ip_output.c

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	}
	if (m->m_len > MAX_IPOPTLEN + sizeof(struct in_addr))
		goto bad;
	*pcbopt = m;
	return (0);

bad:
	(void)m_free(m);
	return (EINVAL);
}

/*
 * XXX
 * The whole multicast option thing needs to be re-thought.
 * Several of these options are equally applicable to non-multicast
 * transmission, and one (IP_MULTICAST_TTL) totally duplicates a
 * standard option (IP_TTL).
 */

/*
 * following RFC1724 section 3.3, 0.0.0.0/8 is interpreted as interface index.
 */
static struct ifnet *
ip_multicast_if(a, ifindexp)
	struct in_addr *a;
	int *ifindexp;
{
	int ifindex;
	struct ifnet *ifp;

	if (ifindexp)
		*ifindexp = 0;
	if (ntohl(a->s_addr) >> 24 == 0) {
		ifindex = ntohl(a->s_addr) & 0xffffff;
		if (ifindex < 0 || if_index < ifindex)
			return NULL;
		ifp = ifindex2ifnet[ifindex];
		if (ifindexp)
			*ifindexp = ifindex;
	} else {
		INADDR_TO_IFP(*a, ifp);
	}
	return ifp;
}

/*
 * Set the IP multicast options in response to user setsockopt().
 */
static int
ip_setmoptions(sopt, imop)
	struct sockopt *sopt;
	struct ip_moptions **imop;
{
	int error = 0;
	int i;
	struct in_addr addr;
	struct ip_mreq mreq;
	struct ifnet *ifp;
	struct ip_moptions *imo = *imop;
	struct route ro;
	struct sockaddr_in *dst;
	int ifindex;
	int s;

	if (imo == NULL) {
		/*
		 * No multicast option buffer attached to the pcb;
		 * allocate one and initialize to default values.
		 */
		imo = (struct ip_moptions*)malloc(sizeof(*imo), M_IPMOPTS,
		    M_WAITOK);

		if (imo == NULL)
			return (ENOBUFS);
		*imop = imo;
		imo->imo_multicast_ifp = NULL;
		imo->imo_multicast_addr.s_addr = INADDR_ANY;
		imo->imo_multicast_vif = -1;
		imo->imo_multicast_ttl = IP_DEFAULT_MULTICAST_TTL;
		imo->imo_multicast_loop = IP_DEFAULT_MULTICAST_LOOP;
		imo->imo_num_memberships = 0;
	}

	switch (sopt->sopt_name) {
	/* store an index number for the vif you wanna use in the send */
	case IP_MULTICAST_VIF:
		if (legal_vif_num == 0) {
			error = EOPNOTSUPP;
			break;
		}
		error = sooptcopyin(sopt, &i, sizeof i, sizeof i);
		if (error)
			break;
		if (!legal_vif_num(i) && (i != -1)) {
			error = EINVAL;
			break;
		}
		imo->imo_multicast_vif = i;
		break;

	case IP_MULTICAST_IF:
		/*
		 * Select the interface for outgoing multicast packets.
		 */
		error = sooptcopyin(sopt, &addr, sizeof addr, sizeof addr);
		if (error)
			break;
		/*
		 * INADDR_ANY is used to remove a previous selection.
		 * When no interface is selected, a default one is
		 * chosen every time a multicast packet is sent.
		 */
		if (addr.s_addr == INADDR_ANY) {
			imo->imo_multicast_ifp = NULL;
			break;
		}
		/*
		 * The selected interface is identified by its local
		 * IP address.  Find the interface and confirm that
		 * it supports multicasting.
		 */
		s = splimp();
		ifp = ip_multicast_if(&addr, &ifindex);
		if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
			splx(s);
			error = EADDRNOTAVAIL;
			break;
		}
		imo->imo_multicast_ifp = ifp;
		if (ifindex)
			imo->imo_multicast_addr = addr;
		else
			imo->imo_multicast_addr.s_addr = INADDR_ANY;
		splx(s);
		break;

	case IP_MULTICAST_TTL:
		/*
		 * Set the IP time-to-live for outgoing multicast packets.
		 * The original multicast API required a char argument,
		 * which is inconsistent with the rest of the socket API.
		 * We allow either a char or an int.
		 */
		if (sopt->sopt_valsize == 1) {
			u_char ttl;
			error = sooptcopyin(sopt, &ttl, 1, 1);
			if (error)
				break;
			imo->imo_multicast_ttl = ttl;
		} else {
			u_int ttl;
			error = sooptcopyin(sopt, &ttl, sizeof ttl, 
					    sizeof ttl);
			if (error)
				break;
			if (ttl > 255)
				error = EINVAL;
			else
				imo->imo_multicast_ttl = ttl;
		}
		break;

