4.2BSD/usr/src/etc/routed/input.c

#ifndef lint
static char sccsid[] = "@(#)input.c	4.5 (Berkeley) 6/1/83";
#endif

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

/*
 * Process a newly received packet.
 */
rip_input(from, size)
	struct sockaddr *from;
	int size;
{
	struct rt_entry *rt;
	struct netinfo *n;
	struct interface *ifp;
	int newsize;
	struct afswitch *afp;

	ifp = 0;
	TRACE_INPUT(ifp, from, size);
	if (from->sa_family >= AF_MAX)
		return;
	afp = &afswitch[from->sa_family];
	switch (msg->rip_cmd) {

	case RIPCMD_REQUEST:
		newsize = 0;
		size -= 4 * sizeof (char);
		n = msg->rip_nets;
		while (size > 0) {
			if (size < sizeof (struct netinfo))
				break;
			size -= sizeof (struct netinfo);

			if (msg->rip_vers > 0) {
				n->rip_dst.sa_family =
					ntohs(n->rip_dst.sa_family);
				n->rip_metric = ntohl(n->rip_metric);
			}
			/* 
			 * A single entry with sa_family == AF_UNSPEC and
			 * metric ``infinity'' means ``all routes''.
			 */
			if (n->rip_dst.sa_family == AF_UNSPEC &&
			    n->rip_metric == HOPCNT_INFINITY && size == 0) {
				supply(from, 0, ifp);
				return;
			}
			rt = rtlookup(&n->rip_dst);
			n->rip_metric = rt == 0 ? HOPCNT_INFINITY :
				min(rt->rt_metric+1, HOPCNT_INFINITY);
			if (msg->rip_vers > 0) {
				n->rip_dst.sa_family =
					htons(n->rip_dst.sa_family);
				n->rip_metric = htonl(n->rip_metric);
			}
			n++, newsize += sizeof (struct netinfo);
		}
		if (newsize > 0) {
			msg->rip_cmd = RIPCMD_RESPONSE;
			newsize += sizeof (int);
			(*afp->af_output)(s, 0, from, newsize);
		}
		return;

	case RIPCMD_TRACEON:
	case RIPCMD_TRACEOFF:
		/* verify message came from a priviledged port */
		if ((*afp->af_portcheck)(from) == 0)
			return;
		packet[size] = '\0';
		if (msg->rip_cmd == RIPCMD_TRACEON)
			traceon(msg->rip_tracefile);
		else
			traceoff();
		return;

	case RIPCMD_RESPONSE:
		/* verify message came from a router */
		if ((*afp->af_portmatch)(from) == 0)
			return;
		(*afp->af_canon)(from);
		/* are we talking to ourselves? */
		ifp = if_ifwithaddr(from);
		if (ifp) {
			rt = rtfind(from);
			if (rt == 0)
				addrouteforif(ifp);
			else
				rt->rt_timer = 0;
			return;
		}
		size -= 4 * sizeof (char);
		n = msg->rip_nets;
		for (; size > 0; size -= sizeof (struct netinfo), n++) {
			if (size < sizeof (struct netinfo))
				break;
			if (msg->rip_vers > 0) {
				n->rip_dst.sa_family =
					ntohs(n->rip_dst.sa_family);
				n->rip_metric = ntohl(n->rip_metric);
			}
			if (n->rip_metric >= HOPCNT_INFINITY)
				continue;
			rt = rtlookup(&n->rip_dst);
			if (rt == 0) {
				rtadd(&n->rip_dst, from, n->rip_metric, 0);
				continue;
			}

			/*
			 * Update if from gateway, shorter, or getting
			 * stale and equivalent.
			 */
			if (equal(from, &rt->rt_router) ||
			    n->rip_metric < rt->rt_metric ||
			    (rt->rt_timer > (EXPIRE_TIME/2) &&
			    rt->rt_metric == n->rip_metric)) {
				rtchange(rt, from, n->rip_metric);
				rt->rt_timer = 0;
			}
		}
		return;
	}
}