/* $OpenBSD: toeplitz.c,v 1.9 2020/09/01 19:18:26 tb Exp $ */

/*
* Copyright (c) 2009 The DragonFly Project.  All rights reserved.
*
* This code is derived from software contributed to The DragonFly Project
* by Sepherosa Ziehau <[email protected]>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
* 3. Neither the name of The DragonFly Project nor the names of its
*    contributors may be used to endorse or promote products derived
*    from this software without specific, prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
* COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

/*
* Copyright (c) 2019 David Gwynne <[email protected]>
* Copyright (c) 2020 Theo Buehler <[email protected]>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

/*-
* Copyright (c) 2019 Ryo Shimizu
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/cprng.h>

#include <netinet/in.h>

#include <net/toeplitz.h>

/*
* symmetric toeplitz
*/

static stoeplitz_key            stoeplitz_keyseed = STOEPLITZ_KEYSEED;
static struct stoeplitz_cache   stoeplitz_syskey_cache;
const struct stoeplitz_cache *const
                               stoeplitz_cache = &stoeplitz_syskey_cache;

/* parity of n16: count (mod 2) of ones in the binary representation. */
static int
parity(uint16_t n16)
{
       n16 = ((n16 & 0xaaaa) >> 1) ^ (n16 & 0x5555);
       n16 = ((n16 & 0xcccc) >> 2) ^ (n16 & 0x3333);
       n16 = ((n16 & 0xf0f0) >> 4) ^ (n16 & 0x0f0f);
       n16 = ((n16 & 0xff00) >> 8) ^ (n16 & 0x00ff);

       return (n16);
}

/*
* The Toeplitz matrix obtained from a seed is invertible if and only if the
* parity of the seed is 1. Generate such a seed uniformly at random.
*/
static stoeplitz_key
stoeplitz_random_seed(void)
{
       stoeplitz_key seed;

       seed = cprng_strong32() & UINT16_MAX;
       if (parity(seed) == 0)
               seed ^= 1;

       return (seed);
}

void
stoeplitz_init(void)
{
       stoeplitz_keyseed = stoeplitz_random_seed();
       stoeplitz_cache_init(&stoeplitz_syskey_cache, stoeplitz_keyseed);
}

#define NBSK (NBBY * sizeof(stoeplitz_key))

/*
* The Toeplitz hash of a 16-bit number considered as a column vector over
* the field with two elements is calculated as a matrix multiplication with
* a 16x16 circulant Toeplitz matrix T generated by skey.
*
* The first eight columns H of T generate the remaining eight columns using
* the byteswap operation J = swap16:  T = [H JH].  Thus, the Toeplitz hash of
* n = [hi lo] is computed via the formula T * n = (H * hi) ^ swap16(H * lo).
*
* Therefore the results H * val for all values of a byte are cached in scache.
*/
void
stoeplitz_cache_init(struct stoeplitz_cache *scache, stoeplitz_key skey)
{
       uint16_t column[NBBY];
       unsigned int b, shift, val;

       bzero(column, sizeof(column));

       /* Calculate the first eight columns H of the Toeplitz matrix T. */
       for (b = 0; b < NBBY; ++b)
               column[b] = skey << b | skey >> (NBSK - b);

       /* Cache the results of H * val for all possible values of a byte. */
       for (val = 0; val < 256; ++val) {
               uint16_t res = 0;

               for (b = 0; b < NBBY; ++b) {
                       shift = NBBY - b - 1;
                       if (val & (1 << shift))
                               res ^= column[b];
               }
               scache->bytes[val] = res;
       }
}

uint16_t
stoeplitz_hash_ip4(const struct stoeplitz_cache *scache,
   in_addr_t faddr, in_addr_t laddr)
{
       return (stoeplitz_hash_n32(scache, faddr ^ laddr));
}

uint16_t
stoeplitz_hash_ip4port(const struct stoeplitz_cache *scache,
   in_addr_t faddr, in_addr_t laddr, in_port_t fport, in_port_t lport)
{
       return (stoeplitz_hash_n32(scache, faddr ^ laddr ^ fport ^ lport));
}

