cse 2410 f13 wireshark

/**-*-C-*-**********************************************************************

 *

 * text2pcap.c

 *

 * Utility to convert an ASCII hexdump into a libpcap-format capture file

 *

 * (c) Copyright 2001 Ashok Narayanan <ashokn@cisco.com>

 *

 * $Id$

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 *******************************************************************************/

/*******************************************************************************

 *

 * This utility reads in an ASCII hexdump of this common format:

 *

 * 00000000  00 E0 1E A7 05 6F 00 10 5A A0 B9 12 08 00 46 00 .....o..Z.....F.

 * 00000010  03 68 00 00 00 00 0A 2E EE 33 0F 19 08 7F 0F 19 .h.......3.....

 * 00000020  03 80 94 04 00 00 10 01 16 A2 0A 00 03 50 00 0C .............P..

 * 00000030  01 01 0F 19 03 80 11 01 1E 61 00 0C 03 01 0F 19 .........a......

 *

 * Each bytestring line consists of an offset, one or more bytes, and

 * text at the end. An offset is defined as a hex string of more than

 * two characters. A byte is defined as a hex string of exactly two

 * characters. The text at the end is ignored, as is any text before

 * the offset. Bytes read from a bytestring line are added to the

 * current packet only if all the following conditions are satisfied:

 *

 * - No text appears between the offset and the bytes (any bytes appearing after

 *   such text would be ignored)

 *

 * - The offset must be arithmetically correct, i.e. if the offset is 00000020, then

 *   exactly 32 bytes must have been read into this packet before this. If the offset

 *   is wrong, the packet is immediately terminated

 *

 * A packet start is signaled by a zero offset.

 *

 * Lines starting with #TEXT2PCAP are directives. These allow the user

 * to embed instructions into the capture file which allows text2pcap

 * to take some actions (e.g. specifying the encapsulation

 * etc.). Currently no directives are implemented.

 *

 * Lines beginning with # which are not directives are ignored as

 * comments. Currently all non-hexdump text is ignored by text2pcap;

 * in the future, text processing may be added, but lines prefixed

 * with '#' will still be ignored.

 *

 * The output is a libpcap packet containing Ethernet frames by

 * default. This program takes options which allow the user to add

 * dummy Ethernet, IP and UDP or TCP headers to the packets in order

 * to allow dumps of L3 or higher protocols to be decoded.

 *

 * Considerable flexibility is built into this code to read hexdumps

 * of slightly different formats. For example, any text prefixing the

 * hexdump line is dropped (including mail forwarding '>'). The offset

 * can be any hex number of four digits or greater.

 *

 * This converter cannot read a single packet greater than 64KiB-1. Packet

 * snaplength is automatically set to 64KiB-1.

 */

#include "config.h"

/*

 * Just make sure we include the prototype for strptime as well

 * (needed for glibc 2.2) but make sure we do this only if not

 * yet defined.

 */

#ifndef __USE_XOPEN

#  define __USE_XOPEN

#endif

#ifndef _XOPEN_SOURCE

#  ifndef __sun

#    define _XOPEN_SOURCE 600

#  endif

#endif

/*

 * Defining _XOPEN_SOURCE is needed on some platforms, e.g. platforms

 * using glibc, to expand the set of things system header files define.

 *

 * Unfortunately, on other platforms, such as some versions of Solaris

 * (including Solaris 10), it *reduces* that set as well, causing

 * strptime() not to be declared, presumably because the version of the

 * X/Open spec that _XOPEN_SOURCE implies doesn't include strptime() and

 * blah blah blah namespace pollution blah blah blah.

 *

 * So we define __EXTENSIONS__ so that "strptime()" is declared.

