/*
   * af_llc.c - LLC User Interface SAPs
   * Description:
   *   Functions in this module are implementation of socket based llc
   *   communications for the Linux operating system. Support of llc class
   *   one and class two is provided via SOCK_DGRAM and SOCK_STREAM
   *   respectively.
   *
   *   An llc2 connection is (mac + sap), only one llc2 sap connection
   *   is allowed per mac. Though one sap may have multiple mac + sap
   *   connections.
   *
   * Copyright (c) 2001 by Jay Schulist <jschlst@samba.org>
   *		 2002-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   *
   * This program can be redistributed or modified under the terms of the
   * GNU General Public License as published by the Free Software Foundation.
   * This program is distributed without any warranty or implied warranty
   * of merchantability or fitness for a particular purpose.
   *
   * See the GNU General Public License for more details.
   */

  #include <linux/compiler.h>

  #include <linux/kernel.h>
  #include <linux/module.h>

  #include <linux/rtnetlink.h>
  #include <linux/init.h>

  #include <linux/slab.h>

  #include <net/llc.h>
  #include <net/llc_sap.h>
  #include <net/llc_pdu.h>
  #include <net/llc_conn.h>

  #include <net/tcp_states.h>

  
  /* remember: uninitialized global data is zeroed because its in .bss */
  static u16 llc_ui_sap_last_autoport = LLC_SAP_DYN_START;
  static u16 llc_ui_sap_link_no_max[256];
  static struct sockaddr_llc llc_ui_addrnull;

  static const struct proto_ops llc_ui_ops;

  static int llc_ui_wait_for_conn(struct sock *sk, long timeout);
  static int llc_ui_wait_for_disc(struct sock *sk, long timeout);

  static int llc_ui_wait_for_busy_core(struct sock *sk, long timeout);

  
  #if 0
  #define dprintk(args...) printk(KERN_DEBUG args)
  #else
  #define dprintk(args...)
  #endif

  /* Maybe we'll add some more in the future. */
  #define LLC_CMSG_PKTINFO	1

  /**
   *	llc_ui_next_link_no - return the next unused link number for a sap
   *	@sap: Address of sap to get link number from.
   *
   *	Return the next unused link number for a given sap.
   */

  static inline u16 llc_ui_next_link_no(int sap)

  {
  	return llc_ui_sap_link_no_max[sap]++;
  }
  
  /**
   *	llc_proto_type - return eth protocol for ARP header type
   *	@arphrd: ARP header type.
   *
   *	Given an ARP header type return the corresponding ethernet protocol.
   */

  static inline __be16 llc_proto_type(u16 arphrd)

  {

  	return htons(ETH_P_802_2);

  }
  
  /**
   *	llc_ui_addr_null - determines if a address structure is null
   *	@addr: Address to test if null.
   */

  static inline u8 llc_ui_addr_null(struct sockaddr_llc *addr)

  {
  	return !memcmp(addr, &llc_ui_addrnull, sizeof(*addr));
  }
  
  /**
   *	llc_ui_header_len - return length of llc header based on operation
   *	@sk: Socket which contains a valid llc socket type.
   *	@addr: Complete sockaddr_llc structure received from the user.
   *
   *	Provide the length of the llc header depending on what kind of
   *	operation the user would like to perform and the type of socket.
   *	Returns the correct llc header length.
   */

  static inline u8 llc_ui_header_len(struct sock *sk, struct sockaddr_llc *addr)

  {
  	u8 rc = LLC_PDU_LEN_U;
  
  	if (addr->sllc_test || addr->sllc_xid)
  		rc = LLC_PDU_LEN_U;
  	else if (sk->sk_type == SOCK_STREAM)
  		rc = LLC_PDU_LEN_I;
  	return rc;
  }
  
  /**
   *	llc_ui_send_data - send data via reliable llc2 connection
   *	@sk: Connection the socket is using.
   *	@skb: Data the user wishes to send.

   *	@noblock: can we block waiting for data?
   *
   *	Send data via reliable llc2 connection.
   *	Returns 0 upon success, non-zero if action did not succeed.
   */
  static int llc_ui_send_data(struct sock* sk, struct sk_buff *skb, int noblock)
  {
  	struct llc_sock* llc = llc_sk(sk);
  	int rc = 0;

  	if (unlikely(llc_data_accept_state(llc->state) ||

  		     llc->remote_busy_flag ||
  		     llc->p_flag)) {

  		long timeout = sock_sndtimeo(sk, noblock);

  
  		rc = llc_ui_wait_for_busy_core(sk, timeout);
  	}

  	if (unlikely(!rc))

  		rc = llc_build_and_send_pkt(sk, skb);
  	return rc;
  }
  
  static void llc_ui_sk_init(struct socket *sock, struct sock *sk)
  {

  	sock_graft(sk, sock);

  	sk->sk_type	= sock->type;

  	sock->ops	= &llc_ui_ops;
  }
  
  static struct proto llc_proto = {

  	.name	  = "LLC",

  	.owner	  = THIS_MODULE,
  	.obj_size = sizeof(struct llc_sock),

  	.slab_flags = SLAB_DESTROY_BY_RCU,

  };
  
  /**
   *	llc_ui_create - alloc and init a new llc_ui socket

   *	@net: network namespace (must be default network)

   *	@sock: Socket to initialize and attach allocated sk to.
   *	@protocol: Unused.

