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=pod

=head1 NAME

SSL_set_bio, SSL_set0_rbio, SSL_set0_wbio - connect the SSL object with a BIO

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 void SSL_set_bio(SSL *ssl, BIO *rbio, BIO *wbio);
 void SSL_set0_rbio(SSL *s, BIO *rbio);
 void SSL_set0_wbio(SSL *s, BIO *wbio);

=head1 DESCRIPTION

SSL_set0_rbio() connects the BIO B<rbio> for the read operations of the B<ssl>
object. The SSL engine inherits the behaviour of B<rbio>. If the BIO is
nonblocking then the B<ssl> object will also have nonblocking behaviour. This
function transfers ownership of B<rbio> to B<ssl>. It will be automatically
freed using L<BIO_free_all(3)> when the B<ssl> is freed. On calling this
function, any existing B<rbio> that was previously set will also be freed via a
call to L<BIO_free_all(3)> (this includes the case where the B<rbio> is set to
the same value as previously).

SSL_set0_wbio() works in the same as SSL_set0_rbio() except that it connects
the BIO B<wbio> for the write operations of the B<ssl> object. Note that if the
rbio and wbio are the same then SSL_set0_rbio() and SSL_set0_wbio() each take
ownership of one reference. Therefore, it may be necessary to increment the
number of references available using L<BIO_up_ref(3)> before calling the set0
functions.

SSL_set_bio() is similar to SSL_set0_rbio() and SSL_set0_wbio() except
that it connects both the B<rbio> and the B<wbio> at the same time, and
transfers the ownership of B<rbio> and B<wbio> to B<ssl> according to
the following set of rules:

=over 2

=item *

If neither the B<rbio> or B<wbio> have changed from their previous values
then nothing is done.

=item *

If the B<rbio> and B<wbio> parameters are different and both are different
to their
previously set values then one reference is consumed for the rbio and one
reference is consumed for the wbio.

=item *

If the B<rbio> and B<wbio> parameters are the same and the B<rbio> is not
the same as the previously set value then one reference is consumed.

=item *

If the B<rbio> and B<wbio> parameters are the same and the B<rbio> is the
same as the previously set value, then no additional references are consumed.

=item *

If the B<rbio> and B<wbio> parameters are different and the B<rbio> is the
same as the
previously set value then one reference is consumed for the B<wbio> and no
references are consumed for the B<rbio>.

=item *

If the B<rbio> and B<wbio> parameters are different and the B<wbio> is the
same as the previously set value and the old B<rbio> and B<wbio> values
were the same as each other then one reference is consumed for the B<rbio>
and no references are consumed for the B<wbio>.

=item *

If the B<rbio> and B<wbio> parameters are different and the B<wbio>
is the same as the
previously set value and the old B<rbio> and B<wbio> values were different
to each
other then one reference is consumed for the B<rbio> and one reference
is consumed
for the B<wbio>.

=back

Because of this complexity, this function should be avoided;
use SSL_set0_rbio() and SSL_set0_wbio() instead.

=head1 RETURN VALUES

SSL_set_bio(), SSL_set0_rbio() and SSL_set0_wbio() cannot fail.

=head1 SEE ALSO

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

=head1 HISTORY

SSL_set0_rbio() and SSL_set0_wbio() were added in OpenSSL 1.1.0.

=head1 COPYRIGHT

Copyright 2000-2020 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