d. The function does the basic checks of the IP header such as packet size being at least larger than the header size etc. If the packet was not destined for us, the packet is forwarded (using ip_forward). The IP checksum is always checked.</p>
<p>Finally, the packet is sent to the upper layer protocol input function.</p>
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramname">p</td><td>the received IP packet (p-&gt;payload points to IP header) </td></tr>
    <tr><t