of the message's sequence number.
Due to the unreliable nature of the protocol, this field allows
distinguishing out-of-order messages.

 -- Function: ssize_t gnutls_record_recv_seq (gnutls_session_t SESSION,
          void * DATA, size_t DATA_SIZE, unsigned char * SEQ)
     SESSION: is a ‘gnutls_session_t’ type.

     DATA: the buffer that the data will be read into

     DATA_SIZE: the number of requested bytes

     SEQ: is the packet's 64-bit sequence number.  Should have space for
     8 bytes.

     This function is the same as ‘gnutls_record_recv()’ , except that
     it returns in addition to data, the sequence number of the data.
     This is useful in DTLS where record packets might be received
     out-of-order.  The returned 8-byte sequence number is an integer in
     big-endian format and should be treated as a unique message
     identification.

     *Returns:* The number of bytes received and zero on EOF. A negative
     error code is returned in case of an error.  The number of bytes
     received might be less than ‘data_size’ .

     *Since:* 3.0

The *note gnutls_record_check_pending:: helper function is available to
allow checking whether data are available to be read in a GnuTLS session
buffers.  Note that this function complements but does not replace
‘poll’, i.e., *note gnutls_record_check_pending:: reports no data to be
read, ‘poll’ should be called to check for data in the network buffers.

 -- Function: size_t gnutls_record_check_pending (gnutls_session_t
          SESSION)
     SESSION: is a ‘gnutls_session_t’ type.

     This function checks if there are unread data in the gnutls
     buffers.  If the return value is non-zero the next call to
     ‘gnutls_record_recv()’ is guaranteed not to block.

     *Returns:* Returns the size of the data or zero.
‘INT *note gnutls_record_get_direction:: (gnutls_session_t SESSION)’

Once a TLS or DTLS session is no longer needed, it is recommended to use
*note gnutls_bye:: to terminate the session.  That way the peer is
notified securely about the intention of termination, which allows
distinguishing it from a malicious connection termination.  A session
can be deinitialized with the *note gnutls_deinit:: function.

 -- Function: int gnutls_bye (gnutls_session_t SESSION,
          gnutls_close_request_t HOW)
     SESSION: is a ‘gnutls_session_t’ type.

     HOW: is an integer

     Terminates the current TLS/SSL connection.  The connection should
     have been initiated using ‘gnutls_handshake()’ .  ‘how’ should be
     one of ‘GNUTLS_SHUT_RDWR’ , ‘GNUTLS_SHUT_WR’ .

     In case of ‘GNUTLS_SHUT_RDWR’ the TLS session gets terminated and
     further receives and sends will be disallowed.  If the return value
     is zero you may continue using the underlying transport layer.
     ‘GNUTLS_SHUT_RDWR’ sends an alert containing a close request and
     waits for the peer to reply with the same message.

     In case of ‘GNUTLS_SHUT_WR’ the TLS session gets terminated and
     further sends will be disallowed.  In order to reuse the connection
     you should wait for an EOF from the peer.  ‘GNUTLS_SHUT_WR’ sends
     an alert containing a close request.

     Note that not all implementations will properly terminate a TLS
     connection.  Some of them, usually for performance reasons, will
     terminate only the underlying transport layer, and thus not
     distinguishing between a malicious party prematurely terminating
     the connection and normal termination.

     This function may also return ‘GNUTLS_E_AGAIN’ or
     ‘GNUTLS_E_INTERRUPTED’ ; cf.  ‘gnutls_record_get_direction()’ .

     *Returns:* ‘GNUTLS_E_SUCCESS’ on success, or an error code, see
     function documentation for entire semantics.

 -- Function: void gnutls_deinit (gnutls_session_t SESSION)
     SESSION: is a ‘gnutls_session_t’ type.

     This function clears all buffers associated with the ‘session’ .
     This function will also remove session data from the session
     database if the session was terminated abnormally.