,
              .data = user_data,
              .err_str = err_str,
          };
          cb(cb_info);
          g_free(command_output);
      }
      extcap_free_array(args, cnt);
  }
  
  /** Thread callback to run an extcap program and pass its output. */
  static void
  extcap_thread_callback(gpointer data, gpointer user_data)
  {
      extcap_run_task_t *task = (extcap_run_task_t *)data;
      thread_pool_t *pool = (thread_pool_t *)user_data;
      const char *dirname = get_extcap_dir();
  
      char *command_output;
      if (ws_pipe_spawn_sync(dirname, task->extcap_path, g_strv_length(task->argv), task->argv, &command_output)) {
          task->output_cb(pool, task->data, command_output);
      } else {
          task->output_cb(pool, task->data, NULL);
      }
      g_strfreev(task->argv);
      g_free(task);
  
      // Notify when all tasks are completed and no new subtasks were created.
      g_mutex_lock(&pool->data_mutex);
      if (--pool->count == 0) {
          g_cond_signal(&pool->cond);
      }
      g_mutex_unlock(&pool->data_mutex);
  }
  
  /*
   * Run all extcap programs with the given arguments list, invoke the callback to
   * do some processing and return the results.
   *
   * @param [IN] argv NULL-terminated arguments list.
   * @param [IN] output_cb Thread callback function that receives the output.
   * @param [IN] data_size Size of the per-program information that will be returned.
   * @param [OUT] count Size of the returned array.
   * @return Array of information or NULL if there are none. The first member of
   * each element (char *extcap_path) must be freed.
   */
  static gpointer
  extcap_run_all(const char *argv[], extcap_run_cb_t output_cb, gsize data_size, guint *count)
  {
      /* Need enough space for at least 'extcap_path'. */
      g_assert(data_size >= sizeof(char *));
  
      GSList *paths = extcap_get_extcap_paths();
      int i = 0;
  #if GLIB_CHECK_VERSION(2,36,0)
      int max_threads = (int)g_get_num_processors();
  #else
      // If the number of processors is unavailable, just use some sane maximum.
      // extcap should not be CPU bound, so -1 could also be used for unlimited.
      int max_threads = 8;
  #endif
  
      if (!paths) {
          *count = 0;
          return NULL;
      }
  
      guint64 start_time = g_get_monotonic_time();
      guint paths_count = g_slist_length(paths);
      /* GSList is not thread-safe, so pre-allocate an array instead. */
      gpointer infos = g_malloc0_n(paths_count, data_size);
  
      thread_pool_t pool;
      pool.pool = g_thread_pool_new(extcap_thread_callback, &pool, max_threads, FALSE, NULL);
      pool.count = 0;
      g_cond_init(&pool.cond);
      g_mutex_init(&pool.data_mutex);
  
      for (GSList *path = paths; path; path = g_slist_next(path), i++) {
          extcap_run_task_t *task = g_new0(extcap_run_task_t, 1);
  
          task->extcap_path = (char *)path->data;
          task->argv = g_strdupv((char **)argv);
          task->output_cb = output_cb;
          task->data = ((char *)infos) + (i * data_size);
          *((char **)task->data) = (char *)path->data;
  
          thread_pool_push(&pool, task, NULL);
      }
      g_slist_free(paths);    /* Note: the contents are transferred to 'infos'. */
  
      /* Wait for all (sub)tasks to complete. */
      thread_pool_wait(&pool);
      g_thread_pool_free(pool.pool, FALSE, TRUE);
  
      g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "extcap: completed discovery of %d tools in %.3fms",
              paths_count, (g_get_monotonic_time() - start_time) / 1000.0);
      *count = paths_count;
      return infos;
  }
  
  static void extcap_free_dlt(gpointer d, gpointer user_data _U_)
  {
      if (d == NULL)
      {
          return;
      }
  
      g_free(((extcap_dlt *)d)->name);
      g_free(((extcap_dlt *)d)->display);
      g_free(d);
  }
  
  static void extcap_free_dlts(GList *dlts)
  {
      g_list_foreach(dlts, extcap_free_dlt, NULL);
      g_list_free(dlts);
  }
  
  static gboolean cb_dlt(extcap_callback_info_t cb_info)
  {
      GList *dlts = NULL, *temp = NULL;
  
      if_capabilities_t *caps;
      GList *linktype_list = NULL;
      data_link_info_t *data_link_info;
      extcap_dlt *dlt_item;
  
      dlts = extcap_parse_dlts(cb_info.output);
      temp = dlts;
  
      g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "Extcap pipe %s ", cb_info.extcap);
  
      /*
       * Allocate the interface capabilities structure.
       */
      caps = (if_capabilities_t *) g_malloc(sizeof * caps);
      caps->can_set_rfmon = FALSE;
      caps->timestamp_types = NULL;
  
      while (dlts)
      {
          dlt_item = (extcap_dlt *)dlts->data;
          if (dlt_item)
          {
              g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG,
                    "  DLT %d name=\"%s\" display=\"%s\" ", dlt_item->number,
                    dlt_item->name, dlt_item->display);
  
              data_link_info = g_new(data_link_info_t, 1);
              data_link_info->dlt = dlt_item->number;
              data_link_info->name = g_strdup(dlt_item->name);
              data_link_info->description = g_strdup(dlt_item->display);
              linktype_list = g_list_append(linktype_list, data_link_info);
          }
  
          dlts = g_list_next(dlts);
      }
  
      /* Check to see if we built a list */
      if (linktype_list != NULL && cb_info.data != NULL)
      {
          caps->data_link_types = linktype_list;
          *(if_capabilities_t **) cb_info.data = caps;
      }
      else
      {
          if (cb_info.err_str)
          {
              g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "  returned no DLTs");
              *(cb_info.err_str) = g_strdup("Extcap returned no DLTs");
          }
          g_free(caps);
      }
  
      extcap_free_dlts(temp);
  
      return FALSE;
  }
  
  if_capabilities_t *
  extcap_get_if_dlts(const gchar *ifname, char **err_str)
  {
      GList * arguments = NULL;
      if_capabilities_t *caps = NULL;
  
      if (err_str != NULL)
      {
          *err_str = NULL;
      }
  
      extcap_interface *interface = extcap_find_interface_for_ifname(ifname);
      if (interface)
      {
          arguments = g_list_append(arguments, g_strdup(EXTCAP_ARGUMENT_LIST_DLTS));
          arguments = g_list_append(arguments, g_strdup(EXTCAP_ARGUMENT_INTERFACE));
          arguments = g_list_append(arguments, g_strdup(ifname));
  
          extcap_run_one(interface, arguments, cb_dlt, &caps, err_str);
  
          g_list_free_full(arguments, g_free);
      }
  
      return caps;
  }
  
  static void extcap_free_interface(gpointer i)
  {
  
      extcap_interface *interface = (extcap_interface *)i;
  
