1#ifndef _NET_TCP_ECN_H_
2#define _NET_TCP_ECN_H_ 1
3
4#include <net/inet_ecn.h>
5
6#define TCP_HP_BITS (~(TCP_RESERVED_BITS|TCP_FLAG_PSH))
7
8#define	TCP_ECN_OK		1
9#define TCP_ECN_QUEUE_CWR	2
10#define TCP_ECN_DEMAND_CWR	4
11
12static __inline__ void
13TCP_ECN_queue_cwr(struct tcp_opt *tp)
14{
15	if (tp->ecn_flags&TCP_ECN_OK)
16		tp->ecn_flags |= TCP_ECN_QUEUE_CWR;
17}
18
19
20/* Output functions */
21
22static __inline__ void
23TCP_ECN_send_synack(struct tcp_opt *tp, struct sk_buff *skb)
24{
25	TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_CWR;
26	if (!(tp->ecn_flags&TCP_ECN_OK))
27		TCP_SKB_CB(skb)->flags &= ~TCPCB_FLAG_ECE;
28}
29
30static __inline__ void
31TCP_ECN_send_syn(struct tcp_opt *tp, struct sk_buff *skb)
32{
33	tp->ecn_flags = 0;
34	if (sysctl_tcp_ecn) {
35		TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_ECE|TCPCB_FLAG_CWR;
36		tp->ecn_flags = TCP_ECN_OK;
37	}
38}
39
40static __inline__ void
41TCP_ECN_make_synack(struct open_request *req, struct tcphdr *th)
42{
43	if (req->ecn_ok)
44		th->ece = 1;
45}
46
47static __inline__ void
48TCP_ECN_send(struct sock *sk, struct tcp_opt *tp, struct sk_buff *skb, int tcp_header_len)
49{
50	if (tp->ecn_flags & TCP_ECN_OK) {
51		/* Not-retransmitted data segment: set ECT and inject CWR. */
52		if (skb->len != tcp_header_len &&
53		    !before(TCP_SKB_CB(skb)->seq, tp->snd_nxt)) {
54			INET_ECN_xmit(sk);
55			if (tp->ecn_flags&TCP_ECN_QUEUE_CWR) {
56				tp->ecn_flags &= ~TCP_ECN_QUEUE_CWR;
57				skb->h.th->cwr = 1;
58			}
59		} else {
60			/* ACK or retransmitted segment: clear ECT|CE */
61			INET_ECN_dontxmit(sk);
62		}
63		if (tp->ecn_flags & TCP_ECN_DEMAND_CWR)
64			skb->h.th->ece = 1;
65	}
66}
67
68/* Input functions */
69
70static __inline__ void
71TCP_ECN_accept_cwr(struct tcp_opt *tp, struct sk_buff *skb)
72{
73	if (skb->h.th->cwr)
74		tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
75}
76
77static __inline__ void
78TCP_ECN_withdraw_cwr(struct tcp_opt *tp)
79{
80	tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
81}
82
83static __inline__ void
84TCP_ECN_check_ce(struct tcp_opt *tp, struct sk_buff *skb)
85{
86	if (tp->ecn_flags&TCP_ECN_OK) {
87		if (INET_ECN_is_ce(TCP_SKB_CB(skb)->flags))
88			tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
89		/* Funny extension: if ECT is not set on a segment,
90		 * it is surely retransmit. It is not in ECN RFC,
91		 * but Linux follows this rule. */
92		else if (!INET_ECN_is_capable((TCP_SKB_CB(skb)->flags)))
93			tcp_enter_quickack_mode(tp);
94	}
95}
96
97static __inline__ void
98TCP_ECN_rcv_synack(struct tcp_opt *tp, struct tcphdr *th)
99{
100	if ((tp->ecn_flags&TCP_ECN_OK) && (!th->ece || th->cwr))
101		tp->ecn_flags &= ~TCP_ECN_OK;
102}
103
104static __inline__ void
105TCP_ECN_rcv_syn(struct tcp_opt *tp, struct tcphdr *th)
106{
107	if ((tp->ecn_flags&TCP_ECN_OK) && (!th->ece || !th->cwr))
108		tp->ecn_flags &= ~TCP_ECN_OK;
109}
110
111static __inline__ int
112TCP_ECN_rcv_ecn_echo(struct tcp_opt *tp, struct tcphdr *th)
113{
114	if (th->ece && !th->syn && (tp->ecn_flags&TCP_ECN_OK))
115		return 1;
116	return 0;
117}
118
119static __inline__ void
120TCP_ECN_openreq_child(struct tcp_opt *tp, struct open_request *req)
121{
122	tp->ecn_flags = req->ecn_ok ? TCP_ECN_OK : 0;
123}
124
125static __inline__ void
126TCP_ECN_create_request(struct open_request *req, struct tcphdr *th)
127{
128	if (sysctl_tcp_ecn && th->ece && th->cwr)
129		req->ecn_ok = 1;
130}
131
132#endif
133