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LuaSocket 2.0.2 + CMake build description.
author Eric Wing <ewing . public |-at-| gmail . com>
date Tue, 26 Aug 2008 18:40:01 -0700
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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="home.html">home</a> &middot;
28 <a href="home.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>
42 HTTP (Hyper Text Transfer Protocol) is the protocol used to exchange
43 information between web-browsers and servers. The <tt>http</tt>
44 namespace offers full support for the client side of the HTTP
45 protocol (i.e.,
46 the facilities that would be used by a web-browser implementation). The
47 implementation conforms to the HTTP/1.1 standard,
48 <a href="http://www.cs.princeton.edu/~diego/rfc/rfc2616.txt">RFC
49 2616</a>.
50 </p>
51
52 <p>
53 The module exports functions that provide HTTP functionality in different
54 levels of abstraction. From the simple
55 string oriented requests, through generic
56 <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.
57 </p>
58
59 <p>
60 To obtain the <tt>http</tt> namespace, run:
61 </p>
62
63 <pre class=example>
64 -- loads the HTTP module and any libraries it requires
65 local http = require("socket.http")
66 </pre>
67
68 <p>
69 URLs must conform to
70 <a href="http://www.cs.princeton.edu/~diego/rfc/rfc1738.txt">RFC
71 1738</a>,
72 that is, an URL is a string in the form:
73 </p>
74
75 <blockquote>
76 <pre>
77 [http://][&lt;user&gt;[:&lt;password&gt;]@]&lt;host&gt;[:&lt;port&gt;][/&lt;path&gt;]
78 </pre>
79 </blockquote>
80
81 <p>
82 MIME headers are represented as a Lua table in the form:
83 </p>
84
85 <blockquote>
86 <table summary="MIME headers in Lua table">
87 <tr><td><tt>
88 headers = {<br>
89 &nbsp;&nbsp;field-1-name = <i>field-1-value</i>,<br>
90 &nbsp;&nbsp;field-2-name = <i>field-2-value</i>,<br>
91 &nbsp;&nbsp;field-3-name = <i>field-3-value</i>,<br>
92 &nbsp;&nbsp;...<br>
93 &nbsp;&nbsp;field-n-name = <i>field-n-value</i><br>
94 }
95 </tt></td></tr>
96 </table>
97 </blockquote>
98
99 <p>
100 Field names are case insensitive (as specified by the standard) and all
101 functions work with lowercase field names.
102 Field values are left unmodified.
103 </p>
104
105 <p class=note>
106 Note: MIME headers are independent of order. Therefore, there is no problem
107 in representing them in a Lua table.
108 </p>
109
110 <p>
111 The following constants can be set to control the default behavior of
112 the HTTP module:
113 </p>
114
115 <ul>
116 <li> <tt>PORT</tt>: default port used for connections;
117 <li> <tt>PROXY</tt>: default proxy used for connections;
118 <li> <tt>TIMEOUT</tt>: sets the timeout for all I/O operations;
119 <li> <tt>USERAGENT</tt>: default user agent reported to server.
120 </ul>
121
122 <!-- http.request ++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
123
124 <p class=name id=request>
125 http.<b>request(</b>url [, body]<b>)</b><br>
126 http.<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>
140 The request function has two forms. The simple form downloads
141 a URL using the <tt>GET</tt> or <tt>POST</tt> method and is based
142 on 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>
147 If the first argument of the <tt>request</tt> function is a string, it
148 should be an <tt>url</tt>. In that case, if a <tt>body</tt>
149 is provided as a string, the function will perform a <tt>POST</tt> method
150 in the <tt>url</tt>. Otherwise, it performs a <tt>GET</tt> in the
151 <tt>url</tt>
152 </p>
153
154 <p class=parameters>
155 If the first argument is instead a table, the most important fields are
156 the <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.
159 Any part of the <tt>url</tt> can be overridden by including
160 the appropriate field in the request table.
161 If authentication information is provided, the function
162 uses the Basic Authentication Scheme (see <a href="#authentication">note</a>)
163 to retrieve the document. If <tt>sink</tt> is <tt><b>nil</b></tt>, the
164 function discards the downloaded data. The optional parameters are the
165 following:
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>
172 source to provide the request body. If there
173 is a body, you need to provide an appropriate "<tt>content-length</tt>"
174 request 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>
178 pump step function used to move data.
179 Defaults 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
182 function 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>
188 In case of failure, the function returns <tt><b>nil</b></tt> followed by an
189 error message. If successful, the simple form returns the response
190 body as a string, followed by the response status code, the response
191 headers and the response status line. The generic function returns the same
192 information, except the first return value is just the number 1 (the body
193 goes to the <tt>sink</tt>).
