socket.c

/* SCTP kernel reference Implementation
 * (C) Copyright IBM Corp. 2001, 2004
 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001-2003 Intel Corp.
 * Copyright (c) 2001-2002 Nokia, Inc.
 * Copyright (c) 2001 La Monte H.P. Yarroll
 *
 * This file is part of the SCTP kernel reference Implementation
 *
 * These functions interface with the sockets layer to implement the
 * SCTP Extensions for the Sockets API.
 *
 * Note that the descriptions from the specification are USER level
 * functions--this file is the functions which populate the struct proto
 * for SCTP which is the BOTTOM of the sockets interface.
 *
 * The SCTP reference implementation is free software;
 * you can redistribute it and/or modify it under the terms of
 * the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * The SCTP reference implementation is distributed in the hope that it
 * will be useful, but WITHOUT ANY WARRANTY; without even the implied
 *                 ************************
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with GNU CC; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <lksctp-developers@lists.sourceforge.net>
 *
 * Or submit a bug report through the following website:
 *    http://www.sf.net/projects/lksctp
 *
 * Written or modified by:
 *    La Monte H.P. Yarroll <piggy@acm.org>
 *    Narasimha Budihal     <narsi@refcode.org>
 *    Karl Knutson          <karl@athena.chicago.il.us>
 *    Jon Grimm             <jgrimm@us.ibm.com>
 *    Xingang Guo           <xingang.guo@intel.com>
 *    Daisy Chang           <daisyc@us.ibm.com>
 *    Sridhar Samudrala     <samudrala@us.ibm.com>
 *    Inaky Perez-Gonzalez  <inaky.gonzalez@intel.com>
 *    Ardelle Fan	    <ardelle.fan@intel.com>
 *    Ryan Layer	    <rmlayer@us.ibm.com>
 *    Anup Pemmaiah         <pemmaiah@cc.usu.edu>
 *    Kevin Gao             <kevin.gao@intel.com>
 *
 * Any bugs reported given to us we will try to fix... any fixes shared will
 * be incorporated into the next SCTP release.
 */

#include <linux/config.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/wait.h>
#include <linux/time.h>
#include <linux/ip.h>
#include <linux/fcntl.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/crypto.h>

#include <net/ip.h>
#include <net/icmp.h>
#include <net/route.h>
#include <net/ipv6.h>
#include <net/inet_common.h>

#include <linux/socket.h> /* for sa_family_t */
#include <net/sock.h>
#include <net/sctp/sctp.h>
#include <net/sctp/sm.h>

/* WARNING:  Please do not remove the SCTP_STATIC attribute to
 * any of the functions below as they are used to export functions
 * used by a project regression testsuite.
 */

/* Forward declarations for internal helper functions. */
static int sctp_writeable(struct sock *sk);
static void sctp_wfree(struct sk_buff *skb);
static int sctp_wait_for_sndbuf(struct sctp_association *, long *timeo_p,
				size_t msg_len);
static int sctp_wait_for_packet(struct sock * sk, int *err, long *timeo_p);
static int sctp_wait_for_connect(struct sctp_association *, long *timeo_p);
static int sctp_wait_for_accept(struct sock *sk, long timeo);
static void sctp_wait_for_close(struct sock *sk, long timeo);
static struct sctp_af *sctp_sockaddr_af(struct sctp_sock *opt,
					union sctp_addr *addr, int len);
static int sctp_bindx_add(struct sock *, struct sockaddr *, int);
static int sctp_bindx_rem(struct sock *, struct sockaddr *, int);
static int sctp_send_asconf_add_ip(struct sock *, struct sockaddr *, int);
static int sctp_send_asconf_del_ip(struct sock *, struct sockaddr *, int);
static int sctp_send_asconf(struct sctp_association *asoc,
			    struct sctp_chunk *chunk);
static int sctp_do_bind(struct sock *, union sctp_addr *, int);
static int sctp_autobind(struct sock *sk);
static void sctp_sock_migrate(struct sock *, struct sock *,
			      struct sctp_association *, sctp_socket_type_t);
static char *sctp_hmac_alg = SCTP_COOKIE_HMAC_ALG;

extern kmem_cache_t *sctp_bucket_cachep;

