wireshark/capinfos.c

/* capinfos.c
 * Reports capture file information including # of packets, duration, others
 *
 * Copyright 2004 Ian Schorr
 *
 * $Id$
 *
 * 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.
 */

/*
 * 2009-09-19: jyoung
 *
 * New capinfos features
 *
 * Continue processing additional files after
 * a wiretap open failure.  The new -C option
 * reverts to capinfos' original behavior which
 * is to cancel any further file processing at
 * first file open failure.
 *
 * Change the behavior of how the default display
 * of all infos is initiated.  This gets rid of a
 * special post getopt() argument count test.
 *
 * Add new table output format (with related options)
 * This feature allows outputting the various infos
 * into a tab delimited text file, or to a comma
 * separated variables file (*.csv) instead of the
 * original "long" format.
 *
 * 2011-04-05: wmeier
 * behaviour changed: Upon exit capinfos will return
 *  an error status if an error occurred at any
 *  point during "continuous" file processing.
 *  (Previously a success status was always
 *   returned if the -C option was not used).
 *

 */


#include "config.h"

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

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif

#include <glib.h>

#include <epan/packet.h>
#include <epan/filesystem.h>
#include <epan/plugins.h>
#include <epan/report_err.h>
#include "wtap.h"
#include <wsutil/privileges.h>

#ifdef HAVE_LIBGCRYPT
#include <gcrypt.h>
#include <wsutil/file_util.h>
#endif

#ifndef HAVE_GETOPT
#include "wsutil/wsgetopt.h"
#endif

#ifdef _WIN32
#include <wsutil/unicode-utils.h>
#endif /* _WIN32 */

#include "svnversion.h"

/*
 * By default capinfos now continues processing
 * the next filename if and when wiretap detects
 * a problem opening a file.
 * Use the '-C' option to revert back to original
 * capinfos behavior which is to abort any
 * additional file processing at first open file
 * failure.
 */

static gboolean continue_after_wtap_open_offline_failure = TRUE;

/*
 * table report variables
 */

static gboolean long_report = TRUE;         /* By default generate long report       */
static gchar table_report_header = TRUE;    /* Generate column header by default     */
static gchar field_separator = '\t';        /* Use TAB as field separator by default */
static gchar quote_char = '\0';             /* Do NOT quote fields by default        */

/*
 * capinfos has the ability to report on a number of
 * various characteristics ("infos") for each input file.
 *
 * By default reporting of all info fields is enabled.
 *
 * Optionally the reporting of any specific info field
 * or combination of info fields can be enabled with
 * individual options.
 */

static gboolean report_all_infos = TRUE;    /* Report all infos           */

static gboolean cap_file_type = TRUE;       /* Report capture type        */
static gboolean cap_file_encap = TRUE;      /* Report encapsulation       */
static gboolean cap_snaplen = TRUE;         /* Packet size limit (snaplen)*/
static gboolean cap_packet_count = TRUE;    /* Report packet count        */
static gboolean cap_file_size = TRUE;       /* Report file size           */

static gboolean cap_data_size = TRUE;       /* Report packet byte size    */
static gboolean cap_duration = TRUE;        /* Report capture duration    */
static gboolean cap_start_time = TRUE;      /* Report capture start time  */
static gboolean cap_end_time = TRUE;        /* Report capture end time    */
static gboolean time_as_secs = FALSE;       /* Report time values as raw seconds */

static gboolean cap_data_rate_byte = TRUE;  /* Report data rate bytes/sec */
static gboolean cap_data_rate_bit = TRUE;   /* Report data rate bites/sec */
static gboolean cap_packet_size = TRUE;     /* Report average packet size */
static gboolean cap_packet_rate = TRUE;     /* Report average packet rate */
static gboolean cap_order = TRUE;           /* Report if packets are in chronological order (True/False) */

#ifdef HAVE_LIBGCRYPT
static gboolean cap_file_hashes = TRUE;     /* Calculate file hashes */
#endif

