path: root/ui/capture.c

/* capture.c
 * Routines for packet capture
 *
 * 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"
#define WS_LOG_DOMAIN LOG_DOMAIN_CAPTURE

#ifdef HAVE_LIBPCAP

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

#include <glib.h>

#include <epan/packet.h>
#include <epan/dfilter/dfilter.h>
#include "extcap.h"
#include "file.h"
#include "ui/capture.h"
#include "capture/capture_ifinfo.h"
#include <capture/capture_sync.h>
#include "ui/capture_info.h"
#include "ui/capture_ui_utils.h"
#include "ui/util.h"
#include "ui/urls.h"
#include "capture/capture-pcap-util.h"

#ifdef _WIN32
#include "capture/capture-wpcap.h"
#endif

#include "ui/simple_dialog.h"
#include "ui/ws_ui_util.h"

#include "wsutil/file_util.h"
#include "wsutil/str_util.h"
#include <wsutil/filesystem.h>
#include <wsutil/wslog.h>
#include <wsutil/ws_assert.h>

typedef struct if_stat_cache_item_s {
    char *name;
    struct pcap_stat ps;
} if_stat_cache_item_t;

struct if_stat_cache_s {
    int stat_fd;
    ws_process_id fork_child;
    GList *cache_list;  /* List of if_stat_chache_entry_t */
};

/* this callback mechanism should possibly be replaced by the g_signal_...() stuff (if I only would know how :-) */
typedef struct {
    capture_callback_t cb_fct;
    gpointer user_data;
} capture_callback_data_t;

static GList *capture_callbacks = NULL;

static void
capture_callback_invoke(int event, capture_session *cap_session)
{
    capture_callback_data_t *cb;
    GList *cb_item = capture_callbacks;

    /* there should be at least one interested */
    ws_assert(cb_item != NULL);

    while(cb_item != NULL) {
        cb = (capture_callback_data_t *)cb_item->data;
        cb->cb_fct(event, cap_session, cb->user_data);
        cb_item = g_list_next(cb_item);
    }
}


void
capture_callback_add(capture_callback_t func, gpointer user_data)
{
    capture_callback_data_t *cb;

    cb = g_new(capture_callback_data_t, 1);
    cb->cb_fct = func;
    cb->user_data = user_data;

    capture_callbacks = g_list_prepend(capture_callbacks, cb);
}

void
capture_callback_remove(capture_callback_t func, gpointer user_data)
{
    capture_callback_data_t *cb;
    GList *cb_item = capture_callbacks;

    while(cb_item != NULL) {
        cb = (capture_callback_data_t *)cb_item->data;
        if(cb->cb_fct == func && cb->user_data == user_data) {
            capture_callbacks = g_list_remove(capture_callbacks, cb);
            g_free(cb);
            return;
        }
        cb_item = g_list_next(cb_item);
    }

    ws_assert_not_reached();
}

/**
 * Start a capture.
 *
 * @return TRUE if the capture starts successfully, FALSE otherwise.
 */
gboolean
capture_start(capture_options *capture_opts, GPtrArray *capture_comments,
              capture_session *cap_session, info_data_t* cap_data,
              void(*update_cb)(void))
{
    GString *source;

    cap_session->state = CAPTURE_PREPARING;
    cap_session->count = 0;
    ws_message("Capture Start ...");
    source = get_iface_list_string(capture_opts, IFLIST_SHOW_FILTER);
    cf_set_tempfile_source((capture_file *)cap_session->cf, source->str);
    g_string_free(source, TRUE);
    /* try to start the capture child process */
    if (!sync_pipe_start(capture_opts, capture_comments, cap_session,
                         cap_data, update_cb)) {
        /* We failed to start the capture child. */
        if(capture_opts->save_file != NULL) {
            g_free(capture_opts->save_file);
            capture_opts->save_file = NULL;
        }

        ws_message("Capture Start failed.");
        cap_session->state = CAPTURE_STOPPED;
        return FALSE;
    }

    // Do we need data structures for ignoring duplicate frames?
    if (prefs.ignore_dup_frames && capture_opts->real_time_mode) {
        fifo_string_cache_init(&cap_session->frame_dup_cache,
                prefs.ignore_dup_frames_cache_entries, g_free);
        cap_session->frame_cksum = g_checksum_new(G_CHECKSUM_SHA256);
    }

    /* the capture child might not respond shortly after bringing it up */
    /* (for example: it will block if no input arrives from an input capture pipe (e.g. mkfifo)) */

