wireshark/extcap.c

/* extcap.h
 *
 * 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
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#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 <glib.h>
#include <log.h>

#include <epan/prefs.h>
#include <epan/prefs-int.h>

#include <wsutil/file_util.h>
#include <wsutil/filesystem.h>
#include <wsutil/tempfile.h>

#include "capture_opts.h"

#ifdef HAVE_EXTCAP

#include "extcap.h"
#include "extcap_parser.h"

#ifdef _WIN32
static HANDLE pipe_h = NULL;
#endif

/* internal container, for all the extcap interfaces that have been found.
 * will be resetted by every call to extcap_interface_list() and is being
 * used in extcap_get_if_* as well as extcap_init_interfaces to ensure,
 * that only extcap interfaces are being given to underlying extcap programs
 */
static GHashTable *ifaces = NULL;

/* internal container, for all the extcap executables that have been found.
 * will be resetted by every call to extcap_interface_list() and is being
 * used for printing information about all extcap interfaces found
 */
static GHashTable *tools = NULL;

/* Callback definition for extcap_foreach */
typedef gboolean (*extcap_cb_t)(const gchar *extcap, const gchar *ifname, gchar *output, void *data,
        gchar **err_str);

/* #define ARG_DEBUG */
#if ARG_DEBUG
static void extcap_debug_arguments ( extcap_arg *arg_iter );
#endif

static gboolean
extcap_if_exists(const gchar *ifname)
{
    if ( !ifname || !ifaces )
        return FALSE;

    if ( g_hash_table_lookup(ifaces, ifname) )
        return TRUE;

    return FALSE;
}

static gboolean
extcap_if_exists_for_extcap(const gchar *ifname, const gchar *extcap)
{
    gchar *entry = (gchar *)g_hash_table_lookup(ifaces, ifname);

    if ( entry && strcmp(entry, extcap) == 0 )
        return TRUE;

    return FALSE;
}

static gchar *
extcap_if_executable(const gchar *ifname)
{
    return (gchar *)g_hash_table_lookup(ifaces, ifname);
}

static void
extcap_if_add(const gchar *ifname, const gchar *extcap)
{
    if ( !g_hash_table_lookup(ifaces, ifname) )
        g_hash_table_insert(ifaces, g_strdup(ifname), g_strdup(extcap));
}

static void
extcap_tool_add(const gchar *extcap, const extcap_interface *interface)
{
    char *toolname;

    if ( !extcap || !interface )
        return;

    toolname = g_path_get_basename(extcap);

    if ( !g_hash_table_lookup(tools, toolname) ) {
        extcap_info * store = (extcap_info *)g_new0(extcap_info, 1);
        store->version = g_strdup(interface->version);
        store->full_path = g_strdup(extcap);
        store->basename = g_strdup(toolname);

        g_hash_table_insert(tools, g_strdup(toolname), store);
    }

    g_free(toolname);
}

/* Note: args does not need to be NULL-terminated. */
static void extcap_foreach(gint argc, gchar **args, extcap_cb_t cb,
        void *cb_data, char **err_str, const char * ifname _U_) {
    const char *dirname = get_extcap_dir();
    GDir *dir;
    const gchar *file;
    gboolean keep_going;
    gint i;
    gchar **argv;
#ifdef _WIN32
    gchar **dll_search_envp;
    gchar *progfile_dir;
#endif

    keep_going = TRUE;

    argv = (gchar **) g_malloc0(sizeof(gchar *) * (argc + 2));

#ifdef _WIN32
    /*
     * Make sure executables can find dependent DLLs and that they're *our*
     * DLLs: https://msdn.microsoft.com/en-us/library/windows/desktop/ms682586.aspx
     * Alternatively we could create a simple wrapper exe similar to Create
     * Hidden Process (http://www.commandline.co.uk/chp/).
     */
    dll_search_envp = g_get_environ();
    progfile_dir = g_strdup_printf("%s;%s", get_progfile_dir(), g_environ_getenv(dll_search_envp, "Path"));
    dll_search_envp = g_environ_setenv(dll_search_envp, "Path", progfile_dir, TRUE);
    g_free(progfile_dir);
#endif

    if ((dir = g_dir_open(dirname, 0, NULL)) != NULL) {
        GString *extcap_path = NULL;

        extcap_path = g_string_new("");
        while (keep_going && (file = g_dir_read_name(dir)) != NULL ) {
            gchar *command_output = NULL;
            gboolean status = FALSE;
            gint exit_status = 0;
            gchar **envp = NULL;