   *	@kern: on behalf of kernel or userspace

   *
   *	Allocate and initialize a new llc_ui socket, validate the user wants a
   *	socket type we have available.
   *	Returns 0 upon success, negative upon failure.
   */

  static int llc_ui_create(struct net *net, struct socket *sock, int protocol,
  			 int kern)

  {
  	struct sock *sk;
  	int rc = -ESOCKTNOSUPPORT;

  	if (!ns_capable(net->user_ns, CAP_NET_RAW))

  		return -EPERM;

  	if (!net_eq(net, &init_net))

  		return -EAFNOSUPPORT;

  	if (likely(sock->type == SOCK_DGRAM || sock->type == SOCK_STREAM)) {

  		rc = -ENOMEM;

  		sk = llc_sk_alloc(net, PF_LLC, GFP_KERNEL, &llc_proto);

  		if (sk) {
  			rc = 0;
  			llc_ui_sk_init(sock, sk);
  		}
  	}
  	return rc;
  }
  
  /**
   *	llc_ui_release - shutdown socket
   *	@sock: Socket to release.
   *
   *	Shutdown and deallocate an existing socket.
   */
  static int llc_ui_release(struct socket *sock)
  {
  	struct sock *sk = sock->sk;
  	struct llc_sock *llc;

  	if (unlikely(sk == NULL))

  		goto out;
  	sock_hold(sk);
  	lock_sock(sk);
  	llc = llc_sk(sk);

  	dprintk("%s: closing local(%02X) remote(%02X)
  ", __func__,

  		llc->laddr.lsap, llc->daddr.lsap);
  	if (!llc_send_disc(sk))
  		llc_ui_wait_for_disc(sk, sk->sk_rcvtimeo);

  	if (!sock_flag(sk, SOCK_ZAPPED))

  		llc_sap_remove_socket(llc->sap, sk);
  	release_sock(sk);

  	if (llc->dev)
  		dev_put(llc->dev);
  	sock_put(sk);
  	llc_sk_free(sk);
  out:
  	return 0;
  }
  
  /**
   *	llc_ui_autoport - provide dynamically allocate SAP number
   *
   *	Provide the caller with a dynamically allocated SAP number according
   *	to the rules that are set in this function. Returns: 0, upon failure,
   *	SAP number otherwise.
   */
  static int llc_ui_autoport(void)
  {
  	struct llc_sap *sap;
  	int i, tries = 0;
  
  	while (tries < LLC_SAP_DYN_TRIES) {
  		for (i = llc_ui_sap_last_autoport;
  		     i < LLC_SAP_DYN_STOP; i += 2) {
  			sap = llc_sap_find(i);
  			if (!sap) {
  				llc_ui_sap_last_autoport = i + 2;
  				goto out;
  			}

  			llc_sap_put(sap);

  		}
  		llc_ui_sap_last_autoport = LLC_SAP_DYN_START;
  		tries++;
  	}
  	i = 0;
  out:
  	return i;
  }
  
  /**

   *	llc_ui_autobind - automatically bind a socket to a sap
   *	@sock: socket to bind
   *	@addr: address to connect to
   *
   * 	Used by llc_ui_connect and llc_ui_sendmsg when the user hasn't
   * 	specifically used llc_ui_bind to bind to an specific address/sap

   *

   *	Returns: 0 upon success, negative otherwise.
   */
  static int llc_ui_autobind(struct socket *sock, struct sockaddr_llc *addr)
  {
  	struct sock *sk = sock->sk;
  	struct llc_sock *llc = llc_sk(sk);
  	struct llc_sap *sap;
  	int rc = -EINVAL;
  
  	if (!sock_flag(sk, SOCK_ZAPPED))
  		goto out;
  	rc = -ENODEV;

  	if (sk->sk_bound_dev_if) {
  		llc->dev = dev_get_by_index(&init_net, sk->sk_bound_dev_if);
  		if (llc->dev && addr->sllc_arphrd != llc->dev->type) {
  			dev_put(llc->dev);
  			llc->dev = NULL;
  		}
  	} else
  		llc->dev = dev_getfirstbyhwtype(&init_net, addr->sllc_arphrd);

  	if (!llc->dev)
  		goto out;
  	rc = -EUSERS;
  	llc->laddr.lsap = llc_ui_autoport();
  	if (!llc->laddr.lsap)
  		goto out;
  	rc = -EBUSY; /* some other network layer is using the sap */
  	sap = llc_sap_open(llc->laddr.lsap, NULL);
  	if (!sap)
  		goto out;
  	memcpy(llc->laddr.mac, llc->dev->dev_addr, IFHWADDRLEN);
  	memcpy(&llc->addr, addr, sizeof(llc->addr));
  	/* assign new connection to its SAP */
  	llc_sap_add_socket(sap, sk);
  	sock_reset_flag(sk, SOCK_ZAPPED);
  	rc = 0;
  out:
  	return rc;
  }
  
  /**
   *	llc_ui_bind - bind a socket to a specific address.
   *	@sock: Socket to bind an address to.
   *	@uaddr: Address the user wants the socket bound to.
   *	@addrlen: Length of the uaddr structure.
   *
   *	Bind a socket to a specific address. For llc a user is able to bind to

   *	a specific sap only or mac + sap.

