/* $Id: tcp_var.h 98103 2023-01-17 14:15:46Z vboxsync $ */ /** @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 . * * 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