/*

 * Written by Solar Designer and placed in the public domain.

 * See crypt-bcrypt.c for more information.

 *

 * This file contains setting-string generation code shared among the

 * MD5, SHA256, and SHA512 hash algorithms, which use very similar

 * setting formats.  Setting-string generation for bcrypt and DES is

 * entirely in crypt-bcrypt.c and crypt-des.c respectively.

 */

#include "crypt-port.h"

#include "crypt-private.h"

#include <errno.h>

#include <stdio.h>

#if INCLUDE_md5 || INCLUDE_sha256 || INCLUDE_sha512

static const unsigned char _xcrypt_itoa64[64 + 1] =

  "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

void

gensalt_sha_rn (char tag, size_t maxsalt, unsigned long defcount,

                unsigned long mincount, unsigned long maxcount,

                unsigned long count,

                const uint8_t *rbytes, size_t nrbytes,

                uint8_t *output, size_t output_size)

{

  if (count == 0)

    count = defcount;

  if (count < mincount || count > maxcount)

    {

      errno = EINVAL;

      return;

    }

  /* We will use more rbytes if available, but at least this much is

     required.  */

  if (nrbytes < 3)

    {

      errno = EINVAL;

      return;

    }

  /* Compute how much space we need.  */

  size_t output_len = 8; /* $x$ssss\0 */

  if (count != defcount)

    {

      output_len += 9; /* rounds=1$ */

      for (unsigned long ceiling = 10; ceiling < count; ceiling *= 10)

        output_len += 1;

    }

  if (output_size < output_len)

    {

      errno = ERANGE;

      return;

    }

  size_t written;

  if (count == defcount)

    {

      output[0] = '$';

      output[1] = (unsigned char)tag;

      output[2] = '$';

      written = 3;

    }

  else

    written = (size_t) snprintf ((char *)output, output_size,

                                 "$%c$rounds=%lu$", tag, count);

  /* The length calculation above should ensure that this is always true.  */

  assert (written + 5 < output_size);

  size_t used_rbytes = 0;

  while (written + 5 < output_size &&

         used_rbytes + 3 < nrbytes &&

         (used_rbytes * 4 / 3) < maxsalt)

    {

      unsigned long value =

        ((unsigned long) (unsigned char) rbytes[used_rbytes + 0] <<  0) |

        ((unsigned long) (unsigned char) rbytes[used_rbytes + 1] <<  8) |

        ((unsigned long) (unsigned char) rbytes[used_rbytes + 2] << 16);

      output[written + 0] = _xcrypt_itoa64[value & 0x3f];

      output[written + 1] = _xcrypt_itoa64[(value >> 6) & 0x3f];

      output[written + 2] = _xcrypt_itoa64[(value >> 12) & 0x3f];

      output[written + 3] = _xcrypt_itoa64[(value >> 18) & 0x3f];

      written += 4;

      used_rbytes += 3;

    }

  output[written] = '\0';

}

#endif