ngtcp2_conn_get_active_dcid
===========================

Synopsis
--------

*#include <ngtcp2/ngtcp2.h>*

.. function:: size_t ngtcp2_conn_get_active_dcid(ngtcp2_conn *conn, ngtcp2_cid_token *dest)

    
    `ngtcp2_conn_get_active_dcid` writes the all active Destination
    Connection IDs and their tokens to *dest*.  Before handshake
    completes, this function returns 0.  If *dest* is NULL, this
    function does not write anything, and returns the number of
    Destination Connection IDs that would otherwise be written to the
    provided buffer.  The buffer pointed by *dest* must have
    sizeof(:type:`ngtcp2_cid_token`) * n bytes available, where n is
    the return value of `ngtcp2_conn_get_active_dcid` with *dest* ==
    NULL.