1/* $OpenBSD: tcp.h,v 1.24 2023/05/19 01:04:39 guenther 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#include <sys/cdefs.h>
39
40#if __BSD_VISIBLE
41
42typedef u_int32_t tcp_seq;
43
44/*
45 * TCP header.
46 * Per RFC 793, September, 1981.
47 */
48struct tcphdr {
49 u_int16_t th_sport; /* source port */
50 u_int16_t th_dport; /* destination port */
51 tcp_seq th_seq; /* sequence number */
52 tcp_seq th_ack; /* acknowledgement number */
53#if _BYTE_ORDER == _LITTLE_ENDIAN
54 u_int32_t th_x2:4, /* (unused) */
55 th_off:4; /* data offset */
56#endif
57#if _BYTE_ORDER == _BIG_ENDIAN
58 u_int32_t th_off:4, /* data offset */
59 th_x2:4; /* (unused) */
60#endif
61 u_int8_t th_flags;
62#define TH_FIN 0x01
63#define TH_SYN 0x02
64#define TH_RST 0x04
65#define TH_PUSH 0x08
66#define TH_ACK 0x10
67#define TH_URG 0x20
68#define TH_ECE 0x40
69#define TH_CWR 0x80
70 u_int16_t th_win; /* window */
71 u_int16_t th_sum; /* checksum */
72 u_int16_t th_urp; /* urgent pointer */
73};
74#define th_reseqlen th_urp /* TCP data length for
75 resequencing/reassembly */
76
77#define TCPOPT_EOL 0
78#define TCPOPT_NOP 1
79#define TCPOPT_MAXSEG 2
80#define TCPOLEN_MAXSEG 4
81#define TCPOPT_WINDOW 3
82#define TCPOLEN_WINDOW 3
83#define TCPOPT_SACK_PERMITTED 4 /* Experimental */
84#define TCPOLEN_SACK_PERMITTED 2
85#define TCPOPT_SACK 5 /* Experimental */
86#define TCPOLEN_SACK 8 /* 2*sizeof(tcp_seq) */
87#define TCPOPT_TIMESTAMP 8
88#define TCPOLEN_TIMESTAMP 10
89#define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */
90#define TCPOPT_SIGNATURE 19
91#define TCPOLEN_SIGNATURE 18
92#define TCPOLEN_SIGLEN (TCPOLEN_SIGNATURE+2) /* padding */
93
94#define MAX_TCPOPTLEN 40 /* Absolute maximum TCP options len */
95
96#define TCPOPT_TSTAMP_HDR \
97 (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP)
98
99/* Option definitions */
100#define TCPOPT_SACK_PERMIT_HDR \
101(TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_SACK_PERMITTED<<8|TCPOLEN_SACK_PERMITTED)
102#define TCPOPT_SACK_HDR (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_SACK<<8)
103/* Miscellaneous constants */
104#define MAX_SACK_BLKS 6 /* Max # SACK blocks stored at sender side */
105#define TCP_MAX_SACK 3 /* Max # SACKs sent in any segment */
106#define TCP_SACKHOLE_LIMIT 128 /* Max # SACK holes per connection */
107
108/*
109 * Default maximum segment size for TCP.
110 * With an IP MSS of 576, this is 536,
111 * but 512 is probably more convenient.
112 * This should be defined as min(512, IP_MSS - sizeof (struct tcpiphdr)).
113 */
114#define TCP_MSS 512
115
116#define TCP_MAXWIN 65535 /* largest value for (unscaled) window */
117
118#define TCP_MAX_WINSHIFT 14 /* maximum window shift */
119
120/*
121 * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits
122 * the caller to query certain information about the state of a TCP
123 * connection. Provide an overlapping set of fields with the Linux
124 * implementation, but at the same time add a lot of OpenBSD specific
125 * extra information.
