460fec67ee
The essence of this patch is to stuff (almost) all global variables of the slirp stack into the structure Slirp. In this step, we still keep the structure as global variable, directly accessible by the whole stack. Changes to the external interface of slirp will be applied in the following patches. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
162 lines
6.5 KiB
C
162 lines
6.5 KiB
C
/*
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* Copyright (c) 1982, 1986, 1993, 1994
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)tcp_var.h 8.3 (Berkeley) 4/10/94
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* tcp_var.h,v 1.3 1994/08/21 05:27:39 paul Exp
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*/
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#ifndef _TCP_VAR_H_
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#define _TCP_VAR_H_
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#include "tcpip.h"
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#include "tcp_timer.h"
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/*
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* Tcp control block, one per tcp; fields:
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*/
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struct tcpcb {
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struct tcpiphdr *seg_next; /* sequencing queue */
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struct tcpiphdr *seg_prev;
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short t_state; /* state of this connection */
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short t_timer[TCPT_NTIMERS]; /* tcp timers */
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short t_rxtshift; /* log(2) of rexmt exp. backoff */
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short t_rxtcur; /* current retransmit value */
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short t_dupacks; /* consecutive dup acks recd */
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u_short t_maxseg; /* maximum segment size */
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char t_force; /* 1 if forcing out a byte */
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u_short t_flags;
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#define TF_ACKNOW 0x0001 /* ack peer immediately */
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#define TF_DELACK 0x0002 /* ack, but try to delay it */
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#define TF_NODELAY 0x0004 /* don't delay packets to coalesce */
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#define TF_NOOPT 0x0008 /* don't use tcp options */
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#define TF_SENTFIN 0x0010 /* have sent FIN */
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#define TF_REQ_SCALE 0x0020 /* have/will request window scaling */
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#define TF_RCVD_SCALE 0x0040 /* other side has requested scaling */
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#define TF_REQ_TSTMP 0x0080 /* have/will request timestamps */
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#define TF_RCVD_TSTMP 0x0100 /* a timestamp was received in SYN */
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#define TF_SACK_PERMIT 0x0200 /* other side said I could SACK */
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struct tcpiphdr t_template; /* static skeletal packet for xmit */
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struct socket *t_socket; /* back pointer to socket */
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/*
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* The following fields are used as in the protocol specification.
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* See RFC783, Dec. 1981, page 21.
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*/
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/* send sequence variables */
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tcp_seq snd_una; /* send unacknowledged */
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tcp_seq snd_nxt; /* send next */
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tcp_seq snd_up; /* send urgent pointer */
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tcp_seq snd_wl1; /* window update seg seq number */
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tcp_seq snd_wl2; /* window update seg ack number */
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tcp_seq iss; /* initial send sequence number */
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u_int32_t snd_wnd; /* send window */
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/* receive sequence variables */
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u_int32_t rcv_wnd; /* receive window */
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tcp_seq rcv_nxt; /* receive next */
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tcp_seq rcv_up; /* receive urgent pointer */
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tcp_seq irs; /* initial receive sequence number */
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/*
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* Additional variables for this implementation.
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*/
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/* receive variables */
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tcp_seq rcv_adv; /* advertised window */
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/* retransmit variables */
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tcp_seq snd_max; /* highest sequence number sent;
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* used to recognize retransmits
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*/
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/* congestion control (for slow start, source quench, retransmit after loss) */
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u_int32_t snd_cwnd; /* congestion-controlled window */
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u_int32_t snd_ssthresh; /* snd_cwnd size threshold for
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* for slow start exponential to
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* linear switch
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*/
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/*
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* transmit timing stuff. See below for scale of srtt and rttvar.
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* "Variance" is actually smoothed difference.
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*/
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short t_idle; /* inactivity time */
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short t_rtt; /* round trip time */
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tcp_seq t_rtseq; /* sequence number being timed */
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short t_srtt; /* smoothed round-trip time */
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short t_rttvar; /* variance in round-trip time */
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u_short t_rttmin; /* minimum rtt allowed */
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u_int32_t max_sndwnd; /* largest window peer has offered */
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/* out-of-band data */
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char t_oobflags; /* have some */
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char t_iobc; /* input character */
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#define TCPOOB_HAVEDATA 0x01
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#define TCPOOB_HADDATA 0x02
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short t_softerror; /* possible error not yet reported */
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/* RFC 1323 variables */
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u_char snd_scale; /* window scaling for send window */
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u_char rcv_scale; /* window scaling for recv window */
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u_char request_r_scale; /* pending window scaling */
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u_char requested_s_scale;
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u_int32_t ts_recent; /* timestamp echo data */
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u_int32_t ts_recent_age; /* when last updated */
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tcp_seq last_ack_sent;
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};
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#define sototcpcb(so) ((so)->so_tcpcb)
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/*
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* The smoothed round-trip time and estimated variance
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* are stored as fixed point numbers scaled by the values below.
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* For convenience, these scales are also used in smoothing the average
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* (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
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* With these scales, srtt has 3 bits to the right of the binary point,
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* and thus an "ALPHA" of 0.875. rttvar has 2 bits to the right of the
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* binary point, and is smoothed with an ALPHA of 0.75.
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*/
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#define TCP_RTT_SCALE 8 /* multiplier for srtt; 3 bits frac. */
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#define TCP_RTT_SHIFT 3 /* shift for srtt; 3 bits frac. */
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#define TCP_RTTVAR_SCALE 4 /* multiplier for rttvar; 2 bits */
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#define TCP_RTTVAR_SHIFT 2 /* multiplier for rttvar; 2 bits */
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/*
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* The initial retransmission should happen at rtt + 4 * rttvar.
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* Because of the way we do the smoothing, srtt and rttvar
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* will each average +1/2 tick of bias. When we compute
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* the retransmit timer, we want 1/2 tick of rounding and
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* 1 extra tick because of +-1/2 tick uncertainty in the
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* firing of the timer. The bias will give us exactly the
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* 1.5 tick we need. But, because the bias is
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* statistical, we have to test that we don't drop below
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* the minimum feasible timer (which is 2 ticks).
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* This macro assumes that the value of TCP_RTTVAR_SCALE
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* is the same as the multiplier for rttvar.
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*/
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#define TCP_REXMTVAL(tp) \
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(((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar)
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#endif
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