tcp.h revision 133874
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 * 4. 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: head/sys/netinet/tcp.h 133874 2004-08-16 18:32:07Z rwatson $ 31 */ 32 33#ifndef _NETINET_TCP_H_ 34#define _NETINET_TCP_H_ 35 36#include <sys/cdefs.h> 37 38#if __BSD_VISIBLE 39 40typedef u_int32_t tcp_seq; 41typedef u_int32_t tcp_cc; /* connection count per rfc1644 */ 42 43#define tcp6_seq tcp_seq /* for KAME src sync over BSD*'s */ 44#define tcp6hdr tcphdr /* for KAME src sync over BSD*'s */ 45 46/* 47 * TCP header. 48 * Per RFC 793, September, 1981. 49 */ 50struct tcphdr { 51 u_short th_sport; /* source port */ 52 u_short th_dport; /* destination port */ 53 tcp_seq th_seq; /* sequence number */ 54 tcp_seq th_ack; /* acknowledgement number */ 55#if BYTE_ORDER == LITTLE_ENDIAN 56 u_int th_x2:4, /* (unused) */ 57 th_off:4; /* data offset */ 58#endif 59#if BYTE_ORDER == BIG_ENDIAN 60 u_int th_off:4, /* data offset */ 61 th_x2:4; /* (unused) */ 62#endif 63 u_char th_flags; 64#define TH_FIN 0x01 65#define TH_SYN 0x02 66#define TH_RST 0x04 67#define TH_PUSH 0x08 68#define TH_ACK 0x10 69#define TH_URG 0x20 70#define TH_ECE 0x40 71#define TH_CWR 0x80 72#define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG|TH_ECE|TH_CWR) 73 74 u_short th_win; /* window */ 75 u_short th_sum; /* checksum */ 76 u_short th_urp; /* urgent pointer */ 77}; 78 79#define TCPOPT_EOL 0 80#define TCPOPT_NOP 1 81#define TCPOPT_MAXSEG 2 82#define TCPOLEN_MAXSEG 4 83#define TCPOPT_WINDOW 3 84#define TCPOLEN_WINDOW 3 85#define TCPOPT_SACK_PERMITTED 4 /* Experimental */ 86#define TCPOLEN_SACK_PERMITTED 2 87#define TCPOPT_SACK 5 /* Experimental */ 88#define TCPOLEN_SACK 8 /* 2*sizeof(tcp_seq) */ 89#define TCPOPT_TIMESTAMP 8 90#define TCPOLEN_TIMESTAMP 10 91#define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */ 92#define TCPOPT_TSTAMP_HDR \ 93 (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP) 94 95#define MAX_TCPOPTLEN 40 /* Absolute maximum TCP options len */ 96 97#define TCPOPT_CC 11 /* CC options: RFC-1644 */ 98#define TCPOPT_CCNEW 12 99#define TCPOPT_CCECHO 13 100#define TCPOLEN_CC 6 101#define TCPOLEN_CC_APPA (TCPOLEN_CC+2) 102#define TCPOPT_CC_HDR(ccopt) \ 103 (TCPOPT_NOP<<24|TCPOPT_NOP<<16|(ccopt)<<8|TCPOLEN_CC) 104#define TCPOPT_SIGNATURE 19 /* Keyed MD5: RFC 2385 */ 105#define TCPOLEN_SIGNATURE 18 106 107/* Option definitions */ 108#define TCPOPT_SACK_PERMIT_HDR \ 109(TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_SACK_PERMITTED<<8|TCPOLEN_SACK_PERMITTED) 110#define TCPOPT_SACK_HDR (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_SACK<<8) 111/* Miscellaneous constants */ 112#define MAX_SACK_BLKS 6 /* Max # SACK blocks stored at sender side */ 113#define TCP_MAX_SACK 3 /* MAX # SACKs sent in any segment */ 114 115 116/* 117 * Default maximum segment size for TCP. 118 * With an IP MTU of 576, this is 536, 119 * but 512 is probably more convenient. 120 * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)). 121 */ 122#define TCP_MSS 512 123/* 124 * TCP_MINMSS is defined to be 216 which is fine for the smallest 125 * link MTU (256 bytes, AX.25 packet radio) in the Internet. 126 * However it is very unlikely to come across such low MTU interfaces 127 * these days (anno dato 2003). 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 216 132/* 133 * TCP_MINMSSOVERLOAD is defined to be 1000 which should cover any type 134 * of interactive TCP session. 135 * See tcp_subr.c tcp_minmssoverload SYSCTL declaration and tcp_input.c 136 * for more comments. 137 * Setting this to "0" disables the minmssoverload check. 138 */ 139#define TCP_MINMSSOVERLOAD 0 /* XXX: Disabled until refined */ 140 141/* 142 * Default maximum segment size for TCP6. 143 * With an IP6 MSS of 1280, this is 1220, 144 * but 1024 is probably more convenient. (xxx kazu in doubt) 145 * This should be defined as MIN(1024, IP6_MSS - sizeof (struct tcpip6hdr)) 146 */ 147#define TCP6_MSS 1024 148 149#define TCP_MAXWIN 65535 /* largest value for (unscaled) window */ 150#define TTCP_CLIENT_SND_WND 4096 /* dflt send window for T/TCP client */ 151 152#define TCP_MAX_WINSHIFT 14 /* maximum window shift */ 153 154#define TCP_MAXBURST 4 /* maximum segments in a burst */ 155 156#define TCP_MAXHLEN (0xf<<2) /* max length of header in bytes */ 157#define TCP_MAXOLEN (TCP_MAXHLEN - sizeof(struct tcphdr)) 158 /* max space left for options */ 159#endif /* __BSD_VISIBLE */ 160 161/* 162 * User-settable options (used with setsockopt). 163 */ 164#define TCP_NODELAY 0x01 /* don't delay send to coalesce packets */ 165#if __BSD_VISIBLE 166#define TCP_MAXSEG 0x02 /* set maximum segment size */ 167#define TCP_NOPUSH 0x04 /* don't push last block of write */ 168#define TCP_NOOPT 0x08 /* don't use TCP options */ 169#define TCP_MD5SIG 0x10 /* use MD5 digests (RFC2385) */ 170#endif 171 172#endif /* !_NETINET_TCP_H_ */ 173