 */

#ifndef __EXTENSIONS__

#  define __EXTENSIONS__

#endif

#include <ctype.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <wsutil/file_util.h>

#include <time.h>

#include <glib.h>

#ifdef HAVE_UNISTD_H

# include <unistd.h>

#endif

#include <errno.h>

#include <assert.h>

#ifndef HAVE_GETOPT

#include "wsutil/wsgetopt.h"

#endif

#ifdef NEED_STRPTIME_H

# include "wsutil/strptime.h"

#endif

#include "pcapio.h"

#include "text2pcap.h"

#include "svnversion.h"

#ifdef _WIN32

#include <wsutil/unicode-utils.h>

#endif /* _WIN32 */

#ifdef HAVE_ARPA_INET_H

#include <arpa/inet.h>

#endif

#ifdef HAVE_WINSOCK2_H

#include <winsock2.h>       /* needed to define AF_ values on Windows */

#endif

#ifdef NEED_INET_ATON_H

# include "wsutil/inet_aton.h"

#endif

#ifdef HAVE_SYS_SOCKET_H

#include <sys/socket.h>

#endif

#ifdef NEED_INET_V6DEFS_H

# include "wsutil/inet_v6defs.h"

#endif

/*--- Options --------------------------------------------------------------------*/

/* File format */

static gboolean use_pcapng = FALSE;

/* Debug level */

static int debug = 0;

/* Be quiet */

static int quiet = FALSE;

/* Dummy Ethernet header */

static int hdr_ethernet = FALSE;

static guint32 hdr_ethernet_proto = 0;

/* Dummy IP header */

static int hdr_ip = FALSE;

static int hdr_ipv6 = FALSE;

static long hdr_ip_proto = 0;

/* Destination and source addresses for IP header */

static guint32 hdr_ip_dest_addr = 0;

static guint32 hdr_ip_src_addr = 0;

static guint8 hdr_ipv6_dest_addr[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

static guint8 hdr_ipv6_src_addr[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

static guint8 NO_IPv6_ADDRESS[16] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};

/* Dummy UDP header */

static int hdr_udp = FALSE;

static guint32 hdr_dest_port = 0;

static guint32 hdr_src_port = 0;

/* Dummy TCP header */

static int hdr_tcp = FALSE;

/* Dummy SCTP header */

static int hdr_sctp = FALSE;

static guint32 hdr_sctp_src  = 0;

static guint32 hdr_sctp_dest = 0;

static guint32 hdr_sctp_tag  = 0;

/* Dummy DATA chunk header */

static int hdr_data_chunk = FALSE;

static guint8  hdr_data_chunk_type = 0;

static guint8  hdr_data_chunk_bits = 0;

static guint32 hdr_data_chunk_tsn  = 0;

static guint16 hdr_data_chunk_sid  = 0;

static guint16 hdr_data_chunk_ssn  = 0;

static guint32 hdr_data_chunk_ppid = 0;

/* ASCII text dump identification */

static int identify_ascii = FALSE;

static gboolean has_direction = FALSE;

static guint32 direction = 0;

/*--- Local date -----------------------------------------------------------------*/

/* This is where we store the packet currently being built */

#define MAX_PACKET 65535

static guint8 packet_buf[MAX_PACKET];

static guint32 header_length;

static guint32 ip_offset;

static guint32 curr_offset;

static guint32 max_offset = MAX_PACKET;

static guint32 packet_start = 0;

static void start_new_packet(gboolean);

/* This buffer contains strings present before the packet offset 0 */

#define PACKET_PREAMBLE_MAX_LEN     2048

static guint8 packet_preamble[PACKET_PREAMBLE_MAX_LEN+1];

static int packet_preamble_len = 0;

/* Number of packets read and written */

static guint32 num_packets_read = 0;

static guint32 num_packets_written = 0;

static guint64 bytes_written = 0;

/* Time code of packet, derived from packet_preamble */

static time_t ts_sec  = 0;

static guint32 ts_usec = 0;

static char *ts_fmt = NULL;

static struct tm timecode_default;

static guint8* pkt_lnstart;

/* Input file */

static const char *input_filename;

static FILE *input_file = NULL;

