| /*- |
| * Copyright (c) 1982, 1986, 1993 |
| * 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. |
| * 4. 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_timer.h 8.1 (Berkeley) 6/10/93 |
| * $FreeBSD$ |
| */ |
| |
| #ifndef _BSD_NETINET_TCP_TIMER_H_ |
| #define _BSD_NETINET_TCP_TIMER_H_ |
| |
| /* |
| * The TCPT_REXMT timer is used to force retransmissions. |
| * The TCP has the TCPT_REXMT timer set whenever segments |
| * have been sent for which ACKs are expected but not yet |
| * received. If an ACK is received which advances tp->snd_una, |
| * then the retransmit timer is cleared (if there are no more |
| * outstanding segments) or reset to the base value (if there |
| * are more ACKs expected). Whenever the retransmit timer goes off, |
| * we retransmit one unacknowledged segment, and do a backoff |
| * on the retransmit timer. |
| * |
| * The TCPT_PERSIST timer is used to keep window size information |
| * flowing even if the window goes shut. If all previous transmissions |
| * have been acknowledged (so that there are no retransmissions in progress), |
| * and the window is too small to bother sending anything, then we start |
| * the TCPT_PERSIST timer. When it expires, if the window is nonzero, |
| * we go to transmit state. Otherwise, at intervals send a single byte |
| * into the peer's window to force him to update our window information. |
| * We do this at most as often as TCPT_PERSMIN time intervals, |
| * but no more frequently than the current estimate of round-trip |
| * packet time. The TCPT_PERSIST timer is cleared whenever we receive |
| * a window update from the peer. |
| * |
| * The TCPT_KEEP timer is used to keep connections alive. If an |
| * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time, |
| * but not yet established, then we drop the connection. Once the connection |
| * is established, if the connection is idle for TCPTV_KEEP_IDLE time |
| * (and keepalives have been enabled on the socket), we begin to probe |
| * the connection. We force the peer to send us a segment by sending: |
| * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK> |
| * This segment is (deliberately) outside the window, and should elicit |
| * an ack segment in response from the peer. If, despite the TCPT_KEEP |
| * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE |
| * amount of time probing, then we drop the connection. |
| */ |
| |
| /* |
| * Time constants. |
| */ |
| #define TCPTV_MSL ( 30*bsd_hz) /* max seg lifetime (hah!) */ |
| #define TCPTV_SRTTBASE 0 /* base roundtrip time; |
| if 0, no idea yet */ |
| #define TCPTV_RTOBASE ( 3*bsd_hz) /* assumed RTO if no info */ |
| #define TCPTV_SRTTDFLT ( 3*bsd_hz) /* assumed RTT if no info */ |
| |
| #define TCPTV_PERSMIN ( 5*bsd_hz) /* retransmit persistence */ |
| #define TCPTV_PERSMAX ( 60*bsd_hz) /* maximum persist interval */ |
| |
| #define TCPTV_KEEP_INIT ( 75*bsd_hz) /* initial connect keepalive */ |
| #define TCPTV_KEEP_IDLE (120*60*bsd_hz) /* dflt time before probing */ |
| #define TCPTV_KEEPINTVL ( 75*bsd_hz) /* default probe interval */ |
| #define TCPTV_KEEPCNT 8 /* max probes before drop */ |
| |
| #define TCPTV_INFLIGHT_RTTTHRESH (10*bsd_hz/1000) /* below which inflight |
| disengages, in msec */ |
| |
| #define TCPTV_FINWAIT2_TIMEOUT (60*bsd_hz) /* FIN_WAIT_2 timeout if no receiver */ |
| |
| /* |
| * Minimum retransmit timer is 3 ticks, for algorithmic stability. |
