tests: virtio-9p: add version operation test
[qemu.git] / slirp / tcp_var.h
1 /*
2 * Copyright (c) 1982, 1986, 1993, 1994
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 * 3. 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_var.h 8.3 (Berkeley) 4/10/94
30 * tcp_var.h,v 1.3 1994/08/21 05:27:39 paul Exp
31 */
32
33 #ifndef TCP_VAR_H
34 #define TCP_VAR_H
35
36 #include "tcpip.h"
37 #include "tcp_timer.h"
38
39 /*
40 * Tcp control block, one per tcp; fields:
41 */
42 struct tcpcb {
43 struct tcpiphdr *seg_next; /* sequencing queue */
44 struct tcpiphdr *seg_prev;
45 short t_state; /* state of this connection */
46 short t_timer[TCPT_NTIMERS]; /* tcp timers */
47 short t_rxtshift; /* log(2) of rexmt exp. backoff */
48 short t_rxtcur; /* current retransmit value */
49 short t_dupacks; /* consecutive dup acks recd */
50 u_short t_maxseg; /* maximum segment size */
51 char t_force; /* 1 if forcing out a byte */
52 u_short t_flags;
53 #define TF_ACKNOW 0x0001 /* ack peer immediately */
54 #define TF_DELACK 0x0002 /* ack, but try to delay it */
55 #define TF_NODELAY 0x0004 /* don't delay packets to coalesce */
56 #define TF_NOOPT 0x0008 /* don't use tcp options */
57 #define TF_SENTFIN 0x0010 /* have sent FIN */
58 #define TF_REQ_SCALE 0x0020 /* have/will request window scaling */
59 #define TF_RCVD_SCALE 0x0040 /* other side has requested scaling */
60 #define TF_REQ_TSTMP 0x0080 /* have/will request timestamps */
61 #define TF_RCVD_TSTMP 0x0100 /* a timestamp was received in SYN */
62 #define TF_SACK_PERMIT 0x0200 /* other side said I could SACK */
63
64 struct tcpiphdr t_template; /* static skeletal packet for xmit */
65
66 struct socket *t_socket; /* back pointer to socket */
67 /*
68 * The following fields are used as in the protocol specification.
69 * See RFC783, Dec. 1981, page 21.
70 */
71 /* send sequence variables */
72 tcp_seq snd_una; /* send unacknowledged */
73 tcp_seq snd_nxt; /* send next */
74 tcp_seq snd_up; /* send urgent pointer */
75 tcp_seq snd_wl1; /* window update seg seq number */
76 tcp_seq snd_wl2; /* window update seg ack number */
77 tcp_seq iss; /* initial send sequence number */
78 uint32_t snd_wnd; /* send window */
79 /* receive sequence variables */
80 uint32_t rcv_wnd; /* receive window */
81 tcp_seq rcv_nxt; /* receive next */
82 tcp_seq rcv_up; /* receive urgent pointer */
83 tcp_seq irs; /* initial receive sequence number */
84 /*
85 * Additional variables for this implementation.
86 */
87 /* receive variables */
88 tcp_seq rcv_adv; /* advertised window */
89 /* retransmit variables */
90 tcp_seq snd_max; /* highest sequence number sent;
91 * used to recognize retransmits
92 */
93 /* congestion control (for slow start, source quench, retransmit after loss) */
94 uint32_t snd_cwnd; /* congestion-controlled window */
95 uint32_t snd_ssthresh; /* snd_cwnd size threshold for
96 * for slow start exponential to
97 * linear switch
98 */
99 /*
100 * transmit timing stuff. See below for scale of srtt and rttvar.
101 * "Variance" is actually smoothed difference.
102 */
103 short t_idle; /* inactivity time */
104 short t_rtt; /* round trip time */
105 tcp_seq t_rtseq; /* sequence number being timed */
106 short t_srtt; /* smoothed round-trip time */
107 short t_rttvar; /* variance in round-trip time */
108 u_short t_rttmin; /* minimum rtt allowed */
109 uint32_t max_sndwnd; /* largest window peer has offered */
110
111 /* out-of-band data */
112 char t_oobflags; /* have some */
113 char t_iobc; /* input character */
114 #define TCPOOB_HAVEDATA 0x01
115 #define TCPOOB_HADDATA 0x02
116 short t_softerror; /* possible error not yet reported */
117
118 /* RFC 1323 variables */
119 u_char snd_scale; /* window scaling for send window */
120 u_char rcv_scale; /* window scaling for recv window */
121 u_char request_r_scale; /* pending window scaling */
122 u_char requested_s_scale;
123 uint32_t ts_recent; /* timestamp echo data */
124 uint32_t ts_recent_age; /* when last updated */
125 tcp_seq last_ack_sent;
126
127 };
128
129 #define sototcpcb(so) ((so)->so_tcpcb)
130
131 /*
132 * The smoothed round-trip time and estimated variance
133 * are stored as fixed point numbers scaled by the values below.
134 * For convenience, these scales are also used in smoothing the average
135 * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
136 * With these scales, srtt has 3 bits to the right of the binary point,
137 * and thus an "ALPHA" of 0.875. rttvar has 2 bits to the right of the
138 * binary point, and is smoothed with an ALPHA of 0.75.
139 */
140 #define TCP_RTT_SCALE 8 /* multiplier for srtt; 3 bits frac. */
141 #define TCP_RTT_SHIFT 3 /* shift for srtt; 3 bits frac. */
142 #define TCP_RTTVAR_SCALE 4 /* multiplier for rttvar; 2 bits */
143 #define TCP_RTTVAR_SHIFT 2 /* multiplier for rttvar; 2 bits */
144
145 /*
146 * The initial retransmission should happen at rtt + 4 * rttvar.
147 * Because of the way we do the smoothing, srtt and rttvar
148 * will each average +1/2 tick of bias. When we compute
149 * the retransmit timer, we want 1/2 tick of rounding and
150 * 1 extra tick because of +-1/2 tick uncertainty in the
151 * firing of the timer. The bias will give us exactly the
152 * 1.5 tick we need. But, because the bias is
153 * statistical, we have to test that we don't drop below
154 * the minimum feasible timer (which is 2 ticks).
155 * This macro assumes that the value of TCP_RTTVAR_SCALE
156 * is the same as the multiplier for rttvar.
157 */
158 #define TCP_REXMTVAL(tp) \
159 (((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar)
160
161 #endif