#ifdef USE_GOPTION
static gboolean cap_help = FALSE;
static gboolean table_report = FALSE;

static GOptionEntry general_entries[] =
{
/* General */
  { "type", 't', 0, G_OPTION_ARG_NONE, &cap_file_type,
    "display the capture file type", NULL },
  { "Encapsulation", 'E', 0, G_OPTION_ARG_NONE, &cap_file_encap,
    "display the capture file encapsulation", NULL },
#ifdef HAVE_LIBGCRYPT
  { "Hash", 'H', 0, G_OPTION_ARG_NONE, &cap_file_hashes,
    "display the SHA1, RMD160, and MD5 hashes of the file", NULL },
#endif /* HAVE_LIBGCRYPT */
 { NULL,'\0',0,G_OPTION_ARG_NONE,NULL,NULL,NULL }
};
static GOptionEntry size_entries[] =
{
/* Size */
  { "packets", 'c', 0, G_OPTION_ARG_NONE, &cap_packet_count,
    "display the number of packets", NULL },
  { "size", 's', 0, G_OPTION_ARG_NONE, &cap_file_size,
    "display the size of the file (in bytes)", NULL },
  { "tot-len-of-pkts", 'd', 0, G_OPTION_ARG_NONE, &cap_data_size,
    "display the total length of all packets (in bytes)", NULL },
  { "snap", 'l', 0, G_OPTION_ARG_NONE, &cap_snaplen,
    "display the packet size limit (snapshot length)", NULL },
  { NULL,'\0',0,G_OPTION_ARG_NONE,NULL,NULL,NULL }
};
static GOptionEntry time_entries[] =
{
/* Time */
  { "duration", 'u', 0, G_OPTION_ARG_NONE, &cap_duration,
    "display the capture duration (in seconds)", NULL },
  { "start", 'a', 0, G_OPTION_ARG_NONE, &cap_start_time,
    "display the capture start time", NULL },
  { "end", 'e', 0, G_OPTION_ARG_NONE, &cap_end_time,
    "display the capture end time", NULL },
  { "cron", 'o', 0, G_OPTION_ARG_NONE, &cap_order,
    "display the capture file chronological status (True/False)", NULL },
  { "start-end-time-sec", 'S', 0, G_OPTION_ARG_NONE, &time_as_secs,
    "display start and end times as seconds", NULL },
  { NULL,'\0',0,G_OPTION_ARG_NONE,NULL,NULL,NULL }
};

static GOptionEntry stats_entries[] =
{
/* Statistics */
  { "bytes", 'y', 0, G_OPTION_ARG_NONE, &cap_data_rate_byte,
    "display average data rate (in bytes/s)", NULL },
  { "bits", 'i', 0, G_OPTION_ARG_NONE, &cap_data_rate_bit,
    "display average data rate (in bits/s)", NULL },
  { "packet-bytes", 'z', 0, G_OPTION_ARG_NONE, &cap_packet_size,
    "display average packet size (in bytes)", NULL },
  { "packets", 'x', 0, G_OPTION_ARG_NONE, &cap_packet_rate,
    "display average packet rate (in packets/s)", NULL },
  { NULL,'\0',0,G_OPTION_ARG_NONE,NULL,NULL,NULL }
};

static GOptionEntry output_format_entries[] =
{
/* Output format */
  { "long", 'L', 0, G_OPTION_ARG_NONE, &long_report,
    "generate long report (default)", NULL },
  { "Table", 'T', 0, G_OPTION_ARG_NONE, &table_report,
    "generate table report", NULL },
  { NULL,'\0',0,G_OPTION_ARG_NONE,NULL,NULL,NULL }
};

static GOptionEntry table_report_entries[] =
{
/* Table report */
  { "header-rec", 'R', 0, G_OPTION_ARG_NONE, &table_report_header,
    "generate header record (default)", NULL },
  { "no-table", 'r', 0, G_OPTION_ARG_NONE, &table_report_header,
    "do not generate header record", NULL },
  { NULL,'\0',0,G_OPTION_ARG_NONE,NULL,NULL,NULL }
};

static GOptionEntry misc_entries[] =
{
  { "helpcompat", 'h', 0, G_OPTION_ARG_NONE, &cap_help,
    "display help", NULL },
 { NULL,'\0',0,G_OPTION_ARG_NONE,NULL,NULL,NULL }
};

