ftp://ftp.kernel.org/pub/linux/kernel/v2.6/linux-2.6.6.tar.bz2

[linux-2.6.git] / net / sctp / 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 inline int sctp_wspace(struct sctp_association *asoc);
static inline void sctp_set_owner_w(struct sctp_chunk *chunk);
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 inline int sctp_verify_addr(struct sock *, union sctp_addr *, int);
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;
extern int sctp_assoc_valid(struct sock *sk, struct sctp_association *asoc);

/* 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.
 */
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.
 */
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_opt *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_opt *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 (!snum)
                snum = 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);
        if (!ret && !bp->port)
                bp->port = snum;
        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_opt                 *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_opt *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_opt         *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 *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);
        }

        /* Clean up any skbs sitting on the receive queue.  */
        sctp_queue_purge_ulpevents(&sk->sk_receive_queue);
        sctp_queue_purge_ulpevents(&sctp_sk(sk)->pd_lobby);

        /* On a TCP-style socket, block for at most linger_time if set. */
        if (sctp_style(sk, TCP) && timeout)
                sctp_wait_for_close(sk, timeout);

        /* This will run the backlog queue.  */
        sctp_release_sock(sk);

        /* Supposedly, no process has access to the socket, but
         * the net layers still may.
         */
        sctp_local_bh_disable();
        sctp_bh_lock_sock(sk);

        /* Hold the sock, since inet_sock_release() will put sock_put()
         * and we have just a little more cleanup.
         */
        sock_hold(sk);
        inet_sock_release(sk);

        sctp_bh_unlock_sock(sk);
        sctp_local_bh_enable();

        sock_put(sk);

        SCTP_DBG_OBJCNT_DEC(sock);
}

/* Handle EPIPE error. */
static int sctp_error(struct sock *sk, int flags, int err)
{
        if (err == -EPIPE)
                err = sock_error(sk) ? : -EPIPE;
        if (err == -EPIPE && !(flags & MSG_NOSIGNAL))
                send_sig(SIGPIPE, current, 0);
        return err;
}

/* API 3.1.3 sendmsg() - UDP Style Syntax
 *
 * An application uses sendmsg() and recvmsg() calls to transmit data to
 * and receive data from its peer.
 *
 *  ssize_t sendmsg(int socket, const struct msghdr *message,
 *                  int flags);
 *
 *  socket  - the socket descriptor of the endpoint.
 *  message - pointer to the msghdr structure which contains a single
 *            user message and possibly some ancillary data.
 *
 *            See Section 5 for complete description of the data
 *            structures.
 *
 *  flags   - flags sent or received with the user message, see Section
 *            5 for complete description of the flags.
 *
 * Note:  This function could use a rewrite especially when explicit
 * connect support comes in.
 */
/* BUG:  We do not implement the equivalent of wait_for_tcp_memory(). */

SCTP_STATIC int sctp_msghdr_parse(const struct msghdr *, sctp_cmsgs_t *);

SCTP_STATIC int sctp_sendmsg(struct kiocb *iocb, struct sock *sk,
                             struct msghdr *msg, size_t msg_len)
{
        struct sctp_opt *sp;
        struct sctp_endpoint *ep;
        struct sctp_association *new_asoc=NULL, *asoc=NULL;
        struct sctp_transport *transport, *chunk_tp;
        struct sctp_chunk *chunk;
        union sctp_addr to;
        struct sockaddr *msg_name = NULL;
        struct sctp_sndrcvinfo default_sinfo = { 0 };
        struct sctp_sndrcvinfo *sinfo;
        struct sctp_initmsg *sinit;
        sctp_assoc_t associd = NULL;
        sctp_cmsgs_t cmsgs = { 0 };
        int err;
        sctp_scope_t scope;
        long timeo;
        __u16 sinfo_flags = 0;
        struct sctp_datamsg *datamsg;
        struct list_head *pos;
        int msg_flags = msg->msg_flags;

        SCTP_DEBUG_PRINTK("sctp_sendmsg(sk: %p, msg: %p, msg_len: %zu)\n",
                          sk, msg, msg_len);

        err = 0;
        sp = sctp_sk(sk);
        ep = sp->ep;

        SCTP_DEBUG_PRINTK("Using endpoint: %s.\n", ep->debug_name);

        /* We cannot send a message over a TCP-style listening socket. */
        if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING)) {
                err = -EPIPE;
                goto out_nounlock;
        }

        /* Parse out the SCTP CMSGs.  */
        err = sctp_msghdr_parse(msg, &cmsgs);

        if (err) {
                SCTP_DEBUG_PRINTK("msghdr parse err = %x\n", err);
                goto out_nounlock;
        }

        /* Fetch the destination address for this packet.  This
         * address only selects the association--it is not necessarily
         * the address we will send to.
         * For a peeled-off socket, msg_name is ignored.
         */
        if (!sctp_style(sk, UDP_HIGH_BANDWIDTH) && msg->msg_name) {
                int msg_namelen = msg->msg_namelen;

                err = sctp_verify_addr(sk, (union sctp_addr *)msg->msg_name,
                                       msg_namelen);
                if (err)
                        return err;

                if (msg_namelen > sizeof(to))
                        msg_namelen = sizeof(to);
                memcpy(&to, msg->msg_name, msg_namelen);
                SCTP_DEBUG_PRINTK("Just memcpy'd. msg_name is "
                                  "0x%x:%u.\n",
                                  to.v4.sin_addr.s_addr, to.v4.sin_port);

                to.v4.sin_port = ntohs(to.v4.sin_port);
                msg_name = msg->msg_name;
        }

        sinfo = cmsgs.info;
        sinit = cmsgs.init;

        /* Did the user specify SNDRCVINFO?  */
        if (sinfo) {
                sinfo_flags = sinfo->sinfo_flags;
                associd = sinfo->sinfo_assoc_id;
        }

        SCTP_DEBUG_PRINTK("msg_len: %zu, sinfo_flags: 0x%x\n",
                          msg_len, sinfo_flags);

        /* MSG_EOF or MSG_ABORT cannot be set on a TCP-style socket. */
        if (sctp_style(sk, TCP) && (sinfo_flags & (MSG_EOF | MSG_ABORT))) {
                err = -EINVAL;
                goto out_nounlock;
        }

        /* If MSG_EOF is set, no data can be sent. Disallow sending zero
         * length messages when MSG_EOF|MSG_ABORT is not set.
         * If MSG_ABORT is set, the message length could be non zero with
         * the msg_iov set to the user abort reason.
         */
        if (((sinfo_flags & MSG_EOF) && (msg_len > 0)) ||
            (!(sinfo_flags & (MSG_EOF|MSG_ABORT)) && (msg_len == 0))) {
                err = -EINVAL;
                goto out_nounlock;
        }

        /* If MSG_ADDR_OVER is set, there must be an address
         * specified in msg_name.
         */
        if ((sinfo_flags & MSG_ADDR_OVER) && (!msg->msg_name)) {
                err = -EINVAL;
                goto out_nounlock;
        }

        transport = NULL;

        SCTP_DEBUG_PRINTK("About to look up association.\n");

        sctp_lock_sock(sk);

        /* If a msg_name has been specified, assume this is to be used.  */
        if (msg_name) {
                /* Look for a matching association on the endpoint. */
                asoc = sctp_endpoint_lookup_assoc(ep, &to, &transport);
                if (!asoc) {
                        /* If we could not find a matching association on the
                         * endpoint, make sure that it is not a TCP-style
                         * socket that already has an association or there is
                         * no peeled-off association on another socket.
                         */
                        if ((sctp_style(sk, TCP) &&
                             sctp_sstate(sk, ESTABLISHED)) ||
                            sctp_endpoint_is_peeled_off(ep, &to)) {
                                err = -EADDRNOTAVAIL;
                                goto out_unlock;
                        }
                }
        } else {
                asoc = sctp_id2assoc(sk, associd);
                if (!asoc) {
                        err = -EPIPE;
                        goto out_unlock;
                }
        }

        if (asoc) {
                SCTP_DEBUG_PRINTK("Just looked up association: %p.\n", asoc);

                /* We cannot send a message on a TCP-style SCTP_SS_ESTABLISHED
                 * socket that has an association in CLOSED state. This can
                 * happen when an accepted socket has an association that is
                 * already CLOSED.
                 */
                if (sctp_state(asoc, CLOSED) && sctp_style(sk, TCP)) {
                        err = -EPIPE;
                        goto out_unlock;
                }

                if (sinfo_flags & MSG_EOF) {
                        SCTP_DEBUG_PRINTK("Shutting down association: %p\n",
                                          asoc);
                        sctp_primitive_SHUTDOWN(asoc, NULL);
                        err = 0;
                        goto out_unlock;
                }
                if (sinfo_flags & MSG_ABORT) {
                        SCTP_DEBUG_PRINTK("Aborting association: %p\n", asoc);
                        sctp_primitive_ABORT(asoc, msg);
                        err = 0;
                        goto out_unlock;
                }
        }

        /* Do we need to create the association?  */
        if (!asoc) {
                SCTP_DEBUG_PRINTK("There is no association yet.\n");

                /* Check for invalid stream against the stream counts,
                 * either the default or the user specified stream counts.
                 */
                if (sinfo) {
                        if (!sinit || (sinit && !sinit->sinit_num_ostreams)) {
                                /* Check against the defaults. */
                                if (sinfo->sinfo_stream >=
                                    sp->initmsg.sinit_num_ostreams) {
                                        err = -EINVAL;
                                        goto out_unlock;
                                }
                        } else {
                                /* Check against the requested.  */
                                if (sinfo->sinfo_stream >=
                                    sinit->sinit_num_ostreams) {
                                        err = -EINVAL;
                                        goto out_unlock;
                                }
                        }
                }

                /*
                 * API 3.1.2 bind() - UDP Style Syntax
                 * If a bind() or sctp_bindx() is not called prior to a
                 * sendmsg() call that initiates a new association, the
                 * system picks an ephemeral port and will choose an address
                 * set equivalent to binding with a wildcard address.
                 */
                if (!ep->base.bind_addr.port) {
                        if (sctp_autobind(sk)) {
                                err = -EAGAIN;
                                goto out_unlock;
                        }
                }

                scope = sctp_scope(&to);
                new_asoc = sctp_association_new(ep, sk, scope, GFP_KERNEL);
                if (!new_asoc) {
                        err = -ENOMEM;
                        goto out_unlock;
                }
                asoc = new_asoc;

                /* If the SCTP_INIT ancillary data is specified, set all
                 * the association init values accordingly.
                 */
                if (sinit) {
                        if (sinit->sinit_num_ostreams) {
                                asoc->c.sinit_num_ostreams =
                                        sinit->sinit_num_ostreams;
                        }
                        if (sinit->sinit_max_instreams) {
                                asoc->c.sinit_max_instreams =
                                        sinit->sinit_max_instreams;
                        }
                        if (sinit->sinit_max_attempts) {
                                asoc->max_init_attempts
                                        = sinit->sinit_max_attempts;
                        }
                        if (sinit->sinit_max_init_timeo) {
                                asoc->max_init_timeo = 
                                 MSECS_TO_JIFFIES(sinit->sinit_max_init_timeo);
                        }
                }

                /* Prime the peer's transport structures.  */
                transport = sctp_assoc_add_peer(asoc, &to, GFP_KERNEL);
                if (!transport) {
                        err = -ENOMEM;
                        goto out_free;
                }
                err = sctp_assoc_set_bind_addr_from_ep(asoc, GFP_KERNEL);
                if (err < 0) {
                        err = -ENOMEM;
                        goto out_free;
                }
        }

        /* ASSERT: we have a valid association at this point.  */
        SCTP_DEBUG_PRINTK("We have a valid association.\n");

        if (!sinfo) {
                /* If the user didn't specify SNDRCVINFO, make up one with
                 * some defaults.
                 */
                default_sinfo.sinfo_stream = asoc->default_stream;
                default_sinfo.sinfo_flags = asoc->default_flags;
                default_sinfo.sinfo_ppid = asoc->default_ppid;
                default_sinfo.sinfo_context = asoc->default_context;
                default_sinfo.sinfo_timetolive = asoc->default_timetolive;
                default_sinfo.sinfo_assoc_id = sctp_assoc2id(asoc);
                sinfo = &default_sinfo;
        }

        /* API 7.1.7, the sndbuf size per association bounds the
         * maximum size of data that can be sent in a single send call.
         */
        if (msg_len > sk->sk_sndbuf) {
                err = -EMSGSIZE;
                goto out_free;
        }

        /* If fragmentation is disabled and the message length exceeds the
         * association fragmentation point, return EMSGSIZE.  The I-D
         * does not specify what this error is, but this looks like
         * a great fit.
         */
        if (sctp_sk(sk)->disable_fragments && (msg_len > asoc->frag_point)) {
                err = -EMSGSIZE;
                goto out_free;
        }

        if (sinfo) {
                /* Check for invalid stream. */
                if (sinfo->sinfo_stream >= asoc->c.sinit_num_ostreams) {
                        err = -EINVAL;
                        goto out_free;
                }
        }

        timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
        if (!sctp_wspace(asoc)) {
                err = sctp_wait_for_sndbuf(asoc, &timeo, msg_len);
                if (err)
                        goto out_free;
        }

        /* If an address is passed with the sendto/sendmsg call, it is used
         * to override the primary destination address in the TCP model, or
         * when MSG_ADDR_OVER flag is set in the UDP model.
         */
        if ((sctp_style(sk, TCP) && msg_name) ||
            (sinfo_flags & MSG_ADDR_OVER)) {
                chunk_tp = sctp_assoc_lookup_paddr(asoc, &to);
                if (!chunk_tp) {
                        err = -EINVAL;
                        goto out_free;
                }
        } else
                chunk_tp = NULL;

        /* Auto-connect, if we aren't connected already. */
        if (sctp_state(asoc, CLOSED)) {
                err = sctp_primitive_ASSOCIATE(asoc, NULL);
                if (err < 0)
                        goto out_free;
                SCTP_DEBUG_PRINTK("We associated primitively.\n");
        }

        /* Break the message into multiple chunks of maximum size. */
        datamsg = sctp_datamsg_from_user(asoc, sinfo, msg, msg_len);
        if (!datamsg) {
                err = -ENOMEM;
                goto out_free;
        }

        /* Now send the (possibly) fragmented message. */
        list_for_each(pos, &datamsg->chunks) {
                chunk = list_entry(pos, struct sctp_chunk, frag_list);
                sctp_datamsg_track(chunk);

                /* Do accounting for the write space.  */
                sctp_set_owner_w(chunk);

                chunk->transport = chunk_tp;

                /* Send it to the lower layers.  Note:  all chunks
                 * must either fail or succeed.   The lower layer
                 * works that way today.  Keep it that way or this
                 * breaks.
                 */
                err = sctp_primitive_SEND(asoc, chunk);
                /* Did the lower layer accept the chunk? */
                if (err)
                        sctp_chunk_free(chunk);
                SCTP_DEBUG_PRINTK("We sent primitively.\n");
        }

        sctp_datamsg_free(datamsg);
        if (err)
                goto out_free;
        else
                err = msg_len;