    /* to prevent problems, bring the main GUI into "capture mode" right after a successful */
    /* spawn/exec of the capture child, without waiting for any response from it */
    capture_callback_invoke(capture_cb_capture_prepared, cap_session);

    wtap_rec_init(&cap_session->rec);
    ws_buffer_init(&cap_session->buf, 1514);

    cap_session->wtap = NULL;

    if (capture_opts->show_info) {
        if (cap_data->counts.counts_hash != NULL)
        {
            /* Clean up any previous lists of packet counts */
            g_hash_table_destroy(cap_data->counts.counts_hash);
        }

        cap_data->counts.counts_hash = g_hash_table_new_full(g_direct_hash, g_direct_equal, NULL, g_free);
        cap_data->counts.other = 0;
        cap_data->counts.total = 0;

        cap_data->ui.counts = &cap_data->counts;

        capture_info_ui_create(&cap_data->ui, cap_session);
    }

    return TRUE;
}


void
capture_stop(capture_session *cap_session)
{
    ws_message("Capture Stop ...");

    capture_callback_invoke(capture_cb_capture_stopping, cap_session);

    if (!extcap_session_stop(cap_session)) {
        extcap_request_stop(cap_session);
        cap_session->capture_opts->stop_after_extcaps = TRUE;
    } else {
        /* stop the capture child gracefully */
        sync_pipe_stop(cap_session);
    }
}


void
capture_kill_child(capture_session *cap_session)
{
    ws_info("Capture Kill");

    /* kill the capture child */
    sync_pipe_kill(cap_session->fork_child);
}

/* We've succeeded in doing a (non real-time) capture; try to read it into a new capture file */
static gboolean
capture_input_read_all(capture_session *cap_session, gboolean is_tempfile,
                       gboolean drops_known, guint32 drops)
{
    capture_options *capture_opts = cap_session->capture_opts;
    int err;

    /* Capture succeeded; attempt to open the capture file. */
    if (cf_open((capture_file *)cap_session->cf, capture_opts->save_file, WTAP_TYPE_AUTO, is_tempfile, &err) != CF_OK) {
        /* We're not doing a capture any more, so we don't have a save file. */
        return FALSE;
    }

    /* Set the read filter to NULL. */
    /* XXX - this is odd here; try to put it somewhere where it fits better */
    cf_set_rfcode((capture_file *)cap_session->cf, NULL);

    /* Get the packet-drop statistics.

       XXX - there are currently no packet-drop statistics stored
       in libpcap captures, and that's what we're reading.

       At some point, we will add support in Wiretap to return
       packet-drop statistics for capture file formats that store it,
       and will make "cf_read()" get those statistics from Wiretap.
       We clear the statistics (marking them as "not known") in
       "cf_open()", and "cf_read()" will only fetch them and mark
       them as known if Wiretap supplies them, so if we get the
       statistics now, after calling "cf_open()" but before calling
       "cf_read()", the values we store will be used by "cf_read()".

       If a future libpcap capture file format stores the statistics,
       we'll put them into the capture file that we write, and will
       thus not have to set them here - "cf_read()" will get them from
       the file and use them. */
    if (drops_known) {
        cf_set_drops_known((capture_file *)cap_session->cf, TRUE);

        /* XXX - on some systems, libpcap doesn't bother filling in
           "ps_ifdrop" - it doesn't even set it to zero - so we don't
           bother looking at it.

           Ideally, libpcap would have an interface that gave us
           several statistics - perhaps including various interface
           error statistics - and would tell us which of them it
           supplies, allowing us to display only the ones it does. */
        cf_set_drops((capture_file *)cap_session->cf, drops);
    }

    /* read in the packet data */
    switch (cf_read((capture_file *)cap_session->cf, /*reloading=*/FALSE)) {

        case CF_READ_OK:
        case CF_READ_ERROR:
            /* Just because we got an error, that doesn't mean we were unable
               to read any of the file; we handle what we could get from the
               file. */
            break;

        case CF_READ_ABORTED:
            /* User wants to quit program. Exit by leaving the main loop,
               so that any quit functions we registered get called. */
            exit_application(0);
            return FALSE;
    }

