root / slirp / tcp_var.h @ 460fec67
History | View | Annotate | Download (6.5 kB)
| 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 |
u_int32_t snd_wnd; /* send window */
|
| 79 |
/* receive sequence variables */
|
| 80 |
u_int32_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 |
u_int32_t snd_cwnd; /* congestion-controlled window */
|
| 95 |
u_int32_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 |
u_int32_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 |
u_int32_t ts_recent; /* timestamp echo data */
|
| 124 |
u_int32_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
|