Avoid using a global variable when it's not needed

[tcpdump] / tcpdump.c

/*
 * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Support for splitting captures into multiple files with a maximum
 * file size:
 *
 * Copyright (c) 2001
 *      Seth Webster <swebster@sst.ll.mit.edu>
 */

#ifndef lint
static const char copyright[] _U_ =
    "@(#) Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000\n\
The Regents of the University of California.  All rights reserved.\n";
#endif

/*
 * tcpdump - dump traffic on a network
 *
 * First written in 1987 by Van Jacobson, Lawrence Berkeley Laboratory.
 * Mercilessly hacked and occasionally improved since then via the
 * combined efforts of Van, Steve McCanne and Craig Leres of LBL.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

/*
 * Mac OS X may ship pcap.h from libpcap 0.6 with a libpcap based on
 * 0.8.  That means it has pcap_findalldevs() but the header doesn't
 * define pcap_if_t, meaning that we can't actually *use* pcap_findalldevs().
 */
#ifdef HAVE_PCAP_FINDALLDEVS
#ifndef HAVE_PCAP_IF_T
#undef HAVE_PCAP_FINDALLDEVS
#endif
#endif

#include <netdissect-stdinc.h>

#include <sys/stat.h>

#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif

#ifdef HAVE_LIBCRYPTO
#include <openssl/crypto.h>
#endif

#ifdef HAVE_GETOPT_LONG
#include <getopt.h>
#else
#include "getopt_long.h"
#endif
/* Capsicum-specific code requires macros from <net/bpf.h>, which will fail
 * to compile if <pcap.h> has already been included; including the headers
 * in the opposite order works fine.
 */
#ifdef HAVE_CAPSICUM
#include <sys/capability.h>
#include <sys/ioccom.h>
#include <net/bpf.h>
#include <libgen.h>
#endif  /* HAVE_CAPSICUM */
#include <pcap.h>
#include <signal.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#ifndef _WIN32
#include <sys/wait.h>
#include <sys/resource.h>
#include <pwd.h>
#include <grp.h>
#endif /* _WIN32 */

/* capabilities convenience library */
/* If a code depends on HAVE_LIBCAP_NG, it depends also on HAVE_CAP_NG_H.
 * If HAVE_CAP_NG_H is not defined, undefine HAVE_LIBCAP_NG.
 * Thus, the later tests are done only on HAVE_LIBCAP_NG.
 */
#ifdef HAVE_LIBCAP_NG
#ifdef HAVE_CAP_NG_H
#include <cap-ng.h>
#else
#undef HAVE_LIBCAP_NG
#endif /* HAVE_CAP_NG_H */
#endif /* HAVE_LIBCAP_NG */

#include "netdissect.h"
#include "interface.h"
#include "addrtoname.h"
#include "machdep.h"
#include "setsignal.h"
#include "gmt2local.h"
#include "pcap-missing.h"
#include "ascii_strcasecmp.h"

#include "print.h"

#ifndef PATH_MAX
#define PATH_MAX 1024
#endif

#ifdef SIGINFO
#define SIGNAL_REQ_INFO SIGINFO
#elif SIGUSR1
#define SIGNAL_REQ_INFO SIGUSR1
#endif

static int Bflag;                       /* buffer size */
static int Cflag;                       /* rotate dump files after this many bytes */
static int Cflag_count;                 /* Keep track of which file number we're writing */
static int Dflag;                       /* list available devices and exit */
/*
 * This is exported because, in some versions of libpcap, if libpcap
 * is built with optimizer debugging code (which is *NOT* the default
 * configuration!), the library *imports*(!) a variable named dflag,
 * under the expectation that tcpdump is exporting it, to govern
 * how much debugging information to print when optimizing
 * the generated BPF code.
 *
 * This is a horrible hack; newer versions of libpcap don't import
 * dflag but, instead, *if* built with optimizer debugging code,
 * *export* a routine to set that flag.
 */
int dflag;                              /* print filter code */
static int Gflag;                       /* rotate dump files after this many seconds */
static int Gflag_count;                 /* number of files created with Gflag rotation */
static time_t Gflag_time;               /* The last time_t the dump file was rotated. */
static int Lflag;                       /* list available data link types and exit */
static int Iflag;                       /* rfmon (monitor) mode */
#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
static int Jflag;                       /* list available time stamp types */
#endif
static int jflag = -1;                  /* packet time stamp source */
static int pflag;                       /* don't go promiscuous */
#ifdef HAVE_PCAP_SETDIRECTION
static int Qflag = -1;                  /* restrict captured packet by send/receive direction */
#endif
static int Uflag;                       /* "unbuffered" output of dump files */
static int Wflag;                       /* recycle output files after this number of files */
static int WflagChars;
static char *zflag = NULL;              /* compress each savefile using a specified command (like gzip or bzip2) */
static int immediate_mode;

static int infodelay;
static int infoprint;

char *program_name;

/* Forwards */
static void error(const char *, ...)
     __attribute__((noreturn))
#ifdef __ATTRIBUTE___FORMAT_OK
     __attribute__((format (printf, 1, 2)))
#endif /* __ATTRIBUTE___FORMAT_OK */
     ;
static void warning(const char *, ...)
#ifdef __ATTRIBUTE___FORMAT_OK
     __attribute__((format (printf, 1, 2)))
#endif /* __ATTRIBUTE___FORMAT_OK */
     ;
static void exit_tcpdump(int) __attribute__((noreturn));
static RETSIGTYPE cleanup(int);
static RETSIGTYPE child_cleanup(int);
static void print_version(void);
static void print_usage(void);
static void show_tstamp_types_and_exit(pcap_t *, const char *device) __attribute__((noreturn));
static void show_dlts_and_exit(pcap_t *, const char *device) __attribute__((noreturn));
#ifdef HAVE_PCAP_FINDALLDEVS
static void show_devices_and_exit (void) __attribute__((noreturn));
#endif

static void print_packet(u_char *, const struct pcap_pkthdr *, const u_char *);
static void dump_packet_and_trunc(u_char *, const struct pcap_pkthdr *, const u_char *);
static void dump_packet(u_char *, const struct pcap_pkthdr *, const u_char *);
static void droproot(const char *, const char *);

#ifdef SIGNAL_REQ_INFO
RETSIGTYPE requestinfo(int);
#endif

#if defined(USE_WIN32_MM_TIMER)
  #include <MMsystem.h>
  static UINT timer_id;
  static void CALLBACK verbose_stats_dump(UINT, UINT, DWORD_PTR, DWORD_PTR, DWORD_PTR);
#elif defined(HAVE_ALARM)
  static void verbose_stats_dump(int sig);
#endif

static void info(int);
static u_int packets_captured;

#ifdef HAVE_PCAP_FINDALLDEVS
static const struct tok status_flags[] = {
#ifdef PCAP_IF_UP
        { PCAP_IF_UP,       "Up"       },
#endif
#ifdef PCAP_IF_RUNNING
        { PCAP_IF_RUNNING,  "Running"  },
#endif
        { PCAP_IF_LOOPBACK, "Loopback" },
        { 0, NULL }
};
#endif

static pcap_t *pd;

static int supports_monitor_mode;

extern int optind;
extern int opterr;
extern char *optarg;

struct dump_info {
        char    *WFileName;
        char    *CurrentFileName;
        pcap_t  *pd;
        pcap_dumper_t *p;
#ifdef HAVE_CAPSICUM
        int     dirfd;
#endif
};

#if defined(HAVE_PCAP_SET_PARSER_DEBUG)
/*
 * We have pcap_set_parser_debug() in libpcap; declare it (it's not declared
 * by any libpcap header, because it's a special hack, only available if
 * libpcap was configured to include it, and only intended for use by
 * libpcap developers trying to debug the parser for filter expressions).
 */
#ifdef _WIN32
__declspec(dllimport)
#else /* _WIN32 */
extern
#endif /* _WIN32 */
void pcap_set_parser_debug(int);
#elif defined(HAVE_PCAP_DEBUG) || defined(HAVE_YYDEBUG)
/*
 * We don't have pcap_set_parser_debug() in libpcap, but we do have
 * pcap_debug or yydebug.  Make a local version of pcap_set_parser_debug()
 * to set the flag, and define HAVE_PCAP_SET_PARSER_DEBUG.
 */
static void
pcap_set_parser_debug(int value)
{
#ifdef HAVE_PCAP_DEBUG
        extern int pcap_debug;

        pcap_debug = value;
#else /* HAVE_PCAP_DEBUG */
        extern int yydebug;

        yydebug = value;
#endif /* HAVE_PCAP_DEBUG */
}

#define HAVE_PCAP_SET_PARSER_DEBUG
#endif

#if defined(HAVE_PCAP_SET_OPTIMIZER_DEBUG)
/*
 * We have pcap_set_optimizer_debug() in libpcap; declare it (it's not declared
 * by any libpcap header, because it's a special hack, only available if
 * libpcap was configured to include it, and only intended for use by
 * libpcap developers trying to debug the optimizer for filter expressions).
 */
#ifdef _WIN32
__declspec(dllimport)
#else /* _WIN32 */
extern
#endif /* _WIN32 */
void pcap_set_optimizer_debug(int);
#endif

/* VARARGS */
static void
error(const char *fmt, ...)
{
        va_list ap;

        (void)fprintf(stderr, "%s: ", program_name);
        va_start(ap, fmt);
        (void)vfprintf(stderr, fmt, ap);
        va_end(ap);
        if (*fmt) {
                fmt += strlen(fmt);
                if (fmt[-1] != '\n')
                        (void)fputc('\n', stderr);
        }
        exit_tcpdump(1);
        /* NOTREACHED */
}

/* VARARGS */
static void
warning(const char *fmt, ...)
{
        va_list ap;

        (void)fprintf(stderr, "%s: WARNING: ", program_name);
        va_start(ap, fmt);
        (void)vfprintf(stderr, fmt, ap);
        va_end(ap);
        if (*fmt) {
                fmt += strlen(fmt);
                if (fmt[-1] != '\n')
                        (void)fputc('\n', stderr);
        }
}

static void
exit_tcpdump(int status)
{
        nd_cleanup();
        exit(status);
}

