text: /*
   * net/tipc/socket.c: TIPC socket API
   *
   * Copyright (c) 2001-2007, Ericsson AB
   * Copyright (c) 2004-2008, Wind River Systems
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the names of the copyright holders nor the names of its
   *    contributors may be used to endorse or promote products derived from
   *    this software without specific prior written permission.
   *
   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL") version 2 as published by the Free
   * Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/net.h>
  #include <linux/socket.h>
  #include <linux/errno.h>
  #include <linux/mm.h>
  #include <linux/poll.h>
  #include <linux/fcntl.h>
  #include <linux/gfp.h>
  #include <asm/string.h>
  #include <asm/atomic.h>
  #include <net/sock.h>
  
  #include <linux/tipc.h>
  #include <linux/tipc_config.h>
  #include <net/tipc/tipc_msg.h>
  #include <net/tipc/tipc_port.h>
  
  #include "core.h"
  
  #define SS_LISTENING	-1	/* socket is listening */
  #define SS_READY	-2	/* socket is connectionless */
  
  #define OVERLOAD_LIMIT_BASE	5000
  #define CONN_TIMEOUT_DEFAULT	8000	/* default connect timeout = 8s */
  
  struct tipc_sock {
  	struct sock sk;
  	struct tipc_port *p;
  	struct tipc_portid peer_name;
  };
  
  #define tipc_sk(sk) ((struct tipc_sock *)(sk))
  #define tipc_sk_port(sk) ((struct tipc_port *)(tipc_sk(sk)->p))
  
  static int backlog_rcv(struct sock *sk, struct sk_buff *skb);
  static u32 dispatch(struct tipc_port *tport, struct sk_buff *buf);
  static void wakeupdispatch(struct tipc_port *tport);
  
  static const struct proto_ops packet_ops;
  static const struct proto_ops stream_ops;
  static const struct proto_ops msg_ops;
  
  static struct proto tipc_proto;
  
  static int sockets_enabled = 0;
  
  static atomic_t tipc_queue_size = ATOMIC_INIT(0);
  
  /*
   * Revised TIPC socket locking policy:
   *
   * Most socket operations take the standard socket lock when they start
   * and hold it until they finish (or until they need to sleep).  Acquiring
   * this lock grants the owner exclusive access to the fields of the socket
   * data structures, with the exception of the backlog queue.  A few socket
   * operations can be done without taking the socket lock because they only
   * read socket information that never changes during the life of the socket.
   *
   * Socket operations may acquire the lock for the associated TIPC port if they
   * need to perform an operation on the port.  If any routine needs to acquire
   * both the socket lock and the port lock it must take the socket lock first
   * to avoid the risk of deadlock.
   *
   * The dispatcher handling incoming messages cannot grab the socket lock in
   * the standard fashion, since invoked it runs at the BH level and cannot block.
   * Instead, it checks to see if the socket lock is currently owned by someone,
   * and either handles the message itself or adds it to the socket's backlog
   * queue; in the latter case the queued message is processed once the process
   * owning the socket lock releases it.
   *
   * NOTE: Releasing the socket lock while an operation is sleeping overcomes
   * the problem of a blocked socket operation preventing any other operations
   * from occurring.  However, applications must be careful if they have
   * multiple threads trying to send (or receive) on the same socket, as these
   * operations might interfere with each other.  For example, doing a connect
   * and a receive at the same time might allow the receive to consume the
   * ACK message meant for the connect.  While additional work could be done
   * to try and overcome this, it doesn't seem to be worthwhile at the present.
   *
   * NOTE: Releasing the socket lock while an operation is sleeping also ensures
   * that another operation that must be performed in a non-blocking manner is
   * not delayed for very long because the lock has already been taken.
   *
   * NOTE: This code assumes that certain fields of a port/socket pair are
   * constant over its lifetime; such fields can be examined without taking
   * the socket lock and/or port lock, and do not need to be re-read even
   * after resuming processing after waiting.  These fields include:
   *   - socket type
   *   - pointer to socket sk structure (aka tipc_sock structure)
   *   - pointer to port structure
   *   - port reference
   */
  
  /**
   * advance_rx_queue - discard first buffer in socket receive queue
   *
   * Caller must hold socket lock
   */
  
  static void advance_rx_queue(struct sock *sk)
  {
  	buf_discard(__skb_dequeue(&sk->sk_receive_queue));
  	atomic_dec(&tipc_queue_size);
  }
  
  /**
   * discard_rx_queue - discard all buffers in socket receive queue
   *
   * Caller must hold socket lock
   */
  
  static void discard_rx_queue(struct sock *sk)
  {
  	struct sk_buff *buf;
  
  	while ((buf = __skb_dequeue(&sk->sk_receive_queue))) {
  		atomic_dec(&tipc_queue_size);
  		buf_discard(buf);
  	}
  }
  
  /**
   * reject_rx_queue - reject all buffers in socket receive queue
   *
   * Caller must hold socket lock
   */
  
  static void reject_rx_queue(struct sock *sk)
  {
  	struct sk_buff *buf;
  
  	while ((buf = __skb_dequeue(&sk->sk_receive_queue))) {
  		tipc_reject_msg(buf, TIPC_ERR_NO_PORT);
  		atomic_dec(&tipc_queue_size);
  	}
  }
  
  /**
   * tipc_create - create a TIPC socket
   * @net: network namespace (must be default network)
   * @sock: pre-allocated socket structure
   * @protocol: protocol indicator (must be 0)
   * @kern: caused by kernel or by userspace?
   *
   * This routine creates additional data structures used by the TIPC socket,
   * initializes them, and links them together.
   *
   * Returns 0 on success, errno otherwise
   */
  
  static int tipc_create(struct net *net, struct socket *sock, int protocol,
  		       int kern)
  {
  	const struct proto_ops *ops;
  	socket_state state;
  	struct sock *sk;
  	struct tipc_port *tp_ptr;
  
  	/* Validate arguments */
  
  	if (!net_eq(net, &init_net))
  		return -EAFNOSUPPORT;
  
  	if (unlikely(protocol != 0))
  		return -EPROTONOSUPPORT;
  
  	switch (sock->type) {
  	case SOCK_STREAM:
  		ops = &stream_ops;
  		state = SS_UNCONNECTED;
  		break;
  	case SOCK_SEQPACKET:
  		ops = &packet_ops;
  		state = SS_UNCONNECTED;
  		break;
  	case SOCK_DGRAM:
  	case SOCK_RDM:
  		ops = &msg_ops;
  		state = SS_READY;
  		break;
  	default:
  		return -EPROTOTYPE;
  	}
  
  	/* Allocate socket's protocol area */
  
  	sk = sk_alloc(net, AF_TIPC, GFP_KERNEL, &tipc_proto);
  	if (sk == NULL)
  		return -ENOMEM;
  
  	/* Allocate TIPC port for socket to use */
  
  	tp_ptr = tipc_createport_raw(sk, &dispatch, &wakeupdispatch,
  				     TIPC_LOW_IMPORTANCE);
  	if (unlikely(!tp_ptr)) {
  		sk_free(sk);
  		return -ENOMEM;
  	}
  
