summaryrefslogtreecommitdiffstats
path: root/sys/netinet/tcp.h
blob: 805a5616dc1cbc3c780e96ca091ee742ac796e52 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
/*-
 * Copyright (c) 1982, 1986, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)tcp.h	8.1 (Berkeley) 6/10/93
 * $FreeBSD$
 */

#ifndef _NETINET_TCP_H_
#define _NETINET_TCP_H_

#include <sys/cdefs.h>
#include <sys/types.h>

#if __BSD_VISIBLE

typedef	u_int32_t tcp_seq;

#define tcp6_seq	tcp_seq	/* for KAME src sync over BSD*'s */
#define tcp6hdr		tcphdr	/* for KAME src sync over BSD*'s */

/*
 * TCP header.
 * Per RFC 793, September, 1981.
 */
struct tcphdr {
	u_short	th_sport;		/* source port */
	u_short	th_dport;		/* destination port */
	tcp_seq	th_seq;			/* sequence number */
	tcp_seq	th_ack;			/* acknowledgement number */
#if BYTE_ORDER == LITTLE_ENDIAN
	u_char	th_x2:4,		/* (unused) */
		th_off:4;		/* data offset */
#endif
#if BYTE_ORDER == BIG_ENDIAN
	u_char	th_off:4,		/* data offset */
		th_x2:4;		/* (unused) */
#endif
	u_char	th_flags;
#define	TH_FIN	0x01
#define	TH_SYN	0x02
#define	TH_RST	0x04
#define	TH_PUSH	0x08
#define	TH_ACK	0x10
#define	TH_URG	0x20
#define	TH_ECE	0x40
#define	TH_CWR	0x80
#define	TH_FLAGS	(TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG|TH_ECE|TH_CWR)
#define	PRINT_TH_FLAGS	"\20\1FIN\2SYN\3RST\4PUSH\5ACK\6URG\7ECE\10CWR"

	u_short	th_win;			/* window */
	u_short	th_sum;			/* checksum */
	u_short	th_urp;			/* urgent pointer */
};

#define	TCPOPT_EOL		0
#define	   TCPOLEN_EOL			1
#define	TCPOPT_PAD		0		/* padding after EOL */
#define	   TCPOLEN_PAD			1
#define	TCPOPT_NOP		1
#define	   TCPOLEN_NOP			1
#define	TCPOPT_MAXSEG		2
#define    TCPOLEN_MAXSEG		4
#define TCPOPT_WINDOW		3
#define    TCPOLEN_WINDOW		3
#define TCPOPT_SACK_PERMITTED	4
#define    TCPOLEN_SACK_PERMITTED	2
#define TCPOPT_SACK		5
#define	   TCPOLEN_SACKHDR		2
#define    TCPOLEN_SACK			8	/* 2*sizeof(tcp_seq) */
#define TCPOPT_TIMESTAMP	8
#define    TCPOLEN_TIMESTAMP		10
#define    TCPOLEN_TSTAMP_APPA		(TCPOLEN_TIMESTAMP+2) /* appendix A */
#define	TCPOPT_SIGNATURE	19		/* Keyed MD5: RFC 2385 */
#define	   TCPOLEN_SIGNATURE		18

/* Miscellaneous constants */
#define	MAX_SACK_BLKS	6	/* Max # SACK blocks stored at receiver side */
#define	TCP_MAX_SACK	4	/* MAX # SACKs sent in any segment */


/*
 * The default maximum segment size (MSS) to be used for new TCP connections
 * when path MTU discovery is not enabled.
 *
 * RFC879 derives the default MSS from the largest datagram size hosts are
 * minimally required to handle directly or through IP reassembly minus the
 * size of the IP and TCP header.  With IPv6 the minimum MTU is specified
 * in RFC2460.
 *
 * For IPv4 the MSS is 576 - sizeof(struct tcpiphdr)
 * For IPv6 the MSS is IPV6_MMTU - sizeof(struct ip6_hdr) - sizeof(struct tcphdr)
 *
 * We use explicit numerical definition here to avoid header pollution.
 */
#define	TCP_MSS		536
#define	TCP6_MSS	1220

/*
 * Limit the lowest MSS we accept for path MTU discovery and the TCP SYN MSS
 * option.  Allowing low values of MSS can consume significant resources and
 * be used to mount a resource exhaustion attack.
 * Connections requesting lower MSS values will be rounded up to this value
 * and the IP_DF flag will be cleared to allow fragmentation along the path.
 *
 * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments.  Setting
 * it to "0" disables the minmss check.
 *
 * The default value is fine for TCP across the Internet's smallest official
 * link MTU (256 bytes for AX.25 packet radio).  However, a connection is very
 * unlikely to come across such low MTU interfaces these days (anno domini 2003).
 */
#define	TCP_MINMSS 216

#define	TCP_MAXWIN	65535	/* largest value for (unscaled) window */
#define	TTCP_CLIENT_SND_WND	4096	/* dflt send window for T/TCP client */

