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 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)tcp.h 8.1 (Berkeley) 6/10/93
30 * $FreeBSD: releng/8.4/sys/netinet/tcp.h 247526 2013-03-01 03:05:08Z jhb $
31 */
32
33 #ifndef _NETINET_TCP_H_
34 #define _NETINET_TCP_H_
35
36 #include <sys/cdefs.h>
37
38 #if __BSD_VISIBLE
39
40 typedef u_int32_t tcp_seq;
41
42 #define tcp6_seq tcp_seq /* for KAME src sync over BSD*'s */
43 #define tcp6hdr tcphdr /* for KAME src sync over BSD*'s */
44
45 /*
46 * TCP header.
47 * Per RFC 793, September, 1981.
48 */
49 struct tcphdr {
50 u_short th_sport; /* source port */
51 u_short th_dport; /* destination port */
52 tcp_seq th_seq; /* sequence number */
53 tcp_seq th_ack; /* acknowledgement number */
54 #if BYTE_ORDER == LITTLE_ENDIAN
55 u_int th_x2:4, /* (unused) */
56 th_off:4; /* data offset */
57 #endif
58 #if BYTE_ORDER == BIG_ENDIAN
59 u_int th_off:4, /* data offset */
60 th_x2:4; /* (unused) */
61 #endif
62 u_char th_flags;
63 #define TH_FIN 0x01
64 #define TH_SYN 0x02
65 #define TH_RST 0x04
66 #define TH_PUSH 0x08
67 #define TH_ACK 0x10
68 #define TH_URG 0x20
69 #define TH_ECE 0x40
70 #define TH_CWR 0x80
71 #define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG|TH_ECE|TH_CWR)
72 #define PRINT_TH_FLAGS "\2\1FIN\2SYN\3RST\4PUSH\5ACK\6URG\7ECE\10CWR"
73
74 u_short th_win; /* window */
75 u_short th_sum; /* checksum */
76 u_short th_urp; /* urgent pointer */
77 };
78
79 #define TCPOPT_EOL 0
80 #define TCPOLEN_EOL 1
81 #define TCPOPT_PAD 0 /* padding after EOL */
82 #define TCPOLEN_PAD 1
83 #define TCPOPT_NOP 1
84 #define TCPOLEN_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
90 #define TCPOLEN_SACK_PERMITTED 2
91 #define TCPOPT_SACK 5
92 #define TCPOLEN_SACKHDR 2
93 #define TCPOLEN_SACK 8 /* 2*sizeof(tcp_seq) */
94 #define TCPOPT_TIMESTAMP 8
95 #define TCPOLEN_TIMESTAMP 10
96 #define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */
97 #define TCPOPT_SIGNATURE 19 /* Keyed MD5: RFC 2385 */
98 #define TCPOLEN_SIGNATURE 18
99
100 /* Miscellaneous constants */
101 #define MAX_SACK_BLKS 6 /* Max # SACK blocks stored at receiver side */
102 #define TCP_MAX_SACK 4 /* MAX # SACKs sent in any segment */
103
104
105 /*
106 * Default maximum segment size for TCP.
107 * With an IP MTU 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 * TCP_MINMSS is defined to be 216 which is fine for the smallest
114 * link MTU (256 bytes, AX.25 packet radio) in the Internet.
115 * However it is very unlikely to come across such low MTU interfaces
116 * these days (anno dato 2003).
117 * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments.
118 * Setting this to "" disables the minmss check.
119 */
120 #define TCP_MINMSS 216
121
122 /*
123 * Default maximum segment size for TCP6.
124 * With an IP6 MSS of 1280, this is 1220,
125 * but 1024 is probably more convenient. (xxx kazu in doubt)
126 * This should be defined as MIN(1024, IP6_MSS - sizeof (struct tcpip6hdr))
127 */
128 #define TCP6_MSS 1024
129
130 #define TCP_MAXWIN 65535 /* largest value for (unscaled) window */
131 #define TTCP_CLIENT_SND_WND 4096 /* dflt send window for T/TCP client */
132
133 #define TCP_MAX_WINSHIFT 14 /* maximum window shift */
134
135 #define TCP_MAXBURST 4 /* maximum segments in a burst */
136
137 #define TCP_MAXHLEN (0xf<<2) /* max length of header in bytes */
138 #define TCP_MAXOLEN (TCP_MAXHLEN - sizeof(struct tcphdr))
139 /* max space left for options */
140 #endif /* __BSD_VISIBLE */
141
142 /*
143 * User-settable options (used with setsockopt). These are discrete
144 * values and are not masked together. Some values appear to be
145 * bitmasks for historical reasons.
