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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)
72 #define PRINT_TH_FLAGS "\20\1FIN\2SYN\3RST\4PUSH\5ACK\6URG\7ECE\10CWR"
74 u_short th_win; /* window */
75 u_short th_sum; /* checksum */
76 u_short th_urp; /* urgent pointer */
81 #define TCPOPT_PAD 0 /* padding after EOL */
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
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
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 */
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)).
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 "0" disables the minmss check.
120 #define TCP_MINMSS 216
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))
128 #define TCP6_MSS 1024
130 #define TCP_MAXWIN 65535 /* largest value for (unscaled) window */
131 #define TTCP_CLIENT_SND_WND 4096 /* dflt send window for T/TCP client */
133 #define TCP_MAX_WINSHIFT 14 /* maximum window shift */
135 #define TCP_MAXBURST 4 /* maximum segments in a burst */
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 */
143 * User-settable options (used with setsockopt).
145 #define TCP_NODELAY 0x01 /* don't delay send to coalesce packets */
147 #define TCP_MAXSEG 0x02 /* set maximum segment size */
148 #define TCP_NOPUSH 0x04 /* don't push last block of write */
149 #define TCP_NOOPT 0x08 /* don't use TCP options */
150 #define TCP_MD5SIG 0x10 /* use MD5 digests (RFC2385) */
151 #define TCP_INFO 0x20 /* retrieve tcp_info structure */
152 #define TCP_CONGESTION 0x40 /* get/set congestion control algorithm */
154 #define TCP_CA_NAME_MAX 16 /* max congestion control name length */
156 #define TCPI_OPT_TIMESTAMPS 0x01
157 #define TCPI_OPT_SACK 0x02
158 #define TCPI_OPT_WSCALE 0x04
159 #define TCPI_OPT_ECN 0x08
160 #define TCPI_OPT_TOE 0x10
163 * The TCP_INFO socket option comes from the Linux 2.6 TCP API, and permits
164 * the caller to query certain information about the state of a TCP
165 * connection. We provide an overlapping set of fields with the Linux
166 * implementation, but since this is a fixed size structure, room has been
167 * left for growth. In order to maximize potential future compatibility with
168 * the Linux API, the same variable names and order have been adopted, and
169 * padding left to make room for omitted fields in case they are added later.
171 * XXX: This is currently an unstable ABI/API, in that it is expected to
175 u_int8_t tcpi_state; /* TCP FSM state. */
176 u_int8_t __tcpi_ca_state;
177 u_int8_t __tcpi_retransmits;
178 u_int8_t __tcpi_probes;
179 u_int8_t __tcpi_backoff;
180 u_int8_t tcpi_options; /* Options enabled on conn. */
181 u_int8_t tcpi_snd_wscale:4, /* RFC1323 send shift value. */
182 tcpi_rcv_wscale:4; /* RFC1323 recv shift value. */
184 u_int32_t tcpi_rto; /* Retransmission timeout (usec). */
185 u_int32_t __tcpi_ato;
186 u_int32_t tcpi_snd_mss; /* Max segment size for send. */
187 u_int32_t tcpi_rcv_mss; /* Max segment size for receive. */
189 u_int32_t __tcpi_unacked;
190 u_int32_t __tcpi_sacked;
191 u_int32_t __tcpi_lost;
192 u_int32_t __tcpi_retrans;
193 u_int32_t __tcpi_fackets;
195 /* Times; measurements in usecs. */
196 u_int32_t __tcpi_last_data_sent;
197 u_int32_t __tcpi_last_ack_sent; /* Also unimpl. on Linux? */
198 u_int32_t tcpi_last_data_recv; /* Time since last recv data. */
199 u_int32_t __tcpi_last_ack_recv;
201 /* Metrics; variable units. */
202 u_int32_t __tcpi_pmtu;
203 u_int32_t __tcpi_rcv_ssthresh;
204 u_int32_t tcpi_rtt; /* Smoothed RTT in usecs. */
205 u_int32_t tcpi_rttvar; /* RTT variance in usecs. */
206 u_int32_t tcpi_snd_ssthresh; /* Slow start threshold. */
207 u_int32_t tcpi_snd_cwnd; /* Send congestion window. */
208 u_int32_t __tcpi_advmss;
209 u_int32_t __tcpi_reordering;
211 u_int32_t __tcpi_rcv_rtt;
212 u_int32_t tcpi_rcv_space; /* Advertised recv window. */
214 /* FreeBSD extensions to tcp_info. */
215 u_int32_t tcpi_snd_wnd; /* Advertised send window. */
216 u_int32_t tcpi_snd_bwnd; /* Bandwidth send window. */
217 u_int32_t tcpi_snd_nxt; /* Next egress seqno */
218 u_int32_t tcpi_rcv_nxt; /* Next ingress seqno */
219 u_int32_t tcpi_toe_tid; /* HWTID for TOE endpoints */
220 u_int32_t tcpi_snd_rexmitpack; /* Retransmitted packets */
221 u_int32_t tcpi_rcv_ooopack; /* Out-of-order packets */
222 u_int32_t tcpi_snd_zerowin; /* Zero-sized windows sent */
224 /* Padding to grow without breaking ABI. */
225 u_int32_t __tcpi_pad[26]; /* Padding. */
229 #endif /* !_NETINET_TCP_H_ */