  	/* Finish initializing socket data structures */
  
  	sock->ops = ops;
  	sock->state = state;
  
  	sock_init_data(sock, sk);
  	sk->sk_rcvtimeo = msecs_to_jiffies(CONN_TIMEOUT_DEFAULT);
  	sk->sk_backlog_rcv = backlog_rcv;
  	tipc_sk(sk)->p = tp_ptr;
  
  	spin_unlock_bh(tp_ptr->lock);
  
  	if (sock->state == SS_READY) {
  		tipc_set_portunreturnable(tp_ptr->ref, 1);
  		if (sock->type == SOCK_DGRAM)
  			tipc_set_portunreliable(tp_ptr->ref, 1);
  	}
  
  	atomic_inc(&tipc_user_count);
  	return 0;
  }
  
  /**
   * release - destroy a TIPC socket
   * @sock: socket to destroy
   *
   * This routine cleans up any messages that are still queued on the socket.
   * For DGRAM and RDM socket types, all queued messages are rejected.
   * For SEQPACKET and STREAM socket types, the first message is rejected
   * and any others are discarded.  (If the first message on a STREAM socket
   * is partially-read, it is discarded and the next one is rejected instead.)
   *
   * NOTE: Rejected messages are not necessarily returned to the sender!  They
   * are returned or discarded according to the "destination droppable" setting
   * specified for the message by the sender.
   *
   * Returns 0 on success, errno otherwise
   */
  
  static int release(struct socket *sock)
  {
  	struct sock *sk = sock->sk;
  	struct tipc_port *tport;
  	struct sk_buff *buf;
  	int res;
  
  	/*
  	 * Exit if socket isn't fully initialized (occurs when a failed accept()
  	 * releases a pre-allocated child socket that was never used)
  	 */
  
  	if (sk == NULL)
  		return 0;
  
  	tport = tipc_sk_port(sk);
  	lock_sock(sk);
  
  	/*
  	 * Reject all unreceived messages, except on an active connection
  	 * (which disconnects locally & sends a 'FIN+' to peer)
  	 */
  
  	while (sock->state != SS_DISCONNECTING) {
  		buf = __skb_dequeue(&sk->sk_receive_queue);
  		if (buf == NULL)
  			break;
  		atomic_dec(&tipc_queue_size);
  		if (TIPC_SKB_CB(buf)->handle != msg_data(buf_msg(buf)))
  			buf_discard(buf);
  		else {
  			if ((sock->state == SS_CONNECTING) ||
  			    (sock->state == SS_CONNECTED)) {
  				sock->state = SS_DISCONNECTING;
  				tipc_disconnect(tport->ref);
  			}
  			tipc_reject_msg(buf, TIPC_ERR_NO_PORT);
  		}
  	}
  
  	/*
  	 * Delete TIPC port; this ensures no more messages are queued
  	 * (also disconnects an active connection & sends a 'FIN-' to peer)
  	 */
  
  	res = tipc_deleteport(tport->ref);
  
  	/* Discard any remaining (connection-based) messages in receive queue */
  
  	discard_rx_queue(sk);
  
  	/* Reject any messages that accumulated in backlog queue */
  
  	sock->state = SS_DISCONNECTING;
  	release_sock(sk);
  
  	sock_put(sk);
  	sock->sk = NULL;
  
  	atomic_dec(&tipc_user_count);
  	return res;
  }
  
  /**
   * bind - associate or disassocate TIPC name(s) with a socket
   * @sock: socket structure
   * @uaddr: socket address describing name(s) and desired operation
   * @uaddr_len: size of socket address data structure
   *
   * Name and name sequence binding is indicated using a positive scope value;
   * a negative scope value unbinds the specified name.  Specifying no name
   * (i.e. a socket address length of 0) unbinds all names from the socket.
   *
   * Returns 0 on success, errno otherwise
   *
   * NOTE: This routine doesn't need to take the socket lock since it doesn't
   *       access any non-constant socket information.
   */
  
  static int bind(struct socket *sock, struct sockaddr *uaddr, int uaddr_len)
  {
  	struct sockaddr_tipc *addr = (struct sockaddr_tipc *)uaddr;
  	u32 portref = tipc_sk_port(sock->sk)->ref;
  
  	if (unlikely(!uaddr_len))
  		return tipc_withdraw(portref, 0, NULL);
  
  	if (uaddr_len < sizeof(struct sockaddr_tipc))
  		return -EINVAL;
  	if (addr->family != AF_TIPC)
  		return -EAFNOSUPPORT;
  
  	if (addr->addrtype == TIPC_ADDR_NAME)
  		addr->addr.nameseq.upper = addr->addr.nameseq.lower;
  	else if (addr->addrtype != TIPC_ADDR_NAMESEQ)
  		return -EAFNOSUPPORT;
  
  	return (addr->scope > 0) ?
  		tipc_publish(portref, addr->scope, &addr->addr.nameseq) :
  		tipc_withdraw(portref, -addr->scope, &addr->addr.nameseq);
  }
  
  /**
   * get_name - get port ID of socket or peer socket
   * @sock: socket structure
   * @uaddr: area for returned socket address
   * @uaddr_len: area for returned length of socket address
   * @peer: 0 = own ID, 1 = current peer ID, 2 = current/former peer ID
   *
   * Returns 0 on success, errno otherwise
   *
   * NOTE: This routine doesn't need to take the socket lock since it only
   *       accesses socket information that is unchanging (or which changes in
   * 	 a completely predictable manner).
   */
  
  static int get_name(struct socket *sock, struct sockaddr *uaddr,
  		    int *uaddr_len, int peer)
  {
  	struct sockaddr_tipc *addr = (struct sockaddr_tipc *)uaddr;
  	struct tipc_sock *tsock = tipc_sk(sock->sk);
  
  	if (peer) {
  		if ((sock->state != SS_CONNECTED) &&
  			((peer != 2) || (sock->state != SS_DISCONNECTING)))
  			return -ENOTCONN;
  		addr->addr.id.ref = tsock->peer_name.ref;
  		addr->addr.id.node = tsock->peer_name.node;
  	} else {
  		tipc_ownidentity(tsock->p->ref, &addr->addr.id);
  	}
  
  	*uaddr_len = sizeof(*addr);
  	addr->addrtype = TIPC_ADDR_ID;
  	addr->family = AF_TIPC;
  	addr->scope = 0;
  	addr->addr.name.domain = 0;
  
  	return 0;
  }
  
  /**
   * poll - read and possibly block on pollmask
   * @file: file structure associated with the socket
   * @sock: socket for which to calculate the poll bits
   * @wait: ???
   *
   * Returns pollmask value
   *
   * COMMENTARY:
   * It appears that the usual socket locking mechanisms are not useful here
   * since the pollmask info is potentially out-of-date the moment this routine
   * exits.  TCP and other protocols seem to rely on higher level poll routines
   * to handle any preventable race conditions, so TIPC will do the same ...
   *
   * TIPC sets the returned events as follows:
   * a) POLLRDNORM and POLLIN are set if the socket's receive queue is non-empty
   *    or if a connection-oriented socket is does not have an active connection
   *    (i.e. a read operation will not block).
   * b) POLLOUT is set except when a socket's connection has been terminated
   *    (i.e. a write operation will not block).
   * c) POLLHUP is set when a socket's connection has been terminated.
   *
   * IMPORTANT: The fact that a read or write operation will not block does NOT
   * imply that the operation will succeed!
   */
  
  static unsigned int poll(struct file *file, struct socket *sock,
  			 poll_table *wait)
  {
  	struct sock *sk = sock->sk;
  	u32 mask;
  
  	poll_wait(file, sk_sleep(sk), wait);
  
  	if (!skb_queue_empty(&sk->sk_receive_queue) ||
  	    (sock->state == SS_UNCONNECTED) ||
  	    (sock->state == SS_DISCONNECTING))
  		mask = (POLLRDNORM | POLLIN);
  	else
  		mask = 0;
  
  	if (sock->state == SS_DISCONNECTING)
  		mask |= POLLHUP;
  	else
  		mask |= POLLOUT;
  
