bellard | f0cbd3e | 2004-04-22 00:10:48 +0000 | [diff] [blame] | 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. |
aliguori | 2f5f899 | 2009-01-26 19:37:41 +0000 | [diff] [blame] | 13 | * 3. Neither the name of the University nor the names of its contributors |
bellard | f0cbd3e | 2004-04-22 00:10:48 +0000 | [diff] [blame] | 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 | |
bellard | f0cbd3e | 2004-04-22 00:10:48 +0000 | [diff] [blame] | 39 | /* |
| 40 | * Tcp control block, one per tcp; fields: |
| 41 | */ |
| 42 | struct tcpcb { |
blueswir1 | 429d0a3 | 2009-01-13 19:48:42 +0000 | [diff] [blame] | 43 | struct tcpiphdr *seg_next; /* sequencing queue */ |
| 44 | struct tcpiphdr *seg_prev; |
bellard | f0cbd3e | 2004-04-22 00:10:48 +0000 | [diff] [blame] | 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 | |
Jan Kiszka | 0d62c4c | 2009-06-24 14:42:29 +0200 | [diff] [blame] | 64 | struct tcpiphdr t_template; /* static skeletal packet for xmit */ |
bellard | f0cbd3e | 2004-04-22 00:10:48 +0000 | [diff] [blame] | 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 */ |
Stefan Weil | b6dce92 | 2010-07-22 22:15:23 +0200 | [diff] [blame] | 78 | uint32_t snd_wnd; /* send window */ |
bellard | f0cbd3e | 2004-04-22 00:10:48 +0000 | [diff] [blame] | 79 | /* receive sequence variables */ |
Stefan Weil | b6dce92 | 2010-07-22 22:15:23 +0200 | [diff] [blame] | 80 | uint32_t rcv_wnd; /* receive window */ |
bellard | f0cbd3e | 2004-04-22 00:10:48 +0000 | [diff] [blame] | 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) */ |
Stefan Weil | b6dce92 | 2010-07-22 22:15:23 +0200 | [diff] [blame] | 94 | uint32_t snd_cwnd; /* congestion-controlled window */ |
| 95 | uint32_t snd_ssthresh; /* snd_cwnd size threshold for |
bellard | f0cbd3e | 2004-04-22 00:10:48 +0000 | [diff] [blame] | 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 */ |
Stefan Weil | b6dce92 | 2010-07-22 22:15:23 +0200 | [diff] [blame] | 109 | uint32_t max_sndwnd; /* largest window peer has offered */ |
bellard | f0cbd3e | 2004-04-22 00:10:48 +0000 | [diff] [blame] | 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; |
Stefan Weil | b6dce92 | 2010-07-22 22:15:23 +0200 | [diff] [blame] | 123 | uint32_t ts_recent; /* timestamp echo data */ |
| 124 | uint32_t ts_recent_age; /* when last updated */ |
bellard | f0cbd3e | 2004-04-22 00:10:48 +0000 | [diff] [blame] | 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 | |
bellard | f0cbd3e | 2004-04-22 00:10:48 +0000 | [diff] [blame] | 161 | #endif |