    /* if we didn't capture even a single packet, close the file again */
    if(cap_session->count == 0 && !capture_opts->restart) {
        simple_dialog(ESD_TYPE_INFO, ESD_BTN_OK,
                "%sNo packets captured.%s\n"
                "\n"
                "As no data was captured, closing the %scapture file.\n"
                "\n"
                "\n"
                "Help about capturing can be found at\n"
                "\n"
                "       " WS_WIKI_URL("CaptureSetup")
#ifdef _WIN32
                "\n\n"
                "Wireless (Wi-Fi/WLAN):\n"
                "Try to switch off promiscuous mode in the Capture Options"
#endif
                "",
                simple_dialog_primary_start(), simple_dialog_primary_end(),
                (cf_is_tempfile((capture_file *)cap_session->cf)) ? "temporary " : "");
        cf_close((capture_file *)cap_session->cf);
    }
    return TRUE;
}

static const char *
cf_open_error_message(int err, gchar *err_info)
{
    const char *errmsg;
    static char errmsg_errno[1024 + 1];

    if (err < 0) {
        /* Wiretap error. */
        switch (err) {

        case WTAP_ERR_NOT_REGULAR_FILE:
            errmsg = "The file \"%s\" is a \"special file\" or socket or other non-regular file.";
            break;

        case WTAP_ERR_FILE_UNKNOWN_FORMAT:
            /* Seen only when opening a capture file for reading. */
            errmsg = "The file \"%s\" isn't a capture file in a format Wireshark understands.";
            break;

        case WTAP_ERR_UNSUPPORTED:
            snprintf(errmsg_errno, sizeof(errmsg_errno),
                       "The file \"%%s\" contains record data that Wireshark doesn't support.\n"
                       "(%s)", err_info != NULL ? err_info : "no information supplied");
            g_free(err_info);
            errmsg = errmsg_errno;
            break;

        case WTAP_ERR_ENCAP_PER_PACKET_UNSUPPORTED:
            errmsg = "The file \"%s\" is a capture for a network type that Wireshark doesn't support.";
            break;

        case WTAP_ERR_BAD_FILE:
            snprintf(errmsg_errno, sizeof(errmsg_errno),
                       "The file \"%%s\" appears to be damaged or corrupt.\n"
                       "(%s)", err_info != NULL ? err_info : "no information supplied");
            g_free(err_info);
            errmsg = errmsg_errno;
            break;

        case WTAP_ERR_CANT_OPEN:
            errmsg = "The file \"%s\" could not be opened for some unknown reason.";
            break;

        case WTAP_ERR_SHORT_READ:
            errmsg = "The file \"%s\" appears to have been cut short"
                " in the middle of a packet or other data.";
            break;

        case WTAP_ERR_DECOMPRESS:
            snprintf(errmsg_errno, sizeof(errmsg_errno),
                       "The file \"%%s\" cannot be decompressed; it may be damaged or corrupt.\n"
                       "(%s)", err_info != NULL ? err_info : "no information supplied");
            g_free(err_info);
            errmsg = errmsg_errno;
            break;

        case WTAP_ERR_INTERNAL:
            snprintf(errmsg_errno, sizeof(errmsg_errno),
                       "An internal error occurred opening the file \"%%s\".\n"
                       "(%s)", err_info != NULL ? err_info : "no information supplied");
            g_free(err_info);
            errmsg = errmsg_errno;
            break;

        case WTAP_ERR_DECOMPRESSION_NOT_SUPPORTED:
            snprintf(errmsg_errno, sizeof(errmsg_errno),
                       "The file \"%%s\" cannot be decompressed; it is compressed in a way that We don't support.\n"
                       "(%s)", err_info != NULL ? err_info : "no information supplied");
            g_free(err_info);
            errmsg = errmsg_errno;
            break;

        default:
            snprintf(errmsg_errno, sizeof(errmsg_errno),
                       "The file \"%%s\" could not be opened: %s.",
                       wtap_strerror(err));
            errmsg = errmsg_errno;
            break;
        }
    }
    else
        errmsg = file_open_error_message(err, FALSE);
    return errmsg;
}

/* capture child tells us we have a new (or the first) capture file */
static bool
capture_input_new_file(capture_session *cap_session, gchar *new_file)
{
    capture_options *capture_opts = cap_session->capture_opts;
    gboolean is_tempfile;
    int  err;
    gchar *err_info;
    gchar *err_msg;

    if(cap_session->state == CAPTURE_PREPARING) {
        ws_message("Capture started");
    }
    ws_message("File: \"%s\"", new_file);

    ws_assert(cap_session->state == CAPTURE_PREPARING || cap_session->state == CAPTURE_RUNNING);