GOptionContext *ctx;
GOptionGroup *general_grp, *size_grp, *time_grp, *stats_grp, *output_grp, *table_report_grp;
GError *parse_err = NULL;

#endif /* USE_GOPTION */

#ifdef HAVE_LIBGCRYPT
#define HASH_SIZE_SHA1 20
#define HASH_SIZE_RMD160 20
#define HASH_SIZE_MD5 16

#define HASH_STR_SIZE (41) /* Max hash size * 2 + '\0' */
#define HASH_BUF_SIZE (1024 * 1024)


static gchar file_sha1[HASH_STR_SIZE];
static gchar file_rmd160[HASH_STR_SIZE];
static gchar file_md5[HASH_STR_SIZE];

#define FILE_HASH_OPT "H"
#else
#define FILE_HASH_OPT ""
#endif /* HAVE_LIBGCRYPT */

/*
 * If we have at least two packets with time stamps, and they're not in
 * order - i.e., the later packet has a time stamp older than the earlier
 * packet - the time stamps are known not to be in order.
 *
 * If every packet has a time stamp, and they're all in order, the time
 * stamp is known to be in order.
 *
 * Otherwise, we have no idea.
 */
typedef enum {
  IN_ORDER,
  NOT_IN_ORDER,
  ORDER_UNKNOWN
} order_t;

typedef struct _capture_info {
  const char    *filename;
  guint16       file_type;
  gboolean      iscompressed;
  int           file_encap;
  gint64        filesize;

  guint64       packet_bytes;
  gboolean      times_known;
  double        start_time;
  double        stop_time;
  guint32       packet_count;
  gboolean      snap_set;                /* If set in capture file header      */
  guint32       snaplen;                 /* value from the capture file header */
  guint32       snaplen_min_inferred;    /* If caplen < len for 1 or more rcds */
  guint32       snaplen_max_inferred;    /*  ...                               */
  gboolean      drops_known;
  guint32       drop_count;

  double        duration;
  double        packet_rate;
  double        packet_size;
  double        data_rate;              /* in bytes */
  gboolean      know_order;
  order_t       order;

  int          *encap_counts;           /* array of per_packet encap counts; array has one entry per wtap_encap type */
} capture_info;


static void
enable_all_infos(void)
{
  report_all_infos = TRUE;

  cap_file_type = TRUE;
  cap_file_encap = TRUE;
  cap_snaplen = TRUE;
  cap_packet_count = TRUE;
  cap_file_size = TRUE;

  cap_data_size = TRUE;
  cap_duration = TRUE;
  cap_start_time = TRUE;
  cap_end_time = TRUE;
  cap_order = TRUE;

  cap_data_rate_byte = TRUE;
  cap_data_rate_bit = TRUE;
  cap_packet_size = TRUE;
  cap_packet_rate = TRUE;

#ifdef HAVE_LIBGCRYPT
  cap_file_hashes = TRUE;
#endif /* HAVE_LIBGCRYPT */
}

static void
disable_all_infos(void)
{
  report_all_infos   = FALSE;

  cap_file_type      = FALSE;
  cap_file_encap     = FALSE;
  cap_snaplen        = FALSE;
  cap_packet_count   = FALSE;
  cap_file_size      = FALSE;

  cap_data_size      = FALSE;
  cap_duration       = FALSE;
  cap_start_time     = FALSE;
  cap_end_time       = FALSE;
  cap_order          = FALSE;

  cap_data_rate_byte = FALSE;
  cap_data_rate_bit  = FALSE;
  cap_packet_size    = FALSE;
  cap_packet_rate    = FALSE;

