hgadd.c,v

来自「TCP-IP红宝书源代码」· C,V 代码 · 共 76 行

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date	97.09.21.19.26.58;	author dls;	state Dist;
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@/* hgadd.c - hgadd */

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

/*------------------------------------------------------------------------
 *  hgadd  -  add a host group entry for a group
 *------------------------------------------------------------------------
 */
int hgadd(ifnum, ipa, islocal)
int	ifnum;		/* interface for the host group	*/
IPaddr	ipa;		/* IP multicast address		*/
Bool	islocal;	/* true if this group is local	*/
{
	struct hg	*phg;
	static int	start;
	int		i;


	wait(HostGroup.hi_mutex);
	for (i=0; i < HG_TSIZE; ++i) {
		if (++start >= HG_TSIZE)
			start = 0;
		if (hgtable[start].hg_state == HGS_FREE)
			break;
	}
	phg = &hgtable[start];
	if (phg->hg_state != HGS_FREE) {
		signal(HostGroup.hi_mutex);
		return SYSERR;		/* table full */
	}
	if (hgarpadd(ifnum, ipa) == SYSERR) {
		signal(HostGroup.hi_mutex);
		return SYSERR;
	}
	phg->hg_ifnum = ifnum;
	phg->hg_refs = 1;
	if (islocal)
		phg->hg_ttl = 1;
	else
		phg->hg_ttl = IP_TTL;
	phg->hg_ipa = ipa;
	if (ipa == ig_allhosts)
		phg->hg_state = HGS_STATIC;
	else
		phg->hg_state = HGS_IDLE;
	signal(HostGroup.hi_mutex);
	return OK;
}
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