mirror of
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519 lines
17 KiB
HTML
519 lines
17 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
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"http://www.w3.org/TR/html4/strict.dtd">
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<html>
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<head>
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<meta name="description" content="LuaSocket: The TCP/IP support">
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<meta name="keywords" content="Lua, Library, socket, TCP, Network, Support">
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<title>LuaSocket: TCP/IP support</title>
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<link rel="stylesheet" href="reference.css" type="text/css">
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</head>
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<body>
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<!-- header +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<div class=header>
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<hr>
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<center>
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<table summary="LuaSocket logo">
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<tr><td align=center><a href="http://www.lua.org">
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<img width=128 height=128 border=0 alt="LuaSocket" src="luasocket.png">
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</a></td></tr>
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<tr><td align=center valign=top>Network support for the Lua language
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</td></tr>
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</table>
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<p class=bar>
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<a href="home.html">home</a> ·
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<a href="home.html#download">download</a> ·
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<a href="introduction.html">introduction</a> ·
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<a href="reference.html">reference</a>
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</p>
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</center>
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<hr>
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</div>
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<!-- tcp ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<h2 id=tcp>TCP</h2>
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<!-- socket.tcp +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=socket.tcp>
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socket.<b>tcp()</b>
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</p>
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<p class=description>
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Creates and returns a TCP master object. A master object can
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be transformed into a server object with the method
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<a href=#listen><tt>listen</tt></a> (after a call to <a
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href=#bind><tt>bind</tt></a>) or into a client object with
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the method <a href=#connect><tt>connect</tt></a>. The only other
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method supported by a master object is the
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<a href=#close><tt>close</tt></a> method.</p>
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<p class=return>
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In case of success, a new master object is returned. In case of error,
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<b><tt>nil</tt></b> is returned, followed by an error message.
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</p>
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<!-- accept +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=accept>
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server:<b>accept()</b>
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</p>
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<p class=description>
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Waits for a remote connection on the server
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object and returns a client object representing that connection.
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</p>
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<p class=return>
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If a connection is successfully initiated, a client object is returned.
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If a timeout condition is met, the method returns <b><tt>nil</tt></b>
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followed by the error string '<tt>timeout</tt>'. Other errors are
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reported by <b><tt>nil</tt></b> followed by a message describing the error.
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</p>
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<p class=note>
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Note: calling <a href=socket.html#select><tt>socket.select</tt></a>
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with a server object in
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the <tt>receive</tt> parameter before a call to <tt>accept</tt> does
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<em>not</em> guarantee <tt>accept</tt> will return immediately. Use the <a
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href=#settimeout><tt>settimeout</tt></a> method or <tt>accept</tt>
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might block until <em>another</em> client shows up.
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</p>
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<!-- bind +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=bind>
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master:<b>bind(</b>address, port<b>)</b>
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</p>
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<p class=description>
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Binds a master object to <tt>address</tt> and <tt>port</tt> on the
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local host.
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<p class=parameters>
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<tt>Address</tt> can be an IP address or a host name.
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<tt>Port</tt> must be an integer number in the range [0..64K).
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If <tt>address</tt>
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is '<tt>*</tt>', the system binds to all local interfaces
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using the <tt>INADDR_ANY</tt> constant. If <tt>port</tt> is 0, the system automatically
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chooses an ephemeral port.
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</p>
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<p class=return>
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In case of success, the method returns 1. In case of error, the
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method returns <b><tt>nil</tt></b> followed by an error message.
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</p>
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<p class=note>
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Note: The function <a href=socket.html#bind><tt>socket.bind</tt></a>
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is available and is a shortcut for the creation server sockets.
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</p>
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<!-- close ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=close>
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master:<b>close()</b><br>
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client:<b>close()</b><br>
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server:<b>close()</b>
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</p>
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<p class=description>
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Closes a TCP object. The internal socket used by the object is closed
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and the local address to which the object was
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bound is made available to other applications. No further operations
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(except for further calls to the <tt>close</tt> method) are allowed on
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a closed socket.
