linux/include/net/inet_ecn.h
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   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
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