=pod

=head1 NAME

SSL_set_fd, SSL_set_rfd, SSL_set_wfd - connect the SSL object with a file descriptor

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 int SSL_set_fd(SSL *ssl, int fd);
 int SSL_set_rfd(SSL *ssl, int fd);
 int SSL_set_wfd(SSL *ssl, int fd);

=head1 DESCRIPTION

SSL_set_fd() sets the file descriptor B<fd> as the input/output facility
for the TLS/SSL (encrypted) side of B<ssl>. B<fd> will typically be the
socket file descriptor of a network connection.

When performing the operation, a B<socket BIO> is automatically created to
interface between the B<ssl> and B<fd>. The BIO and hence the SSL engine
inherit the behaviour of B<fd>. If B<fd> is nonblocking, the B<ssl> will
also have nonblocking behaviour.

If there was already a BIO connected to B<ssl>, BIO_free() will be called
(for both the reading and writing side, if different).

SSL_set_rfd() and SSL_set_wfd() perform the respective action, but only
for the read channel or the write channel, which can be set independently.

=head1 RETURN VALUES

The following return values can occur:

=over 4

=item Z<>0

The operation failed. Check the error stack to find out why.

=item Z<>1

The operation succeeded.

=back

=head1 NOTES

On Windows, a socket handle is a 64-bit data type (UINT_PTR), which leads to a
compiler warning (conversion from 'SOCKET' to 'int', possible loss of data) when
passing the socket handle to SSL_set_*fd(). For the time being, this warning can
safely be ignored, because although the Microsoft documentation claims that the
upper limit is INVALID_SOCKET-1 (2^64 - 2), in practice the current socket()
implementation returns an index into the kernel handle table, the size of which
is limited to 2^24.


=head1 SEE ALSO

L<SSL_get_fd(3)>, L<SSL_set_bio(3)>,
L<SSL_connect(3)>, L<SSL_accept(3)>,
L<SSL_shutdown(3)>, L<ssl(7)> , L<bio(7)>

=head1 COPYRIGHT

Copyright 2000-2021 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