#define TCP_MAX_WINSHIFT	14	/* maximum window shift */

#define TCP_MAXBURST		4	/* maximum segments in a burst */

#define TCP_MAXHLEN	(0xf<<2)	/* max length of header in bytes */
#define TCP_MAXOLEN	(TCP_MAXHLEN - sizeof(struct tcphdr))
					/* max space left for options */
#endif /* __BSD_VISIBLE */

/*
 * User-settable options (used with setsockopt).
 */
#define	TCP_NODELAY	0x01	/* don't delay send to coalesce packets */
#if __BSD_VISIBLE
#define	TCP_MAXSEG	0x02	/* set maximum segment size */
#define TCP_NOPUSH	0x04	/* don't push last block of write */
#define TCP_NOOPT	0x08	/* don't use TCP options */
#define TCP_MD5SIG	0x10	/* use MD5 digests (RFC2385) */
#define	TCP_INFO	0x20	/* retrieve tcp_info structure */
#define	TCP_CONGESTION	0x40	/* get/set congestion control algorithm */

#define	TCP_CA_NAME_MAX	16	/* max congestion control name length */

#define	TCPI_OPT_TIMESTAMPS	0x01
#define	TCPI_OPT_SACK		0x02
#define	TCPI_OPT_WSCALE		0x04
#define	TCPI_OPT_ECN		0x08
#define	TCPI_OPT_TOE		0x10

/*
 * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits
 * the caller to query certain information about the state of a TCP
 * connection.  We provide an overlapping set of fields with the Linux
 * implementation, but since this is a fixed size structure, room has been
 * left for growth.  In order to maximize potential future compatibility with
 * the Linux API, the same variable names and order have been adopted, and
 * padding left to make room for omitted fields in case they are added later.
 *
 * XXX: This is currently an unstable ABI/API, in that it is expected to
 * change.
 */
struct tcp_info {
	u_int8_t	tcpi_state;		/* TCP FSM state. */
	u_int8_t	__tcpi_ca_state;
	u_int8_t	__tcpi_retransmits;
	u_int8_t	__tcpi_probes;
	u_int8_t	__tcpi_backoff;
	u_int8_t	tcpi_options;		/* Options enabled on conn. */
	u_int8_t	tcpi_snd_wscale:4,	/* RFC1323 send shift value. */
			tcpi_rcv_wscale:4;	/* RFC1323 recv shift value. */

	u_int32_t	tcpi_rto;		/* Retransmission timeout (usec). */
	u_int32_t	__tcpi_ato;
	u_int32_t	tcpi_snd_mss;		/* Max segment size for send. */
	u_int32_t	tcpi_rcv_mss;		/* Max segment size for receive. */

	u_int32_t	__tcpi_unacked;
	u_int32_t	__tcpi_sacked;
	u_int32_t	__tcpi_lost;
	u_int32_t	__tcpi_retrans;
	u_int32_t	__tcpi_fackets;

	/* Times; measurements in usecs. */
	u_int32_t	__tcpi_last_data_sent;
	u_int32_t	__tcpi_last_ack_sent;	/* Also unimpl. on Linux? */
	u_int32_t	tcpi_last_data_recv;	/* Time since last recv data. */
	u_int32_t	__tcpi_last_ack_recv;

	/* Metrics; variable units. */
	u_int32_t	__tcpi_pmtu;
	u_int32_t	__tcpi_rcv_ssthresh;
	u_int32_t	tcpi_rtt;		/* Smoothed RTT in usecs. */
	u_int32_t	tcpi_rttvar;		/* RTT variance in usecs. */
	u_int32_t	tcpi_snd_ssthresh;	/* Slow start threshold. */
	u_int32_t	tcpi_snd_cwnd;		/* Send congestion window. */
	u_int32_t	__tcpi_advmss;
	u_int32_t	__tcpi_reordering;

	u_int32_t	__tcpi_rcv_rtt;
	u_int32_t	tcpi_rcv_space;		/* Advertised recv window. */

	/* FreeBSD extensions to tcp_info. */
	u_int32_t	tcpi_snd_wnd;		/* Advertised send window. */
	u_int32_t	tcpi_snd_bwnd;		/* No longer used. */
	u_int32_t	tcpi_snd_nxt;		/* Next egress seqno */
	u_int32_t	tcpi_rcv_nxt;		/* Next ingress seqno */
	u_int32_t	tcpi_toe_tid;		/* HWTID for TOE endpoints */
	u_int32_t	tcpi_snd_rexmitpack;	/* Retransmitted packets */
	u_int32_t	tcpi_rcv_ooopack;	/* Out-of-order packets */
	u_int32_t	tcpi_snd_zerowin;	/* Zero-sized windows sent */
	
	/* Padding to grow without breaking ABI. */
	u_int32_t	__tcpi_pad[26];		/* Padding. */
};
#endif

#endif /* !_NETINET_TCP_H_ */
OpenPOWER on IntegriCloud