        /* If we are already past ASSOCIATE, the lower
         * layers are responsible for association cleanup.
         */
        goto out_unlock;

out_free:
        if (new_asoc)
                sctp_association_free(asoc);
out_unlock:
        sctp_release_sock(sk);

out_nounlock:
        return sctp_error(sk, msg_flags, err);

#if 0
do_sock_err:
        if (msg_len)
                err = msg_len;
        else
                err = sock_error(sk);
        goto out;

do_interrupted:
        if (msg_len)
                err = msg_len;
        goto out;
#endif /* 0 */
}

/* This is an extended version of skb_pull() that removes the data from the
 * start of a skb even when data is spread across the list of skb's in the
 * frag_list. len specifies the total amount of data that needs to be removed.
 * when 'len' bytes could be removed from the skb, it returns 0.
 * If 'len' exceeds the total skb length,  it returns the no. of bytes that
 * could not be removed.
 */
static int sctp_skb_pull(struct sk_buff *skb, int len)
{
        struct sk_buff *list;
        int skb_len = skb_headlen(skb);
        int rlen;

        if (len <= skb_len) {
                __skb_pull(skb, len);
                return 0;
        }
        len -= skb_len;
        __skb_pull(skb, skb_len);

        for (list = skb_shinfo(skb)->frag_list; list; list = list->next) {
                rlen = sctp_skb_pull(list, len);
                skb->len -= (len-rlen);
                skb->data_len -= (len-rlen);

                if (!rlen)
                        return 0;

                len = rlen;
        }

        return len;
}

/* API 3.1.3  recvmsg() - UDP Style Syntax
 *
 *  ssize_t recvmsg(int socket, struct msghdr *message,
 *                    int flags);
 *
 *  socket  - the socket descriptor of the endpoint.
 *  message - pointer to the msghdr structure which contains a single
 *            user message and possibly some ancillary data.
 *
 *            See Section 5 for complete description of the data
 *            structures.
 *
 *  flags   - flags sent or received with the user message, see Section
 *            5 for complete description of the flags.
 */
static struct sk_buff *sctp_skb_recv_datagram(struct sock *, int, int, int *);

SCTP_STATIC int sctp_recvmsg(struct kiocb *iocb, struct sock *sk,
                             struct msghdr *msg, size_t len, int noblock,
                             int flags, int *addr_len)
{
        struct sctp_ulpevent *event = NULL;
        struct sctp_opt *sp = sctp_sk(sk);
        struct sk_buff *skb;
        int copied;
        int err = 0;
        int skb_len;

        SCTP_DEBUG_PRINTK("sctp_recvmsg(%s: %p, %s: %p, %s: %zd, %s: %d, %s: "
                          "0x%x, %s: %p)\n", "sk", sk, "msghdr", msg,
                          "len", len, "knoblauch", noblock,
                          "flags", flags, "addr_len", addr_len);

        sctp_lock_sock(sk);

        if (sctp_style(sk, TCP) && !sctp_sstate(sk, ESTABLISHED)) {
                err = -ENOTCONN;
                goto out;
        }

        skb = sctp_skb_recv_datagram(sk, flags, noblock, &err);
        if (!skb)
                goto out;

        /* Get the total length of the skb including any skb's in the
         * frag_list.
         */
        skb_len = skb->len;

        copied = skb_len;
        if (copied > len)
                copied = len;

        err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);

        event = sctp_skb2event(skb);

        if (err)
                goto out_free;

        sock_recv_timestamp(msg, sk, skb);
        if (sctp_ulpevent_is_notification(event)) {
                msg->msg_flags |= MSG_NOTIFICATION;
                sp->pf->event_msgname(event, msg->msg_name, addr_len);
        } else {
                sp->pf->skb_msgname(skb, msg->msg_name, addr_len);
        }

        /* Check if we allow SCTP_SNDRCVINFO. */
        if (sp->subscribe.sctp_data_io_event)
                sctp_ulpevent_read_sndrcvinfo(event, msg);
#if 0
        /* FIXME: we should be calling IP/IPv6 layers.  */
        if (sk->sk_protinfo.af_inet.cmsg_flags)
                ip_cmsg_recv(msg, skb);
#endif

        err = copied;

        /* If skb's length exceeds the user's buffer, update the skb and
         * push it back to the receive_queue so that the next call to
         * recvmsg() will return the remaining data. Don't set MSG_EOR.
         */
        if (skb_len > copied) {
                msg->msg_flags &= ~MSG_EOR;
                if (flags & MSG_PEEK)
                        goto out_free;
                sctp_skb_pull(skb, copied);
                skb_queue_head(&sk->sk_receive_queue, skb);

                /* When only partial message is copied to the user, increase
                 * rwnd by that amount. If all the data in the skb is read,
                 * rwnd is updated when the event is freed.
                 */
                sctp_assoc_rwnd_increase(event->asoc, copied);
                goto out;
        } else if ((event->msg_flags & MSG_NOTIFICATION) ||
                   (event->msg_flags & MSG_EOR))
                msg->msg_flags |= MSG_EOR;
        else
                msg->msg_flags &= ~MSG_EOR;

out_free:
        if (flags & MSG_PEEK) {
                /* Release the skb reference acquired after peeking the skb in
                 * sctp_skb_recv_datagram().
                 */
                kfree_skb(skb);
        } else {
                /* Free the event which includes releasing the reference to
                 * the owner of the skb, freeing the skb and updating the
                 * rwnd.
                 */
                sctp_ulpevent_free(event);
        }
out:
        sctp_release_sock(sk);
        return err;
}

/* 7.1.12 Enable/Disable message fragmentation (SCTP_DISABLE_FRAGMENTS)
 *
 * This option is a on/off flag.  If enabled no SCTP message
 * fragmentation will be performed.  Instead if a message being sent
 * exceeds the current PMTU size, the message will NOT be sent and
 * instead a error will be indicated to the user.
 */
static int sctp_setsockopt_disable_fragments(struct sock *sk,
                                                    char *optval, int optlen)
{
        int val;

        if (optlen < sizeof(int))
                return -EINVAL;

        if (get_user(val, (int *)optval))
                return -EFAULT;

        sctp_sk(sk)->disable_fragments = (val == 0) ? 0 : 1;

        return 0;
}

static int sctp_setsockopt_events(struct sock *sk, char *optval,
                                        int optlen)
{
        if (optlen != sizeof(struct sctp_event_subscribe))
                return -EINVAL;
        if (copy_from_user(&sctp_sk(sk)->subscribe, optval, optlen))
                return -EFAULT;
        return 0;
}

/* 7.1.8 Automatic Close of associations (SCTP_AUTOCLOSE)
 *
 * This socket option is applicable to the UDP-style socket only.  When
 * set it will cause associations that are idle for more than the
 * specified number of seconds to automatically close.  An association
 * being idle is defined an association that has NOT sent or received
 * user data.  The special value of '0' indicates that no automatic
 * close of any associations should be performed.  The option expects an
 * integer defining the number of seconds of idle time before an
 * association is closed.
 */
static int sctp_setsockopt_autoclose(struct sock *sk, char *optval,
                                            int optlen)
{
        struct sctp_opt *sp = sctp_sk(sk);

        /* Applicable to UDP-style socket only */
        if (sctp_style(sk, TCP))
                return -EOPNOTSUPP;
        if (optlen != sizeof(int))
                return -EINVAL;
        if (copy_from_user(&sp->autoclose, optval, optlen))
                return -EFAULT;

        sp->ep->timeouts[SCTP_EVENT_TIMEOUT_AUTOCLOSE] = sp->autoclose * HZ;
        return 0;
}

/* 7.1.13 Peer Address Parameters (SCTP_PEER_ADDR_PARAMS)
 *
 * Applications can enable or disable heartbeats for any peer address of
 * an association, modify an address's heartbeat interval, force a
 * heartbeat to be sent immediately, and adjust the address's maximum
 * number of retransmissions sent before an address is considered
 * unreachable.  The following structure is used to access and modify an
 * address's parameters:
 *
 *  struct sctp_paddrparams {
 *      sctp_assoc_t            spp_assoc_id;
 *      struct sockaddr_storage spp_address;
 *      uint32_t                spp_hbinterval;
 *      uint16_t                spp_pathmaxrxt;
 *  };
 *
 *   spp_assoc_id    - (UDP style socket) This is filled in the application,
 *                     and identifies the association for this query.
 *   spp_address     - This specifies which address is of interest.
 *   spp_hbinterval  - This contains the value of the heartbeat interval,
 *                     in milliseconds.  A value of 0, when modifying the
 *                     parameter, specifies that the heartbeat on this
 *                     address should be disabled. A value of UINT32_MAX
 *                     (4294967295), when modifying the parameter,
 *                     specifies that a heartbeat should be sent
 *                     immediately to the peer address, and the current
 *                     interval should remain unchanged.
 *   spp_pathmaxrxt  - This contains the maximum number of
 *                     retransmissions before this address shall be
 *                     considered unreachable.
 */
static int sctp_setsockopt_peer_addr_params(struct sock *sk,
                                            char *optval, int optlen)
{
        struct sctp_paddrparams params;
        struct sctp_transport *trans;
        int error;

        if (optlen != sizeof(struct sctp_paddrparams))
                return -EINVAL;
        if (copy_from_user(&params, optval, optlen))
                return -EFAULT;

        trans = sctp_addr_id2transport(sk, &params.spp_address,
                                       params.spp_assoc_id);
        if (!trans)
                return -EINVAL;

        /* Applications can enable or disable heartbeats for any peer address
         * of an association, modify an address's heartbeat interval, force a
         * heartbeat to be sent immediately, and adjust the address's maximum
         * number of retransmissions sent before an address is considered
         * unreachable.
         *
         * The value of the heartbeat interval, in milliseconds. A value of
         * UINT32_MAX (4294967295), when modifying the parameter, specifies
         * that a heartbeat should be sent immediately to the peer address,
         * and the current interval should remain unchanged.
         */
        if (0xffffffff == params.spp_hbinterval) {
                error = sctp_primitive_REQUESTHEARTBEAT (trans->asoc, trans);
                if (error)
                        return error;
        } else {
        /* The value of the heartbeat interval, in milliseconds. A value of 0,
         * when modifying the parameter, specifies that the heartbeat on this
         * address should be disabled.
         */
                if (params.spp_hbinterval) {
                        trans->hb_allowed = 1;
                        trans->hb_interval = 
                                MSECS_TO_JIFFIES(params.spp_hbinterval);
                } else
                        trans->hb_allowed = 0;
        }

        /* spp_pathmaxrxt contains the maximum number of retransmissions
         * before this address shall be considered unreachable.
         */
        trans->error_threshold = params.spp_pathmaxrxt;

        return 0;
}

/* 7.1.3 Initialization Parameters (SCTP_INITMSG)
 *
 * Applications can specify protocol parameters for the default association
 * initialization.  The option name argument to setsockopt() and getsockopt()
 * is SCTP_INITMSG.
 *
 * Setting initialization parameters is effective only on an unconnected
 * socket (for UDP-style sockets only future associations are effected
 * by the change).  With TCP-style sockets, this option is inherited by
 * sockets derived from a listener socket.
 */
static int sctp_setsockopt_initmsg(struct sock *sk, char *optval, int optlen)
{
        struct sctp_initmsg sinit;
        struct sctp_opt *sp = sctp_sk(sk);

        if (optlen != sizeof(struct sctp_initmsg))
                return -EINVAL;
        if (copy_from_user(&sinit, optval, optlen))
                return -EFAULT;

        if (sinit.sinit_num_ostreams)
                sp->initmsg.sinit_num_ostreams = sinit.sinit_num_ostreams;      
        if (sinit.sinit_max_instreams)
                sp->initmsg.sinit_max_instreams = sinit.sinit_max_instreams;    
        if (sinit.sinit_max_attempts)
                sp->initmsg.sinit_max_attempts = sinit.sinit_max_attempts;      
        if (sinit.sinit_max_init_timeo)
                sp->initmsg.sinit_max_init_timeo = sinit.sinit_max_init_timeo;  

        return 0;
}

/*
 * 7.1.14 Set default send parameters (SCTP_DEFAULT_SEND_PARAM)
 *
 *   Applications that wish to use the sendto() system call may wish to
 *   specify a default set of parameters that would normally be supplied
 *   through the inclusion of ancillary data.  This socket option allows
 *   such an application to set the default sctp_sndrcvinfo structure.
 *   The application that wishes to use this socket option simply passes
 *   in to this call the sctp_sndrcvinfo structure defined in Section
 *   5.2.2) The input parameters accepted by this call include
 *   sinfo_stream, sinfo_flags, sinfo_ppid, sinfo_context,
 *   sinfo_timetolive.  The user must provide the sinfo_assoc_id field in
 *   to this call if the caller is using the UDP model.
 */
static int sctp_setsockopt_default_send_param(struct sock *sk,
                                                char *optval, int optlen)
{
        struct sctp_sndrcvinfo info;
        struct sctp_association *asoc;
        struct sctp_opt *sp = sctp_sk(sk);

        if (optlen != sizeof(struct sctp_sndrcvinfo))
                return -EINVAL;
        if (copy_from_user(&info, optval, optlen))
                return -EFAULT;

        asoc = sctp_id2assoc(sk, info.sinfo_assoc_id);
        if (!asoc && info.sinfo_assoc_id && sctp_style(sk, UDP))
                return -EINVAL;

        if (asoc) {
                asoc->default_stream = info.sinfo_stream;
                asoc->default_flags = info.sinfo_flags;
                asoc->default_ppid = info.sinfo_ppid;
                asoc->default_context = info.sinfo_context;
                asoc->default_timetolive = info.sinfo_timetolive;
        } else {
                sp->default_stream = info.sinfo_stream;
                sp->default_flags = info.sinfo_flags;
                sp->default_ppid = info.sinfo_ppid;
                sp->default_context = info.sinfo_context;
                sp->default_timetolive = info.sinfo_timetolive;
        }

        return 0;
}

/* 7.1.10 Set Primary Address (SCTP_PRIMARY_ADDR)
 *
 * Requests that the local SCTP stack use the enclosed peer address as
 * the association primary.  The enclosed address must be one of the
 * association peer's addresses.
 */
static int sctp_setsockopt_primary_addr(struct sock *sk, char *optval,
                                        int optlen)
{
        struct sctp_prim prim;
        struct sctp_transport *trans;

        if (optlen != sizeof(struct sctp_prim))
                return -EINVAL;

        if (copy_from_user(&prim, optval, sizeof(struct sctp_prim)))
                return -EFAULT;

        trans = sctp_addr_id2transport(sk, &prim.ssp_addr, prim.ssp_assoc_id);
        if (!trans)
                return -EINVAL;

        sctp_assoc_set_primary(trans->asoc, trans);

        return 0;
}

/*
 * 7.1.5 SCTP_NODELAY
 *
 * Turn on/off any Nagle-like algorithm.  This means that packets are
 * generally sent as soon as possible and no unnecessary delays are
 * introduced, at the cost of more packets in the network.  Expects an
 *  integer boolean flag.
 */
static int sctp_setsockopt_nodelay(struct sock *sk, char *optval,
                                        int optlen)
{
        int val;

        if (optlen < sizeof(int))
                return -EINVAL;
        if (get_user(val, (int *)optval))
                return -EFAULT;

        sctp_sk(sk)->nodelay = (val == 0) ? 0 : 1;
        return 0;
}

/*
 *
 * 7.1.1 SCTP_RTOINFO
 *
 * The protocol parameters used to initialize and bound retransmission
 * timeout (RTO) are tunable. sctp_rtoinfo structure is used to access
 * and modify these parameters.
 * All parameters are time values, in milliseconds.  A value of 0, when
 * modifying the parameters, indicates that the current value should not
 * be changed.
 *
 */
static int sctp_setsockopt_rtoinfo(struct sock *sk, char *optval, int optlen) {
        struct sctp_rtoinfo rtoinfo;
        struct sctp_association *asoc;

        if (optlen != sizeof (struct sctp_rtoinfo))
                return -EINVAL;

        if (copy_from_user(&rtoinfo, optval, optlen))
                return -EFAULT;

        asoc = sctp_id2assoc(sk, rtoinfo.srto_assoc_id);