/* Output file */

static const char *output_filename;

static FILE *output_file = NULL;

/* Offset base to parse */

static guint32 offset_base = 16;

extern FILE *yyin;

/* ----- State machine -----------------------------------------------------------*/

/* Current state of parser */

typedef enum {

    INIT,             /* Waiting for start of new packet */

    START_OF_LINE,    /* Starting from beginning of line */

    READ_OFFSET,      /* Just read the offset */

    READ_BYTE,        /* Just read a byte */

    READ_TEXT         /* Just read text - ignore until EOL */

} parser_state_t;

static parser_state_t state = INIT;

static const char *state_str[] = {"Init",

                           "Start-of-line",

                           "Offset",

                           "Byte",

                           "Text"

};

static const char *token_str[] = {"",

                           "Byte",

                           "Offset",

                           "Directive",

                           "Text",

                           "End-of-line"

};

/* ----- Skeleton Packet Headers --------------------------------------------------*/

typedef struct {

    guint8  dest_addr[6];

    guint8  src_addr[6];

    guint16 l3pid;

} hdr_ethernet_t;

static hdr_ethernet_t HDR_ETHERNET = {

    {0x0a, 0x02, 0x02, 0x02, 0x02, 0x02},

    {0x0a, 0x01, 0x01, 0x01, 0x01, 0x01},

    0};

typedef struct {

    guint8  ver_hdrlen;

    guint8  dscp;

    guint16 packet_length;

    guint16 identification;

    guint8  flags;

    guint8  fragment;

    guint8  ttl;

    guint8  protocol;

    guint16 hdr_checksum;

    guint32 src_addr;

    guint32 dest_addr;

} hdr_ip_t;

static hdr_ip_t HDR_IP = {0x45, 0, 0, 0x3412, 0, 0, 0xff, 0, 0,

#ifdef WORDS_BIGENDIAN

0x0a010101, 0x0a020202

#else

0x0101010a, 0x0202020a

#endif

};

static struct {         /* pseudo header for checksum calculation */

    guint32 src_addr;

    guint32 dest_addr;

    guint8  zero;

    guint8  protocol;

    guint16 length;

} pseudoh;

/* headers taken from glibc */

/* IPv6 address */

struct hdr_in6_addr

{

    union

    {

       guint8  __u6_addr8[16];

       guint16 __u6_addr16[8];

       guint32 __u6_addr32[4];

    } __in6_u;

};

typedef struct {

        union  {

                struct ip6_hdrctl {

                        guint32 ip6_un1_flow;   /* 24 bits of flow-ID */

                        guint16 ip6_un1_plen;   /* payload length */

                        guint8  ip6_un1_nxt;    /* next header */

                        guint8  ip6_un1_hlim;   /* hop limit */

                } ip6_un1;

                guint8 ip6_un2_vfc;       /* 4 bits version, 4 bits priority */

        } ip6_ctlun;

        struct hdr_in6_addr ip6_src;      /* source address */

        struct hdr_in6_addr ip6_dst;      /* destination address */

} hdr_ipv6_t;

static hdr_ipv6_t HDR_IPv6;

static struct {                 /* pseudo header ipv6 for checksum calculation */

        struct  hdr_in6_addr src_addr6;

        struct  hdr_in6_addr dst_addr6;

        guint32 protocol;

        guint32 zero;

} pseudoh6;

typedef struct {

    guint16 source_port;

    guint16 dest_port;

    guint16 length;

    guint16 checksum;

} hdr_udp_t;

static hdr_udp_t HDR_UDP = {0, 0, 0, 0};

typedef struct {

    guint16 source_port;

    guint16 dest_port;

    guint32 seq_num;

    guint32 ack_num;

    guint8  hdr_length;

    guint8  flags;

    guint16 window;

    guint16 checksum;

    guint16 urg;