    /* free the old filename */
    if(capture_opts->save_file != NULL) {
        /* we start a new capture file, close the old one (if we had one before). */
        /* (we can only have an open capture file in real_time_mode!) */
        if (((capture_file*)cap_session->cf)->state == FILE_READ_PENDING) {
            capture_callback_invoke(capture_cb_capture_fixed_finished, cap_session);
        } else if (((capture_file*)cap_session->cf)->state != FILE_CLOSED) {
            cap_session->session_will_restart = TRUE;
            capture_callback_invoke(capture_cb_capture_update_finished, cap_session);
            cf_finish_tail((capture_file *)cap_session->cf,
                           &cap_session->rec, &cap_session->buf, &err,
                           &cap_session->frame_dup_cache, cap_session->frame_cksum);
            cf_close((capture_file *)cap_session->cf);
        }
        g_free(capture_opts->save_file);
        is_tempfile = FALSE;
        cf_set_tempfile((capture_file *)cap_session->cf, FALSE);
    } else {
        /* we didn't have a save_file before; must be a tempfile */
        is_tempfile = TRUE;
        cf_set_tempfile((capture_file *)cap_session->cf, TRUE);
    }

    /* save the new filename */
    capture_opts->save_file = g_strdup(new_file);

    /* if we are in real-time mode, open the new file now */
    if(capture_opts->real_time_mode) {
        /* Attempt to open the capture file and set up to read from it. */
        switch(cf_open((capture_file *)cap_session->cf, capture_opts->save_file, WTAP_TYPE_AUTO, is_tempfile, &err)) {
            case CF_OK:
                break;
            case CF_ERROR:
                /* Don't unlink (delete) the save file - leave it around,
                   for debugging purposes. */
                g_free(capture_opts->save_file);
                capture_opts->save_file = NULL;
                return FALSE;
        }
    } else {
        capture_callback_invoke(capture_cb_capture_prepared, cap_session);
    }

    if(capture_opts->show_info) {
        if (cap_session->wtap != NULL) {
            wtap_close(cap_session->wtap);
        }

        cap_session->wtap = wtap_open_offline(new_file, WTAP_TYPE_AUTO, &err, &err_info, FALSE);
        if (!cap_session->wtap) {
            err_msg = ws_strdup_printf(cf_open_error_message(err, err_info),
                                      new_file);
            ws_warning("capture_input_new_file: %d (%s)", err, err_msg);
            g_free(err_msg);
            return FALSE;
        }
    }

    if(capture_opts->real_time_mode) {
        capture_callback_invoke(capture_cb_capture_update_started, cap_session);
    } else {
        capture_callback_invoke(capture_cb_capture_fixed_started, cap_session);
    }
    cap_session->state = CAPTURE_RUNNING;

    return TRUE;
}

static void
capture_info_packet(info_data_t* cap_info, gint wtap_linktype, const guchar *pd, guint32 caplen, union wtap_pseudo_header *pseudo_header)
{
    capture_packet_info_t cpinfo;

    /* Setup the capture packet structure */
    cpinfo.counts = cap_info->counts.counts_hash;

    cap_info->counts.total++;
    if (!try_capture_dissector("wtap_encap", wtap_linktype, pd, 0, caplen, &cpinfo, pseudo_header))
        cap_info->counts.other++;
}

/* new packets arrived */
static void
capture_info_new_packets(int to_read, wtap *wth, info_data_t* cap_info)
{
    int err;
    gchar *err_info;
    gint64 data_offset;
    wtap_rec rec;
    Buffer buf;
    union wtap_pseudo_header *pseudo_header;
    int wtap_linktype;

    cap_info->ui.new_packets = to_read;

    /*ws_warning("new packets: %u", to_read);*/

    wtap_rec_init(&rec);
    ws_buffer_init(&buf, 1514);
    while (to_read > 0) {
        wtap_cleareof(wth);
        if (wtap_read(wth, &rec, &buf, &err, &err_info, &data_offset)) {
            if (rec.rec_type == REC_TYPE_PACKET) {
                pseudo_header = &rec.rec_header.packet_header.pseudo_header;
                wtap_linktype = rec.rec_header.packet_header.pkt_encap;

                capture_info_packet(cap_info, wtap_linktype,
                    ws_buffer_start_ptr(&buf),
                    rec.rec_header.packet_header.caplen,
                    pseudo_header);

