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 typedef u_int32_t tcp_cc;               /* connection count per rfc1644 */
  51
  52 #define tcp6_seq        tcp_seq /* for KAME src sync over BSD*'s */
  53 #define tcp6hdr         tcphdr  /* for KAME src sync over BSD*'s */
  54
  55 /*
  56  * TCP header.
  57  * Per RFC 793, September, 1981.
  58  */
  59 struct tcphdr {
  60         u_short th_sport;               /* source port */
  61         u_short th_dport;               /* destination port */
  62         tcp_seq th_seq;                 /* sequence number */
  63         tcp_seq th_ack;                 /* acknowledgement number */
  64 #if _BYTE_ORDER == _LITTLE_ENDIAN
  65         u_int   th_x2:4,                /* (unused) */
  66                 th_off:4;               /* data offset */
  67 #elif _BYTE_ORDER == _BIG_ENDIAN
  68         u_int   th_off:4,               /* data offset */
  69                 th_x2:4;                /* (unused) */
  70 #else
  71 #error "Byte order not implemented"
  72 #endif
  73         u_char  th_flags;
  74 #define TH_FIN  0x01
  75 #define TH_SYN  0x02
  76 #define TH_RST  0x04
  77 #define TH_PUSH 0x08
  78 #define TH_ACK  0x10
  79 #define TH_URG  0x20
  80 #define TH_ECE  0x40
  81 #define TH_CWR  0x80
  82 #define TH_FLAGS        (TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG|TH_ECE|TH_CWR)
  83
  84         u_short th_win;                 /* window */
  85         u_short th_sum;                 /* checksum */
  86         u_short th_urp;                 /* urgent pointer */
  87 };
  88
  89 #define TCPOPT_EOL              0
  90 #define TCPOPT_NOP              1
  91 #define TCPOPT_2NOPs            (TCPOPT_NOP << 24 | TCPOPT_NOP << 16)
  92 #define TCPOPT_MAXSEG           2
  93 #define    TCPOLEN_MAXSEG               4
  94 #define TCPOPT_WINDOW           3
  95 #define    TCPOLEN_WINDOW               3
  96 #define TCPOPT_SACK_PERMITTED   4
  97 #define    TCPOLEN_SACK_PERMITTED               2
  98 #define    TCPOPT_SACK_PERMITTED_ALIGNED        \
  99     (TCPOPT_2NOPs | TCPOPT_SACK_PERMITTED << 8 | TCPOLEN_SACK_PERMITTED)
 100 #define    TCPOLEN_SACK_PERMITTED_ALIGNED       4
 101 #define TCPOPT_SACK             5
 102 #define    TCPOLEN_SACK         2
 103 #define    TCPOLEN_SACK_BLOCK   8
 104 #define TCPOPT_SACK_ALIGNED     (TCPOPT_2NOPs | TCPOPT_SACK << 8)
 105 #define    TCPOLEN_SACK_ALIGNED 4
 106 #define TCPOPT_TIMESTAMP        8
 107 #define    TCPOLEN_TIMESTAMP            10
 108 #define    TCPOLEN_TSTAMP_APPA          (TCPOLEN_TIMESTAMP+2) /* appendix A */
 109 #define    TCPOPT_TSTAMP_HDR            \
 110     (TCPOPT_2NOPs | TCPOPT_TIMESTAMP << 8 | TCPOLEN_TIMESTAMP)
 111 #define TCPOPT_CC               11              /* CC options: RFC-1644 */
 112 #define TCPOPT_CCNEW            12
 113 #define TCPOPT_CCECHO           13
 114 #define    TCPOLEN_CC                   6
 115 #define    TCPOLEN_CC_APPA              (TCPOLEN_CC+2)
 116 #define    TCPOPT_CC_HDR(ccopt)         \
 117     (TCPOPT_2NOPs | (ccopt) << 8 | TCPOLEN_CC)
 118
 119 /*
 120  * Default maximum segment size for TCP.
 121  * With an IP MSS of 576, this is 536,
 122  * but 512 is probably more convenient.
 123  * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
 124  * The modern consensus is that 1500 is a safe MTU to use for the Internet.
 125  */
 126 #define TCP_MSS 1460
 127
 128 /*
 129  * TCP_MINMSS is defined to be 256 which is fine for the smallest
 130  * link MTU (296 bytes, SLIP interface) in the Internet.
 131  * However it is very unlikely to come across such low MTU interfaces
 132  * these days (anno dato 2003).
 133  * Probably it can be set to 512 without ill effects. But we play safe.
 134  * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments.
 135  * Setting this to "0" disables the minmss check.
 136  */
 137 #define TCP_MINMSS 256
 138
 139 /*
 140  * Default maximum segment size for TCP6.
 141  * With an IP6 MSS of 1280, this is 1220,
 142  * but 1024 is probably more convenient. (xxx kazu in doubt)
 143  * This should be defined as MIN(1024, IP6_MSS - sizeof (struct tcpip6hdr))
 144  *
 145  * NOTE: TCP_MIN_WINSHIFT is used when negotiating window scaling.  Larger
 146  *       values are possible but apparently some firewires blows up if
 147  *       values larger then 5 are used, so use 5.
 148  */
 149 #define TCP6_MSS        1024
 150
 151 #define TCP_MAXWIN              65535   /* max value for (unscaled) window */
 152 #define TTCP_CLIENT_SND_WND     4096    /* dflt send window for T/TCP client */
 153
 154 #define TCP_MIN_WINSHIFT        5       /* requested minimum (x32) */
 155 #define TCP_MAX_WINSHIFT        14      /* maximum window shift */
 156
 157 #define TCP_MAXBURST            4       /* maximum segments in a burst */
 158
 159 #define TCP_MAXHLEN     (0xf<<2)        /* max length of header in bytes */
 160 #define TCP_MAXOLEN     (TCP_MAXHLEN - sizeof(struct tcphdr))
 161                                         /* max space left for options */
 162
 163 /*
 164  * User-settable options (used with setsockopt).
 165  */
 166 #define TCP_NODELAY     0x01    /* don't delay send to coalesce packets */
 167 #define TCP_MAXSEG      0x02    /* set maximum segment size */
 168 #define TCP_NOPUSH      0x04    /* don't push last block of write */
 169 #define TCP_NOOPT       0x08    /* don't use TCP options */
 170
 171 #endif