      if (i == NULL)
      {
          return;
      }
  
      g_free(interface->call);
      g_free(interface->display);
      g_free(interface->version);
      g_free(interface->help);
      g_free(interface->extcap_path);
      g_free(interface);
  }
  
  static void extcap_free_interfaces(GList *interfaces)
  {
      if (interfaces == NULL)
      {
          return;
      }
  
      g_list_free_full(interfaces, extcap_free_interface);
  }
  
  static gint
  if_info_compare(gconstpointer a, gconstpointer b)
  {
      gint comp = 0;
      const if_info_t *if_a = (const if_info_t *)a;
      const if_info_t *if_b = (const if_info_t *)b;
  
      if ((comp = g_strcmp0(if_a->name, if_b->name)) == 0)
      {
          return g_strcmp0(if_a->friendly_name, if_b->friendly_name);
      }
  
      return comp;
  }
  
  gchar *
  extcap_get_help_for_ifname(const char *ifname)
  {
      extcap_interface *interface = extcap_find_interface_for_ifname(ifname);
      return interface != NULL ? interface->help : NULL;
  }
  
  GList *
  append_extcap_interface_list(GList *list, char **err_str _U_)
  {
      GList *interface_list = NULL;
      extcap_interface *data = NULL;
      GList *ifutilkeys_head = NULL, *ifutilkeys = NULL;
  
      if (prefs.capture_no_extcap)
          return list;
  
      /* Update the extcap interfaces and get a list of their if_infos */
      if ( !_loaded_interfaces || g_hash_table_size(_loaded_interfaces) == 0 )
          extcap_load_interface_list();
  
      ifutilkeys_head = g_hash_table_get_keys(_loaded_interfaces);
      ifutilkeys = ifutilkeys_head;
      while ( ifutilkeys && ifutilkeys->data )
      {
          extcap_info * extinfo =
                  (extcap_info *) g_hash_table_lookup(_loaded_interfaces, (gchar *)ifutilkeys->data);
          GList * walker = extinfo->interfaces;
          while ( walker && walker->data )
          {
              interface_list = g_list_append(interface_list, walker->data);
              walker = g_list_next(walker);
          }
  
          ifutilkeys = g_list_next(ifutilkeys);
      }
      g_list_free(ifutilkeys_head);
  
      /* Sort that list */
      interface_list = g_list_sort(interface_list, if_info_compare);
  
      /* Append the interfaces in that list to the list we're handed. */
      while (interface_list != NULL)
      {
          GList *entry = g_list_first(interface_list);
          data = (extcap_interface *)entry->data;
          interface_list = g_list_delete_link(interface_list, entry);
  
          if_info_t * if_info = g_new0(if_info_t, 1);
          if_info->name = g_strdup(data->call);
          if_info->friendly_name = g_strdup(data->display);
  
          if_info->type = IF_EXTCAP;
  
          if_info->extcap = g_strdup(data->extcap_path);
  
          list = g_list_append(list, if_info);
      }
  
      return list;
  }
  
  void extcap_register_preferences(void)
  {
      if (prefs.capture_no_extcap)
          return;
  
      module_t *dev_module = prefs_find_module("extcap");
  
      if (!dev_module)
      {
          return;
      }
  
      // Will load information about extcaps and their supported config.
      extcap_load_interface_list();
  }
  
  /**
   * Releases the dynamic preference value pointers. Must not be called before
   * prefs_cleanup since these pointers could still be in use.
   */
  void extcap_cleanup(void)
  {
      if (extcap_prefs_dynamic_vals)
          g_hash_table_destroy(extcap_prefs_dynamic_vals);
  
      if (_loaded_interfaces)
          g_hash_table_destroy(_loaded_interfaces);
  
      if (_tool_for_ifname)
          g_hash_table_destroy(_tool_for_ifname);
  }
  
  /**
   * Obtains a pointer which can store a value for the given preference name.
   * The preference name that can be passed to the prefs API is stored into
   * 'prefs_name'.
   *
   * Extcap interfaces (and their preferences) are dynamic, they can be created
   * and destroyed at will. Thus their data structures are insufficient to pass to
   * the preferences APIs which require pointers which are valid until the
   * preferences are removed (at exit).
   */
  static gchar **extcap_prefs_dynamic_valptr(const char *name, char **pref_name)
  {
      gchar **valp;
      if (!extcap_prefs_dynamic_vals)
      {
          /* Initialize table only as needed, most preferences are not dynamic */
          extcap_prefs_dynamic_vals = g_hash_table_new_full(g_str_hash, g_str_equal,
                                      g_free, g_free);
      }
      if (!g_hash_table_lookup_extended(extcap_prefs_dynamic_vals, name,
                                        (gpointer *)pref_name, (gpointer *)&valp))
      {
          /* New dynamic pref, allocate, initialize and store. */
          valp = g_new0(gchar *, 1);
          *pref_name = g_strdup(name);
          g_hash_table_insert(extcap_prefs_dynamic_vals, *pref_name, valp);
      }
      return valp;
  }
  
  void extcap_free_if_configuration(GList *list, gboolean free_args)
  {
      GList *elem, *sl;
  
      for (elem = g_list_first(list); elem; elem = elem->next)
      {
          if (elem->data != NULL)
          {
              sl = g_list_first((GList *)elem->data);
              if (free_args)
              {
                  extcap_free_arg_list(sl);
              }
              else
              {
                  g_list_free(sl);
              }
          }
      }
      g_list_free(list);
  }
  
  struct preference *
  extcap_pref_for_argument(const gchar *ifname, struct _extcap_arg *arg)
  {
      struct preference *pref = NULL;
  
      GRegex *regex_name = g_regex_new("[-]+", (GRegexCompileFlags) 0, (GRegexMatchFlags) 0, NULL);
      GRegex *regex_ifname = g_regex_new("(?![a-zA-Z0-9_]).", (GRegexCompileFlags) 0, (GRegexMatchFlags) 0, NULL);
      if (regex_name && regex_ifname)
      {
          if (prefs_find_module("extcap"))
          {
              gchar *pref_name = g_regex_replace(regex_name, arg->call, strlen(arg->call), 0, "", (GRegexMatchFlags) 0, NULL);
              gchar *ifname_underscore = g_regex_replace(regex_ifname, ifname, strlen(ifname), 0, "_", (GRegexMatchFlags) 0, NULL);
              gchar *ifname_lowercase = g_ascii_strdown(ifname_underscore, -1);
              gchar *pref_ifname = g_strconcat(ifname_lowercase, ".", pref_name, NULL);
  
              pref = prefs_find_preference(prefs_find_module("extcap"), pref_ifname);
  
              g_free(pref_name);
              g_free(ifname_underscore);
              g_free(ifname_lowercase);
              g_free(pref_ifname);
          }
      }
      if (regex_name)
      {
          g_regex_unref(regex_name);
      }
      if (regex_ifname)
      {
          g_regex_unref(regex_ifname);
      }
  
      return pref;
  }
  
  static gboolean cb_preference(extcap_callback_info_t cb_info)
  {
      GList *arguments = NULL;
      GList **il = (GList **) cb_info.data;
      module_t *dev_module = NULL;
  
      arguments = extcap_parse_args(cb_info.output);
  
      dev_module = prefs_find_module("extcap");
  
      if (dev_module)
      {
          GList *walker = arguments;
  
