ec251fe7d5
gcc 7 adds -Wimplicit-fallthrough=3 to -Wextra. There are a few ways we could deal with that. After we take into account the need to stay compatible with older versions of the compiler (and other compilers), I don't think adding __attribute__((fallthrough)), even as a macro, is worth the trouble. It sticks out too much, a comment is just as good. But gcc has some very specific requiremnts how the comment should look. Adjust it the specific form that it likes. I don't think the extra stuff we had in those comments was adding much value. (Note: the documentation seems to be wrong, and seems to describe a different pattern from the one that is actually used. I guess either the docs or the code will have to change before gcc 7 is finalized.)
201 lines
7.2 KiB
C
201 lines
7.2 KiB
C
/*
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SipHash reference C implementation
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Written in 2012 by
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Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
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Daniel J. Bernstein <djb@cr.yp.to>
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To the extent possible under law, the author(s) have dedicated all copyright
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and related and neighboring rights to this software to the public domain
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worldwide. This software is distributed without any warranty.
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You should have received a copy of the CC0 Public Domain Dedication along with
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this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
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(Minimal changes made by Lennart Poettering, to make clean for inclusion in systemd)
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(Refactored by Tom Gundersen to split up in several functions and follow systemd
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coding style)
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*/
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#include <stdio.h>
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#include "macro.h"
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#include "siphash24.h"
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#include "unaligned.h"
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static inline uint64_t rotate_left(uint64_t x, uint8_t b) {
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assert(b < 64);
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return (x << b) | (x >> (64 - b));
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}
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static inline void sipround(struct siphash *state) {
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assert(state);
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state->v0 += state->v1;
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state->v1 = rotate_left(state->v1, 13);
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state->v1 ^= state->v0;
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state->v0 = rotate_left(state->v0, 32);
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state->v2 += state->v3;
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state->v3 = rotate_left(state->v3, 16);
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state->v3 ^= state->v2;
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state->v0 += state->v3;
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state->v3 = rotate_left(state->v3, 21);
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state->v3 ^= state->v0;
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state->v2 += state->v1;
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state->v1 = rotate_left(state->v1, 17);
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state->v1 ^= state->v2;
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state->v2 = rotate_left(state->v2, 32);
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}
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void siphash24_init(struct siphash *state, const uint8_t k[16]) {
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uint64_t k0, k1;
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assert(state);
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assert(k);
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k0 = unaligned_read_le64(k);
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k1 = unaligned_read_le64(k + 8);
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*state = (struct siphash) {
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/* "somepseudorandomlygeneratedbytes" */
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.v0 = 0x736f6d6570736575ULL ^ k0,
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.v1 = 0x646f72616e646f6dULL ^ k1,
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.v2 = 0x6c7967656e657261ULL ^ k0,
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.v3 = 0x7465646279746573ULL ^ k1,
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.padding = 0,
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.inlen = 0,
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};
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}
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void siphash24_compress(const void *_in, size_t inlen, struct siphash *state) {
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const uint8_t *in = _in;
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const uint8_t *end = in + inlen;
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size_t left = state->inlen & 7;
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uint64_t m;
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assert(in);
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assert(state);
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/* Update total length */
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state->inlen += inlen;
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/* If padding exists, fill it out */
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if (left > 0) {
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for ( ; in < end && left < 8; in ++, left ++)
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state->padding |= ((uint64_t) *in) << (left * 8);
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if (in == end && left < 8)
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/* We did not have enough input to fill out the padding completely */
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return;
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#ifdef DEBUG
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printf("(%3zu) v0 %08x %08x\n", state->inlen, (uint32_t) (state->v0 >> 32), (uint32_t) state->v0);
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printf("(%3zu) v1 %08x %08x\n", state->inlen, (uint32_t) (state->v1 >> 32), (uint32_t) state->v1);
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printf("(%3zu) v2 %08x %08x\n", state->inlen, (uint32_t) (state->v2 >> 32), (uint32_t) state->v2);
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printf("(%3zu) v3 %08x %08x\n", state->inlen, (uint32_t) (state->v3 >> 32), (uint32_t) state->v3);
