1*0Sstevel@tonic-gate /* 2*0Sstevel@tonic-gate * Copyright (c) 1982, 1986 Regents of the University of California. 3*0Sstevel@tonic-gate * All rights reserved. 4*0Sstevel@tonic-gate * 5*0Sstevel@tonic-gate * Redistribution and use in source and binary forms are permitted 6*0Sstevel@tonic-gate * provided that the above copyright notice and this paragraph are 7*0Sstevel@tonic-gate * duplicated in all such forms and that any documentation, 8*0Sstevel@tonic-gate * advertising materials, and other materials related to such 9*0Sstevel@tonic-gate * distribution and use acknowledge that the software was developed 10*0Sstevel@tonic-gate * by the University of California, Berkeley. The name of the 11*0Sstevel@tonic-gate * University may not be used to endorse or promote products derived 12*0Sstevel@tonic-gate * from this software without specific prior written permission. 13*0Sstevel@tonic-gate */ 14*0Sstevel@tonic-gate 15*0Sstevel@tonic-gate /* 16*0Sstevel@tonic-gate * Definitions of the TCP timers. These timers are counted 17*0Sstevel@tonic-gate * down PR_SLOWHZ times a second. 18*0Sstevel@tonic-gate */ 19*0Sstevel@tonic-gate 20*0Sstevel@tonic-gate #ifndef _NETINET_TCP_TIMER_H 21*0Sstevel@tonic-gate #define _NETINET_TCP_TIMER_H 22*0Sstevel@tonic-gate 23*0Sstevel@tonic-gate #pragma ident "%Z%%M% %I% %E% SMI" 24*0Sstevel@tonic-gate /* tcp_timer.h 1.13 89/06/16 SMI; from UCB 7.6 6/29/88 */ 25*0Sstevel@tonic-gate 26*0Sstevel@tonic-gate #ifdef __cplusplus 27*0Sstevel@tonic-gate extern "C" { 28*0Sstevel@tonic-gate #endif 29*0Sstevel@tonic-gate 30*0Sstevel@tonic-gate #define TCPT_NTIMERS 4 31*0Sstevel@tonic-gate 32*0Sstevel@tonic-gate #define TCPT_REXMT 0 /* retransmit */ 33*0Sstevel@tonic-gate #define TCPT_PERSIST 1 /* retransmit persistance */ 34*0Sstevel@tonic-gate #define TCPT_KEEP 2 /* keep alive */ 35*0Sstevel@tonic-gate #define TCPT_2MSL 3 /* 2*msl quiet time timer */ 36*0Sstevel@tonic-gate 37*0Sstevel@tonic-gate /* 38*0Sstevel@tonic-gate * The TCPT_REXMT timer is used to force retransmissions. 39*0Sstevel@tonic-gate * The TCP has the TCPT_REXMT timer set whenever segments 40*0Sstevel@tonic-gate * have been sent for which ACKs are expected but not yet 41*0Sstevel@tonic-gate * received. If an ACK is received which advances tp->snd_una, 42*0Sstevel@tonic-gate * then the retransmit timer is cleared (if there are no more 43*0Sstevel@tonic-gate * outstanding segments) or reset to the base value (if there 44*0Sstevel@tonic-gate * are more ACKs expected). Whenever the retransmit timer goes off, 45*0Sstevel@tonic-gate * we retransmit one unacknowledged segment, and do a backoff 46*0Sstevel@tonic-gate * on the retransmit timer. 47*0Sstevel@tonic-gate * 48*0Sstevel@tonic-gate * The TCPT_PERSIST timer is used to keep window size information 49*0Sstevel@tonic-gate * flowing even if the window goes shut. If all previous transmissions 50*0Sstevel@tonic-gate * have been acknowledged (so that there are no retransmissions in progress), 51*0Sstevel@tonic-gate * and the window is too small to bother sending anything, then we start 52*0Sstevel@tonic-gate * the TCPT_PERSIST timer. When it expires, if the window is nonzero, 53*0Sstevel@tonic-gate * we go to transmit state. Otherwise, at intervals send a single byte 54*0Sstevel@tonic-gate * into the peer's window to force him to update our window information. 