direct send: these segments don't contain data but control the connection behaviour. They are created as pbuf only and sent directly without enqueueing them:<ul>
<li><a class="el" href="tcp__priv_8h.html#aefde3e34b2cc8df9654986484c44a996">tcp_send_empty_ack</a> sends an ACK-only segment</li>
<li><a class="el" href="tcp__priv_8h.html#aa90f8051c9633d3017c588245cdc4014">tcp_rst</a> sends a RST segment</li>
<li><a class="el" href="tcp__priv_8h.html#a0d8bb5fc8522515aa35d305774cc5332">tcp_keepalive</a> sends a ke