          GRegex *regex_name = g_regex_new("[-]+", (GRegexCompileFlags) 0, (GRegexMatchFlags) 0, NULL);
          GRegex *regex_ifname = g_regex_new("(?![a-zA-Z0-9_]).", (GRegexCompileFlags) 0, (GRegexMatchFlags) 0, NULL);
          if (regex_name && regex_ifname)
          {
              while (walker != NULL)
              {
                  extcap_arg *arg = (extcap_arg *)walker->data;
                  arg->device_name = g_strdup(cb_info.ifname);
  
                  if (arg->save)
                  {
                      struct preference *pref = NULL;
  
                      gchar *pref_name = g_regex_replace(regex_name, arg->call, strlen(arg->call), 0, "", (GRegexMatchFlags) 0, NULL);
                      gchar *ifname_underscore = g_regex_replace(regex_ifname, cb_info.ifname, strlen(cb_info.ifname), 0, "_", (GRegexMatchFlags) 0, NULL);
                      gchar *ifname_lowercase = g_ascii_strdown(ifname_underscore, -1);
                      gchar *pref_ifname = g_strconcat(ifname_lowercase, ".", pref_name, NULL);
  
                      if ((pref = prefs_find_preference(dev_module, pref_ifname)) == NULL)
                      {
                          char *pref_name_for_prefs;
                          char *pref_title = wmem_strdup(wmem_epan_scope(), arg->display);
  
                          arg->pref_valptr = extcap_prefs_dynamic_valptr(pref_ifname, &pref_name_for_prefs);
                          /* Set an initial value if any (the string will be copied at registration) */
                          if (arg->default_complex)
                          {
                              *arg->pref_valptr = arg->default_complex->_val;
                          }
  
                          prefs_register_string_preference(dev_module, pref_name_for_prefs,
                                                           pref_title, pref_title, (const char **)arg->pref_valptr);
                      }
                      else
                      {
                          /* Been here before, restore stored value */
                          if (arg->pref_valptr == NULL)
                          {
                              arg->pref_valptr = (gchar**)g_hash_table_lookup(extcap_prefs_dynamic_vals, pref_ifname);
                          }
                      }
  
                      g_free(pref_name);
                      g_free(ifname_underscore);
                      g_free(ifname_lowercase);
                      g_free(pref_ifname);
                  }
  
                  walker = g_list_next(walker);
              }
          }
          if (regex_name)
          {
              g_regex_unref(regex_name);
          }
          if (regex_ifname)
          {
              g_regex_unref(regex_ifname);
          }
      }
  
      *il = g_list_append(*il, arguments);
  
      /* By returning false, extcap_foreach will break on first found */
      return TRUE;
  }
  
  GList *
  extcap_get_if_configuration(const char *ifname)
  {
      GList * arguments = NULL;
      GList *ret = NULL;
  
      extcap_interface *interface = extcap_find_interface_for_ifname(ifname);
      if (interface)
      {
          g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "Extcap path %s",
                get_extcap_dir());
  
          arguments = g_list_append(arguments, g_strdup(EXTCAP_ARGUMENT_CONFIG));
          arguments = g_list_append(arguments, g_strdup(EXTCAP_ARGUMENT_INTERFACE));
          arguments = g_list_append(arguments, g_strdup(ifname));
  
          extcap_run_one(interface, arguments, cb_preference, &ret, NULL);
  
          g_list_free_full(arguments, g_free);
      }
  
      return ret;
  }
  
  static gboolean cb_reload_preference(extcap_callback_info_t cb_info)
  {
      GList *arguments = NULL, * walker = NULL;
      GList **il = (GList **) cb_info.data;
  
      arguments = extcap_parse_values(cb_info.output);
  
      walker = g_list_first(arguments);
      while (walker != NULL)
      {
          extcap_value * val = (extcap_value *)walker->data;
          *il = g_list_append(*il, val);
          walker = g_list_next(walker);
      }
      g_list_free(arguments);
  
      /* By returning false, extcap_foreach will break on first found */
      return FALSE;
  }
  
  GList *
  extcap_get_if_configuration_values(const char * ifname, const char * argname, GHashTable *arguments)
  {
      GList * args = NULL;
      GList *ret = NULL;
  
      extcap_interface *interface = extcap_find_interface_for_ifname(ifname);
      if (interface)
      {
          g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "Extcap path %s",
                get_extcap_dir());
  
          args = g_list_append(args, g_strdup(EXTCAP_ARGUMENT_CONFIG));
          args = g_list_append(args, g_strdup(EXTCAP_ARGUMENT_INTERFACE));
          args = g_list_append(args, g_strdup(ifname));
          args = g_list_append(args, g_strdup(EXTCAP_ARGUMENT_RELOAD_OPTION));
          args = g_list_append(args, g_strdup(argname));
  
          if ( arguments )
          {
              GList * keys = g_hash_table_get_keys(arguments);
              while ( keys )
              {
                  const gchar * key_data = (const gchar *)keys->data;
                  args = g_list_append(args, g_strdup(key_data));
                  args = g_list_append(args, g_strdup((const gchar *)g_hash_table_lookup(arguments, key_data)));
                  keys = g_list_next(keys);
              }
          }
  
          extcap_run_one(interface, args, cb_reload_preference, &ret, NULL);
  
          g_list_free_full(args, g_free);
      }
  
      return ret;
  }
  
  /**
   * If is_required is FALSE: returns TRUE if the extcap interface has
   * configurable options.
   * If is_required is TRUE: returns TRUE when the extcap interface has
   * configurable options that required modification. (For example, when an
   * argument is required but empty.)
   */
  gboolean
  extcap_has_configuration(const char *ifname, gboolean is_required)
  {
      GList *arguments = 0;
      GList *walker = 0, * item = 0;
  
      gboolean found = FALSE;
  
      arguments = extcap_get_if_configuration(ifname);
      walker = g_list_first(arguments);
  
