1 /* $OpenBSD: tcp.h,v 1.17 2006/04/27 02:19:32 tedu Exp $ */
2 /* $NetBSD: tcp.h,v 1.8 1995/04/17 05:32:58 cgd Exp $ */
3
4 /*
5 * Copyright (c) 1982, 1986, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * @(#)tcp.h 8.1 (Berkeley) 6/10/93
33 */
34
35 #ifndef _NETINET_TCP_H_
36 #define _NETINET_TCP_H_
37
38 typedef u_int32_t tcp_seq;
39
40 /*
41 * TCP header.
42 * Per RFC 793, September, 1981.
43 */
44 struct tcphdr {
45 u_int16_t th_sport; /* source port */
46 u_int16_t th_dport; /* destination port */
47 tcp_seq th_seq; /* sequence number */
48 tcp_seq th_ack; /* acknowledgement number */
49 #if _BYTE_ORDER == _LITTLE_ENDIAN
50 u_int th_x2:4, /* (unused) */
51 th_off:4; /* data offset */
52 #endif
53 #if _BYTE_ORDER == _BIG_ENDIAN
54 u_int th_off:4, /* data offset */
55 th_x2:4; /* (unused) */
56 #endif
57 u_int8_t th_flags;
58 #define TH_FIN 0x01
59 #define TH_SYN 0x02
60 #define TH_RST 0x04
61 #define TH_PUSH 0x08
62 #define TH_ACK 0x10
63 #define TH_URG 0x20
64 #define TH_ECE 0x40
65 #define TH_CWR 0x80
66 u_int16_t th_win; /* window */
67 u_int16_t th_sum; /* checksum */
68 u_int16_t th_urp; /* urgent pointer */
69 };
70 #define th_reseqlen th_urp /* TCP data length for
71 resequencing/reassembly */
72
73 #define TCPOPT_EOL 0
74 #define TCPOPT_NOP 1
75 #define TCPOPT_MAXSEG 2
76 #define TCPOLEN_MAXSEG 4
77 #define TCPOPT_WINDOW 3
78 #define TCPOLEN_WINDOW 3
79 #define TCPOPT_SACK_PERMITTED 4 /* Experimental */
80 #define TCPOLEN_SACK_PERMITTED 2
81 #define TCPOPT_SACK 5 /* Experimental */
82 #define TCPOLEN_SACK 8 /* 2*sizeof(tcp_seq) */
83 #define TCPOPT_TIMESTAMP 8
84 #define TCPOLEN_TIMESTAMP 10
85 #define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */
86 #define TCPOPT_SIGNATURE 19
87 #define TCPOLEN_SIGNATURE 18
88 #define TCPOLEN_SIGLEN (TCPOLEN_SIGNATURE+2) /* padding */
89
90 #define MAX_TCPOPTLEN 40 /* Absolute maximum TCP options len */
91
92 #define TCPOPT_TSTAMP_HDR \
93 (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP)
94
95 /* Option definitions */
96 #define TCPOPT_SACK_PERMIT_HDR \
97 (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_SACK_PERMITTED<<8|TCPOLEN_SACK_PERMITTED)
98 #define TCPOPT_SACK_HDR (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_SACK<<8)
99 /* Miscellaneous constants */
100 #define MAX_SACK_BLKS 6 /* Max # SACK blocks stored at sender side */
101 #define TCP_MAX_SACK 3 /* MAX # SACKs sent in any segment */
102
103 #define TCP_MAXBURST 4 /* Max # packets after leaving Fast Rxmit */
104
105 /*
106 * Default maximum segment size for TCP.
107 * With an IP MSS of 576, this is 536,
108 * but 512 is probably more convenient.
109 * This should be defined as min(512, IP_MSS - sizeof (struct tcpiphdr)).
110 */
111 #define TCP_MSS 512
112
113 #define TCP_MAXWIN 65535 /* largest value for (unscaled) window */
114
115 #define TCP_MAX_WINSHIFT 14 /* maximum window shift */
116
117 /*
118 * User-settable options (used with setsockopt).
119 */
120 #define TCP_NODELAY 0x01 /* don't delay send to coalesce pkts */
121 #define TCP_MAXSEG 0x02 /* set maximum segment size */
122 #define TCP_MD5SIG 0x04 /* enable TCP MD5 signature option */
123 #define TCP_SACK_ENABLE 0x08 /* enable SACKs (if disabled by def.) */
124
125 #endif /* _NETINET_TCP_H_ */