#ifdef HAVE_LIBGCRYPT
  cap_file_hashes = FALSE;
#endif /* HAVE_LIBGCRYPT */
}

static const gchar *
order_string(order_t order)
{
  switch (order) {

  case IN_ORDER:
    return "True";

  case NOT_IN_ORDER:
    return "False";

  case ORDER_UNKNOWN:
    return "Unknown";

  default:
    return "???";  /* "cannot happen" (the next step is "Profit!") */
  }
}

static gchar *
time_string(time_t timer, capture_info *cf_info, gboolean want_lf)
{
  const gchar *lf = want_lf ? "\n" : "";
  static gchar time_string_buf[20];
  char *time_string_ctime;

  if (cf_info->times_known && cf_info->packet_count > 0) {
    if (time_as_secs) {
      /* XXX - Would it be useful to show sub-second precision? */
      g_snprintf(time_string_buf, 20, "%lu%s", (unsigned long)timer, lf);
      return time_string_buf;
    } else {
#if (defined _WIN32) && (_MSC_VER < 1500)
      /* calling localtime(), and thus ctime(), on MSVC 2005 with huge values causes it to crash */
      /* XXX - find the exact value that still does work */
      /* XXX - using _USE_32BIT_TIME_T might be another way to circumvent this problem */
      if (timer > 2000000000) {
        time_string_ctime = NULL;
      } else
#endif
      time_string_ctime = ctime(&timer);
      if (time_string_ctime == NULL) {
      	g_snprintf(time_string_buf, 20, "Not representable%s", lf);
        return time_string_buf;
      }
      if (!want_lf) {
        /*
         * The ctime() function returns a string formatted as:
         *   "Www Mmm dd hh:mm:ss yyyy\n"
         * The unwanted '\n' is the 24th character.
         */
        time_string_ctime[24] = '\0';
      }
      return time_string_ctime;
    }
  }

  g_snprintf(time_string_buf, 15, "n/a%s", lf);
  return time_string_buf;
}

static double
secs_nsecs(const struct wtap_nstime * nstime)
{
  return (nstime->nsecs / 1000000000.0) + (double)nstime->secs;
}

static void print_value(const gchar *text_p1, gint width, const gchar *text_p2, double value) {
  if (value > 0.0)
    printf("%s%.*f%s\n", text_p1, width, value, text_p2);
  else
    printf("%sn/a\n", text_p1);
}

static void
print_stats(const gchar *filename, capture_info *cf_info)
{
  const gchar           *file_type_string, *file_encap_string;
  time_t                start_time_t;
  time_t                stop_time_t;

  /* Build printable strings for various stats */
  file_type_string = wtap_file_type_string(cf_info->file_type);
  file_encap_string = wtap_encap_string(cf_info->file_encap);
  start_time_t = (time_t)cf_info->start_time;
  stop_time_t = (time_t)cf_info->stop_time;

  if (filename)           printf     ("File name:           %s\n", filename);
  if (cap_file_type)      printf     ("File type:           %s%s\n",
                                      file_type_string,
                                      cf_info->iscompressed ? " (gzip compressed)" : "");
  if (cap_file_encap)     printf     ("File encapsulation:  %s\n", file_encap_string);
  if (cap_file_encap && (cf_info->file_encap == WTAP_ENCAP_PER_PACKET)) {
    int i;
    for (i=0; i<WTAP_NUM_ENCAP_TYPES; i++) {
      if (cf_info->encap_counts[i] > 0)
        printf("                       %s\n", wtap_encap_string(i));
    }
  }
  if (cap_snaplen && cf_info->snap_set)
                          printf     ("Packet size limit:   file hdr: %u bytes\n", cf_info->snaplen);
  else if(cap_snaplen && !cf_info->snap_set)
                          printf     ("Packet size limit:   file hdr: (not set)\n");
  if (cf_info->snaplen_max_inferred > 0) {
    if (cf_info->snaplen_min_inferred == cf_info->snaplen_max_inferred)
                          printf     ("Packet size limit:   inferred: %u bytes\n", cf_info->snaplen_min_inferred);
    else
                          printf     ("Packet size limit:   inferred: %u bytes - %u bytes (range)\n",
                                      cf_info->snaplen_min_inferred, cf_info->snaplen_max_inferred);
  }
  if (cap_packet_count)   printf     ("Number of packets:   %u\n", cf_info->packet_count);
  if (cap_file_size)      printf     ("File size:           %" G_GINT64_MODIFIER "d bytes\n", cf_info->filesize);
  if (cap_data_size)      printf     ("Data size:           %" G_GINT64_MODIFIER "u bytes\n", cf_info->packet_bytes);
  if (cf_info->times_known) {
    if (cap_duration)
                          print_value("Capture duration:    ", 0, " seconds",   cf_info->duration);
    if (cap_start_time)
                          printf     ("Start time:          %s", time_string(start_time_t, cf_info, TRUE));
    if (cap_end_time)
                          printf     ("End time:            %s", time_string(stop_time_t, cf_info, TRUE));
    if (cap_data_rate_byte)
                          print_value("Data byte rate:      ", 2, " bytes/sec",   cf_info->data_rate);
    if (cap_data_rate_bit)
                          print_value("Data bit rate:       ", 2, " bits/sec",    cf_info->data_rate*8);
  }
  if (cap_packet_size)    printf     ("Average packet size: %.2f bytes\n",        cf_info->packet_size);
  if (cf_info->times_known) {
    if (cap_packet_rate)
                          print_value("Average packet rate: ", 2, " packets/sec", cf_info->packet_rate);
  }
#ifdef HAVE_LIBGCRYPT
  if (cap_file_hashes) {
                          printf     ("SHA1:                %s\n", file_sha1);
                          printf     ("RIPEMD160:           %s\n", file_rmd160);
                          printf     ("MD5:                 %s\n", file_md5);
  }
#endif /* HAVE_LIBGCRYPT */
  if (cap_order)          printf     ("Strict time order:   %s\n", order_string(cf_info->order));
}

