long dtls1_ctrl(SSL *s, int cmd, long larg, void *parg)
{
    int ret = 0;

    switch (cmd) {
    case DTLS_CTRL_GET_TIMEOUT:
        if (dtls1_get_timeout(s, (struct timeval *)parg) != NULL) {
            ret = 1;
        }
        break;
    case DTLS_CTRL_HANDLE_TIMEOUT:
        ret = dtls1_handle_timeout(s);
        break;
    case DTLS_CTRL_LISTEN:
        ret = dtls1_listen(s, parg);
        break;
    case SSL_CTRL_CHECK_PROTO_VERSION:
        /*
         * For library-internal use; checks that the current protocol is the
         * highest enabled version (according to s->ctx->method, as version
         * negotiation may have changed s->method).
         */
        if (s->version == s->ctx->method->version)
            return 1;
        /*
         * Apparently we're using a version-flexible SSL_METHOD (not at its
         * highest protocol version).
         */
        if (s->ctx->method->version == DTLS_method()->version) {
#if DTLS_MAX_VERSION != DTLS1_2_VERSION
# error Code needs update for DTLS_method() support beyond DTLS1_2_VERSION.
#endif
            if (!(s->options & SSL_OP_NO_DTLSv1_2))
                return s->version == DTLS1_2_VERSION;
            if (!(s->options & SSL_OP_NO_DTLSv1))
                return s->version == DTLS1_VERSION;
        }
        return 0;               /* Unexpected state; fail closed. */
    case DTLS_CTRL_SET_LINK_MTU:
        if (larg < (long)dtls1_link_min_mtu())
            return 0;
        s->d1->link_mtu = larg;
        return 1;
    case DTLS_CTRL_GET_LINK_MIN_MTU:
        return (long)dtls1_link_min_mtu();
    case SSL_CTRL_SET_MTU:
        /*
         *  We may not have a BIO set yet so can't call dtls1_min_mtu()
         *  We'll have to make do with dtls1_link_min_mtu() and max overhead
         */
        if (larg < (long)dtls1_link_min_mtu() - DTLS1_MAX_MTU_OVERHEAD)
            return 0;
        s->d1->mtu = larg;
        return larg;
    default:
        ret = ssl3_ctrl(s, cmd, larg, parg);
        break;
    }
    return (ret);
}

Unknown