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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <meta name="description" content="LuaSocket: DNS support"> <meta name="keywords" content="Lua, LuaSocket, DNS, Network, Library, Support"> <title>LuaSocket: DNS support</title> <link rel="stylesheet" href="reference.css" type="text/css"> </head> <body> <!-- header +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --> <div class="header"> <hr> <center> <table summary="LuaSocket logo"> <tr><td align="center"><a href="http://www.lua.org"> <img width="128" height="128" border="0" alt="LuaSocket" src="luasocket.png"> </a></td></tr> <tr><td align="center" valign="top">Network support for the Lua language </td></tr> </table> <p class="bar"> <a href="index.html">home</a> · <a href="index.html#download">download</a> · <a href="installation.html">installation</a> · <a href="introduction.html">introduction</a> · <a href="reference.html">reference</a> </p> </center> <hr> </div> <!-- dns ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --> <h2 id="dns">DNS</h2> <p> IPv4 name resolution functions <a href="#toip"><tt>dns.toip</tt></a> and <a href="#tohostname"><tt>dns.tohostname</tt></a> return <em>all</em> information obtained from the resolver in a table of the form: </p> <blockquote><tt> resolved4 = {<br> name = <i>canonic-name</i>,<br> alias = <i>alias-list</i>,<br> ip = <i>ip-address-list</i><br> } </tt> </blockquote> <p> Note that the <tt>alias</tt> list can be empty. </p> <p> The more general name resolution function <a href="#getaddrinfo"><tt>dns.getaddrinfo</tt></a>, which supports both IPv6 and IPv4, returns <em>all</em> information obtained from the resolver in a table of the form: </p> <blockquote><tt> resolved6 = {<br> [1] = {<br> family = <i>family-name-1</i>,<br> addr = <i>address-1</i><br> },<br> ...<br> [n] = {<br> family = <i>family-name-n</i>,<br> addr = <i>address-n</i><br> }<br> } </tt> </blockquote> <p> Here, <tt>family</tt> contains the string <tt>"inet"</tt> for IPv4 addresses, and <tt>"inet6"</tt> for IPv6 addresses. </p> <!-- getaddrinfo ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --> <p class="name" id="getaddrinfo"> socket.dns.<b>getaddrinfo(</b>address<b>)</b> </p> <p class="description"> Converts from host name to address. </p> <p class="parameters"> <tt>Address</tt> can be an IPv4 or IPv6 address or host name. </p> <p class="return"> The function returns a table with all information returned by the resolver. In case of error, the function returns <b><tt>nil</tt></b> followed by an error message. </p> <!-- gethostname ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --> <p class="name" id="gethostname"> socket.dns.<b>gethostname()</b> </p> <p class="description"> Returns the standard host name for the machine as a string. </p> <!-- tohostname +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --> <p class="name" id="tohostname"> socket.dns.<b>tohostname(</b>address<b>)</b> </p> <p class="description"> Converts from IPv4 address to host name. </p> <p class="parameters"> <tt>Address</tt> can be an IP address or host name. </p> <p class="return"> The function returns a string with the canonic host name of the given <tt>address</tt>, followed by a table with all information returned by the resolver. In case of error, the function returns <b><tt>nil</tt></b> followed by an error message. </p> <!-- toip +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --> <p class="name" id="toip"> socket.dns.<b>toip(</b>address<b>)</b> </p> <p class="description"> Converts from host name to IPv4 address. </p> <p class="parameters"> <tt>Address</tt> can be an IP address or host name. </p> <p class="return"> Returns a string with the first IP address found for <tt>address</tt>, followed by a table with all information returned by the resolver. In case of error, the function returns <b><tt>nil</tt></b> followed by an error message. </p> <!-- footer +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ --> <div class="footer"> <hr> <center> <p class="bar"> <a href="index.html">home</a> · <a href="index.html#down">download</a> · <a href="installation.html">installation</a> · <a href="introduction.html">introduction</a> · <a href="reference.html">reference</a> </p> <p> <small> Last modified by Diego Nehab on <br> Thu Apr 20 00:25:07 EDT 2006 </small> </p> </center> </div> </body> </html>