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. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)tcp.h       8.1 (Berkeley) 6/10/93
  30  * $FreeBSD: src/sys/netinet/tcp.h,v 1.13.2.3 2001/03/01 22:08:42 jlemon Exp $
  31  */
  32
  33 #ifndef _NETINET_TCP_H_
  34 #define _NETINET_TCP_H_
  35
  36 #include <sys/cdefs.h>
  37
  38 #if __BSD_VISIBLE
  39
  40 #include <sys/types.h>
  41
  42 typedef u_int32_t       tcp_seq;
  43 typedef int32_t         tcp_seq_diff_t;
  44
  45 #define tcp6_seq        tcp_seq /* for KAME src sync over BSD*'s */
  46 #define tcp6hdr         tcphdr  /* for KAME src sync over BSD*'s */
  47
  48 /*
  49  * TCP header.
  50  * Per RFC 793, September, 1981.
  51  */
  52 struct tcphdr {
  53         u_short th_sport;               /* source port */
  54         u_short th_dport;               /* destination port */
  55         tcp_seq th_seq;                 /* sequence number */
  56         tcp_seq th_ack;                 /* acknowledgement number */
  57 #if _BYTE_ORDER == _LITTLE_ENDIAN
  58         u_int   th_x2:4,                /* (unused) */
  59                 th_off:4;               /* data offset */
  60 #elif _BYTE_ORDER == _BIG_ENDIAN
  61         u_int   th_off:4,               /* data offset */
  62                 th_x2:4;                /* (unused) */
  63 #else
  64 #error "Byte order not implemented"
  65 #endif
  66         u_char  th_flags;
  67 #define TH_FIN  0x01
  68 #define TH_SYN  0x02
  69 #define TH_RST  0x04
  70 #define TH_PUSH 0x08
  71 #define TH_ACK  0x10
  72 #define TH_URG  0x20
  73 #define TH_ECE  0x40
  74 #define TH_CWR  0x80
  75 #define TH_FLAGS        (TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG|TH_ECE|TH_CWR)
  76
  77         u_short th_win;                 /* window */
  78         u_short th_sum;                 /* checksum */
  79         u_short th_urp;                 /* urgent pointer */
  80 };
  81
  82 #define TCPOPT_EOL              0
  83 #define TCPOPT_NOP              1
  84 #define TCPOPT_2NOPs            (TCPOPT_NOP << 24 | TCPOPT_NOP << 16)
  85 #define TCPOPT_MAXSEG           2
  86 #define    TCPOLEN_MAXSEG               4
  87 #define TCPOPT_WINDOW           3
  88 #define    TCPOLEN_WINDOW               3
  89 #define TCPOPT_SACK_PERMITTED   4
  90 #define    TCPOLEN_SACK_PERMITTED               2
  91 #define    TCPOPT_SACK_PERMITTED_ALIGNED        \
  92     (TCPOPT_2NOPs | TCPOPT_SACK_PERMITTED << 8 | TCPOLEN_SACK_PERMITTED)
  93 #define    TCPOLEN_SACK_PERMITTED_ALIGNED       4
  94 #define TCPOPT_SACK             5
  95 #define    TCPOLEN_SACK         2
  96 #define    TCPOLEN_SACK_BLOCK   8
  97 #define TCPOPT_SACK_ALIGNED     (TCPOPT_2NOPs | TCPOPT_SACK << 8)
  98 #define    TCPOLEN_SACK_ALIGNED 4
  99 #define TCPOPT_TIMESTAMP        8
 100 #define    TCPOLEN_TIMESTAMP            10
 101 #define    TCPOLEN_TSTAMP_APPA          (TCPOLEN_TIMESTAMP+2) /* appendix A */
 102 #define    TCPOPT_TSTAMP_HDR            \
 103     (TCPOPT_2NOPs | TCPOPT_TIMESTAMP << 8 | TCPOLEN_TIMESTAMP)
 104 #define TCPOPT_CC               11              /* CC options: RFC-1644 */
 105 #define TCPOPT_CCNEW            12
 106 #define TCPOPT_CCECHO           13
 107 #define TCPOPT_SIGNATURE                19      /* Keyed MD5: RFC 2385 */
 108 #define TCPOLEN_SIGNATURE               18
 109
 110 /*
 111  * Default maximum segment size for TCP.
 112  * With an IP MSS of 576, this is 536,
 113  * but 512 is probably more convenient.
 114  * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
 115  */
 116 #define TCP_MSS 512
 117
 118 /*
 119  * TCP_MINMSS is defined to be 256 which is fine for the smallest
 120  * link MTU (296 bytes, SLIP interface) in the Internet.
 121  * However it is very unlikely to come across such low MTU interfaces
 122  * these days (anno dato 2003).
 123  * Probably it can be set to 512 without ill effects. But we play safe.
 124  * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments.
 125  * Setting this to "0" disables the minmss check.
 126  */
 127 #define TCP_MINMSS 256
 128
 129 /*
 130  * Default maximum segment size for TCP6.
 131  * With an IP6 MSS of 1280, this is 1220,
 132  * but 1024 is probably more convenient. (xxx kazu in doubt)
 133  * This should be defined as MIN(1024, IP6_MSS - sizeof (struct tcpip6hdr))
 134  *
 135  * NOTE: TCP_MIN_WINSHIFT is used when negotiating window scaling.  Larger
 136  *       values are possible but apparently some firewires blows up if
 137  *       values larger then 5 are used, so use 5.
 138  */
 139 #define TCP6_MSS        1024
 140
 141 #define TCP_MAXWIN              65535   /* max value for (unscaled) window */
 142
 143 #define TCP_MIN_WINSHIFT        5       /* requested minimum (x32) */
 144 #define TCP_MAX_WINSHIFT        14      /* maximum window shift */
 145
 146 #define TCP_MAXBURST            4       /* maximum segments in a burst */
 147
 148 #define TCP_MAXHLEN     (0xf<<2)        /* max length of header in bytes */
 149 #define TCP_MAXOLEN     (TCP_MAXHLEN - sizeof(struct tcphdr))
 150                                         /* max space left for options */
 151 #endif /* __BSD_VISIBLE */
 152
 153 /*
 154  * User-settable options (used with setsockopt).
 155  */
 156 #define TCP_NODELAY     0x01    /* don't delay send to coalesce packets */
 157 #if __BSD_VISIBLE
 158 #define TCP_MAXSEG      0x02    /* set maximum segment size */
 159 #define TCP_NOPUSH      0x04    /* don't push last block of write */
 160 #define TCP_NOOPT       0x08    /* don't use TCP options */
 161 #define TCP_SIGNATURE_ENABLE    0x10    /* use MD5 digests (RFC2385) */
 162 #define TCP_KEEPINIT    0x20    /* set max time to establish connection */
 163 /* 0x40 unused */
 164 #define TCP_FASTKEEP    0x80
 165 #define TCP_KEEPIDLE    0x100   /* set time before keepalive probes begin */
 166 #define TCP_KEEPINTVL   0x200   /* set time between keepalive probes */
 167 #define TCP_KEEPCNT     0x400   /* set max number of keepalive probes */
 168 #endif /* __BSD_VISIBLE */
 169
 170 #endif