#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/ipv6.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv6.h>
#include <net/dst.h>
#include <net/ipv6.h>
#include <net/ip6_route.h>
#include <net/xfrm.h>
#include <net/ip6_checksum.h>
#include <net/netfilter/nf_queue.h>

int ip6_route_me_harder(struct sk_buff *skb)
{
        struct net *net = dev_net(skb_dst(skb)->dev);
        struct ipv6hdr *iph = ipv6_hdr(skb);
        struct dst_entry *dst;
        struct flowi fl = {
                .oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
                .mark = skb->mark,
                .nl_u =
                { .ip6_u =
                  { .daddr = iph->daddr,
                    .saddr = iph->saddr, } },
        };

        dst = ip6_route_output(net, skb->sk, &fl);

#ifdef CONFIG_XFRM
        if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
            xfrm_decode_session(skb, &fl, AF_INET6) == 0) {
                struct dst_entry *dst2 = skb_dst(skb);

                if (xfrm_lookup(net, &dst2, &fl, skb->sk, 0)) {
                        skb_dst_set(skb, NULL);
                        return -1;
                }
                skb_dst_set(skb, dst2);
        }
#endif

        if (dst->error) {
                IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
                LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
                dst_release(dst);
                return -EINVAL;
        }

        /* Drop old route. */
        skb_dst_drop(skb);

        skb_dst_set(skb, dst);
        return 0;
}
EXPORT_SYMBOL(ip6_route_me_harder);

/*
 * Extra routing may needed on local out, as the QUEUE target never
 * returns control to the table.
 */

struct ip6_rt_info {
        struct in6_addr daddr;
        struct in6_addr saddr;
        u_int32_t mark;
};

static void nf_ip6_saveroute(const struct sk_buff *skb,
                             struct nf_queue_entry *entry)
{
        struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);

        if (entry->hook == NF_INET_LOCAL_OUT) {
                struct ipv6hdr *iph = ipv6_hdr(skb);

                rt_info->daddr = iph->daddr;
                rt_info->saddr = iph->saddr;
                rt_info->mark = skb->mark;
        }
}

static int nf_ip6_reroute(struct sk_buff *skb,
                          const struct nf_queue_entry *entry)
{
        struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);

        if (entry->hook == NF_INET_LOCAL_OUT) {
                struct ipv6hdr *iph = ipv6_hdr(skb);
                if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
                    !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
                    skb->mark != rt_info->mark)
                        return ip6_route_me_harder(skb);
        }
        return 0;
}

static int nf_ip6_route(struct dst_entry **dst, struct flowi *fl)
{
        *dst = ip6_route_output(&init_net, NULL, fl);
        return (*dst)->error;
}

__sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
                             unsigned int dataoff, u_int8_t protocol)
{
        struct ipv6hdr *ip6h = ipv6_hdr(skb);
        __sum16 csum = 0;

        switch (skb->ip_summed) {
        case CHECKSUM_COMPLETE:
                if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
                        break;
                if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
                                     skb->len - dataoff, protocol,
                                     csum_sub(skb->csum,
                                              skb_checksum(skb, 0,
                                                           dataoff, 0)))) {
                        skb->ip_summed = CHECKSUM_UNNECESSARY;
                        break;
                }
                /* fall through */
        case CHECKSUM_NONE:
                skb->csum = ~csum_unfold(
                                csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
                                             skb->len - dataoff,
                                             protocol,
                                             csum_sub(0,
                                                      skb_checksum(skb, 0,
                                                                   dataoff, 0))));
                csum = __skb_checksum_complete(skb);
        }
        return csum;
}
EXPORT_SYMBOL(nf_ip6_checksum);

static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
                                       unsigned int dataoff, unsigned int len,
                                       u_int8_t protocol)
{
        struct ipv6hdr *ip6h = ipv6_hdr(skb);
        __wsum hsum;
        __sum16 csum = 0;

        switch (skb->ip_summed) {
        case CHECKSUM_COMPLETE:
                if (len == skb->len - dataoff)
                        return nf_ip6_checksum(skb, hook, dataoff, protocol);
                /* fall through */
        case CHECKSUM_NONE:
                hsum = skb_checksum(skb, 0, dataoff, 0);
                skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
                                                         &ip6h->daddr,
                                                         skb->len - dataoff,
                                                         protocol,
                                                         csum_sub(0, hsum)));
                skb->ip_summed = CHECKSUM_NONE;
                csum = __skb_checksum_complete_head(skb, dataoff + len);
                if (!csum)
                        skb->ip_summed = CHECKSUM_UNNECESSARY;
        }
        return csum;
};

static const struct nf_afinfo nf_ip6_afinfo = {
        .family                 = AF_INET6,
        .checksum               = nf_ip6_checksum,
        .checksum_partial       = nf_ip6_checksum_partial,
        .route                  = nf_ip6_route,
        .saveroute              = nf_ip6_saveroute,
        .reroute                = nf_ip6_reroute,
        .route_key_size         = sizeof(struct ip6_rt_info),
};

int __init ipv6_netfilter_init(void)
{
        return nf_register_afinfo(&nf_ip6_afinfo);
}

/* This can be called from inet6_init() on errors, so it cannot
 * be marked __exit. -DaveM
 */
void ipv6_netfilter_fini(void)
{
        nf_unregister_afinfo(&nf_ip6_afinfo);
}