/*

 * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>

 *

 * Permission is hereby granted, free of charge, to any person obtaining 

 * a copy of this software and associated documentation files (the

 * "Software"), to deal in the Software without restriction, including

 * without limitation the rights to use, copy, modify, merge, publish,

 * distribute, sublicense, and/or sell copies of the Software, and to

 * permit persons to whom the Software is furnished to do so, subject to

 * the following conditions:

 *

 * The above copyright notice and this permission notice shall be 

 * included in all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 

 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 

 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS

 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN

 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN

 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE

 * SOFTWARE.

 */

#include "inner.h"

/* see inner.h */

void

br_tls_phash(void *dst, size_t len,

  const br_hash_class *dig,

  const void *secret, size_t secret_len, const char *label,

  size_t seed_num, const br_tls_prf_seed_chunk *seed)

{

  unsigned char *buf;

  unsigned char tmp[64], a[64];

  br_hmac_key_context kc;

  br_hmac_context hc;

  size_t label_len, hlen, u;

  if (len == 0) {

    return;

  }

  buf = dst;

  for (label_len = 0; label[label_len]; label_len ++);

  hlen = br_digest_size(dig);

  br_hmac_key_init(&kc, dig, secret, secret_len);

  br_hmac_init(&hc, &kc, 0);

  br_hmac_update(&hc, label, label_len);

  for (u = 0; u < seed_num; u ++) {

    br_hmac_update(&hc, seed[u].data, seed[u].len);

  }

  br_hmac_out(&hc, a);

  for (;;) {

    br_hmac_init(&hc, &kc, 0);

    br_hmac_update(&hc, a, hlen);

    br_hmac_update(&hc, label, label_len);

    for (u = 0; u < seed_num; u ++) {

      br_hmac_update(&hc, seed[u].data, seed[u].len);

    }

    br_hmac_out(&hc, tmp);

    for (u = 0; u < hlen && u < len; u ++) {

      buf[u] ^= tmp[u];

    }

    buf += u;

    len -= u;

    if (len == 0) {

      return;

    }

    br_hmac_init(&hc, &kc, 0);

    br_hmac_update(&hc, a, hlen);

    br_hmac_out(&hc, a);

  }

}