#ifndef _INET_ECN_H_
  #define _INET_ECN_H_
  
  #include <linux/ip.h>

  #include <linux/skbuff.h>

  
  #include <net/inet_sock.h>

  #include <net/dsfield.h>
  
  enum {
  	INET_ECN_NOT_ECT = 0,
  	INET_ECN_ECT_1 = 1,
  	INET_ECN_ECT_0 = 2,
  	INET_ECN_CE = 3,
  	INET_ECN_MASK = 3,
  };

  extern int sysctl_tunnel_ecn_log;

  static inline int INET_ECN_is_ce(__u8 dsfield)
  {
  	return (dsfield & INET_ECN_MASK) == INET_ECN_CE;
  }
  
  static inline int INET_ECN_is_not_ect(__u8 dsfield)
  {
  	return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT;
  }
  
  static inline int INET_ECN_is_capable(__u8 dsfield)
  {

  	return dsfield & INET_ECN_ECT_0;

  }

  /*
   * RFC 3168 9.1.1
   *  The full-functionality option for ECN encapsulation is to copy the
   *  ECN codepoint of the inside header to the outside header on
   *  encapsulation if the inside header is not-ECT or ECT, and to set the
   *  ECN codepoint of the outside header to ECT(0) if the ECN codepoint of
   *  the inside header is CE.
   */

  static inline __u8 INET_ECN_encapsulate(__u8 outer, __u8 inner)
  {
  	outer &= ~INET_ECN_MASK;
  	outer |= !INET_ECN_is_ce(inner) ? (inner & INET_ECN_MASK) :
  					  INET_ECN_ECT_0;
  	return outer;
  }

  static inline void INET_ECN_xmit(struct sock *sk)
  {
  	inet_sk(sk)->tos |= INET_ECN_ECT_0;
  	if (inet6_sk(sk) != NULL)
  		inet6_sk(sk)->tclass |= INET_ECN_ECT_0;
  }
  
  static inline void INET_ECN_dontxmit(struct sock *sk)
  {
  	inet_sk(sk)->tos &= ~INET_ECN_MASK;
  	if (inet6_sk(sk) != NULL)
  		inet6_sk(sk)->tclass &= ~INET_ECN_MASK;
  }

  
  #define IP6_ECN_flow_init(label) do {		\
        (label) &= ~htonl(INET_ECN_MASK << 20);	\
      } while (0)
  
  #define	IP6_ECN_flow_xmit(sk, label) do {				\

  	if (INET_ECN_is_capable(inet6_sk(sk)->tclass))			\

  		(label) |= htonl(INET_ECN_ECT_0 << 20);			\

      } while (0)

  static inline int IP_ECN_set_ce(struct iphdr *iph)

  {

  	u32 check = (__force u32)iph->check;

  	u32 ecn = (iph->tos + 1) & INET_ECN_MASK;
  
  	/*
  	 * After the last operation we have (in binary):
  	 * INET_ECN_NOT_ECT => 01
  	 * INET_ECN_ECT_1   => 10
  	 * INET_ECN_ECT_0   => 11
  	 * INET_ECN_CE      => 00
  	 */
  	if (!(ecn & 2))

  		return !ecn;

  
  	/*
  	 * The following gives us:
  	 * INET_ECN_ECT_1 => check += htons(0xFFFD)
  	 * INET_ECN_ECT_0 => check += htons(0xFFFE)
  	 */

  	check += (__force u16)htons(0xFFFB) + (__force u16)htons(ecn);

  	iph->check = (__force __sum16)(check + (check>=0xFFFF));

  	iph->tos |= INET_ECN_CE;

  	return 1;

  }
  
  static inline void IP_ECN_clear(struct iphdr *iph)
  {
  	iph->tos &= ~INET_ECN_MASK;
  }

  static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner)

  {

  	dscp &= ~INET_ECN_MASK;

  	ipv4_change_dsfield(inner, INET_ECN_MASK, dscp);
  }
  
  struct ipv6hdr;

  /* Note:
   * IP_ECN_set_ce() has to tweak IPV4 checksum when setting CE,
   * meaning both changes have no effect on skb->csum if/when CHECKSUM_COMPLETE
   * In IPv6 case, no checksum compensates the change in IPv6 header,
   * so we have to update skb->csum.
   */
  static inline int IP6_ECN_set_ce(struct sk_buff *skb, struct ipv6hdr *iph)

