| 1 | /* $Id: tcp_var.h 98103 2023-01-17 14:15:46Z vboxsync $ */
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| 2 | /** @file
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| 3 | * NAT - TCP (declarations).
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2006-2023 Oracle and/or its affiliates.
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| 8 | *
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| 9 | * This file is part of VirtualBox base platform packages, as
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| 10 | * available from https://www.virtualbox.org.
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| 11 | *
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| 12 | * This program is free software; you can redistribute it and/or
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| 13 | * modify it under the terms of the GNU General Public License
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| 14 | * as published by the Free Software Foundation, in version 3 of the
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| 15 | * License.
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| 16 | *
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| 17 | * This program is distributed in the hope that it will be useful, but
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| 18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 20 | * General Public License for more details.
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| 21 | *
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| 22 | * You should have received a copy of the GNU General Public License
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| 23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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| 24 | *
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| 25 | * SPDX-License-Identifier: GPL-3.0-only
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| 26 | */
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| 27 |
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| 28 | /*
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| 29 | * This code is based on:
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| 30 | *
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| 31 | * Copyright (c) 1982, 1986, 1993, 1994
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| 32 | * The Regents of the University of California. All rights reserved.
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| 33 | *
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| 34 | * Redistribution and use in source and binary forms, with or without
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| 35 | * modification, are permitted provided that the following conditions
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| 36 | * are met:
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| 37 | * 1. Redistributions of source code must retain the above copyright
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| 38 | * notice, this list of conditions and the following disclaimer.
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| 39 | * 2. Redistributions in binary form must reproduce the above copyright
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| 40 | * notice, this list of conditions and the following disclaimer in the
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| 41 | * documentation and/or other materials provided with the distribution.
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| 42 | * 3. Neither the name of the University nor the names of its contributors
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| 43 | * may be used to endorse or promote products derived from this software
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| 44 | * without specific prior written permission.
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| 45 | *
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| 46 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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| 47 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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| 48 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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| 49 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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| 50 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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| 51 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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| 52 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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| 53 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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| 54 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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| 55 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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| 56 | * SUCH DAMAGE.
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| 57 | *
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| 58 | * @(#)tcp_var.h 8.3 (Berkeley) 4/10/94
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| 59 | * tcp_var.h,v 1.3 1994/08/21 05:27:39 paul Exp
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| 60 | */
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| 61 |
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| 62 | #ifndef _TCP_VAR_H_
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| 63 | #define _TCP_VAR_H_
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| 64 |
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| 65 | #include "queue.h"
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| 66 | #include "tcpip.h"
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| 67 | #include "tcp_timer.h"
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| 68 |
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| 69 | /* TCP segment queue entry */
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| 70 | struct tseg_qent
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| 71 | {
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| 72 | LIST_ENTRY(tseg_qent) tqe_q;
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| 73 | int tqe_len; /* TCP segment data length */
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| 74 | struct tcphdr *tqe_th; /* a pointer to tcp header */
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| 75 | struct mbuf *tqe_m; /* mbuf contains packet */
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| 76 | };
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| 77 | LIST_HEAD(tsegqe_head, tseg_qent);
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| 78 |
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| 79 | /*
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| 80 | * Tcp control block, one per tcp; fields:
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| 81 | */
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| 82 | struct tcpcb
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| 83 | {
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| 84 | LIST_ENTRY(tcpcb) t_list;
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| 85 | struct tsegqe_head t_segq; /* segment reassembly queue */
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| 86 | int t_segqlen; /* segment reassembly queue length */
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| 87 | int16_t t_state; /* state of this connection */
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| 88 | int16_t t_timer[TCPT_NTIMERS]; /* tcp timers */
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| 89 | int16_t t_rxtshift; /* log(2) of rexmt exp. backoff */
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| 90 | int16_t t_rxtcur; /* current retransmit value */
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| 91 | int16_t t_dupacks; /* consecutive dup acks recd */
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| 92 | uint16_t t_maxseg; /* maximum segment size */
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| 93 | char t_force; /* 1 if forcing out a byte */
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| 94 | uint16_t t_flags;
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| 95 | #define TF_ACKNOW 0x0001 /* ack peer immediately */
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| 96 | #define TF_DELACK 0x0002 /* ack, but try to delay it */
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| 97 | #define TF_NODELAY 0x0004 /* don't delay packets to coalesce */
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| 98 | #define TF_NOOPT 0x0008 /* don't use tcp options */
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| 99 | #define TF_SENTFIN 0x0010 /* have sent FIN */
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| 100 | #define TF_REQ_SCALE 0x0020 /* have/will request window scaling */
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| 101 | #define TF_RCVD_SCALE 0x0040 /* other side has requested scaling */
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| 102 | #define TF_REQ_TSTMP 0x0080 /* have/will request timestamps */
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| 103 | #define TF_RCVD_TSTMP 0x0100 /* a timestamp was received in SYN */
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| 104 | #define TF_SACK_PERMIT 0x0200 /* other side said I could SACK */
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| 105 |
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| 106 | /* Make it static for now */
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| 107 | /* struct tcpiphdr *t_template; / * skeletal packet for transmit */
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| 108 | struct tcpiphdr t_template;
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| 109 |
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| 110 | struct socket *t_socket; /* back pointer to socket */
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| 111 | /*
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| 112 | * The following fields are used as in the protocol specification.
