/* hgjoin.c - hgjoin */
#include <conf.h>
#include <kernel.h>
#include <network.h>
#include <sleep.h>
#include <igmp.h>
/*------------------------------------------------------------------------
* hgjoin - handle application request to join a host group
*------------------------------------------------------------------------
*/
int
hgjoin(unsigned ifnum, IPaddr ipa, Bool islocal)
{
struct hg *phg;
int i;
if (!IP_CLASSD(ipa))
return SYSERR;
/* restrict multicast in multi-homed host to primary interface */
if (ifnum != NI_PRIMARY)
return SYSERR;
wait(HostGroup.hi_mutex);
if (phg = hglookup(ifnum, ipa)) {
phg->hg_refs++;
signal(HostGroup.hi_mutex);
return OK; /* already in it */
}
signal(HostGroup.hi_mutex);
/* add to host group and routing tables */
if (hgadd(ifnum, ipa, islocal) == SYSERR)
return SYSERR;
rtadd(ipa, ip_maskall, ipa, 0, NI_LOCAL, RT_INF);
/*
* advertise membership to multicast router(s); don't advertise
* 224.0.0.1 (all multicast hosts) membership.
*/
if (ipa != ig_allhosts)
for (i=0; i < IG_NSEND; ++i) {
igmp(IGT_HREPORT, ifnum, ipa);
sleep10(IG_DELAY);
}
return OK;
}
igmp.rar （26个子文件） 
igmp 
igmp.c 1KB hgleave.c 784B igmp_settimers.c 679B hgrand.c 642B hgarpadd.c 995B hginit.c 807B RCS igmp_update.c,v 838B hginit.c,v 965B igmp.c,v 1KB hgleave.c,v 984B hgarpadd.c,v 1KB igmp_settimers.c,v 870B hglookup.c,v 894B hgjoin.c,v 1KB hgrand.c,v 818B hgarpdel.c,v 856B hgadd.c,v 1KB hgprint.c,v 1KB igmp_in.c,v 1KB hgprint.c 1KB hgjoin.c 1KB igmp_update.c 681B igmp_in.c 1KB hgadd.c 1KB hgarpdel.c 729B hglookup.c 633B资源评论
