/*
   * INET		An implementation of the TCP/IP protocol suite for the LINUX
   *		operating system.  INET is implemented using the  BSD Socket
   *		interface as the means of communication with the user level.
   *
   *		PF_INET protocol family socket handler.
   *

   * Authors:	Ross Biro

   *		Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
   *		Florian La Roche, <flla@stud.uni-sb.de>
   *		Alan Cox, <A.Cox@swansea.ac.uk>
   *
   * Changes (see also sock.c)
   *
   *		piggy,
   *		Karl Knutson	:	Socket protocol table
   *		A.N.Kuznetsov	:	Socket death error in accept().
   *		John Richardson :	Fix non blocking error in connect()
   *					so sockets that fail to connect
   *					don't return -EINPROGRESS.
   *		Alan Cox	:	Asynchronous I/O support
   *		Alan Cox	:	Keep correct socket pointer on sock
   *					structures
   *					when accept() ed
   *		Alan Cox	:	Semantics of SO_LINGER aren't state
   *					moved to close when you look carefully.
   *					With this fixed and the accept bug fixed
   *					some RPC stuff seems happier.
   *		Niibe Yutaka	:	4.4BSD style write async I/O
   *		Alan Cox,
   *		Tony Gale 	:	Fixed reuse semantics.
   *		Alan Cox	:	bind() shouldn't abort existing but dead
   *					sockets. Stops FTP netin:.. I hope.
   *		Alan Cox	:	bind() works correctly for RAW sockets.
   *					Note that FreeBSD at least was broken
   *					in this respect so be careful with
   *					compatibility tests...
   *		Alan Cox	:	routing cache support
   *		Alan Cox	:	memzero the socket structure for
   *					compactness.
   *		Matt Day	:	nonblock connect error handler
   *		Alan Cox	:	Allow large numbers of pending sockets
   *					(eg for big web sites), but only if
   *					specifically application requested.
   *		Alan Cox	:	New buffering throughout IP. Used
   *					dumbly.
   *		Alan Cox	:	New buffering now used smartly.
   *		Alan Cox	:	BSD rather than common sense
   *					interpretation of listen.
   *		Germano Caronni	:	Assorted small races.
   *		Alan Cox	:	sendmsg/recvmsg basic support.
   *		Alan Cox	:	Only sendmsg/recvmsg now supported.
   *		Alan Cox	:	Locked down bind (see security list).
   *		Alan Cox	:	Loosened bind a little.
   *		Mike McLagan	:	ADD/DEL DLCI Ioctls
   *	Willy Konynenberg	:	Transparent proxying support.
   *		David S. Miller	:	New socket lookup architecture.
   *					Some other random speedups.
   *		Cyrus Durgin	:	Cleaned up file for kmod hacks.
   *		Andi Kleen	:	Fix inet_stream_connect TCP race.
   *
   *		This program 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 of the License, or (at your option) any later version.
   */

  #define pr_fmt(fmt) "IPv4: " fmt

  #include <linux/err.h>

  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/socket.h>
  #include <linux/in.h>
  #include <linux/kernel.h>

  #include <linux/kmod.h>

  #include <linux/sched.h>
  #include <linux/timer.h>
  #include <linux/string.h>
  #include <linux/sockios.h>
  #include <linux/net.h>

  #include <linux/capability.h>

  #include <linux/fcntl.h>
  #include <linux/mm.h>
  #include <linux/interrupt.h>
  #include <linux/stat.h>
  #include <linux/init.h>
  #include <linux/poll.h>
  #include <linux/netfilter_ipv4.h>

  #include <linux/random.h>

  #include <linux/slab.h>

  #include <linux/uaccess.h>

  #include <linux/inet.h>
  #include <linux/igmp.h>

  #include <linux/inetdevice.h>

  #include <linux/netdevice.h>

  #include <net/checksum.h>

  #include <net/ip.h>
  #include <net/protocol.h>
  #include <net/arp.h>
  #include <net/route.h>
  #include <net/ip_fib.h>

  #include <net/inet_connection_sock.h>

  #include <net/tcp.h>
  #include <net/udp.h>

  #include <net/udplite.h>

  #include <net/ping.h>

  #include <linux/skbuff.h>
  #include <net/sock.h>
  #include <net/raw.h>
  #include <net/icmp.h>

  #include <net/inet_common.h>

  #include <net/ip_tunnels.h>

  #include <net/xfrm.h>

  #include <net/net_namespace.h>

  #include <net/secure_seq.h>

  #ifdef CONFIG_IP_MROUTE
  #include <linux/mroute.h>
  #endif

  #include <net/l3mdev.h>

  
  /* The inetsw table contains everything that inet_create needs to
   * build a new socket.
   */
  static struct list_head inetsw[SOCK_MAX];
  static DEFINE_SPINLOCK(inetsw_lock);
  
  /* New destruction routine */
  
  void inet_sock_destruct(struct sock *sk)
  {
  	struct inet_sock *inet = inet_sk(sk);
  
  	__skb_queue_purge(&sk->sk_receive_queue);
  	__skb_queue_purge(&sk->sk_error_queue);

  	sk_mem_reclaim(sk);

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

  		pr_err("Attempt to release TCP socket in state %d %p
  ",

  		       sk->sk_state, sk);
  		return;
  	}
  	if (!sock_flag(sk, SOCK_DEAD)) {

  		pr_err("Attempt to release alive inet socket %p
  ", sk);

  		return;
  	}

  	WARN_ON(atomic_read(&sk->sk_rmem_alloc));

  	WARN_ON(refcount_read(&sk->sk_wmem_alloc));

  	WARN_ON(sk->sk_wmem_queued);
  	WARN_ON(sk->sk_forward_alloc);

  	kfree(rcu_dereference_protected(inet->inet_opt, 1));

  	dst_release(rcu_dereference_check(sk->sk_dst_cache, 1));

  	dst_release(sk->sk_rx_dst);

  	sk_refcnt_debug_dec(sk);

  }

  EXPORT_SYMBOL(inet_sock_destruct);

  
  /*
   *	The routines beyond this point handle the behaviour of an AF_INET
   *	socket object. Mostly it punts to the subprotocols of IP to do
   *	the work.
   */
  
  /*
   *	Automatically bind an unbound socket.
   */
  
  static int inet_autobind(struct sock *sk)
  {
  	struct inet_sock *inet;
  	/* We may need to bind the socket. */
  	lock_sock(sk);
  	inet = inet_sk(sk);

  	if (!inet->inet_num) {

  		if (sk->sk_prot->get_port(sk, 0)) {
  			release_sock(sk);
  			return -EAGAIN;
  		}

  		inet->inet_sport = htons(inet->inet_num);

  	}
  	release_sock(sk);
  	return 0;
  }
  
  /*
   *	Move a socket into listening state.
   */
  int inet_listen(struct socket *sock, int backlog)
  {
  	struct sock *sk = sock->sk;
  	unsigned char old_state;
  	int err;
  
  	lock_sock(sk);
  
  	err = -EINVAL;
  	if (sock->state != SS_UNCONNECTED || sock->type != SOCK_STREAM)
  		goto out;
  
  	old_state = sk->sk_state;
  	if (!((1 << old_state) & (TCPF_CLOSE | TCPF_LISTEN)))
  		goto out;
  
  	/* Really, if the socket is already in listen state
  	 * we can only allow the backlog to be adjusted.
  	 */
  	if (old_state != TCP_LISTEN) {

  		/* Enable TFO w/o requiring TCP_FASTOPEN socket option.

  		 * Note that only TCP sockets (SOCK_STREAM) will reach here.

  		 * Also fastopen backlog may already been set via the option
  		 * because the socket was in TCP_LISTEN state previously but
  		 * was shutdown() rather than close().