  	return mask;
  }
  
  /**
   * dest_name_check - verify user is permitted to send to specified port name
   * @dest: destination address
   * @m: descriptor for message to be sent
   *
   * Prevents restricted configuration commands from being issued by
   * unauthorized users.
   *
   * Returns 0 if permission is granted, otherwise errno
   */
  
  static int dest_name_check(struct sockaddr_tipc *dest, struct msghdr *m)
  {
  	struct tipc_cfg_msg_hdr hdr;
  
  	if (likely(dest->addr.name.name.type >= TIPC_RESERVED_TYPES))
  		return 0;
  	if (likely(dest->addr.name.name.type == TIPC_TOP_SRV))
  		return 0;
  	if (likely(dest->addr.name.name.type != TIPC_CFG_SRV))
  		return -EACCES;
  
  	if (copy_from_user(&hdr, m->msg_iov[0].iov_base, sizeof(hdr)))
  		return -EFAULT;
  	if ((ntohs(hdr.tcm_type) & 0xC000) && (!capable(CAP_NET_ADMIN)))
  		return -EACCES;
  
  	return 0;
  }
  
  /**
   * send_msg - send message in connectionless manner
   * @iocb: if NULL, indicates that socket lock is already held
   * @sock: socket structure
   * @m: message to send
   * @total_len: length of message
   *
   * Message must have an destination specified explicitly.
   * Used for SOCK_RDM and SOCK_DGRAM messages,
   * and for 'SYN' messages on SOCK_SEQPACKET and SOCK_STREAM connections.
   * (Note: 'SYN+' is prohibited on SOCK_STREAM.)
   *
   * Returns the number of bytes sent on success, or errno otherwise
   */
  
  static int send_msg(struct kiocb *iocb, struct socket *sock,
  		    struct msghdr *m, size_t total_len)
  {
  	struct sock *sk = sock->sk;
  	struct tipc_port *tport = tipc_sk_port(sk);
  	struct sockaddr_tipc *dest = (struct sockaddr_tipc *)m->msg_name;
  	int needs_conn;
  	int res = -EINVAL;
  
  	if (unlikely(!dest))
  		return -EDESTADDRREQ;
  	if (unlikely((m->msg_namelen < sizeof(*dest)) ||
  		     (dest->family != AF_TIPC)))
  		return -EINVAL;
  
  	if (iocb)
  		lock_sock(sk);
  
  	needs_conn = (sock->state != SS_READY);
  	if (unlikely(needs_conn)) {
  		if (sock->state == SS_LISTENING) {
  			res = -EPIPE;
  			goto exit;
  		}
  		if (sock->state != SS_UNCONNECTED) {
  			res = -EISCONN;
  			goto exit;
  		}
  		if ((tport->published) ||
  		    ((sock->type == SOCK_STREAM) && (total_len != 0))) {
  			res = -EOPNOTSUPP;
  			goto exit;
  		}
  		if (dest->addrtype == TIPC_ADDR_NAME) {
  			tport->conn_type = dest->addr.name.name.type;
  			tport->conn_instance = dest->addr.name.name.instance;
  		}
  
  		/* Abort any pending connection attempts (very unlikely) */
  
  		reject_rx_queue(sk);
  	}
  
  	do {
  		if (dest->addrtype == TIPC_ADDR_NAME) {
  			if ((res = dest_name_check(dest, m)))
  				break;
  			res = tipc_send2name(tport->ref,
  					     &dest->addr.name.name,
  					     dest->addr.name.domain,
  					     m->msg_iovlen,
  					     m->msg_iov);
  		}
  		else if (dest->addrtype == TIPC_ADDR_ID) {
  			res = tipc_send2port(tport->ref,
  					     &dest->addr.id,
  					     m->msg_iovlen,
  					     m->msg_iov);
  		}
  		else if (dest->addrtype == TIPC_ADDR_MCAST) {
  			if (needs_conn) {
  				res = -EOPNOTSUPP;
  				break;
  			}
  			if ((res = dest_name_check(dest, m)))
  				break;
  			res = tipc_multicast(tport->ref,
  					     &dest->addr.nameseq,
  					     0,
  					     m->msg_iovlen,
  					     m->msg_iov);
  		}
  		if (likely(res != -ELINKCONG)) {
  			if (needs_conn && (res >= 0)) {
  				sock->state = SS_CONNECTING;
  			}
  			break;
  		}
  		if (m->msg_flags & MSG_DONTWAIT) {
  			res = -EWOULDBLOCK;
  			break;
  		}
  		release_sock(sk);
  		res = wait_event_interruptible(*sk_sleep(sk),
  					       !tport->congested);
  		lock_sock(sk);
  		if (res)
  			break;
  	} while (1);
  
  exit:
  	if (iocb)
  		release_sock(sk);
  	return res;
  }
  
  /**
   * send_packet - send a connection-oriented message
   * @iocb: if NULL, indicates that socket lock is already held
   * @sock: socket structure
   * @m: message to send
   * @total_len: length of message
   *
   * Used for SOCK_SEQPACKET messages and SOCK_STREAM data.
   *
   * Returns the number of bytes sent on success, or errno otherwise
   */
  
  static int send_packet(struct kiocb *iocb, struct socket *sock,
  		       struct msghdr *m, size_t total_len)
  {
  	struct sock *sk = sock->sk;
  	struct tipc_port *tport = tipc_sk_port(sk);
  	struct sockaddr_tipc *dest = (struct sockaddr_tipc *)m->msg_name;
  	int res;
  
  	/* Handle implied connection establishment */
  
  	if (unlikely(dest))
  		return send_msg(iocb, sock, m, total_len);
  
  	if (iocb)
  		lock_sock(sk);
  
  	do {
  		if (unlikely(sock->state != SS_CONNECTED)) {
  			if (sock->state == SS_DISCONNECTING)
  				res = -EPIPE;
  			else
  				res = -ENOTCONN;
  			break;
  		}
  
  		res = tipc_send(tport->ref, m->msg_iovlen, m->msg_iov);
  		if (likely(res != -ELINKCONG)) {
  			break;
  		}
  		if (m->msg_flags & MSG_DONTWAIT) {
  			res = -EWOULDBLOCK;
  			break;
  		}
  		release_sock(sk);
  		res = wait_event_interruptible(*sk_sleep(sk),
  			(!tport->congested || !tport->connected));
  		lock_sock(sk);
  		if (res)
  			break;
  	} while (1);
  
  	if (iocb)
  		release_sock(sk);
  	return res;
  }
  
  /**
   * send_stream - send stream-oriented data
   * @iocb: (unused)
   * @sock: socket structure
   * @m: data to send
   * @total_len: total length of data to be sent
   *
   * Used for SOCK_STREAM data.
   *
   * Returns the number of bytes sent on success (or partial success),
   * or errno if no data sent
   */
  
  static int send_stream(struct kiocb *iocb, struct socket *sock,
  		       struct msghdr *m, size_t total_len)
  {
  	struct sock *sk = sock->sk;
  	struct tipc_port *tport = tipc_sk_port(sk);
  	struct msghdr my_msg;
  	struct iovec my_iov;
  	struct iovec *curr_iov;
  	int curr_iovlen;
  	char __user *curr_start;
  	u32 hdr_size;
  	int curr_left;
  	int bytes_to_send;
  	int bytes_sent;
  	int res;
  
  	lock_sock(sk);
  
