root/include/net/inet_ecn.h

INCLUDED FROM

DEFINITIONS

1. INET_ECN_is_ce
2. INET_ECN_is_not_ect
3. INET_ECN_is_capable
4. INET_ECN_encapsulate
5. IP_ECN_set_ce
6. IP_ECN_clear
7. ipv4_copy_dscp
8. IP6_ECN_set_ce
9. IP6_ECN_clear
10. ipv6_copy_dscp
11. INET_ECN_set_ce

#ifndef _INET_ECN_H_
#define _INET_ECN_H_

#include <linux/ip.h>
#include <linux/skbuff.h>

#include <net/inet_sock.h>
#include <net/dsfield.h>

enum {
        INET_ECN_NOT_ECT = 0,
        INET_ECN_ECT_1 = 1,
        INET_ECN_ECT_0 = 2,
        INET_ECN_CE = 3,
        INET_ECN_MASK = 3,
};

static inline int INET_ECN_is_ce(__u8 dsfield)
{
        return (dsfield & INET_ECN_MASK) == INET_ECN_CE;
}

static inline int INET_ECN_is_not_ect(__u8 dsfield)
{
        return (dsfield & INET_ECN_MASK) == INET_ECN_NOT_ECT;
}

static inline int INET_ECN_is_capable(__u8 dsfield)
{
        return (dsfield & INET_ECN_ECT_0);
}

static inline __u8 INET_ECN_encapsulate(__u8 outer, __u8 inner)
{
        outer &= ~INET_ECN_MASK;
        outer |= !INET_ECN_is_ce(inner) ? (inner & INET_ECN_MASK) :
                                          INET_ECN_ECT_0;
        return outer;
}

#define INET_ECN_xmit(sk) do { inet_sk(sk)->tos |= INET_ECN_ECT_0; } while (0)
#define INET_ECN_dontxmit(sk) \
        do { inet_sk(sk)->tos &= ~INET_ECN_MASK; } while (0)

#define IP6_ECN_flow_init(label) do {           \
      (label) &= ~htonl(INET_ECN_MASK << 20);   \
    } while (0)

#define IP6_ECN_flow_xmit(sk, label) do {                               \
        if (INET_ECN_is_capable(inet6_sk(sk)->tclass))                  \
                (label) |= htonl(INET_ECN_ECT_0 << 20);                 \
    } while (0)

static inline int IP_ECN_set_ce(struct iphdr *iph)
{
        u32 check = (__force u32)iph->check;
        u32 ecn = (iph->tos + 1) & INET_ECN_MASK;

        /*
         * After the last operation we have (in binary):
         * INET_ECN_NOT_ECT => 01
         * INET_ECN_ECT_1   => 10
         * INET_ECN_ECT_0   => 11
         * INET_ECN_CE      => 00
         */
        if (!(ecn & 2))
                return !ecn;

        /*
         * The following gives us:
         * INET_ECN_ECT_1 => check += htons(0xFFFD)
         * INET_ECN_ECT_0 => check += htons(0xFFFE)
         */
        check += (__force u16)htons(0xFFFB) + (__force u16)htons(ecn);

        iph->check = (__force __sum16)(check + (check>=0xFFFF));
        iph->tos |= INET_ECN_CE;
        return 1;
}

static inline void IP_ECN_clear(struct iphdr *iph)
{
        iph->tos &= ~INET_ECN_MASK;
}

static inline void ipv4_copy_dscp(unsigned int dscp, struct iphdr *inner)
{
        dscp &= ~INET_ECN_MASK;
        ipv4_change_dsfield(inner, INET_ECN_MASK, dscp);
}

struct ipv6hdr;

static inline int IP6_ECN_set_ce(struct ipv6hdr *iph)
{
        if (INET_ECN_is_not_ect(ipv6_get_dsfield(iph)))
                return 0;
        *(__be32*)iph |= htonl(INET_ECN_CE << 20);
        return 1;
}

static inline void IP6_ECN_clear(struct ipv6hdr *iph)
{
        *(__be32*)iph &= ~htonl(INET_ECN_MASK << 20);
}

static inline void ipv6_copy_dscp(unsigned int dscp, struct ipv6hdr *inner)
{
        dscp &= ~INET_ECN_MASK;
        ipv6_change_dsfield(inner, INET_ECN_MASK, dscp);
}

static inline int INET_ECN_set_ce(struct sk_buff *skb)
{
        switch (skb->protocol) {
        case __constant_htons(ETH_P_IP):
                if (skb->network_header + sizeof(struct iphdr) <= skb->tail)
                        return IP_ECN_set_ce(ip_hdr(skb));
                break;

        case __constant_htons(ETH_P_IPV6):
                if (skb->network_header + sizeof(struct ipv6hdr) <= skb->tail)
                        return IP6_ECN_set_ce(ipv6_hdr(skb));
                break;
        }

        return 0;
}

#endif