  		 */

  		if ((sysctl_tcp_fastopen & TFO_SERVER_WO_SOCKOPT1) &&
  		    (sysctl_tcp_fastopen & TFO_SERVER_ENABLE) &&

  		    !inet_csk(sk)->icsk_accept_queue.fastopenq.max_qlen) {

  			fastopen_queue_tune(sk, backlog);

  			tcp_fastopen_init_key_once(true);

  		}

  		err = inet_csk_listen_start(sk, backlog);

  		if (err)
  			goto out;
  	}
  	sk->sk_max_ack_backlog = backlog;
  	err = 0;
  
  out:
  	release_sock(sk);
  	return err;
  }

  EXPORT_SYMBOL(inet_listen);

  
  /*
   *	Create an inet socket.
   */

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

  {
  	struct sock *sk;

  	struct inet_protosw *answer;
  	struct inet_sock *inet;
  	struct proto *answer_prot;
  	unsigned char answer_flags;

  	int try_loading_module = 0;

  	int err;

  	if (protocol < 0 || protocol >= IPPROTO_MAX)
  		return -EINVAL;

  	sock->state = SS_UNCONNECTED;
  
  	/* Look for the requested type/protocol pair. */

  lookup_protocol:

  	err = -ESOCKTNOSUPPORT;

  	rcu_read_lock();

  	list_for_each_entry_rcu(answer, &inetsw[sock->type], list) {

  		err = 0;

  		/* Check the non-wild match. */
  		if (protocol == answer->protocol) {
  			if (protocol != IPPROTO_IP)
  				break;
  		} else {
  			/* Check for the two wild cases. */
  			if (IPPROTO_IP == protocol) {
  				protocol = answer->protocol;
  				break;
  			}
  			if (IPPROTO_IP == answer->protocol)
  				break;
  		}

  		err = -EPROTONOSUPPORT;

  	}

  	if (unlikely(err)) {

  		if (try_loading_module < 2) {
  			rcu_read_unlock();
  			/*
  			 * Be more specific, e.g. net-pf-2-proto-132-type-1
  			 * (net-pf-PF_INET-proto-IPPROTO_SCTP-type-SOCK_STREAM)
  			 */
  			if (++try_loading_module == 1)
  				request_module("net-pf-%d-proto-%d-type-%d",
  					       PF_INET, protocol, sock->type);
  			/*
  			 * Fall back to generic, e.g. net-pf-2-proto-132
  			 * (net-pf-PF_INET-proto-IPPROTO_SCTP)
  			 */
  			else
  				request_module("net-pf-%d-proto-%d",
  					       PF_INET, protocol);
  			goto lookup_protocol;
  		} else
  			goto out_rcu_unlock;
  	}

  	err = -EPERM;

  	if (sock->type == SOCK_RAW && !kern &&
  	    !ns_capable(net->user_ns, CAP_NET_RAW))

  		goto out_rcu_unlock;

  
  	sock->ops = answer->ops;
  	answer_prot = answer->prot;

  	answer_flags = answer->flags;
  	rcu_read_unlock();

  	WARN_ON(!answer_prot->slab);

  
  	err = -ENOBUFS;

  	sk = sk_alloc(net, PF_INET, GFP_KERNEL, answer_prot, kern);

  	if (!sk)

  		goto out;
  
  	err = 0;

  	if (INET_PROTOSW_REUSE & answer_flags)

  		sk->sk_reuse = SK_CAN_REUSE;

  
  	inet = inet_sk(sk);

  	inet->is_icsk = (INET_PROTOSW_ICSK & answer_flags) != 0;

  	inet->nodefrag = 0;

  	if (SOCK_RAW == sock->type) {

  		inet->inet_num = protocol;

  		if (IPPROTO_RAW == protocol)
  			inet->hdrincl = 1;
  	}

  	if (net->ipv4.sysctl_ip_no_pmtu_disc)

  		inet->pmtudisc = IP_PMTUDISC_DONT;
  	else
  		inet->pmtudisc = IP_PMTUDISC_WANT;

  	inet->inet_id = 0;

  
  	sock_init_data(sock, sk);
  
  	sk->sk_destruct	   = inet_sock_destruct;

  	sk->sk_protocol	   = protocol;
  	sk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
  
  	inet->uc_ttl	= -1;
  	inet->mc_loop	= 1;
  	inet->mc_ttl	= 1;

  	inet->mc_all	= 1;

  	inet->mc_index	= 0;
  	inet->mc_list	= NULL;

  	inet->rcv_tos	= 0;

  	sk_refcnt_debug_inc(sk);

  	if (inet->inet_num) {

  		/* It assumes that any protocol which allows
  		 * the user to assign a number at socket
  		 * creation time automatically
  		 * shares.
  		 */

  		inet->inet_sport = htons(inet->inet_num);

  		/* Add to protocol hash chains. */

  		err = sk->sk_prot->hash(sk);
  		if (err) {
  			sk_common_release(sk);
  			goto out;
  		}

  	}
  
  	if (sk->sk_prot->init) {
  		err = sk->sk_prot->init(sk);

  		if (err) {
  			sk_common_release(sk);
  			goto out;
  		}
  	}
  
  	if (!kern) {
  		err = BPF_CGROUP_RUN_PROG_INET_SOCK(sk);
  		if (err) {

  			sk_common_release(sk);

  			goto out;
  		}

  	}
  out:
  	return err;
  out_rcu_unlock:
  	rcu_read_unlock();
  	goto out;
  }
  
  
  /*
   *	The peer socket should always be NULL (or else). When we call this
   *	function we are destroying the object and from then on nobody
   *	should refer to it.
   */
  int inet_release(struct socket *sock)
  {
  	struct sock *sk = sock->sk;
  
  	if (sk) {
  		long timeout;
  
  		/* Applications forget to leave groups before exiting */
  		ip_mc_drop_socket(sk);
  
  		/* If linger is set, we don't return until the close
  		 * is complete.  Otherwise we return immediately. The
  		 * actually closing is done the same either way.
  		 *
  		 * If the close is due to the process exiting, we never
  		 * linger..
  		 */
  		timeout = 0;
  		if (sock_flag(sk, SOCK_LINGER) &&
  		    !(current->flags & PF_EXITING))
  			timeout = sk->sk_lingertime;
  		sock->sk = NULL;
  		sk->sk_prot->close(sk, timeout);
  	}
  	return 0;
  }

  EXPORT_SYMBOL(inet_release);

  int inet_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
  {
  	struct sockaddr_in *addr = (struct sockaddr_in *)uaddr;
  	struct sock *sk = sock->sk;
  	struct inet_sock *inet = inet_sk(sk);

  	struct net *net = sock_net(sk);

  	unsigned short snum;
  	int chk_addr_ret;

  	u32 tb_id = RT_TABLE_LOCAL;

  	int err;
  
  	/* If the socket has its own bind function then use it. (RAW) */
  	if (sk->sk_prot->bind) {
  		err = sk->sk_prot->bind(sk, uaddr, addr_len);
  		goto out;
  	}
  	err = -EINVAL;
  	if (addr_len < sizeof(struct sockaddr_in))
  		goto out;

  	if (addr->sin_family != AF_INET) {

  		/* Compatibility games : accept AF_UNSPEC (mapped to AF_INET)
  		 * only if s_addr is INADDR_ANY.
  		 */

  		err = -EAFNOSUPPORT;

  		if (addr->sin_family != AF_UNSPEC ||
  		    addr->sin_addr.s_addr != htonl(INADDR_ANY))
  			goto out;

  	}

  	tb_id = l3mdev_fib_table_by_index(net, sk->sk_bound_dev_if) ? : tb_id;

  	chk_addr_ret = inet_addr_type_table(net, addr->sin_addr.s_addr, tb_id);

  
  	/* Not specified by any standard per-se, however it breaks too
  	 * many applications when removed.  It is unfortunate since
  	 * allowing applications to make a non-local bind solves
  	 * several problems with systems using dynamic addressing.
  	 * (ie. your servers still start up even if your ISDN link
  	 *  is temporarily down)
  	 */
  	err = -EADDRNOTAVAIL;

  	if (!net->ipv4.sysctl_ip_nonlocal_bind &&

  	    !(inet->freebind || inet->transparent) &&

  	    addr->sin_addr.s_addr != htonl(INADDR_ANY) &&

  	    chk_addr_ret != RTN_LOCAL &&
  	    chk_addr_ret != RTN_MULTICAST &&
  	    chk_addr_ret != RTN_BROADCAST)
  		goto out;
  
  	snum = ntohs(addr->sin_port);
  	err = -EACCES;

  	if (snum && snum < inet_prot_sock(net) &&

  	    !ns_capable(net->user_ns, CAP_NET_BIND_SERVICE))

  		goto out;
  