        /* Set the values to the specific association */
        if (!asoc && rtoinfo.srto_assoc_id && sctp_style(sk, UDP))
                return -EINVAL;

        if (asoc) {
                if (rtoinfo.srto_initial != 0)
                        asoc->rto_initial = 
                                MSECS_TO_JIFFIES(rtoinfo.srto_initial);
                if (rtoinfo.srto_max != 0)
                        asoc->rto_max = MSECS_TO_JIFFIES(rtoinfo.srto_max);
                if (rtoinfo.srto_min != 0)
                        asoc->rto_min = MSECS_TO_JIFFIES(rtoinfo.srto_min);
        } else {
                /* If there is no association or the association-id = 0
                 * set the values to the endpoint.
                 */
                struct sctp_opt *sp = sctp_sk(sk);

                if (rtoinfo.srto_initial != 0)
                        sp->rtoinfo.srto_initial = rtoinfo.srto_initial;
                if (rtoinfo.srto_max != 0)
                        sp->rtoinfo.srto_max = rtoinfo.srto_max;
                if (rtoinfo.srto_min != 0)
                        sp->rtoinfo.srto_min = rtoinfo.srto_min;
        }

        return 0;
}

/*
 *
 * 7.1.2 SCTP_ASSOCINFO
 *
 * This option is used to tune the the maximum retransmission attempts
 * of the association.
 * Returns an error if the new association retransmission value is
 * greater than the sum of the retransmission value  of the peer.
 * See [SCTP] for more information.
 *
 */
static int sctp_setsockopt_associnfo(struct sock *sk, char *optval, int optlen)
{

        struct sctp_assocparams assocparams;
        struct sctp_association *asoc;

        if (optlen != sizeof(struct sctp_assocparams))
                return -EINVAL;
        if (copy_from_user(&assocparams, optval, optlen))
                return -EFAULT;

        asoc = sctp_id2assoc(sk, assocparams.sasoc_assoc_id);

        if (!asoc && assocparams.sasoc_assoc_id && sctp_style(sk, UDP))
                return -EINVAL;

        /* Set the values to the specific association */
        if (asoc) {
                if (assocparams.sasoc_asocmaxrxt != 0)
                        asoc->max_retrans = assocparams.sasoc_asocmaxrxt;
                if (assocparams.sasoc_cookie_life != 0) {
                        asoc->cookie_life.tv_sec =
                                        assocparams.sasoc_cookie_life / 1000;
                        asoc->cookie_life.tv_usec =
                                        (assocparams.sasoc_cookie_life % 1000)
                                        * 1000;
                }
        } else {
                /* Set the values to the endpoint */
                struct sctp_opt *sp = sctp_sk(sk);

                if (assocparams.sasoc_asocmaxrxt != 0)
                        sp->assocparams.sasoc_asocmaxrxt =
                                                assocparams.sasoc_asocmaxrxt;
                if (assocparams.sasoc_cookie_life != 0)
                        sp->assocparams.sasoc_cookie_life =
                                                assocparams.sasoc_cookie_life;
        }
        return 0;
}

/*
 * 7.1.16 Set/clear IPv4 mapped addresses (SCTP_I_WANT_MAPPED_V4_ADDR)
 *
 * This socket option is a boolean flag which turns on or off mapped V4
 * addresses.  If this option is turned on and the socket is type
 * PF_INET6, then IPv4 addresses will be mapped to V6 representation.
 * If this option is turned off, then no mapping will be done of V4
 * addresses and a user will receive both PF_INET6 and PF_INET type
 * addresses on the socket.
 */
static int sctp_setsockopt_mappedv4(struct sock *sk, char *optval, int optlen)
{
        int val;
        struct sctp_opt *sp = sctp_sk(sk);

        if (optlen < sizeof(int))
                return -EINVAL;
        if (get_user(val, (int *)optval))
                return -EFAULT;
        if (val)
                sp->v4mapped = 1;
        else
                sp->v4mapped = 0;

        return 0;
}

/*
 * 7.1.17 Set the maximum fragrmentation size (SCTP_MAXSEG)
 *
 * This socket option specifies the maximum size to put in any outgoing
 * SCTP chunk.  If a message is larger than this size it will be
 * fragmented by SCTP into the specified size.  Note that the underlying
 * SCTP implementation may fragment into smaller sized chunks when the
 * PMTU of the underlying association is smaller than the value set by
 * the user.
 */
static int sctp_setsockopt_maxseg(struct sock *sk, char *optval, int optlen)
{
        struct sctp_association *asoc;
        struct list_head *pos;
        struct sctp_opt *sp = sctp_sk(sk);
        int val;

        if (optlen < sizeof(int))
                return -EINVAL;
        if (get_user(val, (int *)optval))
                return -EFAULT;
        if ((val < 8) || (val > SCTP_MAX_CHUNK_LEN))
                return -EINVAL;
        sp->user_frag = val;

        if (val) {
                /* Update the frag_point of the existing associations. */
                list_for_each(pos, &(sp->ep->asocs)) {
                        asoc = list_entry(pos, struct sctp_association, asocs);
                        asoc->frag_point = sctp_frag_point(sp, asoc->pmtu); 
                }
        }

        return 0;
}


/*
 *  7.1.9 Set Peer Primary Address (SCTP_SET_PEER_PRIMARY_ADDR)
 *
 *   Requests that the peer mark the enclosed address as the association
 *   primary. The enclosed address must be one of the association's
 *   locally bound addresses. The following structure is used to make a
 *   set primary request:
 */
static int sctp_setsockopt_peer_primary_addr(struct sock *sk, char *optval,
                                             int optlen)
{
        struct sctp_opt         *sp;
        struct sctp_endpoint    *ep;
        struct sctp_association *asoc = NULL;
        struct sctp_setpeerprim prim;
        struct sctp_chunk       *chunk;
        int                     err;

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

        if (!sctp_addip_enable)
                return -EPERM;

        if (optlen != sizeof(struct sctp_setpeerprim))
                return -EINVAL;

        if (copy_from_user(&prim, optval, optlen))
                return -EFAULT;

        asoc = sctp_id2assoc(sk, prim.sspp_assoc_id);
        if (!asoc) 
                return -EINVAL;

        if (!asoc->peer.asconf_capable)
                return -EPERM;

        if (asoc->peer.addip_disabled_mask & SCTP_PARAM_SET_PRIMARY)
                return -EPERM;

        if (!sctp_state(asoc, ESTABLISHED))
                return -ENOTCONN;

        if (!sctp_assoc_lookup_laddr(asoc, (union sctp_addr *)&prim.sspp_addr))
                return -EADDRNOTAVAIL;

        /* Create an ASCONF chunk with SET_PRIMARY parameter    */
        chunk = sctp_make_asconf_set_prim(asoc,
                                          (union sctp_addr *)&prim.sspp_addr);
        if (!chunk)
                return -ENOMEM;

        err = sctp_send_asconf(asoc, chunk);

        SCTP_DEBUG_PRINTK("We set peer primary addr primitively.\n");

        return err;
}


/* API 6.2 setsockopt(), getsockopt()
 *
 * Applications use setsockopt() and getsockopt() to set or retrieve
 * socket options.  Socket options are used to change the default
 * behavior of sockets calls.  They are described in Section 7.
 *
 * The syntax is:
 *
 *   ret = getsockopt(int sd, int level, int optname, void *optval,
 *                    int *optlen);
 *   ret = setsockopt(int sd, int level, int optname, const void *optval,
 *                    int optlen);
 *
 *   sd      - the socket descript.
 *   level   - set to IPPROTO_SCTP for all SCTP options.
 *   optname - the option name.
 *   optval  - the buffer to store the value of the option.
 *   optlen  - the size of the buffer.
 */
SCTP_STATIC int sctp_setsockopt(struct sock *sk, int level, int optname,
                                char *optval, int optlen)
{
        int retval = 0;

        SCTP_DEBUG_PRINTK("sctp_setsockopt(sk: %p... optname: %d)\n",
                          sk, optname);

        /* I can hardly begin to describe how wrong this is.  This is
         * so broken as to be worse than useless.  The API draft
         * REALLY is NOT helpful here...  I am not convinced that the
         * semantics of setsockopt() with a level OTHER THAN SOL_SCTP
         * are at all well-founded.
         */
        if (level != SOL_SCTP) {
                struct sctp_af *af = sctp_sk(sk)->pf->af;
                retval = af->setsockopt(sk, level, optname, optval, optlen);
                goto out_nounlock;
        }

        sctp_lock_sock(sk);

        switch (optname) {
        case SCTP_SOCKOPT_BINDX_ADD:
                /* 'optlen' is the size of the addresses buffer. */
                retval = sctp_setsockopt_bindx(sk, (struct sockaddr *)optval,
                                               optlen, SCTP_BINDX_ADD_ADDR);
                break;

        case SCTP_SOCKOPT_BINDX_REM:
                /* 'optlen' is the size of the addresses buffer. */
                retval = sctp_setsockopt_bindx(sk, (struct sockaddr *)optval,
                                               optlen, SCTP_BINDX_REM_ADDR);
                break;

        case SCTP_DISABLE_FRAGMENTS:
                retval = sctp_setsockopt_disable_fragments(sk, optval, optlen);
                break;

        case SCTP_EVENTS:
                retval = sctp_setsockopt_events(sk, optval, optlen);
                break;

        case SCTP_AUTOCLOSE:
                retval = sctp_setsockopt_autoclose(sk, optval, optlen);
                break;

        case SCTP_PEER_ADDR_PARAMS:
                retval = sctp_setsockopt_peer_addr_params(sk, optval, optlen);
                break;

        case SCTP_INITMSG:
                retval = sctp_setsockopt_initmsg(sk, optval, optlen);
                break;
        case SCTP_DEFAULT_SEND_PARAM:
                retval = sctp_setsockopt_default_send_param(sk, optval,
                                                            optlen);
                break;
        case SCTP_PRIMARY_ADDR:
                retval = sctp_setsockopt_primary_addr(sk, optval, optlen);
                break;
        case SCTP_SET_PEER_PRIMARY_ADDR:
                retval = sctp_setsockopt_peer_primary_addr(sk, optval, optlen);
                break;
        case SCTP_NODELAY:
                retval = sctp_setsockopt_nodelay(sk, optval, optlen);
                break;
        case SCTP_RTOINFO:
                retval = sctp_setsockopt_rtoinfo(sk, optval, optlen);
                break;
        case SCTP_ASSOCINFO:
                retval = sctp_setsockopt_associnfo(sk, optval, optlen);
                break;
        case SCTP_I_WANT_MAPPED_V4_ADDR:
                retval = sctp_setsockopt_mappedv4(sk, optval, optlen);
                break;
        case SCTP_MAXSEG:
                retval = sctp_setsockopt_maxseg(sk, optval, optlen);
                break;
        default:
                retval = -ENOPROTOOPT;
                break;
        };

        sctp_release_sock(sk);

out_nounlock:
        return retval;
}

/* API 3.1.6 connect() - UDP Style Syntax
 *
 * An application may use the connect() call in the UDP model to initiate an
 * association without sending data.
 *
 * The syntax is:
 *
 * ret = connect(int sd, const struct sockaddr *nam, socklen_t len);
 *
 * sd: the socket descriptor to have a new association added to.
 *
 * nam: the address structure (either struct sockaddr_in or struct
 *    sockaddr_in6 defined in RFC2553 [7]).
 *
 * len: the size of the address.
 */
SCTP_STATIC int sctp_connect(struct sock *sk, struct sockaddr *uaddr,
                             int addr_len)
{
        struct sctp_opt *sp;
        struct sctp_endpoint *ep;
        struct sctp_association *asoc;
        struct sctp_transport *transport;
        union sctp_addr to;
        struct sctp_af *af;
        sctp_scope_t scope;
        long timeo;
        int err = 0;

        sctp_lock_sock(sk);

        SCTP_DEBUG_PRINTK("%s - sk: %p, sockaddr: %p, addr_len: %d)\n",
                          __FUNCTION__, sk, uaddr, addr_len);

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

        /* connect() cannot be done on a socket that is already in ESTABLISHED
         * state - UDP-style peeled off socket or a TCP-style socket that
         * is already connected.
         * It cannot be done even on a TCP-style listening socket.
         */
        if (sctp_sstate(sk, ESTABLISHED) ||
            (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))) {
                err = -EISCONN;
                goto out_unlock;
        }

        err = sctp_verify_addr(sk, (union sctp_addr *)uaddr, addr_len);
        if (err)
                goto out_unlock;

        if (addr_len > sizeof(to))
                addr_len = sizeof(to);
        memcpy(&to, uaddr, addr_len);
        to.v4.sin_port = ntohs(to.v4.sin_port);

        asoc = sctp_endpoint_lookup_assoc(ep, &to, &transport);
        if (asoc) {
                if (asoc->state >= SCTP_STATE_ESTABLISHED)
                        err = -EISCONN;
                else
                        err = -EALREADY;
                goto out_unlock;
        }

        /* If we could not find a matching association on the endpoint,
         * make sure that there is no peeled-off association matching the
         * peer address even on another socket.
         */
        if (sctp_endpoint_is_peeled_off(ep, &to)) {
                err = -EADDRNOTAVAIL;
                goto out_unlock;
        }

        /* If a bind() or sctp_bindx() is not called prior to a connect()
         * call, the system picks an ephemeral port and will choose an address
         * set equivalent to binding with a wildcard address.
         */
        if (!ep->base.bind_addr.port) {
                if (sctp_autobind(sk)) {
                        err = -EAGAIN;
                        goto out_unlock;
                }
        }

        scope = sctp_scope(&to);
        asoc = sctp_association_new(ep, sk, scope, GFP_KERNEL);
        if (!asoc) {
                err = -ENOMEM;
                goto out_unlock;
        }

        /* Prime the peer's transport structures.  */
        transport = sctp_assoc_add_peer(asoc, &to, GFP_KERNEL);
        if (!transport) {
                sctp_association_free(asoc);
                goto out_unlock;
        }
        err = sctp_assoc_set_bind_addr_from_ep(asoc, GFP_KERNEL);
        if (err < 0) {
                sctp_association_free(asoc);
                goto out_unlock;
        }

        err = sctp_primitive_ASSOCIATE(asoc, NULL);
        if (err < 0) {
                sctp_association_free(asoc);
                goto out_unlock;
        }

