2 * Copyright (c) 1982, 1986, 1993
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33 * @(#)tcp.h 8.1 (Berkeley) 6/10/93
34 * $FreeBSD: src/sys/netinet/tcp.h,v 1.13.2.3 2001/03/01 22:08:42 jlemon Exp $
35 * $DragonFly: src/sys/netinet/tcp.h,v 1.6 2005/01/08 09:50:17 hsu Exp $
38 #ifndef _NETINET_TCP_H_
39 #define _NETINET_TCP_H_
41 typedef u_int32_t tcp_seq;
42 typedef int32_t tcp_seq_diff_t;
43 typedef u_int32_t tcp_cc; /* connection count per rfc1644 */
45 #define tcp6_seq tcp_seq /* for KAME src sync over BSD*'s */
46 #define tcp6hdr tcphdr /* for KAME src sync over BSD*'s */
50 * Per RFC 793, September, 1981.
53 u_short th_sport; /* source port */
54 u_short th_dport; /* destination port */
55 tcp_seq th_seq; /* sequence number */
56 tcp_seq th_ack; /* acknowledgement number */
57 #if _BYTE_ORDER == _LITTLE_ENDIAN
58 u_int th_x2:4, /* (unused) */
59 th_off:4; /* data offset */
60 #elif _BYTE_ORDER == _BIG_ENDIAN
61 u_int th_off:4, /* data offset */
62 th_x2:4; /* (unused) */
64 #error "Byte order not implemented"
75 #define TH_FLAGS (TH_FIN|TH_SYN|TH_RST|TH_ACK|TH_URG|TH_ECE|TH_CWR)
77 u_short th_win; /* window */
78 u_short th_sum; /* checksum */
79 u_short th_urp; /* urgent pointer */
84 #define TCPOPT_2NOPs (TCPOPT_NOP << 24 | TCPOPT_NOP << 16)
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_PERMITTED_ALIGNED \
92 (TCPOPT_2NOPs | TCPOPT_SACK_PERMITTED << 8 | TCPOLEN_SACK_PERMITTED)
93 #define TCPOLEN_SACK_PERMITTED_ALIGNED 4
95 #define TCPOLEN_SACK 2
96 #define TCPOLEN_SACK_BLOCK 8
97 #define TCPOPT_SACK_ALIGNED (TCPOPT_2NOPs | TCPOPT_SACK << 8)
98 #define TCPOLEN_SACK_ALIGNED 4
99 #define TCPOPT_TIMESTAMP 8
100 #define TCPOLEN_TIMESTAMP 10
101 #define TCPOLEN_TSTAMP_APPA (TCPOLEN_TIMESTAMP+2) /* appendix A */
102 #define TCPOPT_TSTAMP_HDR \
103 (TCPOPT_2NOPs | TCPOPT_TIMESTAMP << 8 | TCPOLEN_TIMESTAMP)
104 #define TCPOPT_CC 11 /* CC options: RFC-1644 */
105 #define TCPOPT_CCNEW 12
106 #define TCPOPT_CCECHO 13
108 #define TCPOLEN_CC_APPA (TCPOLEN_CC+2)
109 #define TCPOPT_CC_HDR(ccopt) \
110 (TCPOPT_2NOPs | (ccopt) << 8 | TCPOLEN_CC)
113 * Default maximum segment size for TCP.
114 * With an IP MSS of 576, this is 536,
115 * but 512 is probably more convenient.
116 * This should be defined as MIN(512, IP_MSS - sizeof (struct tcpiphdr)).
117 * The modern consensus is that 1500 is a safe MTU to use for the Internet.
122 * Default maximum segment size for TCP6.
123 * With an IP6 MSS of 1280, this is 1220,
124 * but 1024 is probably more convenient. (xxx kazu in doubt)
125 * This should be defined as MIN(1024, IP6_MSS - sizeof (struct tcpip6hdr))
127 #define TCP6_MSS 1024
129 #define TCP_MAXWIN 65535 /* largest value for (unscaled) window */
130 #define TTCP_CLIENT_SND_WND 4096 /* dflt send window for T/TCP client */
132 #define TCP_MAX_WINSHIFT 14 /* maximum window shift */
134 #define TCP_MAXBURST 4 /* maximum segments in a burst */
136 #define TCP_MAXHLEN (0xf<<2) /* max length of header in bytes */
137 #define TCP_MAXOLEN (TCP_MAXHLEN - sizeof(struct tcphdr))
138 /* max space left for options */
141 * User-settable options (used with setsockopt).
143 #define TCP_NODELAY 0x01 /* don't delay send to coalesce packets */
144 #define TCP_MAXSEG 0x02 /* set maximum segment size */
145 #define TCP_NOPUSH 0x04 /* don't push last block of write */
146 #define TCP_NOOPT 0x08 /* don't use TCP options */