/* Get the sndbuf space available at the time on the association.  */
static inline int sctp_wspace(struct sctp_association *asoc)
{
	struct sock *sk = asoc->base.sk;
	int amt = 0;

	if (asoc->ep->sndbuf_policy) {
		/* make sure that no association uses more than sk_sndbuf */
		amt = sk->sk_sndbuf - asoc->sndbuf_used;
	} else {
		/* do socket level accounting */
		amt = sk->sk_sndbuf - atomic_read(&sk->sk_wmem_alloc);
	}

	if (amt < 0)
		amt = 0;

	return amt;
}

/* Increment the used sndbuf space count of the corresponding association by
 * the size of the outgoing data chunk.
 * Also, set the skb destructor for sndbuf accounting later.
 *
 * Since it is always 1-1 between chunk and skb, and also a new skb is always
 * allocated for chunk bundling in sctp_packet_transmit(), we can use the
 * destructor in the data chunk skb for the purpose of the sndbuf space
 * tracking.
 */
static inline void sctp_set_owner_w(struct sctp_chunk *chunk)
{
	struct sctp_association *asoc = chunk->asoc;
	struct sock *sk = asoc->base.sk;

	/* The sndbuf space is tracked per association.  */
	sctp_association_hold(asoc);

	skb_set_owner_w(chunk->skb, sk);

	chunk->skb->destructor = sctp_wfree;
	/* Save the chunk pointer in skb for sctp_wfree to use later.  */
	*((struct sctp_chunk **)(chunk->skb->cb)) = chunk;

	asoc->sndbuf_used += SCTP_DATA_SNDSIZE(chunk) +
				sizeof(struct sk_buff) +
				sizeof(struct sctp_chunk);

	sk->sk_wmem_queued += SCTP_DATA_SNDSIZE(chunk) +
				sizeof(struct sk_buff) +
				sizeof(struct sctp_chunk);

	atomic_add(sizeof(struct sctp_chunk), &sk->sk_wmem_alloc);
}

/* Verify that this is a valid address. */
static inline int sctp_verify_addr(struct sock *sk, union sctp_addr *addr,
				   int len)
{
	struct sctp_af *af;

	/* Verify basic sockaddr. */
	af = sctp_sockaddr_af(sctp_sk(sk), addr, len);
	if (!af)
		return -EINVAL;

	/* Is this a valid SCTP address?  */
	if (!af->addr_valid(addr, sctp_sk(sk)))
		return -EINVAL;

	if (!sctp_sk(sk)->pf->send_verify(sctp_sk(sk), (addr)))
		return -EINVAL;

	return 0;
}

/* Look up the association by its id.  If this is not a UDP-style
 * socket, the ID field is always ignored.
 */
struct sctp_association *sctp_id2assoc(struct sock *sk, sctp_assoc_t id)
{
	struct sctp_association *asoc = NULL;

	/* If this is not a UDP-style socket, assoc id should be ignored. */
	if (!sctp_style(sk, UDP)) {
		/* Return NULL if the socket state is not ESTABLISHED. It
		 * could be a TCP-style listening socket or a socket which
		 * hasn't yet called connect() to establish an association.
		 */
		if (!sctp_sstate(sk, ESTABLISHED))
			return NULL;

		/* Get the first and the only association from the list. */
		if (!list_empty(&sctp_sk(sk)->ep->asocs))
			asoc = list_entry(sctp_sk(sk)->ep->asocs.next,
					  struct sctp_association, asocs);
		return asoc;
	}

