igmp.c

来自「基于组件方式开发操作系统的OSKIT源代码」· C语言 代码 · 共 627 行 · 第 1/2 页

		/*
		 * an old report
		 */
		++igmpstat.igps_rcv_reports;

		if (ifp->if_flags & IFF_LOOPBACK)
			break;

		if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr)) ||
		    igmp->igmp_group.s_addr != ip->ip_dst.s_addr) {
			++igmpstat.igps_rcv_badreports;
			m_freem(m);
			return;
		}

		/*
		 * KLUDGE: if the IP source address of the report has an
		 * unspecified (i.e., zero) subnet number, as is allowed for
		 * a booting host, replace it with the correct subnet number
		 * so that a process-level multicast routing demon can
		 * determine which subnet it arrived from.  This is necessary
		 * to compensate for the lack of any way for a process to
		 * determine the arrival interface of an incoming packet.
		 */
		if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0) {
			IFP_TO_IA(ifp, ia);
			if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet);
		}

		/*
		 * If we belong to the group being reported, stop
		 * our timer for that group.
		 */
		IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm);

		if (inm != NULL) {
		  inm->inm_timer = 0;
		  ++igmpstat.igps_rcv_ourreports;
		  
		  switch(inm->inm_state){
		  case IGMP_IDLE_MEMBER:
		  case IGMP_LAZY_MEMBER:
		  case IGMP_AWAKENING_MEMBER:
		  case IGMP_SLEEPING_MEMBER:
		    inm->inm_state = IGMP_SLEEPING_MEMBER;
		    break;
		  case IGMP_DELAYING_MEMBER:
		    if (inm->inm_rti->type == IGMP_OLD_ROUTER)
			inm->inm_state = IGMP_LAZY_MEMBER;
		    else
			inm->inm_state = IGMP_SLEEPING_MEMBER;
		    break;
		  }
		}
	      
		break;

	      case IGMP_HOST_NEW_MEMBERSHIP_REPORT:
		/*
		 * a new report
		 */

		/*
		 * We can get confused and think there's someone
		 * else out there if we are a multicast router.
		 * For fast leave to work, we have to know that
		 * we are the only member.
		 */
		IFP_TO_IA(ifp, ia);
		if (ia && ip->ip_src.s_addr == IA_SIN(ia)->sin_addr.s_addr)
			break;

		++igmpstat.igps_rcv_reports;
    
		if (ifp->if_flags & IFF_LOOPBACK)
		  break;
		
		if (!IN_MULTICAST(ntohl(igmp->igmp_group.s_addr)) ||
		    igmp->igmp_group.s_addr != ip->ip_dst.s_addr) {
		  ++igmpstat.igps_rcv_badreports;
		  m_freem(m);
		  return;
		}
		
		/*
		 * KLUDGE: if the IP source address of the report has an
		 * unspecified (i.e., zero) subnet number, as is allowed for
		 * a booting host, replace it with the correct subnet number
		 * so that a process-level multicast routing demon can
		 * determine which subnet it arrived from.  This is necessary
		 * to compensate for the lack of any way for a process to
		 * determine the arrival interface of an incoming packet.
		 */
		if ((ntohl(ip->ip_src.s_addr) & IN_CLASSA_NET) == 0) {
/* #ifndef MROUTING XXX - I don't think the ifdef is necessary */
		  IFP_TO_IA(ifp, ia);
/* #endif */
		  if (ia) ip->ip_src.s_addr = htonl(ia->ia_subnet);
		}
		
		/*
		 * If we belong to the group being reported, stop
		 * our timer for that group.
		 */
		IN_LOOKUP_MULTI(igmp->igmp_group, ifp, inm);
		if (inm != NULL) {
		  inm->inm_timer = 0;
		  ++igmpstat.igps_rcv_ourreports;
		  
		  switch(inm->inm_state){
		  case IGMP_DELAYING_MEMBER:
		  case IGMP_IDLE_MEMBER:
		    inm->inm_state = IGMP_LAZY_MEMBER;
		    break;
		  case IGMP_AWAKENING_MEMBER:
		    inm->inm_state = IGMP_LAZY_MEMBER;
		    break;
		  case IGMP_LAZY_MEMBER:
		  case IGMP_SLEEPING_MEMBER:
		    break;
		  }
		}
	}

	/*
	 * Pass all valid IGMP packets up to any process(es) listening
	 * on a raw IGMP socket.
	 */
	rip_input(m);
}

void
igmp_joingroup(inm)
	struct in_multi *inm;
{
	int s = splnet();

	inm->inm_state = IGMP_IDLE_MEMBER;

	if ((inm->inm_addr.s_addr & igmp_local_group_mask) == igmp_local_group
	    || inm->inm_ifp->if_flags & IFF_LOOPBACK)
		inm->inm_timer = 0;
	else {
		igmp_sendpkt(inm,fill_rti(inm));
		inm->inm_timer = IGMP_RANDOM_DELAY(
					IGMP_MAX_HOST_REPORT_DELAY*PR_FASTHZ);
		inm->inm_state = IGMP_DELAYING_MEMBER;
		igmp_timers_are_running = 1;
	}
	splx(s);
}

