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
33/*
34 * RFC 3168 9.1.1
35 *  The full-functionality option for ECN encapsulation is to copy the
36 *  ECN codepoint of the inside header to the outside header on
37 *  encapsulation if the inside header is not-ECT or ECT, and to set the
38 *  ECN codepoint of the outside header to ECT(0) if the ECN codepoint of
39 *  the inside header is CE.
40 */
41static inline __u8 INET_ECN_encapsulate(__u8 outer, __u8 inner)
42{
43	outer &= ~INET_ECN_MASK;
44	outer |= !INET_ECN_is_ce(inner) ? (inner & INET_ECN_MASK) :
45					  INET_ECN_ECT_0;
46	return outer;
47}
48
49static inline void INET_ECN_xmit(struct sock *sk)
50{
51	inet_sk(sk)->tos |= INET_ECN_ECT_0;
52	if (inet6_sk(sk) != NULL)
53		inet6_sk(sk)->tclass |= INET_ECN_ECT_0;
54}
55
56static inline void INET_ECN_dontxmit(struct sock *sk)
57{
58	inet_sk(sk)->tos &= ~INET_ECN_MASK;
59	if (inet6_sk(sk) != NULL)
60		inet6_sk(sk)->tclass &= ~INET_ECN_MASK;
61}
62
63#define IP6_ECN_flow_init(label) do {		\
64      (label) &= ~htonl(INET_ECN_MASK << 20);	\
65    } while (0)
66
67#define	IP6_ECN_flow_xmit(sk, label) do {				\
68	if (INET_ECN_is_capable(inet6_sk(sk)->tclass))			\
69		(label) |= htonl(INET_ECN_ECT_0 << 20);			\
70    } while (0)
71
72static inline int IP_ECN_set_ce(struct iphdr *iph)
73{
74	u32 check = (__force u32)iph->check;
75	u32 ecn = (iph->tos + 1) & INET_ECN_MASK;
76
77	/*
78	 * After the last operation we have (in binary):
79	 * INET_ECN_NOT_ECT => 01
80	 * INET_ECN_ECT_1   => 10
81	 * INET_ECN_ECT_0   => 11
82	 * INET_ECN_CE      => 00
83	 */
84	if (!(ecn & 2))
85		return !ecn;
86
87	/*
88	 * The following gives us:
89	 * INET_ECN_ECT_1 => check += htons(0xFFFD)
90	 * INET_ECN_ECT_0 => check += htons(0xFFFE)
91	 */
92	check += (__force u16)htons(0xFFFB) + (__force u16)htons(ecn);
93
94	iph->check = (__force __sum16)(check + (check>=0xFFFF));
95	iph->tos |= INET_ECN_CE;
96	return 1;
97}
98
99static inline void IP_ECN_clear(struct iphdr *iph)
100{
101	iph->tos &= ~INET_ECN_MASK;
102}
103
104static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner)
105{
106	dscp &= ~INET_ECN_MASK;
107	ipv4_change_dsfield(inner, INET_ECN_MASK, dscp);
108}
109
110struct ipv6hdr;
111
112static inline int IP6_ECN_set_ce(struct ipv6hdr *iph)
113{
114	if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph)))
115		return 0;
116	*(__be32*)iph |= htonl(INET_ECN_CE << 20);
117	return 1;
118}
119
120static inline void IP6_ECN_clear(struct ipv6hdr *iph)
121{
122	*(__be32*)iph &= ~htonl(INET_ECN_MASK << 20);
123}
124
125static inline void ipv6_copy_dscp(unsigned int dscp, struct ipv6hdr *inner)
126{
127	dscp &= ~INET_ECN_MASK;
128	ipv6_change_dsfield(inner, INET_ECN_MASK, dscp);
129}
130
131static inline int INET_ECN_set_ce(struct sk_buff *skb)
132{
133	switch (skb->protocol) {
134	case cpu_to_be16(ETH_P_IP):
135		if (skb->network_header + sizeof(struct iphdr) <= skb->tail)
136			return IP_ECN_set_ce(ip_hdr(skb));
137		break;
138
139	case cpu_to_be16(ETH_P_IPV6):
140		if (skb->network_header + sizeof(struct ipv6hdr) <= skb->tail)
141			return IP6_ECN_set_ce(ipv6_hdr(skb));
142		break;
143	}
144
145	return 0;
146}
147
148#endif
149