/*
   * 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.
   *
   *             Support for INET6 connection oriented protocols.
   *
   * Authors:    See the TCPv6 sources
   *
   *             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/module.h>
  #include <linux/in6.h>
  #include <linux/ipv6.h>
  #include <linux/jhash.h>

  #include <linux/slab.h>

  
  #include <net/addrconf.h>
  #include <net/inet_connection_sock.h>

  #include <net/inet_ecn.h>
  #include <net/inet_hashtables.h>
  #include <net/ip6_route.h>

  #include <net/sock.h>

  #include <net/inet6_connection_sock.h>

  #include <net/sock_reuseport.h>

  struct dst_entry *inet6_csk_route_req(const struct sock *sk,

  				      struct flowi6 *fl6,

  				      const struct request_sock *req,
  				      u8 proto)

  {

  	struct inet_request_sock *ireq = inet_rsk(req);

  	const struct ipv6_pinfo *np = inet6_sk(sk);

  	struct in6_addr *final_p, final;
  	struct dst_entry *dst;

  	memset(fl6, 0, sizeof(*fl6));

  	fl6->flowi6_proto = proto;

  	fl6->daddr = ireq->ir_v6_rmt_addr;

  	rcu_read_lock();
  	final_p = fl6_update_dst(fl6, rcu_dereference(np->opt), &final);
  	rcu_read_unlock();

  	fl6->saddr = ireq->ir_v6_loc_addr;
  	fl6->flowi6_oif = ireq->ir_iif;

  	fl6->flowi6_mark = ireq->ir_mark;

  	fl6->fl6_dport = ireq->ir_rmt_port;

  	fl6->fl6_sport = htons(ireq->ir_num);

  	fl6->flowi6_uid = sk->sk_uid;

  	security_req_classify_flow(req, flowi6_to_flowi(fl6));

  	dst = ip6_dst_lookup_flow(sk, fl6, final_p);

  	if (IS_ERR(dst))

  		return NULL;
  
  	return dst;
  }

  EXPORT_SYMBOL(inet6_csk_route_req);

  void inet6_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)

  {

  	struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) uaddr;
  
  	sin6->sin6_family = AF_INET6;

  	sin6->sin6_addr = sk->sk_v6_daddr;

  	sin6->sin6_port	= inet_sk(sk)->inet_dport;

  	/* We do not store received flowlabel for TCP */
  	sin6->sin6_flowinfo = 0;

  	sin6->sin6_scope_id = ipv6_iface_scope_id(&sin6->sin6_addr,
  						  sk->sk_bound_dev_if);

  }

  EXPORT_SYMBOL_GPL(inet6_csk_addr2sockaddr);

  static inline

  struct dst_entry *__inet6_csk_dst_check(struct sock *sk, u32 cookie)
  {

  	return __sk_dst_check(sk, cookie);

  }

  static struct dst_entry *inet6_csk_route_socket(struct sock *sk,
  						struct flowi6 *fl6)

  {

  	struct inet_sock *inet = inet_sk(sk);
  	struct ipv6_pinfo *np = inet6_sk(sk);

  	struct in6_addr *final_p, final;

  	struct dst_entry *dst;

  	memset(fl6, 0, sizeof(*fl6));
  	fl6->flowi6_proto = sk->sk_protocol;

  	fl6->daddr = sk->sk_v6_daddr;

  	fl6->saddr = np->saddr;
  	fl6->flowlabel = np->flow_label;
  	IP6_ECN_flow_xmit(sk, fl6->flowlabel);
  	fl6->flowi6_oif = sk->sk_bound_dev_if;
  	fl6->flowi6_mark = sk->sk_mark;
  	fl6->fl6_sport = inet->inet_sport;
  	fl6->fl6_dport = inet->inet_dport;

  	fl6->flowi6_uid = sk->sk_uid;

  	security_sk_classify_flow(sk, flowi6_to_flowi(fl6));

  	rcu_read_lock();
  	final_p = fl6_update_dst(fl6, rcu_dereference(np->opt), &final);
  	rcu_read_unlock();

  	dst = __inet6_csk_dst_check(sk, np->dst_cookie);

  	if (!dst) {

  		dst = ip6_dst_lookup_flow(sk, fl6, final_p);

  		if (!IS_ERR(dst))

  			ip6_dst_store(sk, dst, NULL, NULL);

  	}
  	return dst;
  }

  int inet6_csk_xmit(struct sock *sk, struct sk_buff *skb, struct flowi *fl_unused)

  {

  	struct ipv6_pinfo *np = inet6_sk(sk);
  	struct flowi6 fl6;
  	struct dst_entry *dst;
  	int res;

  	dst = inet6_csk_route_socket(sk, &fl6);

  	if (IS_ERR(dst)) {
  		sk->sk_err_soft = -PTR_ERR(dst);
  		sk->sk_route_caps = 0;
  		kfree_skb(skb);
  		return PTR_ERR(dst);

  	}

  	rcu_read_lock();
  	skb_dst_set_noref(skb, dst);

  
  	/* Restore final destination back after routing done */

  	fl6.daddr = sk->sk_v6_daddr;

  	res = ip6_xmit(sk, skb, &fl6, sk->sk_mark, rcu_dereference(np->opt),

  		       np->tclass);

  	rcu_read_unlock();
  	return res;

  }

  EXPORT_SYMBOL_GPL(inet6_csk_xmit);

  
  struct dst_entry *inet6_csk_update_pmtu(struct sock *sk, u32 mtu)
  {

  	struct flowi6 fl6;
  	struct dst_entry *dst = inet6_csk_route_socket(sk, &fl6);

  
  	if (IS_ERR(dst))
  		return NULL;

  	dst->ops->update_pmtu(dst, sk, NULL, mtu);

  	dst = inet6_csk_route_socket(sk, &fl6);
  	return IS_ERR(dst) ? NULL : dst;

  }
  EXPORT_SYMBOL_GPL(inet6_csk_update_pmtu);