/*
 * Copyright 2017-2019 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <string.h>
#include "internal/sha3.h"

void SHA3_squeeze(uint64_t A[5][5], unsigned char *out, size_t len, size_t r);

void sha3_reset(KECCAK1600_CTX *ctx)
{
    memset(ctx->A, 0, sizeof(ctx->A));
    ctx->bufsz = 0;
}

int sha3_init(KECCAK1600_CTX *ctx, unsigned char pad, size_t bitlen)
{
    size_t bsz = SHA3_BLOCKSIZE(bitlen);

    if (bsz <= sizeof(ctx->buf)) {
        sha3_reset(ctx);
        ctx->block_size = bsz;
        ctx->md_size = bitlen / 8;
        ctx->pad = pad;
        return 1;
    }

    return 0;
}

int keccak_kmac_init(KECCAK1600_CTX *ctx, unsigned char pad, size_t bitlen)
{
    int ret = sha3_init(ctx, pad, bitlen);

    if (ret)
        ctx->md_size *= 2;
    return ret;
}

int sha3_update(KECCAK1600_CTX *ctx, const void *_inp, size_t len)
{
    const unsigned char *inp = _inp;
    size_t bsz = ctx->block_size;
    size_t num, rem;

    if (len == 0)
        return 1;

    if ((num = ctx->bufsz) != 0) {      /* process intermediate buffer? */
        rem = bsz - num;

        if (len < rem) {
            memcpy(ctx->buf + num, inp, len);
            ctx->bufsz += len;
            return 1;
        }
        /*
         * We have enough data to fill or overflow the intermediate
         * buffer. So we append |rem| bytes and process the block,
         * leaving the rest for later processing...
         */
        memcpy(ctx->buf + num, inp, rem);
        inp += rem, len -= rem;
        (void)SHA3_absorb(ctx->A, ctx->buf, bsz, bsz);
        ctx->bufsz = 0;
        /* ctx->buf is processed, ctx->num is guaranteed to be zero */
    }

    if (len >= bsz)
        rem = SHA3_absorb(ctx->A, inp, len, bsz);
    else
        rem = len;

    if (rem) {
        memcpy(ctx->buf, inp + len - rem, rem);
        ctx->bufsz = rem;
    }

    return 1;
}

int sha3_final(unsigned char *md, KECCAK1600_CTX *ctx)
{
    size_t bsz = ctx->block_size;
    size_t num = ctx->bufsz;

    if (ctx->md_size == 0)
        return 1;

    /*
     * Pad the data with 10*1. Note that |num| can be |bsz - 1|
     * in which case both byte operations below are performed on
     * same byte...
     */
    memset(ctx->buf + num, 0, bsz - num);
    ctx->buf[num] = ctx->pad;
    ctx->buf[bsz - 1] |= 0x80;

    (void)SHA3_absorb(ctx->A, ctx->buf, bsz, bsz);

    SHA3_squeeze(ctx->A, md, ctx->md_size, bsz);

    return 1;
}