	case IP_MULTICAST_LOOP:
		/*
		 * Set the loopback flag for outgoing multicast packets.
		 * Must be zero or one.  The original multicast API required a
		 * char argument, which is inconsistent with the rest
		 * of the socket API.  We allow either a char or an int.
		 */
		if (sopt->sopt_valsize == 1) {
			u_char loop;
			error = sooptcopyin(sopt, &loop, 1, 1);
			if (error)
				break;
			imo->imo_multicast_loop = !!loop;
		} else {
			u_int loop;
			error = sooptcopyin(sopt, &loop, sizeof loop,
					    sizeof loop);
			if (error)
				break;
			imo->imo_multicast_loop = !!loop;
		}
		break;

	case IP_ADD_MEMBERSHIP:
		/*
		 * Add a multicast group membership.
		 * Group must be a valid IP multicast address.
		 */
		error = sooptcopyin(sopt, &mreq, sizeof mreq, sizeof mreq);
		if (error)
			break;

		if (!IN_MULTICAST(ntohl(mreq.imr_multiaddr.s_addr))) {
			error = EINVAL;
			break;
		}
		s = splimp();
		/*
		 * If no interface address was provided, use the interface of
		 * the route to the given multicast address.
		 */
		if (mreq.imr_interface.s_addr == INADDR_ANY) {
			bzero((caddr_t)&ro, sizeof(ro));
			dst = (struct sockaddr_in *)&ro.ro_dst;
			dst->sin_len = sizeof(*dst);
			dst->sin_family = AF_INET;
			dst->sin_addr = mreq.imr_multiaddr;
			rtalloc(&ro);
			if (ro.ro_rt == NULL) {
				error = EADDRNOTAVAIL;
				splx(s);
				break;
			}
			ifp = ro.ro_rt->rt_ifp;
			rtfree(ro.ro_rt);
		}
		else {
			ifp = ip_multicast_if(&mreq.imr_interface, NULL);
		}

		/*
		 * See if we found an interface, and confirm that it
		 * supports multicast.
		 */
		if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0) {
			error = EADDRNOTAVAIL;
			splx(s);
			break;
		}
		/*
		 * See if the membership already exists or if all the
		 * membership slots are full.
		 */
		for (i = 0; i < imo->imo_num_memberships; ++i) {
			if (imo->imo_membership[i]->inm_ifp == ifp &&
			    imo->imo_membership[i]->inm_addr.s_addr
						== mreq.imr_multiaddr.s_addr)
				break;
		}
		if (i < imo->imo_num_memberships) {
			error = EADDRINUSE;
			splx(s);
			break;
		}
		if (i == IP_MAX_MEMBERSHIPS) {
			error = ETOOMANYREFS;
			splx(s);
			break;
		}
		/*
		 * Everything looks good; add a new record to the multicast
		 * address list for the given interface.
		 */
		if ((imo->imo_membership[i] =
		    in_addmulti(&mreq.imr_multiaddr, ifp)) == NULL) {
			error = ENOBUFS;
			splx(s);
			break;
		}
		++imo->imo_num_memberships;
		splx(s);
		break;

	case IP_DROP_MEMBERSHIP:
		/*
		 * Drop a multicast group membership.
		 * Group must be a valid IP multicast address.
		 */
		error = sooptcopyin(sopt, &mreq, sizeof mreq, sizeof mreq);
		if (error)
			break;

		if (!IN_MULTICAST(ntohl(mreq.imr_multiaddr.s_addr))) {
			error = EINVAL;
			break;
		}

		s = splimp();
		/*
		 * If an interface address was specified, get a pointer
		 * to its ifnet structure.
		 */
		if (mreq.imr_interface.s_addr == INADDR_ANY)
			ifp = NULL;
		else {
			ifp = ip_multicast_if(&mreq.imr_interface, NULL);
			if (ifp == NULL) {
				error = EADDRNOTAVAIL;
				splx(s);
				break;
			}
		}
		/*
		 * Find the membership in the membership array.
		 */
		for (i = 0; i < imo->imo_num_memberships; ++i) {
			if ((ifp == NULL ||
			     imo->imo_membership[i]->inm_ifp == ifp) &&
			     imo->imo_membership[i]->inm_addr.s_addr ==
			     mreq.imr_multiaddr.s_addr)
				break;
		}
		if (i == imo->imo_num_memberships) {
			error = EADDRNOTAVAIL;
			splx(s);
			break;
		}
		/*
		 * Give up the multicast address record to which the
		 * membership points.
		 */
		in_delmulti(imo->imo_membership[i]);
		/*
		 * Remove the gap in the membership array.
		 */
		for (++i; i < imo->imo_num_memberships; ++i)
			imo->imo_membership[i-1] = imo->imo_membership[i];
		--imo->imo_num_memberships;
		splx(s);
		break;

	default:
		error = EOPNOTSUPP;
		break;
	}

	/*
	 * If all options have default values, no need to keep the mbuf.
	 */
	if (imo->imo_multicast_ifp == NULL &&
	    imo->imo_multicast_vif == -1 &&
	    imo->imo_multicast_ttl == IP_DEFAULT_MULTICAST_TTL &&
	    imo->imo_multicast_loop == IP_DEFAULT_MULTICAST_LOOP &&
	    imo->imo_num_memberships == 0) {
		free(*imop, M_IPMOPTS);
		*imop = NULL;
	}

