socket.c

在linux环境下的流控制传输协议（sctp）的源代码

}

/* Add a list of addresses as bind addresses to local endpoint or
 * association.
 *
 * Basically run through each address specified in the addrs/addrcnt
 * array/length pair, determine if it is IPv6 or IPv4 and call
 * sctp_do_bind() on it.
 *
 * If any of them fails, then the operation will be reversed and the
 * ones that were added will be removed.
 *
 * Only sctp_setsockopt_bindx() is supposed to call this function.
 */
static int sctp_bindx_add(struct sock *sk, struct sockaddr *addrs, int addrcnt)
{
	int cnt;
	int retval = 0;
	void *addr_buf;
	struct sockaddr *sa_addr;
	struct sctp_af *af;

	SCTP_DEBUG_PRINTK("sctp_bindx_add (sk: %p, addrs: %p, addrcnt: %d)\n",
			  sk, addrs, addrcnt);

	addr_buf = addrs;
	for (cnt = 0; cnt < addrcnt; cnt++) {
		/* The list may contain either IPv4 or IPv6 address;
		 * determine the address length for walking thru the list.
		 */
		sa_addr = (struct sockaddr *)addr_buf;
		af = sctp_get_af_specific(sa_addr->sa_family);
		if (!af) {
			retval = -EINVAL;
			goto err_bindx_add;
		}

		retval = sctp_do_bind(sk, (union sctp_addr *)sa_addr,
				      af->sockaddr_len);

		addr_buf += af->sockaddr_len;

err_bindx_add:
		if (retval < 0) {
			/* Failed. Cleanup the ones that have been added */
			if (cnt > 0)
				sctp_bindx_rem(sk, addrs, cnt);
			return retval;
		}
	}

	return retval;
}

/* Send an ASCONF chunk with Add IP address parameters to all the peers of the
 * associations that are part of the endpoint indicating that a list of local
 * addresses are added to the endpoint.
 *
 * If any of the addresses is already in the bind address list of the
 * association, we do not send the chunk for that association.  But it will not
 * affect other associations.
 *
 * Only sctp_setsockopt_bindx() is supposed to call this function.
 */
static int sctp_send_asconf_add_ip(struct sock		*sk,
				   struct sockaddr	*addrs,
				   int 			addrcnt)
{
	struct sctp_sock		*sp;
	struct sctp_endpoint		*ep;
	struct sctp_association		*asoc;
	struct sctp_bind_addr		*bp;
	struct sctp_chunk		*chunk;
	struct sctp_sockaddr_entry	*laddr;
	union sctp_addr			*addr;
	union sctp_addr			saveaddr;
	void				*addr_buf;
	struct sctp_af			*af;
	struct list_head		*pos;
	struct list_head		*p;
	int 				i;
	int 				retval = 0;

	if (!sctp_addip_enable)
		return retval;

	sp = sctp_sk(sk);
	ep = sp->ep;

	SCTP_DEBUG_PRINTK("%s: (sk: %p, addrs: %p, addrcnt: %d)\n",
			  __FUNCTION__, sk, addrs, addrcnt);

	list_for_each(pos, &ep->asocs) {
		asoc = list_entry(pos, struct sctp_association, asocs);

		if (!asoc->peer.asconf_capable)
			continue;

		if (asoc->peer.addip_disabled_mask & SCTP_PARAM_ADD_IP)
			continue;

		if (!sctp_state(asoc, ESTABLISHED))
			continue;

		/* Check if any address in the packed array of addresses is
		 * in the bind address list of the association. If so,
		 * do not send the asconf chunk to its peer, but continue with
		 * other associations.
		 */
		addr_buf = addrs;
		for (i = 0; i < addrcnt; i++) {
			addr = (union sctp_addr *)addr_buf;
			af = sctp_get_af_specific(addr->v4.sin_family);
			if (!af) {
				retval = -EINVAL;
				goto out;
			}

			if (sctp_assoc_lookup_laddr(asoc, addr))
				break;

			addr_buf += af->sockaddr_len;
		}
		if (i < addrcnt)
			continue;