#ifdef INET6
uint16_t
stoeplitz_hash_ip6(const struct stoeplitz_cache *scache,
   const struct in6_addr *faddr6, const struct in6_addr *laddr6)
{
       uint32_t n32 = 0;
       size_t i;

       for (i = 0; i < __arraycount(faddr6->s6_addr32); i++)
               n32 ^= faddr6->s6_addr32[i] ^ laddr6->s6_addr32[i];

       return (stoeplitz_hash_n32(scache, n32));
}

uint16_t
stoeplitz_hash_ip6port(const struct stoeplitz_cache *scache,
   const struct in6_addr *faddr6, const struct in6_addr *laddr6,
   in_port_t fport, in_port_t lport)
{
       uint32_t n32 = 0;
       size_t i;

       for (i = 0; i < __arraycount(faddr6->s6_addr32); i++)
               n32 ^= faddr6->s6_addr32[i] ^ laddr6->s6_addr32[i];

       n32 ^= fport ^ lport;

       return (stoeplitz_hash_n32(scache, n32));
}
#endif /* INET6 */

void
stoeplitz_to_key(void *key, size_t klen)
{
       uint8_t *k = key;
       uint16_t skey = htons(stoeplitz_keyseed);
       size_t i;

       KASSERT((klen % 2) == 0);

       for (i = 0; i < klen; i += sizeof(skey)) {
               k[i + 0] = skey >> 8;
               k[i + 1] = skey;
       }
}

/*
* e.g.)
*
* struct in_addr src, dst;
* uint16_t srcport, dstport;
* toeplitz_vhash(rsskey[], sizeof(rsskey),
*                    &src, sizeof(src),
*                    &dst, sizeof(dst),
*                    &srcport, sizeof(srcport),
*                    &dstport, sizeof(dstport),
*                    NULL);
*
* struct in6_addr src6, dst6;
* toeplitz_vhash(rsskey[], sizeof(rsskey),
*                    &src6, sizeof(src6),
*                    &dst6, sizeof(dst6),
*                    NULL);
*
* struct ip *ip;
* struct tcphdr *tcp;
* toeplitz_vhash(rsskey[], sizeof(rsskey),
*                    &ip->ip_src, sizeof(ip->ip_src),
*                    &ip->ip_dst, sizeof(ip->ip_dst),
*                    &tcp->th_sport, sizeof(tcp->th_sport),
*                    &tcp->th_dport, sizeof(tcp->th_dport),
*                    NULL);
*
*/
uint32_t
toeplitz_vhash(const uint8_t *keyp, size_t keylen, ...)
{
       va_list ap;
       uint32_t hash, v;
       size_t datalen;
       uint8_t *datap, key, data;
       const uint8_t *keyend;

       keyend = keyp + keylen;

       /* first 32bit is initial vector */
       v = *keyp++;
       v <<= 8;
       v |= *keyp++;
       v <<= 8;
       v |= *keyp++;
       v <<= 8;
       v |= *keyp++;

       hash = 0;
       va_start(ap, keylen);

       while ((datap = va_arg(ap, uint8_t *)) != NULL) {
               for (datalen = va_arg(ap, size_t); datalen > 0; datalen--) {
                       /* fetch key and input data by 8bit */
                       if (keyp < keyend)
                               key = *keyp++;
                       else
                               key = 0;
                       data = *datap++;

#define XOR_AND_FETCH_BIT(x)                    \
                       if (data & __BIT(x))            \
                               hash ^= v;              \
                       v <<= 1;                        \
                       if (key & __BIT(x))             \
                               v |= 1;

                       XOR_AND_FETCH_BIT(7);
                       XOR_AND_FETCH_BIT(6);
                       XOR_AND_FETCH_BIT(5);
                       XOR_AND_FETCH_BIT(4);
                       XOR_AND_FETCH_BIT(3);
                       XOR_AND_FETCH_BIT(2);
                       XOR_AND_FETCH_BIT(1);
                       XOR_AND_FETCH_BIT(0);

#undef XOR_AND_FETCH_BIT
               }
       }
       va_end(ap);

       return hash;
}

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