/*
 * md5.c:   checksum routines
 *
 * ====================================================================
 * Copyright (c) 2000-2004 CollabNet.  All rights reserved.
 *
 * 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 http://subversion.tigris.org/license-1.html.
 * If newer versions of this license are posted there, you may use a
 * newer version instead, at your option.
 *
 * This software consists of voluntary contributions made by many
 * individuals.  For exact contribution history, see the revision
 * history and logs, available at http://subversion.tigris.org/.
 * ====================================================================
 */


#include "svn_md5.h"



/* The MD5 digest for the empty string. */
static const unsigned char svn_md5__empty_string_digest[] = {
  212, 29, 140, 217, 143, 0, 178, 4, 233, 128, 9, 152, 236, 248, 66, 126
};

const unsigned char *
svn_md5_empty_string_digest(void)
{
  return svn_md5__empty_string_digest;
}


const char *
svn_md5_digest_to_cstring_display(const unsigned char digest[],
                                  apr_pool_t *pool)
{
  static const char *hex = "0123456789abcdef";
  char *str = apr_palloc(pool, (APR_MD5_DIGESTSIZE * 2) + 1);
  int i;
  
  for (i = 0; i < APR_MD5_DIGESTSIZE; i++)
    {
      str[i*2]   = hex[digest[i] >> 4];
      str[i*2+1] = hex[digest[i] & 0x0f];
    }
  str[i*2] = '\0';
  
  return str;
}
  

const char *
svn_md5_digest_to_cstring(const unsigned char digest[], apr_pool_t *pool)
{
  static const unsigned char zeros_digest[APR_MD5_DIGESTSIZE] = { 0 };

  if (memcmp(digest, zeros_digest, APR_MD5_DIGESTSIZE) != 0)
    return svn_md5_digest_to_cstring_display(digest, pool);
  else
    return NULL;
}


svn_boolean_t
svn_md5_digests_match(const unsigned char d1[], const unsigned char d2[])
{
  static const unsigned char zeros[APR_MD5_DIGESTSIZE] = { 0 };

  return ((memcmp(d1, zeros, APR_MD5_DIGESTSIZE) == 0)
          || (memcmp(d2, zeros, APR_MD5_DIGESTSIZE) == 0)
          || (memcmp(d1, d2, APR_MD5_DIGESTSIZE) == 0));
}