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| 113 | * See RFC783, Dec. 1981, page 21.
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| 114 | */
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| 115 | /* send sequence variables */
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| 116 | tcp_seq snd_una; /* send unacknowledged */
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| 117 | tcp_seq snd_nxt; /* send next */
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| 118 | tcp_seq snd_up; /* send urgent pointer */
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| 119 | tcp_seq snd_wl1; /* window update seg seq number */
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| 120 | tcp_seq snd_wl2; /* window update seg ack number */
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| 121 | tcp_seq iss; /* initial send sequence number */
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| 122 | uint32_t snd_wnd; /* send window */
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| 123 | /* receive sequence variables */
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| 124 | uint32_t rcv_wnd; /* receive window */
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| 125 | tcp_seq rcv_nxt; /* receive next */
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| 126 | tcp_seq rcv_up; /* receive urgent pointer */
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| 127 | tcp_seq irs; /* initial receive sequence number */
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| 128 | /*
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| 129 | * Additional variables for this implementation.
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| 130 | */
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| 131 | /* receive variables */
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| 132 | tcp_seq rcv_adv; /* advertised window */
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| 133 | /* retransmit variables */
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| 134 | tcp_seq snd_max; /* highest sequence number sent;
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| 135 | * used to recognize retransmits
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| 136 | */
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| 137 | /* congestion control (for slow start, source quench, retransmit after loss) */
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| 138 | uint32_t snd_cwnd; /* congestion-controlled window */
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| 139 | uint32_t snd_ssthresh; /* snd_cwnd size threshold for
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| 140 | * for slow start exponential to
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| 141 | * linear switch
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| 142 | */
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| 143 | /*
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| 144 | * transmit timing stuff. See below for scale of srtt and rttvar.
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| 145 | * "Variance" is actually smoothed difference.
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| 146 | */
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| 147 | int16_t t_idle; /* inactivity time */
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| 148 | int16_t t_rtt; /* round trip time */
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| 149 | tcp_seq t_rtseq; /* sequence number being timed */
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| 150 | int16_t t_srtt; /* smoothed round-trip time */
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| 151 | int16_t t_rttvar; /* variance in round-trip time */
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| 152 | uint16_t t_rttmin; /* minimum rtt allowed */
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| 153 | uint32_t max_sndwnd; /* largest window peer has offered */
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| 154 |
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| 155 | /* out-of-band data */
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| 156 | char t_oobflags; /* have some */
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| 157 | char t_iobc; /* input character */
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| 158 | #define TCPOOB_HAVEDATA 0x01
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| 159 | #define TCPOOB_HADDATA 0x02
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| 160 | short t_softerror; /* possible error not yet reported */
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| 161 |
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| 162 | /* RFC 1323 variables */
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| 163 | uint8_t snd_scale; /* window scaling for send window */
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| 164 | uint8_t rcv_scale; /* window scaling for recv window */
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| 165 | uint8_t request_r_scale; /* pending window scaling */
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| 166 | uint8_t requested_s_scale;
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| 167 | uint32_t ts_recent; /* timestamp echo data */
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| 168 | uint32_t ts_recent_age; /* when last updated */
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| 169 | tcp_seq last_ack_sent;
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| 170 | };
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| 171 |
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| 172 | LIST_HEAD(tcpcbhead, tcpcb);
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| 173 |
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| 174 | #define sototcpcb(so) ((so)->so_tcpcb)
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| 175 |
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| 176 | /*
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| 177 | * The smoothed round-trip time and estimated variance
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| 178 | * are stored as fixed point numbers scaled by the values below.
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| 179 | * For convenience, these scales are also used in smoothing the average
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| 180 | * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
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| 181 | * With these scales, srtt has 3 bits to the right of the binary point,
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| 182 | * and thus an "ALPHA" of 0.875. rttvar has 2 bits to the right of the
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| 183 | * binary point, and is smoothed with an ALPHA of 0.75.
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| 184 | */
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| 185 | #define TCP_RTT_SCALE 8 /* multiplier for srtt; 3 bits frac. */
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| 186 | #define TCP_RTT_SHIFT 3 /* shift for srtt; 3 bits frac. */
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| 187 | #define TCP_RTTVAR_SCALE 4 /* multiplier for rttvar; 2 bits */
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| 188 | #define TCP_RTTVAR_SHIFT 2 /* multiplier for rttvar; 2 bits */
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| 189 |
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| 190 | /*
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| 191 | * The initial retransmission should happen at rtt + 4 * rttvar.
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| 192 | * Because of the way we do the smoothing, srtt and rttvar
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| 193 | * will each average +1/2 tick of bias. When we compute
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| 194 | * the retransmit timer, we want 1/2 tick of rounding and
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| 195 | * 1 extra tick because of +-1/2 tick uncertainty in the
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| 196 | * firing of the timer. The bias will give us exactly the
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| 197 | * 1.5 tick we need. But, because the bias is
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| 198 | * statistical, we have to test that we don't drop below
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| 199 | * the minimum feasible timer (which is 2 ticks).