      while (walker != NULL && !found)
      {
          item = g_list_first((GList *)(walker->data));
          while (item != NULL && !found)
          {
              if ((extcap_arg *)(item->data) != NULL)
              {
                  extcap_arg *arg = (extcap_arg *)(item->data);
                  /* Should required options be present, or any kind of options */
                  if (!is_required)
                  {
                      found = TRUE;
                  }
                  else if (arg->is_required)
                  {
                      const gchar *stored = NULL;
                      const gchar *defval = NULL;
  
                      if (arg->pref_valptr != NULL)
                      {
                          stored = *arg->pref_valptr;
                      }
  
                      if (arg->default_complex != NULL && arg->default_complex->_val != NULL)
                      {
                          defval = arg->default_complex->_val;
                      }
  
                      if (arg->is_required)
                      {
                          /* If stored and defval is identical and the argument is required,
                           * configuration is needed */
                          if (defval && stored && g_strcmp0(stored, defval) == 0)
                          {
                              found = TRUE;
                          }
                          else if (!defval && (!stored || !*stored))
                          {
                              found = TRUE;
                          }
                      }
  
                      if (arg->arg_type == EXTCAP_ARG_FILESELECT)
                      {
                          if (arg->fileexists && !(file_exists(defval) || file_exists(stored)))
                          {
                              found = TRUE;
                          }
                      }
                  }
              }
  
              item = item->next;
          }
          walker = walker->next;
      }
      extcap_free_if_configuration(arguments, TRUE);
  
      return found;
  }
  
  static gboolean cb_verify_filter(extcap_callback_info_t cb_info)
  {
      extcap_filter_status *status = (extcap_filter_status *)cb_info.data;
      size_t output_size, i;
  
      output_size = strlen(cb_info.output);
      if (output_size == 0) {
          *status = EXTCAP_FILTER_VALID;
      } else {
          *status = EXTCAP_FILTER_INVALID;
          for (i = 0; i < output_size; i++) {
              if (cb_info.output[i] == '\n' || cb_info.output[i] == '\r') {
                  cb_info.output[i] = '\0';
                  break;
              }
          }
          *cb_info.err_str = g_strdup(cb_info.output);
      }
  
      return TRUE;
  }
  
  extcap_filter_status
  extcap_verify_capture_filter(const char *ifname, const char *filter, gchar **err_str)
  {
      GList * arguments = NULL;
      extcap_filter_status status = EXTCAP_FILTER_UNKNOWN;
  
      extcap_interface *interface = extcap_find_interface_for_ifname(ifname);
      if (interface)
      {
          g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "Extcap path %s",
                get_extcap_dir());
  
          arguments = g_list_append(arguments, g_strdup(EXTCAP_ARGUMENT_CAPTURE_FILTER));
          arguments = g_list_append(arguments, g_strdup(filter));
          arguments = g_list_append(arguments, g_strdup(EXTCAP_ARGUMENT_INTERFACE));
          arguments = g_list_append(arguments, g_strdup(ifname));
  
          extcap_run_one(interface, arguments, cb_verify_filter, &status, err_str);
          g_list_free_full(arguments, g_free);
      }
  
      return status;
  }
  
  gboolean
  extcap_has_toolbar(const char *ifname)
  {
      if (!iface_toolbar_use())
      {
          return FALSE;
      }
  
      GList *toolbar_list = g_hash_table_get_values (_toolbars);
      for (GList *walker = toolbar_list; walker; walker = walker->next)
      {
          iface_toolbar *toolbar = (iface_toolbar *) walker->data;
          if (g_list_find_custom(toolbar->ifnames, ifname, (GCompareFunc) strcmp))
          {
              return TRUE;
          }
      }
  
      return FALSE;
  }
  
  void extcap_if_cleanup(capture_options *capture_opts, gchar **errormsg)
  {
      interface_options *interface_opts;
      ws_pipe_t *pipedata;
      guint icnt = 0;
      gboolean overwrite_exitcode;
      gchar *buffer;
  #define STDERR_BUFFER_SIZE 1024
  
      for (icnt = 0; icnt < capture_opts->ifaces->len; icnt++)
      {
          interface_opts = &g_array_index(capture_opts->ifaces, interface_options,
                                         icnt);
  
          /* skip native interfaces */
          if (interface_opts->if_type != IF_EXTCAP)
          {
              continue;
          }
  
          overwrite_exitcode = FALSE;
  
          g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG,
                "Extcap [%s] - Cleaning up fifo: %s; PID: %d", interface_opts->name,
                interface_opts->extcap_fifo, interface_opts->extcap_pid);
  #ifdef _WIN32
          if (interface_opts->extcap_pipe_h != INVALID_HANDLE_VALUE)
          {
              g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG,
                    "Extcap [%s] - Closing pipe", interface_opts->name);
              FlushFileBuffers(interface_opts->extcap_pipe_h);
              DisconnectNamedPipe(interface_opts->extcap_pipe_h);
              CloseHandle(interface_opts->extcap_pipe_h);
              interface_opts->extcap_pipe_h = INVALID_HANDLE_VALUE;
          }
          if (interface_opts->extcap_control_in_h != INVALID_HANDLE_VALUE)
          {
              g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG,
                    "Extcap [%s] - Closing control_in pipe", interface_opts->name);
              FlushFileBuffers(interface_opts->extcap_control_in_h);
              DisconnectNamedPipe(interface_opts->extcap_control_in_h);
              CloseHandle(interface_opts->extcap_control_in_h);
              interface_opts->extcap_control_in_h = INVALID_HANDLE_VALUE;
          }
          if (interface_opts->extcap_control_out_h != INVALID_HANDLE_VALUE)
          {
              g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG,
                    "Extcap [%s] - Closing control_out pipe", interface_opts->name);
              FlushFileBuffers(interface_opts->extcap_control_out_h);
              DisconnectNamedPipe(interface_opts->extcap_control_out_h);
              CloseHandle(interface_opts->extcap_control_out_h);
              interface_opts->extcap_control_out_h = INVALID_HANDLE_VALUE;
          }
  #else
          if (interface_opts->extcap_fifo != NULL && file_exists(interface_opts->extcap_fifo))
          {
              /* the fifo will not be freed here, but with the other capture_opts in capture_sync */
              ws_unlink(interface_opts->extcap_fifo);
              interface_opts->extcap_fifo = NULL;
          }
          if (interface_opts->extcap_control_in && file_exists(interface_opts->extcap_control_in))
          {
              ws_unlink(interface_opts->extcap_control_in);
              interface_opts->extcap_control_in = NULL;
          }
          if (interface_opts->extcap_control_out && file_exists(interface_opts->extcap_control_out))
          {
              ws_unlink(interface_opts->extcap_control_out);
              interface_opts->extcap_control_out = NULL;
          }
  #endif
          /* Maybe the client closed and removed fifo, but ws should check if
           * pid should be closed */
          g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG,
                "Extcap [%s] - Closing spawned PID: %d", interface_opts->name,
                interface_opts->extcap_pid);
  
          pipedata = (ws_pipe_t *) interface_opts->extcap_pipedata;
          if (pipedata)
          {
              if (pipedata->stderr_fd > 0)
              {
                  buffer = (gchar *)g_malloc0(STDERR_BUFFER_SIZE + 1);
                  ws_read_string_from_pipe(ws_get_pipe_handle(pipedata->stderr_fd), buffer, STDERR_BUFFER_SIZE + 1);
                  if (strlen(buffer) > 0)
                  {
                      pipedata->stderr_msg = g_strdup(buffer);
                      pipedata->exitcode = 1;
                  }
                  g_free(buffer);
              }
  
