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   1 /* @(#) $Header: /tcpdump/master/tcpdump/ip.h,v 1.2 2000-09-24 07:40:45 guy Exp $ (LBL) */
   2 /*
   3  * Copyright (c) 1982, 1986, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. All advertising materials mentioning features or use of this software
  15  *    must display the following acknowledgement:
  16  *      This product includes software developed by the University of
  17  *      California, Berkeley and its contributors.
  18  * 4. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      @(#)ip.h        8.2 (Berkeley) 6/1/94
  35  */
  36
  37 #ifndef BYTE_ORDER
  38 #define LITTLE_ENDIAN   1234    /* least-significant byte first (vax, pc) */
  39 #define BIG_ENDIAN      4321    /* most-significant byte first (IBM, net) */
  40 #define PDP_ENDIAN      3412    /* LSB first in word, MSW first in long (pdp)*/
  41
  42 #ifdef WORDS_BIGENDIAN
  43 #define BYTE_ORDER      BIG_ENDIAN
  44 #else
  45 #define BYTE_ORDER      LITTLE_ENDIAN
  46 #endif /* WORDS_BIGENDIAN */
  47 #endif /* BYTE_ORDER */
  48
  49 #if !defined(BYTE_ORDER) || \
  50     (BYTE_ORDER != BIG_ENDIAN && BYTE_ORDER != LITTLE_ENDIAN && \
  51     BYTE_ORDER != PDP_ENDIAN)
  52         /* you must determine what the correct bit order is for
  53          * your compiler - the next line is an intentional error
  54          * which will force your compiles to bomb until you fix
  55          * the above macros.
  56          */
  57   #error "Undefined or invalid BYTE_ORDER";
  58 #endif
  59
  60 /*
  61  * Definitions for internet protocol version 4.
  62  * Per RFC 791, September 1981.
  63  */
  64 #define IPVERSION       4
  65
  66 /*
  67  * Structure of an internet header, naked of options.
  68  *
  69  * We declare ip_len and ip_off to be short, rather than u_short
  70  * pragmatically since otherwise unsigned comparisons can result
  71  * against negative integers quite easily, and fail in subtle ways.
  72  */
  73 struct ip {
  74 #if BYTE_ORDER == LITTLE_ENDIAN
  75         u_char  ip_hl:4,                /* header length */
  76                 ip_v:4;                 /* version */
  77 #endif
  78 #if BYTE_ORDER == BIG_ENDIAN
  79         u_char  ip_v:4,                 /* version */
  80                 ip_hl:4;                /* header length */
  81 #endif
  82         u_char  ip_tos;                 /* type of service */
  83         short   ip_len;                 /* total length */
  84         u_short ip_id;                  /* identification */
  85         short   ip_off;                 /* fragment offset field */
  86 #define IP_DF 0x4000                    /* dont fragment flag */
  87 #define IP_MF 0x2000                    /* more fragments flag */
  88 #define IP_OFFMASK 0x1fff               /* mask for fragmenting bits */
  89         u_char  ip_ttl;                 /* time to live */
  90         u_char  ip_p;                   /* protocol */
  91         u_short ip_sum;                 /* checksum */
  92         struct  in_addr ip_src,ip_dst;  /* source and dest address */
  93 };
  94
  95 #define IP_MAXPACKET    65535           /* maximum packet size */
  96
  97 /*
  98  * Definitions for IP type of service (ip_tos)
  99  */
 100 #define IPTOS_LOWDELAY          0x10
 101 #define IPTOS_THROUGHPUT        0x08
 102 #define IPTOS_RELIABILITY       0x04
 103
 104 /*
 105  * Definitions for IP precedence (also in ip_tos) (hopefully unused)
 106  */
 107 #define IPTOS_PREC_NETCONTROL           0xe0
 108 #define IPTOS_PREC_INTERNETCONTROL      0xc0
 109 #define IPTOS_PREC_CRITIC_ECP           0xa0
 110 #define IPTOS_PREC_FLASHOVERRIDE        0x80
 111 #define IPTOS_PREC_FLASH                0x60
 112 #define IPTOS_PREC_IMMEDIATE            0x40
 113 #define IPTOS_PREC_PRIORITY             0x20
 114 #define IPTOS_PREC_ROUTINE              0x00
 115
 116 /*
 117  * Definitions for options.