#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
static void
show_tstamp_types_and_exit(pcap_t *pc, const char *device)
{
        int n_tstamp_types;
        int *tstamp_types = 0;
        const char *tstamp_type_name;
        int i;

        n_tstamp_types = pcap_list_tstamp_types(pc, &tstamp_types);
        if (n_tstamp_types < 0)
                error("%s", pcap_geterr(pc));

        if (n_tstamp_types == 0) {
                fprintf(stderr, "Time stamp type cannot be set for %s\n",
                    device);
                exit_tcpdump(0);
        }
        fprintf(stderr, "Time stamp types for %s (use option -j to set):\n",
            device);
        for (i = 0; i < n_tstamp_types; i++) {
                tstamp_type_name = pcap_tstamp_type_val_to_name(tstamp_types[i]);
                if (tstamp_type_name != NULL) {
                        (void) fprintf(stderr, "  %s (%s)\n", tstamp_type_name,
                            pcap_tstamp_type_val_to_description(tstamp_types[i]));
                } else {
                        (void) fprintf(stderr, "  %d\n", tstamp_types[i]);
                }
        }
        pcap_free_tstamp_types(tstamp_types);
        exit_tcpdump(0);
}
#endif

static void
show_dlts_and_exit(pcap_t *pc, const char *device)
{
        int n_dlts, i;
        int *dlts = 0;
        const char *dlt_name;

        n_dlts = pcap_list_datalinks(pc, &dlts);
        if (n_dlts < 0)
                error("%s", pcap_geterr(pc));
        else if (n_dlts == 0 || !dlts)
                error("No data link types.");

        /*
         * If the interface is known to support monitor mode, indicate
         * whether these are the data link types available when not in
         * monitor mode, if -I wasn't specified, or when in monitor mode,
         * when -I was specified (the link-layer types available in
         * monitor mode might be different from the ones available when
         * not in monitor mode).
         */
        if (supports_monitor_mode)
                (void) fprintf(stderr, "Data link types for %s %s (use option -y to set):\n",
                    device,
                    Iflag ? "when in monitor mode" : "when not in monitor mode");
        else
                (void) fprintf(stderr, "Data link types for %s (use option -y to set):\n",
                    device);

        for (i = 0; i < n_dlts; i++) {
                dlt_name = pcap_datalink_val_to_name(dlts[i]);
                if (dlt_name != NULL) {
                        (void) fprintf(stderr, "  %s (%s)", dlt_name,
                            pcap_datalink_val_to_description(dlts[i]));

                        /*
                         * OK, does tcpdump handle that type?
                         */
                        if (!has_printer(dlts[i]))
                                (void) fprintf(stderr, " (printing not supported)");
                        fprintf(stderr, "\n");
                } else {
                        (void) fprintf(stderr, "  DLT %d (printing not supported)\n",
                            dlts[i]);
                }
        }
#ifdef HAVE_PCAP_FREE_DATALINKS
        pcap_free_datalinks(dlts);
#endif
        exit_tcpdump(0);
}

#ifdef HAVE_PCAP_FINDALLDEVS
static void
show_devices_and_exit (void)
{
        pcap_if_t *dev, *devlist;
        char ebuf[PCAP_ERRBUF_SIZE];
        int i;

        if (pcap_findalldevs(&devlist, ebuf) < 0)
                error("%s", ebuf);
        for (i = 0, dev = devlist; dev != NULL; i++, dev = dev->next) {
                printf("%d.%s", i+1, dev->name);
                if (dev->description != NULL)
                        printf(" (%s)", dev->description);
                if (dev->flags != 0)
                        printf(" [%s]", bittok2str(status_flags, "none", dev->flags));
                printf("\n");
        }
        pcap_freealldevs(devlist);
        exit_tcpdump(0);
}
#endif /* HAVE_PCAP_FINDALLDEVS */

/*
 * Short options.
 *
 * Note that there we use all letters for short options except for g, k,
 * o, and P, and those are used by other versions of tcpdump, and we should
 * only use them for the same purposes that the other versions of tcpdump
 * use them:
 *
 * OS X tcpdump uses -g to force non--v output for IP to be on one
 * line, making it more "g"repable;
 *
 * OS X tcpdump uses -k tospecify that packet comments in pcap-ng files
 * should be printed;
 *
 * OpenBSD tcpdump uses -o to indicate that OS fingerprinting should be done
 * for hosts sending TCP SYN packets;
 *
 * OS X tcpdump uses -P to indicate that -w should write pcap-ng rather
 * than pcap files.
 *
 * OS X tcpdump also uses -Q to specify expressions that match packet
 * metadata, including but not limited to the packet direction.
 * The expression syntax is different from a simple "in|out|inout",
 * and those expressions aren't accepted by OS X tcpdump, but the
 * equivalents would be "in" = "dir=in", "out" = "dir=out", and
 * "inout" = "dir=in or dir=out", and the parser could conceivably
 * special-case "in", "out", and "inout" as expressions for backwards
 * compatibility, so all is not (yet) lost.
 */

/*
 * Set up flags that might or might not be supported depending on the
 * version of libpcap we're using.
 */
#if defined(HAVE_PCAP_CREATE) || defined(_WIN32)
#define B_FLAG          "B:"
#define B_FLAG_USAGE    " [ -B size ]"
#else /* defined(HAVE_PCAP_CREATE) || defined(_WIN32) */
#define B_FLAG
#define B_FLAG_USAGE
#endif /* defined(HAVE_PCAP_CREATE) || defined(_WIN32) */

#ifdef HAVE_PCAP_CREATE
#define I_FLAG          "I"
#else /* HAVE_PCAP_CREATE */
#define I_FLAG
#endif /* HAVE_PCAP_CREATE */

#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
#define j_FLAG          "j:"
#define j_FLAG_USAGE    " [ -j tstamptype ]"
#define J_FLAG          "J"
#else /* PCAP_ERROR_TSTAMP_TYPE_NOTSUP */
#define j_FLAG
#define j_FLAG_USAGE
#define J_FLAG
#endif /* PCAP_ERROR_TSTAMP_TYPE_NOTSUP */

#ifdef HAVE_PCAP_FINDALLDEVS
#define D_FLAG  "D"
#else
#define D_FLAG
#endif

#ifdef HAVE_PCAP_DUMP_FLUSH
#define U_FLAG  "U"
#else
#define U_FLAG
#endif

#ifdef HAVE_PCAP_SETDIRECTION
#define Q_FLAG "Q:"
#else
#define Q_FLAG
#endif

#define SHORTOPTS "aAb" B_FLAG "c:C:d" D_FLAG "eE:fF:G:hHi:" I_FLAG j_FLAG J_FLAG "KlLm:M:nNOpq" Q_FLAG "r:s:StT:u" U_FLAG "vV:w:W:xXy:Yz:Z:#"

/*
 * Long options.
 *
 * We do not currently have long options corresponding to all short
 * options; we should probably pick appropriate option names for them.
 *
 * However, the short options where the number of times the option is
 * specified matters, such as -v and -d and -t, should probably not
 * just map to a long option, as saying
 *
 *  tcpdump --verbose --verbose
 *
 * doesn't make sense; it should be --verbosity={N} or something such
 * as that.
 *
 * For long options with no corresponding short options, we define values
 * outside the range of ASCII graphic characters, make that the last
 * component of the entry for the long option, and have a case for that
 * option in the switch statement.
 */
#define OPTION_VERSION          128
#define OPTION_TSTAMP_PRECISION 129
#define OPTION_IMMEDIATE_MODE   130

static const struct option longopts[] = {
#if defined(HAVE_PCAP_CREATE) || defined(_WIN32)
        { "buffer-size", required_argument, NULL, 'B' },
#endif
        { "list-interfaces", no_argument, NULL, 'D' },
        { "help", no_argument, NULL, 'h' },
        { "interface", required_argument, NULL, 'i' },
#ifdef HAVE_PCAP_CREATE
        { "monitor-mode", no_argument, NULL, 'I' },
#endif
#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
        { "time-stamp-type", required_argument, NULL, 'j' },
        { "list-time-stamp-types", no_argument, NULL, 'J' },
#endif
#ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
        { "time-stamp-precision", required_argument, NULL, OPTION_TSTAMP_PRECISION},
#endif
        { "dont-verify-checksums", no_argument, NULL, 'K' },
        { "list-data-link-types", no_argument, NULL, 'L' },
        { "no-optimize", no_argument, NULL, 'O' },
        { "no-promiscuous-mode", no_argument, NULL, 'p' },
#ifdef HAVE_PCAP_SETDIRECTION
        { "direction", required_argument, NULL, 'Q' },
#endif
        { "snapshot-length", required_argument, NULL, 's' },
        { "absolute-tcp-sequence-numbers", no_argument, NULL, 'S' },
#ifdef HAVE_PCAP_DUMP_FLUSH
        { "packet-buffered", no_argument, NULL, 'U' },
#endif
        { "linktype", required_argument, NULL, 'y' },
#ifdef HAVE_PCAP_SET_IMMEDIATE_MODE
        { "immediate-mode", no_argument, NULL, OPTION_IMMEDIATE_MODE },
#endif
#ifdef HAVE_PCAP_SET_PARSER_DEBUG
        { "debug-filter-parser", no_argument, NULL, 'Y' },
#endif
        { "relinquish-privileges", required_argument, NULL, 'Z' },
        { "number", no_argument, NULL, '#' },
        { "version", no_argument, NULL, OPTION_VERSION },
        { NULL, 0, NULL, 0 }
};

#ifndef _WIN32
/* Drop root privileges and chroot if necessary */
static void
droproot(const char *username, const char *chroot_dir)
{
        struct passwd *pw = NULL;

        if (chroot_dir && !username) {
                fprintf(stderr, "%s: Chroot without dropping root is insecure\n",
                        program_name);
                exit_tcpdump(1);
        }

        pw = getpwnam(username);
        if (pw) {
                if (chroot_dir) {
                        if (chroot(chroot_dir) != 0 || chdir ("/") != 0) {
                                fprintf(stderr, "%s: Couldn't chroot/chdir to '%.64s': %s\n",
                                        program_name, chroot_dir, pcap_strerror(errno));
                                exit_tcpdump(1);
                        }
                }
#ifdef HAVE_LIBCAP_NG
                {
                        int ret = capng_change_id(pw->pw_uid, pw->pw_gid, CAPNG_NO_FLAG);
                        if (ret < 0) {
                                fprintf(stderr, "error : ret %d\n", ret);
                        } else {
                                fprintf(stderr, "dropped privs to %s\n", username);
                        }
                }
#else
                if (initgroups(pw->pw_name, pw->pw_gid) != 0 ||
                    setgid(pw->pw_gid) != 0 || setuid(pw->pw_uid) != 0) {
                        fprintf(stderr, "%s: Couldn't change to '%.32s' uid=%lu gid=%lu: %s\n",
                                program_name, username,
                                (unsigned long)pw->pw_uid,
                                (unsigned long)pw->pw_gid,
                                pcap_strerror(errno));
                        exit_tcpdump(1);
                }
                else {
                        fprintf(stderr, "dropped privs to %s\n", username);
                }
#endif /* HAVE_LIBCAP_NG */
        }
        else {
                fprintf(stderr, "%s: Couldn't find user '%.32s'\n",
                        program_name, username);
                exit_tcpdump(1);
        }
#ifdef HAVE_LIBCAP_NG
        /* We don't need CAP_SETUID and CAP_SETGID any more. */
        capng_updatev(
                CAPNG_DROP,
                CAPNG_EFFECTIVE | CAPNG_PERMITTED,
                CAP_SETUID,
                CAP_SETGID,
                -1);
        capng_apply(CAPNG_SELECT_BOTH);
#endif /* HAVE_LIBCAP_NG */

