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29 * @(#)tcp.h 8.1 (Berkeley) 6/10/93
33 #ifndef _NETINET_TCP_H_
34 #define _NETINET_TCP_H_
36 #include <sys/cdefs.h>
40 typedef u_int32_t tcp_seq;
42 #define tcp6_seq tcp_seq /* for KAME src sync over BSD*'s */
43 #define tcp6hdr tcphdr /* for KAME src sync over BSD*'s */
47 * Per RFC 793, September, 1981.
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 */
58 #if BYTE_ORDER == BIG_ENDIAN
59 u_int th_off:4, /* data offset */
60 th_x2:4; /* (unused) */
71 #define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG|TH_ECE|TH_CWR)
73 u_short th_win; /* window */
74 u_short th_sum; /* checksum */
75 u_short th_urp; /* urgent pointer */
80 #define TCPOPT_MAXSEG 2
81 #define TCPOLEN_MAXSEG 4
82 #define TCPOPT_WINDOW 3
83 #define TCPOLEN_WINDOW 3
84 #define TCPOPT_SACK_PERMITTED 4 /* Experimental */
85 #define TCPOLEN_SACK_PERMITTED 2
86 #define TCPOPT_SACK 5 /* Experimental */
87 #define TCPOLEN_SACK 8 /* 2*sizeof(tcp_seq) */
88 #define TCPOPT_TIMESTAMP 8
89 #define TCPOLEN_TIMESTAMP 10
90 #define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */
91 #define TCPOPT_TSTAMP_HDR \
92 (TCPOPT_NOP<<24|TCPOPT_NOP<<16|TCPOPT_TIMESTAMP<<8|TCPOLEN_TIMESTAMP)
94 #define MAX_TCPOPTLEN 40 /* Absolute maximum TCP options len */
96 #define TCPOPT_SIGNATURE 19 /* Keyed MD5: RFC 2385 */
97 #define TCPOLEN_SIGNATURE 18
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 receiver side */
105 #define TCP_MAX_SACK 4 /* MAX # SACKs sent in any segment */
109 * Default maximum segment size for TCP.
110 * With an IP MTU 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)).
116 * TCP_MINMSS is defined to be 216 which is fine for the smallest
117 * link MTU (256 bytes, AX.25 packet radio) in the Internet.
118 * However it is very unlikely to come across such low MTU interfaces
119 * these days (anno dato 2003).
120 * See tcp_subr.c tcp_minmss SYSCTL declaration for more comments.
121 * Setting this to "0" disables the minmss check.
123 #define TCP_MINMSS 216
125 * TCP_MINMSSOVERLOAD is defined to be 1000 which should cover any type
126 * of interactive TCP session.
127 * See tcp_subr.c tcp_minmssoverload SYSCTL declaration and tcp_input.c
129 * Setting this to "0" disables the minmssoverload check.
131 #define TCP_MINMSSOVERLOAD 0 /* XXX: Disabled until refined */
134 * Default maximum segment size for TCP6.
135 * With an IP6 MSS of 1280, this is 1220,
136 * but 1024 is probably more convenient. (xxx kazu in doubt)
137 * This should be defined as MIN(1024, IP6_MSS - sizeof (struct tcpip6hdr))
139 #define TCP6_MSS 1024
141 #define TCP_MAXWIN 65535 /* largest value for (unscaled) window */
142 #define TTCP_CLIENT_SND_WND 4096 /* dflt send window for T/TCP client */
144 #define TCP_MAX_WINSHIFT 14 /* maximum window shift */
146 #define TCP_MAXBURST 4 /* maximum segments in a burst */
148 #define TCP_MAXHLEN (0xf<<2) /* max length of header in bytes */
149 #define TCP_MAXOLEN (TCP_MAXHLEN - sizeof(struct tcphdr))
150 /* max space left for options */
151 #endif /* __BSD_VISIBLE */
154 * User-settable options (used with setsockopt).
156 #define TCP_NODELAY 0x01 /* don't delay send to coalesce packets */
158 #define TCP_MAXSEG 0x02 /* set maximum segment size */
159 #define TCP_NOPUSH 0x04 /* don't push last block of write */
160 #define TCP_NOOPT 0x08 /* don't use TCP options */
161 #define TCP_MD5SIG 0x10 /* use MD5 digests (RFC2385) */
162 #define TCP_INFO 0x20 /* retrieve tcp_info structure */
164 #define TCPI_OPT_TIMESTAMPS 0x01
165 #define TCPI_OPT_SACK 0x02
166 #define TCPI_OPT_WSCALE 0x04
167 #define TCPI_OPT_ECN 0x08
170 * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits
171 * the caller to query certain information about the state of a TCP
172 * connection. We provide an overlapping set of fields with the Linux
173 * implementation, but since this is a fixed size structure, room has been
174 * left for growth. In order to maximize potential future compatibility with
175 * the Linux API, the same variable names and order have been adopted, and
176 * padding left to make room for omitted fields in case they are added later.
178 * XXX: This is currently an unstable ABI/API, in that it is expected to
182 u_int8_t tcpi_state; /* TCP FSM state. */
183 u_int8_t __tcpi_ca_state;
184 u_int8_t __tcpi_retransmits;
185 u_int8_t __tcpi_probes;
186 u_int8_t __tcpi_backoff;
187 u_int8_t tcpi_options; /* Options enabled on conn. */
188 u_int8_t tcpi_snd_wscale:4, /* RFC1323 send shift value. */
189 tcpi_rcv_wscale:4; /* RFC1323 recv shift value. */
191 u_int32_t __tcpi_rto;
192 u_int32_t __tcpi_ato;
193 u_int32_t __tcpi_snd_mss;
194 u_int32_t __tcpi_rcv_mss;
196 u_int32_t __tcpi_unacked;
197 u_int32_t __tcpi_sacked;
198 u_int32_t __tcpi_lost;
199 u_int32_t __tcpi_retrans;
200 u_int32_t __tcpi_fackets;
202 /* Times; measurements in usecs. */
203 u_int32_t __tcpi_last_data_sent;
204 u_int32_t __tcpi_last_ack_sent; /* Also unimpl. on Linux? */
205 u_int32_t __tcpi_last_data_recv;
206 u_int32_t __tcpi_last_ack_recv;
208 /* Metrics; variable units. */
209 u_int32_t __tcpi_pmtu;
210 u_int32_t __tcpi_rcv_ssthresh;
211 u_int32_t __tcpi_rtt;
212 u_int32_t __tcpi_rttvar;
213 u_int32_t tcpi_snd_ssthresh; /* Slow start threshold. */
214 u_int32_t tcpi_snd_cwnd; /* Send congestion window. */
215 u_int32_t __tcpi_advmss;
216 u_int32_t __tcpi_reordering;
218 u_int32_t __tcpi_rcv_rtt;
219 u_int32_t tcpi_rcv_space; /* Advertised recv window. */
221 /* FreeBSD extensions to tcp_info. */
222 u_int32_t tcpi_snd_wnd; /* Advertised send window. */
223 u_int32_t tcpi_snd_bwnd; /* Bandwidth send window. */
225 /* Padding to grow without breaking ABI. */
226 u_int32_t __tcpi_pad[32]; /* Padding. */
230 #endif /* !_NETINET_TCP_H_ */