  	/*      We keep a pair of addresses. rcv_saddr is the one
  	 *      used by hash lookups, and saddr is used for transmit.
  	 *
  	 *      In the BSD API these are the same except where it
  	 *      would be illegal to use them (multicast/broadcast) in
  	 *      which case the sending device address is used.
  	 */
  	lock_sock(sk);
  
  	/* Check these errors (active socket, double bind). */
  	err = -EINVAL;

  	if (sk->sk_state != TCP_CLOSE || inet->inet_num)

  		goto out_release_sock;

  	inet->inet_rcv_saddr = inet->inet_saddr = addr->sin_addr.s_addr;

  	if (chk_addr_ret == RTN_MULTICAST || chk_addr_ret == RTN_BROADCAST)

  		inet->inet_saddr = 0;  /* Use device */

  
  	/* Make sure we are allowed to bind here. */

  	if ((snum || !inet->bind_address_no_port) &&
  	    sk->sk_prot->get_port(sk, snum)) {

  		inet->inet_saddr = inet->inet_rcv_saddr = 0;

  		err = -EADDRINUSE;
  		goto out_release_sock;
  	}

  	if (inet->inet_rcv_saddr)

  		sk->sk_userlocks |= SOCK_BINDADDR_LOCK;
  	if (snum)
  		sk->sk_userlocks |= SOCK_BINDPORT_LOCK;

  	inet->inet_sport = htons(inet->inet_num);
  	inet->inet_daddr = 0;
  	inet->inet_dport = 0;

  	sk_dst_reset(sk);
  	err = 0;
  out_release_sock:
  	release_sock(sk);
  out:
  	return err;
  }

  EXPORT_SYMBOL(inet_bind);

  int inet_dgram_connect(struct socket *sock, struct sockaddr *uaddr,

  		       int addr_len, int flags)
  {
  	struct sock *sk = sock->sk;

  	if (addr_len < sizeof(uaddr->sa_family))
  		return -EINVAL;

  	if (uaddr->sa_family == AF_UNSPEC)
  		return sk->sk_prot->disconnect(sk, flags);

  	if (!inet_sk(sk)->inet_num && inet_autobind(sk))

  		return -EAGAIN;

  	return sk->sk_prot->connect(sk, uaddr, addr_len);

  }

  EXPORT_SYMBOL(inet_dgram_connect);

  static long inet_wait_for_connect(struct sock *sk, long timeo, int writebias)

  {

  	DEFINE_WAIT_FUNC(wait, woken_wake_function);

  	add_wait_queue(sk_sleep(sk), &wait);

  	sk->sk_write_pending += writebias;

  
  	/* Basic assumption: if someone sets sk->sk_err, he _must_
  	 * change state of the socket from TCP_SYN_*.
  	 * Connect() does not allow to get error notifications
  	 * without closing the socket.
  	 */
  	while ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
  		release_sock(sk);

  		timeo = wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);

  		lock_sock(sk);
  		if (signal_pending(current) || !timeo)
  			break;

  	}

  	remove_wait_queue(sk_sleep(sk), &wait);

  	sk->sk_write_pending -= writebias;

  	return timeo;
  }
  
  /*
   *	Connect to a remote host. There is regrettably still a little
   *	TCP 'magic' in here.
   */

  int __inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,

  			  int addr_len, int flags, int is_sendmsg)

  {
  	struct sock *sk = sock->sk;
  	int err;
  	long timeo;

  	/*
  	 * uaddr can be NULL and addr_len can be 0 if:
  	 * sk is a TCP fastopen active socket and
  	 * TCP_FASTOPEN_CONNECT sockopt is set and
  	 * we already have a valid cookie for this socket.
  	 * In this case, user can call write() after connect().
  	 * write() will invoke tcp_sendmsg_fastopen() which calls
  	 * __inet_stream_connect().
  	 */
  	if (uaddr) {
  		if (addr_len < sizeof(uaddr->sa_family))
  			return -EINVAL;

  		if (uaddr->sa_family == AF_UNSPEC) {
  			err = sk->sk_prot->disconnect(sk, flags);
  			sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;
  			goto out;
  		}

  	}
  
  	switch (sock->state) {
  	default:
  		err = -EINVAL;
  		goto out;
  	case SS_CONNECTED:
  		err = -EISCONN;
  		goto out;
  	case SS_CONNECTING:

  		if (inet_sk(sk)->defer_connect)

  			err = is_sendmsg ? -EINPROGRESS : -EISCONN;

  		else
  			err = -EALREADY;

  		/* Fall out of switch with err, set for this state */
  		break;
  	case SS_UNCONNECTED:
  		err = -EISCONN;
  		if (sk->sk_state != TCP_CLOSE)
  			goto out;
  
  		err = sk->sk_prot->connect(sk, uaddr, addr_len);
  		if (err < 0)
  			goto out;

  		sock->state = SS_CONNECTING;

  		if (!err && inet_sk(sk)->defer_connect)
  			goto out;

  		/* Just entered SS_CONNECTING state; the only
  		 * difference is that return value in non-blocking
  		 * case is EINPROGRESS, rather than EALREADY.
  		 */
  		err = -EINPROGRESS;
  		break;
  	}
  
  	timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
  
  	if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {

  		int writebias = (sk->sk_protocol == IPPROTO_TCP) &&
  				tcp_sk(sk)->fastopen_req &&
  				tcp_sk(sk)->fastopen_req->data ? 1 : 0;

  		/* Error code is set above */

  		if (!timeo || !inet_wait_for_connect(sk, timeo, writebias))

  			goto out;
  
  		err = sock_intr_errno(timeo);
  		if (signal_pending(current))
  			goto out;
  	}
  
  	/* Connection was closed by RST, timeout, ICMP error
  	 * or another process disconnected us.
  	 */
  	if (sk->sk_state == TCP_CLOSE)
  		goto sock_error;
  
  	/* sk->sk_err may be not zero now, if RECVERR was ordered by user
  	 * and error was received after socket entered established state.
  	 * Hence, it is handled normally after connect() return successfully.
  	 */
  
  	sock->state = SS_CONNECTED;
  	err = 0;
  out:

  	return err;
  
  sock_error:
  	err = sock_error(sk) ? : -ECONNABORTED;
  	sock->state = SS_UNCONNECTED;
  	if (sk->sk_prot->disconnect(sk, flags))
  		sock->state = SS_DISCONNECTING;
  	goto out;
  }

  EXPORT_SYMBOL(__inet_stream_connect);
  
  int inet_stream_connect(struct socket *sock, struct sockaddr *uaddr,
  			int addr_len, int flags)
  {
  	int err;
  
  	lock_sock(sock->sk);

  	err = __inet_stream_connect(sock, uaddr, addr_len, flags, 0);

  	release_sock(sock->sk);
  	return err;
  }

  EXPORT_SYMBOL(inet_stream_connect);

  
  /*
   *	Accept a pending connection. The TCP layer now gives BSD semantics.
   */

  int inet_accept(struct socket *sock, struct socket *newsock, int flags,
  		bool kern)

  {
  	struct sock *sk1 = sock->sk;
  	int err = -EINVAL;

  	struct sock *sk2 = sk1->sk_prot->accept(sk1, flags, &err, kern);

  
  	if (!sk2)
  		goto do_err;
  
  	lock_sock(sk2);

  	sock_rps_record_flow(sk2);

  	WARN_ON(!((1 << sk2->sk_state) &

  		  (TCPF_ESTABLISHED | TCPF_SYN_RECV |
  		  TCPF_CLOSE_WAIT | TCPF_CLOSE)));

  
  	sock_graft(sk2, newsock);
  
  	newsock->state = SS_CONNECTED;
  	err = 0;
  	release_sock(sk2);
  do_err:
  	return err;
  }

  EXPORT_SYMBOL(inet_accept);

  
  
  /*
   *	This does both peername and sockname.
   */
  int inet_getname(struct socket *sock, struct sockaddr *uaddr,
  			int *uaddr_len, int peer)
  {
  	struct sock *sk		= sock->sk;
  	struct inet_sock *inet	= inet_sk(sk);