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</p>
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<p class=note>
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Note: It is important to close all used sockets once they are not
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needed, since, in many systems, each socket uses a file descriptor,
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which are limited system resources. Garbage-collected objects are
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automatically closed before destruction, though.
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</p>
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<!-- connect ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=connect>
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master:<b>connect(</b>address, port<b>)</b>
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</p>
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<p class=description>
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Attempts to connect a master object to a remote host, transforming it into a
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client object.
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Client objects support methods
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<a href=#send><tt>send</tt></a>,
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<a href=#receive><tt>receive</tt></a>,
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<a href=#getsockname><tt>getsockname</tt></a>,
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<a href=#getpeername><tt>getpeername</tt></a>,
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<a href=#settimeout><tt>settimeout</tt></a>,
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and <a href=#close><tt>close</tt></a>.
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</p>
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<p class=parameters>
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<tt>Address</tt> can be an IP address or a host name.
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<tt>Port</tt> must be an integer number in the range [1..64K).
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</p>
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<p class=return>
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In case of error, the method returns <b><tt>nil</tt></b> followed by a string
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describing the error. In case of success, the method returns 1.
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</p>
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<p class=note>
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Note: The function <a href=socket.html#connect><tt>socket.connect</tt></a>
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is available and is a shortcut for the creation of client sockets.
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</p>
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<p class=note>
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Note: Starting with LuaSocket 2.0,
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the <a href=#settimeout><tt>settimeout</tt></a>
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method affects the behavior of connect, causing it to return in case of
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a timeout.
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</p>
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<!-- getpeername ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=getpeername>
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client:<b>getpeername()</b>
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</p>
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<p class=description>
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Returns information about the remote side of a connected client object.
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</p>
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<p class=return>
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Returns a string with the IP address of the peer, followed by the
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port number that peer is using for the connection.
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In case of error, the method returns <b><tt>nil</tt></b>.
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</p>
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<p class=note>
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Note: It makes no sense to call this method on server objects.
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</p>
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<!-- getsockname ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=getsockname>
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master:<b>getsockname()</b><br>
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client:<b>getsockname()</b><br>
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server:<b>getsockname()</b>
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</p>
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<p class=description>
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Returns the local address information associated to the object.
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</p>
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<p class=return>
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The method returns a string with local IP address and a number with
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the port. In case of error, the method returns <b><tt>nil</tt></b>.
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</p>
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<!-- getsockname ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=getstats>
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client:<b>getstats()</b><br>
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</p>
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<p class=description>
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Returns accounting information on the socket, useful for throttling
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of bandwidth.
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</p>
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<p class=return>
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The method returns the number of bytes received, the number of bytes sent,
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and the age of the socket object in seconds.
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</p>
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<!-- listen ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=listen>
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master:<b>listen(</b>backlog<b>)</b>
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</p>
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<p class=description>
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Specifies the socket is willing to receive connections, transforming the
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object into a server object. Server objects support the
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<a href=#accept><tt>accept</tt></a>,
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<a href=#getsockname><tt>getsockname</tt></a>,
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<a href=#setoption><tt>setoption</tt></a>,
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<a href=#settimeout><tt>settimeout</tt></a>,
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and <a href=#close><tt>close</tt></a> methods.
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</p>
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<p class=parameters>
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The parameter <tt>backlog</tt> specifies the number of client
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connections that can
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be queued waiting for service. If the queue is full and another client
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attempts connection, the connection is refused.
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</p>
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<p class=return>
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In case of success, the method returns 1. In case of error, the
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method returns <b><tt>nil</tt></b> followed by an error message.
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</p>
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<!-- receive ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=receive>
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client:<b>receive(</b>[pattern [, prefix]]<b>)</b>
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</p>
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<p class=description>
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Reads data from a client object, according to the specified <em>read
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pattern</em>. Patterns follow the Lua file I/O format, and the difference in performance between all patterns is negligible.
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</p>
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<p class=parameters>
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<tt>Pattern</tt> can be any of the following:
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</p>
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<ul>
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<li> '<tt>*a</tt>': reads from the socket until the connection is
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closed. No end-of-line translation is performed;
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<li> '<tt>*l</tt>': reads a line of text from the socket. The line is
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terminated by a LF character (ASCII 10), optionally preceded by a
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CR character (ASCII 13). The CR and LF characters are not included in
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the returned line. This is the default pattern;
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<li> <tt>number</tt>: causes the method to read a specified <tt>number</tt>
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of bytes from the socket.