 118  */
 119 #define IPOPT_COPIED(o)         ((o)&0x80)
 120 #define IPOPT_CLASS(o)          ((o)&0x60)
 121 #define IPOPT_NUMBER(o)         ((o)&0x1f)
 122
 123 #define IPOPT_CONTROL           0x00
 124 #define IPOPT_RESERVED1         0x20
 125 #define IPOPT_DEBMEAS           0x40
 126 #define IPOPT_RESERVED2         0x60
 127
 128 #define IPOPT_EOL               0               /* end of option list */
 129 #define IPOPT_NOP               1               /* no operation */
 130
 131 #define IPOPT_RR                7               /* record packet route */
 132 #define IPOPT_TS                68              /* timestamp */
 133 #define IPOPT_SECURITY          130             /* provide s,c,h,tcc */
 134 #define IPOPT_LSRR              131             /* loose source route */
 135 #define IPOPT_SATID             136             /* satnet id */
 136 #define IPOPT_SSRR              137             /* strict source route */
 137
 138 /*
 139  * Offsets to fields in options other than EOL and NOP.
 140  */
 141 #define IPOPT_OPTVAL            0               /* option ID */
 142 #define IPOPT_OLEN              1               /* option length */
 143 #define IPOPT_OFFSET            2               /* offset within option */
 144 #define IPOPT_MINOFF            4               /* min value of above */
 145
 146 /*
 147  * Time stamp option structure.
 148  */
 149 struct  ip_timestamp {
 150         u_char  ipt_code;               /* IPOPT_TS */
 151         u_char  ipt_len;                /* size of structure (variable) */
 152         u_char  ipt_ptr;                /* index of current entry */
 153 #if BYTE_ORDER == LITTLE_ENDIAN
 154         u_char  ipt_flg:4,              /* flags, see below */
 155                 ipt_oflw:4;             /* overflow counter */
 156 #endif
 157 #if BYTE_ORDER == BIG_ENDIAN
 158         u_char  ipt_oflw:4,             /* overflow counter */
 159                 ipt_flg:4;              /* flags, see below */
 160 #endif
 161         union ipt_timestamp {
 162                 n_long  ipt_time[1];
 163                 struct  ipt_ta {
 164                         struct in_addr ipt_addr;
 165                         n_long ipt_time;
 166                 } ipt_ta[1];
 167         } ipt_timestamp;
 168 };
 169
 170 /* flag bits for ipt_flg */
 171 #define IPOPT_TS_TSONLY         0               /* timestamps only */
 172 #define IPOPT_TS_TSANDADDR      1               /* timestamps and addresses */
 173 #define IPOPT_TS_PRESPEC        3               /* specified modules only */
 174
 175 /* bits for security (not byte swapped) */
 176 #define IPOPT_SECUR_UNCLASS     0x0000
 177 #define IPOPT_SECUR_CONFID      0xf135
 178 #define IPOPT_SECUR_EFTO        0x789a
 179 #define IPOPT_SECUR_MMMM        0xbc4d
 180 #define IPOPT_SECUR_RESTR       0xaf13
 181 #define IPOPT_SECUR_SECRET      0xd788
 182 #define IPOPT_SECUR_TOPSECRET   0x6bc5
 183
 184 /*
 185  * Internet implementation parameters.
 186  */
 187 #define MAXTTL          255             /* maximum time to live (seconds) */
 188 #define IPDEFTTL        64              /* default ttl, from RFC 1340 */
 189 #define IPFRAGTTL       60              /* time to live for frags, slowhz */
 190 #define IPTTLDEC        1               /* subtracted when forwarding */
 191
 192 #define IP_MSS          576             /* default maximum segment size */