	return (error);
}

/*
 * Return the IP multicast options in response to user getsockopt().
 */
static int
ip_getmoptions(sopt, imo)
	struct sockopt *sopt;
	register struct ip_moptions *imo;
{
	struct in_addr addr;
	struct in_ifaddr *ia;
	int error, optval;
	u_char coptval;

	error = 0;
	switch (sopt->sopt_name) {
	case IP_MULTICAST_VIF: 
		if (imo != NULL)
			optval = imo->imo_multicast_vif;
		else
			optval = -1;
		error = sooptcopyout(sopt, &optval, sizeof optval);
		break;

	case IP_MULTICAST_IF:
		if (imo == NULL || imo->imo_multicast_ifp == NULL)
			addr.s_addr = INADDR_ANY;
		else if (imo->imo_multicast_addr.s_addr) {
			/* return the value user has set */
			addr = imo->imo_multicast_addr;
		} else {
			IFP_TO_IA(imo->imo_multicast_ifp, ia);
			addr.s_addr = (ia == NULL) ? INADDR_ANY
				: IA_SIN(ia)->sin_addr.s_addr;
		}
		error = sooptcopyout(sopt, &addr, sizeof addr);
		break;

	case IP_MULTICAST_TTL:
		if (imo == 0)
			optval = coptval = IP_DEFAULT_MULTICAST_TTL;
		else
			optval = coptval = imo->imo_multicast_ttl;
		if (sopt->sopt_valsize == 1)
			error = sooptcopyout(sopt, &coptval, 1);
		else
			error = sooptcopyout(sopt, &optval, sizeof optval);
		break;

	case IP_MULTICAST_LOOP:
		if (imo == 0)
			optval = coptval = IP_DEFAULT_MULTICAST_LOOP;
		else
			optval = coptval = imo->imo_multicast_loop;
		if (sopt->sopt_valsize == 1)
			error = sooptcopyout(sopt, &coptval, 1);
		else
			error = sooptcopyout(sopt, &optval, sizeof optval);
		break;

	default:
		error = ENOPROTOOPT;
		break;
	}
	return (error);
}

/*
 * Discard the IP multicast options.
 */
void
ip_freemoptions(imo)
	register struct ip_moptions *imo;
{
	register int i;

	if (imo != NULL) {
		for (i = 0; i < imo->imo_num_memberships; ++i)
			in_delmulti(imo->imo_membership[i]);
		free(imo, M_IPMOPTS);
	}
}

/*
 * Routine called from ip_output() to loop back a copy of an IP multicast
 * packet to the input queue of a specified interface.  Note that this
 * calls the output routine of the loopback "driver", but with an interface
 * pointer that might NOT be a loopback interface -- evil, but easier than
 * replicating that code here.
 */
static void
ip_mloopback(ifp, m, dst, hlen)
	struct ifnet *ifp;
	register struct mbuf *m;
	register struct sockaddr_in *dst;
	int hlen;
{
	register struct ip *ip;
	struct mbuf *copym;

	copym = m_copy(m, 0, M_COPYALL);
	if (copym != NULL && (copym->m_flags & M_EXT || copym->m_len < hlen))
		copym = m_pullup(copym, hlen);
	if (copym != NULL) {
		/*
		 * We don't bother to fragment if the IP length is greater
		 * than the interface's MTU.  Can this possibly matter?
		 */
		ip = mtod(copym, struct ip *);
		HTONS(ip->ip_len);
		HTONS(ip->ip_off);
		ip->ip_sum = 0;
		if (ip->ip_vhl == IP_VHL_BORING) {
			ip->ip_sum = in_cksum_hdr(ip);
		} else {
			ip->ip_sum = in_cksum(copym, hlen);
		}
		/*
		 * NB:
		 * It's not clear whether there are any lingering
		 * reentrancy problems in other areas which might
		 * be exposed by using ip_input directly (in
		 * particular, everything which modifies the packet
		 * in-place).  Yet another option is using the
		 * protosw directly to deliver the looped back
		 * packet.  For the moment, we'll err on the side
		 * of safety by using if_simloop().
		 */
#if 1 /* XXX */
		if (dst->sin_family != AF_INET) {
			printf("ip_mloopback: bad address family %d\n",
						dst->sin_family);
			dst->sin_family = AF_INET;
		}
#endif

#ifdef notdef
		copym->m_pkthdr.rcvif = ifp;
		ip_input(copym);
#else
		/* if the checksum hasn't been computed, mark it as valid */
		if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
			copym->m_pkthdr.csum_flags |=
			    CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
			copym->m_pkthdr.csum_data = 0xffff;
		}
		if_simloop(ifp, copym, dst->sin_family, 0);
#endif
	}
}