include/net/inet_ecn.h

   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
  10 enum {
  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
  18 static inline int INET_ECN_is_ce(__u8 dsfield)
  19 {
  20         return (dsfield & INET_ECN_MASK) == INET_ECN_CE;
  21 }
  22
  23 static inline int INET_ECN_is_not_ect(__u8 dsfield)
  24 {
  25         return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT;
  26 }
  27
  28 static 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  */
  41 static 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
  49 static 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
  56 static 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
  72 static 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
  99 static inline void IP_ECN_clear(struct iphdr *iph)
 100 {
 101         iph->tos &= ~INET_ECN_MASK;
 102 }
 103
 104 static 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
 110 struct ipv6hdr;
 111
 112 static 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
 120 static inline void IP6_ECN_clear(struct ipv6hdr *iph)
 121 {
 122         *(__be32*)iph &= ~htonl(INET_ECN_MASK << 20);
 123 }
 124
 125 static 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
 131 static 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