Function sha256_password_authenticate

phx_percona/percona/sql/sql_acl.cc:12239–12406

*/

static int sha256_password_authenticate(MYSQL_PLUGIN_VIO *vio,
                                        MYSQL_SERVER_AUTH_INFO *info)
{
  uchar *pkt;
  int pkt_len;
  char  *user_salt_begin;
  char  *user_salt_end;
  char scramble[SCRAMBLE_LENGTH + 1];
  char stage2[CRYPT_MAX_PASSWORD_SIZE + 1];
  String scramble_response_packet;
#if !defined(HAVE_YASSL)
  int cipher_length= 0;
  unsigned char plain_text[MAX_CIPHER_LENGTH];
  RSA *private_key= NULL;
  RSA *public_key= NULL;
#endif

  DBUG_ENTER("sha256_password_authenticate");

  generate_user_salt(scramble, SCRAMBLE_LENGTH + 1);

  /*
    Note: The nonce is split into 8 + 12 bytes according to
http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::HandshakeV10
    Native authentication sent 20 bytes + '\0' character = 21 bytes.
    This plugin must do the same to stay consistent with historical behavior 
    if it is set to operate as a default plugin.
  */
  scramble[SCRAMBLE_LENGTH] = '\0';
  if (vio->write_packet(vio, (unsigned char *) scramble, SCRAMBLE_LENGTH + 1))
    DBUG_RETURN(CR_ERROR);

  /*
    After the call to read_packet() the user name will appear in
    mpvio->acl_user and info will contain current data.
  */
  if ((pkt_len= vio->read_packet(vio, &pkt)) == -1)
    DBUG_RETURN(CR_ERROR);

  /*
    If first packet is a 0 byte then the client isn't sending any password
    else the client will send a password.
  */
  if (pkt_len == 1 && *pkt == 0)
  {
    info->password_used= PASSWORD_USED_NO;
    /*
      Send OK signal; the authentication might still be rejected based on
      host mask.
    */
    if (info->auth_string_length == 0)
      DBUG_RETURN(CR_OK);
    else
      DBUG_RETURN(CR_ERROR);
  }
  else    
    info->password_used= PASSWORD_USED_YES;