xref: /freebsd/sys/netinet/tcp.h (revision 0c43d89a0d8e976ca494d4837f4c1f3734d2c300)
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  * $Id: tcp.h,v 1.2 1994/08/02 07:48:52 davidg Exp $
35  */
36 
37 #ifndef _NETINET_TCP_H_
38 #define _NETINET_TCP_H_
39 
40 typedef	u_long	tcp_seq;
41 /*
42  * TCP header.
43  * Per RFC 793, September, 1981.
44  */
45 struct tcphdr {
46 	u_short	th_sport;		/* source port */
47 	u_short	th_dport;		/* destination port */
48 	tcp_seq	th_seq;			/* sequence number */
49 	tcp_seq	th_ack;			/* acknowledgement number */
50 #if BYTE_ORDER == LITTLE_ENDIAN
51 	u_char	th_x2:4,		/* (unused) */
52 		th_off:4;		/* data offset */
53 #endif
54 #if BYTE_ORDER == BIG_ENDIAN
55 	u_char	th_off:4,		/* data offset */
56 		th_x2:4;		/* (unused) */
57 #endif
58 	u_char	th_flags;
59 #define	TH_FIN	0x01
60 #define	TH_SYN	0x02
61 #define	TH_RST	0x04
62 #define	TH_PUSH	0x08
63 #define	TH_ACK	0x10
64 #define	TH_URG	0x20
65 	u_short	th_win;			/* window */
66 	u_short	th_sum;			/* checksum */
67 	u_short	th_urp;			/* urgent pointer */
68 };
69 
70 #define	TCPOPT_EOL		0
71 #define	TCPOPT_NOP		1
72 #define	TCPOPT_MAXSEG		2
73 #define    TCPOLEN_MAXSEG		4
74 #define TCPOPT_WINDOW		3
75 #define    TCPOLEN_WINDOW		3
76 #define TCPOPT_SACK_PERMITTED	4		/* Experimental */
77 #define    TCPOLEN_SACK_PERMITTED	2
78 #define TCPOPT_SACK		5		/* Experimental */
79 #define TCPOPT_TIMESTAMP	8
80 #define    TCPOLEN_TIMESTAMP		10
81 #define    TCPOLEN_TSTAMP_APPA		(TCPOLEN_TIMESTAMP+2) /* appendix A */
82 
83 #define TCPOPT_TSTAMP_HDR	\
84     (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP)
85 
86 /*
87  * Default maximum segment size for TCP.
88  * With an IP MSS of 576, this is 536,
89  * but 512 is probably more convenient.
90  * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
91  */
92 #define	TCP_MSS	512
93 
94 #define	TCP_MAXWIN	65535	/* largest value for (unscaled) window */
95 
96 #define TCP_MAX_WINSHIFT	14	/* maximum window shift */
97 
98 /*
99  * User-settable options (used with setsockopt).
100  */
101 #define	TCP_NODELAY	0x01	/* don't delay send to coalesce packets */
102 #define	TCP_MAXSEG	0x02	/* set maximum segment size */
103 
104 #endif
105