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_REUSEADDR, 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 nonblocking 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.

SEE ALSO

       BIO_ADDR(3)

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.

COPYRIGHT

       Copyright 2016-2020 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.