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389 lines
12 KiB
HTML
389 lines
12 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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<title>LuaSocket: Network support for the Lua language</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 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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<!-- http +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<h2 id=http>HTTP</h2>
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<p>
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HTTP (Hyper Text Transfer Protocol) is the protocol used to exchange
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information between web-browsers and servers. The <tt>http.lua</tt>
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module offers support for the client side of the HTTP protocol (i.e.,
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the facilities that would be used by a web-browser implementation). The
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implementation conforms to the HTTP/1.1 standard,
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<a href="http://www.cs.princeton.edu/~diego/rfc/rfc2616.txt">RFC
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2616</a>.
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</p>
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<p>
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The module exports functions that provide HTTP functionality in different
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levels of abstraction, from a simple <a
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href="#get"><tt>get</tt></a>, to the generic, stream oriented
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<a href="#request_cb"><tt>request_cb</tt></a>.
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</p>
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<p>
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URLs must conform to
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<a href="http://www.cs.princeton.edu/~diego/rfc/rfc1738.txt">RFC
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1738</a>,
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that is, an URL is a string in the form:
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</p>
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<blockquote>
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<pre>
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[http://][<user>[:<password>]@]<host>[:<port>][/<path>]
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</pre>
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</blockquote>
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<p>
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MIME headers are represented as a Lua table in the form:
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</p>
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<blockquote>
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<table summary="MIME headers in Lua table">
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<tr><td><tt>
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headers = {<br>
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field-1-name = <i>field-1-value</i>,<br>
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field-2-name = <i>field-2-value</i>,<br>
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field-3-name = <i>field-3-value</i>,
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</tt></td></tr>
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<tr><td align=center><tt>
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...
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</tt></td></tr>
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<tr><td><tt>
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field-n-name = <i>field-n-value</i><br>
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}
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</tt></td></tr>
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</table>
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</blockquote>
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<p>
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Field names are case insensitive (as specified by the standard) and all
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functions work with lowercase field names.
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Field values are left unmodified.
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</p>
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<p class=note>
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Note: MIME headers are independent of order. Therefore, there is no problem
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in representing them in a Lua table.
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</p>
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<!-- http.get +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=get>
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socket.http.<b>get(</b>url<b>)</b><br>
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socket.http.<b>get{</b><br>
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url = <i>string</i>,<br>
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headers = <i>header-table</i>,<br>
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user = <i>string</i>,<br>
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password = <i>string</i>,<br>
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stay = <i>bool</i>,<br>
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<b>}</b>
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</p>
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<p class=description>
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Performs the HTTP method <tt>GET</tt>.
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</p>
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<p class=parameters>
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The function can be
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called either directly with a <tt>url</tt> or with a <em>request table</em>.
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The use of a request table allows complete control over the components of
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the request. Values passed explicitly as fields of the request table
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override those given by the <tt>url</tt>. For a description of the fields,
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see the <a href=#request><tt>request</tt></a> function.
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</p>
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<p class=return>
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The function returns the response message body, the mime headers, the
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status code and an error message (if any). In case of failure, the
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function returns all information it managed to gather.
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</p>
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<p class=note>
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Note: The function is trivially implemented with the use of the
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<a href="#request"><tt>request</tt></a> function.
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</p>
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<pre class=example>
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-- connect to server "www.tecgraf.puc-rio.br" and retrieves this manual
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-- file from "/luasocket/http.html"
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b, h, c, e = socket.http.get("http://www.tecgraf.puc-rio.br/luasocket/http.html")
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-- connect to server "www.tecgraf.puc-rio.br" and tries to retrieve
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-- "~diego/auth/index.html". Fails because authentication is needed.
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b, h, c, e = socket.http.get("http://www.tecgraf.puc-rio.br/~diego/auth/index.html")
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-- b returns some useless page telling about the denied access,
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-- h returns authentication information
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-- and c returns with value 401 (Authentication Required)
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-- tries to connect to server "wrong.host" to retrieve "/"
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-- and fails because the host does not exist.
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b, h, c, e = socket.http.get("http://wrong.host/")
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-- b, h, c are nil, and e returns with value "host not found"
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</pre>
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<!-- http.post ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=post>
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socket.http.<b>post(</b>url, body<b>)</b><br>
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socket.http.<b>post{</b><br>
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url = <i>string</i>,<br>
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headers = <i>header-table</i>,<br>
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body = <i>string</i>,<br>
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user = <i>string</i>,<br>
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password = <i>string</i>,<br>
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stay = <i>bool</i>,<br>
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<b>}</b>
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</p>
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<p class=description>
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Same as <a href="#get"><tt>get</tt></a>, except
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that the <tt>POST</tt> method is used and the request
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message <tt>body</tt> is sent along with the request.
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</p>
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<p class=note>
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Note: This function is also trivially implemented with the use of the
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<a href="#request"><tt>request</tt></a> function.
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</p>
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<!-- http.request ++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=request>
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socket.http.<b>request{</b><br>
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method = <i>string</i>,<br>
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url = <i>string</i>,<br>
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headers = <i>header-table</i>,<br>
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body = <i>string</i>,<br>
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user = <i>string</i>,<br>
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password = <i>string</i>,<br>
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stay = <i>string</i>,<br>
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<b>}</b>
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</p>
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<p class=description>
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Performs the generic HTTP request using.
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</p>
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<p class=parameters>
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The request uses <tt>method</tt> on <tt>url</tt>
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sending the request <tt>headers</tt> and request <tt>body</tt> in the
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request message. If authentication information is provided, the function
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uses the Basic Authentication Scheme (see <a href="#authentication">note</a>)
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to retrieve the document. <tt>User</tt> and <tt>password</tt> provided
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explicitly override those given by the <tt>url</tt>. The <tt>stay</tt>
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parameter, when set to anything but <b><tt>nil</tt></b>, prevents the function
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from automatically following 301 or 302 server redirect messages.