            /* full path to extcap binary */
#ifdef _WIN32
            g_string_printf(extcap_path, "%s\\%s", dirname, file);
            envp = dll_search_envp;
#else
            g_string_printf(extcap_path, "%s/%s", dirname, file);
#endif
            if ( extcap_if_exists(ifname) && !extcap_if_exists_for_extcap(ifname, extcap_path->str ) )
                continue;

#ifdef _WIN32
            argv[0] = g_strescape(extcap_path->str, NULL);
#else
            argv[0] = g_strdup(extcap_path->str);
#endif
            for (i = 0; i < argc; ++i)
                argv[i+1] = args[i];
            argv[argc+1] = NULL;

            status = g_spawn_sync(dirname, argv, envp,
                (GSpawnFlags) 0, NULL, NULL,
                    &command_output, NULL, &exit_status, NULL);

            if (status && exit_status == 0)
            keep_going = cb(extcap_path->str, ifname, command_output, cb_data, err_str);

            g_free(argv[0]);
            g_free(command_output);
        }

        g_dir_close(dir);
        g_string_free(extcap_path, TRUE);
    }

#ifdef _WIN32
    g_strfreev(dll_search_envp);
#endif
    g_free(argv);
}

static gboolean dlt_cb(const gchar *extcap _U_, const gchar *ifname _U_, gchar *output, void *data,
        char **err_str) {
    extcap_token_sentence *tokens;
    extcap_dlt *dlts, *dlt_iter, *next;
    if_capabilities_t *caps;
    GList *linktype_list = NULL;
    data_link_info_t *data_link_info;

    tokens = extcap_tokenize_sentences(output);
    extcap_parse_dlts(tokens, &dlts);

    extcap_free_tokenized_sentence_list(tokens);

    g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "Extcap pipe %s ", extcap);

    /*
     * Allocate the interface capabilities structure.
     */
    caps = (if_capabilities_t *) g_malloc(sizeof *caps);
    caps->can_set_rfmon = FALSE;

    dlt_iter = dlts;
    while (dlt_iter != NULL ) {
        g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG,
                "  DLT %d name=\"%s\" display=\"%s\" ", dlt_iter->number,
                dlt_iter->name, dlt_iter->display);

        data_link_info = g_new(data_link_info_t, 1);
        data_link_info->dlt = dlt_iter->number;
        data_link_info->name = g_strdup(dlt_iter->name);
        data_link_info->description = g_strdup(dlt_iter->display);
        linktype_list = g_list_append(linktype_list, data_link_info);
        dlt_iter = dlt_iter->next_dlt;
    }

    /* Check to see if we built a list */
    if (linktype_list != NULL && data != NULL) {
        caps->data_link_types = linktype_list;
        *(if_capabilities_t **) data = caps;
    } else {
        if (err_str) {
            g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "  returned no DLTs");
            *err_str = g_strdup("Extcap returned no DLTs");
        }
        g_free(caps);
    }

    dlt_iter = dlts;
    while (dlt_iter != NULL ) {
        next = dlt_iter->next_dlt;
        extcap_free_dlt(dlt_iter);
        dlt_iter = next;
    }

    return FALSE;
}

if_capabilities_t *
extcap_get_if_dlts(const gchar *ifname, char **err_str) {
    gchar *argv[3];
    gint i;
    if_capabilities_t *caps = NULL;

    if (err_str != NULL)
        *err_str = NULL;

    if ( extcap_if_exists(ifname) )
    {
        argv[0] = g_strdup(EXTCAP_ARGUMENT_LIST_DLTS);
        argv[1] = g_strdup(EXTCAP_ARGUMENT_INTERFACE);
        argv[2] = g_strdup(ifname);

        extcap_foreach(3, argv, dlt_cb, &caps, err_str, ifname);

        for (i = 0; i < 3; ++i)
            g_free(argv[i]);
    }

    return caps;
}

static gboolean interfaces_cb(const gchar *extcap, const gchar *ifname _U_, gchar *output, void *data,
        char **err_str _U_) {
    GList **il = (GList **) data;
    extcap_token_sentence *tokens;
    extcap_interface *interfaces, *int_iter; /*, *next; */
    if_info_t *if_info;

    tokens = extcap_tokenize_sentences(output);
    extcap_parse_interfaces(tokens, &interfaces);

    extcap_free_tokenized_sentence_list(tokens);

    g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "Extcap pipe %s ", extcap);