   *	If the user desires to bind to a specific mac + sap, it is possible to
   *	have multiple sap connections via multiple macs.
   *	Bind and autobind for that matter must enforce the correct sap usage
   *	otherwise all hell will break loose.
   *	Returns: 0 upon success, negative otherwise.
   */
  static int llc_ui_bind(struct socket *sock, struct sockaddr *uaddr, int addrlen)
  {
  	struct sockaddr_llc *addr = (struct sockaddr_llc *)uaddr;
  	struct sock *sk = sock->sk;
  	struct llc_sock *llc = llc_sk(sk);
  	struct llc_sap *sap;
  	int rc = -EINVAL;

  	dprintk("%s: binding %02X
  ", __func__, addr->sllc_sap);

  	if (unlikely(!sock_flag(sk, SOCK_ZAPPED) || addrlen != sizeof(*addr)))

  		goto out;
  	rc = -EAFNOSUPPORT;

  	if (unlikely(addr->sllc_family != AF_LLC))

  		goto out;

  	rc = -ENODEV;

  	rcu_read_lock();

  	if (sk->sk_bound_dev_if) {

  		llc->dev = dev_get_by_index_rcu(&init_net, sk->sk_bound_dev_if);

  		if (llc->dev) {
  			if (!addr->sllc_arphrd)
  				addr->sllc_arphrd = llc->dev->type;

  			if (is_zero_ether_addr(addr->sllc_mac))

  				memcpy(addr->sllc_mac, llc->dev->dev_addr,
  				       IFHWADDRLEN);
  			if (addr->sllc_arphrd != llc->dev->type ||

  			    !ether_addr_equal(addr->sllc_mac,
  					      llc->dev->dev_addr)) {

  				rc = -EINVAL;

  				llc->dev = NULL;
  			}
  		}
  	} else

  		llc->dev = dev_getbyhwaddr_rcu(&init_net, addr->sllc_arphrd,

  					   addr->sllc_mac);

  	if (llc->dev)
  		dev_hold(llc->dev);
  	rcu_read_unlock();

  	if (!llc->dev)
  		goto out;

  	if (!addr->sllc_sap) {
  		rc = -EUSERS;
  		addr->sllc_sap = llc_ui_autoport();
  		if (!addr->sllc_sap)
  			goto out;
  	}
  	sap = llc_sap_find(addr->sllc_sap);
  	if (!sap) {
  		sap = llc_sap_open(addr->sllc_sap, NULL);
  		rc = -EBUSY; /* some other network layer is using the sap */
  		if (!sap)
  			goto out;
  	} else {
  		struct llc_addr laddr, daddr;
  		struct sock *ask;
  
  		memset(&laddr, 0, sizeof(laddr));
  		memset(&daddr, 0, sizeof(daddr));
  		/*

  		 * FIXME: check if the address is multicast,

  		 * 	  only SOCK_DGRAM can do this.
  		 */
  		memcpy(laddr.mac, addr->sllc_mac, IFHWADDRLEN);
  		laddr.lsap = addr->sllc_sap;
  		rc = -EADDRINUSE; /* mac + sap clash. */
  		ask = llc_lookup_established(sap, &daddr, &laddr);
  		if (ask) {
  			sock_put(ask);

  			goto out_put;

  		}
  	}
  	llc->laddr.lsap = addr->sllc_sap;
  	memcpy(llc->laddr.mac, addr->sllc_mac, IFHWADDRLEN);
  	memcpy(&llc->addr, addr, sizeof(llc->addr));
  	/* assign new connection to its SAP */
  	llc_sap_add_socket(sap, sk);
  	sock_reset_flag(sk, SOCK_ZAPPED);
  	rc = 0;

  out_put:
  	llc_sap_put(sap);

  out:
  	return rc;
  }
  
  /**
   *	llc_ui_shutdown - shutdown a connect llc2 socket.
   *	@sock: Socket to shutdown.
   *	@how: What part of the socket to shutdown.
   *
   *	Shutdown a connected llc2 socket. Currently this function only supports
   *	shutting down both sends and receives (2), we could probably make this
   *	function such that a user can shutdown only half the connection but not
   *	right now.
   *	Returns: 0 upon success, negative otherwise.
   */
  static int llc_ui_shutdown(struct socket *sock, int how)
  {
  	struct sock *sk = sock->sk;
  	int rc = -ENOTCONN;
  
  	lock_sock(sk);

  	if (unlikely(sk->sk_state != TCP_ESTABLISHED))

  		goto out;
  	rc = -EINVAL;
  	if (how != 2)
  		goto out;
  	rc = llc_send_disc(sk);
  	if (!rc)
  		rc = llc_ui_wait_for_disc(sk, sk->sk_rcvtimeo);
  	/* Wake up anyone sleeping in poll */
  	sk->sk_state_change(sk);
  out:
  	release_sock(sk);
  	return rc;
  }
  
  /**
   *	llc_ui_connect - Connect to a remote llc2 mac + sap.
   *	@sock: Socket which will be connected to the remote destination.
   *	@uaddr: Remote and possibly the local address of the new connection.
   *	@addrlen: Size of uaddr structure.
   *	@flags: Operational flags specified by the user.
   *
   *	Connect to a remote llc2 mac + sap. The caller must specify the
   *	destination mac and address to connect to. If the user hasn't previously
   *	called bind(2) with a smac the address of the first interface of the
   *	specified arp type will be used.
   *	This function will autobind if user did not previously call bind.
   *	Returns: 0 upon success, negative otherwise.
   */
  static int llc_ui_connect(struct socket *sock, struct sockaddr *uaddr,
  			  int addrlen, int flags)
  {
  	struct sock *sk = sock->sk;
  	struct llc_sock *llc = llc_sk(sk);
  	struct sockaddr_llc *addr = (struct sockaddr_llc *)uaddr;

  	int rc = -EINVAL;
  
  	lock_sock(sk);

  	if (unlikely(addrlen != sizeof(*addr)))

  		goto out;
  	rc = -EAFNOSUPPORT;

  	if (unlikely(addr->sllc_family != AF_LLC))
  		goto out;
  	if (unlikely(sk->sk_type != SOCK_STREAM))
  		goto out;
  	rc = -EALREADY;
  	if (unlikely(sock->state == SS_CONNECTING))

  		goto out;
  	/* bind connection to sap if user hasn't done it. */
  	if (sock_flag(sk, SOCK_ZAPPED)) {
  		/* bind to sap with null dev, exclusive */
  		rc = llc_ui_autobind(sock, addr);
  		if (rc)
  			goto out;

