text: =pod
  
  =head1 NAME
  
  BIO_socket, BIO_bind, BIO_connect, BIO_listen, BIO_accept_ex, BIO_closesocket - BIO
  socket communication setup routines
  
  =head1 SYNOPSIS
  
   #include <openssl/bio.h>
  
   int BIO_socket(int domain, int socktype, int protocol, int options);
   int BIO_bind(int sock, const BIO_ADDR *addr, int options);
   int BIO_connect(int sock, const BIO_ADDR *addr, int options);
   int BIO_listen(int sock, const BIO_ADDR *addr, int options);
   int BIO_accept_ex(int accept_sock, BIO_ADDR *peer, int options);
   int BIO_closesocket(int sock);
  
  =head1 DESCRIPTION
  
  BIO_socket() creates a socket in the domain B<domain>, of type
  B<socktype> and B<protocol>.  Socket B<options> are currently unused,
  but is present for future use.
  
  BIO_bind() binds the source address and service to a socket and
  may be useful before calling BIO_connect().  The options may include
  B<BIO_SOCK_REUSEADDR>, which is described in L</FLAGS> below.
  
  BIO_connect() connects B<sock> to the address and service given by
  B<addr>.  Connection B<options> may be zero or any combination of
  B<BIO_SOCK_KEEPALIVE>, B<BIO_SOCK_NONBLOCK> and B<BIO_SOCK_NODELAY>.
  The flags are described in L</FLAGS> below.
  
  BIO_listen() has B<sock> start listening on the address and service
  given by B<addr>.  Connection B<options> may be zero or any
  combination of B<BIO_SOCK_KEEPALIVE>, B<BIO_SOCK_NONBLOCK>,
  B<BIO_SOCK_NODELAY>, B<BIO_SOCK_REUSEADDR> and B<BIO_SOCK_V6_ONLY>.
  The flags are described in L</FLAGS> below.
  
  BIO_accept_ex() waits for an incoming connections on the given
  socket B<accept_sock>.  When it gets a connection, the address and
  port of the peer gets stored in B<peer> if that one is non-NULL.
  Accept B<options> may be zero or B<BIO_SOCK_NONBLOCK>, and is applied
  on the accepted socket.  The flags are described in L</FLAGS> below.
  
  BIO_closesocket() closes B<sock>.
  
  =head1 FLAGS
  
  =over 4
  
  =item BIO_SOCK_KEEPALIVE
  
  Enables regular sending of keep-alive messages.
  
  =item BIO_SOCK_NONBLOCK
  
  Sets the socket to non-blocking mode.
  
  =item BIO_SOCK_NODELAY
  
  Corresponds to B<TCP_NODELAY>, and disables the Nagle algorithm.  With
  this set, any data will be sent as soon as possible instead of being
  buffered until there's enough for the socket to send out in one go.
  
  =item BIO_SOCK_REUSEADDR
  
  Try to reuse the address and port combination for a recently closed
  port.
  
  =item BIO_SOCK_V6_ONLY
  
  When creating an IPv6 socket, make it only listen for IPv6 addresses
  and not IPv4 addresses mapped to IPv6.
  
  =back
  
  These flags are bit flags, so they are to be combined with the
  C<|> operator, for example:
  
   BIO_connect(sock, addr, BIO_SOCK_KEEPALIVE | BIO_SOCK_NONBLOCK);
  
  =head1 RETURN VALUES
  
  BIO_socket() returns the socket number on success or B<INVALID_SOCKET>
  (-1) on error.  When an error has occurred, the OpenSSL error stack
  will hold the error data and errno has the system error.
  
  BIO_bind(), BIO_connect() and BIO_listen() return 1 on success or 0 on error.
  When an error has occurred, the OpenSSL error stack will hold the error
  data and errno has the system error.
  
  BIO_accept_ex() returns the accepted socket on success or
  B<INVALID_SOCKET> (-1) on error.  When an error has occurred, the
  OpenSSL error stack will hold the error data and errno has the system
  error.
  
  =head1 SEE ALSO
  
  L<BIO_ADDR(3)>
  
  =head1 HISTORY
  
  BIO_gethostname(), BIO_get_port(), BIO_get_host_ip(),
  BIO_get_accept_socket() and BIO_accept() were deprecated in OpenSSL 1.1.0.
  Use the functions described above instead.
  
  =head1 COPYRIGHT
  
  Copyright 2016-2019 The OpenSSL Project Authors. All Rights Reserved.
  
  Licensed under the OpenSSL license (the "License").  You may not use
  this file except in compliance with the License.  You can obtain a copy
  in the file LICENSE in the source distribution or at
  L<https://www.openssl.org/source/license.html>.
  
  =cut
  