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Diffstat (limited to 'slirp/src/tcp_var.h')
| -rw-r--r-- | slirp/src/tcp_var.h | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/slirp/src/tcp_var.h b/slirp/src/tcp_var.h new file mode 100644 index 0000000000..27ef1a51cb --- /dev/null +++ b/slirp/src/tcp_var.h @@ -0,0 +1,161 @@ +/* + * 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 */ + uint16_t t_maxseg; /* maximum segment size */ + uint8_t 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 */ + + 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 */ + uint16_t t_rttmin; /* minimum rtt allowed */ + uint32_t max_sndwnd; /* largest window peer has offered */ + +/* out-of-band data */ + uint8_t t_oobflags; /* have some */ + uint8_t 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; + +}; + +#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 |