  #ifndef _WIN32
              /* Final child watch may not have been called */
              if (interface_opts->extcap_child_watch > 0)
              {
                  extcap_child_watch_cb(pipedata->pid, 0, capture_opts);
                  /* it will have changed in extcap_child_watch_cb */
                  interface_opts = &g_array_index(capture_opts->ifaces, interface_options,
                                                 icnt);
              }
  #endif
  
              if (pipedata->stderr_msg != NULL)
              {
                  overwrite_exitcode = TRUE;
              }
  
              if (overwrite_exitcode || pipedata->exitcode != 0)
              {
                  if (pipedata->stderr_msg != NULL)
                  {
                      if (*errormsg == NULL)
                      {
                          *errormsg = g_strdup_printf("Error by extcap pipe: %s", pipedata->stderr_msg);
                      }
                      else
                      {
                          gchar *temp = g_strconcat(*errormsg, "\nError by extcap pipe: " , pipedata->stderr_msg, NULL);
                          g_free(*errormsg);
                          *errormsg = temp;
                      }
                      g_free(pipedata->stderr_msg);
                  }
  
                  pipedata->stderr_msg = NULL;
                  pipedata->exitcode = 0;
              }
          }
  
          if (interface_opts->extcap_child_watch > 0)
          {
              g_source_remove(interface_opts->extcap_child_watch);
              interface_opts->extcap_child_watch = 0;
          }
  
          if (pipedata) {
              if (pipedata->stdout_fd > 0)
              {
                  ws_close(pipedata->stdout_fd);
              }
  
              if (pipedata->stderr_fd > 0)
              {
                  ws_close(pipedata->stderr_fd);
              }
  
              if (interface_opts->extcap_pid != WS_INVALID_PID)
              {
                  ws_pipe_close(pipedata);
                  interface_opts->extcap_pid = WS_INVALID_PID;
  
                  g_free(pipedata);
                  interface_opts->extcap_pipedata = NULL;
              }
          }
      }
  }
  
  static gboolean
  extcap_add_arg_and_remove_cb(gpointer key, gpointer value, gpointer data)
  {
      GPtrArray *args = (GPtrArray *)data;
  
      if (key != NULL)
      {
          g_ptr_array_add(args, g_strdup((const gchar *)key));
  
          if (value != NULL)
          {
              g_ptr_array_add(args, g_strdup((const gchar *)value));
          }
  
          return TRUE;
      }
  
      return FALSE;
  }
  
  void extcap_child_watch_cb(GPid pid, gint status, gpointer user_data)
  {
      guint i;
      interface_options *interface_opts;
      ws_pipe_t *pipedata = NULL;
      capture_options *capture_opts = (capture_options *)(user_data);
  
      if (capture_opts == NULL || capture_opts->ifaces == NULL || capture_opts->ifaces->len == 0)
      {
          return;
      }
  
      /* Close handle to child process. */
      g_spawn_close_pid(pid);
  
      /* Update extcap_pid in interface options structure. */
      for (i = 0; i < capture_opts->ifaces->len; i++)
      {
          interface_opts = &g_array_index(capture_opts->ifaces, interface_options, i);
          if (interface_opts->extcap_pid == pid)
          {
              pipedata = (ws_pipe_t *)interface_opts->extcap_pipedata;
              if (pipedata != NULL)
              {
                  interface_opts->extcap_pid = WS_INVALID_PID;
                  pipedata->exitcode = 0;
  #ifndef _WIN32
                  if (WIFEXITED(status))
                  {
                      if (WEXITSTATUS(status) != 0)
                      {
                          pipedata->exitcode = WEXITSTATUS(status);
                      }
                  }
                  else
                  {
                      pipedata->exitcode = G_SPAWN_ERROR_FAILED;
                  }
  #else
                  if (status != 0)
                  {
                      pipedata->exitcode = status;
                  }
  #endif
                  if (status == 0 && pipedata->stderr_msg != NULL)
                  {
                      pipedata->exitcode = 1;
                  }
              }
              g_source_remove(interface_opts->extcap_child_watch);
              interface_opts->extcap_child_watch = 0;
              break;
          }
      }
  }
  
  static
  GPtrArray *extcap_prepare_arguments(interface_options *interface_opts)
  {
      GPtrArray *result = NULL;
  
      if (interface_opts->if_type == IF_EXTCAP)
      {
          result = g_ptr_array_new();
  
  #define add_arg(X) g_ptr_array_add(result, g_strdup(X))
  
          add_arg(interface_opts->extcap);
          add_arg(EXTCAP_ARGUMENT_RUN_CAPTURE);
          add_arg(EXTCAP_ARGUMENT_INTERFACE);
          add_arg(interface_opts->name);
          if (interface_opts->cfilter && strlen(interface_opts->cfilter) > 0)
          {
              add_arg(EXTCAP_ARGUMENT_CAPTURE_FILTER);
              add_arg(interface_opts->cfilter);
          }
          add_arg(EXTCAP_ARGUMENT_RUN_PIPE);
          add_arg(interface_opts->extcap_fifo);
          if (interface_opts->extcap_control_in)
          {
              add_arg(EXTCAP_ARGUMENT_CONTROL_OUT);
              add_arg(interface_opts->extcap_control_in);
          }
          if (interface_opts->extcap_control_out)
          {
              add_arg(EXTCAP_ARGUMENT_CONTROL_IN);
              add_arg(interface_opts->extcap_control_out);
          }
          if (interface_opts->extcap_args == NULL || g_hash_table_size(interface_opts->extcap_args) == 0)
          {
              /* User did not perform interface configuration.
               *
               * Check if there are any boolean flags that are set by default
               * and hence their argument should be added.
               */
              GList *arglist;
              GList *elem;
  
              arglist = extcap_get_if_configuration(interface_opts->name);
              for (elem = g_list_first(arglist); elem; elem = elem->next)
              {
                  GList *arg_list;
                  extcap_arg *arg_iter;
  
                  if (elem->data == NULL)
                  {
                      continue;
                  }
  