	/* Otherwise this is a UDP-style socket. */
	if (!id || (id == (sctp_assoc_t)-1))
		return NULL;

	spin_lock_bh(&sctp_assocs_id_lock);
	asoc = (struct sctp_association *)idr_find(&sctp_assocs_id, (int)id);
	spin_unlock_bh(&sctp_assocs_id_lock);

	if (!asoc || (asoc->base.sk != sk) || asoc->base.dead)
		return NULL;

	return asoc;
}

/* Look up the transport from an address and an assoc id. If both address and
 * id are specified, the associations matching the address and the id should be
 * the same.
 */
static struct sctp_transport *sctp_addr_id2transport(struct sock *sk,
					      struct sockaddr_storage *addr,
					      sctp_assoc_t id)
{
	struct sctp_association *addr_asoc = NULL, *id_asoc = NULL;
	struct sctp_transport *transport;
	union sctp_addr *laddr = (union sctp_addr *)addr;

	laddr->v4.sin_port = ntohs(laddr->v4.sin_port);
	addr_asoc = sctp_endpoint_lookup_assoc(sctp_sk(sk)->ep,
					       (union sctp_addr *)addr,
					       &transport);
	laddr->v4.sin_port = htons(laddr->v4.sin_port);

	if (!addr_asoc)
		return NULL;

	id_asoc = sctp_id2assoc(sk, id);
	if (id_asoc && (id_asoc != addr_asoc))
		return NULL;

	sctp_get_pf_specific(sk->sk_family)->addr_v4map(sctp_sk(sk),
						(union sctp_addr *)addr);

	return transport;
}

/* API 3.1.2 bind() - UDP Style Syntax
 * The syntax of bind() is,
 *
 *   ret = bind(int sd, struct sockaddr *addr, int addrlen);
 *
 *   sd      - the socket descriptor returned by socket().
 *   addr    - the address structure (struct sockaddr_in or struct
 *             sockaddr_in6 [RFC 2553]),
 *   addr_len - the size of the address structure.
 */
SCTP_STATIC int sctp_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
{
	int retval = 0;

	sctp_lock_sock(sk);

	SCTP_DEBUG_PRINTK("sctp_bind(sk: %p, uaddr: %p, addr_len: %d)\n",
			  sk, uaddr, addr_len);

	/* Disallow binding twice. */
	if (!sctp_sk(sk)->ep->base.bind_addr.port)
		retval = sctp_do_bind(sk, (union sctp_addr *)uaddr,
				      addr_len);
	else
		retval = -EINVAL;

	sctp_release_sock(sk);

	return retval;
}

static long sctp_get_port_local(struct sock *, union sctp_addr *);

/* Verify this is a valid sockaddr. */
static struct sctp_af *sctp_sockaddr_af(struct sctp_sock *opt,
					union sctp_addr *addr, int len)
{
	struct sctp_af *af;

	/* Check minimum size.  */
	if (len < sizeof (struct sockaddr))
		return NULL;

	/* Does this PF support this AF? */
	if (!opt->pf->af_supported(addr->sa.sa_family, opt))
		return NULL;

	/* If we get this far, af is valid. */
	af = sctp_get_af_specific(addr->sa.sa_family);

	if (len < af->sockaddr_len)
		return NULL;

	return af;
}

/* Bind a local address either to an endpoint or to an association.  */
SCTP_STATIC int sctp_do_bind(struct sock *sk, union sctp_addr *addr, int len)
{
	struct sctp_sock *sp = sctp_sk(sk);
	struct sctp_endpoint *ep = sp->ep;
	struct sctp_bind_addr *bp = &ep->base.bind_addr;
	struct sctp_af *af;
	unsigned short snum;
	int ret = 0;

	SCTP_DEBUG_PRINTK("sctp_do_bind(sk: %p, newaddr: %p, len: %d)\n",
			  sk, addr, len);

	/* Common sockaddr verification. */
	af = sctp_sockaddr_af(sp, addr, len);
	if (!af)
		return -EINVAL;