    int_iter = interfaces;
    while (int_iter != NULL ) {
        if ( int_iter->if_type == EXTCAP_SENTENCE_INTERFACE && extcap_if_exists(int_iter->call) )
        {
            g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_WARNING, "Extcap interface \"%s\" is already provided by \"%s\" ",
                    int_iter->call, (gchar *)extcap_if_executable(int_iter->call) );
            int_iter = int_iter->next_interface;
            continue;
        }

        if ( int_iter->if_type == EXTCAP_SENTENCE_INTERFACE )
            g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "  Interface [%s] \"%s\" ",
                    int_iter->call, int_iter->display);
        else if ( int_iter->if_type == EXTCAP_SENTENCE_EXTCAP )
            g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "  Extcap [%s] ", int_iter->call);

        if ( int_iter->if_type == EXTCAP_SENTENCE_INTERFACE ) {
            if (il != NULL) {
                if_info = g_new0(if_info_t, 1);
                if_info->name = g_strdup(int_iter->call);
                if_info->friendly_name = g_strdup(int_iter->display);

                if_info->type = IF_EXTCAP;

                if_info->extcap = g_strdup(extcap);
                *il = g_list_append(*il, if_info);
            }

            extcap_if_add(int_iter->call, extcap);
        }

        /* Call for interfaces and tools alike. Multiple calls (because a tool has multiple
         * interfaces) are handled internally */
        extcap_tool_add(extcap, int_iter);

        int_iter = int_iter->next_interface;
    }
    extcap_free_interface(interfaces);

    return TRUE;
}

static gint
if_info_compare(gconstpointer a, gconstpointer b)
{
    gint comp = 0;
    if_info_t * if_a = (if_info_t *)a;
    if_info_t * if_b = (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;
}

GHashTable *
extcap_tools_list(void) {
    if ( tools == NULL || g_hash_table_size(tools) == 0 )
        extcap_interface_list(NULL, NULL);

    return tools;
}

static void
extcap_free_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);
}

void
extcap_interface_list(GList **listp, char **err_str) {
    gchar *argv;
    /* gint i; */
    GList *ret = NULL;
    GList *entry;
    void *data;

    if (err_str != NULL)
        *err_str = NULL;

    /* ifaces is used as cache, do not destroy its contents when
     * returning or no extcap interfaces can be queried for options */
    if (ifaces == NULL)
        ifaces = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, g_free);
    else
        g_hash_table_remove_all(ifaces);

    if (tools == NULL)
        tools = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, extcap_free_info);
    else
        g_hash_table_remove_all(tools);

    argv = g_strdup(EXTCAP_ARGUMENT_LIST_INTERFACES);

    extcap_foreach(1, &argv, interfaces_cb, (listp != NULL) ? &ret : NULL, err_str, NULL);

    g_free(argv);

    if (listp != NULL) {
        /* Sort the list */
        ret = g_list_sort(ret, if_info_compare);

        /* Append the interfaces to the list. */
        while (ret != NULL) {
            entry = g_list_first(ret);
            data = entry->data;
            ret = g_list_delete_link(ret, entry);
            *listp = g_list_append(*listp, data);
        }
    }
}

static void extcap_free_arg_elem(gpointer data, gpointer user_data _U_) {
    extcap_free_arg((extcap_arg *) data);
    g_free(data);
}

void extcap_register_preferences(void)
{
    GList * interfaces = NULL;

    module_t * dev_module = prefs_find_module("extcap");

    if ( !dev_module )
        return;

    if ( ! ifaces || g_hash_table_size(ifaces) == 0 )
        extcap_interface_list(NULL, NULL);

    interfaces = g_hash_table_get_keys(ifaces);

    while ( interfaces ) {
        extcap_get_if_configuration((gchar *)interfaces->data);

        interfaces = g_list_next(interfaces);
    }
}

static void extcap_free_if_configuration(GList *list)
{
    GList *elem, *sl;

    for (elem = g_list_first(list); elem; elem = elem->next)
    {
        if (elem->data != NULL) {
            /* g_list_free_full() only exists since 2.28. */
            sl = g_list_first((GList *)elem->data);
            g_list_foreach(sl, (GFunc)extcap_free_arg_elem, NULL);
            g_list_free(sl);
        }
    }
    g_list_free(list);
}

gchar * extcap_settings_key(const gchar * ifname, const gchar * setting)
{
    gchar * setting_nohyphen;
    gchar * ifname_underscore;
    gchar * ifname_lower;
    gchar * key;
    GRegex * regex = g_regex_new ("(?![a-zA-Z1-9_]).", (GRegexCompileFlags) 0, (GRegexMatchFlags) 0, NULL );