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</p>
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<p class=return>
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The function returns a table with all components of the response message
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it managed to retrieve. The response table has the following form:
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</p>
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<blockquote><tt>
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response = {<br>
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body = <i>string</i>,<br>
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headers = <i>header-table</i>,<br>
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status = <i>string</i>,<br>
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code = <i>number</i>,<br>
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error = <i>string</i><br>
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}
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</tt></blockquote>
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<p class=return>
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Even when there was failure (URL not found, for example), the
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function may succeed retrieving a message body (a web page informing the
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URL was not found or some other useless page). To make sure the
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operation was successful, check the returned status <tt>code</tt>. For
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a list of the possible values and their meanings, refer to <a
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href="http://www.cs.princeton.edu/~diego/rfc/rfc2616.txt">RFC
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2616</a>.
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</p>
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<pre class=example>
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-- Requests information about a document, without downloading it.
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-- Useful, for example, if you want to display a download gauge and need
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-- to know the size of the document in advance
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response = socket.http.request {
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method = "HEAD",
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url = "http://www.tecgraf.puc-rio.br/~diego"
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}
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-- Would return the following headers:
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-- response.headers = {
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-- date = "Tue, 18 Sep 2001 20:42:21 GMT",
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-- server = "Apache/1.3.12 (Unix) (Red Hat/Linux)",
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-- ["last-modified"] = "Wed, 05 Sep 2001 06:11:20 GMT",
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-- ["content-length"] = 15652,
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-- ["connection"] = "close",
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-- ["content-Type"] = "text/html"
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-- }
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</pre>
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</blockquote>
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<p class=note id=authentication>
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Note: Some URLs are protected by their
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servers from anonymous download. For those URLs, the server must receive
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some sort of authentication along with the request or it will deny
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download and return status "401 Authentication Required".
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</p>
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<p class=note>
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The HTTP/1.1 standard defines two authentication methods: the Basic
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Authentication Scheme and the Digest Authentication Scheme, both
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explained in detail in
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<a href="http://www.cs.princeton.edu/~diego/rfc/rfc2068.txt">RFC 2068</a>.
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</p>
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<p class=note>The Basic Authentication Scheme sends
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<tt><user></tt> and
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<tt><password></tt> unencrypted to the server and is therefore
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considered unsafe. Unfortunately, by the time of this implementation,
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the wide majority of servers and browsers support the Basic Scheme only.
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Therefore, this is the method used by the toolkit whenever
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authentication is required.
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</p>
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<pre class=example>
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-- Connect to server "www.tecgraf.puc-rio.br" and tries to retrieve
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-- "~diego/auth/index.html", using the provided name and password to
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-- authenticate the request
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response = socket.http.request{
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url = "http://www.tecgraf.puc-rio.br/~diego/auth/index.html",
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user = "diego",
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password = "password"
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}
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-- Alternatively, one could fill the appropriate header and authenticate
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-- the request directly.
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headers = {
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authentication = "Basic " .. socket.code.base64("diego:password")
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}
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response = socket.http.request {
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url = "http://www.tecgraf.puc-rio.br/~diego/auth/index.html",
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headers = headers
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}
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</pre>
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<!-- request_cb +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
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<p class=name id=request_cb>
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socket.http.<b>request_cb(</b>request, response<b>)</b>
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</p>
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<p class=description>
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Performs the generic HTTP request.
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</p>
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<p class=parameters>
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The function receives two tables as parameters. The <tt>request</tt> table
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provides information about the request:
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</p>
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<blockquote><tt>
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request = {<br>
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method = <i>string</i>,<br>
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url = <i>string</i>,<br>
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headers = <i>header-table</i>,<br>
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body_cb = <i>send-callback</i>,<br>
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user = <i>string</i>,<br>
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password = <i>string</i>,<br>
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stay = <i>string</i>,<br>
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}</tt>
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</blockquote>
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<p class=parameters>
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The function uses the HTTP method specified in
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<tt>request.method</tt> on the URL <tt>request.url</tt>,
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sending <tt>request.headers</tt> along with the request. The request
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message body is sent via the send callback <tt>request.body_cb</tt>.
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If authentication information is provided, the function uses the Basic
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Authentication Scheme (see <a href="#authentication">note</a>) to
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retrieve the document. <tt>Request.user</tt> and
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<tt>request.password</tt> override those given by the
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<tt>request.url</tt>. The <tt>request.stay</tt> parameter, when set to
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anything but <b><tt>nil</tt></b>, prevents the function from automatically
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following 301 or 302 server redirect messages.
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</p>
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<p class=parameters>
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The <tt>response</tt> table specifies information about the desired
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response:
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</p>
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<blockquote><tt>
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response = {<br>
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body_cb = <i>receive-callback</i><br>
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}</tt>
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</blockquote>
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<p class=return>
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The function returns the same response table as that returned by the
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<tt>socket.http.request</tt> function, except the response message body is
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returned to the receive callback given by the
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<tt>response.body_cb</tt> field.
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</p>
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<p class=note>
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Note: For more information on callbacks, please refer to
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<a href="stream.html#stream">Streaming with callbacks</a>.
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</p>
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<p class=note>
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Note: Method names are case <em>sensitive</em>
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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#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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<p>
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<small>
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Last modified by Diego Nehab on <br>
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Sat Aug 9 01:00:41 PDT 2003
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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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