static void
putsep(void)
{
  if (field_separator) putchar(field_separator);
}

static void
putquote(void)
{
  if (quote_char) putchar(quote_char);
}

static void
print_stats_table_header_label(const gchar *label)
{
  putsep();
  putquote();
  printf("%s", label);
  putquote();
}

static void
print_stats_table_header(void)
{
  putquote();
  printf("File name");
  putquote();

  if (cap_file_type)      print_stats_table_header_label("File type");
  if (cap_file_encap)     print_stats_table_header_label("File encapsulation");
  if (cap_snaplen)        print_stats_table_header_label("Packet size limit");
  if (cap_snaplen)        print_stats_table_header_label("Packet size limit min (inferred)");
  if (cap_snaplen)        print_stats_table_header_label("Packet size limit max (inferred)");
  if (cap_packet_count)   print_stats_table_header_label("Number of packets");
  if (cap_file_size)      print_stats_table_header_label("File size (bytes)");
  if (cap_data_size)      print_stats_table_header_label("Data size (bytes)");
  if (cap_duration)       print_stats_table_header_label("Capture duration (seconds)");
  if (cap_start_time)     print_stats_table_header_label("Start time");
  if (cap_end_time)       print_stats_table_header_label("End time");
  if (cap_data_rate_byte) print_stats_table_header_label("Data byte rate (bytes/sec)");
  if (cap_data_rate_bit)  print_stats_table_header_label("Data bit rate (bits/sec)");
  if (cap_packet_size)    print_stats_table_header_label("Average packet size (bytes)");
  if (cap_packet_rate)    print_stats_table_header_label("Average packet rate (packets/sec)");
#ifdef HAVE_LIBGCRYPT
  if (cap_file_hashes) {
                          print_stats_table_header_label("SHA1");
                          print_stats_table_header_label("RIPEMD160");
                          print_stats_table_header_label("MD5");
  }
#endif /* HAVE_LIBGCRYPT */
  if (cap_order)          print_stats_table_header_label("Strict time order");

  printf("\n");
}

static void
print_stats_table(const gchar *filename, capture_info *cf_info)
{
  const gchar           *file_type_string, *file_encap_string;
  time_t                start_time_t;
  time_t                stop_time_t;

  /* Build printable strings for various stats */
  file_type_string = wtap_file_type_string(cf_info->file_type);
  file_encap_string = wtap_encap_string(cf_info->file_encap);
  start_time_t = (time_t)cf_info->start_time;
  stop_time_t = (time_t)cf_info->stop_time;

  if (filename) {
    putquote();
    printf("%s", filename);
    putquote();
  }

  if (cap_file_type) {
    putsep();
    putquote();
    printf("%s", file_type_string);
    putquote();
  }

