2 * Copyright (c) 1982, 1986, 1993
3 * The Regents of the University of California. All rights reserved.
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6 * modification, are permitted provided that the following conditions
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29 * @(#)tcp.h 8.1 (Berkeley) 6/10/93
30 * $FreeBSD: src/sys/netinet/tcp.h,v 1.40.2.2 2008/07/31 06:10:25 kmacy Exp $
33 #ifndef _NETINET_TCP_H_
34 #define _NETINET_TCP_H_
36 #include <sys/cdefs.h>
38 #define __BSD_VISIBLE 1
42 typedef u_int32_t tcp_seq;
44 #define tcp6_seq tcp_seq /* for KAME src sync over BSD*'s */
45 #define tcp6hdr tcphdr /* for KAME src sync over BSD*'s */
49 * Per RFC 793, September, 1981.
52 u_short th_sport; /* source port */
53 u_short th_dport; /* destination port */
54 tcp_seq th_seq; /* sequence number */
55 tcp_seq th_ack; /* acknowledgement number */
56 #if BYTE_ORDER == LITTLE_ENDIAN
57 u_int th_x2:4, /* (unused) */
58 th_off:4; /* data offset */
60 #if BYTE_ORDER == BIG_ENDIAN
61 u_int th_off:4, /* data offset */
62 th_x2:4; /* (unused) */
73 #define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG|TH_ECE|TH_CWR)
74 #define PRINT_TH_FLAGS "\20\1FIN\2SYN\3RST\4PUSH\5ACK\6URG\7ECE\10CWR"
76 u_short th_win; /* window */
77 u_short th_sum; /* checksum */
78 u_short th_urp; /* urgent pointer */
83 #define TCPOPT_PAD 0 /* padding after EOL */
87 #define TCPOPT_MAXSEG 2
88 #define TCPOLEN_MAXSEG 4
89 #define TCPOPT_WINDOW 3
90 #define TCPOLEN_WINDOW 3
91 #define TCPOPT_SACK_PERMITTED 4
92 #define TCPOLEN_SACK_PERMITTED 2
94 #define TCPOLEN_SACKHDR 2
95 #define TCPOLEN_SACK 8 /* 2*sizeof(tcp_seq) */
96 #define TCPOPT_TIMESTAMP 8
97 #define TCPOLEN_TIMESTAMP 10
98 #define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */
99 #define TCPOPT_SIGNATURE 19 /* Keyed MD5: RFC 2385 */
100 #define TCPOLEN_SIGNATURE 18
102 /* Miscellaneous constants */
103 #define MAX_SACK_BLKS 6 /* Max # SACK blocks stored at receiver side */
104 #define TCP_MAX_SACK 4 /* MAX # SACKs sent in any segment */
108 * Default maximum segment size for TCP.
109 * With an IP MTU of 576, this is 536,
110 * but 512 is probably more convenient.
111 * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
115 * TCP_MINMSS is defined to be 216 which is fine for the smallest
116 * link MTU (256 bytes, AX.25 packet radio) in the Internet.
117 * However it is very unlikely to come across such low MTU interfaces
118 * these days (anno dato 2003).
119 * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments.
120 * Setting this to "0" disables the minmss check.
122 #define TCP_MINMSS 216
125 * Default maximum segment size for TCP6.
126 * With an IP6 MSS of 1280, this is 1220,
127 * but 1024 is probably more convenient. (xxx kazu in doubt)
128 * This should be defined as MIN(1024, IP6_MSS - sizeof (struct tcpip6hdr))
130 #define TCP6_MSS 1024
132 #define TCP_MAXWIN 65535 /* largest value for (unscaled) window */
133 #define TTCP_CLIENT_SND_WND 4096 /* dflt send window for T/TCP client */
135 #define TCP_MAX_WINSHIFT 14 /* maximum window shift */
137 #define TCP_MAXBURST 4 /* maximum segments in a burst */
139 #define TCP_MAXHLEN (0xf<<2) /* max length of header in bytes */
140 #define TCP_MAXOLEN (TCP_MAXHLEN - sizeof(struct tcphdr))
141 /* max space left for options */
142 #endif /* __BSD_VISIBLE */
145 * User-settable options (used with setsockopt).