                /*ws_warning("new packet");*/
                to_read--;
            }
            wtap_rec_reset(&rec);
        }
    }
    wtap_rec_cleanup(&rec);
    ws_buffer_free(&buf);

    capture_info_ui_update(&cap_info->ui);
}

/* capture child tells us we have new packets to read */
static void
capture_input_new_packets(capture_session *cap_session, int to_read)
{
    capture_options *capture_opts = cap_session->capture_opts;
    int  err;

    ws_assert(capture_opts->save_file);

    if(capture_opts->real_time_mode) {
        if (((capture_file*)cap_session->cf)->state == FILE_READ_PENDING) {
            /* Attempt to open the capture file and set up to read from it. */
            switch (cf_open((capture_file*)cap_session->cf, capture_opts->save_file, WTAP_TYPE_AUTO, cf_is_tempfile((capture_file*)cap_session->cf), &err)) {
            case CF_OK:
                break;
            case CF_ERROR:
                /* Don't unlink (delete) the save file - leave it around,
                   for debugging purposes. */
                g_free(capture_opts->save_file);
                capture_opts->save_file = NULL;
                capture_kill_child(cap_session);
            }
            capture_callback_invoke(capture_cb_capture_update_started, cap_session);
        }
        /* Read from the capture file the number of records the child told us it added. */
        to_read += cap_session->count_pending;
        cap_session->count_pending = 0;
        switch (cf_continue_tail((capture_file *)cap_session->cf, to_read,
                                 &cap_session->rec, &cap_session->buf, &err,
                                 &cap_session->frame_dup_cache, cap_session->frame_cksum)) {

            case CF_READ_OK:
            case CF_READ_ERROR:
                /* Just because we got an error, that doesn't mean we were unable
                   to read any of the file; we handle what we could get from the
                   file.

                   XXX - abort on a read error? */
                capture_callback_invoke(capture_cb_capture_update_continue, cap_session);
                break;

            case CF_READ_ABORTED:
                /* Kill the child capture process; the user wants to exit, and we
                   shouldn't just leave it running. */
                capture_kill_child(cap_session);
                break;
        }
    } else {
        cf_fake_continue_tail((capture_file *)cap_session->cf);
        cap_session->count_pending += to_read;

        capture_callback_invoke(capture_cb_capture_fixed_continue, cap_session);
    }

    if(cap_session->wtap)
        capture_info_new_packets(to_read, cap_session->wtap, cap_session->cap_data_info);
}


/* Capture child told us how many dropped packets it counted.
 */
static void
capture_input_drops(capture_session *cap_session, guint32 dropped, const char* interface_name)
{
    if (interface_name != NULL) {
        ws_info("%u packet%s dropped from %s", dropped, plurality(dropped, "", "s"), interface_name);
    } else {
        ws_info("%u packet%s dropped", dropped, plurality(dropped, "", "s"));
    }

    ws_assert(cap_session->state == CAPTURE_RUNNING);

    cf_set_drops_known((capture_file *)cap_session->cf, TRUE);
    cf_set_drops((capture_file *)cap_session->cf, dropped);
}


/* Capture child told us that an error has occurred while starting/running
   the capture.
   The buffer we're handed has *two* null-terminated strings in it - a
   primary message and a secondary message, one right after the other.
   The secondary message might be a null string.
 */
static void
capture_input_error(capture_session *cap_session _U_, char *error_msg,
                    char *secondary_error_msg)
{
    gchar *safe_error_msg;
    gchar *safe_secondary_error_msg;

    ws_message("Error message from child: \"%s\", \"%s\"", error_msg, secondary_error_msg);

    ws_assert(cap_session->state == CAPTURE_PREPARING || cap_session->state == CAPTURE_RUNNING);

    safe_error_msg = simple_dialog_format_message(error_msg);
    if (secondary_error_msg != NULL && *secondary_error_msg != '\0') {
        /* We have both primary and secondary messages. */
        safe_secondary_error_msg = simple_dialog_format_message(secondary_error_msg);
        simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK, "%s%s%s\n\n%s",
                simple_dialog_primary_start(), safe_error_msg,
                simple_dialog_primary_end(), safe_secondary_error_msg);
        g_free(safe_secondary_error_msg);
    } else {
        /* We have only a primary message. */
        simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK, "%s%s%s",
                simple_dialog_primary_start(), safe_error_msg,
                simple_dialog_primary_end());
    }
    g_free(safe_error_msg);

    /* the capture child will close the sync_pipe if required, nothing to do for now */
}