        /* Initialize sk's dport and daddr for getpeername() */
        inet_sk(sk)->dport = htons(asoc->peer.port);
        af = sctp_get_af_specific(to.sa.sa_family);
        af->to_sk_daddr(&to, sk);

        timeo = sock_sndtimeo(sk, sk->sk_socket->file->f_flags & O_NONBLOCK);
        err = sctp_wait_for_connect(asoc, &timeo);

out_unlock:
        sctp_release_sock(sk);

        return err;
}

/* FIXME: Write comments. */
SCTP_STATIC int sctp_disconnect(struct sock *sk, int flags)
{
        return -EOPNOTSUPP; /* STUB */
}

/* 4.1.4 accept() - TCP Style Syntax
 *
 * Applications use accept() call to remove an established SCTP
 * association from the accept queue of the endpoint.  A new socket
 * descriptor will be returned from accept() to represent the newly
 * formed association.
 */
SCTP_STATIC struct sock *sctp_accept(struct sock *sk, int flags, int *err)
{
        struct sctp_opt *sp;
        struct sctp_endpoint *ep;
        struct sock *newsk = NULL;
        struct sctp_association *asoc;
        long timeo;
        int error = 0;

        sctp_lock_sock(sk);

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

        if (!sctp_style(sk, TCP)) {
                error = -EOPNOTSUPP;
                goto out;
        }

        if (!sctp_sstate(sk, LISTENING)) {
                error = -EINVAL;
                goto out;
        }

        timeo = sock_rcvtimeo(sk, sk->sk_socket->file->f_flags & O_NONBLOCK);

        error = sctp_wait_for_accept(sk, timeo);
        if (error)
                goto out;

        /* We treat the list of associations on the endpoint as the accept
         * queue and pick the first association on the list.
         */
        asoc = list_entry(ep->asocs.next, struct sctp_association, asocs);

        newsk = sp->pf->create_accept_sk(sk, asoc);
        if (!newsk) {
                error = -ENOMEM;
                goto out;
        }

        /* Populate the fields of the newsk from the oldsk and migrate the
         * asoc to the newsk.
         */
        sctp_sock_migrate(sk, newsk, asoc, SCTP_SOCKET_TCP);

out:
        sctp_release_sock(sk);
        *err = error;
        return newsk;
}

/* The SCTP ioctl handler. */
SCTP_STATIC int sctp_ioctl(struct sock *sk, int cmd, unsigned long arg)
{
        return -ENOIOCTLCMD;
}

/* This is the function which gets called during socket creation to
 * initialized the SCTP-specific portion of the sock.
 * The sock structure should already be zero-filled memory.
 */
SCTP_STATIC int sctp_init_sock(struct sock *sk)
{
        struct sctp_endpoint *ep;
        struct sctp_opt *sp;

        SCTP_DEBUG_PRINTK("sctp_init_sock(sk: %p)\n", sk);

        sp = sctp_sk(sk);

        /* Initialize the SCTP per socket area.  */
        switch (sk->sk_type) {
        case SOCK_SEQPACKET:
                sp->type = SCTP_SOCKET_UDP;
                break;
        case SOCK_STREAM:
                sp->type = SCTP_SOCKET_TCP;
                break;
        default:
                return -ESOCKTNOSUPPORT;
        }

        /* Initialize default send parameters. These parameters can be
         * modified with the SCTP_DEFAULT_SEND_PARAM socket option.
         */
        sp->default_stream = 0;
        sp->default_ppid = 0;
        sp->default_flags = 0;
        sp->default_context = 0;
        sp->default_timetolive = 0;

        /* Initialize default setup parameters. These parameters
         * can be modified with the SCTP_INITMSG socket option or
         * overridden by the SCTP_INIT CMSG.
         */
        sp->initmsg.sinit_num_ostreams   = sctp_max_outstreams;
        sp->initmsg.sinit_max_instreams  = sctp_max_instreams;
        sp->initmsg.sinit_max_attempts   = sctp_max_retrans_init;
        sp->initmsg.sinit_max_init_timeo = JIFFIES_TO_MSECS(sctp_rto_max);

        /* Initialize default RTO related parameters.  These parameters can
         * be modified for with the SCTP_RTOINFO socket option.
         */
        sp->rtoinfo.srto_initial = JIFFIES_TO_MSECS(sctp_rto_initial);
        sp->rtoinfo.srto_max     = JIFFIES_TO_MSECS(sctp_rto_max);
        sp->rtoinfo.srto_min     = JIFFIES_TO_MSECS(sctp_rto_min);

        /* Initialize default association related parameters. These parameters
         * can be modified with the SCTP_ASSOCINFO socket option.
         */
        sp->assocparams.sasoc_asocmaxrxt = sctp_max_retrans_association;
        sp->assocparams.sasoc_number_peer_destinations = 0;
        sp->assocparams.sasoc_peer_rwnd = 0;
        sp->assocparams.sasoc_local_rwnd = 0;
        sp->assocparams.sasoc_cookie_life = 
                JIFFIES_TO_MSECS(sctp_valid_cookie_life);

        /* Initialize default event subscriptions. By default, all the
         * options are off. 
         */
        memset(&sp->subscribe, 0, sizeof(struct sctp_event_subscribe));

        /* Default Peer Address Parameters.  These defaults can
         * be modified via SCTP_PEER_ADDR_PARAMS
         */
        sp->paddrparam.spp_hbinterval = JIFFIES_TO_MSECS(sctp_hb_interval);
        sp->paddrparam.spp_pathmaxrxt = sctp_max_retrans_path;

        /* If enabled no SCTP message fragmentation will be performed.
         * Configure through SCTP_DISABLE_FRAGMENTS socket option.
         */
        sp->disable_fragments = 0;

        /* Turn on/off any Nagle-like algorithm.  */
        sp->nodelay           = 1;

        /* Enable by default. */
        sp->v4mapped          = 1;

        /* Auto-close idle associations after the configured
         * number of seconds.  A value of 0 disables this
         * feature.  Configure through the SCTP_AUTOCLOSE socket option,
         * for UDP-style sockets only.
         */
        sp->autoclose         = 0;

        /* User specified fragmentation limit. */
        sp->user_frag         = 0;

        sp->pf = sctp_get_pf_specific(sk->sk_family);

        /* Control variables for partial data delivery. */
        sp->pd_mode           = 0;
        skb_queue_head_init(&sp->pd_lobby);

        /* Create a per socket endpoint structure.  Even if we
         * change the data structure relationships, this may still
         * be useful for storing pre-connect address information.
         */
        ep = sctp_endpoint_new(sk, GFP_KERNEL);
        if (!ep)
                return -ENOMEM;

        sp->ep = ep;
        sp->hmac = NULL;

        SCTP_DBG_OBJCNT_INC(sock);
        return 0;
}

/* Cleanup any SCTP per socket resources.  */
SCTP_STATIC int sctp_destroy_sock(struct sock *sk)
{
        struct sctp_endpoint *ep;

        SCTP_DEBUG_PRINTK("sctp_destroy_sock(sk: %p)\n", sk);

        /* Release our hold on the endpoint. */
        ep = sctp_sk(sk)->ep;
        sctp_endpoint_free(ep);

        return 0;
}

/* API 4.1.7 shutdown() - TCP Style Syntax
 *     int shutdown(int socket, int how);
 *
 *     sd      - the socket descriptor of the association to be closed.
 *     how     - Specifies the type of shutdown.  The  values  are
 *               as follows:
 *               SHUT_RD
 *                     Disables further receive operations. No SCTP
 *                     protocol action is taken.
 *               SHUT_WR
 *                     Disables further send operations, and initiates
 *                     the SCTP shutdown sequence.
 *               SHUT_RDWR
 *                     Disables further send  and  receive  operations
 *                     and initiates the SCTP shutdown sequence.
 */
SCTP_STATIC void sctp_shutdown(struct sock *sk, int how)
{
        struct sctp_endpoint *ep;
        struct sctp_association *asoc;

        if (!sctp_style(sk, TCP))
                return;

        if (how & SEND_SHUTDOWN) {
                ep = sctp_sk(sk)->ep;
                if (!list_empty(&ep->asocs)) {
                        asoc = list_entry(ep->asocs.next,
                                          struct sctp_association, asocs);
                        sctp_primitive_SHUTDOWN(asoc, NULL);
                }
        }
}

/* 7.2.1 Association Status (SCTP_STATUS)

 * Applications can retrieve current status information about an
 * association, including association state, peer receiver window size,
 * number of unacked data chunks, and number of data chunks pending
 * receipt.  This information is read-only.
 */
static int sctp_getsockopt_sctp_status(struct sock *sk, int len, char *optval,
                                       int *optlen)
{
        struct sctp_status status;
        struct sctp_association *asoc = NULL;
        struct sctp_transport *transport;
        sctp_assoc_t associd;
        int retval = 0;

        if (len != sizeof(status)) {
                retval = -EINVAL;
                goto out;
        }

        if (copy_from_user(&status, optval, sizeof(status))) {
                retval = -EFAULT;
                goto out;
        }

        associd = status.sstat_assoc_id;
        asoc = sctp_id2assoc(sk, associd);
        if (!asoc) {
                retval = -EINVAL;
                goto out;
        }

        transport = asoc->peer.primary_path;

        status.sstat_assoc_id = sctp_assoc2id(asoc);
        status.sstat_state = asoc->state;
        status.sstat_rwnd =  asoc->peer.rwnd;
        status.sstat_unackdata = asoc->unack_data;

        status.sstat_penddata = sctp_tsnmap_pending(&asoc->peer.tsn_map);
        status.sstat_instrms = asoc->c.sinit_max_instreams;
        status.sstat_outstrms = asoc->c.sinit_num_ostreams;
        status.sstat_fragmentation_point = asoc->frag_point;
        status.sstat_primary.spinfo_assoc_id = sctp_assoc2id(transport->asoc);
        memcpy(&status.sstat_primary.spinfo_address,
               &(transport->ipaddr), sizeof(union sctp_addr));
        /* Map ipv4 address into v4-mapped-on-v6 address.  */
        sctp_get_pf_specific(sk->sk_family)->addr_v4map(sctp_sk(sk),
                (union sctp_addr *)&status.sstat_primary.spinfo_address);
        status.sstat_primary.spinfo_state = transport->active;
        status.sstat_primary.spinfo_cwnd = transport->cwnd;
        status.sstat_primary.spinfo_srtt = transport->srtt;
        status.sstat_primary.spinfo_rto = JIFFIES_TO_MSECS(transport->rto);
        status.sstat_primary.spinfo_mtu = transport->pmtu;

        if (put_user(len, optlen)) {
                retval = -EFAULT;
                goto out;
        }

        SCTP_DEBUG_PRINTK("sctp_getsockopt_sctp_status(%d): %d %d %p\n",
                          len, status.sstat_state, status.sstat_rwnd,
                          status.sstat_assoc_id);

        if (copy_to_user(optval, &status, len)) {
                retval = -EFAULT;
                goto out;
        }

out:
        return (retval);
}


/* 7.2.2 Peer Address Information (SCTP_GET_PEER_ADDR_INFO)
 *
 * Applications can retrieve information about a specific peer address
 * of an association, including its reachability state, congestion
 * window, and retransmission timer values.  This information is
 * read-only.
 */
static int sctp_getsockopt_peer_addr_info(struct sock *sk, int len,
                                          char *optval, int *optlen)
{
        struct sctp_paddrinfo pinfo;
        struct sctp_transport *transport;
        int retval = 0;

        if (len != sizeof(pinfo)) {
                retval = -EINVAL;
                goto out;
        }

        if (copy_from_user(&pinfo, optval, sizeof(pinfo))) {
                retval = -EFAULT;
                goto out;
        }

        transport = sctp_addr_id2transport(sk, &pinfo.spinfo_address,
                                           pinfo.spinfo_assoc_id);
        if (!transport)
                return -EINVAL;

        pinfo.spinfo_assoc_id = sctp_assoc2id(transport->asoc);
        pinfo.spinfo_state = transport->active;
        pinfo.spinfo_cwnd = transport->cwnd;
        pinfo.spinfo_srtt = transport->srtt;
        pinfo.spinfo_rto = JIFFIES_TO_MSECS(transport->rto);
        pinfo.spinfo_mtu = transport->pmtu;

        if (put_user(len, optlen)) {
                retval = -EFAULT;
                goto out;
        }

        if (copy_to_user(optval, &pinfo, len)) {
                retval = -EFAULT;
                goto out;
        }

out:
        return (retval);
}

/* 7.1.12 Enable/Disable message fragmentation (SCTP_DISABLE_FRAGMENTS)
 *
 * This option is a on/off flag.  If enabled no SCTP message
 * fragmentation will be performed.  Instead if a message being sent
 * exceeds the current PMTU size, the message will NOT be sent and
 * instead a error will be indicated to the user.
 */
static int sctp_getsockopt_disable_fragments(struct sock *sk, int len,
                                                    char *optval, int *optlen)
{
        int val;

        if (len < sizeof(int))
                return -EINVAL;

        len = sizeof(int);
        val = (sctp_sk(sk)->disable_fragments == 1);
        if (put_user(len, optlen))
                return -EFAULT;
        if (copy_to_user(optval, &val, len))
                return -EFAULT;
        return 0;
}

/* 7.1.15 Set notification and ancillary events (SCTP_EVENTS)
 *
 * This socket option is used to specify various notifications and
 * ancillary data the user wishes to receive.
 */
static int sctp_getsockopt_events(struct sock *sk, int len, char *optval,
                                  int *optlen)
{
        if (len != sizeof(struct sctp_event_subscribe))
                return -EINVAL;
        if (copy_to_user(optval, &sctp_sk(sk)->subscribe, len))
                return -EFAULT;
        return 0;
}

/* 7.1.8 Automatic Close of associations (SCTP_AUTOCLOSE)
 *
 * This socket option is applicable to the UDP-style socket only.  When
 * set it will cause associations that are idle for more than the
 * specified number of seconds to automatically close.  An association
 * being idle is defined an association that has NOT sent or received
 * user data.  The special value of '0' indicates that no automatic
 * close of any associations should be performed.  The option expects an
 * integer defining the number of seconds of idle time before an
 * association is closed.
 */
static int sctp_getsockopt_autoclose(struct sock *sk, int len, char *optval, int *optlen)
{
        /* Applicable to UDP-style socket only */
        if (sctp_style(sk, TCP))
                return -EOPNOTSUPP;
        if (len != sizeof(int))
                return -EINVAL;
        if (copy_to_user(optval, &sctp_sk(sk)->autoclose, len))
                return -EFAULT;
        return 0;
}

/* Helper routine to branch off an association to a new socket.  */
SCTP_STATIC int sctp_do_peeloff(struct sctp_association *asoc,
                                struct socket **sockp)
{
        struct sock *sk = asoc->base.sk;
        struct socket *sock;
        int err = 0;

        /* An association cannot be branched off from an already peeled-off
         * socket, nor is this supported for tcp style sockets.
         */
        if (!sctp_style(sk, UDP))
                return -EINVAL;