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</ul>
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<p class=parameters>
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<tt>Prefix</tt> is an optional string to be concatenated to the beginning
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of any received data before return.
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</p>
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<p class=return>
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If successful, the method returns the received pattern. In case of error,
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the method returns <tt><b>nil</b></tt> followed by an error message which
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can be the string '<tt>closed</tt>' in case the connection was
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closed before the transmission was completed or the string
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'<tt>timeout</tt>' in case there was a timeout during the operation.
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Also, after the error message, the function returns the partial result of
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the transmission.
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</p>
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<p class=note>
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<b>Important note</b>: This function was changed <em>severely</em>. It used
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to support multiple patterns (but I have never seen this feature used) and
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now it doesn't anymore. Partial results used to be returned in the same
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way as successful results. This last feature violated the idea that all
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functions should return <tt><b>nil</b></tt> on error. Thus it was changed
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too.
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</p>
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<!-- send +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=send>
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client:<b>send(</b>data [, i [, j]]<b>)</b>
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</p>
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<p class=description>
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Sends <tt>data</tt> through client object.
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</p>
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<p class=parameters>
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<tt>Data</tt> is the string to be sent. The optional arguments
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<tt>i</tt> and <tt>j</tt> work exactly like the standard
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<tt>string.sub</tt> Lua function to allow the selection of a
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substring to be sent.
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</p>
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<p class=return>
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If successful, the method returns the number of bytes accepted by
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the transport layer. In case of error, the method returns
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<b><tt>nil</tt></b>, followed by an error message, followed by the
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partial number of bytes accepted by the transport layer.
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The error message can be '<tt>closed</tt>' in case
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the connection was closed before the transmission was completed or the
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string '<tt>timeout</tt>' in case there was a timeout during the
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operation.
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</p>
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<p class=note>
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<b>Important note</b>:
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The return values for the <tt>send</tt> method have been changed in
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LuaSocket 2.0 alpha <b>and again</b> in the beta (sorry)!
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In previous versions, the method returned only the
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error message. Since returning <b><tt>nil</tt></b> in case of success was
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nonsense, in alpha the first return value became the number of bytes sent.
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Alas, it wasn't returning <tt><b>nil</b></tt> in case of
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error. So it was changed again in beta.
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</p>
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<p class=note>
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<b>Also important</b>:
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In order to better support non-blocking I/O and to discourage
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bad practice, the <tt>send</tt> method now only sends one string
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per call. The other optional arguments allow the user to select
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a substring to be sent in a much more efficient way than
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using <tt>string.sub</tt>.
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</p>
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<p class=note>
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Note: Output is <em>not</em> buffered. For small strings,
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it is always better to concatenate them in Lua
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(with the '<tt>..</tt>' operator) and send the result in one call
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instead of calling the method several times.
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</p>
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<!-- setoption ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=setoption>
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client:<b>setoption(</b>option [, value]<b>)</b><br>
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server:<b>setoption(</b>option [, value]<b>)</b>
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</p>
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<p class=description>
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Sets options for the TCP object. Options are only needed by low-level or
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time-critical applications. You should only modify an option if you
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are sure you need it.
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</p>
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<p class=parameters>
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<tt>Option</tt> is a string with the option name, and <tt>value</tt>
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depends on the option being set:
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<ul>
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<li> '<tt>keepalive</tt>': Setting this option to <tt>true</tt> enables
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the periodic transmission of messages on a connected socket. Should the
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connected party fail to respond to these messages, the connection is
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considered broken and processes using the socket are notified;
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<li> '<tt>linger</tt>': Controls the action taken when unsent data are
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queued on a socket and a close is performed. The value is a table with a
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boolean entry '<tt>on</tt>' and a numeric entry for the time interval
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'<tt>timeout</tt>' in seconds. If the '<tt>on</tt>' field is set to
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<tt>true</tt>, the system will block the process on the close attempt until
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it is able to transmit the data or until '<tt>timeout</tt>' has passed. If
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'<tt>on</tt>' is <tt>false</tt> and a close is issued, the system will
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process the close in a manner that allows the process to continue as
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quickly as possible. I do not advise you to set this to anything other than
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zero;
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<li> '<tt>reuseaddr</tt>': Setting this option indicates that the rules
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used in validating addresses supplied in a call to
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<a href=#bind><tt>bind</tt></a> should allow reuse of local addresses;
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<li> '<tt>tcp-nodelay</tt>': Setting this option to <tt>true</tt>
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disables the Nagle's algorithm for the connection.