  	}

  	llc->daddr.lsap = addr->sllc_sap;
  	memcpy(llc->daddr.mac, addr->sllc_mac, IFHWADDRLEN);

  	sock->state = SS_CONNECTING;
  	sk->sk_state   = TCP_SYN_SENT;
  	llc->link   = llc_ui_next_link_no(llc->sap->laddr.lsap);

  	rc = llc_establish_connection(sk, llc->dev->dev_addr,

  				      addr->sllc_mac, addr->sllc_sap);
  	if (rc) {

  		dprintk("%s: llc_ui_send_conn failed :-(
  ", __func__);

  		sock->state  = SS_UNCONNECTED;
  		sk->sk_state = TCP_CLOSE;
  		goto out;
  	}

  
  	if (sk->sk_state == TCP_SYN_SENT) {

  		const long timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);

  
  		if (!timeo || !llc_ui_wait_for_conn(sk, timeo))
  			goto out;
  
  		rc = sock_intr_errno(timeo);
  		if (signal_pending(current))
  			goto out;
  	}
  
  	if (sk->sk_state == TCP_CLOSE)
  		goto sock_error;
  
  	sock->state = SS_CONNECTED;
  	rc = 0;

  out:
  	release_sock(sk);
  	return rc;

  sock_error:
  	rc = sock_error(sk) ? : -ECONNABORTED;
  	sock->state = SS_UNCONNECTED;
  	goto out;

  }
  
  /**
   *	llc_ui_listen - allow a normal socket to accept incoming connections
   *	@sock: Socket to allow incoming connections on.
   *	@backlog: Number of connections to queue.
   *
   *	Allow a normal socket to accept incoming connections.
   *	Returns 0 upon success, negative otherwise.
   */
  static int llc_ui_listen(struct socket *sock, int backlog)
  {
  	struct sock *sk = sock->sk;
  	int rc = -EINVAL;
  
  	lock_sock(sk);

  	if (unlikely(sock->state != SS_UNCONNECTED))

  		goto out;
  	rc = -EOPNOTSUPP;

  	if (unlikely(sk->sk_type != SOCK_STREAM))

  		goto out;
  	rc = -EAGAIN;
  	if (sock_flag(sk, SOCK_ZAPPED))
  		goto out;
  	rc = 0;

  	if (!(unsigned int)backlog)	/* BSDism */

  		backlog = 1;
  	sk->sk_max_ack_backlog = backlog;
  	if (sk->sk_state != TCP_LISTEN) {
  		sk->sk_ack_backlog = 0;
  		sk->sk_state	   = TCP_LISTEN;
  	}
  	sk->sk_socket->flags |= __SO_ACCEPTCON;
  out:
  	release_sock(sk);
  	return rc;
  }

  static int llc_ui_wait_for_disc(struct sock *sk, long timeout)

  {

  	DEFINE_WAIT(wait);
  	int rc = 0;

  	while (1) {

  		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);

  		if (sk_wait_event(sk, &timeout, sk->sk_state == TCP_CLOSE))
  			break;

  		rc = -ERESTARTSYS;
  		if (signal_pending(current))
  			break;
  		rc = -EAGAIN;
  		if (!timeout)
  			break;

  		rc = 0;

  	}

  	finish_wait(sk_sleep(sk), &wait);

  	return rc;
  }

  static int llc_ui_wait_for_conn(struct sock *sk, long timeout)

  {

  	DEFINE_WAIT(wait);

  	while (1) {

  		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);

  		if (sk_wait_event(sk, &timeout, sk->sk_state != TCP_SYN_SENT))
  			break;

  		if (signal_pending(current) || !timeout)

  			break;
  	}

  	finish_wait(sk_sleep(sk), &wait);

  	return timeout;

  }

  static int llc_ui_wait_for_busy_core(struct sock *sk, long timeout)

  {

  	DEFINE_WAIT(wait);

  	struct llc_sock *llc = llc_sk(sk);
  	int rc;

  	while (1) {

  		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);

  		rc = 0;

  		if (sk_wait_event(sk, &timeout,
  				  (sk->sk_shutdown & RCV_SHUTDOWN) ||

  				  (!llc_data_accept_state(llc->state) &&

  				   !llc->remote_busy_flag &&

  				   !llc->p_flag)))

  			break;

  		rc = -ERESTARTSYS;
  		if (signal_pending(current))
  			break;
  		rc = -EAGAIN;
  		if (!timeout)
  			break;
  	}

  	finish_wait(sk_sleep(sk), &wait);

  	return rc;
  }

  static int llc_wait_data(struct sock *sk, long timeo)

  {

  	int rc;

  	while (1) {

  		/*
  		 * POSIX 1003.1g mandates this order.
  		 */

  		rc = sock_error(sk);
  		if (rc)

  			break;

  		rc = 0;

  		if (sk->sk_shutdown & RCV_SHUTDOWN)

  			break;

  		rc = -EAGAIN;
  		if (!timeo)
  			break;
  		rc = sock_intr_errno(timeo);

  		if (signal_pending(current))
  			break;

  		rc = 0;
  		if (sk_wait_data(sk, &timeo))

  			break;
  	}

  	return rc;
  }

  static void llc_cmsg_rcv(struct msghdr *msg, struct sk_buff *skb)
  {
  	struct llc_sock *llc = llc_sk(skb->sk);
  
  	if (llc->cmsg_flags & LLC_CMSG_PKTINFO) {
  		struct llc_pktinfo info;
  
  		info.lpi_ifindex = llc_sk(skb->sk)->dev->ifindex;
  		llc_pdu_decode_dsap(skb, &info.lpi_sap);
  		llc_pdu_decode_da(skb, info.lpi_mac);
  		put_cmsg(msg, SOL_LLC, LLC_OPT_PKTINFO, sizeof(info), &info);
  	}
  }

