/***************************************************************************

 *                                  _   _ ____  _

 *  Project                     ___| | | |  _ \| |

 *                             / __| | | | |_) | |

 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) 1998 - 2022, Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms

 * are also available at https://curl.se/docs/copyright.html.

 *

 * You may opt to use, copy, modify, merge, publish, distribute and/or sell

 * copies of the Software, and permit persons to whom the Software is

 * furnished to do so, under the terms of the COPYING file.

 *

 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY

 * KIND, either express or implied.

 *

 * SPDX-License-Identifier: curl

 *

 * RFC2104 Keyed-Hashing for Message Authentication

 *

 ***************************************************************************/

#include "curl_setup.h"

#ifndef CURL_DISABLE_CRYPTO_AUTH

#include <curl/curl.h>

#include "curl_hmac.h"

#include "curl_memory.h"

#include "warnless.h"

/* The last #include file should be: */

#include "memdebug.h"

/*

 * Generic HMAC algorithm.

 *

 *   This module computes HMAC digests based on any hash function. Parameters

 * and computing procedures are set-up dynamically at HMAC computation context

 * initialization.

 */

static const unsigned char hmac_ipad = 0x36;

static const unsigned char hmac_opad = 0x5C;

struct HMAC_context *

Curl_HMAC_init(const struct HMAC_params *hashparams,

               const unsigned char *key,

               unsigned int keylen)

{

  size_t i;

  struct HMAC_context *ctxt;

  unsigned char *hkey;

  unsigned char b;

  /* Create HMAC context. */

  i = sizeof(*ctxt) + 2 * hashparams->hmac_ctxtsize +

    hashparams->hmac_resultlen;

  ctxt = malloc(i);

  if(!ctxt)

    return ctxt;

  ctxt->hmac_hash = hashparams;

  ctxt->hmac_hashctxt1 = (void *) (ctxt + 1);

  ctxt->hmac_hashctxt2 = (void *) ((char *) ctxt->hmac_hashctxt1 +

      hashparams->hmac_ctxtsize);

  /* If the key is too long, replace it by its hash digest. */

  if(keylen > hashparams->hmac_maxkeylen) {

    (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);

    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, key, keylen);

    hkey = (unsigned char *) ctxt->hmac_hashctxt2 + hashparams->hmac_ctxtsize;

    (*hashparams->hmac_hfinal)(hkey, ctxt->hmac_hashctxt1);

    key = hkey;

    keylen = hashparams->hmac_resultlen;

  }

  /* Prime the two hash contexts with the modified key. */

  (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt1);

  (*hashparams->hmac_hinit)(ctxt->hmac_hashctxt2);

  for(i = 0; i < keylen; i++) {

    b = (unsigned char)(*key ^ hmac_ipad);

    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &b, 1);

    b = (unsigned char)(*key++ ^ hmac_opad);

    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &b, 1);

  }

  for(; i < hashparams->hmac_maxkeylen; i++) {

    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt1, &hmac_ipad, 1);

    (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2, &hmac_opad, 1);

  }

  /* Done, return pointer to HMAC context. */

  return ctxt;

}

int Curl_HMAC_update(struct HMAC_context *ctxt,

                     const unsigned char *data,

                     unsigned int len)

{

  /* Update first hash calculation. */

  (*ctxt->hmac_hash->hmac_hupdate)(ctxt->hmac_hashctxt1, data, len);

  return 0;

}

int Curl_HMAC_final(struct HMAC_context *ctxt, unsigned char *result)

{

  const struct HMAC_params *hashparams = ctxt->hmac_hash;

  /* Do not get result if called with a null parameter: only release

     storage. */

  if(!result)

    result = (unsigned char *) ctxt->hmac_hashctxt2 +

     ctxt->hmac_hash->hmac_ctxtsize;

  (*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt1);

  (*hashparams->hmac_hupdate)(ctxt->hmac_hashctxt2,

   result, hashparams->hmac_resultlen);

  (*hashparams->hmac_hfinal)(result, ctxt->hmac_hashctxt2);

  free((char *) ctxt);

  return 0;

}

/*

 * Curl_hmacit()

 *

 * This is used to generate a HMAC hash, for the specified input data, given

 * the specified hash function and key.

 *

 * Parameters:

 *

 * hashparams [in]     - The hash function (Curl_HMAC_MD5).

 * key        [in]     - The key to use.

 * keylen     [in]     - The length of the key.

 * data       [in]     - The data to encrypt.

 * datalen    [in]     - The length of the data.

 * output     [in/out] - The output buffer.

 *

 * Returns CURLE_OK on success.

 */

CURLcode Curl_hmacit(const struct HMAC_params *hashparams,

                     const unsigned char *key, const size_t keylen,

                     const unsigned char *data, const size_t datalen,

                     unsigned char *output)

{

  struct HMAC_context *ctxt =

    Curl_HMAC_init(hashparams, key, curlx_uztoui(keylen));

  if(!ctxt)

    return CURLE_OUT_OF_MEMORY;

  /* Update the digest with the given challenge */

  Curl_HMAC_update(ctxt, data, curlx_uztoui(datalen));

  /* Finalise the digest */

  Curl_HMAC_final(ctxt, output);

  return CURLE_OK;

}

#endif /* CURL_DISABLE_CRYPTO_AUTH */