        /* Create a new socket.  */
        err = sock_create(sk->sk_family, SOCK_SEQPACKET, IPPROTO_SCTP, &sock);
        if (err < 0)
                return err;

        /* Populate the fields of the newsk from the oldsk and migrate the
         * asoc to the newsk.
         */
        sctp_sock_migrate(sk, sock->sk, asoc, SCTP_SOCKET_UDP_HIGH_BANDWIDTH);
        *sockp = sock;

        return err;
}

static int sctp_getsockopt_peeloff(struct sock *sk, int len, char *optval, int *optlen)
{
        sctp_peeloff_arg_t peeloff;
        struct socket *newsock;
        int retval = 0;
        struct sctp_association *asoc;

        if (len != sizeof(sctp_peeloff_arg_t))
                return -EINVAL;
        if (copy_from_user(&peeloff, optval, len))
                return -EFAULT;

        asoc = sctp_id2assoc(sk, peeloff.associd);
        if (!asoc) {
                retval = -EINVAL;
                goto out;
        }

        SCTP_DEBUG_PRINTK("%s: sk: %p asoc: %p\n", __FUNCTION__, sk, asoc);

        retval = sctp_do_peeloff(asoc, &newsock);
        if (retval < 0)
                goto out;

        /* Map the socket to an unused fd that can be returned to the user.  */
        retval = sock_map_fd(newsock);
        if (retval < 0) {
                sock_release(newsock);
                goto out;
        }

        SCTP_DEBUG_PRINTK("%s: sk: %p asoc: %p newsk: %p sd: %d\n",
                          __FUNCTION__, sk, asoc, newsock->sk, retval);

        /* Return the fd mapped to the new socket.  */
        peeloff.sd = retval;
        if (copy_to_user(optval, &peeloff, len))
                retval = -EFAULT;

out:
        return retval;
}

/* 7.1.13 Peer Address Parameters (SCTP_PEER_ADDR_PARAMS)
 *
 * Applications can enable or disable heartbeats for any peer address of
 * an association, modify an address's heartbeat interval, force a
 * heartbeat to be sent immediately, and adjust the address's maximum
 * number of retransmissions sent before an address is considered
 * unreachable.  The following structure is used to access and modify an
 * address's parameters:
 *
 *  struct sctp_paddrparams {
 *      sctp_assoc_t            spp_assoc_id;
 *      struct sockaddr_storage spp_address;
 *      uint32_t                spp_hbinterval;
 *      uint16_t                spp_pathmaxrxt;
 *  };
 *
 *   spp_assoc_id    - (UDP style socket) This is filled in the application,
 *                     and identifies the association for this query.
 *   spp_address     - This specifies which address is of interest.
 *   spp_hbinterval  - This contains the value of the heartbeat interval,
 *                     in milliseconds.  A value of 0, when modifying the
 *                     parameter, specifies that the heartbeat on this
 *                     address should be disabled. A value of UINT32_MAX
 *                     (4294967295), when modifying the parameter,
 *                     specifies that a heartbeat should be sent
 *                     immediately to the peer address, and the current
 *                     interval should remain unchanged.
 *   spp_pathmaxrxt  - This contains the maximum number of
 *                     retransmissions before this address shall be
 *                     considered unreachable.
 */
static int sctp_getsockopt_peer_addr_params(struct sock *sk, int len,
                                                char *optval, int *optlen)
{
        struct sctp_paddrparams params;
        struct sctp_transport *trans;

        if (len != sizeof(struct sctp_paddrparams))
                return -EINVAL;
        if (copy_from_user(&params, optval, *optlen))
                return -EFAULT;

        trans = sctp_addr_id2transport(sk, &params.spp_address,
                                       params.spp_assoc_id);
        if (!trans)
                return -EINVAL;

        /* The value of the heartbeat interval, in milliseconds. A value of 0,
         * when modifying the parameter, specifies that the heartbeat on this
         * address should be disabled.
         */
        if (!trans->hb_allowed)
                params.spp_hbinterval = 0;
        else
                params.spp_hbinterval = JIFFIES_TO_MSECS(trans->hb_interval);

        /* spp_pathmaxrxt contains the maximum number of retransmissions
         * before this address shall be considered unreachable.
         */
        params.spp_pathmaxrxt = trans->error_threshold;

        if (copy_to_user(optval, &params, len))
                return -EFAULT;

        if (put_user(len, optlen))
                return -EFAULT;

        return 0;
}

/* 7.1.3 Initialization Parameters (SCTP_INITMSG)
 *
 * Applications can specify protocol parameters for the default association
 * initialization.  The option name argument to setsockopt() and getsockopt()
 * is SCTP_INITMSG.
 *
 * Setting initialization parameters is effective only on an unconnected
 * socket (for UDP-style sockets only future associations are effected
 * by the change).  With TCP-style sockets, this option is inherited by
 * sockets derived from a listener socket.
 */
static int sctp_getsockopt_initmsg(struct sock *sk, int len, char *optval, int *optlen)
{
        if (len != sizeof(struct sctp_initmsg))
                return -EINVAL;
        if (copy_to_user(optval, &sctp_sk(sk)->initmsg, len))
                return -EFAULT;
        return 0;
}

static int sctp_getsockopt_peer_addrs_num(struct sock *sk, int len,
                                          char *optval, int *optlen)
{
        sctp_assoc_t id;
        struct sctp_association *asoc;
        struct list_head *pos;
        int cnt = 0;

        if (len != sizeof(sctp_assoc_t))
                return -EINVAL;

        if (copy_from_user(&id, optval, sizeof(sctp_assoc_t)))
                return -EFAULT;

        /* For UDP-style sockets, id specifies the association to query.  */
        asoc = sctp_id2assoc(sk, id);
        if (!asoc)
                return -EINVAL;

        list_for_each(pos, &asoc->peer.transport_addr_list) {
                cnt ++;
        }

        return cnt;
}

static int sctp_getsockopt_peer_addrs(struct sock *sk, int len,
                                      char *optval, int *optlen)
{
        struct sctp_association *asoc;
        struct list_head *pos;
        int cnt = 0;
        struct sctp_getaddrs getaddrs;
        struct sctp_transport *from;
        void *to;
        union sctp_addr temp;
        struct sctp_opt *sp = sctp_sk(sk);
        int addrlen;

        if (len != sizeof(struct sctp_getaddrs))
                return -EINVAL;

        if (copy_from_user(&getaddrs, optval, sizeof(struct sctp_getaddrs)))
                return -EFAULT;

        if (getaddrs.addr_num <= 0) return -EINVAL;

        /* For UDP-style sockets, id specifies the association to query.  */
        asoc = sctp_id2assoc(sk, getaddrs.assoc_id);
        if (!asoc)
                return -EINVAL;

        to = (void *)getaddrs.addrs;
        list_for_each(pos, &asoc->peer.transport_addr_list) {
                from = list_entry(pos, struct sctp_transport, transports);
                memcpy(&temp, &from->ipaddr, sizeof(temp));
                sctp_get_pf_specific(sk->sk_family)->addr_v4map(sp, &temp);
                addrlen = sctp_get_af_specific(sk->sk_family)->sockaddr_len;
                temp.v4.sin_port = htons(temp.v4.sin_port);
                if (copy_to_user(to, &temp, addrlen))
                        return -EFAULT;
                to += addrlen ;
                cnt ++;
                if (cnt >= getaddrs.addr_num) break;
        }
        getaddrs.addr_num = cnt;
        if (copy_to_user(optval, &getaddrs, sizeof(struct sctp_getaddrs)))
                return -EFAULT;

        return 0;
}

static int sctp_getsockopt_local_addrs_num(struct sock *sk, int len,
                                                char *optval, int *optlen)
{
        sctp_assoc_t id;
        struct sctp_bind_addr *bp;
        struct sctp_association *asoc;
        struct list_head *pos;
        int cnt = 0;

        if (len != sizeof(sctp_assoc_t))
                return -EINVAL;

        if (copy_from_user(&id, optval, sizeof(sctp_assoc_t)))
                return -EFAULT;

        /*
         *  For UDP-style sockets, id specifies the association to query.
         *  If the id field is set to the value '0' then the locally bound
         *  addresses are returned without regard to any particular
         *  association.
         */
        if (0 == id) {
                bp = &sctp_sk(sk)->ep->base.bind_addr;
        } else {
                asoc = sctp_id2assoc(sk, id);
                if (!asoc)
                        return -EINVAL;
                bp = &asoc->base.bind_addr;
        }

        list_for_each(pos, &bp->address_list) {
                cnt ++;
        }

        return cnt;
}

static int sctp_getsockopt_local_addrs(struct sock *sk, int len,
                                        char *optval, int *optlen)
{
        struct sctp_bind_addr *bp;
        struct sctp_association *asoc;
        struct list_head *pos;
        int cnt = 0;
        struct sctp_getaddrs getaddrs;
        struct sctp_sockaddr_entry *from;
        void *to;
        union sctp_addr temp;
        struct sctp_opt *sp = sctp_sk(sk);
        int addrlen;

        if (len != sizeof(struct sctp_getaddrs))
                return -EINVAL;

        if (copy_from_user(&getaddrs, optval, sizeof(struct sctp_getaddrs)))
                return -EFAULT;

        if (getaddrs.addr_num <= 0) return -EINVAL;
        /*
         *  For UDP-style sockets, id specifies the association to query.
         *  If the id field is set to the value '0' then the locally bound
         *  addresses are returned without regard to any particular
         *  association.
         */
        if (0 == getaddrs.assoc_id) {
                bp = &sctp_sk(sk)->ep->base.bind_addr;
        } else {
                asoc = sctp_id2assoc(sk, getaddrs.assoc_id);
                if (!asoc)
                        return -EINVAL;
                bp = &asoc->base.bind_addr;
        }

        to = (void *)getaddrs.addrs;
        list_for_each(pos, &bp->address_list) {
                from = list_entry(pos,
                                struct sctp_sockaddr_entry,
                                list);
                memcpy(&temp, &from->a, sizeof(temp));
                sctp_get_pf_specific(sk->sk_family)->addr_v4map(sp, &temp);
                addrlen = sctp_get_af_specific(temp.sa.sa_family)->sockaddr_len;
                temp.v4.sin_port = htons(temp.v4.sin_port);
                if (copy_to_user(to, &temp, addrlen))
                        return -EFAULT;
                to += addrlen;
                cnt ++;
                if (cnt >= getaddrs.addr_num) break;
        }
        getaddrs.addr_num = cnt;
        if (copy_to_user(optval, &getaddrs, sizeof(struct sctp_getaddrs)))
                return -EFAULT;

        return 0;
}

/* 7.1.10 Set Primary Address (SCTP_PRIMARY_ADDR)
 *
 * Requests that the local SCTP stack use the enclosed peer address as
 * the association primary.  The enclosed address must be one of the
 * association peer's addresses.
 */
static int sctp_getsockopt_primary_addr(struct sock *sk, int len,
                                        char *optval, int *optlen)
{
        struct sctp_prim prim;
        struct sctp_association *asoc;
        struct sctp_opt *sp = sctp_sk(sk);

        if (len != sizeof(struct sctp_prim))
                return -EINVAL;

        if (copy_from_user(&prim, optval, sizeof(struct sctp_prim)))
                return -EFAULT;

        asoc = sctp_id2assoc(sk, prim.ssp_assoc_id);
        if (!asoc)
                return -EINVAL;

        if (!asoc->peer.primary_path)
                return -ENOTCONN;
        
        asoc->peer.primary_path->ipaddr.v4.sin_port =
                htons(asoc->peer.primary_path->ipaddr.v4.sin_port);
        memcpy(&prim.ssp_addr, &asoc->peer.primary_path->ipaddr,
               sizeof(union sctp_addr));
        asoc->peer.primary_path->ipaddr.v4.sin_port =
                ntohs(asoc->peer.primary_path->ipaddr.v4.sin_port);

        sctp_get_pf_specific(sk->sk_family)->addr_v4map(sp,
                        (union sctp_addr *)&prim.ssp_addr);

        if (copy_to_user(optval, &prim, sizeof(struct sctp_prim)))
                return -EFAULT;

        return 0;
}

/*
 *
 * 7.1.14 Set default send parameters (SCTP_DEFAULT_SEND_PARAM)
 *
 *   Applications that wish to use the sendto() system call may wish to
 *   specify a default set of parameters that would normally be supplied
 *   through the inclusion of ancillary data.  This socket option allows
 *   such an application to set the default sctp_sndrcvinfo structure.


 *   The application that wishes to use this socket option simply passes
 *   in to this call the sctp_sndrcvinfo structure defined in Section
 *   5.2.2) The input parameters accepted by this call include
 *   sinfo_stream, sinfo_flags, sinfo_ppid, sinfo_context,
 *   sinfo_timetolive.  The user must provide the sinfo_assoc_id field in
 *   to this call if the caller is using the UDP model.
 *
 *   For getsockopt, it get the default sctp_sndrcvinfo structure.
 */
static int sctp_getsockopt_default_send_param(struct sock *sk,
                                        int len, char *optval, int *optlen)
{
        struct sctp_sndrcvinfo info;
        struct sctp_association *asoc;
        struct sctp_opt *sp = sctp_sk(sk);

        if (len != sizeof(struct sctp_sndrcvinfo))
                return -EINVAL;
        if (copy_from_user(&info, optval, sizeof(struct sctp_sndrcvinfo)))
                return -EFAULT;

        asoc = sctp_id2assoc(sk, info.sinfo_assoc_id);
        if (!asoc && info.sinfo_assoc_id && sctp_style(sk, UDP))
                return -EINVAL;

        if (asoc) {
                info.sinfo_stream = asoc->default_stream;
                info.sinfo_flags = asoc->default_flags;
                info.sinfo_ppid = asoc->default_ppid;
                info.sinfo_context = asoc->default_context;
                info.sinfo_timetolive = asoc->default_timetolive;
        } else {
                info.sinfo_stream = sp->default_stream;
                info.sinfo_flags = sp->default_flags;
                info.sinfo_ppid = sp->default_ppid;
                info.sinfo_context = sp->default_context;
                info.sinfo_timetolive = sp->default_timetolive;
        }

        if (copy_to_user(optval, &info, sizeof(struct sctp_sndrcvinfo)))
                return -EFAULT;

        return 0;
}

/*
 *
 * 7.1.5 SCTP_NODELAY
 *
 * Turn on/off any Nagle-like algorithm.  This means that packets are
 * generally sent as soon as possible and no unnecessary delays are
 * introduced, at the cost of more packets in the network.  Expects an
 * integer boolean flag.
 */

static int sctp_getsockopt_nodelay(struct sock *sk, int len,
                                   char *optval, int *optlen)
{
        int val;

        if (len < sizeof(int))
                return -EINVAL;

        len = sizeof(int);
        val = (sctp_sk(sk)->nodelay == 1);
        if (put_user(len, optlen))
                return -EFAULT;
        if (copy_to_user(optval, &val, len))
                return -EFAULT;
        return 0;
}