	/* PF specific bind() address verification. */
	if (!sp->pf->bind_verify(sp, addr))
		return -EADDRNOTAVAIL;

	snum= ntohs(addr->v4.sin_port);

	SCTP_DEBUG_PRINTK("sctp_do_bind: port: %d, new port: %d\n",
			  bp->port, snum);

	/* We must either be unbound, or bind to the same port.  */
	if (bp->port && (snum != bp->port)) {
		SCTP_DEBUG_PRINTK("sctp_do_bind:"
				  " New port %d does not match existing port "
				  "%d.\n", snum, bp->port);
		return -EINVAL;
	}

	if (snum && snum < PROT_SOCK && !capable(CAP_NET_BIND_SERVICE))
		return -EACCES;

	/* Make sure we are allowed to bind here.
	 * The function sctp_get_port_local() does duplicate address
	 * detection.
	 */
	if ((ret = sctp_get_port_local(sk, addr))) {
		if (ret == (long) sk) {
			/* This endpoint has a conflicting address. */
			return -EINVAL;
		} else {
			return -EADDRINUSE;
		}
	}

	/* Refresh ephemeral port.  */
	if (!bp->port)
		bp->port = inet_sk(sk)->num;

	/* Add the address to the bind address list.  */
	sctp_local_bh_disable();
	sctp_write_lock(&ep->base.addr_lock);

	/* Use GFP_ATOMIC since BHs are disabled.  */
	addr->v4.sin_port = ntohs(addr->v4.sin_port);
	ret = sctp_add_bind_addr(bp, addr, GFP_ATOMIC);
	addr->v4.sin_port = htons(addr->v4.sin_port);
	sctp_write_unlock(&ep->base.addr_lock);
	sctp_local_bh_enable();

	/* Copy back into socket for getsockname() use. */
	if (!ret) {
		inet_sk(sk)->sport = htons(inet_sk(sk)->num);
		af->to_sk_saddr(addr, sk);
	}

	return ret;
}

 /* ADDIP Section 4.1.1 Congestion Control of ASCONF Chunks
 *
 * R1) One and only one ASCONF Chunk MAY be in transit and unacknowledged 
 * at any one time.  If a sender, after sending an ASCONF chunk, decides
 * it needs to transfer another ASCONF Chunk, it MUST wait until the 
 * ASCONF-ACK Chunk returns from the previous ASCONF Chunk before sending a
 * subsequent ASCONF. Note this restriction binds each side, so at any 
 * time two ASCONF may be in-transit on any given association (one sent 
 * from each endpoint).
 */
static int sctp_send_asconf(struct sctp_association *asoc,
			    struct sctp_chunk *chunk)
{
	int		retval = 0;

	/* If there is an outstanding ASCONF chunk, queue it for later
	 * transmission.
	 */	
	if (asoc->addip_last_asconf) {
		__skb_queue_tail(&asoc->addip_chunks, (struct sk_buff *)chunk);
		goto out;	
	}

	/* Hold the chunk until an ASCONF_ACK is received. */
	sctp_chunk_hold(chunk);
	retval = sctp_primitive_ASCONF(asoc, chunk);
	if (retval)
		sctp_chunk_free(chunk);
	else
		asoc->addip_last_asconf = chunk;

out:
	return retval;
}

/* 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.
 */
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;
	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 address in bind addr list of association as
		 * Address Parameter of ASCONF CHUNK.
		 */
		sctp_read_lock(&asoc->base.addr_lock);
		bp = &asoc->base.bind_addr;
		p = bp->address_list.next;
		laddr = list_entry(p, struct sctp_sockaddr_entry, list);
		sctp_read_unlock(&asoc->base.addr_lock);

		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);

		/* FIXME: After sending the add address ASCONF chunk, we
		 * cannot append the address to the association's binding
		 * address list, because the new address may be used as the
		 * source of a message sent to the peer before the ASCONF
		 * chunk is received by the peer.  So we should wait until
		 * ASCONF_ACK is received.
		 */
	}

