igmp_in.c

来自「TCP-IP红宝书源代码」· C语言 代码 · 共 49 行

/* igmp_in.c - igmp_in */

#include <conf.h>
#include <kernel.h>
#include <network.h>
#include <igmp.h>

/*------------------------------------------------------------------------
 *  igmp_in  -  handle IGMP packet coming in from the network
 *------------------------------------------------------------------------
 */
int
igmp_in(struct netif *pni, struct ep *pep)
{
	struct	ip	*pip;
	struct	igmp	*pig;
	struct	hg	*phg;
	int		ifnum = pni - &nif[0];
	int		i, len;

	pip = (struct ip *)pep->ep_data;
	pig = (struct igmp *) pip->ip_data;

	len = pip->ip_len - IP_HLEN(pip);
	if (len != IG_HLEN || IG_VER(pig) != IG_VERSION ||
	    cksum((WORD *)pig, len>>1)) {
		freebuf(pep);
		return SYSERR;
	}
	switch(IG_TYP(pig)) {
	case IGT_HQUERY:
		igmp_settimers(NI_PRIMARY);
		break;
	case IGT_HREPORT:
		wait(HostGroup.hi_mutex);
		if ((phg = hglookup(NI_PRIMARY, pig->ig_gaddr)) &&
		    phg->hg_state == HGS_DELAYING) {
			tmclear(HostGroup.hi_uport, phg);
			phg->hg_state = HGS_IDLE;
		}
		signal(HostGroup.hi_mutex);
		break;
	default:
		break;
	}
	freebuf(pep);
	return OK;
}