} hdr_tcp_t;

static hdr_tcp_t HDR_TCP = {0, 0, 0, 0, 0x50, 0, 0, 0, 0};

typedef struct {

    guint16 src_port;

    guint16 dest_port;

    guint32 tag;

    guint32 checksum;

} hdr_sctp_t;

static hdr_sctp_t HDR_SCTP = {0, 0, 0, 0};

typedef struct {

    guint8  type;

    guint8  bits;

    guint16 length;

    guint32 tsn;

    guint16 sid;

    guint16 ssn;

    guint32 ppid;

} hdr_data_chunk_t;

static hdr_data_chunk_t HDR_DATA_CHUNK = {0, 0, 0, 0, 0, 0, 0};

static char tempbuf[64];

/*----------------------------------------------------------------------

 * Stuff for writing a PCap file

 */

#define PCAP_MAGIC          0xa1b2c3d4

#define PCAP_SNAPLEN        0xffff

/* "libpcap" file header (minus magic number). */

struct pcap_hdr {

    guint32 magic;          /* magic */

    guint16 version_major;  /* major version number */

    guint16 version_minor;  /* minor version number */

    guint32 thiszone;       /* GMT to local correction */

    guint32 sigfigs;        /* accuracy of timestamps */

    guint32 snaplen;        /* max length of captured packets, in octets */

    guint32 network;        /* data link type */

};

/* "libpcap" record header. */

struct pcaprec_hdr {

    guint32 ts_sec;         /* timestamp seconds */

    guint32 ts_usec;        /* timestamp microseconds */

    guint32 incl_len;       /* number of octets of packet saved in file */

    guint32 orig_len;       /* actual length of packet */

};

/* Link-layer type; see http://www.tcpdump.org/linktypes.html for details */

static guint32 pcap_link_type = 1;   /* Default is LINKTYPE_ETHERNET */

/*----------------------------------------------------------------------

 * Parse a single hex number

 * Will abort the program if it can't parse the number

 * Pass in TRUE if this is an offset, FALSE if not

 */

static guint32

parse_num (const char *str, int offset)

{

    guint32 num;

    char *c;

    num = (guint32)strtoul(str, &c, offset ? offset_base : 16);

    if (c==str) {

        fprintf(stderr, "FATAL ERROR: Bad hex number? [%s]\n", str);

        exit(-1);

    }

    return num;

}

/*----------------------------------------------------------------------

 * Write this byte into current packet

 */

static void

write_byte (const char *str)

{

    guint32 num;

    num = parse_num(str, FALSE);

    packet_buf[curr_offset] = (guint8) num;

    curr_offset ++;

    if (curr_offset - header_length >= max_offset) /* packet full */

        start_new_packet(TRUE);

}

/*----------------------------------------------------------------------

 * Write a number of bytes into current packet

 */

static void

write_bytes(const char bytes[], guint32 nbytes)

{

    guint32 i;

    if (curr_offset + nbytes < MAX_PACKET) {

        for (i = 0; i < nbytes; i++) {

            packet_buf[curr_offset] = bytes[i];

            curr_offset++;

        }

    }

}

/*----------------------------------------------------------------------

 * Remove bytes from the current packet

 */

static void

unwrite_bytes (guint32 nbytes)

{

    curr_offset -= nbytes;

}

/*----------------------------------------------------------------------

 * Compute one's complement checksum (from RFC1071)

 */

static guint16

in_checksum (void *buf, guint32 count)

{

    guint32 sum = 0;

    guint16 *addr = (guint16 *)buf;

    while (count > 1) {

        /*  This is the inner loop */

        sum += g_ntohs(* (guint16 *) addr);

        addr++;

        count -= 2;

    }

    /*  Add left-over byte, if any */

    if (count > 0)

        sum += g_ntohs(* (guint8 *) addr);

    /*  Fold 32-bit sum to 16 bits */

    while (sum>>16)

        sum = (sum & 0xffff) + (sum >> 16);

    sum = ~sum;

    return g_htons(sum);

}

/* The CRC32C code is taken from draft-ietf-tsvwg-sctpcsum-01.txt.