  /**
   *	llc_ui_accept - accept a new incoming connection.
   *	@sock: Socket which connections arrive on.
   *	@newsock: Socket to move incoming connection to.
   *	@flags: User specified operational flags.
   *
   *	Accept a new incoming connection.
   *	Returns 0 upon success, negative otherwise.
   */
  static int llc_ui_accept(struct socket *sock, struct socket *newsock, int flags)
  {
  	struct sock *sk = sock->sk, *newsk;
  	struct llc_sock *llc, *newllc;
  	struct sk_buff *skb;
  	int rc = -EOPNOTSUPP;

  	dprintk("%s: accepting on %02X
  ", __func__,

  		llc_sk(sk)->laddr.lsap);

  	lock_sock(sk);

  	if (unlikely(sk->sk_type != SOCK_STREAM))

  		goto out;
  	rc = -EINVAL;

  	if (unlikely(sock->state != SS_UNCONNECTED ||
  		     sk->sk_state != TCP_LISTEN))

  		goto out;
  	/* wait for a connection to arrive. */

  	if (skb_queue_empty(&sk->sk_receive_queue)) {

  		rc = llc_wait_data(sk, sk->sk_rcvtimeo);

  		if (rc)
  			goto out;
  	}

  	dprintk("%s: got a new connection on %02X
  ", __func__,

  		llc_sk(sk)->laddr.lsap);

  	skb = skb_dequeue(&sk->sk_receive_queue);
  	rc = -EINVAL;
  	if (!skb->sk)
  		goto frees;
  	rc = 0;
  	newsk = skb->sk;
  	/* attach connection to a new socket. */
  	llc_ui_sk_init(newsock, newsk);
  	sock_reset_flag(newsk, SOCK_ZAPPED);
  	newsk->sk_state		= TCP_ESTABLISHED;
  	newsock->state		= SS_CONNECTED;
  	llc			= llc_sk(sk);
  	newllc			= llc_sk(newsk);
  	memcpy(&newllc->addr, &llc->addr, sizeof(newllc->addr));
  	newllc->link = llc_ui_next_link_no(newllc->laddr.lsap);
  
  	/* put original socket back into a clean listen state. */
  	sk->sk_state = TCP_LISTEN;
  	sk->sk_ack_backlog--;

  	dprintk("%s: ok success on %02X, client on %02X
  ", __func__,

  		llc_sk(sk)->addr.sllc_sap, newllc->daddr.lsap);
  frees:
  	kfree_skb(skb);
  out:
  	release_sock(sk);
  	return rc;
  }
  
  /**
   *	llc_ui_recvmsg - copy received data to the socket user.
   *	@sock: Socket to copy data from.
   *	@msg: Various user space related information.

   *	@len: Size of user buffer.

   *	@flags: User specified flags.
   *
   *	Copy received data to the socket user.
   *	Returns non-negative upon success, negative otherwise.
   */
  static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock,

  			  struct msghdr *msg, size_t len, int flags)

  {

  	DECLARE_SOCKADDR(struct sockaddr_llc *, uaddr, msg->msg_name);

  	const int nonblock = flags & MSG_DONTWAIT;
  	struct sk_buff *skb = NULL;
  	struct sock *sk = sock->sk;
  	struct llc_sock *llc = llc_sk(sk);

  	unsigned long cpu_flags;

  	size_t copied = 0;

  	u32 peek_seq = 0;

  	u32 *seq, skb_len;

  	unsigned long used;
  	int target;	/* Read at least this many bytes */
  	long timeo;

  	lock_sock(sk);

  	copied = -ENOTCONN;

  	if (unlikely(sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_LISTEN))

  		goto out;

  
  	timeo = sock_rcvtimeo(sk, nonblock);
  
  	seq = &llc->copied_seq;
  	if (flags & MSG_PEEK) {
  		peek_seq = llc->copied_seq;
  		seq = &peek_seq;

  	}

  
  	target = sock_rcvlowat(sk, flags & MSG_WAITALL, len);
  	copied = 0;
  
  	do {
  		u32 offset;
  
  		/*
  		 * We need to check signals first, to get correct SIGURG
  		 * handling. FIXME: Need to check this doesn't impact 1003.1g
  		 * and move it down to the bottom of the loop
  		 */
  		if (signal_pending(current)) {
  			if (copied)
  				break;
  			copied = timeo ? sock_intr_errno(timeo) : -EAGAIN;
  			break;
  		}
  
  		/* Next get a buffer. */
  
  		skb = skb_peek(&sk->sk_receive_queue);
  		if (skb) {
  			offset = *seq;
  			goto found_ok_skb;
  		}
  		/* Well, if we have backlog, try to process it now yet. */
  
  		if (copied >= target && !sk->sk_backlog.tail)
  			break;
  
  		if (copied) {
  			if (sk->sk_err ||
  			    sk->sk_state == TCP_CLOSE ||
  			    (sk->sk_shutdown & RCV_SHUTDOWN) ||
  			    !timeo ||
  			    (flags & MSG_PEEK))
  				break;
  		} else {
  			if (sock_flag(sk, SOCK_DONE))
  				break;
  
  			if (sk->sk_err) {
  				copied = sock_error(sk);
  				break;
  			}
  			if (sk->sk_shutdown & RCV_SHUTDOWN)
  				break;