    if (!regex)
        return NULL;

    setting_nohyphen =
        g_regex_replace_literal(regex, setting, strlen(setting), 0,
            "", (GRegexMatchFlags) 0, NULL );
    ifname_underscore =
        g_regex_replace_literal(regex, ifname, strlen(ifname), 0,
            "_", (GRegexMatchFlags) 0, NULL );
    ifname_lower = g_utf8_strdown(ifname_underscore, -1);
    key = g_strconcat(ifname_lower, ".", setting_nohyphen, NULL);

    g_free(setting_nohyphen);
    g_free(ifname_underscore);
    g_free(ifname_lower);
    g_regex_unref(regex);

    return key;
}

static gboolean search_cb(const gchar *extcap _U_, const gchar *ifname _U_, gchar *output, void *data,
        char **err_str _U_) {
    extcap_token_sentence *tokens = NULL;
    GList *arguments = NULL;
    GList **il = (GList **) data;
    module_t * dev_module = NULL;

    tokens = extcap_tokenize_sentences(output);
    arguments = extcap_parse_args(tokens);

    extcap_free_tokenized_sentence_list(tokens);

#if ARG_DEBUG
    extcap_debug_arguments ( arguments );
#endif

    dev_module = prefs_find_module("extcap");

    if ( dev_module ) {
        GList * walker = arguments;

        while ( walker != NULL ) {
            extcap_arg * arg = (extcap_arg *)walker->data;

            if ( arg->save ) {
                struct preference * pref = NULL;
                gchar * pref_ifname = extcap_settings_key(ifname, arg->call);

                if ( ( pref = prefs_find_preference(dev_module, pref_ifname) ) == NULL ) {
                    /* Set an initial value */
                    if ( ! arg->storeval && arg->default_complex )
                        arg->storeval = g_strdup(arg->default_complex->_val);

                    prefs_register_string_preference(dev_module, g_strdup(pref_ifname),
                            arg->display, arg->display, (const gchar **)&(arg->storeval));
                } else {
                    /* Been here before, restore stored value */
                    if (! arg->storeval && pref->varp.string)
                        arg->storeval = g_strdup(*(pref->varp.string));
                    }
                g_free(pref_ifname);
            }

            walker = g_list_next(walker);
        }
    }

    *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) {
    gchar *argv[3];
    GList *ret = NULL;
    gchar **err_str = NULL;
    int i;

    if ( extcap_if_exists(ifname) )
    {
        g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "Extcap path %s",
                get_extcap_dir());

        argv[0] = g_strdup(EXTCAP_ARGUMENT_CONFIG);
        argv[1] = g_strdup(EXTCAP_ARGUMENT_INTERFACE);
        argv[2] = g_strdup(ifname);

        extcap_foreach(3, argv, search_cb, &ret, err_str, ifname);

        for (i = 0; i < 3; i++)
            g_free(argv[i]);
    }

    return ret;
}

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((const char *)( 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 ) {
                    gchar * stored = NULL;
                    gchar * defval = NULL;

                    if ( arg->storeval != NULL )
                        stored = arg->storeval;

                    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 || strlen(g_strchomp(stored)) <= (size_t)0) )
                            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);

    return found;
}

void extcap_cleanup(capture_options * capture_opts) {
    interface_options interface_opts;
    guint icnt = 0;

    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;

        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 (pipe_h)
        {
            g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG,
                "Extcap [%s] - Closing pipe", interface_opts.name);
            FlushFileBuffers(pipe_h);
            DisconnectNamedPipe(pipe_h);
            CloseHandle(pipe_h);
        }
#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;
        }
#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);

        if (interface_opts.extcap_pid != INVALID_EXTCAP_PID)
        {
#ifdef _WIN32
            TerminateProcess(interface_opts.extcap_pid, 0);
#endif
            g_spawn_close_pid(interface_opts.extcap_pid);
            interface_opts.extcap_pid = INVALID_EXTCAP_PID;
        }

        /* Make sure modified interface_opts is saved in capture_opts. */
        capture_opts->ifaces = g_array_remove_index(capture_opts->ifaces, icnt);
        g_array_insert_val(capture_opts->ifaces, icnt, interface_opts);
    }
}

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;
}

static void extcap_child_watch_cb(GPid pid, gint status _U_, gpointer user_data)
{
    guint i;
    interface_options interface_opts;
    capture_options *capture_opts = (capture_options *)user_data;

