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Diffstat (limited to 'cpukit/libnetworking/netinet/tcp_timer.h')
| -rw-r--r-- | cpukit/libnetworking/netinet/tcp_timer.h | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/cpukit/libnetworking/netinet/tcp_timer.h b/cpukit/libnetworking/netinet/tcp_timer.h new file mode 100644 index 0000000000..4bbbb712b6 --- /dev/null +++ b/cpukit/libnetworking/netinet/tcp_timer.h @@ -0,0 +1,133 @@ +/* + * 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: src/sys/netinet/tcp_timer.h,v 1.26 2004/08/16 18:32:07 rwatson 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); \ +} + +#ifdef _KERNEL +extern int tcp_keepinit; /* time to establish connection */ +extern int tcp_keepidle; /* time before keepalive probes begin */ +extern int tcp_maxidle; /* time to drop after starting probes */ +extern int tcp_ttl; /* time to live for TCP segs */ +extern int tcp_backoff[]; +#endif + +#endif |