| * TCPT_RANGESET() will add another TCPTV_CPU_VAR to deal with |
| * the expected worst-case processing variances by the kernels |
| * representing the end points. Such variances do not always show |
| * up in the srtt because the timestamp is often calculated at |
| * the interface rather then at the TCP layer. This value is |
| * typically 50ms. However, it is also possible that delayed |
| * acks (typically 100ms) could create issues so we set the slop |
| * to 200ms to try to cover it. Note that, properly speaking, |
| * delayed-acks should not create a major issue for interactive |
| * environments which 'P'ush the last segment, at least as |
| * long as implementations do the required 'at least one ack |
| * for every two packets' for the non-interactive streaming case. |
| * (maybe the RTO calculation should use 2*RTT instead of RTT |
| * to handle the ack-every-other-packet case). |
| * |
| * The prior minimum of 1*hz (1 second) badly breaks throughput on any |
| * networks faster then a modem that has minor (e.g. 1%) packet loss. |
| */ |
| #define TCPTV_MIN ( bsd_hz/33 ) /* minimum allowable value */ |
| #define TCPTV_CPU_VAR ( bsd_hz/5 ) /* cpu variance allowed (200ms) */ |
| #define TCPTV_REXMTMAX ( 64*bsd_hz) /* max allowable REXMT value */ |
| |
| #define TCPTV_TWTRUNC 8 /* RTO factor to truncate TW */ |
| |
| #define TCP_LINGERTIME 120 /* linger at most 2 minutes */ |
| |
| #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */ |
| |
| #define TCPTV_DELACK (bsd_hz / PR_FASTHZ / 2) /* 100ms timeout */ |
| |
| #ifdef TCPTIMERS |
| static const char *tcptimers[] = |
| { "REXMT", "PERSIST", "KEEP", "2MSL" }; |
| #endif |
| |
| /* |
| * Force a time value to be in a certain range. |
| */ |
| #define TCPT_RANGESET(tv, value, tvmin, tvmax) do { \ |
| (tv) = (value) + tcp_rexmit_slop; \ |
| if ((u_long)(tv) < (u_long)(tvmin)) \ |
| (tv) = (tvmin); \ |
| if ((u_long)(tv) > (u_long)(tvmax)) \ |
| (tv) = (tvmax); \ |
| } while(0) |
| |
| #ifdef _FREEBSD_KERNEL |
| |
| struct tcp_timer { |
| struct callout tt_rexmt; /* retransmit timer */ |
| struct callout tt_persist; /* retransmit persistence */ |
| struct callout tt_keep; /* keepalive */ |
| struct callout tt_2msl; /* 2*msl TIME_WAIT timer */ |
| struct callout tt_delack; /* delayed ACK timer */ |
| }; |
| #define TT_DELACK 0x01 |
| #define TT_REXMT 0x02 |
| #define TT_PERSIST 0x04 |
| #define TT_KEEP 0x08 |
| #define TT_2MSL 0x10 |
| |
| extern int tcp_keepinit; /* time to establish connection */ |
| extern int tcp_keepidle; /* time before keepalive probes begin */ |
| extern int tcp_keepintvl; /* time between keepalive probes */ |
| extern int tcp_maxidle; /* time to drop after starting probes */ |
| extern int tcp_delacktime; /* time before sending a delayed ACK */ |
| extern int tcp_maxpersistidle; |
| extern int tcp_rexmit_min; |
| extern int tcp_rexmit_slop; |
| extern int tcp_msl; |
| extern int tcp_ttl; /* time to live for TCP segs */ |
| extern int tcp_backoff[]; |
| |
| extern int tcp_finwait2_timeout; |
| extern int tcp_fast_finwait2_recycle; |
| |
| void tcp_timer_init(void); |
| void tcp_timer_2msl(void *xtp); |
| struct tcptw * |
| tcp_tw_2msl_scan(int _reuse); /* XXX temporary */ |
| void tcp_timer_keep(void *xtp); |
| void tcp_timer_persist(void *xtp); |
| void tcp_timer_rexmt(void *xtp); |
| void tcp_timer_delack(void *xtp); |
| |
| #endif /* _FREEBSD_KERNEL */ |
| |
| #endif /* !_BSD_NETINET_TCP_TIMER_H_ */ |
