diff options
Diffstat (limited to 'sys/netinet/tcp_timer.c')
| -rw-r--r-- | sys/netinet/tcp_timer.c | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/sys/netinet/tcp_timer.c b/sys/netinet/tcp_timer.c new file mode 100644 index 0000000..0c0f0f8 --- /dev/null +++ b/sys/netinet/tcp_timer.c @@ -0,0 +1,312 @@ +/* + * 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 + */ + +#ifndef TUBA_INCLUDE +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/malloc.h> +#include <sys/mbuf.h> +#include <sys/socket.h> +#include <sys/socketvar.h> +#include <sys/protosw.h> +#include <sys/errno.h> + +#include <net/if.h> +#include <net/route.h> + +#include <netinet/in.h> +#include <netinet/in_systm.h> +#include <netinet/ip.h> +#include <netinet/in_pcb.h> +#include <netinet/ip_var.h> +#include <netinet/tcp.h> +#include <netinet/tcp_fsm.h> +#include <netinet/tcp_seq.h> +#include <netinet/tcp_timer.h> +#include <netinet/tcp_var.h> +#include <netinet/tcpip.h> + +int tcp_keepidle = TCPTV_KEEP_IDLE; +int tcp_keepintvl = TCPTV_KEEPINTVL; +int tcp_maxidle; +#endif /* TUBA_INCLUDE */ +/* + * Fast timeout routine for processing delayed acks + */ +void +tcp_fasttimo() +{ + register struct inpcb *inp; + register struct tcpcb *tp; + int s = splnet(); + + inp = tcb.inp_next; + if (inp) + for (; inp != &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; + tcpstat.tcps_delack++; + (void) tcp_output(tp); + } + splx(s); +} + +/* + * 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 +tcp_slowtimo() +{ + register struct inpcb *ip, *ipnxt; + register struct tcpcb *tp; + int s = splnet(); + register int i; + + tcp_maxidle = TCPTV_KEEPCNT * tcp_keepintvl; + /* + * Search through tcb's and update active timers. + */ + ip = tcb.inp_next; + if (ip == 0) { + splx(s); + return; + } + for (; ip != &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) { + (void) tcp_usrreq(tp->t_inpcb->inp_socket, + PRU_SLOWTIMO, (struct mbuf *)0, + (struct mbuf *)i, (struct mbuf *)0); + if (ipnxt->inp_prev != ip) + goto tpgone; + } + } + tp->t_idle++; + if (tp->t_rtt) + tp->t_rtt++; +tpgone: + ; + } + tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ +#ifdef TCP_COMPAT_42 + if ((int)tcp_iss < 0) + tcp_iss = 0; /* XXX */ +#endif + tcp_now++; /* for timestamps */ + splx(s); +} +#ifndef TUBA_INCLUDE + +/* + * Cancel all timers for TCP tp. + */ +void +tcp_canceltimers(tp) + struct tcpcb *tp; +{ + register int i; + + for (i = 0; i < TCPT_NTIMERS; i++) + tp->t_timer[i] = 0; +} + +int tcp_backoff[TCP_MAXRXTSHIFT + 1] = + { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 }; + +/* + * TCP timer processing. + */ +struct tcpcb * +tcp_timers(tp, timer) + register struct tcpcb *tp; + int timer; +{ + register int rexmt; + + 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 <= tcp_maxidle) + tp->t_timer[TCPT_2MSL] = tcp_keepintvl; + else + tp = tcp_close(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: + if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { + tp->t_rxtshift = TCP_MAXRXTSHIFT; + tcpstat.tcps_timeoutdrop++; + tp = tcp_drop(tp, tp->t_softerror ? + tp->t_softerror : ETIMEDOUT); + break; + } + tcpstat.tcps_rexmttimeo++; + rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; + TCPT_RANGESET(tp->t_rxtcur, rexmt, + tp->t_rttmin, TCPTV_REXMTMAX); + 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_maxseg; + tp->snd_ssthresh = win * tp->t_maxseg; + tp->t_dupacks = 0; + } + (void) tcp_output(tp); + break; + + /* + * Persistance timer into zero window. + * Force a byte to be output, if possible. + */ + case TCPT_PERSIST: + tcpstat.tcps_persisttimeo++; + tcp_setpersist(tp); + tp->t_force = 1; + (void) 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: + tcpstat.tcps_keeptimeo++; + if (tp->t_state < TCPS_ESTABLISHED) + goto dropit; + if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE && + tp->t_state <= TCPS_CLOSE_WAIT) { + if (tp->t_idle >= tcp_keepidle + 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. + */ + tcpstat.tcps_keepprobe++; +#ifdef TCP_COMPAT_42 + /* + * The keepalive packet must have nonzero length + * to get a 4.2 host to respond. + */ + tcp_respond(tp, tp->t_template, (struct mbuf *)NULL, + tp->rcv_nxt - 1, tp->snd_una - 1, 0); +#else + tcp_respond(tp, tp->t_template, (struct mbuf *)NULL, + 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: + tcpstat.tcps_keepdrops++; + tp = tcp_drop(tp, ETIMEDOUT); + break; + } + return (tp); +} +#endif /* TUBA_INCLUDE */ |