 * That code is copyrighted by D. Otis and has been modified.

 */

#define CRC32C(c,d) (c=(c>>8)^crc_c[(c^(d))&0xFF])

static guint32 crc_c[256] =

{

0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L,

0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL,

0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL,

0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L,

0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL,

0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L,

0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L,

0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL,

0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL,

0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L,

0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L,

0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL,

0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L,

0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL,

0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL,

0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L,

0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L,

0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L,

0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L,

0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L,

0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L,

0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L,

0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L,

0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L,

0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L,

0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L,

0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L,

0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L,

0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L,

0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L,

0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L,

0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L,

0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL,

0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L,

0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L,

0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL,

0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L,

0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL,

0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL,

0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L,

0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L,

0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL,

0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL,

0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L,

0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL,

0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L,

0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L,

0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL,

0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L,

0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL,

0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL,

0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L,

0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL,

0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L,

0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L,

0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL,

0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL,

0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L,

0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L,

0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL,

0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L,

0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL,

0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL,

0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L,

};

static guint32

crc32c(const guint8* buf, unsigned int len, guint32 crc32_init)

{

    unsigned int i;

    guint32 crc32;

    crc32 = crc32_init;

    for (i = 0; i < len; i++)

        CRC32C(crc32, buf[i]);

    return ( crc32 );

}

static guint32

finalize_crc32c(guint32 crc32)

{

    guint32 result;

    guint8 byte0,byte1,byte2,byte3;

    result = ~crc32;

    byte0 = result & 0xff;

    byte1 = (result>>8) & 0xff;

    byte2 = (result>>16) & 0xff;

    byte3 = (result>>24) & 0xff;

    result = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);

    return ( result );

}

static guint16

number_of_padding_bytes (guint32 length)

{

    guint16 remainder;

    remainder = length % 4;

    if (remainder == 0)

        return 0;

    else

        return 4 - remainder;

}

/*----------------------------------------------------------------------

 * Write current packet out

 */

static void

write_current_packet(gboolean cont)

{

    guint32 length = 0;

    guint16 padding_length = 0;

    int err;

    guint16 ihatemacros;

    gboolean success;

    if (curr_offset > header_length) {

        /* Write the packet */

        /* if defined IPv6 we should rewrite hdr_ethernet_proto anyways */

        if(hdr_ipv6) {

            hdr_ethernet_proto = 0x86DD;

            hdr_ip = FALSE;

        }

        /* Compute packet length */

        length = curr_offset;

        if (hdr_sctp) {

            padding_length = number_of_padding_bytes(length - header_length );

        } else {

            padding_length = 0;

        }

        /* Reset curr_offset, since we now write the headers */

        curr_offset = 0;

        /* Write Ethernet header */

        if (hdr_ethernet) {

            HDR_ETHERNET.l3pid = g_htons(hdr_ethernet_proto);

            write_bytes((const char *)&HDR_ETHERNET, sizeof(HDR_ETHERNET));

        }

        /* Write IP header */

        if (hdr_ip) {

            if(hdr_ip_src_addr) HDR_IP.src_addr = hdr_ip_src_addr;

            if(hdr_ip_dest_addr) HDR_IP.dest_addr = hdr_ip_dest_addr;

            HDR_IP.packet_length = g_htons(length - ip_offset + padding_length);

            HDR_IP.protocol = (guint8) hdr_ip_proto;

            HDR_IP.hdr_checksum = 0;

            HDR_IP.hdr_checksum = in_checksum(&HDR_IP, sizeof(HDR_IP));

            write_bytes((const char *)&HDR_IP, sizeof(HDR_IP));

