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&lt;!-- dns ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --&gt;

&lt;h2 id=&quot;dns&quot;&gt;DNS&lt;/h2&gt;

&lt;p&gt;
IPv4 name resolution functions
&lt;a href=&quot;#toip&quot;&gt;&lt;tt&gt;dns.toip&lt;/tt&gt;&lt;/a&gt;
and
&lt;a href=&quot;#tohostname&quot;&gt;&lt;tt&gt;dns.tohostname&lt;/tt&gt;&lt;/a&gt;
return &lt;em&gt;all&lt;/em&gt; information obtained from
the resolver in a table of the form:
&lt;/p&gt;

&lt;blockquote&gt;&lt;tt&gt;
resolved4 = {&lt;br&gt;
&amp;nbsp;&amp;nbsp;name = &lt;i&gt;canonic-name&lt;/i&gt;,&lt;br&gt;
&amp;nbsp;&amp;nbsp;alias = &lt;i&gt;alias-list&lt;/i&gt;,&lt;br&gt;
&amp;nbsp;&amp;nbsp;ip = &lt;i&gt;ip-address-list&lt;/i&gt;&lt;br&gt;
}
&lt;/tt&gt; &lt;/blockquote&gt;

&lt;p&gt;
Note that the &lt;tt&gt;alias&lt;/tt&gt; list can be empty.
&lt;/p&gt;

&lt;p&gt;
The more general name resolution function
&lt;a href=&quot;#getaddrinfo&quot;&gt;&lt;tt&gt;dns.getaddrinfo&lt;/tt&gt;&lt;/a&gt;, which
supports both IPv6 and IPv4,
returns &lt;em&gt;all&lt;/em&gt; information obtained from
the resolver in a table of the form:
&lt;/p&gt;

&lt;blockquote&gt;&lt;tt&gt;
resolved6 = {&lt;br&gt;
&amp;nbsp;&amp;nbsp;[1] = {&lt;br&gt;
&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;family = &lt;i&gt;family-name-1&lt;/i&gt;,&lt;br&gt;
&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;addr = &lt;i&gt;address-1&lt;/i&gt;&lt;br&gt;
&amp;nbsp;&amp;nbsp;},&lt;br&gt;
&amp;nbsp;&amp;nbsp;...&lt;br&gt;
&amp;nbsp;&amp;nbsp;[n] = {&lt;br&gt;
&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;family = &lt;i&gt;family-name-n&lt;/i&gt;,&lt;br&gt;
&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;addr = &lt;i&gt;address-n&lt;/i&gt;&lt;br&gt;
&amp;nbsp;&amp;nbsp;}&lt;br&gt;
}
&lt;/tt&gt; &lt;/blockquote&gt;

&lt;p&gt;
Here, &lt;tt&gt;family&lt;/tt&gt; contains the string &lt;tt&gt;&quot;inet&quot;&lt;/tt&gt; for IPv4
addresses, and &lt;tt&gt;&quot;inet6&quot;&lt;/tt&gt; for IPv6 addresses.
&lt;/p&gt;

&lt;!-- getaddrinfo ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --&gt;

&lt;p class=&quot;name&quot; id=&quot;getaddrinfo&quot;&gt;
socket.dns.&lt;b&gt;getaddrinfo(&lt;/b&gt;address&lt;b&gt;)&lt;/b&gt;
&lt;/p&gt;

&lt;p class=&quot;description&quot;&gt;
Converts from host name to address.
&lt;/p&gt;

&lt;p class=&quot;parameters&quot;&gt;
&lt;tt&gt;Address&lt;/tt&gt; can  be an IPv4 or IPv6 address or host name.
&lt;/p&gt;

&lt;p class=&quot;return&quot;&gt;
The function returns a table with  all  information returned  by
the  resolver.  In  case of error, the function returns &lt;b&gt;&lt;tt&gt;nil&lt;/tt&gt;&lt;/b&gt;
followed by an error message.
&lt;/p&gt;

&lt;!-- gethostname ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --&gt;

&lt;p class=&quot;name&quot; id=&quot;gethostname&quot;&gt;
socket.dns.&lt;b&gt;gethostname()&lt;/b&gt;
&lt;/p&gt;

&lt;p class=&quot;description&quot;&gt;
Returns the standard host name for the machine as a string.
&lt;/p&gt;

&lt;!-- tohostname +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --&gt;

&lt;p class=&quot;name&quot; id=&quot;tohostname&quot;&gt;
socket.dns.&lt;b&gt;tohostname(&lt;/b&gt;address&lt;b&gt;)&lt;/b&gt;
&lt;/p&gt;

&lt;p class=&quot;description&quot;&gt;
Converts from IPv4 address to host name.
&lt;/p&gt;

&lt;p class=&quot;parameters&quot;&gt;
&lt;tt&gt;Address&lt;/tt&gt; can  be an IP address  or host name.
&lt;/p&gt;

&lt;p class=&quot;return&quot;&gt;
The function returns a string  with the canonic host name of the given
&lt;tt&gt;address&lt;/tt&gt;, followed  by a  table with  all  information returned  by
the  resolver.  In  case of error, the function returns &lt;b&gt;&lt;tt&gt;nil&lt;/tt&gt;&lt;/b&gt;
followed by an error message.
&lt;/p&gt;

&lt;!-- toip +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --&gt;

&lt;p class=&quot;name&quot; id=&quot;toip&quot;&gt;
socket.dns.&lt;b&gt;toip(&lt;/b&gt;address&lt;b&gt;)&lt;/b&gt;
&lt;/p&gt;

&lt;p class=&quot;description&quot;&gt;
Converts from host name to IPv4 address.
&lt;/p&gt;

&lt;p class=&quot;parameters&quot;&gt;
&lt;tt&gt;Address&lt;/tt&gt; can  be an IP address  or host name.
&lt;/p&gt;

&lt;p class=&quot;return&quot;&gt;
Returns a string  with the first IP address  found for &lt;tt&gt;address&lt;/tt&gt;,
followed  by a  table with  all  information returned  by the  resolver.
In  case of error, the function returns &lt;b&gt;&lt;tt&gt;nil&lt;/tt&gt;&lt;/b&gt; followed by an error
message.
&lt;/p&gt;

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&lt;small&gt;
Last modified by Diego Nehab on &lt;br&gt;
Thu Apr 20 00:25:07 EDT 2006
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