The Tcpdump Group git mirrors - tcpdump/blob - linux-include/netinet/tcp.h

   1 /*
   2  * Copyright (c) 1982, 1986, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  *      @(#)tcp.h       8.1 (Berkeley) 6/10/93
  34  */
  35
  36 typedef u_int   tcp_seq;
  37 /*
  38  * TCP header.
  39  * Per RFC 793, September, 1981.
  40  */
  41 struct tcphdr {
  42         u_short th_sport;               /* source port */
  43         u_short th_dport;               /* destination port */
  44         tcp_seq th_seq;                 /* sequence number */
  45         tcp_seq th_ack;                 /* acknowledgement number */
  46 #if BYTE_ORDER == LITTLE_ENDIAN
  47         u_char  th_x2:4,                /* (unused) */
  48                 th_off:4;               /* data offset */
  49 #endif
  50 #if BYTE_ORDER == BIG_ENDIAN
  51         u_char  th_off:4,               /* data offset */
  52                 th_x2:4;                /* (unused) */
  53 #endif
  54         u_char  th_flags;
  55 #define TH_FIN  0x01
  56 #define TH_SYN  0x02
  57 #define TH_RST  0x04
  58 #define TH_PUSH 0x08
  59 #define TH_ACK  0x10
  60 #define TH_URG  0x20
  61         u_short th_win;                 /* window */
  62         u_short th_sum;                 /* checksum */
  63         u_short th_urp;                 /* urgent pointer */
  64 };
  65
  66 #define TCPOPT_EOL              0
  67 #define TCPOPT_NOP              1
  68 #define TCPOPT_MAXSEG           2
  69 #define    TCPOLEN_MAXSEG               4
  70 #define TCPOPT_WINDOW           3
  71 #define    TCPOLEN_WINDOW               3
  72 #define TCPOPT_SACK_PERMITTED   4               /* Experimental */
  73 #define    TCPOLEN_SACK_PERMITTED       2
  74 #define TCPOPT_SACK             5               /* Experimental */
  75 #define TCPOPT_TIMESTAMP        8
  76 #define    TCPOLEN_TIMESTAMP            10
  77 #define    TCPOLEN_TSTAMP_APPA          (TCPOLEN_TIMESTAMP+2) /* appendix A */
  78
  79 #define TCPOPT_TSTAMP_HDR       \
  80     (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP)
  81
  82 /*
  83  * Default maximum segment size for TCP.
  84  * With an IP MSS of 576, this is 536,
  85  * but 512 is probably more convenient.
  86  * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
  87  */
  88 #define TCP_MSS 512
  89
  90 #define TCP_MAXWIN      65535   /* largest value for (unscaled) window */
  91
  92 #define TCP_MAX_WINSHIFT        14      /* maximum window shift */
  93
  94 /*
  95  * User-settable options (used with setsockopt).
  96  */
  97 #ifndef TCP_NODELAY
  98 #define TCP_NODELAY     0x01    /* don't delay send to coalesce packets */
  99 #endif
 100 #ifndef TCP_MAXSEG
 101 #define TCP_MAXSEG      0x02    /* set maximum segment size */
 102 #endif