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+=pod
+
+=head1 NAME
+
+SSL_do_handshake - perform a TLS/SSL handshake
+
+=head1 SYNOPSIS
+
+ #include <openssl/ssl.h>
+
+ int SSL_do_handshake(SSL *ssl);
+
+=head1 DESCRIPTION
+
+SSL_do_handshake() will wait for a SSL/TLS handshake to take place. If the
+connection is in client mode, the handshake will be started. The handshake
+routines may have to be explicitly set in advance using either
+L<SSL_set_connect_state(3)|SSL_set_connect_state(3)> or
+L<SSL_set_accept_state(3)|SSL_set_accept_state(3)>.
+
+=head1 NOTES
+
+The behaviour of SSL_do_handshake() depends on the underlying BIO.
+
+If the underlying BIO is B<blocking>, SSL_do_handshake() will only return
+once the handshake has been finished or an error occurred, except for SGC
+(Server Gated Cryptography). For SGC, SSL_do_handshake() may return with -1,
+but SSL_get_error() will yield B<SSL_ERROR_WANT_READ/WRITE> and
+SSL_do_handshake() should be called again.
+
+If the underlying BIO is B<non-blocking>, SSL_do_handshake() will also return
+when the underlying BIO could not satisfy the needs of SSL_do_handshake()
+to continue the handshake. In this case a call to SSL_get_error() with the
+return value of SSL_do_handshake() 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_do_handshake().
+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 TLS/SSL handshake was successfully completed, a TLS/SSL connection has been
+established.
+
+=item 0
+
+The TLS/SSL handshake was not successful but was shut down controlled and
+by the specifications of the TLS/SSL protocol. Call SSL_get_error() with the
+return value B<ret> to find out the reason.
+
+=item E<lt>0
+
+The TLS/SSL handshake was not successful because a fatal error occurred either
+at the protocol level or a connection failure occurred. The shutdown was
+not clean. 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)>,
+L<SSL_set_connect_state(3)|SSL_set_connect_state(3)>
+
+=cut