/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _IPV6_FRAG_H
#define _IPV6_FRAG_H
#include <linux/icmpv6.h>
#include <linux/kernel.h>
#include <net/addrconf.h>
#include <net/ipv6.h>
#include <net/inet_frag.h>

enum ip6_defrag_users {
        IP6_DEFRAG_LOCAL_DELIVER,
        IP6_DEFRAG_CONNTRACK_IN,
        __IP6_DEFRAG_CONNTRACK_IN       = IP6_DEFRAG_CONNTRACK_IN + USHRT_MAX,
        IP6_DEFRAG_CONNTRACK_OUT,
        __IP6_DEFRAG_CONNTRACK_OUT      = IP6_DEFRAG_CONNTRACK_OUT + USHRT_MAX,
        IP6_DEFRAG_CONNTRACK_BRIDGE_IN,
        __IP6_DEFRAG_CONNTRACK_BRIDGE_IN = IP6_DEFRAG_CONNTRACK_BRIDGE_IN + USHRT_MAX,
};

/*
 *      Equivalent of ipv4 struct ip
 */
struct frag_queue {
        struct inet_frag_queue  q;

        int                     iif;
        __u16                   nhoffset;
        u8                      ecn;
};

#if IS_ENABLED(CONFIG_IPV6)
static inline void ip6frag_init(struct inet_frag_queue *q, const void *a)
{
        struct frag_queue *fq = container_of(q, struct frag_queue, q);
        const struct frag_v6_compare_key *key = a;

        q->key.v6 = *key;
        fq->ecn = 0;
}

static inline u32 ip6frag_key_hashfn(const void *data, u32 len, u32 seed)
{
        return jhash2(data,
                      sizeof(struct frag_v6_compare_key) / sizeof(u32), seed);
}

static inline u32 ip6frag_obj_hashfn(const void *data, u32 len, u32 seed)
{
        const struct inet_frag_queue *fq = data;

        return jhash2((const u32 *)&fq->key.v6,
                      sizeof(struct frag_v6_compare_key) / sizeof(u32), seed);
}

static inline int
ip6frag_obj_cmpfn(struct rhashtable_compare_arg *arg, const void *ptr)
{
        const struct frag_v6_compare_key *key = arg->key;
        const struct inet_frag_queue *fq = ptr;

        return !!memcmp(&fq->key, key, sizeof(*key));
}

static inline void
ip6frag_expire_frag_queue(struct net *net, struct frag_queue *fq)
{
        struct net_device *dev = NULL;
        struct sk_buff *head;
        int refs = 1;

        rcu_read_lock();
        spin_lock(&fq->q.lock);

        if (fq->q.flags & INET_FRAG_COMPLETE)
                goto out;

        fq->q.flags |= INET_FRAG_DROP;
        inet_frag_kill(&fq->q, &refs);

        /* Paired with the WRITE_ONCE() in fqdir_pre_exit(). */
        if (READ_ONCE(fq->q.fqdir->dead)) {
                inet_frag_queue_flush(&fq->q, 0);
                goto out;
        }

        dev = dev_get_by_index_rcu(net, fq->iif);
        if (!dev)
                goto out;

        __IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMFAILS);
        __IP6_INC_STATS(net, __in6_dev_get(dev), IPSTATS_MIB_REASMTIMEOUT);

        /* Don't send error if the first segment did not arrive. */
        if (!(fq->q.flags & INET_FRAG_FIRST_IN))
                goto out;

        /* sk_buff::dev and sk_buff::rbnode are unionized. So we
         * pull the head out of the tree in order to be able to
         * deal with head->dev.
         */
        head = inet_frag_pull_head(&fq->q);
        if (!head)
                goto out;

        head->dev = dev;
        spin_unlock(&fq->q.lock);

        icmpv6_send(head, ICMPV6_TIME_EXCEED, ICMPV6_EXC_FRAGTIME, 0);
        kfree_skb_reason(head, SKB_DROP_REASON_FRAG_REASM_TIMEOUT);
        goto out_rcu_unlock;

out:
        spin_unlock(&fq->q.lock);
out_rcu_unlock:
        rcu_read_unlock();
        inet_frag_putn(&fq->q, refs);
}

/* Check if the upper layer header is truncated in the first fragment. */
static inline bool
ipv6frag_thdr_truncated(struct sk_buff *skb, int start, u8 *nexthdrp)
{
        u8 nexthdr = *nexthdrp;
        __be16 frag_off;
        int offset;

        offset = ipv6_skip_exthdr(skb, start, &nexthdr, &frag_off);
        if (offset < 0 || (frag_off & htons(IP6_OFFSET)))
                return false;
        switch (nexthdr) {
        case NEXTHDR_TCP:
                offset += sizeof(struct tcphdr);
                break;
        case NEXTHDR_UDP:
                offset += sizeof(struct udphdr);
                break;
        case NEXTHDR_ICMP:
                offset += sizeof(struct icmp6hdr);
                break;
        default:
                offset += 1;
        }
        if (offset > skb->len)
                return true;
        return false;
}

#endif
#endif