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.
 */
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;
	union sctp_addr saveaddr;
	void *addr_buf;
	struct sockaddr *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;
		}

		/* The list may contain either IPv4 or IPv6 address;
		 * determine the address length to copy the address to
		 * saveaddr. 
		 */
		sa_addr = (struct sockaddr *)addr_buf;
		af = sctp_get_af_specific(sa_addr->sa_family);
		if (!af) {
			retval = -EINVAL;
			goto err_bindx_rem;
		}
		memcpy(&saveaddr, sa_addr, af->sockaddr_len); 
		saveaddr.v4.sin_port = ntohs(saveaddr.v4.sin_port);
		if (saveaddr.v4.sin_port != 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
		 */
		sctp_local_bh_disable();
		sctp_write_lock(&ep->base.addr_lock);

		retval = sctp_del_bind_addr(bp, &saveaddr);

		sctp_write_unlock(&ep->base.addr_lock);
		sctp_local_bh_enable();

		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_bind_addr	*bp;
	struct sctp_chunk	*chunk;
	union sctp_addr		*laddr;
	void			*addr_buf;
	struct sctp_af		*af;
	struct list_head	*pos;
	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.
		 */
		sctp_read_lock(&asoc->base.addr_lock);
		bp = &asoc->base.bind_addr;
		laddr = sctp_find_unmatch_addr(bp, (union sctp_addr *)addrs,
					       addrcnt, sp);
		sctp_read_unlock(&asoc->base.addr_lock);
		if (!laddr)
			continue;

		chunk = sctp_make_asconf_update_ip(asoc, laddr, addrs, addrcnt,
						   SCTP_PARAM_DEL_IP);
		if (!chunk) {
			retval = -ENOMEM;
			goto out;
		}

		retval = sctp_send_asconf(asoc, chunk);

		/* FIXME: After sending the delete address ASCONF chunk, we
		 * cannot remove the addresses from the association's bind
		 * address list, because there maybe some packet send to
		 * the delete addresses, so we should wait until ASCONF_ACK
		 * packet is received.
		 */
	}
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 distengish 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
 * op        Operation to perform (add or remove, see the flags of
 *           sctp_bindx)
 *
 * Returns 0 if ok, <0 errno code on error.
 */
SCTP_STATIC int sctp_setsockopt_bindx(struct sock* sk,
				      struct sockaddr __user *addrs,
				      int addrs_size, int op)
{
	struct sockaddr *kaddrs;
	int err;
	int addrcnt = 0;
	int walk_size = 0;
	struct sockaddr *sa_addr;
	void *addr_buf;
	struct sctp_af *af;

	SCTP_DEBUG_PRINTK("sctp_setsocktopt_bindx: sk %p addrs %p"
			  " addrs_size %d opt %d\n", sk, addrs, addrs_size, op);

	if (unlikely(addrs_size <= 0))
		return -EINVAL;

	/* Check the user passed a healthy pointer.  */
	if (unlikely(!access_ok(VERIFY_READ, addrs, addrs_size)))
		return -EFAULT;

	/* Alloc space for the address array in kernel memory.  */
	kaddrs = (struct sockaddr *)kmalloc(addrs_size, GFP_KERNEL);
	if (unlikely(!kaddrs))
		return -ENOMEM;

	if (__copy_from_user(kaddrs, addrs, addrs_size)) {
		kfree(kaddrs);
		return -EFAULT;
	}

	/* Walk through the addrs buffer and count the number of addresses. */ 
	addr_buf = kaddrs;
	while (walk_size < addrs_size) {
		sa_addr = (struct sockaddr *)addr_buf;
		af = sctp_get_af_specific(sa_addr->sa_family);

		/* If the address family is not supported or if this address
		 * causes the address buffer to overflow return EINVAL.
		 */ 
		if (!af || (walk_size + af->sockaddr_len) > addrs_size) {
			kfree(kaddrs);
			return -EINVAL;
		}
		addrcnt++;
		addr_buf += af->sockaddr_len;
		walk_size += af->sockaddr_len;
	}