  {

  	__be32 from, to;

  	if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph)))

  		return 0;

  
  	from = *(__be32 *)iph;
  	to = from | htonl(INET_ECN_CE << 20);
  	*(__be32 *)iph = to;
  	if (skb->ip_summed == CHECKSUM_COMPLETE)

  		skb->csum = csum_add(csum_sub(skb->csum, (__force __wsum)from),
  				     (__force __wsum)to);

  	return 1;

  }
  
  static inline void IP6_ECN_clear(struct ipv6hdr *iph)
  {

  	*(__be32*)iph &= ~htonl(INET_ECN_MASK << 20);

  }

  static inline void ipv6_copy_dscp(unsigned int dscp, struct ipv6hdr *inner)

  {

  	dscp &= ~INET_ECN_MASK;

  	ipv6_change_dsfield(inner, INET_ECN_MASK, dscp);
  }

  static inline int INET_ECN_set_ce(struct sk_buff *skb)
  {
  	switch (skb->protocol) {

  	case cpu_to_be16(ETH_P_IP):

  		if (skb_network_header(skb) + sizeof(struct iphdr) <=
  		    skb_tail_pointer(skb))

  			return IP_ECN_set_ce(ip_hdr(skb));

  		break;

  	case cpu_to_be16(ETH_P_IPV6):

  		if (skb_network_header(skb) + sizeof(struct ipv6hdr) <=
  		    skb_tail_pointer(skb))

  			return IP6_ECN_set_ce(skb, ipv6_hdr(skb));

  		break;
  	}
  
  	return 0;
  }

  /*

   * RFC 6040 4.2

   *  To decapsulate the inner header at the tunnel egress, a compliant
   *  tunnel egress MUST set the outgoing ECN field to the codepoint at the
   *  intersection of the appropriate arriving inner header (row) and outer
   *  header (column) in Figure 4
   *
   *      +---------+------------------------------------------------+
   *      |Arriving |            Arriving Outer Header               |
   *      |   Inner +---------+------------+------------+------------+
   *      |  Header | Not-ECT | ECT(0)     | ECT(1)     |     CE     |
   *      +---------+---------+------------+------------+------------+
   *      | Not-ECT | Not-ECT |Not-ECT(!!!)|Not-ECT(!!!)| <drop>(!!!)|
   *      |  ECT(0) |  ECT(0) | ECT(0)     | ECT(1)     |     CE     |
   *      |  ECT(1) |  ECT(1) | ECT(1) (!) | ECT(1)     |     CE     |
   *      |    CE   |      CE |     CE     |     CE(!!!)|     CE     |
   *      +---------+---------+------------+------------+------------+
   *
   *             Figure 4: New IP in IP Decapsulation Behaviour
   *
   *  returns 0 on success
   *          1 if something is broken and should be logged (!!! above)
   *          2 if packet should be dropped
   */
  static inline int INET_ECN_decapsulate(struct sk_buff *skb,
  				       __u8 outer, __u8 inner)
  {
  	if (INET_ECN_is_not_ect(inner)) {
  		switch (outer & INET_ECN_MASK) {
  		case INET_ECN_NOT_ECT:
  			return 0;
  		case INET_ECN_ECT_0:
  		case INET_ECN_ECT_1:
  			return 1;
  		case INET_ECN_CE:
  			return 2;
  		}
  	}
  
  	if (INET_ECN_is_ce(outer))
  		INET_ECN_set_ce(skb);
  
  	return 0;
  }
  
  static inline int IP_ECN_decapsulate(const struct iphdr *oiph,
  				     struct sk_buff *skb)
  {
  	__u8 inner;
  
  	if (skb->protocol == htons(ETH_P_IP))
  		inner = ip_hdr(skb)->tos;
  	else if (skb->protocol == htons(ETH_P_IPV6))
  		inner = ipv6_get_dsfield(ipv6_hdr(skb));
  	else
  		return 0;
  
  	return INET_ECN_decapsulate(skb, oiph->tos, inner);
  }
  
  static inline int IP6_ECN_decapsulate(const struct ipv6hdr *oipv6h,
  				      struct sk_buff *skb)
  {
  	__u8 inner;
  
  	if (skb->protocol == htons(ETH_P_IP))
  		inner = ip_hdr(skb)->tos;
  	else if (skb->protocol == htons(ETH_P_IPV6))
  		inner = ipv6_get_dsfield(ipv6_hdr(skb));
  	else
  		return 0;
  
  	return INET_ECN_decapsulate(skb, ipv6_get_dsfield(oipv6h), inner);
  }

  #endif