  			if (sk->sk_type == SOCK_STREAM && sk->sk_state == TCP_CLOSE) {

  				if (!sock_flag(sk, SOCK_DONE)) {
  					/*
  					 * This occurs when user tries to read
  					 * from never connected socket.
  					 */
  					copied = -ENOTCONN;
  					break;
  				}
  				break;
  			}
  			if (!timeo) {
  				copied = -EAGAIN;
  				break;
  			}
  		}
  
  		if (copied >= target) { /* Do not sleep, just process backlog. */
  			release_sock(sk);
  			lock_sock(sk);
  		} else
  			sk_wait_data(sk, &timeo);
  
  		if ((flags & MSG_PEEK) && peek_seq != llc->copied_seq) {

  			net_dbg_ratelimited("LLC(%s:%d): Application bug, race in MSG_PEEK
  ",
  					    current->comm,
  					    task_pid_nr(current));

  			peek_seq = llc->copied_seq;
  		}
  		continue;
  	found_ok_skb:

  		skb_len = skb->len;

  		/* Ok so how much can we use? */
  		used = skb->len - offset;
  		if (len < used)
  			used = len;
  
  		if (!(flags & MSG_TRUNC)) {
  			int rc = skb_copy_datagram_iovec(skb, offset,
  							 msg->msg_iov, used);
  			if (rc) {
  				/* Exception. Bailout! */
  				if (!copied)
  					copied = -EFAULT;
  				break;
  			}
  		}
  
  		*seq += used;
  		copied += used;
  		len -= used;

  		/* For non stream protcols we get one packet per recvmsg call */
  		if (sk->sk_type != SOCK_STREAM)
  			goto copy_uaddr;

  		if (!(flags & MSG_PEEK)) {

  			spin_lock_irqsave(&sk->sk_receive_queue.lock, cpu_flags);

  			sk_eat_skb(sk, skb, false);

  			spin_unlock_irqrestore(&sk->sk_receive_queue.lock, cpu_flags);

  			*seq = 0;
  		}

  		/* Partial read */

  		if (used + offset < skb_len)

  			continue;

  	} while (len > 0);

  out:
  	release_sock(sk);

  	return copied;
  copy_uaddr:
  	if (uaddr != NULL && skb != NULL) {
  		memcpy(uaddr, llc_ui_skb_cb(skb), sizeof(*uaddr));
  		msg->msg_namelen = sizeof(*uaddr);
  	}

  	if (llc_sk(sk)->cmsg_flags)
  		llc_cmsg_rcv(msg, skb);

  
  	if (!(flags & MSG_PEEK)) {

  			spin_lock_irqsave(&sk->sk_receive_queue.lock, cpu_flags);

  			sk_eat_skb(sk, skb, false);

  			spin_unlock_irqrestore(&sk->sk_receive_queue.lock, cpu_flags);

  			*seq = 0;
  	}

  	goto out;

  }
  
  /**
   *	llc_ui_sendmsg - Transmit data provided by the socket user.
   *	@sock: Socket to transmit data from.
   *	@msg: Various user related information.
   *	@len: Length of data to transmit.
   *
   *	Transmit data provided by the socket user.
   *	Returns non-negative upon success, negative otherwise.
   */
  static int llc_ui_sendmsg(struct kiocb *iocb, struct socket *sock,
  			  struct msghdr *msg, size_t len)
  {
  	struct sock *sk = sock->sk;
  	struct llc_sock *llc = llc_sk(sk);

  	DECLARE_SOCKADDR(struct sockaddr_llc *, addr, msg->msg_name);

  	int flags = msg->msg_flags;
  	int noblock = flags & MSG_DONTWAIT;

  	struct sk_buff *skb;
  	size_t size = 0;
  	int rc = -EINVAL, copied = 0, hdrlen;

  	dprintk("%s: sending from %02X to %02X
  ", __func__,

  		llc->laddr.lsap, llc->daddr.lsap);
  	lock_sock(sk);
  	if (addr) {
  		if (msg->msg_namelen < sizeof(*addr))
  			goto release;
  	} else {
  		if (llc_ui_addr_null(&llc->addr))
  			goto release;
  		addr = &llc->addr;
  	}
  	/* must bind connection to sap if user hasn't done it. */
  	if (sock_flag(sk, SOCK_ZAPPED)) {
  		/* bind to sap with null dev, exclusive. */
  		rc = llc_ui_autobind(sock, addr);
  		if (rc)
  			goto release;
  	}

  	hdrlen = llc->dev->hard_header_len + llc_ui_header_len(sk, addr);

  	size = hdrlen + len;

  	if (size > llc->dev->mtu)
  		size = llc->dev->mtu;

  	copied = size - hdrlen;
  	release_sock(sk);
  	skb = sock_alloc_send_skb(sk, size, noblock, &rc);
  	lock_sock(sk);
  	if (!skb)
  		goto release;

  	skb->dev      = llc->dev;

  	skb->protocol = llc_proto_type(addr->sllc_arphrd);

  	skb_reserve(skb, hdrlen);

  	rc = memcpy_fromiovec(skb_put(skb, copied), msg->msg_iov, copied);
  	if (rc)
  		goto out;
  	if (sk->sk_type == SOCK_DGRAM || addr->sllc_ua) {
  		llc_build_and_send_ui_pkt(llc->sap, skb, addr->sllc_mac,
  					  addr->sllc_sap);
  		goto out;
  	}
  	if (addr->sllc_test) {
  		llc_build_and_send_test_pkt(llc->sap, skb, addr->sllc_mac,
  					    addr->sllc_sap);
  		goto out;
  	}
  	if (addr->sllc_xid) {
  		llc_build_and_send_xid_pkt(llc->sap, skb, addr->sllc_mac,
  					   addr->sllc_sap);
  		goto out;
  	}
  	rc = -ENOPROTOOPT;
  	if (!(sk->sk_type == SOCK_STREAM && !addr->sllc_ua))
  		goto out;
  	rc = llc_ui_send_data(sk, skb, noblock);