                  arg_list = g_list_first((GList *)elem->data);
                  while (arg_list != NULL)
                  {
                      const gchar *stored = NULL;
                      /* In case of boolflags only first element in arg_list is relevant. */
                      arg_iter = (extcap_arg *)(arg_list->data);
                      if (arg_iter->pref_valptr != NULL)
                      {
                          stored = *arg_iter->pref_valptr;
                      }
  
                      if (arg_iter->arg_type == EXTCAP_ARG_BOOLFLAG)
                      {
                          if (extcap_complex_get_bool(arg_iter->default_complex))
                          {
                              add_arg(arg_iter->call);
                          }
                          else if (g_strcmp0(stored, "true") == 0)
                          {
                              add_arg(arg_iter->call);
                          }
                      }
                      else
                      {
                          if (stored && strlen(stored) > 0) {
                              add_arg(arg_iter->call);
                              add_arg(stored);
                          }
                      }
  
                      arg_list = arg_list->next;
                  }
              }
  
              extcap_free_if_configuration(arglist, TRUE);
          }
          else
          {
              g_hash_table_foreach_remove(interface_opts->extcap_args, extcap_add_arg_and_remove_cb, result);
          }
          add_arg(NULL);
  #undef add_arg
  
      }
  
      return result;
  }
  
  static void ptr_array_free(gpointer data, gpointer user_data _U_)
  {
      g_free(data);
  }
  
  /* call mkfifo for each extcap,
   * returns FALSE if there's an error creating a FIFO */
  gboolean
  extcap_init_interfaces(capture_options *capture_opts)
  {
      guint i;
      interface_options *interface_opts;
      ws_pipe_t *pipedata;
  
      for (i = 0; i < capture_opts->ifaces->len; i++)
      {
          GPtrArray *args = NULL;
          GPid pid = WS_INVALID_PID;
  
          interface_opts = &g_array_index(capture_opts->ifaces, interface_options, i);
  
          /* skip native interfaces */
          if (interface_opts->if_type != IF_EXTCAP)
          {
              continue;
          }
  
          /* create control pipes if having toolbar */
          if (extcap_has_toolbar(interface_opts->name))
          {
              extcap_create_pipe(interface_opts->name, &interface_opts->extcap_control_in,
                                 EXTCAP_CONTROL_IN_PREFIX);
  #ifdef _WIN32
              interface_opts->extcap_control_in_h = pipe_h;
  #endif
              extcap_create_pipe(interface_opts->name, &interface_opts->extcap_control_out,
                                 EXTCAP_CONTROL_OUT_PREFIX);
  #ifdef _WIN32
              interface_opts->extcap_control_out_h = pipe_h;
  #endif
          }
  
          /* create pipe for fifo */
          if (!extcap_create_pipe(interface_opts->name, &interface_opts->extcap_fifo,
                                  EXTCAP_PIPE_PREFIX))
          {
              return FALSE;
          }
  #ifdef _WIN32
          interface_opts->extcap_pipe_h = pipe_h;
  #endif
  
          /* Create extcap call */
          args = extcap_prepare_arguments(interface_opts);
  
          pipedata = g_new0(ws_pipe_t, 1);
  
          pid = ws_pipe_spawn_async(pipedata, args);
  
          g_ptr_array_foreach(args, ptr_array_free, NULL);
          g_ptr_array_free(args, TRUE);
  
          if (pid == WS_INVALID_PID)
          {
              g_free(pipedata);
              continue;
          }
  
          ws_close(pipedata->stdin_fd);
          interface_opts->extcap_pid = pid;
  
          interface_opts->extcap_child_watch =
              g_child_watch_add(pid, extcap_child_watch_cb, (gpointer)capture_opts);
  
  #ifdef _WIN32
          /* On Windows, wait for extcap to connect to named pipe.
           * Some extcaps will present UAC screen to user.
           * 30 second timeout should be reasonable timeout for extcap to
           * connect to named pipe (including user interaction).
           * Wait on multiple object in case of extcap termination
           * without opening pipe.
           */
          if (pid != WS_INVALID_PID)
          {
              HANDLE pipe_handles[3];
              int num_pipe_handles = 1;
              pipe_handles[0] = interface_opts->extcap_pipe_h;
  
              if (extcap_has_toolbar(interface_opts->name))
              {
                  pipe_handles[1] = interface_opts->extcap_control_in_h;
                  pipe_handles[2] = interface_opts->extcap_control_out_h;
                  num_pipe_handles += 2;
               }
  
              ws_pipe_wait_for_pipe(pipe_handles, num_pipe_handles, pid);
          }
  #endif
  
          interface_opts->extcap_pipedata = (gpointer) pipedata;
      }
  
      return TRUE;
  }
  
  #ifdef _WIN32
  gboolean extcap_create_pipe(const gchar *ifname, gchar **fifo, const gchar *pipe_prefix)
  {
      gchar timestr[ 14 + 1 ];
      time_t current_time;
      gchar *pipename = NULL;
      SECURITY_ATTRIBUTES security;
  
      /* create pipename */
      current_time = time(NULL);
      /*
       * XXX - we trust Windows not to return a time before the Epoch here,
       * so we won't get a null pointer back from localtime().
       */
      strftime(timestr, sizeof(timestr), "%Y%m%d%H%M%S", localtime(&current_time));
      pipename = g_strconcat("\\\\.\\pipe\\", pipe_prefix, "_", ifname, "_", timestr, NULL);
  
      /* Security struct to enable Inheritable HANDLE */
      memset(&security, 0, sizeof(SECURITY_ATTRIBUTES));
      security.nLength = sizeof(SECURITY_ATTRIBUTES);
      security.bInheritHandle = TRUE;
      security.lpSecurityDescriptor = NULL;
  
      /* create a namedPipe */
      pipe_h = CreateNamedPipe(
                   utf_8to16(pipename),
                   PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED,
                   PIPE_TYPE_BYTE | PIPE_READMODE_BYTE | PIPE_WAIT,
                   1, 65536, 65536,
                   300,
                   &security);
  
      if (pipe_h == INVALID_HANDLE_VALUE)
      {
          g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "\nError creating pipe => (%d)", GetLastError());
          g_free (pipename);
          return FALSE;
      }
      else
      {
          g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "\nWireshark Created pipe =>(%s)", pipename);
          *fifo = g_strdup(pipename);
      }
  
      return TRUE;
  }
  #else
  gboolean extcap_create_pipe(const gchar *ifname, gchar **fifo, const gchar *pipe_prefix)
  {
      gchar *temp_name = NULL;
      int fd = 0;
  
      gchar *pfx = g_strconcat(pipe_prefix, "_", ifname, NULL);
      if ((fd = create_tempfile(&temp_name, pfx, NULL)) < 0)
      {
          g_free(pfx);
          return FALSE;
      }
      g_free(pfx);
  