    /* 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)
        {
            interface_opts.extcap_pid = INVALID_EXTCAP_PID;
            g_source_remove(interface_opts.extcap_child_watch);
            interface_opts.extcap_child_watch = 0;

            capture_opts->ifaces = g_array_remove_index(capture_opts->ifaces, i);
            g_array_insert_val(capture_opts->ifaces, i, interface_opts);
            break;
        }
    }
}

/* 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;

    for (i = 0; i < capture_opts->ifaces->len; i++)
    {
        GPtrArray *args = NULL;
        GPid pid = INVALID_EXTCAP_PID;
        gchar **tmp;
        int tmp_i;

        interface_opts = g_array_index(capture_opts->ifaces, interface_options, i);

        /* skip native interfaces */
        if (interface_opts.if_type != IF_EXTCAP )
            continue;

        /* create pipe for fifo */
        if ( ! extcap_create_pipe ( &interface_opts.extcap_fifo ) )
            return FALSE;

        /* Create extcap call */
        args = g_ptr_array_new();
#define add_arg(X) g_ptr_array_add(args, 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_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) {
                    gchar * stored = NULL, * defval = NULL;
                    /* In case of boolflags only first element in arg_list is relevant. */
                    arg_iter = (extcap_arg*) (arg_list->data);
                    if ( arg_iter->storeval != NULL )
                        stored = arg_iter->storeval;

                    if ( arg_iter->default_complex != NULL && arg_iter->default_complex->_val != NULL )
                        defval = arg_iter->default_complex->_val;

                    /* Different data in storage then set for default */
                    if ( g_strcmp0(stored, defval) != 0 ) {
                        if ( arg_iter->arg_type == EXTCAP_ARG_BOOLFLAG ) {
                            if ( g_strcmp0(stored, "true") == 0 )
                                add_arg(arg_iter->call);
                        } else {
                            gchar * call = g_strconcat(arg_iter->call, " ", stored, NULL);
                            add_arg(call);
                            g_free(call);
                        }
                    } else if  (arg_iter->arg_type == EXTCAP_ARG_BOOLFLAG) {
                        if (extcap_complex_get_bool(arg_iter->default_complex))
                            add_arg(arg_iter->call);
                    }

                    arg_list = arg_list->next;
                }
            }

            extcap_free_if_configuration(arglist);
        }
        else
        {
            g_hash_table_foreach_remove(interface_opts.extcap_args, extcap_add_arg_and_remove_cb, args);
        }
        add_arg(NULL);
#undef add_arg

        /* Dump commandline parameters sent to extcap. */
        for (tmp = (gchar **)args->pdata, tmp_i = 0; *tmp && **tmp; ++tmp_i, ++tmp)
        {
            g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "argv[%d]: %s", tmp_i, *tmp);
        }

        /* Wireshark for windows crashes here sometimes *
         * Access violation reading location 0x...      */
        g_spawn_async(NULL, (gchar **)args->pdata, NULL,
                    (GSpawnFlags) G_SPAWN_DO_NOT_REAP_CHILD, NULL, NULL,
                    &pid,NULL);

        g_ptr_array_foreach(args, (GFunc)g_free, NULL);
        g_ptr_array_free(args, TRUE);
        interface_opts.extcap_pid = pid;
        interface_opts.extcap_child_watch =
            g_child_watch_add(pid, extcap_child_watch_cb, (gpointer)capture_opts);
        capture_opts->ifaces = g_array_remove_index(capture_opts->ifaces, i);
        g_array_insert_val(capture_opts->ifaces, i, interface_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.
         *
         * Minimum supported version of Windows: XP / Server 2003.
         */
        if (pid != INVALID_EXTCAP_PID)
        {
            DWORD dw;
            HANDLE handles[2];
            OVERLAPPED ov;
            ov.Pointer = 0;
            ov.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);

            ConnectNamedPipe(pipe_h, &ov);
            handles[0] = ov.hEvent;
            handles[1] = pid;

            if (GetLastError() == ERROR_PIPE_CONNECTED)
            {
                g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "extcap connected to pipe");
            }
            else
            {
                dw = WaitForMultipleObjects(2, handles, FALSE, 30000);
                if (dw == WAIT_OBJECT_0)
                {
                    /* ConnectNamedPipe finished. */
                    DWORD code;

                    code = GetLastError();
                    if (code == ERROR_IO_PENDING)
                    {
                        DWORD dummy;
                        if (!GetOverlappedResult(ov.hEvent, &ov, &dummy, TRUE))
                        {
                            code = GetLastError();
                        }
                        else
                        {
                            code = ERROR_SUCCESS;
                        }
                    }

                    g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "ConnectNamedPipe code: %d", code);
                }
                else if (dw == (WAIT_OBJECT_0 + 1))
                {
                    /* extcap process terminated. */
                    g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "extcap terminated without connecting to pipe!");
                }
                else if (dw == WAIT_TIMEOUT)
                {
                    g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "extcap didn't connect to pipe within 30 seconds!");
                }
                else
                {
                    g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG, "WaitForMultipleObjects returned 0x%08X. Error %d", dw, GetLastError());
                }
            }

