ived (in this case addr is not NULL). &lt; 0 if a transmission error was detected.</li>
<li><cite>buf</cite>: <tt class="docutils literal"><span class="pre">Buffer</span></tt> with the received data.</li>
<li><cite>sockaddr</cite>: struct sockaddr* containing the address of the sender. Can be nil. Valid for the duration of the callback only.</li>
<li><p><cite>flags</cite>: One or more or’ed UDP_* constants. Right now only UDP_PARTIAL is used.</p>
<p>Note: The receive callback will be called with nread == 