55*0Sstevel@tonic-gate * We do this at most as often as TCPT_PERSMIN time intervals, 56*0Sstevel@tonic-gate * but no more frequently than the current estimate of round-trip 57*0Sstevel@tonic-gate * packet time. The TCPT_PERSIST timer is cleared whenever we receive 58*0Sstevel@tonic-gate * a window update from the peer. 59*0Sstevel@tonic-gate * 60*0Sstevel@tonic-gate * The TCPT_KEEP timer is used to keep connections alive. If a 61*0Sstevel@tonic-gate * connection is idle (no segments received) for TCPTV_KEEP_INIT amount of time, 62*0Sstevel@tonic-gate * but not yet established, then we drop the connection. Once the connection 63*0Sstevel@tonic-gate * is established, if the connection is idle for TCPTV_KEEP_IDLE time 64*0Sstevel@tonic-gate * (and keepalives have been enabled on the socket), we begin to probe 65*0Sstevel@tonic-gate * the connection. We force the peer to send us a segment by sending: 66*0Sstevel@tonic-gate * <SEQ=SND.UNA-1><ACK=RCV.NXT><CTL=ACK> 67*0Sstevel@tonic-gate * This segment is (deliberately) outside the window, and should elicit 68*0Sstevel@tonic-gate * an ack segment in response from the peer. If, despite the TCPT_KEEP 69*0Sstevel@tonic-gate * initiated segments we cannot elicit a response from a peer in TCPT_MAXIDLE 70*0Sstevel@tonic-gate * amount of time probing, then we drop the connection. 71*0Sstevel@tonic-gate */ 72*0Sstevel@tonic-gate 73*0Sstevel@tonic-gate #define TCP_TTL 60 /* default time to live for TCP segs */ 74*0Sstevel@tonic-gate /* 75*0Sstevel@tonic-gate * Time constants. 76*0Sstevel@tonic-gate */ 77*0Sstevel@tonic-gate #define TCPTV_MSL (30*PR_SLOWHZ) /* max seg lifetime (hah!) */ 78*0Sstevel@tonic-gate #define TCPTV_SRTTBASE 0 /* base roundtrip time; */ 79*0Sstevel@tonic-gate /* if 0, no idea yet */ 80*0Sstevel@tonic-gate #define TCPTV_SRTTDFLT (3*PR_SLOWHZ) /* assumed RTT if no info */ 81*0Sstevel@tonic-gate 82*0Sstevel@tonic-gate #define TCPTV_PERSMIN (5*PR_SLOWHZ) /* retransmit persistance */ 83*0Sstevel@tonic-gate #define TCPTV_PERSMAX (60*PR_SLOWHZ) /* maximum persist interval */ 84*0Sstevel@tonic-gate 85*0Sstevel@tonic-gate #define TCPTV_KEEP_INIT (75*PR_SLOWHZ) /* initial connect keep alive */ 86*0Sstevel@tonic-gate #define TCPTV_KEEP_IDLE (120*60*PR_SLOWHZ) /* dflt time before probing */ 87*0Sstevel@tonic-gate #define TCPTV_KEEPINTVL (75*PR_SLOWHZ) /* default probe interval */ 88*0Sstevel@tonic-gate #define TCPTV_KEEPCNT 8 /* max probes before drop */ 89*0Sstevel@tonic-gate 90*0Sstevel@tonic-gate #define TCPTV_MIN (1*PR_SLOWHZ) /* minimum allowable value */ 91*0Sstevel@tonic-gate #define TCPTV_REXMTMAX (64*PR_SLOWHZ) /* max allowable REXMT value */ 92*0Sstevel@tonic-gate 93*0Sstevel@tonic-gate #define TCP_LINGERTIME 120 /* linger at most 2 minutes */ 94*0Sstevel@tonic-gate 95*0Sstevel@tonic-gate #define TCP_MAXRXTSHIFT 12 /* maximum retransmits */ 96*0Sstevel@tonic-gate 97*0Sstevel@tonic-gate #ifdef TCPTIMERS 98*0Sstevel@tonic-gate char *tcptimers[] = 99*0Sstevel@tonic-gate { "REXMT", "PERSIST", "KEEP", "2MSL" }; 100*0Sstevel@tonic-gate #endif 101*0Sstevel@tonic-gate 102*0Sstevel@tonic-gate /* 103*0Sstevel@tonic-gate * Force a time value to be in a certain range. 104*0Sstevel@tonic-gate */ 105*0Sstevel@tonic-gate #define TCPT_RANGESET(tv, value, tvmin, tvmax) { \ 106*0Sstevel@tonic-gate (tv) = (value); \ 107*0Sstevel@tonic-gate if ((tv) < (tvmin)) \ 108*0Sstevel@tonic-gate (tv) = (tvmin); \ 109*0Sstevel@tonic-gate else if ((tv) > (tvmax)) \ 110*0Sstevel@tonic-gate (tv) = (tvmax); \ 111*0Sstevel@tonic-gate } 112*0Sstevel@tonic-gate 113*0Sstevel@tonic-gate #ifdef __cplusplus 114*0Sstevel@tonic-gate } 115*0Sstevel@tonic-gate #endif 116*0Sstevel@tonic-gate 117*0Sstevel@tonic-gate #endif /* _NETINET_TCP_TIMER_H */ 118