  out:

  	if (rc) {

  		kfree_skb(skb);
  release:

  		dprintk("%s: failed sending from %02X to %02X: %d
  ",

  			__func__, llc->laddr.lsap, llc->daddr.lsap, rc);

  	}

  	release_sock(sk);
  	return rc ? : copied;
  }
  
  /**
   *	llc_ui_getname - return the address info of a socket
   *	@sock: Socket to get address of.
   *	@uaddr: Address structure to return information.
   *	@uaddrlen: Length of address structure.
   *	@peer: Does user want local or remote address information.
   *
   *	Return the address information of a socket.
   */
  static int llc_ui_getname(struct socket *sock, struct sockaddr *uaddr,
  			  int *uaddrlen, int peer)
  {
  	struct sockaddr_llc sllc;
  	struct sock *sk = sock->sk;
  	struct llc_sock *llc = llc_sk(sk);

  	int rc = -EBADF;

  	memset(&sllc, 0, sizeof(sllc));

  	lock_sock(sk);
  	if (sock_flag(sk, SOCK_ZAPPED))
  		goto out;
  	*uaddrlen = sizeof(sllc);

  	if (peer) {
  		rc = -ENOTCONN;
  		if (sk->sk_state != TCP_ESTABLISHED)
  			goto out;
  		if(llc->dev)
  			sllc.sllc_arphrd = llc->dev->type;
  		sllc.sllc_sap = llc->daddr.lsap;
  		memcpy(&sllc.sllc_mac, &llc->daddr.mac, IFHWADDRLEN);
  	} else {
  		rc = -EINVAL;
  		if (!llc->sap)
  			goto out;
  		sllc.sllc_sap = llc->sap->laddr.lsap;
  
  		if (llc->dev) {
  			sllc.sllc_arphrd = llc->dev->type;

  			memcpy(&sllc.sllc_mac, llc->dev->dev_addr,

  			       IFHWADDRLEN);
  		}
  	}
  	rc = 0;
  	sllc.sllc_family = AF_LLC;
  	memcpy(uaddr, &sllc, sizeof(sllc));
  out:
  	release_sock(sk);
  	return rc;
  }
  
  /**
   *	llc_ui_ioctl - io controls for PF_LLC
   *	@sock: Socket to get/set info
   *	@cmd: command
   *	@arg: optional argument for cmd
   *
   *	get/set info on llc sockets
   */
  static int llc_ui_ioctl(struct socket *sock, unsigned int cmd,
  			unsigned long arg)
  {

  	return -ENOIOCTLCMD;

  }
  
  /**
   *	llc_ui_setsockopt - set various connection specific parameters.
   *	@sock: Socket to set options on.
   *	@level: Socket level user is requesting operations on.
   *	@optname: Operation name.

   *	@optval: User provided operation data.

   *	@optlen: Length of optval.
   *
   *	Set various connection specific parameters.
   */
  static int llc_ui_setsockopt(struct socket *sock, int level, int optname,

  			     char __user *optval, unsigned int optlen)

  {
  	struct sock *sk = sock->sk;
  	struct llc_sock *llc = llc_sk(sk);

  	unsigned int opt;
  	int rc = -EINVAL;

  
  	lock_sock(sk);

  	if (unlikely(level != SOL_LLC || optlen != sizeof(int)))

  		goto out;
  	rc = get_user(opt, (int __user *)optval);
  	if (rc)
  		goto out;
  	rc = -EINVAL;
  	switch (optname) {
  	case LLC_OPT_RETRY:
  		if (opt > LLC_OPT_MAX_RETRY)
  			goto out;
  		llc->n2 = opt;
  		break;
  	case LLC_OPT_SIZE:
  		if (opt > LLC_OPT_MAX_SIZE)
  			goto out;
  		llc->n1 = opt;
  		break;
  	case LLC_OPT_ACK_TMR_EXP:
  		if (opt > LLC_OPT_MAX_ACK_TMR_EXP)
  			goto out;

  		llc->ack_timer.expire = opt * HZ;

  		break;
  	case LLC_OPT_P_TMR_EXP:
  		if (opt > LLC_OPT_MAX_P_TMR_EXP)
  			goto out;

  		llc->pf_cycle_timer.expire = opt * HZ;

  		break;
  	case LLC_OPT_REJ_TMR_EXP:
  		if (opt > LLC_OPT_MAX_REJ_TMR_EXP)
  			goto out;

  		llc->rej_sent_timer.expire = opt * HZ;

  		break;
  	case LLC_OPT_BUSY_TMR_EXP:
  		if (opt > LLC_OPT_MAX_BUSY_TMR_EXP)
  			goto out;

  		llc->busy_state_timer.expire = opt * HZ;

  		break;
  	case LLC_OPT_TX_WIN:
  		if (opt > LLC_OPT_MAX_WIN)
  			goto out;
  		llc->k = opt;
  		break;
  	case LLC_OPT_RX_WIN:
  		if (opt > LLC_OPT_MAX_WIN)
  			goto out;
  		llc->rw = opt;
  		break;

  	case LLC_OPT_PKTINFO:
  		if (opt)
  			llc->cmsg_flags |= LLC_CMSG_PKTINFO;
  		else
  			llc->cmsg_flags &= ~LLC_CMSG_PKTINFO;
  		break;

  	default:
  		rc = -ENOPROTOOPT;
  		goto out;
  	}
  	rc = 0;
  out:
  	release_sock(sk);
  	return rc;
  }
  
