1#ifndef _INET_ECN_H_
2#define _INET_ECN_H_
3
4#include <linux/ip.h>
5#include <linux/skbuff.h>
6
7#include <net/inet_sock.h>
8#include <net/dsfield.h>
9
10enum {
11	INET_ECN_NOT_ECT = 0,
12	INET_ECN_ECT_1 = 1,
13	INET_ECN_ECT_0 = 2,
14	INET_ECN_CE = 3,
15	INET_ECN_MASK = 3,
16};
17
18static inline int INET_ECN_is_ce(__u8 dsfield)
19{
20	return (dsfield & INET_ECN_MASK) == INET_ECN_CE;
21}
22
23static inline int INET_ECN_is_not_ect(__u8 dsfield)
24{
25	return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT;
26}
27
28static inline int INET_ECN_is_capable(__u8 dsfield)
29{
30	return (dsfield & INET_ECN_ECT_0);
31}
32
33static inline __u8 INET_ECN_encapsulate(__u8 outer, __u8 inner)
34{
35	outer &= ~INET_ECN_MASK;
36	outer |= !INET_ECN_is_ce(inner) ? (inner & INET_ECN_MASK) :
37					  INET_ECN_ECT_0;
38	return outer;
39}
40
41#define	INET_ECN_xmit(sk) do { inet_sk(sk)->tos |= INET_ECN_ECT_0; } while (0)
42#define	INET_ECN_dontxmit(sk) \
43	do { inet_sk(sk)->tos &= ~INET_ECN_MASK; } while (0)
44
45#define IP6_ECN_flow_init(label) do {		\
46      (label) &= ~htonl(INET_ECN_MASK << 20);	\
47    } while (0)
48
49#define	IP6_ECN_flow_xmit(sk, label) do {				\
50	if (INET_ECN_is_capable(inet_sk(sk)->tos))			\
51		(label) |= htonl(INET_ECN_ECT_0 << 20);			\
52    } while (0)
53
54static inline int IP_ECN_set_ce(struct iphdr *iph)
55{
56	u32 check = (__force u32)iph->check;
57	u32 ecn = (iph->tos + 1) & INET_ECN_MASK;
58
59	/*
60	 * After the last operation we have (in binary):
61	 * INET_ECN_NOT_ECT => 01
62	 * INET_ECN_ECT_1   => 10
63	 * INET_ECN_ECT_0   => 11
64	 * INET_ECN_CE      => 00
65	 */
66	if (!(ecn & 2))
67		return !ecn;
68
69	/*
70	 * The following gives us:
71	 * INET_ECN_ECT_1 => check += htons(0xFFFD)
72	 * INET_ECN_ECT_0 => check += htons(0xFFFE)
73	 */
74	check += (__force u16)htons(0xFFFB) + (__force u16)htons(ecn);
75
76	iph->check = (__force __sum16)(check + (check>=0xFFFF));
77	iph->tos |= INET_ECN_CE;
78	return 1;
79}
80
81static inline void IP_ECN_clear(struct iphdr *iph)
82{
83	iph->tos &= ~INET_ECN_MASK;
84}
85
86static inline void ipv4_copy_dscp(struct iphdr *outer, struct iphdr *inner)
87{
88	u32 dscp = ipv4_get_dsfield(outer) & ~INET_ECN_MASK;
89	ipv4_change_dsfield(inner, INET_ECN_MASK, dscp);
90}
91
92struct ipv6hdr;
93
94static inline int IP6_ECN_set_ce(struct ipv6hdr *iph)
95{
96	if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph)))
97		return 0;
98	*(__be32*)iph |= htonl(INET_ECN_CE << 20);
99	return 1;
100}
101
102static inline void IP6_ECN_clear(struct ipv6hdr *iph)
103{
104	*(__be32*)iph &= ~htonl(INET_ECN_MASK << 20);
105}
106
107static inline void ipv6_copy_dscp(struct ipv6hdr *outer, struct ipv6hdr *inner)
108{
109	u32 dscp = ipv6_get_dsfield(outer) & ~INET_ECN_MASK;
110	ipv6_change_dsfield(inner, INET_ECN_MASK, dscp);
111}
112
113static inline int INET_ECN_set_ce(struct sk_buff *skb)
114{
115	switch (skb->protocol) {
116	case __constant_htons(ETH_P_IP):
117		if (skb->network_header + sizeof(struct iphdr) <= skb->tail)
118			return IP_ECN_set_ce(ip_hdr(skb));
119		break;
120
121	case __constant_htons(ETH_P_IPV6):
122		if (skb->network_header + sizeof(struct ipv6hdr) <= skb->tail)
123			return IP6_ECN_set_ce(ipv6_hdr(skb));
124		break;
125	}
126
127	return 0;
128}
129
130#endif
131