146 */
147 #define TCP_NODELAY 1 /* don't delay send to coalesce packets */
148 #if __BSD_VISIBLE
149 #define TCP_MAXSEG 2 /* set maximum segment size */
150 #define TCP_NOPUSH 4 /* don't push last block of write */
151 #define TCP_NOOPT 8 /* don't use TCP options */
152 #define TCP_MD5SIG 16 /* use MD5 digests (RFC2385) */
153 #define TCP_INFO 32 /* retrieve tcp_info structure */
154 #define TCP_CONGESTION 64 /* get/set congestion control algorithm */
155
156 /* Start of reserved space for third-party user-settable options. */
157 #define TCP_VENDOR SO_VENDOR
158
159 #define TCP_CA_NAME_MAX 16 /* max congestion control name length */
160
161 #define TCPI_OPT_TIMESTAMPS 0x01
162 #define TCPI_OPT_SACK 0x02
163 #define TCPI_OPT_WSCALE 0x04
164 #define TCPI_OPT_ECN 0x08
165 #define TCPI_OPT_TOE 0x10
166
167 /*
168 * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits
169 * the caller to query certain information about the state of a TCP
170 * connection. We provide an overlapping set of fields with the Linux
171 * implementation, but since this is a fixed size structure, room has been
172 * left for growth. In order to maximize potential future compatibility with
173 * the Linux API, the same variable names and order have been adopted, and
174 * padding left to make room for omitted fields in case they are added later.
175 *
176 * XXX: This is currently an unstable ABI/API, in that it is expected to
177 * change.
178 */
179 struct tcp_info {
180 u_int8_t tcpi_state; /* TCP FSM state. */
181 u_int8_t __tcpi_ca_state;
182 u_int8_t __tcpi_retransmits;
183 u_int8_t __tcpi_probes;
184 u_int8_t __tcpi_backoff;
185 u_int8_t tcpi_options; /* Options enabled on conn. */
186 u_int8_t tcpi_snd_wscale:4, /* RFC1323 send shift value. */
187 tcpi_rcv_wscale:4; /* RFC1323 recv shift value. */
188
189 u_int32_t tcpi_rto; /* Retransmission timeout (usec). */
190 u_int32_t __tcpi_ato;
191 u_int32_t tcpi_snd_mss; /* Max segment size for send. */
192 u_int32_t tcpi_rcv_mss; /* Max segment size for receive. */
193
194 u_int32_t __tcpi_unacked;
195 u_int32_t __tcpi_sacked;
196 u_int32_t __tcpi_lost;
197 u_int32_t __tcpi_retrans;
198 u_int32_t __tcpi_fackets;
199
200 /* Times; measurements in usecs. */
201 u_int32_t __tcpi_last_data_sent;
202 u_int32_t __tcpi_last_ack_sent; /* Also unimpl. on Linux? */
203 u_int32_t tcpi_last_data_recv; /* Time since last recv data. */
204 u_int32_t __tcpi_last_ack_recv;
205
206 /* Metrics; variable units. */
207 u_int32_t __tcpi_pmtu;
208 u_int32_t __tcpi_rcv_ssthresh;
209 u_int32_t tcpi_rtt; /* Smoothed RTT in usecs. */
210 u_int32_t tcpi_rttvar; /* RTT variance in usecs. */
211 u_int32_t tcpi_snd_ssthresh; /* Slow start threshold. */
212 u_int32_t tcpi_snd_cwnd; /* Send congestion window. */
213 u_int32_t __tcpi_advmss;
214 u_int32_t __tcpi_reordering;
215
216 u_int32_t __tcpi_rcv_rtt;
217 u_int32_t tcpi_rcv_space; /* Advertised recv window. */
218
219 /* FreeBSD extensions to tcp_info. */
220 u_int32_t tcpi_snd_wnd; /* Advertised send window. */
221 u_int32_t tcpi_snd_bwnd; /* Bandwidth send window. */
222 u_int32_t tcpi_snd_nxt; /* Next egress seqno */
223 u_int32_t tcpi_rcv_nxt; /* Next ingress seqno */
224 u_int32_t tcpi_toe_tid; /* HWTID for TOE endpoints */
225 u_int32_t tcpi_snd_rexmitpack; /* Retransmitted packets */
226 u_int32_t tcpi_rcv_ooopack; /* Out-of-order packets */
227 u_int32_t tcpi_snd_zerowin; /* Zero-sized windows sent */
228
229 /* Padding to grow without breaking ABI. */
230 u_int32_t __tcpi_pad[26]; /* Padding. */
231 };
232 #endif
233
234 #endif /* !_NETINET_TCP_H_ */
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