text: #ifndef _NET_TCP_ECN_H_
  #define _NET_TCP_ECN_H_ 1
  
  #include <net/inet_ecn.h>
  
  #define TCP_HP_BITS (~(TCP_RESERVED_BITS|TCP_FLAG_PSH))
  
  #define	TCP_ECN_OK		1
  #define TCP_ECN_QUEUE_CWR	2
  #define TCP_ECN_DEMAND_CWR	4
  
  static __inline__ void
  TCP_ECN_queue_cwr(struct tcp_opt *tp)
  {
  	if (tp->ecn_flags&TCP_ECN_OK)
  		tp->ecn_flags |= TCP_ECN_QUEUE_CWR;
  }
  
  
  /* Output functions */
  
  static __inline__ void
  TCP_ECN_send_synack(struct tcp_opt *tp, struct sk_buff *skb)
  {
  	TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_CWR;
  	if (!(tp->ecn_flags&TCP_ECN_OK))
  		TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_ECE;
  }
  
  static __inline__ void
  TCP_ECN_send_syn(struct sock *sk, struct tcp_opt *tp, struct sk_buff *skb)
  {
  	tp->ecn_flags = 0;
  	if (sysctl_tcp_ecn && !(sk->sk_route_caps & NETIF_F_TSO)) {
  		TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_ECE|TCPCB_FLAG_CWR;
  		tp->ecn_flags = TCP_ECN_OK;
  		sk->sk_no_largesend = 1;
  	}
  }
  
  static __inline__ void
  TCP_ECN_make_synack(struct open_request *req, struct tcphdr *th)
  {
  	if (req->ecn_ok)
  		th->ece = 1;
  }
  
  static __inline__ void
  TCP_ECN_send(struct sock *sk, struct tcp_opt *tp, struct sk_buff *skb, int tcp_header_len)
  {
  	if (tp->ecn_flags & TCP_ECN_OK) {
  		/* Not-retransmitted data segment: set ECT and inject CWR. */
  		if (skb->len != tcp_header_len &&
  		    !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) {
  			INET_ECN_xmit(sk);
  			if (tp->ecn_flags&TCP_ECN_QUEUE_CWR) {
  				tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR;
  				skb->h.th->cwr = 1;
  			}
  		} else {
  			/* ACK or retransmitted segment: clear ECT|CE */
  			INET_ECN_dontxmit(sk);
  		}
  		if (tp->ecn_flags & TCP_ECN_DEMAND_CWR)
  			skb->h.th->ece = 1;
  	}
  }
  
  /* Input functions */
  
  static __inline__ void
  TCP_ECN_accept_cwr(struct tcp_opt *tp, struct sk_buff *skb)
  {
  	if (skb->h.th->cwr)
  		tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
  }
  
  static __inline__ void
  TCP_ECN_withdraw_cwr(struct tcp_opt *tp)
  {
  	tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
  }
  
  static __inline__ void
  TCP_ECN_check_ce(struct tcp_opt *tp, struct sk_buff *skb)
  {
  	if (tp->ecn_flags&TCP_ECN_OK) {
  		if (INET_ECN_is_ce(TCP_SKB_CB(skb)->flags))
  			tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
  		/* Funny extension: if ECT is not set on a segment,
  		 * it is surely retransmit. It is not in ECN RFC,
  		 * but Linux follows this rule. */
  		else if (!INET_ECN_is_capable((TCP_SKB_CB(skb)->flags)))
  			tcp_enter_quickack_mode(tp);
  	}
  }
  
  static __inline__ void
  TCP_ECN_rcv_synack(struct tcp_opt *tp, struct tcphdr *th)
  {
  	if ((tp->ecn_flags&TCP_ECN_OK) && (!th->ece || th->cwr))
  		tp->ecn_flags &= ~TCP_ECN_OK;
  }
  
  static __inline__ void
  TCP_ECN_rcv_syn(struct tcp_opt *tp, struct tcphdr *th)
  {
  	if ((tp->ecn_flags&TCP_ECN_OK) && (!th->ece || !th->cwr))
  		tp->ecn_flags &= ~TCP_ECN_OK;
  }
  
  static __inline__ int
  TCP_ECN_rcv_ecn_echo(struct tcp_opt *tp, struct tcphdr *th)
  {
  	if (th->ece && !th->syn && (tp->ecn_flags&TCP_ECN_OK))
  		return 1;
  	return 0;
  }
  
  static __inline__ void
  TCP_ECN_openreq_child(struct tcp_opt *tp, struct open_request *req)
  {
  	tp->ecn_flags = req->ecn_ok ? TCP_ECN_OK : 0;
  }
  
  static __inline__ void
  TCP_ECN_create_request(struct open_request *req, struct tcphdr *th)
  {
  	if (sysctl_tcp_ecn && th->ece && th->cwr)
  		req->ecn_ok = 1;
  }
  
  #endif
  