  	DECLARE_SOCKADDR(struct sockaddr_in *, sin, uaddr);

  
  	sin->sin_family = AF_INET;
  	if (peer) {

  		if (!inet->inet_dport ||

  		    (((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_SYN_SENT)) &&
  		     peer == 1))
  			return -ENOTCONN;

  		sin->sin_port = inet->inet_dport;
  		sin->sin_addr.s_addr = inet->inet_daddr;

  	} else {

  		__be32 addr = inet->inet_rcv_saddr;

  		if (!addr)

  			addr = inet->inet_saddr;
  		sin->sin_port = inet->inet_sport;

  		sin->sin_addr.s_addr = addr;
  	}
  	memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
  	*uaddr_len = sizeof(*sin);
  	return 0;
  }

  EXPORT_SYMBOL(inet_getname);

  int inet_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)

  {
  	struct sock *sk = sock->sk;

  	sock_rps_record_flow(sk);

  	/* We may need to bind the socket. */

  	if (!inet_sk(sk)->inet_num && !sk->sk_prot->no_autobind &&
  	    inet_autobind(sk))

  		return -EAGAIN;

  	return sk->sk_prot->sendmsg(sk, msg, size);

  }

  EXPORT_SYMBOL(inet_sendmsg);

  ssize_t inet_sendpage(struct socket *sock, struct page *page, int offset,
  		      size_t size, int flags)

  {
  	struct sock *sk = sock->sk;

  	sock_rps_record_flow(sk);

  	/* We may need to bind the socket. */

  	if (!inet_sk(sk)->inet_num && !sk->sk_prot->no_autobind &&
  	    inet_autobind(sk))

  		return -EAGAIN;
  
  	if (sk->sk_prot->sendpage)
  		return sk->sk_prot->sendpage(sk, page, offset, size, flags);
  	return sock_no_sendpage(sock, page, offset, size, flags);
  }

  EXPORT_SYMBOL(inet_sendpage);

  int inet_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
  		 int flags)

  {
  	struct sock *sk = sock->sk;
  	int addr_len = 0;
  	int err;

  	sock_rps_record_flow(sk);

  	err = sk->sk_prot->recvmsg(sk, msg, size, flags & MSG_DONTWAIT,

  				   flags & ~MSG_DONTWAIT, &addr_len);
  	if (err >= 0)
  		msg->msg_namelen = addr_len;
  	return err;
  }
  EXPORT_SYMBOL(inet_recvmsg);

  
  int inet_shutdown(struct socket *sock, int how)
  {
  	struct sock *sk = sock->sk;
  	int err = 0;
  
  	/* This should really check to make sure
  	 * the socket is a TCP socket. (WHY AC...)
  	 */
  	how++; /* maps 0->1 has the advantage of making bit 1 rcvs and
  		       1->2 bit 2 snds.
  		       2->3 */
  	if ((how & ~SHUTDOWN_MASK) || !how)	/* MAXINT->0 */
  		return -EINVAL;
  
  	lock_sock(sk);
  	if (sock->state == SS_CONNECTING) {
  		if ((1 << sk->sk_state) &
  		    (TCPF_SYN_SENT | TCPF_SYN_RECV | TCPF_CLOSE))
  			sock->state = SS_DISCONNECTING;
  		else
  			sock->state = SS_CONNECTED;
  	}
  
  	switch (sk->sk_state) {
  	case TCP_CLOSE:
  		err = -ENOTCONN;
  		/* Hack to wake up other listeners, who can poll for
  		   POLLHUP, even on eg. unconnected UDP sockets -- RR */
  	default:
  		sk->sk_shutdown |= how;
  		if (sk->sk_prot->shutdown)
  			sk->sk_prot->shutdown(sk, how);
  		break;
  
  	/* Remaining two branches are temporary solution for missing
  	 * close() in multithreaded environment. It is _not_ a good idea,
  	 * but we have no choice until close() is repaired at VFS level.
  	 */
  	case TCP_LISTEN:
  		if (!(how & RCV_SHUTDOWN))
  			break;
  		/* Fall through */
  	case TCP_SYN_SENT:
  		err = sk->sk_prot->disconnect(sk, O_NONBLOCK);
  		sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;
  		break;
  	}
  
  	/* Wake up anyone sleeping in poll. */
  	sk->sk_state_change(sk);
  	release_sock(sk);
  	return err;
  }

  EXPORT_SYMBOL(inet_shutdown);

  
  /*
   *	ioctl() calls you can issue on an INET socket. Most of these are
   *	device configuration and stuff and very rarely used. Some ioctls
   *	pass on to the socket itself.
   *
   *	NOTE: I like the idea of a module for the config stuff. ie ifconfig
   *	loads the devconfigure module does its configuring and unloads it.
   *	There's a good 20K of config code hanging around the kernel.
   */
  
  int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
  {
  	struct sock *sk = sock->sk;
  	int err = 0;

  	struct net *net = sock_net(sk);

  
  	switch (cmd) {

  	case SIOCGSTAMP:
  		err = sock_get_timestamp(sk, (struct timeval __user *)arg);
  		break;
  	case SIOCGSTAMPNS:
  		err = sock_get_timestampns(sk, (struct timespec __user *)arg);
  		break;
  	case SIOCADDRT:
  	case SIOCDELRT:
  	case SIOCRTMSG:
  		err = ip_rt_ioctl(net, cmd, (void __user *)arg);
  		break;
  	case SIOCDARP:
  	case SIOCGARP:
  	case SIOCSARP:
  		err = arp_ioctl(net, cmd, (void __user *)arg);
  		break;
  	case SIOCGIFADDR:
  	case SIOCSIFADDR:
  	case SIOCGIFBRDADDR:
  	case SIOCSIFBRDADDR:
  	case SIOCGIFNETMASK:
  	case SIOCSIFNETMASK:
  	case SIOCGIFDSTADDR:
  	case SIOCSIFDSTADDR:
  	case SIOCSIFPFLAGS:
  	case SIOCGIFPFLAGS:
  	case SIOCSIFFLAGS:
  		err = devinet_ioctl(net, cmd, (void __user *)arg);
  		break;
  	default:
  		if (sk->sk_prot->ioctl)
  			err = sk->sk_prot->ioctl(sk, cmd, arg);
  		else
  			err = -ENOIOCTLCMD;
  		break;

  	}
  	return err;
  }

  EXPORT_SYMBOL(inet_ioctl);

  #ifdef CONFIG_COMPAT

  static int inet_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)

  {
  	struct sock *sk = sock->sk;
  	int err = -ENOIOCTLCMD;
  
  	if (sk->sk_prot->compat_ioctl)
  		err = sk->sk_prot->compat_ioctl(sk, cmd, arg);
  
  	return err;
  }
  #endif

  const struct proto_ops inet_stream_ops = {

  	.family		   = PF_INET,
  	.owner		   = THIS_MODULE,
  	.release	   = inet_release,
  	.bind		   = inet_bind,
  	.connect	   = inet_stream_connect,
  	.socketpair	   = sock_no_socketpair,
  	.accept		   = inet_accept,
  	.getname	   = inet_getname,
  	.poll		   = tcp_poll,
  	.ioctl		   = inet_ioctl,
  	.listen		   = inet_listen,
  	.shutdown	   = inet_shutdown,
  	.setsockopt	   = sock_common_setsockopt,
  	.getsockopt	   = sock_common_getsockopt,

  	.sendmsg	   = inet_sendmsg,

  	.recvmsg	   = inet_recvmsg,

  	.mmap		   = sock_no_mmap,

  	.sendpage	   = inet_sendpage,

  	.splice_read	   = tcp_splice_read,

  	.read_sock	   = tcp_read_sock,

  	.sendmsg_locked    = tcp_sendmsg_locked,
  	.sendpage_locked   = tcp_sendpage_locked,

  	.peek_len	   = tcp_peek_len,

  #ifdef CONFIG_COMPAT

  	.compat_setsockopt = compat_sock_common_setsockopt,
  	.compat_getsockopt = compat_sock_common_getsockopt,