147 #define TCP_NODELAY 0x01 /* don't delay send to coalesce packets */
149 #define TCP_MAXSEG 0x02 /* set maximum segment size */
150 #define TCP_NOPUSH 0x04 /* don't push last block of write */
151 #define TCP_NOOPT 0x08 /* don't use TCP options */
152 #define TCP_MD5SIG 0x10 /* use MD5 digests (RFC2385) */
153 #define TCP_INFO 0x20 /* retrieve tcp_info structure */
154 #define TCP_CONGESTION 0x40 /* get/set congestion control algorithm */
156 #define TCP_CA_NAME_MAX 16 /* max congestion control name length */
158 #define TCPI_OPT_TIMESTAMPS 0x01
159 #define TCPI_OPT_SACK 0x02
160 #define TCPI_OPT_WSCALE 0x04
161 #define TCPI_OPT_ECN 0x08
162 #define TCPI_OPT_TOE 0x10
165 * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits
166 * the caller to query certain information about the state of a TCP
167 * connection. We provide an overlapping set of fields with the Linux
168 * implementation, but since this is a fixed size structure, room has been
169 * left for growth. In order to maximize potential future compatibility with
170 * the Linux API, the same variable names and order have been adopted, and
171 * padding left to make room for omitted fields in case they are added later.
173 * XXX: This is currently an unstable ABI/API, in that it is expected to
177 u_int8_t tcpi_state; /* TCP FSM state. */
178 u_int8_t __tcpi_ca_state;
179 u_int8_t __tcpi_retransmits;
180 u_int8_t __tcpi_probes;
181 u_int8_t __tcpi_backoff;
182 u_int8_t tcpi_options; /* Options enabled on conn. */
183 u_int8_t tcpi_snd_wscale:4, /* RFC1323 send shift value. */
184 tcpi_rcv_wscale:4; /* RFC1323 recv shift value. */
186 u_int32_t __tcpi_rto;
187 u_int32_t __tcpi_ato;
188 u_int32_t __tcpi_snd_mss;
189 u_int32_t __tcpi_rcv_mss;
191 u_int32_t __tcpi_unacked;
192 u_int32_t __tcpi_sacked;
193 u_int32_t __tcpi_lost;
194 u_int32_t __tcpi_retrans;
195 u_int32_t __tcpi_fackets;
197 /* Times; measurements in usecs. */
198 u_int32_t __tcpi_last_data_sent;
199 u_int32_t __tcpi_last_ack_sent; /* Also unimpl. on Linux? */
200 u_int32_t __tcpi_last_data_recv;
201 u_int32_t __tcpi_last_ack_recv;
203 /* Metrics; variable units. */
204 u_int32_t __tcpi_pmtu;
205 u_int32_t __tcpi_rcv_ssthresh;
206 u_int32_t tcpi_rtt; /* Smoothed RTT in usecs. */
207 u_int32_t tcpi_rttvar; /* RTT variance in usecs. */
208 u_int32_t tcpi_snd_ssthresh; /* Slow start threshold. */
209 u_int32_t tcpi_snd_cwnd; /* Send congestion window. */
210 u_int32_t __tcpi_advmss;
211 u_int32_t __tcpi_reordering;
213 u_int32_t __tcpi_rcv_rtt;
214 u_int32_t tcpi_rcv_space; /* Advertised recv window. */
216 /* FreeBSD extensions to tcp_info. */
217 u_int32_t tcpi_snd_wnd; /* Advertised send window. */
218 u_int32_t tcpi_snd_bwnd; /* Bandwidth send window. */
219 u_int32_t tcpi_snd_nxt; /* Next egress seqno */
220 u_int32_t tcpi_rcv_nxt; /* Next ingress seqno */
221 u_int32_t tcpi_toe_tid; /* HWTID for TOE endpoints */
223 /* Padding to grow without breaking ABI. */
224 u_int32_t __tcpi_pad[29]; /* Padding. */
228 #endif /* !_NETINET_TCP_H_ */