}
#endif /* _WIN32 */

static int
getWflagChars(int x)
{
        int c = 0;

        x -= 1;
        while (x > 0) {
                c += 1;
                x /= 10;
        }

        return c;
}


static void
MakeFilename(char *buffer, char *orig_name, int cnt, int max_chars)
{
        char *filename = malloc(PATH_MAX + 1);
        if (filename == NULL)
            error("Makefilename: malloc");

        /* Process with strftime if Gflag is set. */
        if (Gflag != 0) {
          struct tm *local_tm;

          /* Convert Gflag_time to a usable format */
          if ((local_tm = localtime(&Gflag_time)) == NULL) {
                  error("MakeTimedFilename: localtime");
          }

          /* There's no good way to detect an error in strftime since a return
           * value of 0 isn't necessarily failure.
           */
          strftime(filename, PATH_MAX, orig_name, local_tm);
        } else {
          strncpy(filename, orig_name, PATH_MAX);
        }

        if (cnt == 0 && max_chars == 0)
                strncpy(buffer, filename, PATH_MAX + 1);
        else
                if (snprintf(buffer, PATH_MAX + 1, "%s%0*d", filename, max_chars, cnt) > PATH_MAX)
                  /* Report an error if the filename is too large */
                  error("too many output files or filename is too long (> %d)", PATH_MAX);
        free(filename);
}

static char *
get_next_file(FILE *VFile, char *ptr)
{
        char *ret;

        ret = fgets(ptr, PATH_MAX, VFile);
        if (!ret)
                return NULL;

        if (ptr[strlen(ptr) - 1] == '\n')
                ptr[strlen(ptr) - 1] = '\0';

        return ret;
}

#ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
static int
tstamp_precision_from_string(const char *precision)
{
        if (strncmp(precision, "nano", strlen("nano")) == 0)
                return PCAP_TSTAMP_PRECISION_NANO;

        if (strncmp(precision, "micro", strlen("micro")) == 0)
                return PCAP_TSTAMP_PRECISION_MICRO;

        return -EINVAL;
}

static const char *
tstamp_precision_to_string(int precision)
{
        switch (precision) {

        case PCAP_TSTAMP_PRECISION_MICRO:
                return "micro";

        case PCAP_TSTAMP_PRECISION_NANO:
                return "nano";

        default:
                return "unknown";
        }
}
#endif

#ifdef HAVE_CAPSICUM
/*
 * Ensure that, on a dump file's descriptor, we have all the rights
 * necessary to make the standard I/O library work with an fdopen()ed
 * FILE * from that descriptor.
 *
 * A long time ago, in a galaxy far far away, AT&T decided that, instead
 * of providing separate APIs for getting and setting the FD_ flags on a
 * descriptor, getting and setting the O_ flags on a descriptor, and
 * locking files, they'd throw them all into a kitchen-sink fcntl() call
 * along the lines of ioctl(), the fact that ioctl() operations are
 * largely specific to particular character devices but fcntl() operations
 * are either generic to all descriptors or generic to all descriptors for
 * regular files nonwithstanding.
 *
 * The Capsicum people decided that fine-grained control of descriptor
 * operations was required, so that you need to grant permission for
 * reading, writing, seeking, and fcntl-ing.  The latter, courtesy of
 * AT&T's decision, means that "fcntl-ing" isn't a thing, but a motley
 * collection of things, so there are *individual* fcntls for which
 * permission needs to be granted.
 *
 * The FreeBSD standard I/O people implemented some optimizations that
 * requires that the standard I/O routines be able to determine whether
 * the descriptor for the FILE * is open append-only or not; as that
 * descriptor could have come from an open() rather than an fopen(),
 * that requires that it be able to do an F_GETFL fcntl() to read
 * the O_ flags.
 *
 * Tcpdump uses ftell() to determine how much data has been written
 * to a file in order to, when used with -C, determine when it's time
 * to rotate capture files.  ftell() therefore needs to do an lseek()
 * to find out the file offset and must, thanks to the aforementioned
 * optimization, also know whether the descriptor is open append-only
 * or not.
 *
 * The net result of all the above is that we need to grant CAP_SEEK,
 * CAP_WRITE, and CAP_FCNTL with the CAP_FCNTL_GETFL subcapability.
 *
 * Perhaps this is the universe's way of saying that either
 *
 *      1) there needs to be an fopenat() call and a pcap_dump_openat() call
 *         using it, so that Capsicum-capable tcpdump wouldn't need to do
 *         an fdopen()
 *
 * or
 *
 *      2) there needs to be a cap_fdopen() call in the FreeBSD standard
 *         I/O library that knows what rights are needed by the standard
 *         I/O library, based on the open mode, and assigns them, perhaps
 *         with an additional argument indicating, for example, whether
 *         seeking should be allowed, so that tcpdump doesn't need to know
 *         what the standard I/O library happens to require this week.
 */
static void
set_dumper_capsicum_rights(pcap_dumper_t *p)
{
        int fd = fileno(pcap_dump_file(p));
        cap_rights_t rights;

        cap_rights_init(&rights, CAP_SEEK, CAP_WRITE, CAP_FCNTL);
        if (cap_rights_limit(fd, &rights) < 0 && errno != ENOSYS) {
                error("unable to limit dump descriptor");
        }
        if (cap_fcntls_limit(fd, CAP_FCNTL_GETFL) < 0 && errno != ENOSYS) {
                error("unable to limit dump descriptor fcntls");
        }
}
#endif

/*
 * Copy arg vector into a new buffer, concatenating arguments with spaces.
 */
static char *
copy_argv(register char **argv)
{
        register char **p;
        register u_int len = 0;
        char *buf;
        char *src, *dst;

        p = argv;
        if (*p == NULL)
                return 0;

        while (*p)
                len += strlen(*p++) + 1;

        buf = (char *)malloc(len);
        if (buf == NULL)
                error("copy_argv: malloc");

        p = argv;
        dst = buf;
        while ((src = *p++) != NULL) {
                while ((*dst++ = *src++) != '\0')
                        ;
                dst[-1] = ' ';
        }
        dst[-1] = '\0';

        return buf;
}

/*
 * On Windows, we need to open the file in binary mode, so that
 * we get all the bytes specified by the size we get from "fstat()".
 * On UNIX, that's not necessary.  O_BINARY is defined on Windows;
 * we define it as 0 if it's not defined, so it does nothing.
 */
#ifndef O_BINARY
#define O_BINARY        0
#endif

static char *
read_infile(char *fname)
{
        register int i, fd, cc;
        register char *cp;
        struct stat buf;

        fd = open(fname, O_RDONLY|O_BINARY);
        if (fd < 0)
                error("can't open %s: %s", fname, pcap_strerror(errno));

        if (fstat(fd, &buf) < 0)
                error("can't stat %s: %s", fname, pcap_strerror(errno));

        cp = malloc((u_int)buf.st_size + 1);
        if (cp == NULL)
                error("malloc(%d) for %s: %s", (u_int)buf.st_size + 1,
                        fname, pcap_strerror(errno));
        cc = read(fd, cp, (u_int)buf.st_size);
        if (cc < 0)
                error("read %s: %s", fname, pcap_strerror(errno));
        if (cc != buf.st_size)
                error("short read %s (%d != %d)", fname, cc, (int)buf.st_size);

        close(fd);
        /* replace "# comment" with spaces */
        for (i = 0; i < cc; i++) {
                if (cp[i] == '#')
                        while (i < cc && cp[i] != '\n')
                                cp[i++] = ' ';
        }
        cp[cc] = '\0';
        return (cp);
}

#ifdef HAVE_PCAP_FINDALLDEVS
static long
parse_interface_number(const char *device)
{
        long devnum;
        char *end;

        devnum = strtol(device, &end, 10);
        if (device != end && *end == '\0') {
                /*
                 * It's all-numeric, but is it a valid number?
                 */
                if (devnum <= 0) {
                        /*
                         * No, it's not an ordinal.
                         */
                        error("Invalid adapter index");
                }
                return (devnum);
        } else {
                /*
                 * It's not all-numeric; return -1, so our caller
                 * knows that.
                 */
                return (-1);
        }
}

static char *
find_interface_by_number(long devnum)
{
        pcap_if_t *dev, *devlist;
        long i;
        char ebuf[PCAP_ERRBUF_SIZE];
        char *device;

        if (pcap_findalldevs(&devlist, ebuf) < 0)
                error("%s", ebuf);
        /*
         * Look for the devnum-th entry in the list of devices (1-based).
         */
        for (i = 0, dev = devlist; i < devnum-1 && dev != NULL;
            i++, dev = dev->next)
                ;
        if (dev == NULL)
                error("Invalid adapter index");
        device = strdup(dev->name);
        pcap_freealldevs(devlist);
        return (device);
}
#endif

static pcap_t *
open_interface(const char *device, netdissect_options *ndo, char *ebuf)
{
        pcap_t *pc;
#ifdef HAVE_PCAP_CREATE
        int status;
        char *cp;
#endif

#ifdef HAVE_PCAP_CREATE
        pc = pcap_create(device, ebuf);
        if (pc == NULL) {
                /*
                 * If this failed with "No such device", that means
                 * the interface doesn't exist; return NULL, so that
                 * the caller can see whether the device name is
                 * actually an interface index.
                 */
                if (strstr(ebuf, "No such device") != NULL)
                        return (NULL);
                error("%s", ebuf);
        }
#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
        if (Jflag)
                show_tstamp_types_and_exit(pc, device);
#endif
#ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
        status = pcap_set_tstamp_precision(pc, ndo->ndo_tstamp_precision);
        if (status != 0)
                error("%s: Can't set %ssecond time stamp precision: %s",
                        device,
                        tstamp_precision_to_string(ndo->ndo_tstamp_precision),
                        pcap_statustostr(status));
#endif