  	.compat_ioctl	   = inet_compat_ioctl,

  #endif

  };

  EXPORT_SYMBOL(inet_stream_ops);

  const struct proto_ops inet_dgram_ops = {

  	.family		   = PF_INET,
  	.owner		   = THIS_MODULE,
  	.release	   = inet_release,
  	.bind		   = inet_bind,
  	.connect	   = inet_dgram_connect,
  	.socketpair	   = sock_no_socketpair,
  	.accept		   = sock_no_accept,
  	.getname	   = inet_getname,
  	.poll		   = udp_poll,
  	.ioctl		   = inet_ioctl,
  	.listen		   = sock_no_listen,
  	.shutdown	   = inet_shutdown,
  	.setsockopt	   = sock_common_setsockopt,
  	.getsockopt	   = sock_common_getsockopt,
  	.sendmsg	   = inet_sendmsg,

  	.recvmsg	   = inet_recvmsg,

  	.mmap		   = sock_no_mmap,
  	.sendpage	   = inet_sendpage,

  	.set_peek_off	   = sk_set_peek_off,

  #ifdef CONFIG_COMPAT

  	.compat_setsockopt = compat_sock_common_setsockopt,
  	.compat_getsockopt = compat_sock_common_getsockopt,

  	.compat_ioctl	   = inet_compat_ioctl,

  #endif

  };

  EXPORT_SYMBOL(inet_dgram_ops);

  
  /*
   * For SOCK_RAW sockets; should be the same as inet_dgram_ops but without
   * udp_poll
   */

  static const struct proto_ops inet_sockraw_ops = {

  	.family		   = PF_INET,
  	.owner		   = THIS_MODULE,
  	.release	   = inet_release,
  	.bind		   = inet_bind,
  	.connect	   = inet_dgram_connect,
  	.socketpair	   = sock_no_socketpair,
  	.accept		   = sock_no_accept,
  	.getname	   = inet_getname,
  	.poll		   = datagram_poll,
  	.ioctl		   = inet_ioctl,
  	.listen		   = sock_no_listen,
  	.shutdown	   = inet_shutdown,
  	.setsockopt	   = sock_common_setsockopt,
  	.getsockopt	   = sock_common_getsockopt,
  	.sendmsg	   = inet_sendmsg,

  	.recvmsg	   = inet_recvmsg,

  	.mmap		   = sock_no_mmap,
  	.sendpage	   = inet_sendpage,

  #ifdef CONFIG_COMPAT

  	.compat_setsockopt = compat_sock_common_setsockopt,
  	.compat_getsockopt = compat_sock_common_getsockopt,

  	.compat_ioctl	   = inet_compat_ioctl,

  #endif

  };

  static const struct net_proto_family inet_family_ops = {

  	.family = PF_INET,
  	.create = inet_create,
  	.owner	= THIS_MODULE,
  };

  /* Upon startup we insert all the elements in inetsw_array[] into
   * the linked list inetsw.
   */
  static struct inet_protosw inetsw_array[] =
  {

  	{
  		.type =       SOCK_STREAM,
  		.protocol =   IPPROTO_TCP,
  		.prot =       &tcp_prot,
  		.ops =        &inet_stream_ops,

  		.flags =      INET_PROTOSW_PERMANENT |

  			      INET_PROTOSW_ICSK,

  	},
  
  	{
  		.type =       SOCK_DGRAM,
  		.protocol =   IPPROTO_UDP,
  		.prot =       &udp_prot,
  		.ops =        &inet_dgram_ops,

  		.flags =      INET_PROTOSW_PERMANENT,

         },

         {
  		.type =       SOCK_DGRAM,
  		.protocol =   IPPROTO_ICMP,
  		.prot =       &ping_prot,

  		.ops =        &inet_sockraw_ops,

  		.flags =      INET_PROTOSW_REUSE,
         },

  
         {

  	       .type =       SOCK_RAW,
  	       .protocol =   IPPROTO_IP,	/* wild card */
  	       .prot =       &raw_prot,
  	       .ops =        &inet_sockraw_ops,

  	       .flags =      INET_PROTOSW_REUSE,

         }
  };

  #define INETSW_ARRAY_LEN ARRAY_SIZE(inetsw_array)

  
  void inet_register_protosw(struct inet_protosw *p)
  {
  	struct list_head *lh;
  	struct inet_protosw *answer;
  	int protocol = p->protocol;
  	struct list_head *last_perm;
  
  	spin_lock_bh(&inetsw_lock);
  
  	if (p->type >= SOCK_MAX)
  		goto out_illegal;
  
  	/* If we are trying to override a permanent protocol, bail. */

  	last_perm = &inetsw[p->type];
  	list_for_each(lh, &inetsw[p->type]) {
  		answer = list_entry(lh, struct inet_protosw, list);

  		/* Check only the non-wild match. */

  		if ((INET_PROTOSW_PERMANENT & answer->flags) == 0)
  			break;
  		if (protocol == answer->protocol)
  			goto out_permanent;
  		last_perm = lh;

  	}

  
  	/* Add the new entry after the last permanent entry if any, so that
  	 * the new entry does not override a permanent entry when matched with
  	 * a wild-card protocol. But it is allowed to override any existing

  	 * non-permanent entry.  This means that when we remove this entry, the

  	 * system automatically returns to the old behavior.
  	 */
  	list_add_rcu(&p->list, last_perm);
  out:
  	spin_unlock_bh(&inetsw_lock);

  	return;
  
  out_permanent:

  	pr_err("Attempt to override permanent protocol %d
  ", protocol);

  	goto out;
  
  out_illegal:

  	pr_err("Ignoring attempt to register invalid socket type %d
  ",

  	       p->type);
  	goto out;
  }

  EXPORT_SYMBOL(inet_register_protosw);

  
  void inet_unregister_protosw(struct inet_protosw *p)
  {
  	if (INET_PROTOSW_PERMANENT & p->flags) {

  		pr_err("Attempt to unregister permanent protocol %d
  ",

  		       p->protocol);
  	} else {
  		spin_lock_bh(&inetsw_lock);
  		list_del_rcu(&p->list);
  		spin_unlock_bh(&inetsw_lock);
  
  		synchronize_net();
  	}
  }

  EXPORT_SYMBOL(inet_unregister_protosw);

  static int inet_sk_reselect_saddr(struct sock *sk)
  {
  	struct inet_sock *inet = inet_sk(sk);

  	__be32 old_saddr = inet->inet_saddr;

  	__be32 daddr = inet->inet_daddr;

  	struct flowi4 *fl4;

  	struct rtable *rt;
  	__be32 new_saddr;

  	struct ip_options_rcu *inet_opt;

  	inet_opt = rcu_dereference_protected(inet->inet_opt,

  					     lockdep_sock_is_held(sk));

  	if (inet_opt && inet_opt->opt.srr)
  		daddr = inet_opt->opt.faddr;

  
  	/* Query new route. */

  	fl4 = &inet->cork.fl.u.ip4;
  	rt = ip_route_connect(fl4, daddr, 0, RT_CONN_FLAGS(sk),

  			      sk->sk_bound_dev_if, sk->sk_protocol,

  			      inet->inet_sport, inet->inet_dport, sk);

  	if (IS_ERR(rt))
  		return PTR_ERR(rt);

  	sk_setup_caps(sk, &rt->dst);

  	new_saddr = fl4->saddr;

  
  	if (new_saddr == old_saddr)
  		return 0;

  	if (sock_net(sk)->ipv4.sysctl_ip_dynaddr > 1) {

  		pr_info("%s(): shifting inet->saddr from %pI4 to %pI4
  ",
  			__func__, &old_saddr, &new_saddr);

  	}

  	inet->inet_saddr = inet->inet_rcv_saddr = new_saddr;

  
  	/*
  	 * XXX The only one ugly spot where we need to
  	 * XXX really change the sockets identity after
  	 * XXX it has entered the hashes. -DaveM
  	 *
  	 * Besides that, it does not check for connection
  	 * uniqueness. Wait for troubles.
  	 */

  	return __sk_prot_rehash(sk);

