NAME

       BIO_socket, BIO_bind, BIO_connect, BIO_listen, BIO_accept_ex, BIO_closesocket - BIO socket communication
       setup routines

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);

DESCRIPTION

       BIO_socket() creates a socket in the domain domain, of type socktype and protocol.  Socket 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 BIO_SOCK_REUSADDR, which is described in "FLAGS" below.

       BIO_connect() connects sock to the address and service given by addr.  Connection options may be zero or
       any combination of BIO_SOCK_KEEPALIVE, BIO_SOCK_NONBLOCK and BIO_SOCK_NODELAY.  The flags are described
       in "FLAGS" below.

       BIO_listen() has sock start listening on the address and service given by addr.  Connection options may
       be zero or any combination of BIO_SOCK_KEEPALIVE, BIO_SOCK_NONBLOCK, BIO_SOCK_NODELAY, BIO_SOCK_REUSEADDR
       and BIO_SOCK_V6_ONLY.  The flags are described in "FLAGS" below.

       BIO_accept_ex() waits for an incoming connections on the given socket accept_sock.  When it gets a
       connection, the address and port of the peer gets stored in peer if that one is non-NULL.  Accept options
       may be zero or BIO_SOCK_NONBLOCK, and is applied on the accepted socket.  The flags are described in
       "FLAGS" below.

       BIO_closesocket() closes sock.

FLAGS

       BIO_SOCK_KEEPALIVE
           Enables regular sending of keep-alive messages.

       BIO_SOCK_NONBLOCK
           Sets the socket to non-blocking mode.

       BIO_SOCK_NODELAY
           Corresponds to 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.

       BIO_SOCK_REUSEADDR
           Try to reuse the address and port combination for a recently closed port.

       BIO_SOCK_V6_ONLY
           When creating an IPv6 socket, make it only listen for IPv6 addresses and not IPv4 addresses mapped to
           IPv6.

       These flags are bit flags, so they are to be combined with the "|" operator, for example:

        BIO_connect(sock, addr, BIO_SOCK_KEEPALIVE | BIO_SOCK_NONBLOCK);

RETURN VALUES

       BIO_socket() returns the socket number on success or 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 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.

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.

SEE ALSO

       BIO_ADDR(3)

COPYRIGHT

       Copyright 2016-2018 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
       <https://www.openssl.org/source/license.html>.