/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _XFRM_HASH_H
#define _XFRM_HASH_H

#include <linux/xfrm.h>
#include <linux/socket.h>
#include <linux/jhash.h>

static inline unsigned int __xfrm4_addr_hash(const xfrm_address_t *addr)
{
        return ntohl(addr->a4);
}

static inline unsigned int __xfrm6_addr_hash(const xfrm_address_t *addr)
{
        return jhash2((__force u32 *)addr->a6, 4, 0);
}

static inline unsigned int __xfrm4_daddr_saddr_hash(const xfrm_address_t *daddr,
                                                    const xfrm_address_t *saddr)
{
        u32 sum = (__force u32)daddr->a4 + (__force u32)saddr->a4;
        return ntohl((__force __be32)sum);
}

static inline unsigned int __xfrm6_daddr_saddr_hash(const xfrm_address_t *daddr,
                                                    const xfrm_address_t *saddr)
{
        return __xfrm6_addr_hash(daddr) ^ __xfrm6_addr_hash(saddr);
}

static inline u32 __bits2mask32(__u8 bits)
{
        u32 mask32 = 0xffffffff;

        if (bits == 0)
                mask32 = 0;
        else if (bits < 32)
                mask32 <<= (32 - bits);

        return mask32;
}

static inline unsigned int __xfrm4_dpref_spref_hash(const xfrm_address_t *daddr,
                                                    const xfrm_address_t *saddr,
                                                    __u8 dbits,
                                                    __u8 sbits)
{
        return jhash_2words(ntohl(daddr->a4) & __bits2mask32(dbits),
                            ntohl(saddr->a4) & __bits2mask32(sbits),
                            0);
}

static inline unsigned int __xfrm6_pref_hash(const xfrm_address_t *addr,
                                             __u8 prefixlen)
{
        unsigned int pdw;
        unsigned int pbi;
        u32 initval = 0;

        pdw = prefixlen >> 5;     /* num of whole u32 in prefix */
        pbi = prefixlen &  0x1f;  /* num of bits in incomplete u32 in prefix */

        if (pbi) {
                __be32 mask;

                mask = htonl((0xffffffff) << (32 - pbi));

                initval = (__force u32)(addr->a6[pdw] & mask);
        }

        return jhash2((__force u32 *)addr->a6, pdw, initval);
}

static inline unsigned int __xfrm6_dpref_spref_hash(const xfrm_address_t *daddr,
                                                    const xfrm_address_t *saddr,
                                                    __u8 dbits,
                                                    __u8 sbits)
{
        return __xfrm6_pref_hash(daddr, dbits) ^
               __xfrm6_pref_hash(saddr, sbits);
}

static inline unsigned int __xfrm_dst_hash(const xfrm_address_t *daddr,
                                           const xfrm_address_t *saddr,
                                           u32 reqid, unsigned short family,
                                           unsigned int hmask)
{
        unsigned int h = family ^ reqid;
        switch (family) {
        case AF_INET:
                h ^= __xfrm4_daddr_saddr_hash(daddr, saddr);
                break;
        case AF_INET6:
                h ^= __xfrm6_daddr_saddr_hash(daddr, saddr);
                break;
        }
        return (h ^ (h >> 16)) & hmask;
}

static inline unsigned int __xfrm_src_hash(const xfrm_address_t *daddr,
                                           const xfrm_address_t *saddr,
                                           unsigned short family,
                                           unsigned int hmask)
{
        unsigned int h = family;
        switch (family) {
        case AF_INET:
                h ^= __xfrm4_daddr_saddr_hash(daddr, saddr);
                break;
        case AF_INET6:
                h ^= __xfrm6_daddr_saddr_hash(daddr, saddr);
                break;
        }
        return (h ^ (h >> 16)) & hmask;
}

static inline unsigned int
__xfrm_spi_hash(const xfrm_address_t *daddr, __be32 spi, u8 proto,
                unsigned short family, unsigned int hmask)
{
        unsigned int h = (__force u32)spi ^ proto;
        switch (family) {
        case AF_INET:
                h ^= __xfrm4_addr_hash(daddr);
                break;
        case AF_INET6:
                h ^= __xfrm6_addr_hash(daddr);
                break;
        }
        return (h ^ (h >> 10) ^ (h >> 20)) & hmask;
}

static inline unsigned int
__xfrm_seq_hash(u32 seq, unsigned int hmask)
{
        unsigned int h = seq;
        return (h ^ (h >> 10) ^ (h >> 20)) & hmask;
}

static inline unsigned int __idx_hash(u32 index, unsigned int hmask)
{
        return (index ^ (index >> 8)) & hmask;
}

static inline unsigned int __sel_hash(const struct xfrm_selector *sel,
                                      unsigned short family, unsigned int hmask,
                                      u8 dbits, u8 sbits)
{
        const xfrm_address_t *daddr = &sel->daddr;
        const xfrm_address_t *saddr = &sel->saddr;
        unsigned int h = 0;

        switch (family) {
        case AF_INET:
                if (sel->prefixlen_d < dbits ||
                    sel->prefixlen_s < sbits)
                        return hmask + 1;

                h = __xfrm4_dpref_spref_hash(daddr, saddr, dbits, sbits);
                break;

        case AF_INET6:
                if (sel->prefixlen_d < dbits ||
                    sel->prefixlen_s < sbits)
                        return hmask + 1;

                h = __xfrm6_dpref_spref_hash(daddr, saddr, dbits, sbits);
                break;
        }
        h ^= (h >> 16);
        return h & hmask;
}

static inline unsigned int __addr_hash(const xfrm_address_t *daddr,
                                       const xfrm_address_t *saddr,
                                       unsigned short family,
                                       unsigned int hmask,
                                       u8 dbits, u8 sbits)
{
        unsigned int h = 0;

        switch (family) {
        case AF_INET:
                h = __xfrm4_dpref_spref_hash(daddr, saddr, dbits, sbits);
                break;

        case AF_INET6:
                h = __xfrm6_dpref_spref_hash(daddr, saddr, dbits, sbits);
                break;
        }
        h ^= (h >> 16);
        return h & hmask;
}

struct hlist_head *xfrm_hash_alloc(unsigned int sz);
void xfrm_hash_free(struct hlist_head *n, unsigned int sz);

#endif /* _XFRM_HASH_H */