  }
  
  int inet_sk_rebuild_header(struct sock *sk)
  {
  	struct inet_sock *inet = inet_sk(sk);
  	struct rtable *rt = (struct rtable *)__sk_dst_check(sk, 0);

  	__be32 daddr;

  	struct ip_options_rcu *inet_opt;

  	struct flowi4 *fl4;

  	int err;
  
  	/* Route is OK, nothing to do. */
  	if (rt)
  		return 0;
  
  	/* Reroute. */

  	rcu_read_lock();
  	inet_opt = rcu_dereference(inet->inet_opt);

  	daddr = inet->inet_daddr;

  	if (inet_opt && inet_opt->opt.srr)
  		daddr = inet_opt->opt.faddr;
  	rcu_read_unlock();

  	fl4 = &inet->cork.fl.u.ip4;
  	rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr, inet->inet_saddr,

  				   inet->inet_dport, inet->inet_sport,
  				   sk->sk_protocol, RT_CONN_FLAGS(sk),
  				   sk->sk_bound_dev_if);

  	if (!IS_ERR(rt)) {
  		err = 0;

  		sk_setup_caps(sk, &rt->dst);

  	} else {
  		err = PTR_ERR(rt);

  		/* Routing failed... */
  		sk->sk_route_caps = 0;
  		/*
  		 * Other protocols have to map its equivalent state to TCP_SYN_SENT.
  		 * DCCP maps its DCCP_REQUESTING state to TCP_SYN_SENT. -acme
  		 */

  		if (!sock_net(sk)->ipv4.sysctl_ip_dynaddr ||

  		    sk->sk_state != TCP_SYN_SENT ||
  		    (sk->sk_userlocks & SOCK_BINDADDR_LOCK) ||
  		    (err = inet_sk_reselect_saddr(sk)) != 0)
  			sk->sk_err_soft = -err;
  	}
  
  	return err;
  }

  EXPORT_SYMBOL(inet_sk_rebuild_header);

  struct sk_buff *inet_gso_segment(struct sk_buff *skb,
  				 netdev_features_t features)

  {

  	bool udpfrag = false, fixedid = false, gso_partial, encap;

  	struct sk_buff *segs = ERR_PTR(-EINVAL);

  	const struct net_offload *ops;

  	unsigned int offset = 0;

  	struct iphdr *iph;

  	int proto, tot_len;

  	int nhoff;

  	int ihl;
  	int id;

  	skb_reset_network_header(skb);
  	nhoff = skb_network_header(skb) - skb_mac_header(skb);

  	if (unlikely(!pskb_may_pull(skb, sizeof(*iph))))

  		goto out;

  	iph = ip_hdr(skb);

  	ihl = iph->ihl * 4;
  	if (ihl < sizeof(*iph))
  		goto out;

  	id = ntohs(iph->id);
  	proto = iph->protocol;
  
  	/* Warning: after this point, iph might be no longer valid */

  	if (unlikely(!pskb_may_pull(skb, ihl)))

  		goto out;

  	__skb_pull(skb, ihl);

  	encap = SKB_GSO_CB(skb)->encap_level > 0;
  	if (encap)

  		features &= skb->dev->hw_enc_features;

  	SKB_GSO_CB(skb)->encap_level += ihl;

  	skb_reset_transport_header(skb);

  	segs = ERR_PTR(-EPROTONOSUPPORT);

  	if (!skb->encapsulation || encap) {

  		udpfrag = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);

  		fixedid = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TCP_FIXEDID);
  
  		/* fixed ID is invalid if DF bit is not set */

  		if (fixedid && !(ip_hdr(skb)->frag_off & htons(IP_DF)))

  			goto out;
  	}

  	ops = rcu_dereference(inet_offloads[proto]);

  	if (likely(ops && ops->callbacks.gso_segment))
  		segs = ops->callbacks.gso_segment(skb, features);

  	if (IS_ERR_OR_NULL(segs))

  		goto out;

  	gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);

  	skb = segs;
  	do {

  		iph = (struct iphdr *)(skb_mac_header(skb) + nhoff);

  		if (udpfrag) {
  			iph->frag_off = htons(offset >> 3);
  			if (skb->next)
  				iph->frag_off |= htons(IP_MF);
  			offset += skb->len - nhoff - ihl;
  			tot_len = skb->len - nhoff;
  		} else if (skb_is_gso(skb)) {

  			if (!fixedid) {
  				iph->id = htons(id);
  				id += skb_shinfo(skb)->gso_segs;
  			}

  
  			if (gso_partial)
  				tot_len = skb_shinfo(skb)->gso_size +
  					  SKB_GSO_CB(skb)->data_offset +
  					  skb->head - (unsigned char *)iph;
  			else
  				tot_len = skb->len - nhoff;

  		} else {
  			if (!fixedid)
  				iph->id = htons(id++);
  			tot_len = skb->len - nhoff;

  		}

  		iph->tot_len = htons(tot_len);

  		ip_send_check(iph);

  		if (encap)

  			skb_reset_inner_headers(skb);

  		skb->network_header = (u8 *)iph - skb->head;

  		skb_reset_mac_len(skb);

  	} while ((skb = skb->next));
  
  out:
  	return segs;
  }

  EXPORT_SYMBOL(inet_gso_segment);

  struct sk_buff **inet_gro_receive(struct sk_buff **head, struct sk_buff *skb)

  {

  	const struct net_offload *ops;

  	struct sk_buff **pp = NULL;
  	struct sk_buff *p;

  	const struct iphdr *iph;

  	unsigned int hlen;
  	unsigned int off;

  	unsigned int id;

  	int flush = 1;
  	int proto;

  	off = skb_gro_offset(skb);
  	hlen = off + sizeof(*iph);
  	iph = skb_gro_header_fast(skb, off);
  	if (skb_gro_header_hard(skb, hlen)) {
  		iph = skb_gro_header_slow(skb, hlen, off);
  		if (unlikely(!iph))
  			goto out;
  	}

  	proto = iph->protocol;

  
  	rcu_read_lock();

  	ops = rcu_dereference(inet_offloads[proto]);

  	if (!ops || !ops->callbacks.gro_receive)

  		goto out_unlock;

  	if (*(u8 *)iph != 0x45)

  		goto out_unlock;

  	if (ip_is_fragment(iph))
  		goto out_unlock;

  	if (unlikely(ip_fast_csum((u8 *)iph, 5)))

  		goto out_unlock;

  	id = ntohl(*(__be32 *)&iph->id);

  	flush = (u16)((ntohl(*(__be32 *)iph) ^ skb_gro_len(skb)) | (id & ~IP_DF));

  	id >>= 16;

  
  	for (p = *head; p; p = p->next) {
  		struct iphdr *iph2;

  		u16 flush_id;

  
  		if (!NAPI_GRO_CB(p)->same_flow)
  			continue;

  		iph2 = (struct iphdr *)(p->data + off);
  		/* The above works because, with the exception of the top
  		 * (inner most) layer, we only aggregate pkts with the same
  		 * hdr length so all the hdrs we'll need to verify will start
  		 * at the same offset.
  		 */

  		if ((iph->protocol ^ iph2->protocol) |

  		    ((__force u32)iph->saddr ^ (__force u32)iph2->saddr) |
  		    ((__force u32)iph->daddr ^ (__force u32)iph2->daddr)) {

  			NAPI_GRO_CB(p)->same_flow = 0;
  			continue;
  		}
  
  		/* All fields must match except length and checksum. */
  		NAPI_GRO_CB(p)->flush |=

  			(iph->ttl ^ iph2->ttl) |

  			(iph->tos ^ iph2->tos) |

  			((iph->frag_off ^ iph2->frag_off) & htons(IP_DF));

  
  		NAPI_GRO_CB(p)->flush |= flush;

  
  		/* We need to store of the IP ID check to be included later
  		 * when we can verify that this packet does in fact belong
  		 * to a given flow.
  		 */
  		flush_id = (u16)(id - ntohs(iph2->id));
  