/*
 *
 * 7.1.1 SCTP_RTOINFO
 *
 * The protocol parameters used to initialize and bound retransmission
 * timeout (RTO) are tunable. sctp_rtoinfo structure is used to access
 * and modify these parameters.
 * All parameters are time values, in milliseconds.  A value of 0, when
 * modifying the parameters, indicates that the current value should not
 * be changed.
 *
 */
static int sctp_getsockopt_rtoinfo(struct sock *sk, int len, char *optval,
                                int *optlen) {
        struct sctp_rtoinfo rtoinfo;
        struct sctp_association *asoc;

        if (len != sizeof (struct sctp_rtoinfo))
                return -EINVAL;

        if (copy_from_user(&rtoinfo, optval, sizeof (struct sctp_rtoinfo)))
                return -EFAULT;

        asoc = sctp_id2assoc(sk, rtoinfo.srto_assoc_id);

        if (!asoc && rtoinfo.srto_assoc_id && sctp_style(sk, UDP))
                return -EINVAL;

        /* Values corresponding to the specific association. */
        if (asoc) {
                rtoinfo.srto_initial = JIFFIES_TO_MSECS(asoc->rto_initial);
                rtoinfo.srto_max = JIFFIES_TO_MSECS(asoc->rto_max);
                rtoinfo.srto_min = JIFFIES_TO_MSECS(asoc->rto_min);
        } else {
                /* Values corresponding to the endpoint. */
                struct sctp_opt *sp = sctp_sk(sk);

                rtoinfo.srto_initial = sp->rtoinfo.srto_initial;
                rtoinfo.srto_max = sp->rtoinfo.srto_max;
                rtoinfo.srto_min = sp->rtoinfo.srto_min;
        }

        if (put_user(len, optlen))
                return -EFAULT;

        if (copy_to_user(optval, &rtoinfo, len))
                return -EFAULT;

        return 0;
}

/*
 *
 * 7.1.2 SCTP_ASSOCINFO
 *
 * This option is used to tune the the maximum retransmission attempts
 * of the association.
 * Returns an error if the new association retransmission value is
 * greater than the sum of the retransmission value  of the peer.
 * See [SCTP] for more information.
 *
 */
static int sctp_getsockopt_associnfo(struct sock *sk, int len, char *optval,
                                     int *optlen)
{

        struct sctp_assocparams assocparams;
        struct sctp_association *asoc;
        struct list_head *pos;
        int cnt = 0;

        if (len != sizeof (struct sctp_assocparams))
                return -EINVAL;

        if (copy_from_user(&assocparams, optval,
                        sizeof (struct sctp_assocparams)))
                return -EFAULT;

        asoc = sctp_id2assoc(sk, assocparams.sasoc_assoc_id);

        if (!asoc && assocparams.sasoc_assoc_id && sctp_style(sk, UDP))
                return -EINVAL;

        /* Values correspoinding to the specific association */
        if (assocparams.sasoc_assoc_id != 0) {
                assocparams.sasoc_asocmaxrxt = asoc->max_retrans;
                assocparams.sasoc_peer_rwnd = asoc->peer.rwnd;
                assocparams.sasoc_local_rwnd = asoc->a_rwnd;
                assocparams.sasoc_cookie_life = (asoc->cookie_life.tv_sec
                                                * 1000) +
                                                (asoc->cookie_life.tv_usec
                                                / 1000);

                list_for_each(pos, &asoc->peer.transport_addr_list) {
                        cnt ++;
                }

                assocparams.sasoc_number_peer_destinations = cnt;
        } else {
                /* Values corresponding to the endpoint */
                struct sctp_opt *sp = sctp_sk(sk);

                assocparams.sasoc_asocmaxrxt = sp->assocparams.sasoc_asocmaxrxt;
                assocparams.sasoc_peer_rwnd = sp->assocparams.sasoc_peer_rwnd;
                assocparams.sasoc_local_rwnd = sp->assocparams.sasoc_local_rwnd;
                assocparams.sasoc_cookie_life =
                                        sp->assocparams.sasoc_cookie_life;
                assocparams.sasoc_number_peer_destinations =
                                        sp->assocparams.
                                        sasoc_number_peer_destinations;
        }

        if (put_user(len, optlen))
                return -EFAULT;

        if (copy_to_user(optval, &assocparams, len))
                return -EFAULT;

        return 0;
}

/*
 * 7.1.16 Set/clear IPv4 mapped addresses (SCTP_I_WANT_MAPPED_V4_ADDR)
 *
 * This socket option is a boolean flag which turns on or off mapped V4
 * addresses.  If this option is turned on and the socket is type
 * PF_INET6, then IPv4 addresses will be mapped to V6 representation.
 * If this option is turned off, then no mapping will be done of V4
 * addresses and a user will receive both PF_INET6 and PF_INET type
 * addresses on the socket.
 */
static int sctp_getsockopt_mappedv4(struct sock *sk, int len,
                                    char *optval, int *optlen)
{
        int val;
        struct sctp_opt *sp = sctp_sk(sk);

        if (len < sizeof(int))
                return -EINVAL;

        len = sizeof(int);
        val = sp->v4mapped;
        if (put_user(len, optlen))
                return -EFAULT;
        if (copy_to_user(optval, &val, len))
                return -EFAULT;

        return 0;
}

/*
 * 7.1.17 Set the maximum fragrmentation size (SCTP_MAXSEG)
 *
 * This socket option specifies the maximum size to put in any outgoing
 * SCTP chunk.  If a message is larger than this size it will be
 * fragmented by SCTP into the specified size.  Note that the underlying
 * SCTP implementation may fragment into smaller sized chunks when the
 * PMTU of the underlying association is smaller than the value set by
 * the user.
 */
static int sctp_getsockopt_maxseg(struct sock *sk, int len,
                                  char *optval, int *optlen)
{
        int val;

        if (len < sizeof(int))
                return -EINVAL;

        len = sizeof(int);

        val = sctp_sk(sk)->user_frag;
        if (put_user(len, optlen))
                return -EFAULT;
        if (copy_to_user(optval, &val, len))
                return -EFAULT;

        return 0;
}

SCTP_STATIC int sctp_getsockopt(struct sock *sk, int level, int optname,
                                char *optval, int *optlen)
{
        int retval = 0;
        int len;

        SCTP_DEBUG_PRINTK("sctp_getsockopt(sk: %p, ...)\n", sk);

        /* I can hardly begin to describe how wrong this is.  This is
         * so broken as to be worse than useless.  The API draft
         * REALLY is NOT helpful here...  I am not convinced that the
         * semantics of getsockopt() with a level OTHER THAN SOL_SCTP
         * are at all well-founded.
         */
        if (level != SOL_SCTP) {
                struct sctp_af *af = sctp_sk(sk)->pf->af;

                retval = af->getsockopt(sk, level, optname, optval, optlen);
                return retval;
        }

        if (get_user(len, optlen))
                return -EFAULT;

        sctp_lock_sock(sk);

        switch (optname) {
        case SCTP_STATUS:
                retval = sctp_getsockopt_sctp_status(sk, len, optval, optlen);
                break;
        case SCTP_DISABLE_FRAGMENTS:
                retval = sctp_getsockopt_disable_fragments(sk, len, optval,
                                                           optlen);
                break;
        case SCTP_EVENTS:
                retval = sctp_getsockopt_events(sk, len, optval, optlen);
                break;
        case SCTP_AUTOCLOSE:
                retval = sctp_getsockopt_autoclose(sk, len, optval, optlen);
                break;
        case SCTP_SOCKOPT_PEELOFF:
                retval = sctp_getsockopt_peeloff(sk, len, optval, optlen);
                break;
        case SCTP_PEER_ADDR_PARAMS:
                retval = sctp_getsockopt_peer_addr_params(sk, len, optval,
                                                          optlen);
                break;
        case SCTP_INITMSG:
                retval = sctp_getsockopt_initmsg(sk, len, optval, optlen);
                break;
        case SCTP_GET_PEER_ADDRS_NUM:
                retval = sctp_getsockopt_peer_addrs_num(sk, len, optval,
                                                        optlen);
                break;
        case SCTP_GET_LOCAL_ADDRS_NUM:
                retval = sctp_getsockopt_local_addrs_num(sk, len, optval,
                                                         optlen);
                break;
        case SCTP_GET_PEER_ADDRS:
                retval = sctp_getsockopt_peer_addrs(sk, len, optval,
                                                    optlen);
                break;
        case SCTP_GET_LOCAL_ADDRS:
                retval = sctp_getsockopt_local_addrs(sk, len, optval,
                                                     optlen);
                break;
        case SCTP_DEFAULT_SEND_PARAM:
                retval = sctp_getsockopt_default_send_param(sk, len,
                                                            optval, optlen);
                break;
        case SCTP_PRIMARY_ADDR:
                retval = sctp_getsockopt_primary_addr(sk, len, optval, optlen);
                break;
        case SCTP_NODELAY:
                retval = sctp_getsockopt_nodelay(sk, len, optval, optlen);
                break;
        case SCTP_RTOINFO:
                retval = sctp_getsockopt_rtoinfo(sk, len, optval, optlen);
                break;
        case SCTP_ASSOCINFO:
                retval = sctp_getsockopt_associnfo(sk, len, optval, optlen);
                break;
        case SCTP_I_WANT_MAPPED_V4_ADDR:
                retval = sctp_getsockopt_mappedv4(sk, len, optval, optlen);
                break;
        case SCTP_MAXSEG:
                retval = sctp_getsockopt_maxseg(sk, len, optval, optlen);
                break;
        case SCTP_GET_PEER_ADDR_INFO:
                retval = sctp_getsockopt_peer_addr_info(sk, len, optval,
                                                        optlen);
                break;
        default:
                retval = -ENOPROTOOPT;
                break;
        };

        sctp_release_sock(sk);
        return retval;
}

static void sctp_hash(struct sock *sk)
{
        /* STUB */
}

static void sctp_unhash(struct sock *sk)
{
        /* STUB */
}

/* Check if port is acceptable.  Possibly find first available port.
 *
 * The port hash table (contained in the 'global' SCTP protocol storage
 * returned by struct sctp_protocol *sctp_get_protocol()). The hash
 * table is an array of 4096 lists (sctp_bind_hashbucket). Each
 * list (the list number is the port number hashed out, so as you
 * would expect from a hash function, all the ports in a given list have
 * such a number that hashes out to the same list number; you were
 * expecting that, right?); so each list has a set of ports, with a
 * link to the socket (struct sock) that uses it, the port number and
 * a fastreuse flag (FIXME: NPI ipg).
 */
static struct sctp_bind_bucket *sctp_bucket_create(
        struct sctp_bind_hashbucket *head, unsigned short snum);

static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
{
        struct sctp_bind_hashbucket *head; /* hash list */
        struct sctp_bind_bucket *pp; /* hash list port iterator */
        unsigned short snum;
        int ret;

        /* NOTE:  Remember to put this back to net order. */
        addr->v4.sin_port = ntohs(addr->v4.sin_port);
        snum = addr->v4.sin_port;

        SCTP_DEBUG_PRINTK("sctp_get_port() begins, snum=%d\n", snum);
        sctp_local_bh_disable();

        if (snum == 0) {
                /* Search for an available port.
                 *
                 * 'sctp_port_rover' was the last port assigned, so
                 * we start to search from 'sctp_port_rover +
                 * 1'. What we do is first check if port 'rover' is
                 * already in the hash table; if not, we use that; if
                 * it is, we try next.
                 */
                int low = sysctl_local_port_range[0];
                int high = sysctl_local_port_range[1];
                int remaining = (high - low) + 1;
                int rover;
                int index;

                sctp_spin_lock(&sctp_port_alloc_lock);
                rover = sctp_port_rover;
                do {
                        rover++;
                        if ((rover < low) || (rover > high))
                                rover = low;
                        index = sctp_phashfn(rover);
                        head = &sctp_port_hashtable[index];
                        sctp_spin_lock(&head->lock);
                        for (pp = head->chain; pp; pp = pp->next)
                                if (pp->port == rover)
                                        goto next;
                        break;
                next:
                        sctp_spin_unlock(&head->lock);
                } while (--remaining > 0);
                sctp_port_rover = rover;
                sctp_spin_unlock(&sctp_port_alloc_lock);

                /* Exhausted local port range during search? */
                ret = 1;
                if (remaining <= 0)
                        goto fail;

                /* OK, here is the one we will use.  HEAD (the port
                 * hash table list entry) is non-NULL and we hold it's
                 * mutex.
                 */
                snum = rover;
        } else {
                /* We are given an specific port number; we verify
                 * that it is not being used. If it is used, we will
                 * exahust the search in the hash list corresponding
                 * to the port number (snum) - we detect that with the
                 * port iterator, pp being NULL.
                 */
                head = &sctp_port_hashtable[sctp_phashfn(snum)];
                sctp_spin_lock(&head->lock);
                for (pp = head->chain; pp; pp = pp->next) {
                        if (pp->port == snum)
                                goto pp_found;
                }
        }
        pp = NULL;
        goto pp_not_found;
pp_found:
        if (!hlist_empty(&pp->owner)) {
                /* We had a port hash table hit - there is an
                 * available port (pp != NULL) and it is being
                 * used by other socket (pp->owner not empty); that other
                 * socket is going to be sk2.
                 */
                int reuse = sk->sk_reuse;
                struct sock *sk2;
                struct hlist_node *node;

                SCTP_DEBUG_PRINTK("sctp_get_port() found a possible match\n");
                if (pp->fastreuse && sk->sk_reuse)
                        goto success;

                /* Run through the list of sockets bound to the port
                 * (pp->port) [via the pointers bind_next and
                 * bind_pprev in the struct sock *sk2 (pp->sk)]. On each one,
                 * we get the endpoint they describe and run through
                 * the endpoint's list of IP (v4 or v6) addresses,
                 * comparing each of the addresses with the address of
                 * the socket sk. If we find a match, then that means
                 * that this port/socket (sk) combination are already
                 * in an endpoint.
                 */
                sk_for_each_bound(sk2, node, &pp->owner) {
                        struct sctp_endpoint *ep2;
                        ep2 = sctp_sk(sk2)->ep;

                        if (reuse && sk2->sk_reuse)
                                continue;

                        if (sctp_bind_addr_match(&ep2->base.bind_addr, addr,
                                                 sctp_sk(sk))) {
                                ret = (long)sk2;
                                goto fail_unlock;
                        }
                }
                SCTP_DEBUG_PRINTK("sctp_get_port(): Found a match\n");
        }
pp_not_found:
        /* If there was a hash table miss, create a new port.  */
        ret = 1;
        if (!pp && !(pp = sctp_bucket_create(head, snum)))
                goto fail_unlock;

        /* In either case (hit or miss), make sure fastreuse is 1 only
         * if sk->sk_reuse is too (that is, if the caller requested
         * SO_REUSEADDR on this socket -sk-).
         */
        if (hlist_empty(&pp->owner))
                pp->fastreuse = sk->sk_reuse ? 1 : 0;
        else if (pp->fastreuse && !sk->sk_reuse)
                pp->fastreuse = 0;