  /**
   *	llc_ui_getsockopt - get connection specific socket info
   *	@sock: Socket to get information from.
   *	@level: Socket level user is requesting operations on.
   *	@optname: Operation name.
   *	@optval: Variable to return operation data in.
   *	@optlen: Length of optval.
   *
   *	Get connection specific socket information.
   */
  static int llc_ui_getsockopt(struct socket *sock, int level, int optname,
  			     char __user *optval, int __user *optlen)
  {
  	struct sock *sk = sock->sk;
  	struct llc_sock *llc = llc_sk(sk);
  	int val = 0, len = 0, rc = -EINVAL;
  
  	lock_sock(sk);

  	if (unlikely(level != SOL_LLC))

  		goto out;
  	rc = get_user(len, optlen);
  	if (rc)
  		goto out;
  	rc = -EINVAL;
  	if (len != sizeof(int))
  		goto out;
  	switch (optname) {
  	case LLC_OPT_RETRY:

  		val = llc->n2;					break;

  	case LLC_OPT_SIZE:

  		val = llc->n1;					break;

  	case LLC_OPT_ACK_TMR_EXP:

  		val = llc->ack_timer.expire / HZ;		break;

  	case LLC_OPT_P_TMR_EXP:

  		val = llc->pf_cycle_timer.expire / HZ;		break;

  	case LLC_OPT_REJ_TMR_EXP:

  		val = llc->rej_sent_timer.expire / HZ;		break;

  	case LLC_OPT_BUSY_TMR_EXP:

  		val = llc->busy_state_timer.expire / HZ;	break;

  	case LLC_OPT_TX_WIN:
  		val = llc->k;				break;
  	case LLC_OPT_RX_WIN:
  		val = llc->rw;				break;

  	case LLC_OPT_PKTINFO:
  		val = (llc->cmsg_flags & LLC_CMSG_PKTINFO) != 0;
  		break;

  	default:
  		rc = -ENOPROTOOPT;
  		goto out;
  	}
  	rc = 0;
  	if (put_user(len, optlen) || copy_to_user(optval, &val, len))
  		rc = -EFAULT;
  out:
  	release_sock(sk);
  	return rc;
  }

  static const struct net_proto_family llc_ui_family_ops = {

  	.family = PF_LLC,
  	.create = llc_ui_create,
  	.owner	= THIS_MODULE,
  };

  static const struct proto_ops llc_ui_ops = {

  	.family	     = PF_LLC,
  	.owner       = THIS_MODULE,
  	.release     = llc_ui_release,
  	.bind	     = llc_ui_bind,
  	.connect     = llc_ui_connect,
  	.socketpair  = sock_no_socketpair,
  	.accept      = llc_ui_accept,
  	.getname     = llc_ui_getname,
  	.poll	     = datagram_poll,
  	.ioctl       = llc_ui_ioctl,
  	.listen      = llc_ui_listen,
  	.shutdown    = llc_ui_shutdown,
  	.setsockopt  = llc_ui_setsockopt,
  	.getsockopt  = llc_ui_getsockopt,
  	.sendmsg     = llc_ui_sendmsg,
  	.recvmsg     = llc_ui_recvmsg,
  	.mmap	     = sock_no_mmap,
  	.sendpage    = sock_no_sendpage,
  };

  static const char llc_proc_err_msg[] __initconst =

  	KERN_CRIT "LLC: Unable to register the proc_fs entries
  ";

  static const char llc_sysctl_err_msg[] __initconst =

  	KERN_CRIT "LLC: Unable to register the sysctl entries
  ";

  static const char llc_sock_err_msg[] __initconst =

  	KERN_CRIT "LLC: Unable to register the network family
  ";

  static int __init llc2_init(void)
  {
  	int rc = proto_register(&llc_proto, 0);
  
  	if (rc != 0)
  		goto out;
  
  	llc_build_offset_table();
  	llc_station_init();
  	llc_ui_sap_last_autoport = LLC_SAP_DYN_START;
  	rc = llc_proc_init();

  	if (rc != 0) {
  		printk(llc_proc_err_msg);

  		goto out_station;

  	}
  	rc = llc_sysctl_init();
  	if (rc) {
  		printk(llc_sysctl_err_msg);
  		goto out_proc;
  	}
  	rc = sock_register(&llc_ui_family_ops);
  	if (rc) {
  		printk(llc_sock_err_msg);
  		goto out_sysctl;
  	}

  	llc_add_pack(LLC_DEST_SAP, llc_sap_handler);
  	llc_add_pack(LLC_DEST_CONN, llc_conn_handler);
  out:
  	return rc;

  out_sysctl:
  	llc_sysctl_exit();
  out_proc:
  	llc_proc_exit();

  out_station:
  	llc_station_exit();

  	proto_unregister(&llc_proto);
  	goto out;
  }
  
  static void __exit llc2_exit(void)
  {
  	llc_station_exit();
  	llc_remove_pack(LLC_DEST_SAP);
  	llc_remove_pack(LLC_DEST_CONN);
  	sock_unregister(PF_LLC);
  	llc_proc_exit();

  	llc_sysctl_exit();

  	proto_unregister(&llc_proto);
  }
  
  module_init(llc2_init);
  module_exit(llc2_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Procom 1997, Jay Schullist 2001, Arnaldo C. Melo 2001-2003");
  MODULE_DESCRIPTION("IEEE 802.2 PF_LLC support");
  MODULE_ALIAS_NETPROTO(PF_LLC);