#ifdef HAVE_PCAP_SET_IMMEDIATE_MODE
        if (immediate_mode) {
                status = pcap_set_immediate_mode(pc, 1);
                if (status != 0)
                        error("%s: Can't set immediate mode: %s",
                        device,
                        pcap_statustostr(status));
        }
#endif
        /*
         * Is this an interface that supports monitor mode?
         */
        if (pcap_can_set_rfmon(pc) == 1)
                supports_monitor_mode = 1;
        else
                supports_monitor_mode = 0;
        status = pcap_set_snaplen(pc, ndo->ndo_snaplen);
        if (status != 0)
                error("%s: Can't set snapshot length: %s",
                    device, pcap_statustostr(status));
        status = pcap_set_promisc(pc, !pflag);
        if (status != 0)
                error("%s: Can't set promiscuous mode: %s",
                    device, pcap_statustostr(status));
        if (Iflag) {
                status = pcap_set_rfmon(pc, 1);
                if (status != 0)
                        error("%s: Can't set monitor mode: %s",
                            device, pcap_statustostr(status));
        }
        status = pcap_set_timeout(pc, 1000);
        if (status != 0)
                error("%s: pcap_set_timeout failed: %s",
                    device, pcap_statustostr(status));
        if (Bflag != 0) {
                status = pcap_set_buffer_size(pc, Bflag);
                if (status != 0)
                        error("%s: Can't set buffer size: %s",
                            device, pcap_statustostr(status));
        }
#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
        if (jflag != -1) {
                status = pcap_set_tstamp_type(pc, jflag);
                if (status < 0)
                        error("%s: Can't set time stamp type: %s",
                              device, pcap_statustostr(status));
        }
#endif
        status = pcap_activate(pc);
        if (status < 0) {
                /*
                 * pcap_activate() failed.
                 */
                cp = pcap_geterr(pc);
                if (status == PCAP_ERROR)
                        error("%s", cp);
                else if (status == PCAP_ERROR_NO_SUCH_DEVICE) {
                        /*
                         * Return an error for our caller to handle.
                         */
                        pcap_close(pc);
                        snprintf(ebuf, PCAP_ERRBUF_SIZE, "%s: %s\n(%s)",
                            device, pcap_statustostr(status), cp);
                        return (NULL);
                } else if (status == PCAP_ERROR_PERM_DENIED && *cp != '\0')
                        error("%s: %s\n(%s)", device,
                            pcap_statustostr(status), cp);
                else
                        error("%s: %s", device,
                            pcap_statustostr(status));
        } else if (status > 0) {
                /*
                 * pcap_activate() succeeded, but it's warning us
                 * of a problem it had.
                 */
                cp = pcap_geterr(pc);
                if (status == PCAP_WARNING)
                        warning("%s", cp);
                else if (status == PCAP_WARNING_PROMISC_NOTSUP &&
                         *cp != '\0')
                        warning("%s: %s\n(%s)", device,
                            pcap_statustostr(status), cp);
                else
                        warning("%s: %s", device,
                            pcap_statustostr(status));
        }
#ifdef HAVE_PCAP_SETDIRECTION
        if (Qflag != -1) {
                status = pcap_setdirection(pc, Qflag);
                if (status != 0)
                        error("%s: pcap_setdirection() failed: %s",
                              device,  pcap_geterr(pc));
                }
#endif /* HAVE_PCAP_SETDIRECTION */
#else /* HAVE_PCAP_CREATE */
        *ebuf = '\0';
        pc = pcap_open_live(device, ndo->ndo_snaplen, !pflag, 1000, ebuf);
        if (pc == NULL) {
                /*
                 * If this failed with "No such device", that means
                 * the interface doesn't exist; return NULL, so that
                 * the caller can see whether the device name is
                 * actually an interface index.
                 */
                if (strstr(ebuf, "No such device") != NULL)
                        return (NULL);
                error("%s", ebuf);
        }
        if (*ebuf)
                warning("%s", ebuf);
#endif /* HAVE_PCAP_CREATE */

        return (pc);
}

int
main(int argc, char **argv)
{
        register int cnt, op, i;
        bpf_u_int32 localnet =0 , netmask = 0;
        int timezone_offset = 0;
        register char *cp, *infile, *cmdbuf, *device, *RFileName, *VFileName, *WFileName;
        pcap_handler callback;
        int dlt;
        const char *dlt_name;
        struct bpf_program fcode;
#ifndef _WIN32
        RETSIGTYPE (*oldhandler)(int);
#endif
        struct dump_info dumpinfo;
        u_char *pcap_userdata;
        char ebuf[PCAP_ERRBUF_SIZE];
        char VFileLine[PATH_MAX + 1];
        char *username = NULL;
        char *chroot_dir = NULL;
        char *ret = NULL;
        char *end;
#ifdef HAVE_PCAP_FINDALLDEVS
        pcap_if_t *devlist;
        long devnum;
#endif
        int status;
        FILE *VFile;
#ifdef HAVE_CAPSICUM
        cap_rights_t rights;
        int cansandbox;
#endif  /* HAVE_CAPSICUM */
        int Oflag = 1;                  /* run filter code optimizer */
        int yflag_dlt = -1;
        const char *yflag_dlt_name = NULL;

        netdissect_options Ndo;
        netdissect_options *ndo = &Ndo;

        /*
         * Initialize the netdissect code.
         */
        if (nd_init(ebuf, sizeof ebuf) == -1)
                error("%s", ebuf);

        memset(ndo, 0, sizeof(*ndo));
        ndo_set_function_pointers(ndo);
        ndo->ndo_snaplen = DEFAULT_SNAPLEN;

        cnt = -1;
        device = NULL;
        infile = NULL;
        RFileName = NULL;
        VFileName = NULL;
        VFile = NULL;
        WFileName = NULL;
        dlt = -1;
        if ((cp = strrchr(argv[0], '/')) != NULL)
                ndo->program_name = program_name = cp + 1;
        else
                ndo->program_name = program_name = argv[0];

#ifdef _WIN32
        if (pcap_wsockinit() != 0)
                error("Attempting to initialize Winsock failed");
#endif /* _WIN32 */

        /*
         * On platforms where the CPU doesn't support unaligned loads,
         * force unaligned accesses to abort with SIGBUS, rather than
         * being fixed up (slowly) by the OS kernel; on those platforms,
         * misaligned accesses are bugs, and we want tcpdump to crash so
         * that the bugs are reported.
         */
        if (abort_on_misalignment(ebuf, sizeof(ebuf)) < 0)
                error("%s", ebuf);

        while (
            (op = getopt_long(argc, argv, SHORTOPTS, longopts, NULL)) != -1)
                switch (op) {

                case 'a':
                        /* compatibility for old -a */
                        break;

                case 'A':
                        ++ndo->ndo_Aflag;
                        break;

                case 'b':
                        ++ndo->ndo_bflag;
                        break;

#if defined(HAVE_PCAP_CREATE) || defined(_WIN32)
                case 'B':
                        Bflag = atoi(optarg)*1024;
                        if (Bflag <= 0)
                                error("invalid packet buffer size %s", optarg);
                        break;
#endif /* defined(HAVE_PCAP_CREATE) || defined(_WIN32) */

                case 'c':
                        cnt = atoi(optarg);
                        if (cnt <= 0)
                                error("invalid packet count %s", optarg);
                        break;

                case 'C':
                        Cflag = atoi(optarg) * 1000000;
                        if (Cflag <= 0)
                                error("invalid file size %s", optarg);
                        break;

                case 'd':
                        ++dflag;
                        break;

                case 'D':
                        Dflag++;
                        break;

                case 'L':
                        Lflag++;
                        break;

                case 'e':
                        ++ndo->ndo_eflag;
                        break;

                case 'E':
#ifndef HAVE_LIBCRYPTO
                        warning("crypto code not compiled in");
#endif
                        ndo->ndo_espsecret = optarg;
                        break;

                case 'f':
                        ++ndo->ndo_fflag;
                        break;

                case 'F':
                        infile = optarg;
                        break;

                case 'G':
                        Gflag = atoi(optarg);
                        if (Gflag < 0)
                                error("invalid number of seconds %s", optarg);

                        /* We will create one file initially. */
                        Gflag_count = 0;

                        /* Grab the current time for rotation use. */
                        if ((Gflag_time = time(NULL)) == (time_t)-1) {
                                error("main: can't get current time: %s",
                                    pcap_strerror(errno));
                        }
                        break;

                case 'h':
                        print_usage();
                        exit_tcpdump(0);
                        break;

                case 'H':
                        ++ndo->ndo_Hflag;
                        break;

                case 'i':
                        device = optarg;
                        break;

#ifdef HAVE_PCAP_CREATE
                case 'I':
                        ++Iflag;
                        break;
#endif /* HAVE_PCAP_CREATE */

#ifdef HAVE_PCAP_SET_TSTAMP_TYPE
                case 'j':
                        jflag = pcap_tstamp_type_name_to_val(optarg);
                        if (jflag < 0)
                                error("invalid time stamp type %s", optarg);
                        break;

                case 'J':
                        Jflag++;
                        break;
#endif

                case 'l':
#ifdef _WIN32
                        /*
                         * _IOLBF is the same as _IOFBF in Microsoft's C
                         * libraries; the only alternative they offer
                         * is _IONBF.
                         *
                         * XXX - this should really be checking for MSVC++,
                         * not _WIN32, if, for example, MinGW has its own
                         * C library that is more UNIX-compatible.
                         */
                        setvbuf(stdout, NULL, _IONBF, 0);
#else /* _WIN32 */
#ifdef HAVE_SETLINEBUF
                        setlinebuf(stdout);
#else
                        setvbuf(stdout, NULL, _IOLBF, 0);
#endif
#endif /* _WIN32 */
                        break;

                case 'K':
                        ++ndo->ndo_Kflag;
                        break;

                case 'm':
                        if (nd_have_smi_support()) {
                                if (nd_load_smi_module(optarg, ebuf, sizeof ebuf) == -1)
                                        error("%s", ebuf);
                        } else {
                                (void)fprintf(stderr, "%s: ignoring option `-m %s' ",
                                              program_name, optarg);
                                (void)fprintf(stderr, "(no libsmi support)\n");
                        }
                        break;

                case 'M':
                        /* TCP-MD5 shared secret */
#ifndef HAVE_LIBCRYPTO
                        warning("crypto code not compiled in");
#endif
                        ndo->ndo_sigsecret = optarg;
                        break;

                case 'n':
                        ++ndo->ndo_nflag;
                        break;

                case 'N':
                        ++ndo->ndo_Nflag;
                        break;

                case 'O':
                        Oflag = 0;
                        break;

                case 'p':
                        ++pflag;
                        break;

                case 'q':
                        ++ndo->ndo_qflag;
                        ++ndo->ndo_suppress_default_print;
                        break;