        /* We are set, so fill up all the data in the hash table
         * entry, tie the socket list information with the rest of the
         * sockets FIXME: Blurry, NPI (ipg).
         */
success:
        inet_sk(sk)->num = snum;
        if (!sctp_sk(sk)->bind_hash) {
                sk_add_bind_node(sk, &pp->owner);
                sctp_sk(sk)->bind_hash = pp;
        }
        ret = 0;

fail_unlock:
        sctp_spin_unlock(&head->lock);

fail:
        sctp_local_bh_enable();
        addr->v4.sin_port = htons(addr->v4.sin_port);
        return ret;
}

/* Assign a 'snum' port to the socket.  If snum == 0, an ephemeral
 * port is requested.
 */
static int sctp_get_port(struct sock *sk, unsigned short snum)
{
        long ret;
        union sctp_addr addr;
        struct sctp_af *af = sctp_sk(sk)->pf->af;

        /* Set up a dummy address struct from the sk. */
        af->from_sk(&addr, sk);
        addr.v4.sin_port = htons(snum);

        /* Note: sk->sk_num gets filled in if ephemeral port request. */
        ret = sctp_get_port_local(sk, &addr);

        return (ret ? 1 : 0);
}

/*
 * 3.1.3 listen() - UDP Style Syntax
 *
 *   By default, new associations are not accepted for UDP style sockets.
 *   An application uses listen() to mark a socket as being able to
 *   accept new associations.
 */
SCTP_STATIC int sctp_seqpacket_listen(struct sock *sk, int backlog)
{
        struct sctp_opt *sp = sctp_sk(sk);
        struct sctp_endpoint *ep = sp->ep;

        /* Only UDP style sockets that are not peeled off are allowed to
         * listen().
         */
        if (!sctp_style(sk, UDP))
                return -EINVAL;

        /* If backlog is zero, disable listening. */
        if (!backlog) {
                if (sctp_sstate(sk, CLOSED))
                        return 0;
                
                sctp_unhash_endpoint(ep);
                sk->sk_state = SCTP_SS_CLOSED;
        }

        /* Return if we are already listening. */
        if (sctp_sstate(sk, LISTENING))
                return 0;
                
        /*
         * If a bind() or sctp_bindx() is not called prior to a listen()
         * call that allows new associations to be accepted, the system
         * picks an ephemeral port and will choose an address set equivalent
         * to binding with a wildcard address.
         *
         * This is not currently spelled out in the SCTP sockets
         * extensions draft, but follows the practice as seen in TCP
         * sockets.
         */
        if (!ep->base.bind_addr.port) {
                if (sctp_autobind(sk))
                        return -EAGAIN;
        }
        sk->sk_state = SCTP_SS_LISTENING;
        sctp_hash_endpoint(ep);
        return 0;
}

/*
 * 4.1.3 listen() - TCP Style Syntax
 *
 *   Applications uses listen() to ready the SCTP endpoint for accepting
 *   inbound associations.
 */
SCTP_STATIC int sctp_stream_listen(struct sock *sk, int backlog)
{
        struct sctp_opt *sp = sctp_sk(sk);
        struct sctp_endpoint *ep = sp->ep;

        /* If backlog is zero, disable listening. */
        if (!backlog) {
                if (sctp_sstate(sk, CLOSED))
                        return 0;
                
                sctp_unhash_endpoint(ep);
                sk->sk_state = SCTP_SS_CLOSED;
        }

        if (sctp_sstate(sk, LISTENING))
                return 0;

        /*
         * If a bind() or sctp_bindx() is not called prior to a listen()
         * call that allows new associations to be accepted, the system
         * picks an ephemeral port and will choose an address set equivalent
         * to binding with a wildcard address.
         *
         * This is not currently spelled out in the SCTP sockets
         * extensions draft, but follows the practice as seen in TCP
         * sockets.
         */
        if (!ep->base.bind_addr.port) {
                if (sctp_autobind(sk))
                        return -EAGAIN;
        }
        sk->sk_state = SCTP_SS_LISTENING;
        sk->sk_max_ack_backlog = backlog;
        sctp_hash_endpoint(ep);
        return 0;
}

/*
 *  Move a socket to LISTENING state.
 */
int sctp_inet_listen(struct socket *sock, int backlog)
{
        struct sock *sk = sock->sk;
        struct crypto_tfm *tfm=NULL;
        int err = -EINVAL;

        if (unlikely(backlog < 0))
                goto out;

        sctp_lock_sock(sk);

        if (sock->state != SS_UNCONNECTED)
                goto out;

        /* Allocate HMAC for generating cookie. */
        if (sctp_hmac_alg) {
                tfm = sctp_crypto_alloc_tfm(sctp_hmac_alg, 0);
                if (!tfm) {
                        err = -ENOSYS;
                        goto out;
                }
        }

        switch (sock->type) {
        case SOCK_SEQPACKET:
                err = sctp_seqpacket_listen(sk, backlog);
                break;
        case SOCK_STREAM:
                err = sctp_stream_listen(sk, backlog);
                break;
        default:
                break;
        };
        if (err)
                goto cleanup;

        /* Store away the transform reference. */
        sctp_sk(sk)->hmac = tfm;
out:
        sctp_release_sock(sk);
        return err;
cleanup:
        if (tfm)
                sctp_crypto_free_tfm(tfm);
        goto out;
}

/*
 * This function is done by modeling the current datagram_poll() and the
 * tcp_poll().  Note that, based on these implementations, we don't
 * lock the socket in this function, even though it seems that,
 * ideally, locking or some other mechanisms can be used to ensure
 * the integrity of the counters (sndbuf and wmem_queued) used
 * in this place.  We assume that we don't need locks either until proven
 * otherwise.
 *
 * Another thing to note is that we include the Async I/O support
 * here, again, by modeling the current TCP/UDP code.  We don't have
 * a good way to test with it yet.
 */
unsigned int sctp_poll(struct file *file, struct socket *sock, poll_table *wait)
{
        struct sock *sk = sock->sk;
        struct sctp_opt *sp = sctp_sk(sk);
        unsigned int mask;

        poll_wait(file, sk->sk_sleep, wait);

        /* A TCP-style listening socket becomes readable when the accept queue
         * is not empty.
         */
        if (sctp_style(sk, TCP) && sctp_sstate(sk, LISTENING))
                return (!list_empty(&sp->ep->asocs)) ?
                        (POLLIN | POLLRDNORM) : 0;

        mask = 0;

        /* Is there any exceptional events?  */
        if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
                mask |= POLLERR;
        if (sk->sk_shutdown == SHUTDOWN_MASK)
                mask |= POLLHUP;

        /* Is it readable?  Reconsider this code with TCP-style support.  */
        if (!skb_queue_empty(&sk->sk_receive_queue) ||
            (sk->sk_shutdown & RCV_SHUTDOWN))
                mask |= POLLIN | POLLRDNORM;

        /* The association is either gone or not ready.  */
        if (!sctp_style(sk, UDP) && sctp_sstate(sk, CLOSED))
                return mask;

        /* Is it writable?  */
        if (sctp_writeable(sk)) {
                mask |= POLLOUT | POLLWRNORM;
        } else {
                set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
                /*
                 * Since the socket is not locked, the buffer
                 * might be made available after the writeable check and
                 * before the bit is set.  This could cause a lost I/O
                 * signal.  tcp_poll() has a race breaker for this race
                 * condition.  Based on their implementation, we put
                 * in the following code to cover it as well.
                 */
                if (sctp_writeable(sk))
                        mask |= POLLOUT | POLLWRNORM;
        }
        return mask;
}

/********************************************************************
 * 2nd Level Abstractions
 ********************************************************************/

static struct sctp_bind_bucket *sctp_bucket_create(
        struct sctp_bind_hashbucket *head, unsigned short snum)
{
        struct sctp_bind_bucket *pp;

        pp = kmem_cache_alloc(sctp_bucket_cachep, SLAB_ATOMIC);
        SCTP_DBG_OBJCNT_INC(bind_bucket);
        if (pp) {
                pp->port = snum;
                pp->fastreuse = 0;
                INIT_HLIST_HEAD(&pp->owner);
                if ((pp->next = head->chain) != NULL)
                        pp->next->pprev = &pp->next;
                head->chain = pp;
                pp->pprev = &head->chain;
        }
        return pp;
}

/* Caller must hold hashbucket lock for this tb with local BH disabled */
static void sctp_bucket_destroy(struct sctp_bind_bucket *pp)
{
        if (hlist_empty(&pp->owner)) {
                if (pp->next)
                        pp->next->pprev = pp->pprev;
                *(pp->pprev) = pp->next;
                kmem_cache_free(sctp_bucket_cachep, pp);
                SCTP_DBG_OBJCNT_DEC(bind_bucket);
        }
}

/* Release this socket's reference to a local port.  */
static inline void __sctp_put_port(struct sock *sk)
{
        struct sctp_bind_hashbucket *head =
                &sctp_port_hashtable[sctp_phashfn(inet_sk(sk)->num)];
        struct sctp_bind_bucket *pp;

        sctp_spin_lock(&head->lock);
        pp = sctp_sk(sk)->bind_hash;
        __sk_del_bind_node(sk);
        sctp_sk(sk)->bind_hash = NULL;
        inet_sk(sk)->num = 0;
        sctp_bucket_destroy(pp);
        sctp_spin_unlock(&head->lock);
}

void sctp_put_port(struct sock *sk)
{
        sctp_local_bh_disable();
        __sctp_put_port(sk);
        sctp_local_bh_enable();
}

/*
 * The system picks an ephemeral port and choose an address set equivalent
 * to binding with a wildcard address.
 * One of those addresses will be the primary address for the association.
 * This automatically enables the multihoming capability of SCTP.
 */
static int sctp_autobind(struct sock *sk)
{
        union sctp_addr autoaddr;
        struct sctp_af *af;
        unsigned short port;

        /* Initialize a local sockaddr structure to INADDR_ANY. */
        af = sctp_sk(sk)->pf->af;

        port = htons(inet_sk(sk)->num);
        af->inaddr_any(&autoaddr, port);

        return sctp_do_bind(sk, &autoaddr, af->sockaddr_len);
}

/* Parse out IPPROTO_SCTP CMSG headers.  Perform only minimal validation.
 *
 * From RFC 2292
 * 4.2 The cmsghdr Structure *
 *
 * When ancillary data is sent or received, any number of ancillary data
 * objects can be specified by the msg_control and msg_controllen members of
 * the msghdr structure, because each object is preceded by
 * a cmsghdr structure defining the object's length (the cmsg_len member).
 * Historically Berkeley-derived implementations have passed only one object
 * at a time, but this API allows multiple objects to be
 * passed in a single call to sendmsg() or recvmsg(). The following example
 * shows two ancillary data objects in a control buffer.
 *
 *   |<--------------------------- msg_controllen -------------------------->|
 *   |                                                                       |
 *
 *   |<----- ancillary data object ----->|<----- ancillary data object ----->|
 *
 *   |<---------- CMSG_SPACE() --------->|<---------- CMSG_SPACE() --------->|
 *   |                                   |                                   |
 *
 *   |<---------- cmsg_len ---------->|  |<--------- cmsg_len ----------->|  |
 *
 *   |<--------- CMSG_LEN() --------->|  |<-------- CMSG_LEN() ---------->|  |
 *   |                                |  |                                |  |
 *
 *   +-----+-----+-----+--+-----------+--+-----+-----+-----+--+-----------+--+
 *   |cmsg_|cmsg_|cmsg_|XX|           |XX|cmsg_|cmsg_|cmsg_|XX|           |XX|
 *
 *   |len  |level|type |XX|cmsg_data[]|XX|len  |level|type |XX|cmsg_data[]|XX|
 *
 *   +-----+-----+-----+--+-----------+--+-----+-----+-----+--+-----------+--+
 *    ^
 *    |
 *
 * msg_control
 * points here
 */
SCTP_STATIC int sctp_msghdr_parse(const struct msghdr *msg,
                                  sctp_cmsgs_t *cmsgs)
{
        struct cmsghdr *cmsg;

        for (cmsg = CMSG_FIRSTHDR(msg);
             cmsg != NULL;
             cmsg = CMSG_NXTHDR((struct msghdr*)msg, cmsg)) {
                /* Check for minimum length.  The SCM code has this check.  */
                if (cmsg->cmsg_len < sizeof(struct cmsghdr) ||
                    (unsigned long)(((char*)cmsg - (char*)msg->msg_control)
                                    + cmsg->cmsg_len) > msg->msg_controllen) {
                        return -EINVAL;
                }

                /* Should we parse this header or ignore?  */
                if (cmsg->cmsg_level != IPPROTO_SCTP)
                        continue;

                /* Strictly check lengths following example in SCM code.  */
                switch (cmsg->cmsg_type) {
                case SCTP_INIT:
                        /* SCTP Socket API Extension
                         * 5.2.1 SCTP Initiation Structure (SCTP_INIT)
                         *
                         * This cmsghdr structure provides information for
                         * initializing new SCTP associations with sendmsg().
                         * The SCTP_INITMSG socket option uses this same data
                         * structure.  This structure is not used for
                         * recvmsg().
                         *
                         * cmsg_level    cmsg_type      cmsg_data[]
                         * ------------  ------------   ----------------------
                         * IPPROTO_SCTP  SCTP_INIT      struct sctp_initmsg
                         */
                        if (cmsg->cmsg_len !=
                            CMSG_LEN(sizeof(struct sctp_initmsg)))
                                return -EINVAL;
                        cmsgs->init = (struct sctp_initmsg *)CMSG_DATA(cmsg);
                        break;

                case SCTP_SNDRCV:
                        /* SCTP Socket API Extension
                         * 5.2.2 SCTP Header Information Structure(SCTP_SNDRCV)
                         *
                         * This cmsghdr structure specifies SCTP options for
                         * sendmsg() and describes SCTP header information
                         * about a received message through recvmsg().
                         *
                         * cmsg_level    cmsg_type      cmsg_data[]
                         * ------------  ------------   ----------------------
                         * IPPROTO_SCTP  SCTP_SNDRCV    struct sctp_sndrcvinfo
                         */
                        if (cmsg->cmsg_len !=
                            CMSG_LEN(sizeof(struct sctp_sndrcvinfo)))
                                return -EINVAL;

                        cmsgs->info =
                                (struct sctp_sndrcvinfo *)CMSG_DATA(cmsg);

                        /* Minimally, validate the sinfo_flags. */
                        if (cmsgs->info->sinfo_flags &
                            ~(MSG_UNORDERED | MSG_ADDR_OVER |
                              MSG_ABORT | MSG_EOF))
                                return -EINVAL;
                        break;

                default:
                        return -EINVAL;
                };
        }
        return 0;
}

/*
 * Wait for a packet..
 * Note: This function is the same function as in core/datagram.c
 * with a few modifications to make lksctp work.
 */
static int sctp_wait_for_packet(struct sock * sk, int *err, long *timeo_p)
{
        int error;
        DEFINE_WAIT(wait);

        prepare_to_wait_exclusive(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);

        /* Socket errors? */
        error = sock_error(sk);
        if (error)
                goto out;

        if (!skb_queue_empty(&sk->sk_receive_queue))
                goto ready;

        /* Socket shut down?  */
        if (sk->sk_shutdown & RCV_SHUTDOWN)
                goto out;

