| /* | |
| * 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 "tcpip.h" | |
| #include "tcp_timer.h" | |
| /* | |
| * Tcp control block, one per tcp; fields: | |
| */ | |
| struct tcpcb { | |
| struct tcpiphdr *seg_next; /* sequencing queue */ | |
| struct tcpiphdr *seg_prev; | |
| short t_state; /* state of this connection */ | |
| short t_timer[TCPT_NTIMERS]; /* tcp timers */ | |
| short t_rxtshift; /* log(2) of rexmt exp. backoff */ | |
| short t_rxtcur; /* current retransmit value */ | |
| short t_dupacks; /* consecutive dup acks recd */ | |
| u_short t_maxseg; /* maximum segment size */ | |
| char t_force; /* 1 if forcing out a byte */ | |
| u_short 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 */ | |
| struct tcpiphdr t_template; /* static skeletal packet for xmit */ | |
| 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. | |
| */ | |
| short t_idle; /* inactivity time */ | |
| short t_rtt; /* round trip time */ | |
| tcp_seq t_rtseq; /* sequence number being timed */ | |
| short t_srtt; /* smoothed round-trip time */ | |
| short t_rttvar; /* variance in round-trip time */ | |
| u_short 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 */ | |
| u_char snd_scale; /* window scaling for send window */ | |
| u_char rcv_scale; /* window scaling for recv window */ | |
| u_char request_r_scale; /* pending window scaling */ | |
| u_char requested_s_scale; | |
| uint32_t ts_recent; /* timestamp echo data */ | |
| uint32_t ts_recent_age; /* when last updated */ | |
| tcp_seq last_ack_sent; | |
| }; | |
| #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) | |
| #endif |