Annotation of qemu/slirp/tcp_timer.h, revision 1.1.1.4

1.1       root        1: /*
                      2:  * Copyright (c) 1982, 1986, 1993
                      3:  *     The Regents of the University of California.  All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms, with or without
                      6:  * modification, are permitted provided that the following conditions
                      7:  * are met:
                      8:  * 1. Redistributions of source code must retain the above copyright
                      9:  *    notice, this list of conditions and the following disclaimer.
                     10:  * 2. Redistributions in binary form must reproduce the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer in the
                     12:  *    documentation and/or other materials provided with the distribution.
1.1.1.3   root       13:  * 3. Neither the name of the University nor the names of its contributors
1.1       root       14:  *    may be used to endorse or promote products derived from this software
                     15:  *    without specific prior written permission.
                     16:  *
                     17:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     18:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     19:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     20:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     21:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     22:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     23:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     24:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     25:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     26:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     27:  * SUCH DAMAGE.
                     28:  *
                     29:  *     @(#)tcp_timer.h 8.1 (Berkeley) 6/10/93
                     30:  * tcp_timer.h,v 1.4 1994/08/21 05:27:38 paul Exp
                     31:  */
                     32: 
                     33: #ifndef _TCP_TIMER_H_
                     34: #define _TCP_TIMER_H_
                     35: 
                     36: /*
                     37:  * Definitions of the TCP timers.  These timers are counted
                     38:  * down PR_SLOWHZ times a second.
                     39:  */
                     40: #define        TCPT_NTIMERS    4
                     41: 
                     42: #define        TCPT_REXMT      0               /* retransmit */
                     43: #define        TCPT_PERSIST    1               /* retransmit persistence */
                     44: #define        TCPT_KEEP       2               /* keep alive */
                     45: #define        TCPT_2MSL       3               /* 2*msl quiet time timer */
                     46: 
                     47: /*
                     48:  * The TCPT_REXMT timer is used to force retransmissions.
                     49:  * The TCP has the TCPT_REXMT timer set whenever segments
                     50:  * have been sent for which ACKs are expected but not yet
                     51:  * received.  If an ACK is received which advances tp->snd_una,
                     52:  * then the retransmit timer is cleared (if there are no more
                     53:  * outstanding segments) or reset to the base value (if there
                     54:  * are more ACKs expected).  Whenever the retransmit timer goes off,
                     55:  * we retransmit one unacknowledged segment, and do a backoff
                     56:  * on the retransmit timer.
                     57:  *
                     58:  * The TCPT_PERSIST timer is used to keep window size information
                     59:  * flowing even if the window goes shut.  If all previous transmissions
                     60:  * have been acknowledged (so that there are no retransmissions in progress),
                     61:  * and the window is too small to bother sending anything, then we start
                     62:  * the TCPT_PERSIST timer.  When it expires, if the window is nonzero,
                     63:  * we go to transmit state.  Otherwise, at intervals send a single byte
                     64:  * into the peer's window to force him to update our window information.
                     65:  * We do this at most as often as TCPT_PERSMIN time intervals,
                     66:  * but no more frequently than the current estimate of round-trip
                     67:  * packet time.  The TCPT_PERSIST timer is cleared whenever we receive
                     68:  * a window update from the peer.
                     69:  *
                     70:  * The TCPT_KEEP timer is used to keep connections alive.  If an
                     71:  * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time,
                     72:  * but not yet established, then we drop the connection.  Once the connection
                     73:  * is established, if the connection is idle for TCPTV_KEEP_IDLE time
                     74:  * (and keepalives have been enabled on the socket), we begin to probe
                     75:  * the connection.  We force the peer to send us a segment by sending:
                     76:  *     <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK>
                     77:  * This segment is (deliberately) outside the window, and should elicit
                     78:  * an ack segment in response from the peer.  If, despite the TCPT_KEEP
                     79:  * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE
                     80:  * amount of time probing, then we drop the connection.
                     81:  */
                     82: 
                     83: /*
                     84:  * Time constants.
                     85:  */
                     86: #define TCPTV_MSL       ( 5*PR_SLOWHZ)          /* max seg lifetime (hah!) */
                     87: 
                     88: #define        TCPTV_SRTTBASE  0                       /* base roundtrip time;
                     89:                                                   if 0, no idea yet */
                     90: #define        TCPTV_SRTTDFLT  (  3*PR_SLOWHZ)         /* assumed RTT if no info */
                     91: 
                     92: #define        TCPTV_PERSMIN   (  5*PR_SLOWHZ)         /* retransmit persistence */
                     93: #define        TCPTV_PERSMAX   ( 60*PR_SLOWHZ)         /* maximum persist interval */
                     94: 
                     95: #define        TCPTV_KEEP_INIT ( 75*PR_SLOWHZ)         /* initial connect keep alive */
                     96: #define        TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ)      /* dflt time before probing */
                     97: #define        TCPTV_KEEPINTVL ( 75*PR_SLOWHZ)         /* default probe interval */
                     98: #define        TCPTV_KEEPCNT   8                       /* max probes before drop */
                     99: 
                    100: #define        TCPTV_MIN       (  1*PR_SLOWHZ)         /* minimum allowable value */
                    101: #define TCPTV_REXMTMAX  ( 12*PR_SLOWHZ)                /* max allowable REXMT value */
                    102: 
                    103: #define        TCP_LINGERTIME  120                     /* linger at most 2 minutes */
                    104: 
                    105: #define TCP_MAXRXTSHIFT 12                      /* maximum retransmits */
                    106: 
                    107: 
                    108: /*
                    109:  * Force a time value to be in a certain range.
                    110:  */
                    111: #define        TCPT_RANGESET(tv, value, tvmin, tvmax) { \
                    112:        (tv) = (value); \
                    113:        if ((tv) < (tvmin)) \
                    114:                (tv) = (tvmin); \
                    115:        else if ((tv) > (tvmax)) \
                    116:                (tv) = (tvmax); \
                    117: }
                    118: 
1.1.1.2   root      119: extern const int tcp_backoff[];
1.1       root      120: 
                    121: struct tcpcb;
                    122: 
1.1.1.4 ! root      123: void tcp_fasttimo(Slirp *);
        !           124: void tcp_slowtimo(Slirp *);
        !           125: void tcp_canceltimers(struct tcpcb *);
1.1       root      126: 
                    127: #endif

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