void
igmp_leavegroup(inm)
	struct in_multi *inm;
{
         switch(inm->inm_state) {
	 case IGMP_DELAYING_MEMBER:
	 case IGMP_IDLE_MEMBER:
	   if (((inm->inm_addr.s_addr & igmp_local_group_mask) 
		!= igmp_local_group)
	       && !(inm->inm_ifp->if_flags & IFF_LOOPBACK))
	       if (inm->inm_rti->type != IGMP_OLD_ROUTER)
		   igmp_sendleave(inm);
	   break;
	 case IGMP_LAZY_MEMBER:
	 case IGMP_AWAKENING_MEMBER:
	 case IGMP_SLEEPING_MEMBER:
	   break;
	 }
}

void
igmp_fasttimo()
{
	register struct in_multi *inm;
	struct in_multistep step;
	int s;

	/*
	 * Quick check to see if any work needs to be done, in order
	 * to minimize the overhead of fasttimo processing.
	 */

	if (!igmp_timers_are_running)
		return;

	s = splnet();
	igmp_timers_are_running = 0;
	IN_FIRST_MULTI(step, inm);
	while (inm != NULL) {
		if (inm->inm_timer == 0) {
			/* do nothing */
		} else if (--inm->inm_timer == 0) {
		  if (inm->inm_state == IGMP_DELAYING_MEMBER) {
		    if (inm->inm_rti->type == IGMP_OLD_ROUTER)
			igmp_sendpkt(inm, IGMP_HOST_MEMBERSHIP_REPORT);
		    else
			igmp_sendpkt(inm, IGMP_HOST_NEW_MEMBERSHIP_REPORT);
		    inm->inm_state = IGMP_IDLE_MEMBER;
		  }
		} else {
			igmp_timers_are_running = 1;
		}
		IN_NEXT_MULTI(step, inm);
	}
	splx(s);
}

void
igmp_slowtimo()
{
	int s = splnet();
	register struct router_info *rti =  Head;

#ifdef IGMP_DEBUG
	printf("[igmp.c,_slowtimo] -- > entering \n");
#endif
	while (rti) {
		rti->time ++;
		if (rti->time >= IGMP_AGE_THRESHOLD){
			rti->type = IGMP_NEW_ROUTER;
			rti->time = IGMP_AGE_THRESHOLD;
		}
		rti = rti->next;
	}
#ifdef IGMP_DEBUG	
	printf("[igmp.c,_slowtimo] -- > exiting \n");
#endif
	splx(s);
}

static void
igmp_sendpkt(inm, type)
	struct in_multi *inm;
	int type;
{
        struct mbuf *m;
        struct igmp *igmp;
        struct ip *ip;
        struct ip_moptions *imo;

        MGETHDR(m, M_DONTWAIT, MT_HEADER);
        if (m == NULL)
                return;

	MALLOC(imo, struct ip_moptions *, sizeof *imo, M_IPMOPTS, M_DONTWAIT);
	if (!imo) {
		m_free(m);
		return;
	}

	m->m_pkthdr.rcvif = loif;
	m->m_pkthdr.len = sizeof(struct ip) + IGMP_MINLEN;
	MH_ALIGN(m, IGMP_MINLEN + sizeof(struct ip));
	m->m_data += sizeof(struct ip);
        m->m_len = IGMP_MINLEN;
        igmp = mtod(m, struct igmp *);
        igmp->igmp_type   = type;
        igmp->igmp_code   = 0;
        igmp->igmp_group  = inm->inm_addr;
        igmp->igmp_cksum  = 0;
        igmp->igmp_cksum  = in_cksum(m, IGMP_MINLEN);

        m->m_data -= sizeof(struct ip);
        m->m_len += sizeof(struct ip);
        ip = mtod(m, struct ip *);
        ip->ip_tos        = 0;
        ip->ip_len        = sizeof(struct ip) + IGMP_MINLEN;
        ip->ip_off        = 0;
        ip->ip_p          = IPPROTO_IGMP;
        ip->ip_src.s_addr = INADDR_ANY;
        ip->ip_dst        = igmp->igmp_group;

        imo->imo_multicast_ifp  = inm->inm_ifp;
        imo->imo_multicast_ttl  = 1;
	imo->imo_multicast_vif  = -1;
        /*
         * Request loopback of the report if we are acting as a multicast
         * router, so that the process-level routing demon can hear it.
         */
        imo->imo_multicast_loop = (ip_mrouter != NULL);

        ip_output(m, (struct mbuf *)0, (struct route *)0, 0, imo);

	FREE(imo, M_IPMOPTS);
        ++igmpstat.igps_snd_reports;
}

static void
igmp_sendleave(inm)
	struct in_multi *inm;
{
	igmp_sendpkt(inm, IGMP_HOST_LEAVE_MESSAGE);
}

int
igmp_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp,
	    void *newp, size_t newlen)
{
	/* All sysctl names at this level are terminal. */
	if (namelen != 1)
		return ENOTDIR;	/* XXX overloaded */

	switch(name[0]) {
	case IGMPCTL_STATS:
		return sysctl_rdstruct(oldp, oldlenp, newp, &igmpstat, 
				       sizeof igmpstat);
	default:
		return ENOPROTOOPT;
	}
}