sys/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  * $FreeBSD: src/sys/netinet/tcp.h,v 1.13.2.3 2001/03/01 22:08:42 jlemon Exp $
  35  * $DragonFly: src/sys/netinet/tcp.h,v 1.7 2006/05/20 02:42:12 dillon Exp $
  36  */
  37
  38 #ifndef _NETINET_TCP_H_
  39 #define _NETINET_TCP_H_
  40
  41 #ifndef _SYS_TYPES_H_
  42 #include <sys/types.h>
  43 #endif
  44 #ifndef _MACHINE_ENDIAN_H_
  45 #include <machine/endian.h>
  46 #endif
  47
  48 typedef u_int32_t tcp_seq;
  49 typedef int32_t   tcp_seq_diff_t;
  50
  51 #define tcp6_seq        tcp_seq /* for KAME src sync over BSD*'s */
  52 #define tcp6hdr         tcphdr  /* for KAME src sync over BSD*'s */
  53
  54 /*
  55  * TCP header.
  56  * Per RFC 793, September, 1981.
  57  */
  58 struct tcphdr {
  59         u_short th_sport;               /* source port */
  60         u_short th_dport;               /* destination port */
  61         tcp_seq th_seq;                 /* sequence number */
  62         tcp_seq th_ack;                 /* acknowledgement number */
  63 #if _BYTE_ORDER == _LITTLE_ENDIAN
  64         u_int   th_x2:4,                /* (unused) */
  65                 th_off:4;               /* data offset */
  66 #elif _BYTE_ORDER == _BIG_ENDIAN
  67         u_int   th_off:4,               /* data offset */
  68                 th_x2:4;                /* (unused) */
  69 #else
  70 #error "Byte order not implemented"
  71 #endif
  72         u_char  th_flags;
  73 #define TH_FIN  0x01
  74 #define TH_SYN  0x02
  75 #define TH_RST  0x04
  76 #define TH_PUSH 0x08
  77 #define TH_ACK  0x10
  78 #define TH_URG  0x20
  79 #define TH_ECE  0x40
  80 #define TH_CWR  0x80
  81 #define TH_FLAGS        (TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG|TH_ECE|TH_CWR)
  82
  83         u_short th_win;                 /* window */
  84         u_short th_sum;                 /* checksum */
  85         u_short th_urp;                 /* urgent pointer */
  86 };
  87
  88 #define TCPOPT_EOL              0
  89 #define TCPOPT_NOP              1
  90 #define TCPOPT_2NOPs            (TCPOPT_NOP << 24 | TCPOPT_NOP << 16)
  91 #define TCPOPT_MAXSEG           2
  92 #define    TCPOLEN_MAXSEG               4
  93 #define TCPOPT_WINDOW           3
  94 #define    TCPOLEN_WINDOW               3
  95 #define TCPOPT_SACK_PERMITTED   4
  96 #define    TCPOLEN_SACK_PERMITTED               2
  97 #define    TCPOPT_SACK_PERMITTED_ALIGNED        \
  98     (TCPOPT_2NOPs | TCPOPT_SACK_PERMITTED << 8 | TCPOLEN_SACK_PERMITTED)
  99 #define    TCPOLEN_SACK_PERMITTED_ALIGNED       4
 100 #define TCPOPT_SACK             5
 101 #define    TCPOLEN_SACK         2
 102 #define    TCPOLEN_SACK_BLOCK   8
 103 #define TCPOPT_SACK_ALIGNED     (TCPOPT_2NOPs | TCPOPT_SACK << 8)
 104 #define    TCPOLEN_SACK_ALIGNED 4
 105 #define TCPOPT_TIMESTAMP        8
 106 #define    TCPOLEN_TIMESTAMP            10
 107 #define    TCPOLEN_TSTAMP_APPA          (TCPOLEN_TIMESTAMP+2) /* appendix A */
 108 #define    TCPOPT_TSTAMP_HDR            \
 109     (TCPOPT_2NOPs | TCPOPT_TIMESTAMP << 8 | TCPOLEN_TIMESTAMP)
 110 #define TCPOPT_CC               11              /* CC options: RFC-1644 */
 111 #define TCPOPT_CCNEW            12
 112 #define TCPOPT_CCECHO           13
 113
 114 /*
 115  * Default maximum segment size for TCP.
 116  * With an IP MSS of 576, this is 536,
 117  * but 512 is probably more convenient.
 118  * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
 119  */
 120 #define TCP_MSS 512
 121
 122 /*
 123  * TCP_MINMSS is defined to be 256 which is fine for the smallest
 124  * link MTU (296 bytes, SLIP interface) in the Internet.
 125  * However it is very unlikely to come across such low MTU interfaces
 126  * these days (anno dato 2003).
 127  * Probably it can be set to 512 without ill effects. But we play safe.
 128  * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments.
 129  * Setting this to "0" disables the minmss check.
 130  */
 131 #define TCP_MINMSS 256
 132
 133 /*
 134  * Default maximum segment size for TCP6.
 135  * With an IP6 MSS of 1280, this is 1220,
 136  * but 1024 is probably more convenient. (xxx kazu in doubt)
 137  * This should be defined as MIN(1024, IP6_MSS - sizeof (struct tcpip6hdr))
 138  *
 139  * NOTE: TCP_MIN_WINSHIFT is used when negotiating window scaling.  Larger
 140  *       values are possible but apparently some firewires blows up if
 141  *       values larger then 5 are used, so use 5.
 142  */
 143 #define TCP6_MSS        1024
 144
 145 #define TCP_MAXWIN              65535   /* max value for (unscaled) window */
 146
 147 #define TCP_MIN_WINSHIFT        5       /* requested minimum (x32) */
 148 #define TCP_MAX_WINSHIFT        14      /* maximum window shift */
 149
 150 #define TCP_MAXBURST            4       /* maximum segments in a burst */
 151
 152 #define TCP_MAXHLEN     (0xf<<2)        /* max length of header in bytes */
 153 #define TCP_MAXOLEN     (TCP_MAXHLEN - sizeof(struct tcphdr))
 154                                         /* max space left for options */
 155
 156 /*
 157  * User-settable options (used with setsockopt).
 158  */
 159 #define TCP_NODELAY     0x01    /* don't delay send to coalesce packets */
 160 #define TCP_MAXSEG      0x02    /* set maximum segment size */
 161 #define TCP_NOPUSH      0x04    /* don't push last block of write */
 162 #define TCP_NOOPT       0x08    /* don't use TCP options */
 163
 164 #endif