126 */
127struct tcp_info {
128 uint8_t tcpi_state; /* TCP FSM state. */
129 uint8_t __tcpi_ca_state;
130 uint8_t __tcpi_retransmits;
131 uint8_t __tcpi_probes;
132 uint8_t __tcpi_backoff;
133 uint8_t tcpi_options; /* Options enabled on conn. */
134#define TCPI_OPT_TIMESTAMPS 0x01
135#define TCPI_OPT_SACK 0x02
136#define TCPI_OPT_WSCALE 0x04
137#define TCPI_OPT_ECN 0x08
138#define TCPI_OPT_TOE 0x10
139 uint8_t tcpi_snd_wscale; /* RFC1323 send shift value. */
140 uint8_t tcpi_rcv_wscale; /* RFC1323 recv shift value. */
141
142 uint32_t tcpi_rto; /* Retransmission timeout (usec). */
143 uint32_t __tcpi_ato;
144 uint32_t tcpi_snd_mss; /* Max segment size for send. */
145 uint32_t tcpi_rcv_mss; /* Max segment size for recv. */
146
147 uint32_t __tcpi_unacked;
148 uint32_t __tcpi_sacked;
149 uint32_t __tcpi_lost;
150 uint32_t __tcpi_retrans;
151 uint32_t __tcpi_fackets;
152
153 /* Times; measurements in usecs. */
154 uint32_t tcpi_last_data_sent; /* since last sent data. */
155 uint32_t tcpi_last_ack_sent; /* since last sent ack. */
156 uint32_t tcpi_last_data_recv; /* since last recv data. */
157 uint32_t tcpi_last_ack_recv; /* since last recv ack. */
158
159 /* Metrics; variable units. */
160 uint32_t __tcpi_pmtu;
161 uint32_t __tcpi_rcv_ssthresh;
162 uint32_t tcpi_rtt; /* Smoothed RTT in usecs. */
163 uint32_t tcpi_rttvar; /* RTT variance in usecs. */
164 uint32_t tcpi_snd_ssthresh; /* Slow start threshold. */
165 uint32_t tcpi_snd_cwnd; /* Send congestion window. */
166 uint32_t __tcpi_advmss;
167 uint32_t __tcpi_reordering;
168
169 uint32_t __tcpi_rcv_rtt;
170 uint32_t tcpi_rcv_space; /* Advertised recv window. */
171
172 /*
173 * Members below this point are only set if process is privileged,
174 * otherwise values will be 0.
175 */
176
177 /* FreeBSD/NetBSD extensions to tcp_info. */
178 uint32_t tcpi_snd_wnd; /* Advertised send window. */
179 uint32_t tcpi_snd_nxt; /* Next egress seqno */
180 uint32_t tcpi_rcv_nxt; /* Next ingress seqno */
181 uint32_t tcpi_toe_tid; /* HWTID for TOE endpoints */
182 uint32_t tcpi_snd_rexmitpack; /* Retransmitted packets */
183 uint32_t tcpi_rcv_ooopack; /* Out-of-order packets */
184 uint32_t tcpi_snd_zerowin; /* Zero-sized windows sent */
185
186 /* OpenBSD extensions */
187 uint32_t tcpi_rttmin;
188 uint32_t tcpi_max_sndwnd;
189 uint32_t tcpi_rcv_adv;
190 uint32_t tcpi_rcv_up;
191 uint32_t tcpi_snd_una;
192 uint32_t tcpi_snd_up;
193 uint32_t tcpi_snd_wl1;
194 uint32_t tcpi_snd_wl2;
195 uint32_t tcpi_snd_max;
196 uint32_t tcpi_ts_recent;
197 uint32_t tcpi_ts_recent_age;
198 uint32_t tcpi_rfbuf_cnt;
199 uint32_t tcpi_rfbuf_ts;
200 uint32_t tcpi_so_rcv_sb_cc;
201 uint32_t tcpi_so_rcv_sb_hiwat;
202 uint32_t tcpi_so_rcv_sb_lowat;
203 uint32_t tcpi_so_rcv_sb_wat;
204 uint32_t tcpi_so_snd_sb_cc;
205 uint32_t tcpi_so_snd_sb_hiwat;
206 uint32_t tcpi_so_snd_sb_lowat;
207 uint32_t tcpi_so_snd_sb_wat;
208};
209
210#endif /* __BSD_VISIBLE */
211
212/*
213 * User-settable options (used with setsockopt).
214 */
215#define TCP_NODELAY 0x01 /* don't delay send to coalesce pkts */
216#define TCP_MAXSEG 0x02 /* set maximum segment size */
217#define TCP_MD5SIG 0x04 /* enable TCP MD5 signature option */
218#define TCP_SACK_ENABLE 0x08 /* enable SACKs (if disabled by def.) */
219#define TCP_INFO 0x09 /* retrieve tcp_info structure */
220#define TCP_NOPUSH 0x10 /* don't push last block of write */
221
222#endif /* _NETINET_TCP_H_ */