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printf("(%3zu) compress padding %08x %08x\n", state->inlen, (uint32_t) (state->padding >> 32), (uint32_t)state->padding);
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#endif
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state->v3 ^= state->padding;
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sipround(state);
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sipround(state);
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state->v0 ^= state->padding;
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state->padding = 0;
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}
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end -= (state->inlen % sizeof(uint64_t));
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for ( ; in < end; in += 8) {
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m = unaligned_read_le64(in);
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#ifdef DEBUG
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printf("(%3zu) v0 %08x %08x\n", state->inlen, (uint32_t) (state->v0 >> 32), (uint32_t) state->v0);
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printf("(%3zu) v1 %08x %08x\n", state->inlen, (uint32_t) (state->v1 >> 32), (uint32_t) state->v1);
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printf("(%3zu) v2 %08x %08x\n", state->inlen, (uint32_t) (state->v2 >> 32), (uint32_t) state->v2);
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printf("(%3zu) v3 %08x %08x\n", state->inlen, (uint32_t) (state->v3 >> 32), (uint32_t) state->v3);
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printf("(%3zu) compress %08x %08x\n", state->inlen, (uint32_t) (m >> 32), (uint32_t) m);
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#endif
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state->v3 ^= m;
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sipround(state);
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sipround(state);
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state->v0 ^= m;
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}
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left = state->inlen & 7;
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switch (left) {
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case 7:
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state->padding |= ((uint64_t) in[6]) << 48;
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/* fall through */
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case 6:
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state->padding |= ((uint64_t) in[5]) << 40;
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/* fall through */
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case 5:
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state->padding |= ((uint64_t) in[4]) << 32;
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/* fall through */
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case 4:
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state->padding |= ((uint64_t) in[3]) << 24;
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/* fall through */
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case 3:
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state->padding |= ((uint64_t) in[2]) << 16;
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/* fall through */
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case 2:
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state->padding |= ((uint64_t) in[1]) << 8;
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/* fall through */
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case 1:
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state->padding |= ((uint64_t) in[0]);
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/* fall through */
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case 0:
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break;
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}
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}
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uint64_t siphash24_finalize(struct siphash *state) {
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uint64_t b;
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assert(state);
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b = state->padding | (((uint64_t) state->inlen) << 56);
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#ifdef DEBUG
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printf("(%3zu) v0 %08x %08x\n", state->inlen, (uint32_t) (state->v0 >> 32), (uint32_t) state->v0);
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printf("(%3zu) v1 %08x %08x\n", state->inlen, (uint32_t) (state->v1 >> 32), (uint32_t) state->v1);
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printf("(%3zu) v2 %08x %08x\n", state->inlen, (uint32_t) (state->v2 >> 32), (uint32_t) state->v2);
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printf("(%3zu) v3 %08x %08x\n", state->inlen, (uint32_t) (state->v3 >> 32), (uint32_t) state->v3);
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printf("(%3zu) padding %08x %08x\n", state->inlen, (uint32_t) (state->padding >> 32), (uint32_t) state->padding);
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#endif
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state->v3 ^= b;
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sipround(state);
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sipround(state);
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state->v0 ^= b;
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#ifdef DEBUG
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printf("(%3zu) v0 %08x %08x\n", state->inlen, (uint32_t) (state->v0 >> 32), (uint32_t) state->v0);
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printf("(%3zu) v1 %08x %08x\n", state->inlen, (uint32_t) (state->v1 >> 32), (uint32_t) state->v1);
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printf("(%3zu) v2 %08x %08x\n", state->inlen, (uint32_t) (state->v2 >> 32), (uint32_t) state->v2);
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printf("(%3zu) v3 %08x %08x\n", state->inlen, (uint32_t) (state->v3 >> 32), (uint32_t) state->v3);
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#endif
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state->v2 ^= 0xff;
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sipround(state);
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sipround(state);
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sipround(state);
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sipround(state);
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return state->v0 ^ state->v1 ^ state->v2 ^ state->v3;
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}
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uint64_t siphash24(const void *in, size_t inlen, const uint8_t k[16]) {
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struct siphash state;
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assert(in);
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assert(k);
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siphash24_init(&state, k);
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siphash24_compress(in, inlen, &state);
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return siphash24_finalize(&state);
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}
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