/* * btcp_timer.c * * Derived from: * * Copyright (c) 1982, 1986, 1988, 1990, 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.c 8.1 (Berkeley) 6/10/93 * * Modified for x-kernel v3.3 * Modifications Copyright (c) 1996,1991 Arizona Board of Regents * * $Revision: 1.3 $ * $Date: 1996/06/14 21:28:21 $ */ #include "xkernel.h" #include "tcp_internal.h" #include "tcp_fsm.h" #include "tcp_seq.h" #include "tcp_timer.h" #include "tcp_var.h" #include "tcpip.h" #include "btcp.h" static int tcpnodelack = 0; static int mytrace = 0; static int tcp_keepidle = TCPTV_KEEP_IDLE; /* LSB: Changed next one for simulator! */ static int tcp_keepintvl = 6 /* TCPTV_KEEPINTVL */; /* static int tcp_maxidle; */ /* * Fast timeout routine for processing delayed acks */ void btcp_fasttimo( ev, arg) Event ev; VOID *arg; { register struct inpcb *inp; register struct tcpcb *tp; PSTATE *ps=(PSTATE *)arg; /* * The original code protected this routine with splnet(). If the timeout * thread blocks, there could be a problem. */ /* int s = splnet(); */ DO_TRACE(ps, TCP_EVENT_FAST_TO, tcpGetTime(), 0, 0); inp = ps->tcb.inp_next; if (inp) for (; inp != &ps->tcb; inp = inp->inp_next) if ((tp = (struct tcpcb *)inp->inp_ppcb) && (tp->t_flags & TF_DELACK)) { tp->t_flags &= ~TF_DELACK; tp->t_flags |= TF_ACKNOW; ps->tcpstat.tcps_delack++; /* What if this blocks??? */ (void) (ps->tcp_output)(tp); } /* splx(s); */ evDetach(evSchedule(btcp_fasttimo, (void *)ps, TCP_FAST_INTERVAL)); } /* * Tcp protocol timeout routine called every 500 ms. Updates the timers in all * active tcb's and causes finite state machine actions if timers expire. */ void btcp_slowtimo(ev, arg) Event ev; VOID *arg; { register struct inpcb *ip, *ipnxt; register struct tcpcb *tp; PSTATE *ps=(PSTATE *)arg; /* * The original code protected this routine with splnet(). If the timeout * thread blocks, there could be a problem. */ /* int s = splnet(); */ register int i; DO_TRACE(ps, TCP_EVENT_SLOW_TO, tcpGetTime(), 0, 0); ps->tcp_maxidle = TCPTV_KEEPCNT * tcp_keepintvl; /* Search through tcb's and update active timers. */ ip = ps->tcb.inp_next; if (ip != 0) { for (; ip != &ps->tcb; ip = ipnxt) { ipnxt = ip->inp_next; tp = intotcpcb(ip); if (tp == 0) continue; for (i = 0; i < TCPT_NTIMERS; i++) { if (tp->t_timer[i] && --tp->t_timer[i] == 0) { /* What if this blocks??? */ (void)btcp_usrreq(tp->t_inpcb->inp_session, PRU_SLOWTIMO, (Msg *)0, (Msg *)i); if (ipnxt->inp_prev != ip) goto tpgone; } } tp->t_idle++; if (tp->t_rtt) tp->t_rtt++; tpgone: ; } ps->tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ #ifdef TCP_COMPAT_42 if ((int)ps->tcp_iss < 0) ps->tcp_iss = 0; /* XXX */ #endif ps->tcp_now++; /* for timestamps */ } /* splx(s); */ evDetach(evSchedule(btcp_slowtimo, (void *)ps, TCP_SLOW_INTERVAL)); } #ifndef TUBA_INCLUDE /* * Cancel all timers for TCP tp. */ void btcp_canceltimers(tp) struct tcpcb *tp; { register int i; for (i = 0; i < TCPT_NTIMERS; i++) tp->t_timer[i] = 0; } #ifndef XNETSIM int tcp_backoff[TCP_MAXRXTSHIFT + 1] = { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 }; #endif /* * TCP timer processing. */ struct tcpcb * btcp_timers(tp, timer, arg) register struct tcpcb *tp; int timer; void *arg; { register int rexmt; PSTATE *ps=(PSTATE *)arg; Protl self=tp->t_inpcb->inp_session->myprotl; struct tcpstate *tcpst; tcpst = tcpcbtoso(tp)->state; DO_TRACE(ps, TCP_EVENT_TIMER, tcpGetTime(), timer, tcpst->tid); switch (timer) { /* * 2 MSL timeout in shutdown went off. If we're closed but still * waiting for peer to close and connection has been idle too long, or * if 2MSL time is up from TIME_WAIT, delete connection control block. * Otherwise, check again in a bit. */ case TCPT_2MSL: if (tp->t_state != TCPS_TIME_WAIT && tp->t_idle <= ps->tcp_maxidle) tp->t_timer[TCPT_2MSL] = tcp_keepintvl/2; /* LSB added /2 */ else tp = btcp_destroy(tp); break; /* * Retransmission timer went off. Message has not been acked within * retransmit interval. Back off to a longer retransmit interval and * retransmit one segment. */ case TCPT_REXMT: xTrace1(tcpp, 4, "btcp: retransmission timeout (%d)", tp->t_rxtshift); if (tp->v_other14 < tp->t_rxtcur) tp->v_other14 = tp->t_rxtcur; if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { xTrace0(tcpp, 4, "btcp: too many rexmits, dropping"); tp->t_rxtshift = TCP_MAXRXTSHIFT; ps->tcpstat.tcps_timeoutdrop++; tp = btcp_drop(tp, tp->t_softerror ? tp->t_softerror : ETIMEDOUT); break; } ps->tcpstat.tcps_rexmttimeo++; /* LSB: prev vers do TCP_REXMTVAL(tp) >> 1 ! */ #ifdef FIX_2 rexmt = (((tp->t_srtt >> 3) + tp->t_rttvar) >> 2) * tcp_backoff[tp->t_rxtshift]; #else rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; #endif TCPT_RANGESET(tp->t_rxtcur, rexmt, tp->t_rttmin, TCPTV_REXMTMAX); DO_TRACE(ps, TCP_EVENT_OTHER9, tp->t_rxtcur, 4, tcpst->tid); tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; /* * If losing, let the lower level know and try for a better route. * Also, if we backed off this far, our srtt estimate is probably * bogus. Clobber it so we'll take the next rtt measurement as our * srtt; move the current srtt into rttvar to keep the current * retransmit times until then. */ if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { /* in_losing(tp->t_inpcb); */ tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); tp->t_srtt = 0; } tp->snd_nxt = tp->snd_una; /* * If timing a segment in this window, stop the timer. */ tp->t_rtt = 0; /* * Close the congestion window down to one segment (we'll open it * by one segment for each ack we get). Since we probably have a * window's worth of unacked data accumulated, this "slow start" * keeps us from dumping all that data as back-to-back packets * (which might overwhelm an intermediate gateway). * * There are two phases to the opening: Initially we open by one * mss on each ack. This makes the window size increase * exponentially with time. If the window is larger than the path * can handle, this exponential growth results in dropped packet(s) * almost immediately. To get more time between drops but still * "push" the network to take advantage of improving conditions, we * switch from exponential to linear window opening at some * threshhold size. For a threshhold, we use half the current * window size, truncated to a multiple of the mss. * * (the minimum cwnd that will give us exponential growth is 2 mss. * We don't allow the threshhold to go below this.) */ { u_int win = MIN(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg; if (win < 2) win = 2; tp->snd_cwnd = tp->t_slowstart * tp->t_maxseg; tp->snd_ssthresh = win * tp->t_maxseg; tp->t_dupacks = 0; } (void) (ps->tcp_output)(tp); break; /* * Persistance timer into zero window. Force a byte to be output, * if possible. */ case TCPT_PERSIST: ps->tcpstat.tcps_persisttimeo++; tcp_setpersist(tp); tp->t_force = 1; (void) (ps->tcp_output)(tp); tp->t_force = 0; break; /* * Keep-alive timer went off; send something or drop connection if * idle for too long. */ case TCPT_KEEP: ps->tcpstat.tcps_keeptimeo++; if (tp->t_state < TCPS_ESTABLISHED) goto dropit; /* LSB ? */ #define SHOULDDOKEEPS(X) 0 if (SHOULDDOKEEPS(tp->t_inpcb->inp_session) && tp->t_state <= TCPS_CLOSE_WAIT) { if (tp->t_idle >= tcp_keepidle + ps->tcp_maxidle) goto dropit; /* * Send a packet designed to force a response if the peer * is up and reachable: either an ACK if the connection is * still alive, or an RST if the peer has closed the * connection due to timeout or reboot. Using sequence * number tp->snd_una-1 causes the transmitted zero-length * segment to lie outside the receive window; by the * protocol spec, this requires the correspondent TCP to * respond. */ ps->tcpstat.tcps_keepprobe++; #ifdef TCP_COMPAT_42 /* * The keepalive packet must have nonzero length to get a * 4.2 host to respond. */ btcp_respond(self, tp, &tp->t_template->ti_t, &tp->t_template->ti_p, tp->rcv_nxt - 1, tp->snd_una - 1, 0); #else btcp_respond(self, tp, &tp->t_template->ti_t, &tp->t_template->ti_p, tp->rcv_nxt, tp->snd_una - 1, 0); #endif tp->t_timer[TCPT_KEEP] = tcp_keepintvl; } else tp->t_timer[TCPT_KEEP] = tcp_keepidle; break; dropit: ps->tcpstat.tcps_keepdrops++; tp = btcp_drop(tp, ETIMEDOUT); break; } return tp; } #endif /* TUBA_INCLUDE */