  	/* Handle special cases where there is no connection */
  
  	if (unlikely(sock->state != SS_CONNECTED)) {
  		if (sock->state == SS_UNCONNECTED) {
  			res = send_packet(NULL, sock, m, total_len);
  			goto exit;
  		} else if (sock->state == SS_DISCONNECTING) {
  			res = -EPIPE;
  			goto exit;
  		} else {
  			res = -ENOTCONN;
  			goto exit;
  		}
  	}
  
  	if (unlikely(m->msg_name)) {
  		res = -EISCONN;
  		goto exit;
  	}
  
  	/*
  	 * Send each iovec entry using one or more messages
  	 *
  	 * Note: This algorithm is good for the most likely case
  	 * (i.e. one large iovec entry), but could be improved to pass sets
  	 * of small iovec entries into send_packet().
  	 */
  
  	curr_iov = m->msg_iov;
  	curr_iovlen = m->msg_iovlen;
  	my_msg.msg_iov = &my_iov;
  	my_msg.msg_iovlen = 1;
  	my_msg.msg_flags = m->msg_flags;
  	my_msg.msg_name = NULL;
  	bytes_sent = 0;
  
  	hdr_size = msg_hdr_sz(&tport->phdr);
  
  	while (curr_iovlen--) {
  		curr_start = curr_iov->iov_base;
  		curr_left = curr_iov->iov_len;
  
  		while (curr_left) {
  			bytes_to_send = tport->max_pkt - hdr_size;
  			if (bytes_to_send > TIPC_MAX_USER_MSG_SIZE)
  				bytes_to_send = TIPC_MAX_USER_MSG_SIZE;
  			if (curr_left < bytes_to_send)
  				bytes_to_send = curr_left;
  			my_iov.iov_base = curr_start;
  			my_iov.iov_len = bytes_to_send;
  			if ((res = send_packet(NULL, sock, &my_msg, 0)) < 0) {
  				if (bytes_sent)
  					res = bytes_sent;
  				goto exit;
  			}
  			curr_left -= bytes_to_send;
  			curr_start += bytes_to_send;
  			bytes_sent += bytes_to_send;
  		}
  
  		curr_iov++;
  	}
  	res = bytes_sent;
  exit:
  	release_sock(sk);
  	return res;
  }
  
  /**
   * auto_connect - complete connection setup to a remote port
   * @sock: socket structure
   * @msg: peer's response message
   *
   * Returns 0 on success, errno otherwise
   */
  
  static int auto_connect(struct socket *sock, struct tipc_msg *msg)
  {
  	struct tipc_sock *tsock = tipc_sk(sock->sk);
  
  	if (msg_errcode(msg)) {
  		sock->state = SS_DISCONNECTING;
  		return -ECONNREFUSED;
  	}
  
  	tsock->peer_name.ref = msg_origport(msg);
  	tsock->peer_name.node = msg_orignode(msg);
  	tipc_connect2port(tsock->p->ref, &tsock->peer_name);
  	tipc_set_portimportance(tsock->p->ref, msg_importance(msg));
  	sock->state = SS_CONNECTED;
  	return 0;
  }
  
  /**
   * set_orig_addr - capture sender's address for received message
   * @m: descriptor for message info
   * @msg: received message header
   *
   * Note: Address is not captured if not requested by receiver.
   */
  
  static void set_orig_addr(struct msghdr *m, struct tipc_msg *msg)
  {
  	struct sockaddr_tipc *addr = (struct sockaddr_tipc *)m->msg_name;
  
  	if (addr) {
  		addr->family = AF_TIPC;
  		addr->addrtype = TIPC_ADDR_ID;
  		addr->addr.id.ref = msg_origport(msg);
  		addr->addr.id.node = msg_orignode(msg);
  		addr->addr.name.domain = 0;   	/* could leave uninitialized */
  		addr->scope = 0;   		/* could leave uninitialized */
  		m->msg_namelen = sizeof(struct sockaddr_tipc);
  	}
  }
  
  /**
   * anc_data_recv - optionally capture ancillary data for received message
   * @m: descriptor for message info
   * @msg: received message header
   * @tport: TIPC port associated with message
   *
   * Note: Ancillary data is not captured if not requested by receiver.
   *
   * Returns 0 if successful, otherwise errno
   */
  
  static int anc_data_recv(struct msghdr *m, struct tipc_msg *msg,
  				struct tipc_port *tport)
  {
  	u32 anc_data[3];
  	u32 err;
  	u32 dest_type;
  	int has_name;
  	int res;
  
  	if (likely(m->msg_controllen == 0))
  		return 0;
  
  	/* Optionally capture errored message object(s) */
  
  	err = msg ? msg_errcode(msg) : 0;
  	if (unlikely(err)) {
  		anc_data[0] = err;
  		anc_data[1] = msg_data_sz(msg);
  		if ((res = put_cmsg(m, SOL_TIPC, TIPC_ERRINFO, 8, anc_data)))
  			return res;
  		if (anc_data[1] &&
  		    (res = put_cmsg(m, SOL_TIPC, TIPC_RETDATA, anc_data[1],
  				    msg_data(msg))))
  			return res;
  	}
  
  	/* Optionally capture message destination object */
  
  	dest_type = msg ? msg_type(msg) : TIPC_DIRECT_MSG;
  	switch (dest_type) {
  	case TIPC_NAMED_MSG:
  		has_name = 1;
  		anc_data[0] = msg_nametype(msg);
  		anc_data[1] = msg_namelower(msg);
  		anc_data[2] = msg_namelower(msg);
  		break;
  	case TIPC_MCAST_MSG:
  		has_name = 1;
  		anc_data[0] = msg_nametype(msg);
  		anc_data[1] = msg_namelower(msg);
  		anc_data[2] = msg_nameupper(msg);
  		break;
  	case TIPC_CONN_MSG:
  		has_name = (tport->conn_type != 0);
  		anc_data[0] = tport->conn_type;
  		anc_data[1] = tport->conn_instance;
  		anc_data[2] = tport->conn_instance;
  		break;
  	default:
  		has_name = 0;
  	}
  	if (has_name &&
  	    (res = put_cmsg(m, SOL_TIPC, TIPC_DESTNAME, 12, anc_data)))
  		return res;
  
  	return 0;
  }
  
  /**
   * recv_msg - receive packet-oriented message
   * @iocb: (unused)
   * @m: descriptor for message info
   * @buf_len: total size of user buffer area
   * @flags: receive flags
   *
   * Used for SOCK_DGRAM, SOCK_RDM, and SOCK_SEQPACKET messages.
   * If the complete message doesn't fit in user area, truncate it.
   *
   * Returns size of returned message data, errno otherwise
   */
  
  static int recv_msg(struct kiocb *iocb, struct socket *sock,
  		    struct msghdr *m, size_t buf_len, int flags)
  {
  	struct sock *sk = sock->sk;
  	struct tipc_port *tport = tipc_sk_port(sk);
  	struct sk_buff *buf;
  	struct tipc_msg *msg;
  	unsigned int sz;
  	u32 err;
  	int res;
  
  	/* Catch invalid receive requests */
  
  	if (m->msg_iovlen != 1)
  		return -EOPNOTSUPP;   /* Don't do multiple iovec entries yet */
  
  	if (unlikely(!buf_len))
  		return -EINVAL;
  
  	lock_sock(sk);
  
  	if (unlikely(sock->state == SS_UNCONNECTED)) {
  		res = -ENOTCONN;
  		goto exit;
  	}
  
  restart:
  