#ifdef HAVE_PCAP_SETDIRECTION
                case 'Q':
                        if (ascii_strcasecmp(optarg, "in") == 0)
                                Qflag = PCAP_D_IN;
                        else if (ascii_strcasecmp(optarg, "out") == 0)
                                Qflag = PCAP_D_OUT;
                        else if (ascii_strcasecmp(optarg, "inout") == 0)
                                Qflag = PCAP_D_INOUT;
                        else
                                error("unknown capture direction `%s'", optarg);
                        break;
#endif /* HAVE_PCAP_SETDIRECTION */

                case 'r':
                        RFileName = optarg;
                        break;

                case 's':
                        ndo->ndo_snaplen = strtol(optarg, &end, 0);
                        if (optarg == end || *end != '\0'
                            || ndo->ndo_snaplen < 0 || ndo->ndo_snaplen > MAXIMUM_SNAPLEN)
                                error("invalid snaplen %s", optarg);
                        else if (ndo->ndo_snaplen == 0)
                                ndo->ndo_snaplen = MAXIMUM_SNAPLEN;
                        break;

                case 'S':
                        ++ndo->ndo_Sflag;
                        break;

                case 't':
                        ++ndo->ndo_tflag;
                        break;

                case 'T':
                        if (ascii_strcasecmp(optarg, "vat") == 0)
                                ndo->ndo_packettype = PT_VAT;
                        else if (ascii_strcasecmp(optarg, "wb") == 0)
                                ndo->ndo_packettype = PT_WB;
                        else if (ascii_strcasecmp(optarg, "rpc") == 0)
                                ndo->ndo_packettype = PT_RPC;
                        else if (ascii_strcasecmp(optarg, "rtp") == 0)
                                ndo->ndo_packettype = PT_RTP;
                        else if (ascii_strcasecmp(optarg, "rtcp") == 0)
                                ndo->ndo_packettype = PT_RTCP;
                        else if (ascii_strcasecmp(optarg, "snmp") == 0)
                                ndo->ndo_packettype = PT_SNMP;
                        else if (ascii_strcasecmp(optarg, "cnfp") == 0)
                                ndo->ndo_packettype = PT_CNFP;
                        else if (ascii_strcasecmp(optarg, "tftp") == 0)
                                ndo->ndo_packettype = PT_TFTP;
                        else if (ascii_strcasecmp(optarg, "aodv") == 0)
                                ndo->ndo_packettype = PT_AODV;
                        else if (ascii_strcasecmp(optarg, "carp") == 0)
                                ndo->ndo_packettype = PT_CARP;
                        else if (ascii_strcasecmp(optarg, "radius") == 0)
                                ndo->ndo_packettype = PT_RADIUS;
                        else if (ascii_strcasecmp(optarg, "zmtp1") == 0)
                                ndo->ndo_packettype = PT_ZMTP1;
                        else if (ascii_strcasecmp(optarg, "vxlan") == 0)
                                ndo->ndo_packettype = PT_VXLAN;
                        else if (ascii_strcasecmp(optarg, "pgm") == 0)
                                ndo->ndo_packettype = PT_PGM;
                        else if (ascii_strcasecmp(optarg, "pgm_zmtp1") == 0)
                                ndo->ndo_packettype = PT_PGM_ZMTP1;
                        else if (ascii_strcasecmp(optarg, "lmp") == 0)
                                ndo->ndo_packettype = PT_LMP;
                        else if (ascii_strcasecmp(optarg, "resp") == 0)
                                ndo->ndo_packettype = PT_RESP;
                        else
                                error("unknown packet type `%s'", optarg);
                        break;

                case 'u':
                        ++ndo->ndo_uflag;
                        break;

#ifdef HAVE_PCAP_DUMP_FLUSH
                case 'U':
                        ++Uflag;
                        break;
#endif

                case 'v':
                        ++ndo->ndo_vflag;
                        break;

                case 'V':
                        VFileName = optarg;
                        break;

                case 'w':
                        WFileName = optarg;
                        break;

                case 'W':
                        Wflag = atoi(optarg);
                        if (Wflag <= 0)
                                error("invalid number of output files %s", optarg);
                        WflagChars = getWflagChars(Wflag);
                        break;

                case 'x':
                        ++ndo->ndo_xflag;
                        ++ndo->ndo_suppress_default_print;
                        break;

                case 'X':
                        ++ndo->ndo_Xflag;
                        ++ndo->ndo_suppress_default_print;
                        break;

                case 'y':
                        yflag_dlt_name = optarg;
                        yflag_dlt =
                                pcap_datalink_name_to_val(yflag_dlt_name);
                        if (yflag_dlt < 0)
                                error("invalid data link type %s", yflag_dlt_name);
                        break;

#ifdef HAVE_PCAP_SET_PARSER_DEBUG
                case 'Y':
                        {
                        /* Undocumented flag */
                        pcap_set_parser_debug(1);
                        }
                        break;
#endif
                case 'z':
                        zflag = optarg;
                        break;

                case 'Z':
                        username = optarg;
                        break;

                case '#':
                        ndo->ndo_packet_number = 1;
                        break;

                case OPTION_VERSION:
                        print_version();
                        exit_tcpdump(0);
                        break;

#ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
                case OPTION_TSTAMP_PRECISION:
                        ndo->ndo_tstamp_precision = tstamp_precision_from_string(optarg);
                        if (ndo->ndo_tstamp_precision < 0)
                                error("unsupported time stamp precision");
                        break;
#endif

#ifdef HAVE_PCAP_SET_IMMEDIATE_MODE
                case OPTION_IMMEDIATE_MODE:
                        immediate_mode = 1;
                        break;
#endif

                default:
                        print_usage();
                        exit_tcpdump(1);
                        /* NOTREACHED */
                }

#ifdef HAVE_PCAP_FINDALLDEVS
        if (Dflag)
                show_devices_and_exit();
#endif

        switch (ndo->ndo_tflag) {

        case 0: /* Default */
        case 4: /* Default + Date*/
                timezone_offset = gmt2local(0);
                break;

        case 1: /* No time stamp */
        case 2: /* Unix timeval style */
        case 3: /* Microseconds since previous packet */
        case 5: /* Microseconds since first packet */
                break;

        default: /* Not supported */
                error("only -t, -tt, -ttt, -tttt and -ttttt are supported");
                break;
        }

        if (ndo->ndo_fflag != 0 && (VFileName != NULL || RFileName != NULL))
                error("-f can not be used with -V or -r");

        if (VFileName != NULL && RFileName != NULL)
                error("-V and -r are mutually exclusive.");

#ifdef HAVE_PCAP_SET_IMMEDIATE_MODE
        /*
         * If we're printing dissected packets to the standard output
         * rather than saving raw packets to a file, and the standard
         * output is a terminal, use immediate mode, as the user's
         * probably expecting to see packets pop up immediately.
         */
        if (WFileName == NULL && isatty(1))
                immediate_mode = 1;
#endif

#ifdef WITH_CHROOT
        /* if run as root, prepare for chrooting */
        if (getuid() == 0 || geteuid() == 0) {
                /* future extensibility for cmd-line arguments */
                if (!chroot_dir)
                        chroot_dir = WITH_CHROOT;
        }
#endif

#ifdef WITH_USER
        /* if run as root, prepare for dropping root privileges */
        if (getuid() == 0 || geteuid() == 0) {
                /* Run with '-Z root' to restore old behaviour */
                if (!username)
                        username = WITH_USER;
        }
#endif

        if (RFileName != NULL || VFileName != NULL) {
                /*
                 * If RFileName is non-null, it's the pathname of a
                 * savefile to read.  If VFileName is non-null, it's
                 * the pathname of a file containing a list of pathnames
                 * (one per line) of savefiles to read.
                 *
                 * In either case, we're reading a savefile, not doing
                 * a live capture.
                 */
#ifndef _WIN32
                /*
                 * We don't need network access, so relinquish any set-UID
                 * or set-GID privileges we have (if any).
                 *
                 * We do *not* want set-UID privileges when opening a
                 * trace file, as that might let the user read other
                 * people's trace files (especially if we're set-UID
                 * root).
                 */
                if (setgid(getgid()) != 0 || setuid(getuid()) != 0 )
                        fprintf(stderr, "Warning: setgid/setuid failed !\n");
#endif /* _WIN32 */
                if (VFileName != NULL) {
                        if (VFileName[0] == '-' && VFileName[1] == '\0')
                                VFile = stdin;
                        else
                                VFile = fopen(VFileName, "r");

                        if (VFile == NULL)
                                error("Unable to open file: %s\n", pcap_strerror(errno));

                        ret = get_next_file(VFile, VFileLine);
                        if (!ret)
                                error("Nothing in %s\n", VFileName);
                        RFileName = VFileLine;
                }

#ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
                pd = pcap_open_offline_with_tstamp_precision(RFileName,
                    ndo->ndo_tstamp_precision, ebuf);
#else
                pd = pcap_open_offline(RFileName, ebuf);
#endif

                if (pd == NULL)
                        error("%s", ebuf);
#ifdef HAVE_CAPSICUM
                cap_rights_init(&rights, CAP_READ);
                if (cap_rights_limit(fileno(pcap_file(pd)), &rights) < 0 &&
                    errno != ENOSYS) {
                        error("unable to limit pcap descriptor");
                }
#endif
                dlt = pcap_datalink(pd);
                dlt_name = pcap_datalink_val_to_name(dlt);
                if (dlt_name == NULL) {
                        fprintf(stderr, "reading from file %s, link-type %u\n",
                            RFileName, dlt);
                } else {
                        fprintf(stderr,
                            "reading from file %s, link-type %s (%s)\n",
                            RFileName, dlt_name,
                            pcap_datalink_val_to_description(dlt));
                }
        } else {
                /*
                 * We're doing a live capture.
                 */
                if (device == NULL) {
                        /*
                         * No interface was specified.  Pick one.
                         */
#ifdef HAVE_PCAP_FINDALLDEVS
                        /*
                         * Find the list of interfaces, and pick
                         * the first interface.
                         */
                        if (pcap_findalldevs(&devlist, ebuf) >= 0 &&
                            devlist != NULL) {
                                device = strdup(devlist->name);
                                pcap_freealldevs(devlist);
                        }
#else /* HAVE_PCAP_FINDALLDEVS */
                        /*
                         * Use whatever interface pcap_lookupdev()
                         * chooses.
                         */
                        device = pcap_lookupdev(ebuf);
#endif
                        if (device == NULL)
                                error("%s", ebuf);
                }

                /*
                 * Try to open the interface with the specified name.
                 */
                pd = open_interface(device, ndo, ebuf);
                if (pd == NULL) {
                        /*
                         * That failed.  If we can get a list of
                         * interfaces, and the interface name
                         * is purely numeric, try to use it as
                         * a 1-based index in the list of
                         * interfaces.
                         */
#ifdef HAVE_PCAP_FINDALLDEVS
                        devnum = parse_interface_number(device);
                        if (devnum == -1) {
                                /*
                                 * It's not a number; just report
                                 * the open error and fail.
                                 */
                                error("%s", ebuf);
                        }