		/* Use the first valid address in bind addr list of
		 * association as Address Parameter of ASCONF CHUNK.
		 */
		bp = &asoc->base.bind_addr;
		p = bp->address_list.next;
		laddr = list_entry(p, struct sctp_sockaddr_entry, list);
		chunk = sctp_make_asconf_update_ip(asoc, &laddr->a, addrs,
						   addrcnt, SCTP_PARAM_ADD_IP);
		if (!chunk) {
			retval = -ENOMEM;
			goto out;
		}

		retval = sctp_send_asconf(asoc, chunk);
		if (retval)
			goto out;

		/* Add the new addresses to the bind address list with
		 * use_as_src set to 0.
		 */
		addr_buf = addrs;
		for (i = 0; i < addrcnt; i++) {
			addr = (union sctp_addr *)addr_buf;
			af = sctp_get_af_specific(addr->v4.sin_family);
			memcpy(&saveaddr, addr, af->sockaddr_len);
			retval = sctp_add_bind_addr(bp, &saveaddr,
						    SCTP_ADDR_NEW, GFP_ATOMIC);
			addr_buf += af->sockaddr_len;
		}
	}

out:
	return retval;
}

/* Remove a list of addresses from bind addresses list.  Do not remove the
 * last address.
 *
 * Basically run through each address specified in the addrs/addrcnt
 * array/length pair, determine if it is IPv6 or IPv4 and call
 * sctp_del_bind() on it.
 *
 * If any of them fails, then the operation will be reversed and the
 * ones that were removed will be added back.
 *
 * At least one address has to be left; if only one address is
 * available, the operation will return -EBUSY.
 *
 * Only sctp_setsockopt_bindx() is supposed to call this function.
 */
static int sctp_bindx_rem(struct sock *sk, struct sockaddr *addrs, int addrcnt)
{
	struct sctp_sock *sp = sctp_sk(sk);
	struct sctp_endpoint *ep = sp->ep;
	int cnt;
	struct sctp_bind_addr *bp = &ep->base.bind_addr;
	int retval = 0;
	void *addr_buf;
	union sctp_addr *sa_addr;
	struct sctp_af *af;

	SCTP_DEBUG_PRINTK("sctp_bindx_rem (sk: %p, addrs: %p, addrcnt: %d)\n",
			  sk, addrs, addrcnt);

	addr_buf = addrs;
	for (cnt = 0; cnt < addrcnt; cnt++) {
		/* If the bind address list is empty or if there is only one
		 * bind address, there is nothing more to be removed (we need
		 * at least one address here).
		 */
		if (list_empty(&bp->address_list) ||
		    (sctp_list_single_entry(&bp->address_list))) {
			retval = -EBUSY;
			goto err_bindx_rem;
		}

		sa_addr = (union sctp_addr *)addr_buf;
		af = sctp_get_af_specific(sa_addr->sa.sa_family);
		if (!af) {
			retval = -EINVAL;
			goto err_bindx_rem;
		}

		if (!af->addr_valid(sa_addr, sp, NULL)) {
			retval = -EADDRNOTAVAIL;
			goto err_bindx_rem;
		}

		if (sa_addr->v4.sin_port != htons(bp->port)) {
			retval = -EINVAL;
			goto err_bindx_rem;
		}