      ws_close(fd);
  
      g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG,
            "Extcap - Creating fifo: %s", temp_name);
  
      if (file_exists(temp_name))
      {
          ws_unlink(temp_name);
      }
  
      if (mkfifo(temp_name, 0600) == 0)
      {
          *fifo = g_strdup(temp_name);
      }
  
      return TRUE;
  }
  #endif
  
  /************* EXTCAP LOAD INTERFACE LIST ***************
   *
   * The following code handles loading and reloading the interface list. It is explicitly
   * kept separate from the rest
   */
  
  
  static void
  extcap_free_interface_info(gpointer data)
  {
      extcap_info *info = (extcap_info *)data;
  
      g_free(info->basename);
      g_free(info->full_path);
      g_free(info->version);
      g_free(info->help);
  
      extcap_free_interfaces(info->interfaces);
  
      g_free(info);
  }
  
  static extcap_info *
  extcap_ensure_interface(const gchar * toolname, gboolean create_if_nonexist)
  {
      extcap_info * element = 0;
  
      if ( prefs.capture_no_extcap )
          return NULL;
  
      if ( ! toolname )
          return element;
  
      if ( ! _loaded_interfaces )
          _loaded_interfaces = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, extcap_free_interface);
  
      element = (extcap_info *) g_hash_table_lookup(_loaded_interfaces, toolname );
      if ( ! element && create_if_nonexist )
      {
          g_hash_table_insert(_loaded_interfaces, g_strdup(toolname), g_new0(extcap_info, 1));
          element = (extcap_info *) g_hash_table_lookup(_loaded_interfaces, toolname );
      }
  
      return element;
  }
  
  extcap_info *
  extcap_get_tool_by_ifname(const gchar *ifname)
  {
      if ( ifname && _tool_for_ifname )
      {
          gchar * toolname = (gchar *)g_hash_table_lookup(_tool_for_ifname, ifname);
          if ( toolname )
              return extcap_ensure_interface(toolname, FALSE);
      }
  
      return NULL;
  }
  
  extcap_info *
  extcap_get_tool_info(const gchar * toolname)
  {
      return extcap_ensure_interface(toolname, FALSE);
  }
  
  static void remove_extcap_entry(gpointer entry, gpointer data _U_)
  {
      extcap_interface *int_iter = (extcap_interface*)entry;
  
      if (int_iter->if_type == EXTCAP_SENTENCE_EXTCAP)
          extcap_free_interface(entry);
  }
  
  static void
  process_new_extcap(const char *extcap, char *output)
  {
      GList * interfaces = NULL, * control_items = NULL, * walker = NULL;
      extcap_interface * int_iter = NULL;
      extcap_info * element = NULL;
      iface_toolbar * toolbar_entry = NULL;
      gchar * toolname = g_path_get_basename(extcap);
  
      GList * interface_keys = g_hash_table_get_keys(_loaded_interfaces);
  
      /* Load interfaces from utility */
      interfaces = extcap_parse_interfaces(output, &control_items);
  
      g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "Loading interface list for %s ", extcap);
  
      /* Seems, that there where no interfaces to be loaded */
      if ( ! interfaces || g_list_length(interfaces) == 0 )
      {
          g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "Cannot load interfaces for %s", extcap );
          g_list_free(interface_keys);
          g_free(toolname);
          return;
      }
  
      /* Load or create the storage element for the tool */
      element = extcap_ensure_interface(toolname, TRUE);
      if ( element == NULL )
      {
          g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_ERROR, "Cannot store interface %s, maybe duplicate?", extcap );
          g_list_foreach(interfaces, remove_extcap_entry, NULL);
          g_list_free(interfaces);
          g_list_free(interface_keys);
          g_free(toolname);
          return;
      }
  
      if (control_items)
      {
          toolbar_entry = g_new0(iface_toolbar, 1);
          toolbar_entry->controls = control_items;
      }
  
      walker = interfaces;
      gchar* help = NULL;
      while (walker != NULL)
      {
          int_iter = (extcap_interface *)walker->data;
  
          if (int_iter->call != NULL)
              g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "Interface found %s\n", int_iter->call);
  
          /* Help is not necessarily stored with the interface, but rather with the version string.
           * As the version string allways comes in front of the interfaces, this ensures, that it get's
           * properly stored with the interface */
          if (int_iter->if_type == EXTCAP_SENTENCE_EXTCAP)
          {
              if (int_iter->call != NULL)
                  g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "  Extcap [%s] ", int_iter->call);
  
              /* Only initialize values if none are set. Need to check only one element here */
              if ( ! element->version )
              {
                  element->version = g_strdup(int_iter->version);
                  element->basename = g_strdup(toolname);
                  element->full_path = g_strdup(extcap);
                  element->help = g_strdup(int_iter->help);
              }
  
              help = int_iter->help;
              if (toolbar_entry)
              {
                  toolbar_entry->menu_title = g_strdup(int_iter->display);
                  toolbar_entry->help = g_strdup(int_iter->help);
              }
  
              walker = g_list_next(walker);
              continue;
          }
  
          /* Only interface definitions will be parsed here. help is already set by the extcap element,
           * which makes it necessary to have version in the list before the interfaces. This is normally
           * the case by design, but could be changed by separating the information in extcap-base. */
          if ( int_iter->if_type == EXTCAP_SENTENCE_INTERFACE )
          {
              if ( g_list_find(interface_keys, int_iter->call) )
              {
                  g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_WARNING, "Extcap interface \"%s\" is already provided by \"%s\" ",
                        int_iter->call, extcap_if_executable(int_iter->call));
                  walker = g_list_next(walker);
                  continue;
              }
  
              if ((int_iter->call != NULL) && (int_iter->display))
                  g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "  Interface [%s] \"%s\" ", int_iter->call, int_iter->display);
  
              int_iter->extcap_path = g_strdup(extcap);
  
              /* Only set the help, if it exists and no parsed help information is present */
              if ( ! int_iter->help && help )
                  int_iter->help = g_strdup(help);
  
              element->interfaces = g_list_append(element->interfaces, int_iter);
              g_hash_table_insert(_tool_for_ifname, g_strdup(int_iter->call), g_strdup(toolname));
  
              if (toolbar_entry)
              {
                  if (!toolbar_entry->menu_title)
                  {
                      toolbar_entry->menu_title = g_strdup(int_iter->display);
                  }
                  toolbar_entry->ifnames = g_list_append(toolbar_entry->ifnames, g_strdup(int_iter->call));
              }
          }
  
          walker = g_list_next(walker);
      }
  
      if (toolbar_entry && toolbar_entry->menu_title)
      {
          iface_toolbar_add(toolbar_entry);
          extcap_iface_toolbar_add(extcap, toolbar_entry);
      }
  
      g_list_foreach(interfaces, remove_extcap_entry, NULL);
      g_list_free(interfaces);
      g_list_free(interface_keys);
      g_free(toolname);
  }
  
