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/*!\file netinet/tcp_time.h |
* TCP timer definitions. |
*/ |
|
/* |
* 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. All advertising materials mentioning features or use of this software |
* must display the following acknowledgement: |
* This product includes software developed by the University of |
* California, Berkeley and its contributors. |
* 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 |
* $Id: tcp_timer.h,v 1.10 1996/09/13 23:51:43 pst Exp $ |
*/ |
|
#ifndef __NETINET_TCP_TIMER_H |
#define __NETINET_TCP_TIMER_H |
|
/* |
* Definitions of the TCP timers. These timers are counted |
* down PR_SLOWHZ times a second. |
*/ |
#define TCPT_NTIMERS 4 |
|
#define TCPT_REXMT 0 /* retransmit */ |
#define TCPT_PERSIST 1 /* retransmit persistence */ |
#define TCPT_KEEP 2 /* keep alive */ |
#define TCPT_2MSL 3 /* 2*msl quiet time timer */ |
|
/* |
* 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*PR_SLOWHZ) /* max seg lifetime (hah!) */ |
#define TCPTV_SRTTBASE 0 /* base roundtrip time; |
if 0, no idea yet */ |
#define TCPTV_RTOBASE ( 3*PR_SLOWHZ) /* assumed RTO if no info */ |
#define TCPTV_SRTTDFLT ( 3*PR_SLOWHZ) /* assumed RTT if no info */ |
|
#define TCPTV_PERSMIN ( 5*PR_SLOWHZ) /* retransmit persistence */ |
#define TCPTV_PERSMAX ( 60*PR_SLOWHZ) /* maximum persist interval */ |
|
#define TCPTV_KEEP_INIT ( 75*PR_SLOWHZ) /* initial connect keep alive */ |
#define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ) /* dflt time before probing */ |
#define TCPTV_KEEPINTVL ( 75*PR_SLOWHZ) /* default probe interval */ |
#define TCPTV_KEEPCNT 8 /* max probes before drop */ |
|
#define TCPTV_MIN ( 1*PR_SLOWHZ) /* minimum allowable value */ |
#define TCPTV_REXMTMAX ( 64*PR_SLOWHZ) /* 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 */ |
|
#ifdef TCPTIMERS |
static char *tcptimers[] = |
{ "REXMT", "PERSIST", "KEEP", "2MSL" }; |
#endif |
|
/* |
* Force a time value to be in a certain range. |
*/ |
#define TCPT_RANGESET(tv, value, tvmin, tvmax) { \ |
(tv) = (value); \ |
if ((u_long)(tv) < (u_long)(tvmin)) \ |
(tv) = (tvmin); \ |
else if ((u_long)(tv) > (u_long)(tvmax)) \ |
(tv) = (tvmax); \ |
} |
|
#endif |