	/* Do the work. */
	switch (op) {
	case SCTP_BINDX_ADD_ADDR:
		err = sctp_bindx_add(sk, kaddrs, addrcnt);
		if (err)
			goto out;
		err = sctp_send_asconf_add_ip(sk, kaddrs, addrcnt);
		break;

	case SCTP_BINDX_REM_ADDR:
		err = sctp_bindx_rem(sk, kaddrs, addrcnt);
		if (err)
			goto out;
		err = sctp_send_asconf_del_ip(sk, kaddrs, addrcnt);
		break;

	default:
		err = -EINVAL;
		break;
        };

out:
	kfree(kaddrs);

	return err;
}

/* API 3.1.4 close() - UDP Style Syntax
 * Applications use close() to perform graceful shutdown (as described in
 * Section 10.1 of [SCTP]) on ALL the associations currently represented
 * by a UDP-style socket.
 *
 * The syntax is
 *
 *   ret = close(int sd);
 *
 *   sd      - the socket descriptor of the associations to be closed.
 *
 * To gracefully shutdown a specific association represented by the
 * UDP-style socket, an application should use the sendmsg() call,
 * passing no user data, but including the appropriate flag in the
 * ancillary data (see Section xxxx).
 *
 * If sd in the close() call is a branched-off socket representing only
 * one association, the shutdown is performed on that association only.
 *
 * 4.1.6 close() - TCP Style Syntax
 *
 * Applications use close() to gracefully close down an association.
 *
 * The syntax is:
 *
 *    int close(int sd);
 *
 *      sd      - the socket descriptor of the association to be closed.
 *
 * After an application calls close() on a socket descriptor, no further
 * socket operations will succeed on that descriptor.
 *
 * API 7.1.4 SO_LINGER
 *
 * An application using the TCP-style socket can use this option to
 * perform the SCTP ABORT primitive.  The linger option structure is:
 *
 *  struct  linger {
 *     int     l_onoff;                // option on/off
 *     int     l_linger;               // linger time
 * };
 *
 * To enable the option, set l_onoff to 1.  If the l_linger value is set
 * to 0, calling close() is the same as the ABORT primitive.  If the
 * value is set to a negative value, the setsockopt() call will return
 * an error.  If the value is set to a positive value linger_time, the
 * close() can be blocked for at most linger_time ms.  If the graceful
 * shutdown phase does not finish during this period, close() will
 * return but the graceful shutdown phase continues in the system.
 */
SCTP_STATIC void sctp_close(struct sock *sk, long timeout)
{
	struct sctp_endpoint *ep;
	struct sctp_association *asoc;
	struct list_head *pos, *temp;

	SCTP_DEBUG_PRINTK("sctp_close(sk: 0x%p, timeout:%ld)\n", sk, timeout);

	sctp_lock_sock(sk);
	sk->sk_shutdown = SHUTDOWN_MASK;

	ep = sctp_sk(sk)->ep;

	/* Walk all associations on a socket, not on an endpoint.  */
	list_for_each_safe(pos, temp, &ep->asocs) {
		asoc = list_entry(pos, struct sctp_association, asocs);

		if (sctp_style(sk, TCP)) {
			/* A closed association can still be in the list if
			 * it belongs to a TCP-style listening socket that is
			 * not yet accepted. If so, free it. If not, send an
			 * ABORT or SHUTDOWN based on the linger options.
			 */
			if (sctp_state(asoc, CLOSED)) {
				sctp_unhash_established(asoc);
				sctp_association_free(asoc);

			} else if (sock_flag(sk, SOCK_LINGER) &&
				   !sk->sk_lingertime)
				sctp_primitive_ABORT(asoc, NULL);
			else
				sctp_primitive_SHUTDOWN(asoc, NULL);
		} else
			sctp_primitive_SHUTDOWN(asoc, NULL);
	}