  	/* Look for a message in receive queue; wait if necessary */
  
  	while (skb_queue_empty(&sk->sk_receive_queue)) {
  		if (sock->state == SS_DISCONNECTING) {
  			res = -ENOTCONN;
  			goto exit;
  		}
  		if (flags & MSG_DONTWAIT) {
  			res = -EWOULDBLOCK;
  			goto exit;
  		}
  		release_sock(sk);
  		res = wait_event_interruptible(*sk_sleep(sk),
  			(!skb_queue_empty(&sk->sk_receive_queue) ||
  			 (sock->state == SS_DISCONNECTING)));
  		lock_sock(sk);
  		if (res)
  			goto exit;
  	}
  
  	/* Look at first message in receive queue */
  
  	buf = skb_peek(&sk->sk_receive_queue);
  	msg = buf_msg(buf);
  	sz = msg_data_sz(msg);
  	err = msg_errcode(msg);
  
  	/* Complete connection setup for an implied connect */
  
  	if (unlikely(sock->state == SS_CONNECTING)) {
  		res = auto_connect(sock, msg);
  		if (res)
  			goto exit;
  	}
  
  	/* Discard an empty non-errored message & try again */
  
  	if ((!sz) && (!err)) {
  		advance_rx_queue(sk);
  		goto restart;
  	}
  
  	/* Capture sender's address (optional) */
  
  	set_orig_addr(m, msg);
  
  	/* Capture ancillary data (optional) */
  
  	res = anc_data_recv(m, msg, tport);
  	if (res)
  		goto exit;
  
  	/* Capture message data (if valid) & compute return value (always) */
  
  	if (!err) {
  		if (unlikely(buf_len < sz)) {
  			sz = buf_len;
  			m->msg_flags |= MSG_TRUNC;
  		}
  		if (unlikely(copy_to_user(m->msg_iov->iov_base, msg_data(msg),
  					  sz))) {
  			res = -EFAULT;
  			goto exit;
  		}
  		res = sz;
  	} else {
  		if ((sock->state == SS_READY) ||
  		    ((err == TIPC_CONN_SHUTDOWN) || m->msg_control))
  			res = 0;
  		else
  			res = -ECONNRESET;
  	}
  
  	/* Consume received message (optional) */
  
  	if (likely(!(flags & MSG_PEEK))) {
  		if ((sock->state != SS_READY) &&
  		    (++tport->conn_unacked >= TIPC_FLOW_CONTROL_WIN))
  			tipc_acknowledge(tport->ref, tport->conn_unacked);
  		advance_rx_queue(sk);
  	}
  exit:
  	release_sock(sk);
  	return res;
  }
  
  /**
   * recv_stream - receive stream-oriented data
   * @iocb: (unused)
   * @m: descriptor for message info
   * @buf_len: total size of user buffer area
   * @flags: receive flags
   *
   * Used for SOCK_STREAM messages only.  If not enough data is available
   * will optionally wait for more; never truncates data.
   *
   * Returns size of returned message data, errno otherwise
   */
  
  static int recv_stream(struct kiocb *iocb, struct socket *sock,
  		       struct msghdr *m, size_t buf_len, int flags)
  {
  	struct sock *sk = sock->sk;
  	struct tipc_port *tport = tipc_sk_port(sk);
  	struct sk_buff *buf;
  	struct tipc_msg *msg;
  	unsigned int sz;
  	int sz_to_copy;
  	int sz_copied = 0;
  	int needed;
  	char __user *crs = m->msg_iov->iov_base;
  	unsigned char *buf_crs;
  	u32 err;
  	int res = 0;
  
  	/* Catch invalid receive attempts */
  
  	if (m->msg_iovlen != 1)
  		return -EOPNOTSUPP;   /* Don't do multiple iovec entries yet */
  
  	if (unlikely(!buf_len))
  		return -EINVAL;
  
  	lock_sock(sk);
  
  	if (unlikely((sock->state == SS_UNCONNECTED) ||
  		     (sock->state == SS_CONNECTING))) {
  		res = -ENOTCONN;
  		goto exit;
  	}
  
  restart:
  
  	/* Look for a message in receive queue; wait if necessary */
  
  	while (skb_queue_empty(&sk->sk_receive_queue)) {
  		if (sock->state == SS_DISCONNECTING) {
  			res = -ENOTCONN;
  			goto exit;
  		}
  		if (flags & MSG_DONTWAIT) {
  			res = -EWOULDBLOCK;
  			goto exit;
  		}
  		release_sock(sk);
  		res = wait_event_interruptible(*sk_sleep(sk),
  			(!skb_queue_empty(&sk->sk_receive_queue) ||
  			 (sock->state == SS_DISCONNECTING)));
  		lock_sock(sk);
  		if (res)
  			goto exit;
  	}
  
  	/* Look at first message in receive queue */
  
  	buf = skb_peek(&sk->sk_receive_queue);
  	msg = buf_msg(buf);
  	sz = msg_data_sz(msg);
  	err = msg_errcode(msg);
  
  	/* Discard an empty non-errored message & try again */
  
  	if ((!sz) && (!err)) {
  		advance_rx_queue(sk);
  		goto restart;
  	}
  
  	/* Optionally capture sender's address & ancillary data of first msg */
  
  	if (sz_copied == 0) {
  		set_orig_addr(m, msg);
  		res = anc_data_recv(m, msg, tport);
  		if (res)
  			goto exit;
  	}
  
  	/* Capture message data (if valid) & compute return value (always) */
  
  	if (!err) {
  		buf_crs = (unsigned char *)(TIPC_SKB_CB(buf)->handle);
  		sz = (unsigned char *)msg + msg_size(msg) - buf_crs;
  
  		needed = (buf_len - sz_copied);
  		sz_to_copy = (sz <= needed) ? sz : needed;
  		if (unlikely(copy_to_user(crs, buf_crs, sz_to_copy))) {
  			res = -EFAULT;
  			goto exit;
  		}
  		sz_copied += sz_to_copy;
  
  		if (sz_to_copy < sz) {
  			if (!(flags & MSG_PEEK))
  				TIPC_SKB_CB(buf)->handle = buf_crs + sz_to_copy;
  			goto exit;
  		}
  
  		crs += sz_to_copy;
  	} else {
  		if (sz_copied != 0)
  			goto exit; /* can't add error msg to valid data */
  
  		if ((err == TIPC_CONN_SHUTDOWN) || m->msg_control)
  			res = 0;
  		else
  			res = -ECONNRESET;
  	}
  
  	/* Consume received message (optional) */
  
  	if (likely(!(flags & MSG_PEEK))) {
  		if (unlikely(++tport->conn_unacked >= TIPC_FLOW_CONTROL_WIN))
  			tipc_acknowledge(tport->ref, tport->conn_unacked);
  		advance_rx_queue(sk);
  	}
  
  	/* Loop around if more data is required */
  
  	if ((sz_copied < buf_len) &&	/* didn't get all requested data */
  	    (!skb_queue_empty(&sk->sk_receive_queue) ||
  	     (flags & MSG_WAITALL)) &&	/* and more is ready or required */
  	    (!(flags & MSG_PEEK)) &&	/* and aren't just peeking at data */
  	    (!err))			/* and haven't reached a FIN */
  		goto restart;
  
  exit:
  	release_sock(sk);
  	return sz_copied ? sz_copied : res;
  }
  
  /**
   * rx_queue_full - determine if receive queue can accept another message
   * @msg: message to be added to queue
   * @queue_size: current size of queue
   * @base: nominal maximum size of queue
   *
   * Returns 1 if queue is unable to accept message, 0 otherwise
   */
  
  static int rx_queue_full(struct tipc_msg *msg, u32 queue_size, u32 base)
  {
  	u32 threshold;
  	u32 imp = msg_importance(msg);
  
  	if (imp == TIPC_LOW_IMPORTANCE)
  		threshold = base;
  	else if (imp == TIPC_MEDIUM_IMPORTANCE)
  		threshold = base * 2;
  	else if (imp == TIPC_HIGH_IMPORTANCE)
  		threshold = base * 100;
  	else
  		return 0;
  
  	if (msg_connected(msg))
  		threshold *= 4;
  
  	return (queue_size >= threshold);
  }
  
  /**
   * filter_rcv - validate incoming message
   * @sk: socket
   * @buf: message
   *
   * Enqueues message on receive queue if acceptable; optionally handles
   * disconnect indication for a connected socket.
   *
   * Called with socket lock already taken; port lock may also be taken.
   *
   * Returns TIPC error status code (TIPC_OK if message is not to be rejected)
   */
  
  static u32 filter_rcv(struct sock *sk, struct sk_buff *buf)
  {
  	struct socket *sock = sk->sk_socket;
  	struct tipc_msg *msg = buf_msg(buf);
  	u32 recv_q_len;
  