/* Capture child told us that an error has occurred while parsing a
   capture filter when starting/running the capture.
 */
static void
capture_input_cfilter_error(capture_session *cap_session, guint i,
                            const char *error_message)
{
    capture_options *capture_opts = cap_session->capture_opts;
    dfilter_t *rfcode = NULL;
    gchar *safe_cfilter;
    gchar *safe_descr;
    gchar *safe_cfilter_error_msg;
    interface_options *interface_opts;

    ws_message("Capture filter error message from child: \"%s\"", error_message);

    ws_assert(cap_session->state == CAPTURE_PREPARING || cap_session->state == CAPTURE_RUNNING);
    ws_assert(i < capture_opts->ifaces->len);

    interface_opts = &g_array_index(capture_opts->ifaces, interface_options, i);
    safe_cfilter = simple_dialog_format_message(interface_opts->cfilter);
    safe_descr = simple_dialog_format_message(interface_opts->descr);
    safe_cfilter_error_msg = simple_dialog_format_message(error_message);
    /* Did the user try a display filter? */
    if (dfilter_compile(interface_opts->cfilter, &rfcode, NULL) && rfcode != NULL) {
        simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK,
                "%sInvalid capture filter \"%s\" for interface %s.%s\n"
                "\n"
                "That string looks like a valid display filter; however, it isn't a valid\n"
                "capture filter (%s).\n"
                "\n"
                "Note that display filters and capture filters don't have the same syntax,\n"
                "so you can't use most display filter expressions as capture filters.\n"
                "\n"
                "See the User's Guide for a description of the capture filter syntax.",
                simple_dialog_primary_start(), safe_cfilter, safe_descr,
                simple_dialog_primary_end(), safe_cfilter_error_msg);
        dfilter_free(rfcode);
    } else {
        simple_dialog(ESD_TYPE_ERROR, ESD_BTN_OK,
                "%sInvalid capture filter \"%s\" for interface %s.%s\n"
                "\n"
                "That string isn't a valid capture filter (%s).\n"
                "See the User's Guide for a description of the capture filter syntax.",
                simple_dialog_primary_start(), safe_cfilter, safe_descr,
                simple_dialog_primary_end(), safe_cfilter_error_msg);
    }
    g_free(safe_cfilter_error_msg);
    g_free(safe_descr);
    g_free(safe_cfilter);

    /* the capture child will close the sync_pipe if required, nothing to do for now */
}

/* capture child closed its side of the pipe, do the required cleanup */
static void
capture_input_closed(capture_session *cap_session, gchar *msg)
{
    capture_options *capture_opts = cap_session->capture_opts;
    int  err;

    ws_message("Capture stopped.");
    ws_assert(cap_session->state == CAPTURE_PREPARING || cap_session->state == CAPTURE_RUNNING);

    if (msg != NULL) {
        ESD_TYPE_E dlg_type = ESD_TYPE_ERROR;
        if (strstr(msg, " WARNING] ")) {
            dlg_type = ESD_TYPE_WARN;
        }
        /*
         * ws_log prefixes log messages with a timestamp delimited by " -- " and possibly
         * a function name delimited by "(): ". Log it to sterr, but omit it in the UI.
         */
        char *plain_msg = strstr(msg, "(): ");
        if (plain_msg != NULL) {
            plain_msg += strlen("(): ");
        } else if ((plain_msg = strstr(msg, " -- ")) != NULL) {
            plain_msg += strlen(" -- ");
        } else {
            plain_msg = msg;
        }
        ws_warning("%s", msg);
        simple_dialog(dlg_type, ESD_BTN_OK, "%s", plain_msg);
    }

    wtap_rec_cleanup(&cap_session->rec);
    ws_buffer_free(&cap_session->buf);
    if(cap_session->state == CAPTURE_PREPARING) {
        /* We started the capture child, but we didn't manage to start
           the capture process; note that the attempt to start it
           failed. */
        capture_callback_invoke(capture_cb_capture_failed, cap_session);
    } else {
        /* We started a capture; process what's left of the capture file if
           we were in "update list of packets in real time" mode, or process
           all of it if we weren't. */
        if(((capture_file*)cap_session->cf)->state == FILE_READ_IN_PROGRESS) {
            cf_read_status_t status;

            /* Read what remains of the capture file. */
            status = cf_finish_tail((capture_file *)cap_session->cf,
                                    &cap_session->rec, &cap_session->buf, &err,
                                    &cap_session->frame_dup_cache, cap_session->frame_cksum);

