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1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
2 "http://www.w3.org/TR/html4/strict.dtd">
3<html>
4
5<head>
6<meta name="description" content="LuaSocket: HTTP support">
7<meta name="keywords" content="Lua, HTTP, Library, WWW, Browser, Network, Support">
8<title>LuaSocket: HTTP support</title>
9<link rel="stylesheet" href="reference.css" type="text/css">
10</head>
11
12<body>
13
14<!-- header ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
15
16<div class=header>
17<hr>
18<center>
19<table summary="LuaSocket logo">
20<tr><td align=center><a href="http://www.lua.org">
21<img width=128 height=128 border=0 alt="LuaSocket" src="luasocket.png">
22</a></td></tr>
23<tr><td align=center valign=top>Network support for the Lua language
24</td></tr>
25</table>
26<p class=bar>
27<a href="index.html">home</a> &middot;
28<a href="index.html#download">download</a> &middot;
29<a href="introduction.html">introduction</a> &middot;
30<a href="introduction.html">introduction</a> &middot;
31<a href="reference.html">reference</a>
32</p>
33</center>
34<hr>
35</div>
36
37<!-- http +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
38
39<h2 id="http">HTTP</h2>
40
41<p>
42HTTP (Hyper Text Transfer Protocol) is the protocol used to exchange
43information between web-browsers and servers. The <tt>http</tt>
44namespace offers full support for the client side of the HTTP
45protocol (i.e.,
46the facilities that would be used by a web-browser implementation). The
47implementation conforms to the HTTP/1.1 standard,
48<a href="http://www.ietf.org/rfc/rfc2616.txt">RFC 2616</a>.
49</p>
50
51<p>
52The module exports functions that provide HTTP functionality in different
53levels of abstraction. From the simple
54string oriented requests, through generic
55<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a> based, down to even lower-level if you bother to look through the source code.
56</p>
57
58<p>
59To obtain the <tt>http</tt> namespace, run:
60</p>
61
62<pre class=example>
63-- loads the HTTP module and any libraries it requires
64local http = require("socket.http")
65</pre>
66
67<p>
68URLs must conform to
69<a href="http://www.ietf.org/rfc/rfc1738.txt">RFC 1738</a>,
70that is, an URL is a string in the form:
71</p>
72
73<blockquote>
74<pre>
75[http://][&lt;user&gt;[:&lt;password&gt;]@]&lt;host&gt;[:&lt;port&gt;][/&lt;path&gt;]
76</pre>
77</blockquote>
78
79<p>
80MIME headers are represented as a Lua table in the form:
81</p>
82
83<blockquote>
84<table summary="MIME headers in Lua table">
85<tr><td><tt>
86headers = {<br>
87&nbsp;&nbsp;field-1-name = <i>field-1-value</i>,<br>
88&nbsp;&nbsp;field-2-name = <i>field-2-value</i>,<br>
89&nbsp;&nbsp;field-3-name = <i>field-3-value</i>,<br>
90&nbsp;&nbsp;...<br>
91&nbsp;&nbsp;field-n-name = <i>field-n-value</i><br>
92}
93</tt></td></tr>
94</table>
95</blockquote>
96
97<p>
98Field names are case insensitive (as specified by the standard) and all
99functions work with lowercase field names (but see
100<a href=socket.html#headers.canonic><tt>socket.headers.canonic</tt></a>).
101Field values are left unmodified.
102</p>
103
104<p class=note>
105Note: MIME headers are independent of order. Therefore, there is no problem
106in representing them in a Lua table.
107</p>
108
109<p>
110The following constants can be set to control the default behavior of
111the HTTP module:
112</p>
113
114<ul>
115<li> <tt>PORT</tt>: default port used for connections;
116<li> <tt>PROXY</tt>: default proxy used for connections;
117<li> <tt>TIMEOUT</tt>: sets the timeout for all I/O operations;
118<li> <tt>USERAGENT</tt>: default user agent reported to server.
