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

 *                                  _   _ ____  _

 *  Project                     ___| | | |  _ \| |

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

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

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

 *

 * Copyright (C) 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"

#if (defined(USE_CURL_NTLM_CORE) && !defined(USE_WINDOWS_SSPI)) ||    \

  !defined(CURL_DISABLE_AWS) || !defined(CURL_DISABLE_DIGEST_AUTH) || \

  defined(USE_SSL)

#include "curl_hmac.h"

/*

 * Generic HMAC algorithm.

 *

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

 * and computing procedures are setup 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->ctxtsize) + hashparams->resultlen;

  ctxt = curlx_malloc(i);

  if(!ctxt)

    return ctxt;

  ctxt->hash = hashparams;

  ctxt->hashctxt1 = (void *)(ctxt + 1);

  ctxt->hashctxt2 = (void *)((char *)ctxt->hashctxt1 + hashparams->ctxtsize);

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

  if(keylen > hashparams->maxkeylen) {

    if(hashparams->hinit(ctxt->hashctxt1))

      goto fail;

    hashparams->hupdate(ctxt->hashctxt1, key, keylen);

    hkey = (unsigned char *)ctxt->hashctxt2 + hashparams->ctxtsize;

    hashparams->hfinal(hkey, ctxt->hashctxt1);

    key = hkey;

    keylen = hashparams->resultlen;

  }

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

  if(hashparams->hinit(ctxt->hashctxt1) ||

     hashparams->hinit(ctxt->hashctxt2))

    goto fail;

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

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

    hashparams->hupdate(ctxt->hashctxt1, &b, 1);

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

    hashparams->hupdate(ctxt->hashctxt2, &b, 1);

  }

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

    hashparams->hupdate(ctxt->hashctxt1, &hmac_ipad, 1);

    hashparams->hupdate(ctxt->hashctxt2, &hmac_opad, 1);

  }

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

  return ctxt;

fail:

  curlx_free(ctxt);

  return NULL;

}

void Curl_HMAC_update(struct HMAC_context *ctxt,

                      const unsigned char *data,

                      unsigned int len)

{

  /* Update first hash calculation. */

  ctxt->hash->hupdate(ctxt->hashctxt1, data, len);

}

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

{

  const struct HMAC_params *hashparams = ctxt->hash;

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

     storage. */

  if(!output)

    output = (unsigned char *)ctxt->hashctxt2 + ctxt->hash->ctxtsize;

  hashparams->hfinal(output, ctxt->hashctxt1);

  hashparams->hupdate(ctxt->hashctxt2, output, hashparams->resultlen);

  hashparams->hfinal(output, ctxt->hashctxt2);

  curlx_free(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.

 * buf        [in]     - The data to encrypt.

 * buflen     [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, size_t datalen,

                     unsigned char *output)

{

  struct HMAC_context *ctxt;

  if(keylen > UINT_MAX) /* unlikely to ever happen */

    return CURLE_BAD_FUNCTION_ARGUMENT;

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

  if(!ctxt)

    return CURLE_OUT_OF_MEMORY;

  /* Update the digest with the given challenge */

  do {

    unsigned int ilen = (unsigned int)CURLMIN(datalen, UINT_MAX);

    Curl_HMAC_update(ctxt, data, ilen);

    datalen -= ilen;

    data += ilen;

  } while(datalen);

  /* Finalise the digest */

  Curl_HMAC_final(ctxt, output);

  return CURLE_OK;

}

#endif /* Using NTLM (without SSPI) or AWS */