  		/* This bit of code makes it much easier for us to identify
  		 * the cases where we are doing atomic vs non-atomic IP ID
  		 * checks.  Specifically an atomic check can return IP ID
  		 * values 0 - 0xFFFF, while a non-atomic check can only
  		 * return 0 or 0xFFFF.
  		 */
  		if (!NAPI_GRO_CB(p)->is_atomic ||
  		    !(iph->frag_off & htons(IP_DF))) {
  			flush_id ^= NAPI_GRO_CB(p)->count;
  			flush_id = flush_id ? 0xFFFF : 0;
  		}
  
  		/* If the previous IP ID value was based on an atomic
  		 * datagram we can overwrite the value and ignore it.
  		 */
  		if (NAPI_GRO_CB(skb)->is_atomic)
  			NAPI_GRO_CB(p)->flush_id = flush_id;
  		else
  			NAPI_GRO_CB(p)->flush_id |= flush_id;

  	}

  	NAPI_GRO_CB(skb)->is_atomic = !!(iph->frag_off & htons(IP_DF));

  	NAPI_GRO_CB(skb)->flush |= flush;

  	skb_set_network_header(skb, off);
  	/* The above will be needed by the transport layer if there is one
  	 * immediately following this IP hdr.
  	 */

  	/* Note : No need to call skb_gro_postpull_rcsum() here,
  	 * as we already checked checksum over ipv4 header was 0
  	 */

  	skb_gro_pull(skb, sizeof(*iph));
  	skb_set_transport_header(skb, skb_gro_offset(skb));

  	pp = call_gro_receive(ops->callbacks.gro_receive, head, skb);

  
  out_unlock:
  	rcu_read_unlock();
  
  out:

  	skb_gro_flush_final(skb, pp, flush);

  
  	return pp;
  }

  EXPORT_SYMBOL(inet_gro_receive);

  static struct sk_buff **ipip_gro_receive(struct sk_buff **head,
  					 struct sk_buff *skb)
  {
  	if (NAPI_GRO_CB(skb)->encap_mark) {
  		NAPI_GRO_CB(skb)->flush = 1;
  		return NULL;
  	}
  
  	NAPI_GRO_CB(skb)->encap_mark = 1;
  
  	return inet_gro_receive(head, skb);
  }

  #define SECONDS_PER_DAY	86400
  
  /* inet_current_timestamp - Return IP network timestamp
   *
   * Return milliseconds since midnight in network byte order.
   */
  __be32 inet_current_timestamp(void)
  {
  	u32 secs;
  	u32 msecs;
  	struct timespec64 ts;
  
  	ktime_get_real_ts64(&ts);
  
  	/* Get secs since midnight. */
  	(void)div_u64_rem(ts.tv_sec, SECONDS_PER_DAY, &secs);
  	/* Convert to msecs. */
  	msecs = secs * MSEC_PER_SEC;
  	/* Convert nsec to msec. */
  	msecs += (u32)ts.tv_nsec / NSEC_PER_MSEC;
  
  	/* Convert to network byte order. */

  	return htonl(msecs);

  }
  EXPORT_SYMBOL(inet_current_timestamp);

  int inet_recv_error(struct sock *sk, struct msghdr *msg, int len, int *addr_len)
  {
  	if (sk->sk_family == AF_INET)
  		return ip_recv_error(sk, msg, len, addr_len);
  #if IS_ENABLED(CONFIG_IPV6)
  	if (sk->sk_family == AF_INET6)
  		return pingv6_ops.ipv6_recv_error(sk, msg, len, addr_len);
  #endif
  	return -EINVAL;
  }

  int inet_gro_complete(struct sk_buff *skb, int nhoff)

  {

  	__be16 newlen = htons(skb->len - nhoff);
  	struct iphdr *iph = (struct iphdr *)(skb->data + nhoff);

  	const struct net_offload *ops;

  	int proto = iph->protocol;

  	int err = -ENOSYS;

  	if (skb->encapsulation) {
  		skb_set_inner_protocol(skb, cpu_to_be16(ETH_P_IP));

  		skb_set_inner_network_header(skb, nhoff);

  	}

  	csum_replace2(&iph->check, iph->tot_len, newlen);
  	iph->tot_len = newlen;
  
  	rcu_read_lock();

  	ops = rcu_dereference(inet_offloads[proto]);

  	if (WARN_ON(!ops || !ops->callbacks.gro_complete))

  		goto out_unlock;

  	/* Only need to add sizeof(*iph) to get to the next hdr below
  	 * because any hdr with option will have been flushed in
  	 * inet_gro_receive().
  	 */
  	err = ops->callbacks.gro_complete(skb, nhoff + sizeof(*iph));

  
  out_unlock:
  	rcu_read_unlock();
  
  	return err;
  }

  EXPORT_SYMBOL(inet_gro_complete);

  static int ipip_gro_complete(struct sk_buff *skb, int nhoff)
  {
  	skb->encapsulation = 1;

  	skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP4;

  	return inet_gro_complete(skb, nhoff);
  }

  int inet_ctl_sock_create(struct sock **sk, unsigned short family,

  			 unsigned short type, unsigned char protocol,
  			 struct net *net)

  {

  	struct socket *sock;

  	int rc = sock_create_kern(net, family, type, protocol, &sock);

  
  	if (rc == 0) {

  		*sk = sock->sk;
  		(*sk)->sk_allocation = GFP_ATOMIC;

  		/*
  		 * Unhash it so that IP input processing does not even see it,
  		 * we do not wish this socket to see incoming packets.
  		 */

  		(*sk)->sk_prot->unhash(*sk);

  	}
  	return rc;
  }

  EXPORT_SYMBOL_GPL(inet_ctl_sock_create);

  u64 snmp_get_cpu_field(void __percpu *mib, int cpu, int offt)
  {
  	return  *(((unsigned long *)per_cpu_ptr(mib, cpu)) + offt);
  }
  EXPORT_SYMBOL_GPL(snmp_get_cpu_field);

  unsigned long snmp_fold_field(void __percpu *mib, int offt)

  {
  	unsigned long res = 0;

  	int i;

  	for_each_possible_cpu(i)

  		res += snmp_get_cpu_field(mib, i, offt);

  	return res;
  }
  EXPORT_SYMBOL_GPL(snmp_fold_field);

  #if BITS_PER_LONG==32

  u64 snmp_get_cpu_field64(void __percpu *mib, int cpu, int offt,

  			 size_t syncp_offset)
  {
  	void *bhptr;
  	struct u64_stats_sync *syncp;
  	u64 v;
  	unsigned int start;
  
  	bhptr = per_cpu_ptr(mib, cpu);
  	syncp = (struct u64_stats_sync *)(bhptr + syncp_offset);
  	do {
  		start = u64_stats_fetch_begin_irq(syncp);
  		v = *(((u64 *)bhptr) + offt);
  	} while (u64_stats_fetch_retry_irq(syncp, start));
  
  	return v;
  }
  EXPORT_SYMBOL_GPL(snmp_get_cpu_field64);

  u64 snmp_fold_field64(void __percpu *mib, int offt, size_t syncp_offset)

  {
  	u64 res = 0;
  	int cpu;
  
  	for_each_possible_cpu(cpu) {

  		res += snmp_get_cpu_field64(mib, cpu, offt, syncp_offset);

  	}
  	return res;
  }
  EXPORT_SYMBOL_GPL(snmp_fold_field64);
  #endif

  #ifdef CONFIG_IP_MULTICAST

  static const struct net_protocol igmp_protocol = {

  	.handler =	igmp_rcv,

  	.netns_ok =	1,

  };
  #endif

  /* thinking of making this const? Don't.
   * early_demux can change based on sysctl.
   */

  static struct net_protocol tcp_protocol = {

  	.early_demux	=	tcp_v4_early_demux,

  	.early_demux_handler =  tcp_v4_early_demux,

  	.handler	=	tcp_v4_rcv,
  	.err_handler	=	tcp_v4_err,

  	.no_policy	=	1,
  	.netns_ok	=	1,

  	.icmp_strict_tag_validation = 1,

  };