  	/* Reject message if it is wrong sort of message for socket */
  
  	/*
  	 * WOULD IT BE BETTER TO JUST DISCARD THESE MESSAGES INSTEAD?
  	 * "NO PORT" ISN'T REALLY THE RIGHT ERROR CODE, AND THERE MAY
  	 * BE SECURITY IMPLICATIONS INHERENT IN REJECTING INVALID TRAFFIC
  	 */
  
  	if (sock->state == SS_READY) {
  		if (msg_connected(msg)) {
  			msg_dbg(msg, "dispatch filter 1\n");
  			return TIPC_ERR_NO_PORT;
  		}
  	} else {
  		if (msg_mcast(msg)) {
  			msg_dbg(msg, "dispatch filter 2\n");
  			return TIPC_ERR_NO_PORT;
  		}
  		if (sock->state == SS_CONNECTED) {
  			if (!msg_connected(msg)) {
  				msg_dbg(msg, "dispatch filter 3\n");
  				return TIPC_ERR_NO_PORT;
  			}
  		}
  		else if (sock->state == SS_CONNECTING) {
  			if (!msg_connected(msg) && (msg_errcode(msg) == 0)) {
  				msg_dbg(msg, "dispatch filter 4\n");
  				return TIPC_ERR_NO_PORT;
  			}
  		}
  		else if (sock->state == SS_LISTENING) {
  			if (msg_connected(msg) || msg_errcode(msg)) {
  				msg_dbg(msg, "dispatch filter 5\n");
  				return TIPC_ERR_NO_PORT;
  			}
  		}
  		else if (sock->state == SS_DISCONNECTING) {
  			msg_dbg(msg, "dispatch filter 6\n");
  			return TIPC_ERR_NO_PORT;
  		}
  		else /* (sock->state == SS_UNCONNECTED) */ {
  			if (msg_connected(msg) || msg_errcode(msg)) {
  				msg_dbg(msg, "dispatch filter 7\n");
  				return TIPC_ERR_NO_PORT;
  			}
  		}
  	}
  
  	/* Reject message if there isn't room to queue it */
  
  	recv_q_len = (u32)atomic_read(&tipc_queue_size);
  	if (unlikely(recv_q_len >= OVERLOAD_LIMIT_BASE)) {
  		if (rx_queue_full(msg, recv_q_len, OVERLOAD_LIMIT_BASE))
  			return TIPC_ERR_OVERLOAD;
  	}
  	recv_q_len = skb_queue_len(&sk->sk_receive_queue);
  	if (unlikely(recv_q_len >= (OVERLOAD_LIMIT_BASE / 2))) {
  		if (rx_queue_full(msg, recv_q_len, OVERLOAD_LIMIT_BASE / 2))
  			return TIPC_ERR_OVERLOAD;
  	}
  
  	/* Enqueue message (finally!) */
  
  	msg_dbg(msg, "<DISP<: ");
  	TIPC_SKB_CB(buf)->handle = msg_data(msg);
  	atomic_inc(&tipc_queue_size);
  	__skb_queue_tail(&sk->sk_receive_queue, buf);
  
  	/* Initiate connection termination for an incoming 'FIN' */
  
  	if (unlikely(msg_errcode(msg) && (sock->state == SS_CONNECTED))) {
  		sock->state = SS_DISCONNECTING;
  		tipc_disconnect_port(tipc_sk_port(sk));
  	}
  
  	if (waitqueue_active(sk_sleep(sk)))
  		wake_up_interruptible(sk_sleep(sk));
  	return TIPC_OK;
  }
  
  /**
   * backlog_rcv - handle incoming message from backlog queue
   * @sk: socket
   * @buf: message
   *
   * Caller must hold socket lock, but not port lock.
   *
   * Returns 0
   */
  
  static int backlog_rcv(struct sock *sk, struct sk_buff *buf)
  {
  	u32 res;
  
  	res = filter_rcv(sk, buf);
  	if (res)
  		tipc_reject_msg(buf, res);
  	return 0;
  }
  
  /**
   * dispatch - handle incoming message
   * @tport: TIPC port that received message
   * @buf: message
   *
   * Called with port lock already taken.
   *
   * Returns TIPC error status code (TIPC_OK if message is not to be rejected)
   */
  
  static u32 dispatch(struct tipc_port *tport, struct sk_buff *buf)
  {
  	struct sock *sk = (struct sock *)tport->usr_handle;
  	u32 res;
  
  	/*
  	 * Process message if socket is unlocked; otherwise add to backlog queue
  	 *
  	 * This code is based on sk_receive_skb(), but must be distinct from it
  	 * since a TIPC-specific filter/reject mechanism is utilized
  	 */
  
  	bh_lock_sock(sk);
  	if (!sock_owned_by_user(sk)) {
  		res = filter_rcv(sk, buf);
  	} else {
  		if (sk_add_backlog(sk, buf))
  			res = TIPC_ERR_OVERLOAD;
  		else
  			res = TIPC_OK;
  	}
  	bh_unlock_sock(sk);
  
  	return res;
  }
  
  /**
   * wakeupdispatch - wake up port after congestion
   * @tport: port to wakeup
   *
   * Called with port lock already taken.
   */
  
  static void wakeupdispatch(struct tipc_port *tport)
  {
  	struct sock *sk = (struct sock *)tport->usr_handle;
  
  	if (waitqueue_active(sk_sleep(sk)))
  		wake_up_interruptible(sk_sleep(sk));
  }
  
  /**
   * connect - establish a connection to another TIPC port
   * @sock: socket structure
   * @dest: socket address for destination port
   * @destlen: size of socket address data structure
   * @flags: file-related flags associated with socket
   *
   * Returns 0 on success, errno otherwise
   */
  
  static int connect(struct socket *sock, struct sockaddr *dest, int destlen,
  		   int flags)
  {
  	struct sock *sk = sock->sk;
  	struct sockaddr_tipc *dst = (struct sockaddr_tipc *)dest;
  	struct msghdr m = {NULL,};
  	struct sk_buff *buf;
  	struct tipc_msg *msg;
  	int res;
  
  	lock_sock(sk);
  
  	/* For now, TIPC does not allow use of connect() with DGRAM/RDM types */
  
  	if (sock->state == SS_READY) {
  		res = -EOPNOTSUPP;
  		goto exit;
  	}
  
  	/* For now, TIPC does not support the non-blocking form of connect() */
  
  	if (flags & O_NONBLOCK) {
  		res = -EWOULDBLOCK;
  		goto exit;
  	}
  
  	/* Issue Posix-compliant error code if socket is in the wrong state */
  
  	if (sock->state == SS_LISTENING) {
  		res = -EOPNOTSUPP;
  		goto exit;
  	}
  	if (sock->state == SS_CONNECTING) {
  		res = -EALREADY;
  		goto exit;
  	}
  	if (sock->state != SS_UNCONNECTED) {
  		res = -EISCONN;
  		goto exit;
  	}
  
