4.1cBSD/usr/src/ucb/netser/routed/timer.c

#ifndef lint
static char sccsid[] = "@(#)timer.c	4.2 1/11/83";
#endif

/*
 * Routing Table Management Daemon
 */
#include "defs.h"

int	timeval = -TIMER_RATE;

/*
 * 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;

	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 that for our only interface. 
			 * The latter is excused because we don't act as
			 * a routing information supplier and hence would
			 * time it out.  This is fair as if it's down
			 * we're cut off from the world anyway and it's
			 * not likely we'll grow any new hardware in
			 * the mean time.
			 */
			if (!(rt->rt_state & RTS_PASSIVE) &&
			    (supplier || !(rt->rt_state & RTS_INTERFACE)))
				rt->rt_timer += TIMER_RATE;
			if (rt->rt_timer >= EXPIRE_TIME)
				rt->rt_metric = HOPCNT_INFINITY;
			if (rt->rt_timer >= GARBAGE_TIME) {
				rt = rt->rt_back;
				rtdelete(rt->rt_forw);
				continue;
			}
			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_nets[0].rip_dst = rt->rt_dst;
				msg->rip_nets[0].rip_metric =
				    min(rt->rt_metric+1, HOPCNT_INFINITY);
				toall(sendmsg);
			}
		}
	}
	if (doinghost) {
		doinghost = 0;
		base = nethash;
		goto again;
	}
	if (timetobroadcast)
		toall(supply);
	alarm(TIMER_RATE);
}