  /* thinking of making this const? Don't.
   * early_demux can change based on sysctl.
   */

  static struct net_protocol udp_protocol = {

  	.early_demux =	udp_v4_early_demux,

  	.early_demux_handler =	udp_v4_early_demux,

  	.handler =	udp_rcv,
  	.err_handler =	udp_err,
  	.no_policy =	1,

  	.netns_ok =	1,

  };

  static const struct net_protocol icmp_protocol = {

  	.handler =	icmp_rcv,

  	.err_handler =	icmp_err,

  	.no_policy =	1,

  	.netns_ok =	1,

  };

  static __net_init int ipv4_mib_init_net(struct net *net)
  {

  	int i;

  	net->mib.tcp_statistics = alloc_percpu(struct tcp_mib);
  	if (!net->mib.tcp_statistics)

  		goto err_tcp_mib;

  	net->mib.ip_statistics = alloc_percpu(struct ipstats_mib);
  	if (!net->mib.ip_statistics)

  		goto err_ip_mib;

  
  	for_each_possible_cpu(i) {
  		struct ipstats_mib *af_inet_stats;

  		af_inet_stats = per_cpu_ptr(net->mib.ip_statistics, i);

  		u64_stats_init(&af_inet_stats->syncp);

  	}

  	net->mib.net_statistics = alloc_percpu(struct linux_mib);
  	if (!net->mib.net_statistics)

  		goto err_net_mib;

  	net->mib.udp_statistics = alloc_percpu(struct udp_mib);
  	if (!net->mib.udp_statistics)

  		goto err_udp_mib;

  	net->mib.udplite_statistics = alloc_percpu(struct udp_mib);
  	if (!net->mib.udplite_statistics)

  		goto err_udplite_mib;

  	net->mib.icmp_statistics = alloc_percpu(struct icmp_mib);
  	if (!net->mib.icmp_statistics)

  		goto err_icmp_mib;

  	net->mib.icmpmsg_statistics = kzalloc(sizeof(struct icmpmsg_mib),
  					      GFP_KERNEL);
  	if (!net->mib.icmpmsg_statistics)

  		goto err_icmpmsg_mib;

  
  	tcp_mib_init(net);

  	return 0;

  err_icmpmsg_mib:

  	free_percpu(net->mib.icmp_statistics);

  err_icmp_mib:

  	free_percpu(net->mib.udplite_statistics);

  err_udplite_mib:

  	free_percpu(net->mib.udp_statistics);

  err_udp_mib:

  	free_percpu(net->mib.net_statistics);

  err_net_mib:

  	free_percpu(net->mib.ip_statistics);

  err_ip_mib:

  	free_percpu(net->mib.tcp_statistics);

  err_tcp_mib:
  	return -ENOMEM;

  }
  
  static __net_exit void ipv4_mib_exit_net(struct net *net)
  {

  	kfree(net->mib.icmpmsg_statistics);

  	free_percpu(net->mib.icmp_statistics);
  	free_percpu(net->mib.udplite_statistics);
  	free_percpu(net->mib.udp_statistics);
  	free_percpu(net->mib.net_statistics);
  	free_percpu(net->mib.ip_statistics);
  	free_percpu(net->mib.tcp_statistics);

  }
  
  static __net_initdata struct pernet_operations ipv4_mib_ops = {
  	.init = ipv4_mib_init_net,
  	.exit = ipv4_mib_exit_net,
  };

  static int __init init_ipv4_mibs(void)
  {

  	return register_pernet_subsys(&ipv4_mib_ops);

  }

  static __net_init int inet_init_net(struct net *net)
  {
  	/*
  	 * Set defaults for local port range
  	 */
  	seqlock_init(&net->ipv4.ip_local_ports.lock);
  	net->ipv4.ip_local_ports.range[0] =  32768;

  	net->ipv4.ip_local_ports.range[1] =  60999;

  
  	seqlock_init(&net->ipv4.ping_group_range.lock);
  	/*
  	 * Sane defaults - nobody may create ping sockets.
  	 * Boot scripts should set this to distro-specific group.
  	 */
  	net->ipv4.ping_group_range.range[0] = make_kgid(&init_user_ns, 1);
  	net->ipv4.ping_group_range.range[1] = make_kgid(&init_user_ns, 0);

  
  	/* Default values for sysctl-controlled parameters.
  	 * We set them here, in case sysctl is not compiled.
  	 */
  	net->ipv4.sysctl_ip_default_ttl = IPDEFTTL;
  	net->ipv4.sysctl_ip_dynaddr = 0;
  	net->ipv4.sysctl_ip_early_demux = 1;

  	net->ipv4.sysctl_udp_early_demux = 1;
  	net->ipv4.sysctl_tcp_early_demux = 1;

  #ifdef CONFIG_SYSCTL
  	net->ipv4.sysctl_ip_prot_sock = PROT_SOCK;
  #endif

  	/* Some igmp sysctl, whose values are always used */
  	net->ipv4.sysctl_igmp_max_memberships = 20;
  	net->ipv4.sysctl_igmp_max_msf = 10;
  	/* IGMP reports for link-local multicast groups are enabled by default */
  	net->ipv4.sysctl_igmp_llm_reports = 1;
  	net->ipv4.sysctl_igmp_qrv = 2;

  	return 0;
  }
  
  static __net_exit void inet_exit_net(struct net *net)
  {
  }
  
  static __net_initdata struct pernet_operations af_inet_ops = {
  	.init = inet_init_net,
  	.exit = inet_exit_net,
  };
  
  static int __init init_inet_pernet_ops(void)
  {
  	return register_pernet_subsys(&af_inet_ops);
  }

  static int ipv4_proc_init(void);

  /*
   *	IP protocol layer initialiser
   */

  static struct packet_offload ip_packet_offload __read_mostly = {
  	.type = cpu_to_be16(ETH_P_IP),

  	.callbacks = {

  		.gso_segment = inet_gso_segment,
  		.gro_receive = inet_gro_receive,
  		.gro_complete = inet_gro_complete,
  	},

  };

  static const struct net_offload ipip_offload = {
  	.callbacks = {

  		.gso_segment	= inet_gso_segment,

  		.gro_receive	= ipip_gro_receive,

  		.gro_complete	= ipip_gro_complete,

  	},
  };

  static int __init ipip_offload_init(void)
  {
  	return inet_add_offload(&ipip_offload, IPPROTO_IPIP);
  }

  static int __init ipv4_offload_init(void)
  {
  	/*
  	 * Add offloads
  	 */

  	if (udpv4_offload_init() < 0)

  		pr_crit("%s: Cannot add UDP protocol offload
  ", __func__);

  	if (tcpv4_offload_init() < 0)
  		pr_crit("%s: Cannot add TCP protocol offload
  ", __func__);

  	if (ipip_offload_init() < 0)
  		pr_crit("%s: Cannot add IPIP protocol offload
  ", __func__);

  
  	dev_add_offload(&ip_packet_offload);
  	return 0;
  }
  
  fs_initcall(ipv4_offload_init);
  
  static struct packet_type ip_packet_type __read_mostly = {
  	.type = cpu_to_be16(ETH_P_IP),
  	.func = ip_rcv,
  };

  static int __init inet_init(void)
  {

  	struct inet_protosw *q;
  	struct list_head *r;
  	int rc = -EINVAL;

  	sock_skb_cb_check_size(sizeof(struct inet_skb_parm));

  
  	rc = proto_register(&tcp_prot, 1);
  	if (rc)

  		goto out;

  
  	rc = proto_register(&udp_prot, 1);
  	if (rc)
  		goto out_unregister_tcp_proto;
  
  	rc = proto_register(&raw_prot, 1);
  	if (rc)
  		goto out_unregister_udp_proto;

  	rc = proto_register(&ping_prot, 1);
  	if (rc)
  		goto out_unregister_raw_proto;

  	/*

  	 *	Tell SOCKET that we are alive...

  	 */

  	(void)sock_register(&inet_family_ops);

  #ifdef CONFIG_SYSCTL
  	ip_static_sysctl_init();
  #endif

  	/*
  	 *	Add all the base protocols.
  	 */
  
  	if (inet_add_protocol(&icmp_protocol, IPPROTO_ICMP) < 0)

  		pr_crit("%s: Cannot add ICMP protocol
  ", __func__);

  	if (inet_add_protocol(&udp_protocol, IPPROTO_UDP) < 0)

  		pr_crit("%s: Cannot add UDP protocol
  ", __func__);