Function acl_authenticate

phx_percona/percona/sql/sql_acl.cc:11407–11760

Perform the handshake, authorize the client and update thd sctx variables. @param thd thread handle @param com_change_user_pkt_len size of the COM_CHANGE_USER packet (without the first, command, byte) or 0 if it's not a COM_CHANGE_USER (that is, if it's a new connection) @

  @retval 1  error
*/
int
acl_authenticate(THD *thd, uint com_change_user_pkt_len)
{
  int res= CR_OK;
  MPVIO_EXT mpvio;
  Thd_charset_adapter charset_adapter(thd);

  LEX_STRING auth_plugin_name= default_auth_plugin_name;
  enum  enum_server_command command= com_change_user_pkt_len ? COM_CHANGE_USER
                                                             : COM_CONNECT;

  DBUG_ENTER("acl_authenticate");
  compile_time_assert(MYSQL_USERNAME_LENGTH == USERNAME_LENGTH);

  server_mpvio_initialize(thd, &mpvio, &charset_adapter);

  DBUG_PRINT("info", ("com_change_user_pkt_len=%u", com_change_user_pkt_len));

  /*
    Clear thd->db as it points to something, that will be freed when
    connection is closed. We don't want to accidentally free a wrong
    pointer if connect failed.
  */
  thd->reset_db(NULL, 0);

  if (command == COM_CHANGE_USER)
  {
    mpvio.packets_written++; // pretend that a server handshake packet was sent
    mpvio.packets_read++;    // take COM_CHANGE_USER packet into account

    /* Clear variables that are allocated */
    thd->set_user_connect(NULL);

    if (parse_com_change_user_packet(&mpvio, com_change_user_pkt_len))
    {
      if (!thd->is_error())
        login_failed_error(&mpvio, mpvio.auth_info.password_used);
      server_mpvio_update_thd(thd, &mpvio);
      DBUG_RETURN(1);
    }

    DBUG_ASSERT(mpvio.status == MPVIO_EXT::RESTART ||
                mpvio.status == MPVIO_EXT::SUCCESS);
  }
  else
  {
    /* mark the thd as having no scramble yet */
    mpvio.scramble[SCRAMBLE_LENGTH]= 1;
    
    /*
     perform the first authentication attempt, with the default plugin.
     This sends the server handshake packet, reads the client reply
     with a user name, and performs the authentication if everyone has used
     the correct plugin.
    */

    res= do_auth_once(thd, &auth_plugin_name, &mpvio);  
  }