119</ul>
120
121
122<!-- http.request ++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
123
124<p class=name id="request">
125http.<b>request(</b>url [, body]<b>)</b><br>
126http.<b>request{</b><br>
127&nbsp;&nbsp;url = <i>string</i>,<br>
128&nbsp;&nbsp;[sink = <i>LTN12 sink</i>,]<br>
129&nbsp;&nbsp;[method = <i>string</i>,]<br>
130&nbsp;&nbsp;[headers = <i>header-table</i>,]<br>
131&nbsp;&nbsp;[source = <i>LTN12 source</i>],<br>
132&nbsp;&nbsp;[step = <i>LTN12 pump step</i>,]<br>
133&nbsp;&nbsp;[proxy = <i>string</i>,]<br>
134&nbsp;&nbsp;[redirect = <i>boolean</i>,]<br>
135&nbsp;&nbsp;[create = <i>function</i>]<br>
136<b>}</b>
137</p>
138
139<p class=description>
140The request function has two forms. The simple form downloads
141a URL using the <tt>GET</tt> or <tt>POST</tt> method and is based
142on strings. The generic form performs any HTTP method and is
143<a href=http://lua-users.org/wiki/FiltersSourcesAndSinks>LTN12</a> based.
144</p>
145
146<p class=parameters>
147If the first argument of the <tt>request</tt> function is a string, it
148should be an <tt>url</tt>. In that case, if a <tt>body</tt>
149is provided as a string, the function will perform a <tt>POST</tt> method
150in the <tt>url</tt>. Otherwise, it performs a <tt>GET</tt> in the
151<tt>url</tt>
152</p>
153
154<p class=parameters>
155If the first argument is instead a table, the most important fields are
156the <tt>url</tt> and the <em>simple</em>
157<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
158<tt>sink</tt> that will receive the downloaded content.
159Any part of the <tt>url</tt> can be overridden by including
160the appropriate field in the request table.
161If authentication information is provided, the function
162uses the Basic Authentication Scheme (see <a href="#authentication">note</a>)
163to retrieve the document. If <tt>sink</tt> is <tt><b>nil</b></tt>, the
164function discards the downloaded data. The optional parameters are the
165following:
166</p>
167<ul>
168<li><tt>method</tt>: The HTTP request method. Defaults to "GET";
169<li><tt>headers</tt>: Any additional HTTP headers to send with the request;
170<li><tt>source</tt>: <em>simple</em>
171<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
172source to provide the request body. If there
173is a body, you need to provide an appropriate "<tt>content-length</tt>"
174request header field, or the function will attempt to send the body as
175"<tt>chunked</tt>" (something few servers support). Defaults to the empty source;
176<li><tt>step</tt>:
177<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
178pump step function used to move data.
179Defaults to the LTN12 <tt>pump.step</tt> function.
180<li><tt>proxy</tt>: The URL of a proxy server to use. Defaults to no proxy;
181<li><tt>redirect</tt>: Set to <tt><b>false</b></tt> to prevent the
182function from automatically following 301 or 302 server redirect messages;
183<li><tt>create</tt>: An optional function to be used instead of
184<a href=tcp.html#socket.tcp><tt>socket.tcp</tt></a> when the communications socket is created.
185</ul>
186
187<p class=return>
188In case of failure, the function returns <tt><b>nil</b></tt> followed by an
189error message. If successful, the simple form returns the response
190body as a string, followed by the response status code, the response
191headers and the response status line. The generic function returns the same
192information, except the first return value is just the number 1 (the body
193goes to the <tt>sink</tt>).
194</p>
195
196<p class=return>
197Even when the server fails to provide the contents of the requested URL (URL not found, for example),
198it usually returns a message body (a web page informing the
199URL was not found or some other useless page). To make sure the
200operation was successful, check the returned status <tt>code</tt>. For
201a list of the possible values and their meanings, refer to <a
202href="http://www.ietf.org/rfc/rfc2616.txt">RFC 2616</a>.
