mysql5/mysql-5.7.27/sql/conn_handler/socket_connection.h

/*
   Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
*/

#ifndef SOCKET_CONNECTION_INCLUDED
#define SOCKET_CONNECTION_INCLUDED

#include "my_global.h"               // uint
#include "my_thread.h"
#include "pfs_socket_provider.h"
#include "mysql/psi/mysql_socket.h"  // MYSQL_SOCKET

#include <map>
#include <string>
#ifdef HAVE_POLL_H
#include <poll.h>
#endif

class Channel_info;
class THD;


extern const char *MY_BIND_ALL_ADDRESSES;
#ifdef HAVE_PSI_STATEMENT_INTERFACE
extern PSI_statement_info stmt_info_new_packet;
#endif


/**
  Key Comparator for socket_map_t used in Mysqld_socket_listener
*/
struct Socket_lt_type
{
  bool operator()(const MYSQL_SOCKET& s1, const MYSQL_SOCKET& s2) const
  {
    return mysql_socket_getfd(s1) < mysql_socket_getfd(s2);
  }
};


/**
  Typedef representing socket map type which hold the sockets and a corresponding
  bool which is true if it is unix socket and false for tcp socket.
*/
typedef std::map<MYSQL_SOCKET, bool, Socket_lt_type> socket_map_t;

// iterator type for socket map type.
typedef std::map<MYSQL_SOCKET, bool, Socket_lt_type>::iterator
  socket_map_iterator_t;


/**
  This class represents the Mysqld_socket_listener which prepare the
  listener sockets to recieve connection events from the client. The
  Mysqld_socket_listener may be composed of either or both a tcp socket
  which listen on a default mysqld tcp port or a user specified  port
  via mysqld command-line  and a unix socket which is bind to a mysqld
  defaul pathname.
*/
class Mysqld_socket_listener
{
  std::string m_bind_addr_str; // IP address string
  uint m_tcp_port; // TCP port to bind to
  uint m_backlog; // backlog specifying length of pending connection queue
  uint m_port_timeout; // port timeout value
  std::string m_unix_sockname; // unix socket pathname to bind to
  bool m_unlink_sockname; // Unlink socket & lock file if true.
  /*
    Map indexed by MYSQL socket fds and correspoding bool to distinguish
    between unix and tcp socket.
  */
  socket_map_t m_socket_map; // map indexed by mysql socket fd and index

  uint m_error_count; // Internal variable for maintaining error count.

#ifdef HAVE_POLL
  static const int MAX_SOCKETS=2;
  struct poll_info_t
  {
    struct pollfd m_fds[MAX_SOCKETS];
    MYSQL_SOCKET m_pfs_fds[MAX_SOCKETS];
  };
  // poll related info. used in poll for listening to connection events.
  poll_info_t m_poll_info;
#else
  struct select_info_t
  {
    fd_set  m_read_fds,m_client_fds;
    my_socket m_max_used_connection;
    select_info_t() : m_max_used_connection(0)
    { FD_ZERO(&m_client_fds); }
  };
  // select info for used in select for listening to connection events.
  select_info_t m_select_info;
#endif // HAVE_POLL

#ifdef HAVE_LIBWRAP
  const char *m_libwrap_name;
  int m_deny_severity;
#endif

  /** Number of connection errors when selecting on the listening port */
  static ulong connection_errors_select;
  /** Number of connection errors when accepting sockets in the listening port. */
  static ulong connection_errors_accept;
  /** Number of connection errors from TCP wrappers. */
  static ulong connection_errors_tcpwrap;

public:
  static ulong get_connection_errors_select()
  {
    return connection_errors_select;
  }

  static ulong get_connection_errors_accept()
  {
    return connection_errors_accept;
  }

  static ulong get_connection_errors_tcpwrap()
  {
    return connection_errors_tcpwrap;
  }

  /**
    Constructor to setup a listener for listen to connect events from
    clients.

    @param   bind_addr_str  IP address used in bind
    @param   tcp_port       TCP port to bind to
    @param   backlog        backlog specifying length of pending
                            connection queue used in listen.
    @param   port_timeout   portname.
    @param   unix_sockname  pathname for unix socket to bind to
  */
  Mysqld_socket_listener(std::string bind_addr_str, uint tcp_port,
                         uint backlog, uint port_timeout,
                         std::string unix_sockname);

  /**
    Set up a listener - set of sockets to listen for connection events
    from clients.

    @retval false  listener sockets setup to be used to listen for connect events
            true   failure in setting up the listener.
  */
  bool setup_listener();

  /**
    The body of the event loop that listen for connection events from clients.

    @retval Channel_info   Channel_info object abstracting the connected client
                           details for processing this connection.
  */
  Channel_info* listen_for_connection_event();

  /**
    Close the listener.
  */
  void close_listener();

  ~Mysqld_socket_listener()
  {
    if (!m_socket_map.empty())
      close_listener();
  }
};

#endif // SOCKET_CONNECTION_INCLUDED.