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</ul>
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<p class=return>
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The method returns 1 in case of success, or <b><tt>nil</tt></b> otherwise.
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</p>
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<p class=note>
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Note: The descriptions above come from the man pages.
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</p>
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<!-- settimeout +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=settimeout>
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client:<b>settimeout(</b>value [, mode]<b>)</b><br>
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server:<b>settimeout(</b>value [, mode]<b>)</b>
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</p>
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<p class=description>
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Changes the timeout values for the object. By default,
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all I/O operations are blocking. That is, any call to the methods
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<a href=#send><tt>send</tt></a>,
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<a href=#receive><tt>receive</tt></a>, and
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<a href=#accept><tt>accept</tt></a>
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will block indefinitely, until the operation completes. The
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<tt>settimeout</tt> method defines a limit on the amount of time the
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I/O methods can block. When a timeout is set and the specified amount of
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time has elapsed, the affected methods give up and fail with an error code.
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</p>
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<p class=parameters>
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The amount of time to wait is specified as the
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<tt>value</tt> parameter, in seconds. There are two timeout modes and
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both can be used together for fine tuning:
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</p>
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<ul>
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<li> '<tt>b</tt>': <em>block</em> timeout. Specifies the upper limit on
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the amount of time LuaSocket can be blocked by the operating system
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while waiting for completion of any single I/O operation. This is the
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default mode;</li>
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<li> '<tt>t</tt>': <em>total</em> timeout. Specifies the upper limit on
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the amount of time LuaSocket can block a Lua script before returning from
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a call.</li>
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</ul>
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<p class=parameters>
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The <b><tt>nil</tt></b> timeout <tt>value</tt> allows operations to block
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indefinitely. Negative timeout values have the same effect.
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</p>
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<p class=note>
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Note: although timeout values have millisecond precision in LuaSocket,
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large blocks can cause I/O functions not to respect timeout values due
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to the time the library takes to transfer blocks to and from the OS
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and to and from the Lua interpreter. Also, function that accept host names
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and perform automatic name resolution might be blocked by the resolver for
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longer than the specified timeout value.
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</p>
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<p class=note>
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Note: The old <tt>timeout</tt> method is deprecated. The name has been
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changed for sake of uniformity, since all other method names already
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contained verbs making their imperative nature obvious.
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</p>
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|
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<!-- shutdown +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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|
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<p class=name id=shutdown>
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client:<b>shutdown(</b>mode<b>)</b><br>
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</p>
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<p class=description>
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Shuts down part of a full-duplex connection.
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</p>
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<p class=parameters>
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Mode tells which way of the connection should be shut down and can
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take the value:
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<ul>
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<li>"<tt>both</tt>": disallow further sends and receives on the object.
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This is the default mode;
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<li>"<tt>send</tt>": disallow further sends on the object;
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<li>"<tt>receive</tt>": disallow further receives on the object.
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</ul>
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<p class=return>
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This function returns 1.
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</p>
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<!-- footer +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<div class=footer>
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<hr>
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<center>
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<p class=bar>
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<a href="home.html">home</a> ·
|
|
<a href="home.html#down">download</a> ·
|
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<a href="introduction.html">introduction</a> ·
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<a href="reference.html">reference</a>
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</p>
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<p>
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<small>
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Last modified by Diego Nehab on <br>
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Thu Jun 17 02:47:21 EDT 2004
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</small>
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</p>
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</center>
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</div>
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</body>
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</html>
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