  /* ToDo: If WTAP_ENCAP_PER_PACKET, show the list of encapsulations encountered;
   *       Output a line for each different encap with all fields repeated except
   *        the encapsulation field which has "Per Packet: ..." for each
   *        encapsulation type seen ?
   */
  if (cap_file_encap) {
    putsep();
    putquote();
    printf("%s", file_encap_string);
    putquote();
  }

  if (cap_snaplen) {
    putsep();
    putquote();
    if(cf_info->snap_set)
      printf("%u", cf_info->snaplen);
    else
      printf("(not set)");
    putquote();
    if (cf_info->snaplen_max_inferred > 0) {
      putsep();
      putquote();
      printf("%u", cf_info->snaplen_min_inferred);
      putquote();
      putsep();
      putquote();
      printf("%u", cf_info->snaplen_max_inferred);
      putquote();
    }
    else {
      putsep();
      putquote();
      printf("n/a");
      putquote();
      putsep();
      putquote();
      printf("n/a");
      putquote();
    }
  }

  if (cap_packet_count) {
    putsep();
    putquote();
    printf("%u", cf_info->packet_count);
    putquote();
  }

  if (cap_file_size) {
    putsep();
    putquote();
    printf("%" G_GINT64_MODIFIER "d", cf_info->filesize);
    putquote();
  }

  if (cap_data_size) {
    putsep();
    putquote();
    printf("%" G_GINT64_MODIFIER "u", cf_info->packet_bytes);
    putquote();
  }

  if (cap_duration) {
    putsep();
    putquote();
    if (cf_info->times_known)
      printf("%f", cf_info->duration);
    else
      printf("n/a");
    putquote();
  }

  if (cap_start_time) {
    putsep();
    putquote();
    printf("%s", time_string(start_time_t, cf_info, FALSE));
    putquote();
  }

  if (cap_end_time) {
    putsep();
    putquote();
    printf("%s", time_string(stop_time_t, cf_info, FALSE));
    putquote();
  }

  if (cap_data_rate_byte) {
    putsep();
    putquote();
    if (cf_info->times_known)
      printf("%.2f", cf_info->data_rate);
    else
      printf("n/a");
    putquote();
  }

  if (cap_data_rate_bit) {
    putsep();
    putquote();
    if (cf_info->times_known)
      printf("%.2f", cf_info->data_rate*8);
    else
      printf("n/a");
    putquote();
  }

  if (cap_packet_size) {
    putsep();
    putquote();
    printf("%.2f", cf_info->packet_size);
    putquote();
  }

  if (cap_packet_rate) {
    putsep();
    putquote();
    if (cf_info->times_known)
      printf("%.2f", cf_info->packet_rate);
    else
      printf("n/a");
    putquote();
  }

#ifdef HAVE_LIBGCRYPT
  if (cap_file_hashes) {
    putsep();
    putquote();
    printf("%s", file_sha1);
    putquote();

    putsep();
    putquote();
    printf("%s", file_rmd160);
    putquote();

    putsep();
    putquote();
    printf("%s", file_md5);
    putquote();
  }
#endif /* HAVE_LIBGCRYPT */

  if (cap_order) {
    putsep();
    putquote();
    printf("%s", order_string(cf_info->order));
    putquote();
  }

  printf("\n");
}

static int
process_cap_file(wtap *wth, const char *filename)
{
  int                   err;
  gchar                 *err_info;
  gint64                size;
  gint64                data_offset;

  guint32               packet = 0;
  gint64                bytes  = 0;
  guint32               snaplen_min_inferred = 0xffffffff;
  guint32               snaplen_max_inferred =          0;
  const struct wtap_pkthdr *phdr;
  capture_info          cf_info;
  gboolean		have_times = TRUE;
  double                start_time = 0;
  double                stop_time  = 0;
  double                cur_time   = 0;
  double		prev_time = 0;
  gboolean		know_order = FALSE;
  order_t		order = IN_ORDER;

  cf_info.encap_counts = g_malloc0(WTAP_NUM_ENCAP_TYPES * sizeof(int));

  /* Tally up data that we need to parse through the file to find */
  while (wtap_read(wth, &err, &err_info, &data_offset))  {
    phdr = wtap_phdr(wth);
    if (phdr->presence_flags & WTAP_HAS_TS) {
      prev_time = cur_time;