timer.c

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· C语言 代码 · 共 171 行

#ifndef lint
static  char    *sccsid = "@(#)timer.c	4.1  (ULTRIX)        7/2/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1984,1988 by			*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   This software is  derived  from  software  received  from  the	*
 *   University    of   California,   Berkeley,   and   from   Bell	*
 *   Laboratories.  Use, duplication, or disclosure is  subject  to	*
 *   restrictions  under  license  agreements  with  University  of	*
 *   California and with AT&T.						*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/
/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

/************************************************************************
 *			Modification History				*
 *
 * 07/07/89	R. Bhanukitsiri
 *		Decrease the frequency of SNMP registry.
 *
 * 06/01/89	R. Bhanukitsiri
 *		Don't register SNMP variables if no SNMP socket.
 *
 * 03/09/89	R. Bhanukitsiri
 *		Register our SNMP variables every timer interval.
 *									*
 ************************************************************************/

/*
#ifndef lint
static char sccsid[] = "timer.c	5.4 (Berkeley) 4/2/87";
#endif not lint
*/
/*
 * Routing Table Management Daemon
 */
#include "defs.h"

#ifdef	SNMP
extern	int snmp_socket;
#endif	SNMP

int	timeval = -TIMER_RATE;
#ifdef	SNMP
int	snmptimer = SNMP_TIME;		/* SNMP registration interval time */
#endif	SNMP

/*
 * Timer routine.  Performs routing information supply
 * duties and manages timers on routing table entries.
 */
timer()
{
	register struct rthash *rh;
	register struct rt_entry *rt;
	struct rthash *base = hosthash;
	int doinghost = 1, timetobroadcast;
	extern int externalinterfaces;

	timeval += TIMER_RATE;
	if (lookforinterfaces && (timeval % CHECK_INTERVAL) == 0)
		ifinit();
	timetobroadcast = supplier && (timeval % SUPPLY_INTERVAL) == 0;
again:
	for (rh = base; rh < &base[ROUTEHASHSIZ]; rh++) {
		rt = rh->rt_forw;
		for (; rt != (struct rt_entry *)rh; rt = rt->rt_forw) {
			/*
			 * We don't advance time on a routing entry for
			 * a passive gateway, or any interface if we're
			 * not acting as supplier.
			 */
/* Supplier may have to go here! */
			if (!(rt->rt_state & RTS_PASSIVE) &&
			    (supplier || !(rt->rt_state & RTS_INTERFACE)))
				rt->rt_timer += TIMER_RATE;
			if (rt->rt_timer >= GARBAGE_TIME) {
				rt = rt->rt_back;
				rtdelete(rt->rt_forw);
				continue;
			}
			if (rt->rt_timer >= EXPIRE_TIME)
				rtchange(rt, &rt->rt_router, HOPCNT_INFINITY);
			if (rt->rt_state & RTS_CHANGED) {
				rt->rt_state &= ~RTS_CHANGED;
				/* don't send extraneous packets */
				if (!supplier || timetobroadcast)
					continue;
				msg->rip_cmd = RIPCMD_RESPONSE;
				msg->rip_vers = RIPVERSION;
				msg->rip_nets[0].rip_dst = rt->rt_dst;
				msg->rip_nets[0].rip_dst.sa_family =
				   htons(msg->rip_nets[0].rip_dst.sa_family);
				msg->rip_nets[0].rip_metric =
				   htonl(min(rt->rt_metric + rt->rt_ifmetric,
				   HOPCNT_INFINITY));
				toall(sendmsg);
			}
		}
	}
	if (doinghost) {
		doinghost = 0;
		base = nethash;
		goto again;
	}
	if (timetobroadcast)
		toall(supply);
#ifdef	SNMP
	/*
	 * Since we don't know if the SNMP Agent is alive, we send a message
	 * to SNMPD every timer interval to register our SNMP variables.
	 */
	snmptimer += TIMER_RATE;
	if (snmptimer >= SNMP_TIME) {
		if (snmp_socket != -1) register_snmp_vars();
		snmptimer = 0;
	}
#endif	SNMP
	alarm(TIMER_RATE);
}

/*
 * On hangup, let everyone know we're going away.
 */
hup()
{
	register struct rthash *rh;
	register struct rt_entry *rt;
	struct rthash *base = hosthash;
	int doinghost = 1;

	if (supplier) {
again:
		for (rh = base; rh < &base[ROUTEHASHSIZ]; rh++) {
			rt = rh->rt_forw;
			for (; rt != (struct rt_entry *)rh; rt = rt->rt_forw)
				rt->rt_metric = HOPCNT_INFINITY;
		}
		if (doinghost) {
			doinghost = 0;
			base = nethash;
			goto again;
		}
		toall(supply);
	}
	exit(1);
}