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FTP (File Transfer Protocol) is a protocol used to transfer files
between hosts. The <tt>ftp</tt> namespace offers thorough support
to FTP, under a simple interface. The implementation conforms to
<a href="http://www.ietf.org/rfc/rfc959.txt">RFC 959</a>.

High level functions are provided supporting the most common operations.
These high level functions are implemented on top of a lower level
interface. Using the low-level interface, users can easily create their
own functions to access any operation supported by the FTP
protocol. For that, check the implementation.

To really benefit from this module, a good understanding of 
<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">
LTN012, Filters sources and sinks</a> is necessary.

To obtain the <tt>ftp</tt> namespace, run:

<pre class=example>
-- loads the FTP module and any libraries it requires
local ftp = require("socket.ftp")
</pre>

URLs MUST conform to
<a href="http://www.ietf.org/rfc/rfc1738.txt">RFC 1738</a>, 
that is, an URL is a string in the form:

<blockquote>
<tt>
[ftp://][&lt;user&gt;[:&lt;password&gt;]@]&lt;host&gt;[:&lt;port&gt;][/&lt;path&gt;][type=a|i]</tt>
</blockquote>

The following constants in the namespace can be set to control the default behavior of
the FTP module:

<ul>
<li> <tt>PASSWORD</tt>: default anonymous password.
<li> <tt>PORT</tt>: default port used for the control connection;
<li> <tt>TIMEOUT</tt>: sets the timeout for all I/O operations;
<li> <tt>USER</tt>: default anonymous user;
</ul>

ftp.get(url) 
ftp.get{ 
&nbsp;&nbsp;host = string, 
&nbsp;&nbsp;sink = LTN12 sink, 
&nbsp;&nbsp;argument or path = string, 
&nbsp;&nbsp;[user = string,] 
&nbsp;&nbsp;[password = string] 
&nbsp;&nbsp;[command = string,] 
&nbsp;&nbsp;[port = number,] 
&nbsp;&nbsp;[type = string,] 
&nbsp;&nbsp;[step = LTN12 pump step,] 
&nbsp;&nbsp;[create = function] 
}

The <tt>get</tt> function has two forms. The simple form has fixed
functionality: it downloads the contents of a URL and returns it as a
string. The generic form allows a lot more control, as explained
below.

If the argument of the <tt>get</tt> function is a table, the function
expects at least the fields <tt>host</tt>, <tt>sink</tt>, and one of 
<tt>argument</tt> or <tt>path</tt> (<tt>argument</tt> takes
precedence). <tt>Host</tt> is the server to connect to. <tt>Sink</tt> is
the simple 
<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
sink that will receive the downloaded data. <tt>Argument</tt> or
<tt>path</tt> give the target path to the resource in the server. The
optional arguments are the following:

<ul>
<li><tt>user</tt>, <tt>password</tt>: User name and password used for
authentication. Defaults to "<tt>ftp:anonymous@anonymous.org</tt>";
<li><tt>command</tt>: The FTP command used to obtain data. Defaults to
"<tt>retr</tt>", but see example below;
<li><tt>port</tt>: The port to used for the control connection. Defaults to 21;
<li><tt>type</tt>: The transfer mode. Can take values "<tt>i</tt>" or
"<tt>a</tt>". Defaults to whatever is the server default;
<li><tt>step</tt>: 
<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a>
pump step function used to pass data from the
server to the sink. Defaults to the LTN12 <tt>pump.step</tt> function;
<li><tt>create</tt>: An optional function to be used instead of
<a href=tcp.html#socket.tcp><tt>socket.tcp</tt></a> when the communications socket is created. 
</ul>

If successful, the simple version returns the URL contents as a
string, and the generic function returns 1. In case of error, both
functions return <tt>nil</tt> and an error message describing the
error.