                        /*
                         * OK, it's a number; try to find the
                         * interface with that index, and try
                         * to open it.
                         *
                         * find_interface_by_number() exits if it
                         * couldn't be found.
                         */
                        device = find_interface_by_number(devnum);
                        pd = open_interface(device, ndo, ebuf);
                        if (pd == NULL)
                                error("%s", ebuf);
#else /* HAVE_PCAP_FINDALLDEVS */
                        /*
                         * We can't get a list of interfaces; just
                         * fail.
                         */
                        error("%s", ebuf);
#endif /* HAVE_PCAP_FINDALLDEVS */
                }

                /*
                 * Let user own process after socket has been opened.
                 */
#ifndef _WIN32
                if (setgid(getgid()) != 0 || setuid(getuid()) != 0)
                        fprintf(stderr, "Warning: setgid/setuid failed !\n");
#endif /* _WIN32 */
#if !defined(HAVE_PCAP_CREATE) && defined(_WIN32)
                if(Bflag != 0)
                        if(pcap_setbuff(pd, Bflag)==-1){
                                error("%s", pcap_geterr(pd));
                        }
#endif /* !defined(HAVE_PCAP_CREATE) && defined(_WIN32) */
                if (Lflag)
                        show_dlts_and_exit(pd, device);
                if (yflag_dlt >= 0) {
#ifdef HAVE_PCAP_SET_DATALINK
                        if (pcap_set_datalink(pd, yflag_dlt) < 0)
                                error("%s", pcap_geterr(pd));
#else
                        /*
                         * We don't actually support changing the
                         * data link type, so we only let them
                         * set it to what it already is.
                         */
                        if (yflag_dlt != pcap_datalink(pd)) {
                                error("%s is not one of the DLTs supported by this device\n",
                                      yflag_dlt_name);
                        }
#endif
                        (void)fprintf(stderr, "%s: data link type %s\n",
                                      program_name, yflag_dlt_name);
                        (void)fflush(stderr);
                }
                i = pcap_snapshot(pd);
                if (ndo->ndo_snaplen < i) {
                        warning("snaplen raised from %d to %d", ndo->ndo_snaplen, i);
                        ndo->ndo_snaplen = i;
                }
                if(ndo->ndo_fflag != 0) {
                        if (pcap_lookupnet(device, &localnet, &netmask, ebuf) < 0) {
                                warning("foreign (-f) flag used but: %s", ebuf);
                        }
                }

        }
        if (infile)
                cmdbuf = read_infile(infile);
        else
                cmdbuf = copy_argv(&argv[optind]);

#ifdef HAVE_PCAP_SET_OPTIMIZER_DEBUG
        pcap_set_optimizer_debug(dflag);
#endif
        if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
                error("%s", pcap_geterr(pd));
        if (dflag) {
                bpf_dump(&fcode, dflag);
                pcap_close(pd);
                free(cmdbuf);
                pcap_freecode(&fcode);
                exit_tcpdump(0);
        }
        init_print(ndo, localnet, netmask, timezone_offset);

#ifndef _WIN32
        (void)setsignal(SIGPIPE, cleanup);
        (void)setsignal(SIGTERM, cleanup);
        (void)setsignal(SIGINT, cleanup);
#endif /* _WIN32 */
#if defined(HAVE_FORK) || defined(HAVE_VFORK)
        (void)setsignal(SIGCHLD, child_cleanup);
#endif
        /* Cooperate with nohup(1) */
#ifndef _WIN32
        if ((oldhandler = setsignal(SIGHUP, cleanup)) != SIG_DFL)
                (void)setsignal(SIGHUP, oldhandler);
#endif /* _WIN32 */

#ifndef _WIN32
        /*
         * If a user name was specified with "-Z", attempt to switch to
         * that user's UID.  This would probably be used with sudo,
         * to allow tcpdump to be run in a special restricted
         * account (if you just want to allow users to open capture
         * devices, and can't just give users that permission,
         * you'd make tcpdump set-UID or set-GID).
         *
         * Tcpdump doesn't necessarily write only to one savefile;
         * the general only way to allow a -Z instance to write to
         * savefiles as the user under whose UID it's run, rather
         * than as the user specified with -Z, would thus be to switch
         * to the original user ID before opening a capture file and
         * then switch back to the -Z user ID after opening the savefile.
         * Switching to the -Z user ID only after opening the first
         * savefile doesn't handle the general case.
         */

        if (getuid() == 0 || geteuid() == 0) {
#ifdef HAVE_LIBCAP_NG
                /* Initialize capng */
                capng_clear(CAPNG_SELECT_BOTH);
                if (username) {
                        capng_updatev(
                                CAPNG_ADD,
                                CAPNG_PERMITTED | CAPNG_EFFECTIVE,
                                CAP_SETUID,
                                CAP_SETGID,
                                -1);
                }

                if (WFileName) {
                        capng_update(
                                CAPNG_ADD,
                                CAPNG_PERMITTED | CAPNG_EFFECTIVE,
                                CAP_DAC_OVERRIDE
                                );
                }
                capng_apply(CAPNG_SELECT_BOTH);
#endif /* HAVE_LIBCAP_NG */
                if (username || chroot_dir)
                        droproot(username, chroot_dir);

        }
#endif /* _WIN32 */

        if (pcap_setfilter(pd, &fcode) < 0)
                error("%s", pcap_geterr(pd));
#ifdef HAVE_CAPSICUM
        if (RFileName == NULL && VFileName == NULL) {
                static const unsigned long cmds[] = { BIOCGSTATS, BIOCROTZBUF };

                cap_rights_init(&rights, CAP_IOCTL, CAP_READ);
                if (cap_rights_limit(pcap_fileno(pd), &rights) < 0 &&
                    errno != ENOSYS) {
                        error("unable to limit pcap descriptor");
                }
                if (cap_ioctls_limit(pcap_fileno(pd), cmds,
                    sizeof(cmds) / sizeof(cmds[0])) < 0 && errno != ENOSYS) {
                        error("unable to limit ioctls on pcap descriptor");
                }
        }
#endif
        if (WFileName) {
                pcap_dumper_t *p;
                /* Do not exceed the default PATH_MAX for files. */
                dumpinfo.CurrentFileName = (char *)malloc(PATH_MAX + 1);

                if (dumpinfo.CurrentFileName == NULL)
                        error("malloc of dumpinfo.CurrentFileName");

                /* We do not need numbering for dumpfiles if Cflag isn't set. */
                if (Cflag != 0)
                  MakeFilename(dumpinfo.CurrentFileName, WFileName, 0, WflagChars);
                else
                  MakeFilename(dumpinfo.CurrentFileName, WFileName, 0, 0);

                p = pcap_dump_open(pd, dumpinfo.CurrentFileName);
#ifdef HAVE_LIBCAP_NG
                /* Give up CAP_DAC_OVERRIDE capability.
                 * Only allow it to be restored if the -C or -G flag have been
                 * set since we may need to create more files later on.
                 */
                capng_update(
                        CAPNG_DROP,
                        (Cflag || Gflag ? 0 : CAPNG_PERMITTED)
                                | CAPNG_EFFECTIVE,
                        CAP_DAC_OVERRIDE
                        );
                capng_apply(CAPNG_SELECT_BOTH);
#endif /* HAVE_LIBCAP_NG */
                if (p == NULL)
                        error("%s", pcap_geterr(pd));
#ifdef HAVE_CAPSICUM
                set_dumper_capsicum_rights(p);
#endif
                if (Cflag != 0 || Gflag != 0) {
#ifdef HAVE_CAPSICUM
                        dumpinfo.WFileName = strdup(basename(WFileName));
                        if (dumpinfo.WFileName == NULL) {
                                error("Unable to allocate memory for file %s",
                                    WFileName);
                        }
                        dumpinfo.dirfd = open(dirname(WFileName),
                            O_DIRECTORY | O_RDONLY);
                        if (dumpinfo.dirfd < 0) {
                                error("unable to open directory %s",
                                    dirname(WFileName));
                        }
                        cap_rights_init(&rights, CAP_CREATE, CAP_FCNTL,
                            CAP_FTRUNCATE, CAP_LOOKUP, CAP_SEEK, CAP_WRITE);
                        if (cap_rights_limit(dumpinfo.dirfd, &rights) < 0 &&
                            errno != ENOSYS) {
                                error("unable to limit directory rights");
                        }
                        if (cap_fcntls_limit(dumpinfo.dirfd, CAP_FCNTL_GETFL) < 0 &&
                            errno != ENOSYS) {
                                error("unable to limit dump descriptor fcntls");
                        }
#else   /* !HAVE_CAPSICUM */
                        dumpinfo.WFileName = WFileName;
#endif
                        callback = dump_packet_and_trunc;
                        dumpinfo.pd = pd;
                        dumpinfo.p = p;
                        pcap_userdata = (u_char *)&dumpinfo;
                } else {
                        callback = dump_packet;
                        pcap_userdata = (u_char *)p;
                }
#ifdef HAVE_PCAP_DUMP_FLUSH
                if (Uflag)
                        pcap_dump_flush(p);
#endif
        } else {
                dlt = pcap_datalink(pd);
                ndo->ndo_if_printer = get_if_printer(ndo, dlt);
                callback = print_packet;
                pcap_userdata = (u_char *)ndo;
        }

#ifdef SIGNAL_REQ_INFO
        /*
         * We can't get statistics when reading from a file rather
         * than capturing from a device.
         */
        if (RFileName == NULL)
                (void)setsignal(SIGNAL_REQ_INFO, requestinfo);
#endif

        if (ndo->ndo_vflag > 0 && WFileName) {
                /*
                 * When capturing to a file, "-v" means tcpdump should,
                 * every 10 seconds, "v"erbosely report the number of
                 * packets captured.
                 */
#ifdef USE_WIN32_MM_TIMER
                /* call verbose_stats_dump() each 1000 +/-100msec */
                timer_id = timeSetEvent(1000, 100, verbose_stats_dump, 0, TIME_PERIODIC);
                setvbuf(stderr, NULL, _IONBF, 0);
#elif defined(HAVE_ALARM)
                (void)setsignal(SIGALRM, verbose_stats_dump);
                alarm(1);
#endif
        }

        if (RFileName == NULL) {
                /*
                 * Live capture (if -V was specified, we set RFileName
                 * to a file from the -V file).  Print a message to
                 * the standard error on UN*X.
                 */
                if (!ndo->ndo_vflag && !WFileName) {
                        (void)fprintf(stderr,
                            "%s: verbose output suppressed, use -v or -vv for full protocol decode\n",
                            program_name);
                } else
                        (void)fprintf(stderr, "%s: ", program_name);
                dlt = pcap_datalink(pd);
                dlt_name = pcap_datalink_val_to_name(dlt);
                if (dlt_name == NULL) {
                        (void)fprintf(stderr, "listening on %s, link-type %u, capture size %u bytes\n",
                            device, dlt, ndo->ndo_snaplen);
                } else {
                        (void)fprintf(stderr, "listening on %s, link-type %s (%s), capture size %u bytes\n",
                            device, dlt_name,
                            pcap_datalink_val_to_description(dlt), ndo->ndo_snaplen);
                }
                (void)fflush(stderr);
        }