        } else if (hdr_ipv6) {

            if(memcmp(hdr_ipv6_src_addr, NO_IPv6_ADDRESS, sizeof(struct hdr_in6_addr)))

                memcpy(&HDR_IPv6.ip6_src, &hdr_ipv6_src_addr, sizeof(struct hdr_in6_addr));

            if(memcmp(hdr_ipv6_dest_addr, NO_IPv6_ADDRESS, sizeof(struct hdr_in6_addr)))

                memcpy(&HDR_IPv6.ip6_dst, &hdr_ipv6_dest_addr, sizeof(struct hdr_in6_addr));

            HDR_IPv6.ip6_ctlun.ip6_un2_vfc &= 0x0F;

            HDR_IPv6.ip6_ctlun.ip6_un2_vfc |= (6<< 4);

            HDR_IPv6.ip6_ctlun.ip6_un1.ip6_un1_plen = g_htons(length - ip_offset + padding_length);

            HDR_IPv6.ip6_ctlun.ip6_un1.ip6_un1_nxt  = (guint8) hdr_ip_proto;

            HDR_IPv6.ip6_ctlun.ip6_un1.ip6_un1_hlim = 32;

            write_bytes((const char *)&HDR_IPv6, sizeof(HDR_IPv6));

            /* initialize pseudo ipv6 header for checksum calculation */

            pseudoh6.src_addr6  = HDR_IPv6.ip6_src;

            pseudoh6.dst_addr6  = HDR_IPv6.ip6_dst;

            pseudoh6.zero       = 0;

            pseudoh6.protocol   = (guint8) hdr_ip_proto;

            ihatemacros         = g_ntohs(HDR_IPv6.ip6_ctlun.ip6_un1.ip6_un1_plen);

            pseudoh.length      = g_htons(length - ihatemacros + sizeof(HDR_UDP));

        }

        if(!hdr_ipv6) {

            /* initialize pseudo header for checksum calculation */

            pseudoh.src_addr    = HDR_IP.src_addr;

            pseudoh.dest_addr   = HDR_IP.dest_addr;

            pseudoh.zero        = 0;

            pseudoh.protocol    = (guint8) hdr_ip_proto;

            pseudoh.length      = g_htons(length - header_length + sizeof(HDR_UDP));

        }

        /* Write UDP header */

        if (hdr_udp) {

            guint16 x16;

            guint32 u;

            /* initialize the UDP header */

            HDR_UDP.source_port = g_htons(hdr_src_port);

            HDR_UDP.dest_port = g_htons(hdr_dest_port);

            HDR_UDP.length      = pseudoh.length;

            HDR_UDP.checksum = 0;

            /* Note: g_ntohs()/g_htons() macro arg may be eval'd twice so calc value before invoking macro */

            x16  = hdr_ipv6 ? in_checksum(&pseudoh6, sizeof(pseudoh6)) : in_checksum(&pseudoh, sizeof(pseudoh));

            u    = g_ntohs(x16);

            x16  = in_checksum(&HDR_UDP, sizeof(HDR_UDP));

            u   += g_ntohs(x16);

            x16  = in_checksum(packet_buf + header_length, length - header_length);

            u   += g_ntohs(x16);

            x16  = (u & 0xffff) + (u>>16);

            HDR_UDP.checksum = g_htons(x16);

            if (HDR_UDP.checksum == 0) /* differentiate between 'none' and 0 */

                HDR_UDP.checksum = g_htons(1);

            write_bytes((const char *)&HDR_UDP, sizeof(HDR_UDP));

        }

        /* Write TCP header */

        if (hdr_tcp) {

            guint16 x16;

            guint32 u;

             /* initialize pseudo header for checksum calculation */

            pseudoh.src_addr    = HDR_IP.src_addr;

            pseudoh.dest_addr   = HDR_IP.dest_addr;

            pseudoh.zero        = 0;

            pseudoh.protocol    = (guint8) hdr_ip_proto;

            pseudoh.length      = g_htons(length - header_length + sizeof(HDR_TCP));

            /* initialize the TCP header */

            HDR_TCP.source_port = g_htons(hdr_src_port);

