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Diffstat (limited to 'sys/netinet/tcp_timer.h')
| -rw-r--r-- | sys/netinet/tcp_timer.h | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/sys/netinet/tcp_timer.h b/sys/netinet/tcp_timer.h new file mode 100644 index 0000000..3115fb3 --- /dev/null +++ b/sys/netinet/tcp_timer.h @@ -0,0 +1,191 @@ +/*- + * 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 _NETINET_TCP_TIMER_H_ +#define _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*hz) /* max seg lifetime (hah!) */ +#define TCPTV_SRTTBASE 0 /* base roundtrip time; + if 0, no idea yet */ +#define TCPTV_RTOBASE ( 3*hz) /* assumed RTO if no info */ +#define TCPTV_SRTTDFLT ( 3*hz) /* assumed RTT if no info */ + +#define TCPTV_PERSMIN ( 5*hz) /* retransmit persistence */ +#define TCPTV_PERSMAX ( 60*hz) /* maximum persist interval */ + +#define TCPTV_KEEP_INIT ( 75*hz) /* initial connect keepalive */ +#define TCPTV_KEEP_IDLE (120*60*hz) /* dflt time before probing */ +#define TCPTV_KEEPINTVL ( 75*hz) /* default probe interval */ +#define TCPTV_KEEPCNT 8 /* max probes before drop */ + +#define TCPTV_FINWAIT2_TIMEOUT (60*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 ( hz/33 ) /* minimum allowable value */ +#define TCPTV_CPU_VAR ( hz/5 ) /* cpu variance allowed (200ms) */ +#define TCPTV_REXMTMAX ( 64*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 ( hz/10 ) /* 100ms timeout */ + +#ifdef TCPTIMERS +static const char *tcptimers[] = + { "REXMT", "PERSIST", "KEEP", "2MSL", "DELACK" }; +#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 _KERNEL + +struct xtcp_timer; + +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 + +#define TP_KEEPINIT(tp) ((tp)->t_keepinit ? (tp)->t_keepinit : tcp_keepinit) +#define TP_KEEPIDLE(tp) ((tp)->t_keepidle ? (tp)->t_keepidle : tcp_keepidle) +#define TP_KEEPINTVL(tp) ((tp)->t_keepintvl ? (tp)->t_keepintvl : tcp_keepintvl) +#define TP_KEEPCNT(tp) ((tp)->t_keepcnt ? (tp)->t_keepcnt : tcp_keepcnt) +#define TP_MAXIDLE(tp) (TP_KEEPCNT(tp) * TP_KEEPINTVL(tp)) + +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_keepcnt; /* number of keepalives */ +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_syn_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); +void tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer, + struct xtcp_timer *xtimer); + +#endif /* _KERNEL */ + +#endif /* !_NETINET_TCP_TIMER_H_ */ |