#ifdef HAVE_CAPSICUM
        cansandbox = (ndo->ndo_nflag && VFileName == NULL && zflag == NULL);
        if (cansandbox && cap_enter() < 0 && errno != ENOSYS)
                error("unable to enter the capability mode");
#endif  /* HAVE_CAPSICUM */

        do {
                status = pcap_loop(pd, cnt, callback, pcap_userdata);
                if (WFileName == NULL) {
                        /*
                         * We're printing packets.  Flush the printed output,
                         * so it doesn't get intermingled with error output.
                         */
                        if (status == -2) {
                                /*
                                 * We got interrupted, so perhaps we didn't
                                 * manage to finish a line we were printing.
                                 * Print an extra newline, just in case.
                                 */
                                putchar('\n');
                        }
                        (void)fflush(stdout);
                }
                if (status == -2) {
                        /*
                         * We got interrupted. If we are reading multiple
                         * files (via -V) set these so that we stop.
                         */
                        VFileName = NULL;
                        ret = NULL;
                }
                if (status == -1) {
                        /*
                         * Error.  Report it.
                         */
                        (void)fprintf(stderr, "%s: pcap_loop: %s\n",
                            program_name, pcap_geterr(pd));
                }
                if (RFileName == NULL) {
                        /*
                         * We're doing a live capture.  Report the capture
                         * statistics.
                         */
                        info(1);
                }
                pcap_close(pd);
                if (VFileName != NULL) {
                        ret = get_next_file(VFile, VFileLine);
                        if (ret) {
                                int new_dlt;

                                RFileName = VFileLine;
                                pd = pcap_open_offline(RFileName, ebuf);
                                if (pd == NULL)
                                        error("%s", ebuf);
#ifdef HAVE_CAPSICUM
                                cap_rights_init(&rights, CAP_READ);
                                if (cap_rights_limit(fileno(pcap_file(pd)),
                                    &rights) < 0 && errno != ENOSYS) {
                                        error("unable to limit pcap descriptor");
                                }
#endif
                                new_dlt = pcap_datalink(pd);
                                if (new_dlt != dlt) {
                                        /*
                                         * The new file has a different
                                         * link-layer header type from the
                                         * previous one.
                                         */
                                        if (WFileName != NULL) {
                                                /*
                                                 * We're writing raw packets
                                                 * that match the filter to
                                                 * a pcap file.  pcap files
                                                 * don't support multiple
                                                 * different link-layer
                                                 * header types, so we fail
                                                 * here.
                                                 */
                                                error("%s: new dlt does not match original", RFileName);
                                        }

                                        /*
                                         * We're printing the decoded packets;
                                         * switch to the new DLT.
                                         *
                                         * To do that, we need to change
                                         * the printer, change the DLT name,
                                         * and recompile the filter with
                                         * the new DLT.
                                         */
                                        dlt = new_dlt;
                                        ndo->ndo_if_printer = get_if_printer(ndo, dlt);
                                        if (pcap_compile(pd, &fcode, cmdbuf, Oflag, netmask) < 0)
                                                error("%s", pcap_geterr(pd));
                                }

                                /*
                                 * Set the filter on the new file.
                                 */
                                if (pcap_setfilter(pd, &fcode) < 0)
                                        error("%s", pcap_geterr(pd));

                                /*
                                 * Report the new file.
                                 */
                                dlt_name = pcap_datalink_val_to_name(dlt);
                                if (dlt_name == NULL) {
                                        fprintf(stderr, "reading from file %s, link-type %u\n",
                                            RFileName, dlt);
                                } else {
                                        fprintf(stderr,
                                        "reading from file %s, link-type %s (%s)\n",
                                            RFileName, dlt_name,
                                            pcap_datalink_val_to_description(dlt));
                                }
                        }
                }
        }
        while (ret != NULL);

        free(cmdbuf);
        pcap_freecode(&fcode);
        exit_tcpdump(status == -1 ? 1 : 0);
}

/* make a clean exit on interrupts */
static RETSIGTYPE
cleanup(int signo _U_)
{
#ifdef USE_WIN32_MM_TIMER
        if (timer_id)
                timeKillEvent(timer_id);
        timer_id = 0;
#elif defined(HAVE_ALARM)
        alarm(0);
#endif

#ifdef HAVE_PCAP_BREAKLOOP
        /*
         * We have "pcap_breakloop()"; use it, so that we do as little
         * as possible in the signal handler (it's probably not safe
         * to do anything with standard I/O streams in a signal handler -
         * the ANSI C standard doesn't say it is).
         */
        pcap_breakloop(pd);
#else
        /*
         * We don't have "pcap_breakloop()"; this isn't safe, but
         * it's the best we can do.  Print the summary if we're
         * not reading from a savefile - i.e., if we're doing a
         * live capture - and exit.
         */
        if (pd != NULL && pcap_file(pd) == NULL) {
                /*
                 * We got interrupted, so perhaps we didn't
                 * manage to finish a line we were printing.
                 * Print an extra newline, just in case.
                 */
                putchar('\n');
                (void)fflush(stdout);
                info(1);
        }
        exit_tcpdump(0);
#endif
}

/*
  On windows, we do not use a fork, so we do not care less about
  waiting a child processes to die
 */
#if defined(HAVE_FORK) || defined(HAVE_VFORK)
static RETSIGTYPE
child_cleanup(int signo _U_)
{
  wait(NULL);
}
#endif /* HAVE_FORK && HAVE_VFORK */

static void
info(register int verbose)
{
        struct pcap_stat stats;

        /*
         * Older versions of libpcap didn't set ps_ifdrop on some
         * platforms; initialize it to 0 to handle that.
         */
        stats.ps_ifdrop = 0;
        if (pcap_stats(pd, &stats) < 0) {
                (void)fprintf(stderr, "pcap_stats: %s\n", pcap_geterr(pd));
                infoprint = 0;
                return;
        }

        if (!verbose)
                fprintf(stderr, "%s: ", program_name);

        (void)fprintf(stderr, "%u packet%s captured", packets_captured,
            PLURAL_SUFFIX(packets_captured));
        if (!verbose)
                fputs(", ", stderr);
        else
                putc('\n', stderr);
        (void)fprintf(stderr, "%u packet%s received by filter", stats.ps_recv,
            PLURAL_SUFFIX(stats.ps_recv));
        if (!verbose)
                fputs(", ", stderr);
        else
                putc('\n', stderr);
        (void)fprintf(stderr, "%u packet%s dropped by kernel", stats.ps_drop,
            PLURAL_SUFFIX(stats.ps_drop));
        if (stats.ps_ifdrop != 0) {
                if (!verbose)
                        fputs(", ", stderr);
                else
                        putc('\n', stderr);
                (void)fprintf(stderr, "%u packet%s dropped by interface\n",
                    stats.ps_ifdrop, PLURAL_SUFFIX(stats.ps_ifdrop));
        } else
                putc('\n', stderr);
        infoprint = 0;
}

#if defined(HAVE_FORK) || defined(HAVE_VFORK)
#ifdef HAVE_FORK
#define fork_subprocess() fork()
#else
#define fork_subprocess() vfork()
#endif
static void
compress_savefile(const char *filename)
{
        pid_t child;

        child = fork_subprocess();
        if (child == -1) {
                fprintf(stderr,
                        "compress_savefile: fork failed: %s\n",
                        pcap_strerror(errno));
                return;
        }
        if (child != 0) {
                /* Parent process. */
                return;
        }

        /*
         * Child process.
         * Set to lowest priority so that this doesn't disturb the capture.
         */
#ifdef NZERO
        setpriority(PRIO_PROCESS, 0, NZERO - 1);
#else
        setpriority(PRIO_PROCESS, 0, 19);
#endif
        if (execlp(zflag, zflag, filename, (char *)NULL) == -1)
                fprintf(stderr,
                        "compress_savefile: execlp(%s, %s) failed: %s\n",
                        zflag,
                        filename,
                        pcap_strerror(errno));
#ifdef HAVE_FORK
        exit(1);
#else
        _exit(1);
#endif
}
#else  /* HAVE_FORK && HAVE_VFORK */
static void
compress_savefile(const char *filename)
{
        fprintf(stderr,
                "compress_savefile failed. Functionality not implemented under your system\n");
}
#endif /* HAVE_FORK && HAVE_VFORK */

static void
dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
        struct dump_info *dump_info;

        ++packets_captured;

        ++infodelay;

        dump_info = (struct dump_info *)user;

        /*
         * XXX - this won't force the file to rotate on the specified time
         * boundary, but it will rotate on the first packet received after the
         * specified Gflag number of seconds. Note: if a Gflag time boundary
         * and a Cflag size boundary coincide, the time rotation will occur
         * first thereby cancelling the Cflag boundary (since the file should
         * be 0).
         */
        if (Gflag != 0) {
                /* Check if it is time to rotate */
                time_t t;

                /* Get the current time */
                if ((t = time(NULL)) == (time_t)-1) {
                        error("dump_and_trunc_packet: can't get current_time: %s",
                            pcap_strerror(errno));
                }


                /* If the time is greater than the specified window, rotate */
                if (t - Gflag_time >= Gflag) {
#ifdef HAVE_CAPSICUM
                        FILE *fp;
                        int fd;
#endif

                        /* Update the Gflag_time */
                        Gflag_time = t;
                        /* Update Gflag_count */
                        Gflag_count++;
                        /*
                         * Close the current file and open a new one.
                         */
                        pcap_dump_close(dump_info->p);

                        /*
                         * Compress the file we just closed, if the user asked for it
                         */
                        if (zflag != NULL)
                                compress_savefile(dump_info->CurrentFileName);

                        /*
                         * Check to see if we've exceeded the Wflag (when
                         * not using Cflag).
                         */
                        if (Cflag == 0 && Wflag > 0 && Gflag_count >= Wflag) {
                                (void)fprintf(stderr, "Maximum file limit reached: %d\n",
                                    Wflag);
                                exit_tcpdump(0);
                                /* NOTREACHED */
                        }
                        if (dump_info->CurrentFileName != NULL)
                                free(dump_info->CurrentFileName);
                        /* Allocate space for max filename + \0. */
                        dump_info->CurrentFileName = (char *)malloc(PATH_MAX + 1);
                        if (dump_info->CurrentFileName == NULL)
                                error("dump_packet_and_trunc: malloc");
                        /*
                         * Gflag was set otherwise we wouldn't be here. Reset the count
                         * so multiple files would end with 1,2,3 in the filename.
                         * The counting is handled with the -C flow after this.
                         */
                        Cflag_count = 0;