  
  /** Thread callback to save the output of a --extcap-config call. */
  static void
  extcap_process_config_cb(thread_pool_t *pool _U_, void *data, char *output)
  {
      extcap_iface_info_t *iface_info = (extcap_iface_info_t *)data;
      iface_info->output = output;
  }
  
  /**
   * Thread callback to process discovered interfaces, scheduling more tasks to
   * retrieve the configuration for each interface. Called once for every extcap
   * program.
   */
  static void
  extcap_process_interfaces_cb(thread_pool_t *pool, void *data, char *output)
  {
      extcap_run_extcaps_info_t *info = (extcap_run_extcaps_info_t *)data;
      guint i = 0;
      guint num_interfaces = 0;
  
      if (!output) {
          // No interfaces available, nothing to do.
          return;
      }
  
      // Save output for process_new_extcap.
      info->output = output;
  
      // Are there any interfaces to query information from?
      GList *interfaces = extcap_parse_interfaces(output, NULL);
      for (GList *iface = interfaces; iface; iface = g_list_next(iface)) {
          extcap_interface *intf = (extcap_interface *)iface->data;
          if (intf->if_type == EXTCAP_SENTENCE_INTERFACE) {
              ++num_interfaces;
          }
      }
      if (num_interfaces == 0) {
          // nothing to do.
          g_list_free_full(interfaces, extcap_free_interface);
          return;
      }
  
      /* GSList is not thread-safe, so pre-allocate an array instead. */
      info->iface_infos = g_new0(extcap_iface_info_t, num_interfaces);
      info->num_interfaces = num_interfaces;
  
      // Schedule new commands to retrieve the configuration.
      for (GList *iface = interfaces; iface; iface = g_list_next(iface)) {
          extcap_interface *intf = (extcap_interface *)iface->data;
          if (intf->if_type != EXTCAP_SENTENCE_INTERFACE) {
              continue;
          }
  
          const char *argv[] = {
              EXTCAP_ARGUMENT_CONFIG,
              EXTCAP_ARGUMENT_INTERFACE,
              intf->call,
              NULL
          };
          extcap_run_task_t *task = g_new0(extcap_run_task_t, 1);
          extcap_iface_info_t *iface_info = &info->iface_infos[i++];
  
          task->extcap_path = info->extcap_path;
          task->argv = g_strdupv((char **)argv);
          task->output_cb = extcap_process_config_cb;
          task->data = iface_info;
          iface_info->ifname = g_strdup(intf->call);
  
          thread_pool_push(pool, task, NULL);
      }
      g_list_free_full(interfaces, extcap_free_interface);
  }
  
  /**
   * Thread callback to check whether the new-style --list-interfaces call with an
   * explicit function succeeded. If not, schedule a call without the new version
   * argument.
   */
  static void
  extcap_list_interfaces_cb(thread_pool_t *pool, void *data, char *output)
  {
      extcap_run_extcaps_info_t *info = (extcap_run_extcaps_info_t *)data;
  
      if (!output) {
          /* No output available, schedule a fallback query. */
          const char *argv[] = {
              EXTCAP_ARGUMENT_LIST_INTERFACES,
              NULL
          };
          extcap_run_task_t *task = g_new0(extcap_run_task_t, 1);
  
          task->extcap_path = info->extcap_path;
          task->argv = g_strdupv((char **)argv);
          task->output_cb = extcap_process_interfaces_cb;
          task->data = info;
  
          thread_pool_push(pool, task, NULL);
      } else {
          extcap_process_interfaces_cb(pool, info, output);
      }
  }
  
  
  /* Handles loading of the interfaces.
   *
   * A list of interfaces can be obtained by calling \ref extcap_loaded_interfaces
   */
  static void
  extcap_load_interface_list(void)
  {
      if (prefs.capture_no_extcap)
          return;
  
      if (_toolbars)
      {
          // Remove existing interface toolbars here instead of in extcap_clear_interfaces()
          // to avoid flicker in shown toolbars when refreshing interfaces.
          GList *toolbar_list = g_hash_table_get_values (_toolbars);
          for (GList *walker = toolbar_list; walker; walker = walker->next)
          {
              iface_toolbar *toolbar = (iface_toolbar *) walker->data;
              iface_toolbar_remove(toolbar->menu_title);
          }
          g_hash_table_remove_all(_toolbars);
      } else {
          _toolbars = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, extcap_free_toolbar);
      }
  
      if (_loaded_interfaces == NULL)
      {
          int major = 0;
          int minor = 0;
          guint count = 0;
          extcap_run_extcaps_info_t *infos;
          GList *unused_arguments = NULL;
  
          _loaded_interfaces = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, extcap_free_interface_info);
          /* Cleanup lookup table */
          if ( _tool_for_ifname )
          {
              g_hash_table_remove_all(_tool_for_ifname);
              _tool_for_ifname = 0;
          } else {
              _tool_for_ifname = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, g_free);
          }
  
          get_ws_version_number(&major, &minor, NULL);
          char *arg_version = g_strdup_printf("%s=%d.%d", EXTCAP_ARGUMENT_VERSION, major, minor);
          const char *argv[] = {
              EXTCAP_ARGUMENT_LIST_INTERFACES,
              arg_version,
              NULL
          };
          infos = (extcap_run_extcaps_info_t *)extcap_run_all(argv,
                  extcap_list_interfaces_cb, sizeof(extcap_run_extcaps_info_t),
                  &count);
          for (guint i = 0; i < count; i++) {
              if (!infos[i].output) {
                  continue;
              }
  
              // Save new extcap and each discovered interface.
              process_new_extcap(infos[i].extcap_path, infos[i].output);
              for (guint j = 0; j < infos[i].num_interfaces; j++) {
                  extcap_iface_info_t *iface_info = &infos[i].iface_infos[j];
  
                  if (!iface_info->output) {
                      continue;
                  }
  
                  extcap_callback_info_t cb_info = {
                      .ifname = iface_info->ifname,
                      .output = iface_info->output,
                      .data = &unused_arguments,
                  };
                  cb_preference(cb_info);
              }
          }
          /* XXX rework cb_preference such that this unused list can be removed. */
          extcap_free_if_configuration(unused_arguments, TRUE);
          extcap_free_extcaps_info_array(infos, count);
          g_free(arg_version);
      }
  }
  
  /*
   * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
   *
   * Local variables:
   * c-basic-offset: 4
   * tab-width: 8
   * indent-tabs-mode: nil
   * End:
   *
   * vi: set shiftwidth=4 tabstop=8 expandtab:
   * :indentSize=4:tabSize=8:noTabs=true:
   */
  