            // The real-time reading of the pcap is done. Now we can clear the
            // dup-frame cache, if present. But check that we actually have
            // data structures to clear (by checking frame-checksum); the user
            // could have changed the preference *during* the live capture.
            if (cap_session->frame_cksum != NULL) {
                fifo_string_cache_free(&cap_session->frame_dup_cache);
                g_checksum_free(cap_session->frame_cksum);
                cap_session->frame_cksum = NULL;
            }

            /* Tell the GUI we are not doing a capture any more.
               Must be done after the cf_finish_tail(), so file lengths are
               correctly displayed */
            cap_session->session_will_restart = FALSE;
            capture_callback_invoke(capture_cb_capture_update_finished, cap_session);

            /* Finish the capture. */
            switch (status) {

                case CF_READ_OK:
                    if (cap_session->count == 0 && !capture_opts->restart) {
                        simple_dialog(ESD_TYPE_INFO, ESD_BTN_OK,
                                "%sNo packets captured.%s\n"
                                "\n"
                                "As no data was captured, closing the %scapture file.\n"
                                "\n"
                                "\n"
                                "Help about capturing can be found at\n"
                                "\n"
                                "       " WS_WIKI_URL("CaptureSetup")
#ifdef _WIN32
                                "\n\n"
                                "Wireless (Wi-Fi/WLAN):\n"
                                "Try to switch off promiscuous mode in the Capture Options."
#endif
                                "",
                                simple_dialog_primary_start(), simple_dialog_primary_end(),
                                cf_is_tempfile((capture_file *)cap_session->cf) ? "temporary " : "");
                        cf_close((capture_file *)cap_session->cf);
                    }
                    break;
                case CF_READ_ERROR:
                    /* Just because we got an error, that doesn't mean we were unable
                       to read any of the file; we handle what we could get from the
                       file. */
                    break;

                case CF_READ_ABORTED:
                    /* Exit by leaving the main loop, so that any quit functions
                       we registered get called. */
                    exit_application(0);
                    break;
            }
        } else if (((capture_file*)cap_session->cf)->state == FILE_READ_PENDING) {
            /* first of all, we are not doing a capture any more */
            capture_callback_invoke(capture_cb_capture_fixed_finished, cap_session);

            /* this is a normal mode capture and if no error happened, read in the capture file data */
            if(capture_opts->save_file != NULL) {
                capture_input_read_all(cap_session, cf_is_tempfile((capture_file *)cap_session->cf),
                        cf_get_drops_known((capture_file *)cap_session->cf), cf_get_drops((capture_file *)cap_session->cf));
            }
        }
    }

    capture_info_ui_destroy(&cap_session->cap_data_info->ui);
    if(cap_session->wtap) {
        wtap_close(cap_session->wtap);
        cap_session->wtap = NULL;
    }

    cap_session->state = CAPTURE_STOPPED;

    /* if we couldn't open a capture file, there's nothing more for us to do */
    if(capture_opts->save_file == NULL) {
        cf_close((capture_file *)cap_session->cf);
        return;
    }

    /* does the user wants to restart the current capture? */
    if(capture_opts->restart) {
        capture_opts->restart = FALSE;

        /* If we have a ring buffer, the original save file has been overwritten
           with the "ring filename".  Restore it before starting again */
        if ((capture_opts->multi_files_on) && (capture_opts->orig_save_file != NULL)) {
            g_free(capture_opts->save_file);
            capture_opts->save_file = g_strdup(capture_opts->orig_save_file);
        }

        /* If it was a tempfile, throw away the old filename (so it will become a tempfile again) */
        if (cf_is_tempfile((capture_file *)cap_session->cf)) {
            g_free(capture_opts->save_file);
            capture_opts->save_file = NULL;
        }
    } else {
        /* We're not doing a capture any more, so we don't have a save file. */
        g_free(capture_opts->save_file);
        capture_opts->save_file = NULL;
    }
}

if_stat_cache_t *
capture_stat_start(capture_options *capture_opts)
{
    int stat_fd;
    ws_process_id fork_child;
    gchar *msg;
    if_stat_cache_t *sc = g_new0(if_stat_cache_t, 1);
    if_stat_cache_item_t *sc_item;
    guint i;
    interface_t *device;

    sc->stat_fd = -1;
    sc->fork_child = WS_INVALID_PID;

