/* $OpenBSD: toeplitz.c,v 1.11 2025/07/07 02:28:50 jsg Exp $ */ /* * Copyright (c) 2009 The DragonFly Project. All rights reserved. * * This code is derived from software contributed to The DragonFly Project * by Sepherosa Ziehau <sepherosa@gmail.com> * * 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 <dlg@openbsd.org> * Copyright (c) 2020 Theo Buehler <tb@openbsd.org> * * 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. */ #include <sys/param.h> #include <sys/systm.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. */ 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. */ stoeplitz_key stoeplitz_random_seed(void) { stoeplitz_key seed; seed = arc4random() & 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 < nitems(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 < nitems(faddr6->s6_addr32); i++) n32 ^= faddr6->s6_addr32[i] ^ laddr6->s6_addr32[i]; n32 ^= fport ^ lport; return (stoeplitz_hash_n32(scache, n32)); } #endif /* INET6 */ uint16_t stoeplitz_hash_eaddr(const struct stoeplitz_cache *scache, const uint8_t ea[static 6]) { const uint16_t *ea16 = (const uint16_t *)ea; return (stoeplitz_hash_n16(scache, ea16[0] ^ ea16[1] ^ ea16[2])); } 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; } }