        /* Sequenced packets can come disconnected.  If so we report the
         * problem.
         */
        error = -ENOTCONN;

        /* Is there a good reason to think that we may receive some data?  */
        if (list_empty(&sctp_sk(sk)->ep->asocs) && !sctp_sstate(sk, LISTENING))
                goto out;

        /* Handle signals.  */
        if (signal_pending(current))
                goto interrupted;

        /* Let another process have a go.  Since we are going to sleep
         * anyway.  Note: This may cause odd behaviors if the message
         * does not fit in the user's buffer, but this seems to be the
         * only way to honor MSG_DONTWAIT realistically.
         */
        sctp_release_sock(sk);
        *timeo_p = schedule_timeout(*timeo_p);
        sctp_lock_sock(sk);

ready:
        finish_wait(sk->sk_sleep, &wait);
        return 0;

interrupted:
        error = sock_intr_errno(*timeo_p);

out:
        finish_wait(sk->sk_sleep, &wait);
        *err = error;
        return error;
}

/* Receive a datagram.
 * Note: This is pretty much the same routine as in core/datagram.c
 * with a few changes to make lksctp work.
 */
static struct sk_buff *sctp_skb_recv_datagram(struct sock *sk, int flags,
                                              int noblock, int *err)
{
        int error;
        struct sk_buff *skb;
        long timeo;

        /* Caller is allowed not to check sk->sk_err before calling.  */
        error = sock_error(sk);
        if (error)
                goto no_packet;

        timeo = sock_rcvtimeo(sk, noblock);

        SCTP_DEBUG_PRINTK("Timeout: timeo: %ld, MAX: %ld.\n",
                          timeo, MAX_SCHEDULE_TIMEOUT);

        do {
                /* Again only user level code calls this function,
                 * so nothing interrupt level
                 * will suddenly eat the receive_queue.
                 *
                 *  Look at current nfs client by the way...
                 *  However, this function was corrent in any case. 8)
                 */
                if (flags & MSG_PEEK) {
                        unsigned long cpu_flags;

                        sctp_spin_lock_irqsave(&sk->sk_receive_queue.lock,
                                               cpu_flags);
                        skb = skb_peek(&sk->sk_receive_queue);
                        if (skb)
                                atomic_inc(&skb->users);
                        sctp_spin_unlock_irqrestore(&sk->sk_receive_queue.lock,
                                                    cpu_flags);
                } else {
                        skb = skb_dequeue(&sk->sk_receive_queue);
                }

                if (skb)
                        return skb;

                if (sk->sk_shutdown & RCV_SHUTDOWN)
                        break;

                /* User doesn't want to wait.  */
                error = -EAGAIN;
                if (!timeo)
                        goto no_packet;
        } while (sctp_wait_for_packet(sk, err, &timeo) == 0);

        return NULL;

no_packet:
        *err = error;
        return NULL;
}

/* 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;
}

/* 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;

        amt = sk->sk_sndbuf - asoc->sndbuf_used;
        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);

        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);
        sk->sk_wmem_queued += SCTP_DATA_SNDSIZE(chunk);
}

/* If sndbuf has changed, wake up per association sndbuf waiters.  */
static void __sctp_write_space(struct sctp_association *asoc)
{
        struct sock *sk = asoc->base.sk;
        struct socket *sock = sk->sk_socket;

        if ((sctp_wspace(asoc) > 0) && sock) {
                if (waitqueue_active(&asoc->wait))
                        wake_up_interruptible(&asoc->wait);

                if (sctp_writeable(sk)) {
                        if (sk->sk_sleep && waitqueue_active(sk->sk_sleep))
                                wake_up_interruptible(sk->sk_sleep);

                        /* Note that we try to include the Async I/O support
                         * here by modeling from the current TCP/UDP code.
                         * We have not tested with it yet.
                         */
                        if (sock->fasync_list &&
                            !(sk->sk_shutdown & SEND_SHUTDOWN))
                                sock_wake_async(sock, 2, POLL_OUT);
                }
        }
}

/* Do accounting for the sndbuf space.
 * Decrement the used sndbuf space of the corresponding association by the
 * data size which was just transmitted(freed).
 */
static void sctp_wfree(struct sk_buff *skb)
{
        struct sctp_association *asoc;
        struct sctp_chunk *chunk;
        struct sock *sk;

        /* Get the saved chunk pointer.  */
        chunk = *((struct sctp_chunk **)(skb->cb));
        asoc = chunk->asoc;
        sk = asoc->base.sk;
        asoc->sndbuf_used -= SCTP_DATA_SNDSIZE(chunk);
        sk->sk_wmem_queued -= SCTP_DATA_SNDSIZE(chunk);
        __sctp_write_space(asoc);

        sctp_association_put(asoc);
}

/* Helper function to wait for space in the sndbuf.  */
static int sctp_wait_for_sndbuf(struct sctp_association *asoc, long *timeo_p,
                                size_t msg_len)
{
        struct sock *sk = asoc->base.sk;
        int err = 0;
        long current_timeo = *timeo_p;
        DEFINE_WAIT(wait);

        SCTP_DEBUG_PRINTK("wait_for_sndbuf: asoc=%p, timeo=%ld, msg_len=%zu\n",
                          asoc, (long)(*timeo_p), msg_len);

        /* Increment the association's refcnt.  */
        sctp_association_hold(asoc);

        /* Wait on the association specific sndbuf space. */
        for (;;) {
                prepare_to_wait_exclusive(&asoc->wait, &wait,
                                          TASK_INTERRUPTIBLE);
                if (!*timeo_p)
                        goto do_nonblock;
                if (sk->sk_err || asoc->state >= SCTP_STATE_SHUTDOWN_PENDING ||
                    asoc->base.dead)
                        goto do_error;
                if (signal_pending(current))
                        goto do_interrupted;
                if (msg_len <= sctp_wspace(asoc))
                        break;

                /* Let another process have a go.  Since we are going
                 * to sleep anyway.
                 */
                sctp_release_sock(sk);
                current_timeo = schedule_timeout(current_timeo);
                sctp_lock_sock(sk);

                *timeo_p = current_timeo;
        }

out:
        finish_wait(&asoc->wait, &wait);

        /* Release the association's refcnt.  */
        sctp_association_put(asoc);

        return err;

do_error:
        err = -EPIPE;
        goto out;

do_interrupted:
        err = sock_intr_errno(*timeo_p);
        goto out;

do_nonblock:
        err = -EAGAIN;
        goto out;
}

/* If socket sndbuf has changed, wake up all per association waiters.  */
void sctp_write_space(struct sock *sk)
{
        struct sctp_association *asoc;
        struct list_head *pos;

        /* Wake up the tasks in each wait queue.  */
        list_for_each(pos, &((sctp_sk(sk))->ep->asocs)) {
                asoc = list_entry(pos, struct sctp_association, asocs);
                __sctp_write_space(asoc);
        }
}

/* Is there any sndbuf space available on the socket?
 *
 * Note that wmem_queued is the sum of the send buffers on all of the
 * associations on the same socket.  For a UDP-style socket with
 * multiple associations, it is possible for it to be "unwriteable"
 * prematurely.  I assume that this is acceptable because
 * a premature "unwriteable" is better than an accidental "writeable" which
 * would cause an unwanted block under certain circumstances.  For the 1-1
 * UDP-style sockets or TCP-style sockets, this code should work.
 *  - Daisy
 */
static int sctp_writeable(struct sock *sk)
{
        int amt = 0;

        amt = sk->sk_sndbuf - sk->sk_wmem_queued;
        if (amt < 0)
                amt = 0;
        return amt;
}

/* Wait for an association to go into ESTABLISHED state. If timeout is 0,
 * returns immediately with EINPROGRESS.
 */
static int sctp_wait_for_connect(struct sctp_association *asoc, long *timeo_p)
{
        struct sock *sk = asoc->base.sk;
        int err = 0;
        long current_timeo = *timeo_p;
        DEFINE_WAIT(wait);

        SCTP_DEBUG_PRINTK("%s: asoc=%p, timeo=%ld\n", __FUNCTION__, asoc,
                          (long)(*timeo_p));

        /* Increment the association's refcnt.  */
        sctp_association_hold(asoc);

        for (;;) {
                prepare_to_wait_exclusive(&asoc->wait, &wait,
                                          TASK_INTERRUPTIBLE);
                if (!*timeo_p)
                        goto do_nonblock;
                if (sk->sk_shutdown & RCV_SHUTDOWN)
                        break;
                if (sk->sk_err || asoc->state >= SCTP_STATE_SHUTDOWN_PENDING ||
                    asoc->base.dead)
                        goto do_error;
                if (signal_pending(current))
                        goto do_interrupted;

                if (sctp_state(asoc, ESTABLISHED))
                        break;

                /* Let another process have a go.  Since we are going
                 * to sleep anyway.
                 */
                sctp_release_sock(sk);
                current_timeo = schedule_timeout(current_timeo);
                sctp_lock_sock(sk);

                *timeo_p = current_timeo;
        }

out:
        finish_wait(&asoc->wait, &wait);

        /* Release the association's refcnt.  */
        sctp_association_put(asoc);

        return err;

do_error:
        err = -ECONNREFUSED;
        goto out;

do_interrupted:
        err = sock_intr_errno(*timeo_p);
        goto out;

do_nonblock:
        err = -EINPROGRESS;
        goto out;
}

static int sctp_wait_for_accept(struct sock *sk, long timeo)
{
        struct sctp_endpoint *ep;
        int err = 0;
        DEFINE_WAIT(wait);

        ep = sctp_sk(sk)->ep;


        for (;;) {
                prepare_to_wait_exclusive(sk->sk_sleep, &wait,
                                          TASK_INTERRUPTIBLE);

                if (list_empty(&ep->asocs)) {
                        sctp_release_sock(sk);
                        timeo = schedule_timeout(timeo);
                        sctp_lock_sock(sk);
                }

                err = -EINVAL;
                if (!sctp_sstate(sk, LISTENING))
                        break;

                err = 0;
                if (!list_empty(&ep->asocs))
                        break;

                err = sock_intr_errno(timeo);
                if (signal_pending(current))
                        break;

                err = -EAGAIN;
                if (!timeo)
                        break;
        }

        finish_wait(sk->sk_sleep, &wait);

        return err;
}

void sctp_wait_for_close(struct sock *sk, long timeout)
{
        DEFINE_WAIT(wait);

        do {
                prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
                if (list_empty(&sctp_sk(sk)->ep->asocs))
                        break;
                sctp_release_sock(sk);
                timeout = schedule_timeout(timeout);
                sctp_lock_sock(sk);
        } while (!signal_pending(current) && timeout);

        finish_wait(sk->sk_sleep, &wait);
}

/* Populate the fields of the newsk from the oldsk and migrate the assoc
 * and its messages to the newsk.
 */
static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
                              struct sctp_association *assoc,
                              sctp_socket_type_t type)
{
        struct sctp_opt *oldsp = sctp_sk(oldsk);
        struct sctp_opt *newsp = sctp_sk(newsk);
        struct sctp_bind_bucket *pp; /* hash list port iterator */
        struct sctp_endpoint *newep = newsp->ep;
        struct sk_buff *skb, *tmp;
        struct sctp_ulpevent *event;

        /* Migrate socket buffer sizes and all the socket level options to the
         * new socket.
         */
        newsk->sk_sndbuf = oldsk->sk_sndbuf;
        newsk->sk_rcvbuf = oldsk->sk_rcvbuf;
        /* Brute force copy old sctp opt. */
        memcpy(newsp, oldsp, sizeof(struct sctp_opt));

        /* Restore the ep value that was overwritten with the above structure
         * copy.
         */
        newsp->ep = newep;
        newsp->hmac = NULL;

        /* Hook this new socket in to the bind_hash list. */
        pp = sctp_sk(oldsk)->bind_hash;
        sk_add_bind_node(newsk, &pp->owner);
        sctp_sk(newsk)->bind_hash = pp;
        inet_sk(newsk)->num = inet_sk(oldsk)->num;

        /* Move any messages in the old socket's receive queue that are for the
         * peeled off association to the new socket's receive queue.
         */
        sctp_skb_for_each(skb, &oldsk->sk_receive_queue, tmp) {
                event = sctp_skb2event(skb);
                if (event->asoc == assoc) {
                        __skb_unlink(skb, skb->list);
                        __skb_queue_tail(&newsk->sk_receive_queue, skb);
                }
        }

        /* Clean up any messages pending delivery due to partial
         * delivery.   Three cases:
         * 1) No partial deliver;  no work.
         * 2) Peeling off partial delivery; keep pd_lobby in new pd_lobby.
         * 3) Peeling off non-partial delivery; move pd_lobby to recieve_queue.
         */
        skb_queue_head_init(&newsp->pd_lobby);
        sctp_sk(newsk)->pd_mode = assoc->ulpq.pd_mode;

        if (sctp_sk(oldsk)->pd_mode) {
                struct sk_buff_head *queue;

                /* Decide which queue to move pd_lobby skbs to. */
                if (assoc->ulpq.pd_mode) {
                        queue = &newsp->pd_lobby;
                } else
                        queue = &newsk->sk_receive_queue;

                /* Walk through the pd_lobby, looking for skbs that
                 * need moved to the new socket.
                 */
                sctp_skb_for_each(skb, &oldsp->pd_lobby, tmp) {
                        event = sctp_skb2event(skb);
                        if (event->asoc == assoc) {
                                __skb_unlink(skb, skb->list);
                                __skb_queue_tail(queue, skb);
                        }
                }

                /* Clear up any skbs waiting for the partial
                 * delivery to finish.
                 */
                if (assoc->ulpq.pd_mode)
                        sctp_clear_pd(oldsk);

        }

        /* Set the type of socket to indicate that it is peeled off from the
         * original UDP-style socket or created with the accept() call on a
         * TCP-style socket..
         */
        newsp->type = type;

        /* Migrate the association to the new socket. */
        sctp_assoc_migrate(assoc, newsk);

        /* If the association on the newsk is already closed before accept()
         * is called, set RCV_SHUTDOWN flag.
         */
        if (sctp_state(assoc, CLOSED) && sctp_style(newsk, TCP))
                newsk->sk_shutdown |= RCV_SHUTDOWN;

        newsk->sk_state = SCTP_SS_ESTABLISHED;
}

/* This proto struct describes the ULP interface for SCTP.  */
struct proto sctp_prot = {
        .name        =  "SCTP",
        .close       =  sctp_close,
        .connect     =  sctp_connect,
        .disconnect  =  sctp_disconnect,
        .accept      =  sctp_accept,
        .ioctl       =  sctp_ioctl,
        .init        =  sctp_init_sock,
        .destroy     =  sctp_destroy_sock,
        .shutdown    =  sctp_shutdown,
        .setsockopt  =  sctp_setsockopt,
        .getsockopt  =  sctp_getsockopt,
        .sendmsg     =  sctp_sendmsg,
        .recvmsg     =  sctp_recvmsg,
        .bind        =  sctp_bind,
        .backlog_rcv =  sctp_backlog_rcv,
        .hash        =  sctp_hash,
        .unhash      =  sctp_unhash,
        .get_port    =  sctp_get_port,
};