203</p>
204
205<p class=description>
206Here are a few examples with the simple interface:
207</p>
208
209<pre class=example>
210-- load the http module
211local io = require("io")
212local http = require("socket.http")
213local ltn12 = require("ltn12")
214
215-- connect to server "www.cs.princeton.edu" and retrieves this manual
216-- file from "~diego/professional/luasocket/http.html" and print it to stdout
217http.request{
218 url = "http://www.cs.princeton.edu/~diego/professional/luasocket/http.html",
219 sink = ltn12.sink.file(io.stdout)
220}
221
222-- connect to server "www.example.com" and tries to retrieve
223-- "/private/index.html". Fails because authentication is needed.
224b, c, h = http.request("http://www.example.com/private/index.html")
225-- b returns some useless page telling about the denied access,
226-- h returns authentication information
227-- and c returns with value 401 (Authentication Required)
228
229-- tries to connect to server "wrong.host" to retrieve "/"
230-- and fails because the host does not exist.
231r, e = http.request("http://wrong.host/")
232-- r is nil, and e returns with value "host not found"
233</pre>
234
235<p class=description>
236And here is an example using the generic interface:
237</p>
238
239<pre class=example>
240-- load the http module
241http = require("socket.http")
242
243-- Requests information about a document, without downloading it.
244-- Useful, for example, if you want to display a download gauge and need
245-- to know the size of the document in advance
246r, c, h = http.request {
247 method = "HEAD",
248 url = "http://www.tecgraf.puc-rio.br/~diego"
249}
250-- r is 1, c is 200, and h would return the following headers:
251-- h = {
252-- date = "Tue, 18 Sep 2001 20:42:21 GMT",
253-- server = "Apache/1.3.12 (Unix) (Red Hat/Linux)",
254-- ["last-modified"] = "Wed, 05 Sep 2001 06:11:20 GMT",
255-- ["content-length"] = 15652,
256-- ["connection"] = "close",
257-- ["content-Type"] = "text/html"
258-- }
259</pre>
260
261<p class=note id="post">
262Note: When sending a POST request, simple interface adds a
263"<tt>Content-type: application/x-www-form-urlencoded</tt>"
264header to the request. This is the type used by
265HTML forms. If you need another type, use the generic
266interface.
267</p>
268
269<p class=note id="authentication">
270Note: Some URLs are protected by their
271servers from anonymous download. For those URLs, the server must receive
272some sort of authentication along with the request or it will deny
273download and return status "401&nbsp;Authentication Required".
274</p>
275
276<p class=note>
277The HTTP/1.1 standard defines two authentication methods: the Basic
278Authentication Scheme and the Digest Authentication Scheme, both
279explained in detail in
280<a href="http://www.ietf.org/rfc/rfc2068.txt">RFC 2068</a>.
281</p>
282
283<p class=note>The Basic Authentication Scheme sends
284<tt>&lt;user&gt;</tt> and
285<tt>&lt;password&gt;</tt> unencrypted to the server and is therefore
286considered unsafe. Unfortunately, by the time of this implementation,
287the wide majority of servers and browsers support the Basic Scheme only.
288Therefore, this is the method used by the toolkit whenever
289authentication is required.
290</p>
291
292<pre class=example>
293-- load required modules
294http = require("socket.http")
295mime = require("mime")
296
297-- Connect to server "www.example.com" and tries to retrieve
298-- "/private/index.html", using the provided name and password to
299-- authenticate the request
300b, c, h = http.request("http://fulano:silva@www.example.com/private/index.html")
301
302-- Alternatively, one could fill the appropriate header and authenticate
303-- the request directly.
304r, c = http.request {
305 url = "http://www.example.com/private/index.html",
306 headers = { authorization = "Basic " .. (mime.b64("fulano:silva")) }
307}
308</pre>
309
310<!-- footer +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
311
312<div class=footer>
313<hr>
314<center>
315<p class=bar>
316<a href="index.html">home</a> &middot;
317<a href="index.html#download">download</a> &middot;
318<a href="installation.html">installation</a> &middot;
319<a href="introduction.html">introduction</a> &middot;
320<a href="reference.html">reference</a>
321</p>
322<p>
323<small>
324Last modified by Diego Nehab on <br>
325Thu Apr 20 00:25:26 EDT 2006
326</small>
327</p>
328</center>
329</div>
330
331</body>
332</html>
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