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/* $Id: tcp_var.h $ */
/** @file
* NAT - TCP (declarations).
*/
/*
* Copyright (C) 2006-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* SPDX-License-Identifier: GPL-3.0-only
*/
/*
* This code is based on:
*
* Copyright (c) 1982, 1986, 1993, 1994
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)tcp_var.h 8.3 (Berkeley) 4/10/94
* tcp_var.h,v 1.3 1994/08/21 05:27:39 paul Exp
*/
#ifndef _TCP_VAR_H_
#define _TCP_VAR_H_
#include "queue.h"
#include "tcpip.h"
#include "tcp_timer.h"
/* TCP segment queue entry */
struct tseg_qent
{
LIST_ENTRY(tseg_qent) tqe_q;
int tqe_len; /* TCP segment data length */
struct tcphdr *tqe_th; /* a pointer to tcp header */
struct mbuf *tqe_m; /* mbuf contains packet */
};
LIST_HEAD(tsegqe_head, tseg_qent);
/*
* Tcp control block, one per tcp; fields:
*/
struct tcpcb
{
LIST_ENTRY(tcpcb) t_list;
struct tsegqe_head t_segq; /* segment reassembly queue */
int t_segqlen; /* segment reassembly queue length */
int16_t t_state; /* state of this connection */
int16_t t_timer[TCPT_NTIMERS]; /* tcp timers */
int16_t t_rxtshift; /* log(2) of rexmt exp. backoff */
int16_t t_rxtcur; /* current retransmit value */
int16_t t_dupacks; /* consecutive dup acks recd */
uint16_t t_maxseg; /* maximum segment size */
char t_force; /* 1 if forcing out a byte */
uint16_t t_flags;
#define TF_ACKNOW 0x0001 /* ack peer immediately */
#define TF_DELACK 0x0002 /* ack, but try to delay it */
#define TF_NODELAY 0x0004 /* don't delay packets to coalesce */
#define TF_NOOPT 0x0008 /* don't use tcp options */
#define TF_SENTFIN 0x0010 /* have sent FIN */
#define TF_REQ_SCALE 0x0020 /* have/will request window scaling */
#define TF_RCVD_SCALE 0x0040 /* other side has requested scaling */
#define TF_REQ_TSTMP 0x0080 /* have/will request timestamps */
#define TF_RCVD_TSTMP 0x0100 /* a timestamp was received in SYN */
#define TF_SACK_PERMIT 0x0200 /* other side said I could SACK */
/* Make it static for now */
/* struct tcpiphdr *t_template; / * skeletal packet for transmit */
struct tcpiphdr t_template;
struct socket *t_socket; /* back pointer to socket */
/*
* The following fields are used as in the protocol specification.
* See RFC783, Dec. 1981, page 21.
*/
/* send sequence variables */
tcp_seq snd_una; /* send unacknowledged */
tcp_seq snd_nxt; /* send next */
tcp_seq snd_up; /* send urgent pointer */
tcp_seq snd_wl1; /* window update seg seq number */
tcp_seq snd_wl2; /* window update seg ack number */
tcp_seq iss; /* initial send sequence number */
uint32_t snd_wnd; /* send window */
/* receive sequence variables */
uint32_t rcv_wnd; /* receive window */
tcp_seq rcv_nxt; /* receive next */
tcp_seq rcv_up; /* receive urgent pointer */
tcp_seq irs; /* initial receive sequence number */
/*
* Additional variables for this implementation.
*/
/* receive variables */
tcp_seq rcv_adv; /* advertised window */
/* retransmit variables */
tcp_seq snd_max; /* highest sequence number sent;
* used to recognize retransmits
*/
/* congestion control (for slow start, source quench, retransmit after loss) */
uint32_t snd_cwnd; /* congestion-controlled window */
uint32_t snd_ssthresh; /* snd_cwnd size threshold for
* for slow start exponential to
* linear switch
*/
/*
* transmit timing stuff. See below for scale of srtt and rttvar.
* "Variance" is actually smoothed difference.
*/
int16_t t_idle; /* inactivity time */
int16_t t_rtt; /* round trip time */
tcp_seq t_rtseq; /* sequence number being timed */
int16_t t_srtt; /* smoothed round-trip time */
int16_t t_rttvar; /* variance in round-trip time */
uint16_t t_rttmin; /* minimum rtt allowed */
uint32_t max_sndwnd; /* largest window peer has offered */
/* out-of-band data */
char t_oobflags; /* have some */
char t_iobc; /* input character */
#define TCPOOB_HAVEDATA 0x01
#define TCPOOB_HADDATA 0x02
short t_softerror; /* possible error not yet reported */
/* RFC 1323 variables */
uint8_t snd_scale; /* window scaling for send window */
uint8_t rcv_scale; /* window scaling for recv window */
uint8_t request_r_scale; /* pending window scaling */
uint8_t requested_s_scale;
uint32_t ts_recent; /* timestamp echo data */
uint32_t ts_recent_age; /* when last updated */
tcp_seq last_ack_sent;
};
LIST_HEAD(tcpcbhead, tcpcb);
#define sototcpcb(so) ((so)->so_tcpcb)
/*
* The smoothed round-trip time and estimated variance
* are stored as fixed point numbers scaled by the values below.