		/* FIXME - There is probably a need to check if sk->sk_saddr and
		 * sk->sk_rcv_addr are currently set to one of the addresses to
		 * be removed. This is something which needs to be looked into
		 * when we are fixing the outstanding issues with multi-homing
		 * socket routing and failover schemes. Refer to comments in
		 * sctp_do_bind(). -daisy
		 */
		retval = sctp_del_bind_addr(bp, sa_addr);

		addr_buf += af->sockaddr_len;
err_bindx_rem:
		if (retval < 0) {
			/* Failed. Add the ones that has been removed back */
			if (cnt > 0)
				sctp_bindx_add(sk, addrs, cnt);
			return retval;
		}
	}

	return retval;
}

/* Send an ASCONF chunk with Delete IP address parameters to all the peers of
 * the associations that are part of the endpoint indicating that a list of
 * local addresses are removed from the endpoint.
 *
 * If any of the addresses is already in the bind address list of the
 * association, we do not send the chunk for that association.  But it will not
 * affect other associations.
 *
 * Only sctp_setsockopt_bindx() is supposed to call this function.
 */
static int sctp_send_asconf_del_ip(struct sock		*sk,
				   struct sockaddr	*addrs,
				   int			addrcnt)
{
	struct sctp_sock	*sp;
	struct sctp_endpoint	*ep;
	struct sctp_association	*asoc;
	struct sctp_transport	*transport;
	struct sctp_bind_addr	*bp;
	struct sctp_chunk	*chunk;
	union sctp_addr		*laddr;
	void			*addr_buf;
	struct sctp_af		*af;
	struct list_head	*pos, *pos1;
	struct sctp_sockaddr_entry *saddr;
	int 			i;
	int 			retval = 0;

	if (!sctp_addip_enable)
		return retval;

	sp = sctp_sk(sk);
	ep = sp->ep;

	SCTP_DEBUG_PRINTK("%s: (sk: %p, addrs: %p, addrcnt: %d)\n",
			  __FUNCTION__, sk, addrs, addrcnt);

	list_for_each(pos, &ep->asocs) {
		asoc = list_entry(pos, struct sctp_association, asocs);

		if (!asoc->peer.asconf_capable)
			continue;

		if (asoc->peer.addip_disabled_mask & SCTP_PARAM_DEL_IP)
			continue;

		if (!sctp_state(asoc, ESTABLISHED))
			continue;

		/* Check if any address in the packed array of addresses is
		 * not present in the bind address list of the association.
		 * If so, do not send the asconf chunk to its peer, but
		 * continue with other associations.
		 */
		addr_buf = addrs;
		for (i = 0; i < addrcnt; i++) {
			laddr = (union sctp_addr *)addr_buf;
			af = sctp_get_af_specific(laddr->v4.sin_family);
			if (!af) {
				retval = -EINVAL;
				goto out;
			}

			if (!sctp_assoc_lookup_laddr(asoc, laddr))
				break;

			addr_buf += af->sockaddr_len;
		}
		if (i < addrcnt)
			continue;

		/* Find one address in the association's bind address list
		 * that is not in the packed array of addresses. This is to
		 * make sure that we do not delete all the addresses in the
		 * association.
		 */
		bp = &asoc->base.bind_addr;
		laddr = sctp_find_unmatch_addr(bp, (union sctp_addr *)addrs,
					       addrcnt, sp);
		if (!laddr)
			continue;

		/* We do not need RCU protection throughout this loop
		 * because this is done under a socket lock from the
		 * setsockopt call.
		 */
		chunk = sctp_make_asconf_update_ip(asoc, laddr, addrs, addrcnt,
						   SCTP_PARAM_DEL_IP);
		if (!chunk) {
			retval = -ENOMEM;
			goto out;
		}

		/* Reset use_as_src flag for the addresses in the bind address
		 * list that are to be deleted.
		 */
		addr_buf = addrs;
		for (i = 0; i < addrcnt; i++) {
			laddr = (union sctp_addr *)addr_buf;
			af = sctp_get_af_specific(laddr->v4.sin_family);
			list_for_each_entry(saddr, &bp->address_list, list) {
				if (sctp_cmp_addr_exact(&saddr->a, laddr))
					saddr->state = SCTP_ADDR_DEL;
			}
			addr_buf += af->sockaddr_len;
		}