            HDR_TCP.dest_port = g_htons(hdr_dest_port);

            /* HDR_TCP.seq_num already correct */

            HDR_TCP.window = g_htons(0x2000);

            HDR_TCP.checksum = 0;

            /* Note: g_ntohs()/g_htons() macro arg may be eval'd twice so calc value before invoking macro */

            x16  = in_checksum(&pseudoh, sizeof(pseudoh));

            u    = g_ntohs(x16);

            x16  = in_checksum(&HDR_TCP, sizeof(HDR_TCP));

            u   += g_ntohs(x16);

            x16  = in_checksum(packet_buf + header_length, length - header_length);

            u   += g_ntohs(x16);

            x16  = (u & 0xffff) + (u>>16);

            HDR_TCP.checksum = g_htons(x16);

            if (HDR_TCP.checksum == 0) /* differentiate between 'none' and 0 */

                HDR_TCP.checksum = g_htons(1);

            write_bytes((const char *)&HDR_TCP, sizeof(HDR_TCP));

            HDR_TCP.seq_num = g_ntohl(HDR_TCP.seq_num) + length - header_length;

            HDR_TCP.seq_num = g_htonl(HDR_TCP.seq_num);

        }

        /* Compute DATA chunk header */

        if (hdr_data_chunk) {

            hdr_data_chunk_bits = 0;

            if (packet_start == 0) {

                hdr_data_chunk_bits |= 0x02;

            }

            if (!cont) {

                hdr_data_chunk_bits |= 0x01;

            }

            HDR_DATA_CHUNK.type   = hdr_data_chunk_type;

            HDR_DATA_CHUNK.bits   = hdr_data_chunk_bits;

            HDR_DATA_CHUNK.length = g_htons(length - header_length + sizeof(HDR_DATA_CHUNK));

            HDR_DATA_CHUNK.tsn    = g_htonl(hdr_data_chunk_tsn);

            HDR_DATA_CHUNK.sid    = g_htons(hdr_data_chunk_sid);

            HDR_DATA_CHUNK.ssn    = g_htons(hdr_data_chunk_ssn);

            HDR_DATA_CHUNK.ppid   = g_htonl(hdr_data_chunk_ppid);

            hdr_data_chunk_tsn++;

            if (!cont) {

                hdr_data_chunk_ssn++;

            }

        }

        /* Write SCTP common header */

        if (hdr_sctp) {

            guint32 zero = 0;

            HDR_SCTP.src_port  = g_htons(hdr_sctp_src);

            HDR_SCTP.dest_port = g_htons(hdr_sctp_dest);

            HDR_SCTP.tag       = g_htonl(hdr_sctp_tag);

            HDR_SCTP.checksum  = g_htonl(0);

            HDR_SCTP.checksum  = crc32c((guint8 *)&HDR_SCTP, sizeof(HDR_SCTP), ~0L);

            if (hdr_data_chunk) {

                HDR_SCTP.checksum  = crc32c((guint8 *)&HDR_DATA_CHUNK, sizeof(HDR_DATA_CHUNK), HDR_SCTP.checksum);

                HDR_SCTP.checksum  = crc32c((guint8 *)packet_buf + header_length, length - header_length, HDR_SCTP.checksum);

                HDR_SCTP.checksum  = crc32c((guint8 *)&zero, padding_length, HDR_SCTP.checksum);

            } else {

                HDR_SCTP.checksum  = crc32c((guint8 *)packet_buf + header_length, length - header_length, HDR_SCTP.checksum);

            }

            HDR_SCTP.checksum = finalize_crc32c(HDR_SCTP.checksum);

            HDR_SCTP.checksum  = g_htonl(HDR_SCTP.checksum);

            write_bytes((const char *)&HDR_SCTP, sizeof(HDR_SCTP));

        }

        /* Write DATA chunk header */

        if (hdr_data_chunk) {

            write_bytes((const char *)&HDR_DATA_CHUNK, sizeof(HDR_DATA_CHUNK));