                        /*
                         * This is always the first file in the Cflag
                         * rotation: e.g. 0
                         * We also don't need numbering if Cflag is not set.
                         */
                        if (Cflag != 0)
                                MakeFilename(dump_info->CurrentFileName, dump_info->WFileName, 0,
                                    WflagChars);
                        else
                                MakeFilename(dump_info->CurrentFileName, dump_info->WFileName, 0, 0);

#ifdef HAVE_LIBCAP_NG
                        capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
                        capng_apply(CAPNG_SELECT_BOTH);
#endif /* HAVE_LIBCAP_NG */
#ifdef HAVE_CAPSICUM
                        fd = openat(dump_info->dirfd,
                            dump_info->CurrentFileName,
                            O_CREAT | O_WRONLY | O_TRUNC, 0644);
                        if (fd < 0) {
                                error("unable to open file %s",
                                    dump_info->CurrentFileName);
                        }
                        fp = fdopen(fd, "w");
                        if (fp == NULL) {
                                error("unable to fdopen file %s",
                                    dump_info->CurrentFileName);
                        }
                        dump_info->p = pcap_dump_fopen(dump_info->pd, fp);
#else   /* !HAVE_CAPSICUM */
                        dump_info->p = pcap_dump_open(dump_info->pd, dump_info->CurrentFileName);
#endif
#ifdef HAVE_LIBCAP_NG
                        capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
                        capng_apply(CAPNG_SELECT_BOTH);
#endif /* HAVE_LIBCAP_NG */
                        if (dump_info->p == NULL)
                                error("%s", pcap_geterr(pd));
#ifdef HAVE_CAPSICUM
                        set_dumper_capsicum_rights(dump_info->p);
#endif
                }
        }

        /*
         * XXX - this won't prevent capture files from getting
         * larger than Cflag - the last packet written to the
         * file could put it over Cflag.
         */
        if (Cflag != 0) {
                long size = pcap_dump_ftell(dump_info->p);

                if (size == -1)
                        error("ftell fails on output file");
                if (size > Cflag) {
#ifdef HAVE_CAPSICUM
                        FILE *fp;
                        int fd;
#endif

                        /*
                         * Close the current file and open a new one.
                         */
                        pcap_dump_close(dump_info->p);

                        /*
                         * Compress the file we just closed, if the user
                         * asked for it.
                         */
                        if (zflag != NULL)
                                compress_savefile(dump_info->CurrentFileName);

                        Cflag_count++;
                        if (Wflag > 0) {
                                if (Cflag_count >= Wflag)
                                        Cflag_count = 0;
                        }
                        if (dump_info->CurrentFileName != NULL)
                                free(dump_info->CurrentFileName);
                        dump_info->CurrentFileName = (char *)malloc(PATH_MAX + 1);
                        if (dump_info->CurrentFileName == NULL)
                                error("dump_packet_and_trunc: malloc");
                        MakeFilename(dump_info->CurrentFileName, dump_info->WFileName, Cflag_count, WflagChars);
#ifdef HAVE_LIBCAP_NG
                        capng_update(CAPNG_ADD, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
                        capng_apply(CAPNG_SELECT_BOTH);
#endif /* HAVE_LIBCAP_NG */
#ifdef HAVE_CAPSICUM
                        fd = openat(dump_info->dirfd, dump_info->CurrentFileName,
                            O_CREAT | O_WRONLY | O_TRUNC, 0644);
                        if (fd < 0) {
                                error("unable to open file %s",
                                    dump_info->CurrentFileName);
                        }
                        fp = fdopen(fd, "w");
                        if (fp == NULL) {
                                error("unable to fdopen file %s",
                                    dump_info->CurrentFileName);
                        }
                        dump_info->p = pcap_dump_fopen(dump_info->pd, fp);
#else   /* !HAVE_CAPSICUM */
                        dump_info->p = pcap_dump_open(dump_info->pd, dump_info->CurrentFileName);
#endif
#ifdef HAVE_LIBCAP_NG
                        capng_update(CAPNG_DROP, CAPNG_EFFECTIVE, CAP_DAC_OVERRIDE);
                        capng_apply(CAPNG_SELECT_BOTH);
#endif /* HAVE_LIBCAP_NG */
                        if (dump_info->p == NULL)
                                error("%s", pcap_geterr(pd));
#ifdef HAVE_CAPSICUM
                        set_dumper_capsicum_rights(dump_info->p);
#endif
                }
        }

        pcap_dump((u_char *)dump_info->p, h, sp);
#ifdef HAVE_PCAP_DUMP_FLUSH
        if (Uflag)
                pcap_dump_flush(dump_info->p);
#endif

        --infodelay;
        if (infoprint)
                info(0);
}

static void
dump_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
        ++packets_captured;

        ++infodelay;

        pcap_dump(user, h, sp);
#ifdef HAVE_PCAP_DUMP_FLUSH
        if (Uflag)
                pcap_dump_flush((pcap_dumper_t *)user);
#endif

        --infodelay;
        if (infoprint)
                info(0);
}

static void
print_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
        ++packets_captured;

        ++infodelay;

        pretty_print_packet((netdissect_options *)user, h, sp, packets_captured);

        --infodelay;
        if (infoprint)
                info(0);
}

#ifdef _WIN32
        /*
         * XXX - there should really be libpcap calls to get the version
         * number as a string (the string would be generated from #defines
         * at run time, so that it's not generated from string constants
         * in the library, as, on many UNIX systems, those constants would
         * be statically linked into the application executable image, and
         * would thus reflect the version of libpcap on the system on
         * which the application was *linked*, not the system on which it's
         * *running*.
         *
         * That routine should be documented, unlike the "version[]"
         * string, so that UNIX vendors providing their own libpcaps
         * don't omit it (as a couple of vendors have...).
         *
         * Packet.dll should perhaps also export a routine to return the
         * version number of the Packet.dll code, to supply the
         * "Wpcap_version" information on Windows.
         */
        char WDversion[]="current-git.tcpdump.org";
#if !defined(HAVE_GENERATED_VERSION)
        char version[]="current-git.tcpdump.org";
#endif
        char pcap_version[]="current-git.tcpdump.org";
        char Wpcap_version[]="3.1";
#endif

#ifdef SIGNAL_REQ_INFO
RETSIGTYPE requestinfo(int signo _U_)
{
        if (infodelay)
                ++infoprint;
        else
                info(0);
}
#endif

/*
 * Called once each second in verbose mode while dumping to file
 */
#ifdef USE_WIN32_MM_TIMER
void CALLBACK verbose_stats_dump (UINT timer_id _U_, UINT msg _U_, DWORD_PTR arg _U_,
                                  DWORD_PTR dw1 _U_, DWORD_PTR dw2 _U_)
{
        if (infodelay == 0)
                fprintf(stderr, "Got %u\r", packets_captured);
}
#elif defined(HAVE_ALARM)
static void verbose_stats_dump(int sig _U_)
{
        if (infodelay == 0)
                fprintf(stderr, "Got %u\r", packets_captured);
        alarm(1);
}
#endif

USES_APPLE_DEPRECATED_API
static void
print_version(void)
{
        extern char version[];
#ifndef HAVE_PCAP_LIB_VERSION
#if defined(_WIN32) || defined(HAVE_PCAP_VERSION)
        extern char pcap_version[];
#else /* defined(_WIN32) || defined(HAVE_PCAP_VERSION) */
        static char pcap_version[] = "unknown";
#endif /* defined(_WIN32) || defined(HAVE_PCAP_VERSION) */
#endif /* HAVE_PCAP_LIB_VERSION */
        const char *smi_version_string;

#ifdef HAVE_PCAP_LIB_VERSION
#ifdef _WIN32
        (void)fprintf(stderr, "%s version %s, based on tcpdump version %s\n", program_name, WDversion, version);
#else /* _WIN32 */
        (void)fprintf(stderr, "%s version %s\n", program_name, version);
#endif /* _WIN32 */
        (void)fprintf(stderr, "%s\n",pcap_lib_version());
#else /* HAVE_PCAP_LIB_VERSION */
#ifdef _WIN32
        (void)fprintf(stderr, "%s version %s, based on tcpdump version %s\n", program_name, WDversion, version);
        (void)fprintf(stderr, "WinPcap version %s, based on libpcap version %s\n",Wpcap_version, pcap_version);
#else /* _WIN32 */
        (void)fprintf(stderr, "%s version %s\n", program_name, version);
        (void)fprintf(stderr, "libpcap version %s\n", pcap_version);
#endif /* _WIN32 */
#endif /* HAVE_PCAP_LIB_VERSION */

#if defined(HAVE_LIBCRYPTO) && defined(SSLEAY_VERSION)
        (void)fprintf (stderr, "%s\n", SSLeay_version(SSLEAY_VERSION));
#endif

        smi_version_string = nd_smi_version_string();
        if (smi_version_string != NULL)
                (void)fprintf (stderr, "SMI-library: %s\n", smi_version_string);
}
USES_APPLE_RST

static void
print_usage(void)
{
        print_version();
        (void)fprintf(stderr,
"Usage: %s [-aAbd" D_FLAG "efhH" I_FLAG J_FLAG "KlLnNOpqStu" U_FLAG "vxX#]" B_FLAG_USAGE " [ -c count ]\n", program_name);
        (void)fprintf(stderr,
"\t\t[ -C file_size ] [ -E algo:secret ] [ -F file ] [ -G seconds ]\n");
        (void)fprintf(stderr,
"\t\t[ -i interface ]" j_FLAG_USAGE " [ -M secret ] [ --number ]\n");
#ifdef HAVE_PCAP_SETDIRECTION
        (void)fprintf(stderr,
"\t\t[ -Q in|out|inout ]\n");
#endif
        (void)fprintf(stderr,
"\t\t[ -r file ] [ -s snaplen ] ");
#ifdef HAVE_PCAP_SET_TSTAMP_PRECISION
        (void)fprintf(stderr, "[ --time-stamp-precision precision ]\n");
        (void)fprintf(stderr,
"\t\t");
#endif
#ifdef HAVE_PCAP_SET_IMMEDIATE_MODE
        (void)fprintf(stderr, "[ --immediate-mode ] ");
#endif
        (void)fprintf(stderr, "[ -T type ] [ --version ] [ -V file ]\n");
        (void)fprintf(stderr,
"\t\t[ -w file ] [ -W filecount ] [ -y datalinktype ] [ -z postrotate-command ]\n");
        (void)fprintf(stderr,
"\t\t[ -Z user ] [ expression ]\n");
}
/*
 * Local Variables:
 * c-style: whitesmith
 * c-basic-offset: 8
 * End:
 */