  	/*
  	 * Reject connection attempt using multicast address
  	 *
  	 * Note: send_msg() validates the rest of the address fields,
  	 *       so there's no need to do it here
  	 */
  
  	if (dst->addrtype == TIPC_ADDR_MCAST) {
  		res = -EINVAL;
  		goto exit;
  	}
  
  	/* Reject any messages already in receive queue (very unlikely) */
  
  	reject_rx_queue(sk);
  
  	/* Send a 'SYN-' to destination */
  
  	m.msg_name = dest;
  	m.msg_namelen = destlen;
  	res = send_msg(NULL, sock, &m, 0);
  	if (res < 0) {
  		goto exit;
  	}
  
  	/* Wait until an 'ACK' or 'RST' arrives, or a timeout occurs */
  
  	release_sock(sk);
  	res = wait_event_interruptible_timeout(*sk_sleep(sk),
  			(!skb_queue_empty(&sk->sk_receive_queue) ||
  			(sock->state != SS_CONNECTING)),
  			sk->sk_rcvtimeo);
  	lock_sock(sk);
  
  	if (res > 0) {
  		buf = skb_peek(&sk->sk_receive_queue);
  		if (buf != NULL) {
  			msg = buf_msg(buf);
  			res = auto_connect(sock, msg);
  			if (!res) {
  				if (!msg_data_sz(msg))
  					advance_rx_queue(sk);
  			}
  		} else {
  			if (sock->state == SS_CONNECTED) {
  				res = -EISCONN;
  			} else {
  				res = -ECONNREFUSED;
  			}
  		}
  	} else {
  		if (res == 0)
  			res = -ETIMEDOUT;
  		else
  			; /* leave "res" unchanged */
  		sock->state = SS_DISCONNECTING;
  	}
  
  exit:
  	release_sock(sk);
  	return res;
  }
  
  /**
   * listen - allow socket to listen for incoming connections
   * @sock: socket structure
   * @len: (unused)
   *
   * Returns 0 on success, errno otherwise
   */
  
  static int listen(struct socket *sock, int len)
  {
  	struct sock *sk = sock->sk;
  	int res;
  
  	lock_sock(sk);
  
  	if (sock->state == SS_READY)
  		res = -EOPNOTSUPP;
  	else if (sock->state != SS_UNCONNECTED)
  		res = -EINVAL;
  	else {
  		sock->state = SS_LISTENING;
  		res = 0;
  	}
  
  	release_sock(sk);
  	return res;
  }
  
  /**
   * accept - wait for connection request
   * @sock: listening socket
   * @newsock: new socket that is to be connected
   * @flags: file-related flags associated with socket
   *
   * Returns 0 on success, errno otherwise
   */
  
  static int accept(struct socket *sock, struct socket *new_sock, int flags)
  {
  	struct sock *sk = sock->sk;
  	struct sk_buff *buf;
  	int res;
  
  	lock_sock(sk);
  
  	if (sock->state == SS_READY) {
  		res = -EOPNOTSUPP;
  		goto exit;
  	}
  	if (sock->state != SS_LISTENING) {
  		res = -EINVAL;
  		goto exit;
  	}
  
  	while (skb_queue_empty(&sk->sk_receive_queue)) {
  		if (flags & O_NONBLOCK) {
  			res = -EWOULDBLOCK;
  			goto exit;
  		}
  		release_sock(sk);
  		res = wait_event_interruptible(*sk_sleep(sk),
  				(!skb_queue_empty(&sk->sk_receive_queue)));
  		lock_sock(sk);
  		if (res)
  			goto exit;
  	}
  
  	buf = skb_peek(&sk->sk_receive_queue);
  
  	res = tipc_create(sock_net(sock->sk), new_sock, 0, 0);
  	if (!res) {
  		struct sock *new_sk = new_sock->sk;
  		struct tipc_sock *new_tsock = tipc_sk(new_sk);
  		struct tipc_port *new_tport = new_tsock->p;
  		u32 new_ref = new_tport->ref;
  		struct tipc_msg *msg = buf_msg(buf);
  
  		lock_sock(new_sk);
  
  		/*
  		 * Reject any stray messages received by new socket
  		 * before the socket lock was taken (very, very unlikely)
  		 */
  
  		reject_rx_queue(new_sk);
  
  		/* Connect new socket to it's peer */
  
  		new_tsock->peer_name.ref = msg_origport(msg);
  		new_tsock->peer_name.node = msg_orignode(msg);
  		tipc_connect2port(new_ref, &new_tsock->peer_name);
  		new_sock->state = SS_CONNECTED;
  
  		tipc_set_portimportance(new_ref, msg_importance(msg));
  		if (msg_named(msg)) {
  			new_tport->conn_type = msg_nametype(msg);
  			new_tport->conn_instance = msg_nameinst(msg);
  		}
  
  		/*
  		 * Respond to 'SYN-' by discarding it & returning 'ACK'-.
  		 * Respond to 'SYN+' by queuing it on new socket.
  		 */
  
  		msg_dbg(msg,"<ACC<: ");
  		if (!msg_data_sz(msg)) {
  			struct msghdr m = {NULL,};
  
  			advance_rx_queue(sk);
  			send_packet(NULL, new_sock, &m, 0);
  		} else {
  			__skb_dequeue(&sk->sk_receive_queue);
  			__skb_queue_head(&new_sk->sk_receive_queue, buf);
  		}
  		release_sock(new_sk);
  	}
  exit:
  	release_sock(sk);
  	return res;
  }
  
  /**
   * shutdown - shutdown socket connection
   * @sock: socket structure
   * @how: direction to close (must be SHUT_RDWR)
   *
   * Terminates connection (if necessary), then purges socket's receive queue.
   *
   * Returns 0 on success, errno otherwise
   */
  
  static int shutdown(struct socket *sock, int how)
  {
  	struct sock *sk = sock->sk;
  	struct tipc_port *tport = tipc_sk_port(sk);
  	struct sk_buff *buf;
  	int res;
  
  	if (how != SHUT_RDWR)
  		return -EINVAL;
  
  	lock_sock(sk);
  
  	switch (sock->state) {
  	case SS_CONNECTING:
  	case SS_CONNECTED:
  
  		/* Disconnect and send a 'FIN+' or 'FIN-' message to peer */
  restart:
  		buf = __skb_dequeue(&sk->sk_receive_queue);
  		if (buf) {
  			atomic_dec(&tipc_queue_size);
  			if (TIPC_SKB_CB(buf)->handle != msg_data(buf_msg(buf))) {
  				buf_discard(buf);
  				goto restart;
  			}
  			tipc_disconnect(tport->ref);
  			tipc_reject_msg(buf, TIPC_CONN_SHUTDOWN);
  		} else {
  			tipc_shutdown(tport->ref);
  		}
  
  		sock->state = SS_DISCONNECTING;
  
  		/* fall through */
  
  	case SS_DISCONNECTING:
  