194 </p>
195
196 <p class=return>
197 Even when the server fails to provide the contents of the requested URL (URL not found, for example),
198 it usually returns a message body (a web page informing the
199 URL was not found or some other useless page). To make sure the
200 operation was successful, check the returned status <tt>code</tt>. For
201 a list of the possible values and their meanings, refer to <a
202 href="http://www.cs.princeton.edu/~diego/rfc/rfc2616.txt">RFC
203 2616</a>.
204 </p>
205
206 <p class=description>
207 Here are a few examples with the simple interface:
208 </p>
209
210 <pre class=example>
211 -- load the http module
212 local io = require("io")
213 local http = require("socket.http")
214 local ltn12 = require("ltn12")
215
216 -- connect to server "www.cs.princeton.edu" and retrieves this manual
217 -- file from "~diego/professional/luasocket/http.html" and print it to stdout
218 http.request{
219 url = "http://www.cs.princeton.edu/~diego/professional/luasocket/http.html",
220 sink = ltn12.sink.file(io.stdout)
221 }
222
223 -- connect to server "www.example.com" and tries to retrieve
224 -- "/private/index.html". Fails because authentication is needed.
225 b, c, h = http.request("http://www.example.com/private/index.html")
226 -- b returns some useless page telling about the denied access,
227 -- h returns authentication information
228 -- and c returns with value 401 (Authentication Required)
229
230 -- tries to connect to server "wrong.host" to retrieve "/"
231 -- and fails because the host does not exist.
232 r, e = http.request("http://wrong.host/")
233 -- r is nil, and e returns with value "host not found"
234 </pre>
235
236 <p class=description>
237 And here is an example using the generic interface:
238 </p>
239
240 <pre class=example>
241 -- load the http module
242 http = require("socket.http")
243
244 -- Requests information about a document, without downloading it.
245 -- Useful, for example, if you want to display a download gauge and need
246 -- to know the size of the document in advance
247 r, c, h = http.request {
248 method = "HEAD",
249 url = "http://www.tecgraf.puc-rio.br/~diego"
250 }
251 -- r is 1, c is 200, and h would return the following headers:
252 -- h = {
253 -- date = "Tue, 18 Sep 2001 20:42:21 GMT",
254 -- server = "Apache/1.3.12 (Unix) (Red Hat/Linux)",
255 -- ["last-modified"] = "Wed, 05 Sep 2001 06:11:20 GMT",
256 -- ["content-length"] = 15652,
257 -- ["connection"] = "close",
258 -- ["content-Type"] = "text/html"
259 -- }
260 </pre>
261
262 <p class=note id=post>
263 Note: When sending a POST request, simple interface adds a
264 "<tt>Content-type: application/x-www-form-urlencoded</tt>"
265 header to the request. This is the type used by
266 HTML forms. If you need another type, use the generic
267 interface.
268 </p>
269
270 <p class=note id=authentication>
271 Note: Some URLs are protected by their
272 servers from anonymous download. For those URLs, the server must receive
273 some sort of authentication along with the request or it will deny
274 download and return status "401&nbsp;Authentication Required".
275 </p>
276
277 <p class=note>
278 The HTTP/1.1 standard defines two authentication methods: the Basic
279 Authentication Scheme and the Digest Authentication Scheme, both
280 explained in detail in
281 <a href="http://www.cs.princeton.edu/~diego/rfc/rfc2068.txt">RFC 2068</a>.
282 </p>
283
284 <p class=note>The Basic Authentication Scheme sends
285 <tt>&lt;user&gt;</tt> and
286 <tt>&lt;password&gt;</tt> unencrypted to the server and is therefore
287 considered unsafe. Unfortunately, by the time of this implementation,
288 the wide majority of servers and browsers support the Basic Scheme only.
289 Therefore, this is the method used by the toolkit whenever
290 authentication is required.
291 </p>
292
293 <pre class=example>
294 -- load required modules
295 http = require("socket.http")
296 mime = require("mime")
297
298 -- Connect to server "www.example.com" and tries to retrieve
299 -- "/private/index.html", using the provided name and password to
300 -- authenticate the request
301 b, c, h = http.request("http://fulano:silva@www.example.com/private/index.html")
302
303 -- Alternatively, one could fill the appropriate header and authenticate
304 -- the request directly.
305 r, c = http.request {
306 url = "http://www.example.com/private/index.html",
307 headers = { authentication = "Basic " .. (mime.b64("fulano:silva")) }
308 }
309 </pre>
310
311 <!-- footer +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
312
313 <div class=footer>
314 <hr>
315 <center>
316 <p class=bar>
317 <a href="home.html">home</a> &middot;
318 <a href="home.html#download">download</a> &middot;
319 <a href="installation.html">installation</a> &middot;
320 <a href="introduction.html">introduction</a> &middot;
321 <a href="reference.html">reference</a>
322 </p>
323 <p>
324 <small>
325 Last modified by Diego Nehab on <br>
326 Thu Apr 20 00:25:26 EDT 2006
327 </small>
328 </p>
329 </center>
330 </div>
331
332 </body>
333 </html>