		/* Update the route and saddr entries for all the transports
		 * as some of the addresses in the bind address list are
		 * about to be deleted and cannot be used as source addresses.
		 */
		list_for_each(pos1, &asoc->peer.transport_addr_list) {
			transport = list_entry(pos1, struct sctp_transport,
					       transports);
			dst_release(transport->dst);
			sctp_transport_route(transport, NULL,
					     sctp_sk(asoc->base.sk));
		}

		retval = sctp_send_asconf(asoc, chunk);
	}
out:
	return retval;
}

/* Helper for tunneling sctp_bindx() requests through sctp_setsockopt()
 *
 * API 8.1
 * int sctp_bindx(int sd, struct sockaddr *addrs, int addrcnt,
 *                int flags);
 *
 * If sd is an IPv4 socket, the addresses passed must be IPv4 addresses.
 * If the sd is an IPv6 socket, the addresses passed can either be IPv4
 * or IPv6 addresses.
 *
 * A single address may be specified as INADDR_ANY or IN6ADDR_ANY, see
 * Section 3.1.2 for this usage.
 *
 * addrs is a pointer to an array of one or more socket addresses. Each
 * address is contained in its appropriate structure (i.e. struct
 * sockaddr_in or struct sockaddr_in6) the family of the address type
 * must be used to distinguish the address length (note that this
 * representation is termed a "packed array" of addresses). The caller
 * specifies the number of addresses in the array with addrcnt.
 *
 * On success, sctp_bindx() returns 0. On failure, sctp_bindx() returns
 * -1, and sets errno to the appropriate error code.
 *
 * For SCTP, the port given in each socket address must be the same, or
 * sctp_bindx() will fail, setting errno to EINVAL.
 *
 * The flags parameter is formed from the bitwise OR of zero or more of
 * the following currently defined flags:
 *
 * SCTP_BINDX_ADD_ADDR
 *
 * SCTP_BINDX_REM_ADDR
 *
 * SCTP_BINDX_ADD_ADDR directs SCTP to add the given addresses to the
 * association, and SCTP_BINDX_REM_ADDR directs SCTP to remove the given
 * addresses from the association. The two flags are mutually exclusive;
 * if both are given, sctp_bindx() will fail with EINVAL. A caller may
 * not remove all addresses from an association; sctp_bindx() will
 * reject such an attempt with EINVAL.
 *
 * An application can use sctp_bindx(SCTP_BINDX_ADD_ADDR) to associate
 * additional addresses with an endpoint after calling bind().  Or use
 * sctp_bindx(SCTP_BINDX_REM_ADDR) to remove some addresses a listening
 * socket is associated with so that no new association accepted will be
 * associated with those addresses. If the endpoint supports dynamic
 * address a SCTP_BINDX_REM_ADDR or SCTP_BINDX_ADD_ADDR may cause a
 * endpoint to send the appropriate message to the peer to change the
 * peers address lists.
 *
 * Adding and removing addresses from a connected association is
 * optional functionality. Implementations that do not support this
 * functionality should return EOPNOTSUPP.
 *
 * Basically do nothing but copying the addresses from user to kernel
 * land and invoking either sctp_bindx_add() or sctp_bindx_rem() on the sk.
 * This is used for tunneling the sctp_bindx() request through sctp_setsockopt()
 * from userspace.
 *
 * We don't use copy_from_user() for optimization: we first do the
 * sanity checks (buffer size -fast- and access check-healthy
 * pointer); if all of those succeed, then we can alloc the memory
 * (expensive operation) needed to copy the data to kernel. Then we do
 * the copying without checking the user space area
 * (__copy_from_user()).
 *
 * On exit there is no need to do sockfd_put(), sys_setsockopt() does
 * it.
 *
 * sk        The sk of the socket
 * addrs     The pointer to the addresses in user land
 * addrssize Size of the addrs buffer