* For convenience, these scales are also used in smoothing the average
* (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
* With these scales, srtt has 3 bits to the right of the binary point,
* and thus an "ALPHA" of 0.875. rttvar has 2 bits to the right of the
* binary point, and is smoothed with an ALPHA of 0.75.
*/
#define TCP_RTT_SCALE 8 /* multiplier for srtt; 3 bits frac. */
#define TCP_RTT_SHIFT 3 /* shift for srtt; 3 bits frac. */
#define TCP_RTTVAR_SCALE 4 /* multiplier for rttvar; 2 bits */
#define TCP_RTTVAR_SHIFT 2 /* multiplier for rttvar; 2 bits */
/*
* The initial retransmission should happen at rtt + 4 * rttvar.
* Because of the way we do the smoothing, srtt and rttvar
* will each average +1/2 tick of bias. When we compute
* the retransmit timer, we want 1/2 tick of rounding and
* 1 extra tick because of +-1/2 tick uncertainty in the
* firing of the timer. The bias will give us exactly the
* 1.5 tick we need. But, because the bias is
* statistical, we have to test that we don't drop below
* the minimum feasible timer (which is 2 ticks).
* This macro assumes that the value of TCP_RTTVAR_SCALE
* is the same as the multiplier for rttvar.
*/
#define TCP_REXMTVAL(tp) \
(((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar)
/*
* TCP statistics.
* Many of these should be kept per connection,
* but that's inconvenient at the moment.
*/
struct tcpstat_t
{
u_long tcps_connattempt; /* connections initiated */
u_long tcps_accepts; /* connections accepted */
u_long tcps_connects; /* connections established */
u_long tcps_drops; /* connections dropped */
u_long tcps_conndrops; /* embryonic connections dropped */
u_long tcps_closed; /* conn. closed (includes drops) */
u_long tcps_segstimed; /* segs where we tried to get rtt */
u_long tcps_rttupdated; /* times we succeeded */
u_long tcps_delack; /* delayed acks sent */
u_long tcps_timeoutdrop; /* conn. dropped in rxmt timeout */
u_long tcps_rexmttimeo; /* retransmit timeouts */
u_long tcps_persisttimeo; /* persist timeouts */
u_long tcps_keeptimeo; /* keepalive timeouts */
u_long tcps_keepprobe; /* keepalive probes sent */
u_long tcps_keepdrops; /* connections dropped in keepalive */
u_long tcps_sndtotal; /* total packets sent */
u_long tcps_sndpack; /* data packets sent */
u_long tcps_sndbyte; /* data bytes sent */
u_long tcps_sndrexmitpack; /* data packets retransmitted */
u_long tcps_sndrexmitbyte; /* data bytes retransmitted */
u_long tcps_sndacks; /* ack-only packets sent */
u_long tcps_sndprobe; /* window probes sent */
u_long tcps_sndurg; /* packets sent with URG only */
u_long tcps_sndwinup; /* window update-only packets sent */
u_long tcps_sndctrl; /* control (SYN|FIN|RST) packets sent */
u_long tcps_rcvtotal; /* total packets received */
u_long tcps_rcvpack; /* packets received in sequence */
u_long tcps_rcvbyte; /* bytes received in sequence */
u_long tcps_rcvbadsum; /* packets received with ccksum errs */
u_long tcps_rcvbadoff; /* packets received with bad offset */
/* u_long tcps_rcvshort; */ /* packets received too short */
u_long tcps_rcvduppack; /* duplicate-only packets received */
u_long tcps_rcvdupbyte; /* duplicate-only bytes received */
u_long tcps_rcvpartduppack; /* packets with some duplicate data */
u_long tcps_rcvpartdupbyte; /* dup. bytes in part-dup. packets */
u_long tcps_rcvoopack; /* out-of-order packets received */
u_long tcps_rcvoobyte; /* out-of-order bytes received */
u_long tcps_rcvpackafterwin; /* packets with data after window */
u_long tcps_rcvbyteafterwin; /* bytes rcvd after window */
u_long tcps_rcvafterclose; /* packets rcvd after "close" */
u_long tcps_rcvwinprobe; /* rcvd window probe packets */
u_long tcps_rcvdupack; /* rcvd duplicate acks */
u_long tcps_rcvacktoomuch; /* rcvd acks for unsent data */
u_long tcps_rcvackpack; /* rcvd ack packets */
u_long tcps_rcvackbyte; /* bytes acked by rcvd acks */
u_long tcps_rcvwinupd; /* rcvd window update packets */
/* u_long tcps_pawsdrop; */ /* segments dropped due to PAWS */
u_long tcps_predack; /* times hdr predict ok for acks */
u_long tcps_preddat; /* times hdr predict ok for data pkts */
u_long tcps_socachemiss; /* tcp_last_so misses */
u_long tcps_didnuttin; /* Times tcp_output didn't do anything XXX */
u_long tcps_rcvmemdrop;
};
#endif
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