/*
   *	common UDP/RAW code
   *	Linux INET implementation
   *
   * Authors:
   * 	Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
   *
   * 	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.
   */

  #include <linux/types.h>
  #include <linux/module.h>
  #include <linux/ip.h>
  #include <linux/in.h>

  #include <net/ip.h>

  #include <net/sock.h>

  #include <net/route.h>

  #include <net/tcp_states.h>

  int __ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)

  {
  	struct inet_sock *inet = inet_sk(sk);
  	struct sockaddr_in *usin = (struct sockaddr_in *) uaddr;

  	struct flowi4 *fl4;

  	struct rtable *rt;

  	__be32 saddr;

  	int oif;
  	int err;

  	if (addr_len < sizeof(*usin))
  		return -EINVAL;
  
  	if (usin->sin_family != AF_INET)
  		return -EAFNOSUPPORT;

  
  	sk_dst_reset(sk);
  
  	oif = sk->sk_bound_dev_if;

  	saddr = inet->inet_saddr;

  	if (ipv4_is_multicast(usin->sin_addr.s_addr)) {

  		if (!oif)
  			oif = inet->mc_index;
  		if (!saddr)
  			saddr = inet->mc_addr;
  	}

  	fl4 = &inet->cork.fl.u.ip4;
  	rt = ip_route_connect(fl4, usin->sin_addr.s_addr, saddr,

  			      RT_CONN_FLAGS(sk), oif,
  			      sk->sk_protocol,

  			      inet->inet_sport, usin->sin_port, sk);

  	if (IS_ERR(rt)) {
  		err = PTR_ERR(rt);

  		if (err == -ENETUNREACH)

  			IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTNOROUTES);

  		goto out;

  	}

  	if ((rt->rt_flags & RTCF_BROADCAST) && !sock_flag(sk, SOCK_BROADCAST)) {
  		ip_rt_put(rt);

  		err = -EACCES;
  		goto out;

  	}

  	if (!inet->inet_saddr)

  		inet->inet_saddr = fl4->saddr;	/* Update source address */

  	if (!inet->inet_rcv_saddr) {

  		inet->inet_rcv_saddr = fl4->saddr;

  		if (sk->sk_prot->rehash)
  			sk->sk_prot->rehash(sk);
  	}

  	inet->inet_daddr = fl4->daddr;

  	inet->inet_dport = usin->sin_port;

  	sk->sk_state = TCP_ESTABLISHED;

  	sk_set_txhash(sk);

  	inet->inet_id = jiffies;

  	sk_dst_set(sk, &rt->dst);

  	err = 0;
  out:

  	return err;

  }

  EXPORT_SYMBOL(__ip4_datagram_connect);
  
  int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
  {
  	int res;
  
  	lock_sock(sk);
  	res = __ip4_datagram_connect(sk, uaddr, addr_len);
  	release_sock(sk);
  	return res;
  }

  EXPORT_SYMBOL(ip4_datagram_connect);

  /* Because UDP xmit path can manipulate sk_dst_cache without holding
   * socket lock, we need to use sk_dst_set() here,
   * even if we own the socket lock.
   */

  void ip4_datagram_release_cb(struct sock *sk)
  {
  	const struct inet_sock *inet = inet_sk(sk);
  	const struct ip_options_rcu *inet_opt;
  	__be32 daddr = inet->inet_daddr;

  	struct dst_entry *dst;

  	struct flowi4 fl4;
  	struct rtable *rt;

  	rcu_read_lock();

  
  	dst = __sk_dst_get(sk);
  	if (!dst || !dst->obsolete || dst->ops->check(dst, 0)) {
  		rcu_read_unlock();
  		return;
  	}

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

  
  	dst = !IS_ERR(rt) ? &rt->dst : NULL;
  	sk_dst_set(sk, dst);

  	rcu_read_unlock();
  }
  EXPORT_SYMBOL_GPL(ip4_datagram_release_cb);