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| 200 | * This macro assumes that the value of TCP_RTTVAR_SCALE
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| 201 | * is the same as the multiplier for rttvar.
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| 202 | */
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| 203 | #define TCP_REXMTVAL(tp) \
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| 204 | (((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar)
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| 205 |
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| 206 | /*
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| 207 | * TCP statistics.
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| 208 | * Many of these should be kept per connection,
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| 209 | * but that's inconvenient at the moment.
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| 210 | */
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| 211 | struct tcpstat_t
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| 212 | {
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| 213 | u_long tcps_connattempt; /* connections initiated */
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| 214 | u_long tcps_accepts; /* connections accepted */
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| 215 | u_long tcps_connects; /* connections established */
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| 216 | u_long tcps_drops; /* connections dropped */
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| 217 | u_long tcps_conndrops; /* embryonic connections dropped */
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| 218 | u_long tcps_closed; /* conn. closed (includes drops) */
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| 219 | u_long tcps_segstimed; /* segs where we tried to get rtt */
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| 220 | u_long tcps_rttupdated; /* times we succeeded */
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| 221 | u_long tcps_delack; /* delayed acks sent */
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| 222 | u_long tcps_timeoutdrop; /* conn. dropped in rxmt timeout */
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| 223 | u_long tcps_rexmttimeo; /* retransmit timeouts */
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| 224 | u_long tcps_persisttimeo; /* persist timeouts */
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| 225 | u_long tcps_keeptimeo; /* keepalive timeouts */
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| 226 | u_long tcps_keepprobe; /* keepalive probes sent */
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| 227 | u_long tcps_keepdrops; /* connections dropped in keepalive */
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| 228 |
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| 229 | u_long tcps_sndtotal; /* total packets sent */
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| 230 | u_long tcps_sndpack; /* data packets sent */
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| 231 | u_long tcps_sndbyte; /* data bytes sent */
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| 232 | u_long tcps_sndrexmitpack; /* data packets retransmitted */
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| 233 | u_long tcps_sndrexmitbyte; /* data bytes retransmitted */
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| 234 | u_long tcps_sndacks; /* ack-only packets sent */
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| 235 | u_long tcps_sndprobe; /* window probes sent */
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| 236 | u_long tcps_sndurg; /* packets sent with URG only */
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| 237 | u_long tcps_sndwinup; /* window update-only packets sent */
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| 238 | u_long tcps_sndctrl; /* control (SYN|FIN|RST) packets sent */
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| 239 |
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| 240 | u_long tcps_rcvtotal; /* total packets received */
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| 241 | u_long tcps_rcvpack; /* packets received in sequence */
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| 242 | u_long tcps_rcvbyte; /* bytes received in sequence */
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| 243 | u_long tcps_rcvbadsum; /* packets received with ccksum errs */
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| 244 | u_long tcps_rcvbadoff; /* packets received with bad offset */
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| 245 | /* u_long tcps_rcvshort; */ /* packets received too short */
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| 246 | u_long tcps_rcvduppack; /* duplicate-only packets received */
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| 247 | u_long tcps_rcvdupbyte; /* duplicate-only bytes received */
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| 248 | u_long tcps_rcvpartduppack; /* packets with some duplicate data */
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| 249 | u_long tcps_rcvpartdupbyte; /* dup. bytes in part-dup. packets */
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| 250 | u_long tcps_rcvoopack; /* out-of-order packets received */
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| 251 | u_long tcps_rcvoobyte; /* out-of-order bytes received */
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| 252 | u_long tcps_rcvpackafterwin; /* packets with data after window */
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| 253 | u_long tcps_rcvbyteafterwin; /* bytes rcvd after window */
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| 254 | u_long tcps_rcvafterclose; /* packets rcvd after "close" */
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| 255 | u_long tcps_rcvwinprobe; /* rcvd window probe packets */
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| 256 | u_long tcps_rcvdupack; /* rcvd duplicate acks */
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| 257 | u_long tcps_rcvacktoomuch; /* rcvd acks for unsent data */
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| 258 | u_long tcps_rcvackpack; /* rcvd ack packets */
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| 259 | u_long tcps_rcvackbyte; /* bytes acked by rcvd acks */
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| 260 | u_long tcps_rcvwinupd; /* rcvd window update packets */
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| 261 | /* u_long tcps_pawsdrop; */ /* segments dropped due to PAWS */
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| 262 | u_long tcps_predack; /* times hdr predict ok for acks */
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| 263 | u_long tcps_preddat; /* times hdr predict ok for data pkts */
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| 264 | u_long tcps_socachemiss; /* tcp_last_so misses */
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| 265 | u_long tcps_didnuttin; /* Times tcp_output didn't do anything XXX */
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| 266 | u_long tcps_rcvmemdrop;
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| 267 | };
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| 268 |
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| 269 | #endif
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