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- /*-
- * SPDX-License-Identifier: BSD-3-Clause
- *
- * 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.
- * 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_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 ( 1*hz) /* assumed RTO if no info */
- #define TCPTV_PERSMIN ( 5*hz) /* minimum persist interval */
- #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/25 ) /* 40ms timeout */
- /*
- * If we exceed this number of retransmits for a single segment, we'll consider
- * the current srtt measurement no longer valid and will recalculate from
- * scratch starting with the next ACK.
- */
- #define TCP_RTT_INVALIDATE (TCP_MAXRXTSHIFT / 4)
- #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 */
- uint32_t tt_flags; /* Timers flags */
- uint32_t tt_draincnt; /* Count being drained */
- };
- /*
- * Flags for the tt_flags field.
- */
- #define TT_DELACK 0x0001
- #define TT_REXMT 0x0002
- #define TT_PERSIST 0x0004
- #define TT_KEEP 0x0008
- #define TT_2MSL 0x0010
- #define TT_MASK (TT_DELACK|TT_REXMT|TT_PERSIST|TT_KEEP|TT_2MSL)
- /*
- * Suspend flags - used when suspending a timer
- * from ever running again.
- */
- #define TT_DELACK_SUS 0x0100
- #define TT_REXMT_SUS 0x0200
- #define TT_PERSIST_SUS 0x0400
- #define TT_KEEP_SUS 0x0800
- #define TT_2MSL_SUS 0x1000
- #define TT_STOPPED 0x00010000
- #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_persmin; /* minimum persist interval */
- extern int tcp_persmax; /* maximum persist interval */
- 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_initial;
- 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_totbackoff;
- extern int tcp_rexmit_drop_options;
- extern int tcp_finwait2_timeout;
- extern int tcp_fast_finwait2_recycle;
- VNET_DECLARE(int, tcp_always_keepalive);
- #define V_tcp_always_keepalive VNET(tcp_always_keepalive)
- VNET_DECLARE(int, tcp_pmtud_blackhole_detect);
- #define V_tcp_pmtud_blackhole_detect VNET(tcp_pmtud_blackhole_detect)
- VNET_DECLARE(int, tcp_pmtud_blackhole_mss);
- #define V_tcp_pmtud_blackhole_mss VNET(tcp_pmtud_blackhole_mss)
- VNET_DECLARE(int, tcp_v6pmtud_blackhole_mss);
- #define V_tcp_v6pmtud_blackhole_mss VNET(tcp_v6pmtud_blackhole_mss)
- void tcp_inpinfo_lock_del(struct inpcb *inp, struct tcpcb *tp);
- void tcp_timer_init(void);
- void tcp_timer_2msl(void *xtp);
- void tcp_timer_discard(void *);
- 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 /* _KERNEL */
- #endif /* !_NETINET_TCP_TIMER_H_ */
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