<pre class=example>
-- load the ftp support
local ftp = require("socket.ftp")

-- Log as user "anonymous" on server "ftp.tecgraf.puc-rio.br",
-- and get file "lua.tar.gz" from directory "pub/lua" as binary.
f, e = ftp.get("ftp://ftp.tecgraf.puc-rio.br/pub/lua/lua.tar.gz;type=i")
</pre>

<pre class=example>
-- load needed modules
local ftp = require("socket.ftp")
local ltn12 = require("ltn12")
local url = require("socket.url")

-- a function that returns a directory listing
function nlst(u)
 local t = {}
 local p = url.parse(u)
 p.command = "nlst"
 p.sink = ltn12.sink.table(t)
 local r, e = ftp.get(p)
 return r and table.concat(t), e
end
</pre>

ftp.put(url, content) 
ftp.put{ 
&nbsp;&nbsp;host = string, 
&nbsp;&nbsp;source = LTN12 sink, 
&nbsp;&nbsp;argument or path = string, 
&nbsp;&nbsp;[user = string,] 
&nbsp;&nbsp;[password = string] 
&nbsp;&nbsp;[command = string,] 
&nbsp;&nbsp;[port = number,] 
&nbsp;&nbsp;[type = string,] 
&nbsp;&nbsp;[step = LTN12 pump step,] 
&nbsp;&nbsp;[create = function] 
}

The <tt>put</tt> function has two forms. The simple form has fixed
functionality: it uploads a string of content into a URL. The generic form
allows a lot more control, as explained below.

If the argument of the <tt>put</tt> function is a table, the function
expects at least the fields <tt>host</tt>, <tt>source</tt>, and one of 
<tt>argument</tt> or <tt>path</tt> (<tt>argument</tt> takes
precedence). <tt>Host</tt> is the server to connect to. <tt>Source</tt> is
the simple 
<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a> 
source that will provide the contents to be uploaded. 
<tt>Argument</tt> or
<tt>path</tt> give the target path to the resource in the server. The
optional arguments are the following:

<ul>
<li><tt>user</tt>, <tt>password</tt>: User name and password used for
authentication. Defaults to "<tt>ftp:anonymous@anonymous.org</tt>";
<li><tt>command</tt>: The FTP command used to send data. Defaults to
"<tt>stor</tt>", but see example below;
<li><tt>port</tt>: The port to used for the control connection. Defaults to 21;
<li><tt>type</tt>: The transfer mode. Can take values "<tt>i</tt>" or
"<tt>a</tt>". Defaults to whatever is the server default;
<li><tt>step</tt>: 
<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">LTN12</a> 
pump step function used to pass data from the
server to the sink. Defaults to the LTN12 <tt>pump.step</tt> function;
<li><tt>create</tt>: An optional function to be used instead of
<a href=tcp.html#socket.tcp><tt>socket.tcp</tt></a> when the communications socket is created. 
</ul>

Both functions return 1 if successful, or <tt>nil</tt> and an error
message describing the reason for failure.

<pre class=example>
-- load the ftp support
local ftp = require("socket.ftp")

-- Log as user "fulano" on server "ftp.example.com",
-- using password "silva", and store a file "README" with contents 
-- "wrong password, of course"
f, e = ftp.put("ftp://fulano:silva@ftp.example.com/README", 
 "wrong password, of course")
</pre>

<pre class=example>
-- load the ftp support
local ftp = require("socket.ftp")
local ltn12 = require("ltn12")

-- Log as user "fulano" on server "ftp.example.com",
-- using password "silva", and append to the remote file "LOG", sending the
-- contents of the local file "LOCAL-LOG"
f, e = ftp.put{
 host = "ftp.example.com", 
 user = "fulano",
 password = "silva",
 command = "appe",
 argument = "LOG",
 source = ltn12.source.file(io.open("LOCAL-LOG", "r"))
}
</pre>

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Last modified by Diego Nehab on 
Thu Apr 20 00:25:18 EDT 2006


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