    /* Fire up dumpcap. */
    /*
     * XXX - on systems with BPF, the number of BPF devices limits the
     * number of devices on which you can capture simultaneously.
     *
     * This means that
     *
     *    1) this might fail if you run out of BPF devices
     *
     * and
     *
     *    2) opening every interface could leave too few BPF devices
     *       for *other* programs.
     *
     * It also means the system could end up getting a lot of traffic
     * that it has to pass through the networking stack and capture
     * mechanism, so opening all the devices and presenting packet
     * counts might not always be a good idea.
     */
    if (sync_interface_stats_open(&stat_fd, &fork_child, &msg, NULL) == 0) {
        sc->stat_fd = stat_fd;
        sc->fork_child = fork_child;

        /* Initialize the cache */
        for (i = 0; i < capture_opts->all_ifaces->len; i++) {
            device = &g_array_index(capture_opts->all_ifaces, interface_t, i);
            if (device->type != IF_PIPE && device->type != IF_EXTCAP) {
                sc_item = g_new0(if_stat_cache_item_t, 1);
                ws_assert(device->if_info.name);
                sc_item->name = g_strdup(device->if_info.name);
                sc->cache_list = g_list_prepend(sc->cache_list, sc_item);
            }
        }
    } else {
        ws_warning("%s", msg);
        g_free(msg); /* XXX: should we display this to the user via the GUI? */
    }
    return sc;
}

#define MAX_STAT_LINE_LEN 500

static void
capture_stat_cache_update(if_stat_cache_t *sc)
{
    gchar stat_line[MAX_STAT_LINE_LEN] = "";
    gchar **stat_parts;
    GList *sc_entry;
    if_stat_cache_item_t *sc_item;

    if (!sc || sc->fork_child == WS_INVALID_PID) {
        return;
    }

    while (sync_pipe_gets_nonblock(sc->stat_fd, stat_line, MAX_STAT_LINE_LEN) > 0) {
        g_strstrip(stat_line);
        stat_parts = g_strsplit(stat_line, "\t", 3);
        if (stat_parts[0] == NULL || stat_parts[1] == NULL ||
                stat_parts[2] == NULL) {
            g_strfreev(stat_parts);
            continue;
        }
        for (sc_entry = sc->cache_list; sc_entry != NULL; sc_entry = g_list_next(sc_entry)) {
            sc_item = (if_stat_cache_item_t *)sc_entry->data;
            if (strcmp(sc_item->name, stat_parts[0]) == 0) {
                sc_item->ps.ps_recv = (u_int) strtoul(stat_parts[1], NULL, 10);
                sc_item->ps.ps_drop = (u_int) strtoul(stat_parts[2], NULL, 10);
            }
        }
        g_strfreev(stat_parts);
    }
}

gboolean
capture_stats(if_stat_cache_t *sc, char *ifname, struct pcap_stat *ps)
{
    GList *sc_entry;
    if_stat_cache_item_t *sc_item;

    if (!sc || sc->fork_child == WS_INVALID_PID || !ifname || !ps) {
        return FALSE;
    }

    capture_stat_cache_update(sc);
    for (sc_entry = sc->cache_list; sc_entry != NULL; sc_entry = g_list_next(sc_entry)) {
        sc_item = (if_stat_cache_item_t *)sc_entry->data;
        if (strcmp(sc_item->name, ifname) == 0) {
            memcpy(ps, &sc_item->ps, sizeof(struct pcap_stat));
            return TRUE;
        }
    }
    return FALSE;
}

void
capture_stat_stop(if_stat_cache_t *sc)
{
    GList *sc_entry;
    if_stat_cache_item_t *sc_item;
    int ret;
    gchar *msg;

    if (!sc) {
        return;
    }

    if (sc->fork_child != WS_INVALID_PID) {
        ret = sync_interface_stats_close(&sc->stat_fd, &sc->fork_child, &msg);
        if (ret == -1) {
            /* XXX - report failure? */
            g_free(msg);
        }
    }

    for (sc_entry = sc->cache_list; sc_entry != NULL; sc_entry = g_list_next(sc_entry)) {
        sc_item = (if_stat_cache_item_t *)sc_entry->data;
        g_free(sc_item->name);
        g_free(sc_item);
    }
    g_list_free(sc->cache_list);
    g_free(sc);
}

/* Initialize a capture session for our callbacks. */
void
capture_input_init(capture_session *cap_session, capture_file *cf)
{
    capture_session_init(cap_session, cf,
                         capture_input_new_file, capture_input_new_packets,
                         capture_input_drops, capture_input_error,
                         capture_input_cfilter_error, capture_input_closed);
}
#endif /* HAVE_LIBPCAP */