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=pod
=head1 NAME
SSL_shutdown - shut down a TLS/SSL connection
=head1 SYNOPSIS
#include <openssl/ssl.h>
int SSL_shutdown(SSL *ssl);
=head1 DESCRIPTION
SSL_shutdown() shuts down an active TLS/SSL connection. It sends the shutdown
alert to the peer. The behaviour of SSL_shutdown() depends on the underlying
BIO.
If the underlying BIO is B<blocking>, SSL_shutdown() will only return once the
handshake has been finished or an error occurred.
If the underlying BIO is B<non-blocking>, SSL_shutdown() will also return
when the underlying BIO could not satisfy the needs of SSL_shutdown()
to continue the handshake. In this case a call to SSL_get_error() with the
return value of SSL_shutdown() will yield B<SSL_ERROR_WANT_READ> or
B<SSL_ERROR_WANT_WRITE>. The calling process then must repeat the call after
taking appropriate action to satisfy the needs of SSL_shutdown().
The action depends on the underlying BIO. When using a non-blocking socket,
nothing is to be done, but select() can be used to check for the required
condition. When using a buffering BIO, like a BIO pair, data must be written
into or retrieved out of the BIO before being able to continue.
=head1 RETURN VALUES
The following return values can occur:
=over 4
=item 1
The shutdown was successfully completed.
=item 0
The shutdown was not successful. Call SSL_get_error() with the return
value B<ret> to find out the reason.
=item -1
The shutdown was not successful because a fatal error occurred either
at the protocol level or a connection failure occurred. It can also occur of
action is need to continue the operation for non-blocking BIOs.
Call SSL_get_error() with the return value B<ret> to find out the reason.
=back
=head1 SEE ALSO
L<SSL_get_error(3)|SSL_get_error(3)>, L<SSL_connect(3)|SSL_connect(3)>,
L<SSL_accept(3)|SSL_accept(3)>, L<ssl(3)|ssl(3)>, L<bio(3)|bio(3)>
=cut
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