  		/* Discard any unreceived messages; wake up sleeping tasks */
  
  		discard_rx_queue(sk);
  		if (waitqueue_active(sk_sleep(sk)))
  			wake_up_interruptible(sk_sleep(sk));
  		res = 0;
  		break;
  
  	default:
  		res = -ENOTCONN;
  	}
  
  	release_sock(sk);
  	return res;
  }
  
  /**
   * setsockopt - set socket option
   * @sock: socket structure
   * @lvl: option level
   * @opt: option identifier
   * @ov: pointer to new option value
   * @ol: length of option value
   *
   * For stream sockets only, accepts and ignores all IPPROTO_TCP options
   * (to ease compatibility).
   *
   * Returns 0 on success, errno otherwise
   */
  
  static int setsockopt(struct socket *sock,
  		      int lvl, int opt, char __user *ov, unsigned int ol)
  {
  	struct sock *sk = sock->sk;
  	struct tipc_port *tport = tipc_sk_port(sk);
  	u32 value;
  	int res;
  
  	if ((lvl == IPPROTO_TCP) && (sock->type == SOCK_STREAM))
  		return 0;
  	if (lvl != SOL_TIPC)
  		return -ENOPROTOOPT;
  	if (ol < sizeof(value))
  		return -EINVAL;
  	if ((res = get_user(value, (u32 __user *)ov)))
  		return res;
  
  	lock_sock(sk);
  
  	switch (opt) {
  	case TIPC_IMPORTANCE:
  		res = tipc_set_portimportance(tport->ref, value);
  		break;
  	case TIPC_SRC_DROPPABLE:
  		if (sock->type != SOCK_STREAM)
  			res = tipc_set_portunreliable(tport->ref, value);
  		else
  			res = -ENOPROTOOPT;
  		break;
  	case TIPC_DEST_DROPPABLE:
  		res = tipc_set_portunreturnable(tport->ref, value);
  		break;
  	case TIPC_CONN_TIMEOUT:
  		sk->sk_rcvtimeo = msecs_to_jiffies(value);
  		/* no need to set "res", since already 0 at this point */
  		break;
  	default:
  		res = -EINVAL;
  	}
  
  	release_sock(sk);
  
  	return res;
  }
  
  /**
   * getsockopt - get socket option
   * @sock: socket structure
   * @lvl: option level
   * @opt: option identifier
   * @ov: receptacle for option value
   * @ol: receptacle for length of option value
   *
   * For stream sockets only, returns 0 length result for all IPPROTO_TCP options
   * (to ease compatibility).
   *
   * Returns 0 on success, errno otherwise
   */
  
  static int getsockopt(struct socket *sock,
  		      int lvl, int opt, char __user *ov, int __user *ol)
  {
  	struct sock *sk = sock->sk;
  	struct tipc_port *tport = tipc_sk_port(sk);
  	int len;
  	u32 value;
  	int res;
  
  	if ((lvl == IPPROTO_TCP) && (sock->type == SOCK_STREAM))
  		return put_user(0, ol);
  	if (lvl != SOL_TIPC)
  		return -ENOPROTOOPT;
  	if ((res = get_user(len, ol)))
  		return res;
  
  	lock_sock(sk);
  
  	switch (opt) {
  	case TIPC_IMPORTANCE:
  		res = tipc_portimportance(tport->ref, &value);
  		break;
  	case TIPC_SRC_DROPPABLE:
  		res = tipc_portunreliable(tport->ref, &value);
  		break;
  	case TIPC_DEST_DROPPABLE:
  		res = tipc_portunreturnable(tport->ref, &value);
  		break;
  	case TIPC_CONN_TIMEOUT:
  		value = jiffies_to_msecs(sk->sk_rcvtimeo);
  		/* no need to set "res", since already 0 at this point */
  		break;
  	 case TIPC_NODE_RECVQ_DEPTH:
  		value = (u32)atomic_read(&tipc_queue_size);
  		break;
  	 case TIPC_SOCK_RECVQ_DEPTH:
  		value = skb_queue_len(&sk->sk_receive_queue);
  		break;
  	default:
  		res = -EINVAL;
  	}
  
  	release_sock(sk);
  
  	if (res) {
  		/* "get" failed */
  	}
  	else if (len < sizeof(value)) {
  		res = -EINVAL;
  	}
  	else if (copy_to_user(ov, &value, sizeof(value))) {
  		res = -EFAULT;
  	}
  	else {
  		res = put_user(sizeof(value), ol);
  	}
  
  	return res;
  }
  
  /**
   * Protocol switches for the various types of TIPC sockets
   */
  
  static const struct proto_ops msg_ops = {
  	.owner 		= THIS_MODULE,
  	.family		= AF_TIPC,
  	.release	= release,
  	.bind		= bind,
  	.connect	= connect,
  	.socketpair	= sock_no_socketpair,
  	.accept		= accept,
  	.getname	= get_name,
  	.poll		= poll,
  	.ioctl		= sock_no_ioctl,
  	.listen		= listen,
  	.shutdown	= shutdown,
  	.setsockopt	= setsockopt,
  	.getsockopt	= getsockopt,
  	.sendmsg	= send_msg,
  	.recvmsg	= recv_msg,
  	.mmap		= sock_no_mmap,
  	.sendpage	= sock_no_sendpage
  };
  
  static const struct proto_ops packet_ops = {
  	.owner 		= THIS_MODULE,
  	.family		= AF_TIPC,
  	.release	= release,
  	.bind		= bind,
  	.connect	= connect,
  	.socketpair	= sock_no_socketpair,
  	.accept		= accept,
  	.getname	= get_name,
  	.poll		= poll,
  	.ioctl		= sock_no_ioctl,
  	.listen		= listen,
  	.shutdown	= shutdown,
  	.setsockopt	= setsockopt,
  	.getsockopt	= getsockopt,
  	.sendmsg	= send_packet,
  	.recvmsg	= recv_msg,
  	.mmap		= sock_no_mmap,
  	.sendpage	= sock_no_sendpage
  };
  
  static const struct proto_ops stream_ops = {
  	.owner 		= THIS_MODULE,
  	.family		= AF_TIPC,
  	.release	= release,
  	.bind		= bind,
  	.connect	= connect,
  	.socketpair	= sock_no_socketpair,
  	.accept		= accept,
  	.getname	= get_name,
  	.poll		= poll,
  	.ioctl		= sock_no_ioctl,
  	.listen		= listen,
  	.shutdown	= shutdown,
  	.setsockopt	= setsockopt,
  	.getsockopt	= getsockopt,
  	.sendmsg	= send_stream,
  	.recvmsg	= recv_stream,
  	.mmap		= sock_no_mmap,
  	.sendpage	= sock_no_sendpage
  };
  
  static const struct net_proto_family tipc_family_ops = {
  	.owner 		= THIS_MODULE,
  	.family		= AF_TIPC,
  	.create		= tipc_create
  };
  
  static struct proto tipc_proto = {
  	.name		= "TIPC",
  	.owner		= THIS_MODULE,
  	.obj_size	= sizeof(struct tipc_sock)
  };
  
  /**
   * tipc_socket_init - initialize TIPC socket interface
   *
   * Returns 0 on success, errno otherwise
   */
  int tipc_socket_init(void)
  {
  	int res;
  
  	res = proto_register(&tipc_proto, 1);
  	if (res) {
  		err("Failed to register TIPC protocol type\n");
  		goto out;
  	}
  
  	res = sock_register(&tipc_family_ops);
  	if (res) {
  		err("Failed to register TIPC socket type\n");
  		proto_unregister(&tipc_proto);
  		goto out;
  	}
  
  	sockets_enabled = 1;
   out:
  	return res;
  }
  
  /**
   * tipc_socket_stop - stop TIPC socket interface
   */
  
  void tipc_socket_stop(void)
  {
  	if (!sockets_enabled)
  		return;
  
  	sockets_enabled = 0;
  	sock_unregister(tipc_family_ops.family);
  	proto_unregister(&tipc_proto);
  }
  
  