FreeBSD/Linux Kernel Cross Reference
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: releng/5.2/sys/netinet/tcp.h 124291 2004-01-09 14:29:52Z andre $
35 */
36
37 #ifndef _NETINET_TCP_H_
38 #define _NETINET_TCP_H_
39
40 #include <sys/cdefs.h>
41
42 #if __BSD_VISIBLE
43
44 typedef u_int32_t tcp_seq;
45 typedef u_int32_t tcp_cc; /* connection count per rfc1644 */
46
47 #define tcp6_seq tcp_seq /* for KAME src sync over BSD*'s */
48 #define tcp6hdr tcphdr /* for KAME src sync over BSD*'s */
49
50 /*
51 * TCP header.
52 * Per RFC 793, September, 1981.
53 */
54 struct tcphdr {
55 u_short th_sport; /* source port */
56 u_short th_dport; /* destination port */
57 tcp_seq th_seq; /* sequence number */
58 tcp_seq th_ack; /* acknowledgement number */
59 #if BYTE_ORDER == LITTLE_ENDIAN
60 u_int th_x2:4, /* (unused) */
61 th_off:4; /* data offset */
62 #endif
63 #if BYTE_ORDER == BIG_ENDIAN
64 u_int th_off:4, /* data offset */
65 th_x2:4; /* (unused) */
66 #endif
67 u_char th_flags;
68 #define TH_FIN 0x01
69 #define TH_SYN 0x02
70 #define TH_RST 0x04
71 #define TH_PUSH 0x08
72 #define TH_ACK 0x10
73 #define TH_URG 0x20
74 #define TH_ECE 0x40
75 #define TH_CWR 0x80
76 #define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG|TH_ECE|TH_CWR)
77
78 u_short th_win; /* window */
79 u_short th_sum; /* checksum */
80 u_short th_urp; /* urgent pointer */
81 };
82
83 #define TCPOPT_EOL 0
84 #define TCPOPT_NOP 1
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 /* Experimental */
90 #define TCPOLEN_SACK_PERMITTED 2
91 #define TCPOPT_SACK 5 /* Experimental */
92 #define TCPOPT_TIMESTAMP 8
93 #define TCPOLEN_TIMESTAMP 10
94 #define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */
95 #define TCPOPT_TSTAMP_HDR \
96 (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP)
97
98 #define TCPOPT_CC 11 /* CC options: RFC-1644 */
99 #define TCPOPT_CCNEW 12
100 #define TCPOPT_CCECHO 13
101 #define TCPOLEN_CC 6
102 #define TCPOLEN_CC_APPA (TCPOLEN_CC+2)
103 #define TCPOPT_CC_HDR(ccopt) \
104 (TCPOPT_NOP<<24|TCPOPT_NOP<<16|(ccopt)<<8|TCPOLEN_CC)
105
106 /*
107 * Default maximum segment size for TCP.
108 * With an IP MTU of 576, this is 536,
109 * but 512 is probably more convenient.
110 * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
111 */
112 #define TCP_MSS 512
113 /*
114 * TCP_MINMSS is defined to be 216 which is fine for the smallest
115 * link MTU (256 bytes, AX.25 packet radio) in the Internet.
116 * However it is very unlikely to come across such low MTU interfaces
117 * these days (anno dato 2003).
118 * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments.
119 * Setting this to "" disables the minmss check.
120 */
121 #define TCP_MINMSS 216
122 /*
123 * TCP_MINMSSOVERLOAD is defined to be 1000 which should cover any type
124 * of interactive TCP session.
125 * See tcp_subr.c tcp_minmssoverload SYSCTL declaration and tcp_input.c
126 * for more comments.
127 * Setting this to "" disables the minmssoverload check.
128 */
129 #define TCP_MINMSSOVERLOAD 0
130
131 /*
132 * Default maximum segment size for TCP6.
133 * With an IP6 MSS of 1280, this is 1220,
134 * but 1024 is probably more convenient. (xxx kazu in doubt)
135 * This should be defined as MIN(1024, IP6_MSS - sizeof (struct tcpip6hdr))
136 */
137 #define TCP6_MSS 1024
138
139 #define TCP_MAXWIN 65535 /* largest value for (unscaled) window */
140 #define TTCP_CLIENT_SND_WND 4096 /* dflt send window for T/TCP client */
141
142 #define TCP_MAX_WINSHIFT 14 /* maximum window shift */
143
144 #define TCP_MAXBURST 4 /* maximum segments in a burst */
145
146 #define TCP_MAXHLEN (0xf<<2) /* max length of header in bytes */
147 #define TCP_MAXOLEN (TCP_MAXHLEN - sizeof(struct tcphdr))
148 /* max space left for options */
149 #endif /* __BSD_VISIBLE */
150
151 /*
152 * User-settable options (used with setsockopt).
153 */
154 #define TCP_NODELAY 0x01 /* don't delay send to coalesce packets */
155 #if __BSD_VISIBLE
156 #define TCP_MAXSEG 0x02 /* set maximum segment size */
157 #define TCP_NOPUSH 0x04 /* don't push last block of write */
158 #define TCP_NOOPT 0x08 /* don't use TCP options */
159 #endif
160
161 #endif /* !_NETINET_TCP_H_ */
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