            CloseHandle(ov.hEvent);
        }
#endif
    }

    return TRUE;
}

#ifdef _WIN32
/* called by capture_sync to get the CreatNamedPipe handle*/
HANDLE
extcap_get_win32_handle()
{
    return pipe_h;
}
#endif

gboolean extcap_create_pipe(char ** fifo)
{
#ifdef _WIN32
    gchar timestr[ 14+1 ];
    time_t current_time;

    gchar *pipename = NULL;

    SECURITY_ATTRIBUTES security;
    /* create pipename */
    current_time = time(NULL);
    strftime(timestr, sizeof(timestr), "%Y%m%d%H%M%S", localtime(&current_time));
    pipename = g_strconcat ( "\\\\.\\pipe\\", EXTCAP_PIPE_PREFIX, "_", 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_MESSAGE| PIPE_READMODE_MESSAGE | PIPE_WAIT,
                5, 65536, 65536,
                300,
                &security);

    if (pipe_h == INVALID_HANDLE_VALUE)
    {
        g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG,"\nError creating pipe => (%d)", GetLastError());
        return FALSE;
    }
    else
    {
        g_log(LOG_DOMAIN_CAPTURE, G_LOG_LEVEL_DEBUG,"\nWireshark Created pipe =>(%s)",pipename);
        *fifo = g_strdup(pipename);
    }
#else
    gchar *temp_name = NULL;
    int fd = 0;

    if ((fd = create_tempfile(&temp_name, EXTCAP_PIPE_PREFIX)) < 0 )
        return FALSE;

    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);
#endif

    return TRUE;
}

#if ARG_DEBUG
void extcap_debug_arguments ( extcap_arg *arg_iter )
{
    extcap_value *v = NULL;
    GList *walker = NULL;

    printf("debug - parser dump\n");
    while (arg_iter != NULL) {
        printf("ARG %d call=%s display=\"%s\" type=", arg_iter->arg_num, arg_iter->call, arg_iter->display);

        switch (arg_iter->arg_type) {
            case EXTCAP_ARG_INTEGER:
            printf("int\n");
            break;
            case EXTCAP_ARG_UNSIGNED:
            printf("unsigned\n");
            break;
            case EXTCAP_ARG_LONG:
            printf("long\n");
            break;
            case EXTCAP_ARG_DOUBLE:
            printf("double\n");
            break;
            case EXTCAP_ARG_BOOLEAN:
            printf("boolean\n");
            break;
            case EXTCAP_ARG_MENU:
            printf("menu\n");
            break;
            case EXTCAP_ARG_RADIO:
            printf("radio\n");
            break;
            case EXTCAP_ARG_SELECTOR:
            printf("selctor\n");
            break;
            case EXTCAP_ARG_STRING:
            printf ( "string\n" );
            break;
            case EXTCAP_ARG_PASSWORD:
            printf ( "PASSWORD\n" );
            break;
            case EXTCAP_ARG_MULTICHECK:
            printf ( "unknown\n" );
            break;
            case EXTCAP_ARG_UNKNOWN:
            printf ( "unknown\n" );
            break;
        }

        if (arg_iter->range_start != NULL && arg_iter->range_end != NULL) {
            printf("\tRange: ");
            extcap_printf_complex(arg_iter->range_start);
            printf(" - ");
            extcap_printf_complex(arg_iter->range_end);
            printf("\n");
        }

        for ( walker = g_list_first ( arg_iter->value_list ); walker; walker = walker->next )
        {
            v = (extcap_value *)walker->data;
            if (v->is_default)
            printf("*");
            printf("\tcall=\"%p\" display=\"%p\"\n", v->call, v->display);
            printf("\tcall=\"%s\" display=\"%s\"\n", v->call, v->display);
        }

        arg_iter = arg_iter->next_arg;
    }
}
#endif
#endif

/*
 * 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:
 */