        }

        /* Reset curr_offset, since we now write the trailers */

        curr_offset = length;

        /* Write DATA chunk padding */

        if (hdr_data_chunk && (padding_length > 0)) {

            memset(tempbuf, 0, padding_length);

            write_bytes((const char *)&tempbuf, padding_length);

            length += padding_length;

        }

        /* Write Ethernet trailer */

        if (hdr_ethernet && (length < 60)) {

            memset(tempbuf, 0, 60 - length);

            write_bytes((const char *)&tempbuf, 60 - length);

            length = 60;

        }

        if (use_pcapng) {

            success = libpcap_write_enhanced_packet_block(libpcap_write_to_file, output_file,

                                                          NULL,

                                                          ts_sec, ts_usec,

                                                          length, length,

                                                          0,

                                                          1000000,

                                                          packet_buf, direction,

                                                          &bytes_written, &err);

        } else {

            success = libpcap_write_packet(libpcap_write_to_file, output_file,

                                           ts_sec, ts_usec,

                                           length, length,

                                           packet_buf,

                                           &bytes_written, &err);

        }

        if (!success) {

            fprintf(stderr, "File write error [%s] : %s\n",

                    output_filename, g_strerror(err));

            exit(-1);

        }

        if (ts_fmt == NULL) {

            /* fake packet counter */

            ts_usec++;

        }

        if (!quiet) {

            fprintf(stderr, "Wrote packet of %u bytes.\n", length);

        }

        num_packets_written ++;

    }

    packet_start += curr_offset - header_length;

    curr_offset = header_length;

    return;

}

/*----------------------------------------------------------------------

 * Write file header and trailer

 */

static void

write_file_header (void)

{

    int err;

    gboolean success;

    if (use_pcapng) {

#ifdef SVNVERSION

        const char *appname = "text2pcap (" SVNVERSION " from " SVNPATH ")";

#else

        const char *appname = "text2pcap";

#endif

        char comment[100];

        g_snprintf(comment, sizeof(comment), "Generated from input file %s.", input_filename);

        success = libpcap_write_session_header_block(libpcap_write_to_file, output_file,

                                                     comment,

                                                     NULL,

                                                     NULL,

                                                     appname,

                                                     -1,

                                                     &bytes_written,

                                                     &err);

        if (success) {

            success = libpcap_write_interface_description_block(libpcap_write_to_file, output_file,

                                                                NULL,

                                                                NULL,

                                                                NULL,

                                                                "",

                                                                NULL,

                                                                pcap_link_type,

                                                                PCAP_SNAPLEN,

                                                                &bytes_written,

                                                                0,

                                                                6,

                                                                &err);

        }

    } else {

        success = libpcap_write_file_header(libpcap_write_to_file, output_file, pcap_link_type, PCAP_SNAPLEN,

                                            FALSE, &bytes_written, &err);

    }

    if (!success) {

        fprintf(stderr, "File write error [%s] : %s\n",

                output_filename, g_strerror(err));

        exit(-1);

    }

}

static void

write_file_trailer (void)

{

    int err;

    gboolean success;

    if (use_pcapng) {

        success = libpcap_write_interface_statistics_block(libpcap_write_to_file, output_file,

                                                           0,

                                                           &bytes_written,

                                                           "Counters provided by text2pcap",

                                                           0,

                                                           0,

                                                           num_packets_written,

                                                           num_packets_written - num_packets_written,

                                                           &err);

    } else {

        success = TRUE;

    }

    if (!success) {

        fprintf(stderr, "File write error [%s] : %s\n",

                output_filename, g_strerror(err));

        exit(-1);

    }

   return;

}

/*----------------------------------------------------------------------

 * Append a token to the packet preamble.

 */

static void

append_to_preamble(char *str)

{

    size_t toklen;

    if (packet_preamble_len != 0) {