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<center><h1>Module <a href="type_Ftp_client.html">Ftp_client</a></h1></center>
<br>
<pre><span class="keyword">module</span> Ftp_client: <code class="code">sig</code> <a href="Ftp_client.html">..</a> <code class="code">end</code></pre>FTP client
<p>
Warning: Experimental code! Not all features described in this interface
work as described!
<p>
The client is currently only partially implemented. Especially, the
STOR and STOU commands are missing. Only IPv4 is supported.
<p>
It is intended to implement a large subset of RFC 959 (and later,
the newer FTP-related RFCs). This includes support for EBCDIC,
record files, and block mode.<br>
<hr width="100%">
<pre><span class="keyword">exception</span> <a name="EXCEPTIONFTP_protocol_error"></a>FTP_protocol_error <span class="keyword">of</span> <code class="type">exn</code></pre>
<div class="info">
Something went wrong, often on socket level<br>
</div>
<pre><span class="keyword">exception</span> <a name="EXCEPTIONFTP_protocol_violation"></a>FTP_protocol_violation <span class="keyword">of</span> <code class="type">string</code></pre>
<div class="info">
The server violates the FTP specification<br>
</div>
<pre><span class="keyword">type</span> <a name="TYPEcmd_state"></a><code class="type"></code>cmd_state = <code class="type">[ `Failure<br> | `Init<br> | `Pass_acct_seq<br> | `Preliminary<br> | `Proto_error<br> | `Rename_seq<br> | `Restart_seq<br> | `Success<br> | `User_acct_seq<br> | `User_pass_seq ]</code> </pre>
<div class="info">
The command state:<ul>
<li><code class="code">`Init</code>: Just connected, no greeting message arrived yet</li>
<li><code class="code">`Success</code>: Got the greeting message/last command was successful</li>
<li><code class="code">`Proto_error</code>: <b>currently unused</b></li>
<li><code class="code">`Failure</code>: Last command was not successful</li>
<li><code class="code">`Rename_seq</code>: Used instead of <code class="code">`Success</code> after the RNFR command</li>
<li><code class="code">`Restart_seq</code>: Used instead of <code class="code">`Success</code> after the REST command</li>
<li><code class="code">`User_pass_seq</code>: Used instead of <code class="code">`Success</code> after the USER command
when a password must be typed in</li>
<li><code class="code">`User_acct_seq</code>: Used instead of <code class="code">`Success</code> after the USER command
when an account ID must be typed in</li>
<li><code class="code">`Pass_acct_seq</code>: Used instead of <code class="code">`Success</code> after the PASS command
when an account iD must be typed in</li>
<li><code class="code">`Preliminary</code>: a reply with code 100 to 199. There will be another
final reply for the command</li>
</ul>
<br>
</div>
<pre><span class="keyword">type</span> <a name="TYPEport"></a><code class="type"></code>port = <code class="type">[ `Active of string * int * Unix.file_descr<br> | `Passive of string * int<br> | `Unspecified ]</code> </pre>
<div class="info">
The port of the data connection: <code class="code">`Active</code> means that the server
initiates the data connection to the listening client, and in the
case of <code class="code">`Passive</code> the client initiates the data connection to the
listening server. The string argument is the IP address as dotted
quad, the int argument is the port number, and the descriptor
is the listening master socket.<br>
</div>
<pre><span class="keyword">type</span> <a name="TYPEform_code"></a><code class="type"></code>form_code = <code class="type">[ `ASA | `Non_print | `Telnet ]</code> </pre>
<div class="info">
The <code class="code">form_code</code> has a meaning when FTP is used to print files:<ul>
<li><code class="code">`Non_print</code>: This is not the case.</li>
<li><code class="code">`Telnet</code>: Telnet control codes are used for vertical movement</li>
<li><code class="code">`ASA</code>: ASA (Fortran) control codes are used for vertical movement</li>
</ul>
<br>
</div>
<pre><span class="keyword">type</span> <a name="TYPErepresentation"></a><code class="type"></code>representation = <code class="type">[ `ASCII of <a href="Ftp_client.html#TYPEform_code">form_code</a> option<br> | `EBCDIC of <a href="Ftp_client.html#TYPEform_code">form_code</a> option<br> | `Image ]</code> </pre>
<div class="info">
The representation of the transferred file:<ul>
<li><code class="code">`ASCII</code>: An ASCII variant is used, i.e. the server sends files in
ASCII encoding with CR/LF as end-of-line marker. Supported by all
servers.</li>
<li><code class="code">`EBCDIC</code>: An EBCDIC variant is used, i.e. the server sends files in
EBCDIC encoding with NEL as end-of-line marker</li>
<li><code class="code">`Image</code>: The file is transferred in its original binary
representation. Supported by all servers.</li>
</ul>
"Local" representations are not supported.
<p>
This FTP client does not recode the files such that they match the
selected representation. When files are downloaded, they are stored
as they are received. When files are uploaded, they are sent as they
are. The user of this client must do recodings when necessary
(the class <a href="Ftp_data_endpoint.data_converter.html"><code class="code">Ftp_data_endpoint.data_converter</code></a> may be useful for this).
<p>
If no representation is selected, FTP servers assume <code class="code">`ASCII None</code>
as default.<br>
</div>
<pre><span class="keyword">type</span> <a name="TYPEstructure"></a><code class="type"></code>structure = <code class="type">[ `File_structure | `Record_structure ]</code> </pre>
<div class="info">
The client supports two structures:<ul>
<li><code class="code">`File_structure</code>: Files are simply contiguous streams of bytes</li>
<li><code class="code">`Record_structure</code>: Files are sequences of records. FTP does
not make a difference between variable and fixed length records.
It is not forbidden that the records are themselves structured
into lines, in fact it can happen that end-of-line markers are
contained in binary records. Operating systems that support
record-structured files often store text files in this format, i.e.
every line is stored in its own record, without end-of-line marker.
If record structure is selected by a STRU command, it is recommended
to use the classes <a href="Ftp_data_endpoint.out_record_channel.html"><code class="code">Ftp_data_endpoint.out_record_channel</code></a> and
<a href="Ftp_data_endpoint.in_record_channel.html"><code class="code">Ftp_data_endpoint.in_record_channel</code></a> for the local representation
of the files, otherwise the records may be incorrectly mapped
to the local conventions.</li>
</ul>
Page-structured files (i.e. indexed files) are not supported.
<p>
If no structure is selected, FTP servers will assume file structure
as default.<br>
</div>
<pre><span class="keyword">type</span> <a name="TYPEtransmission_mode"></a><code class="type"></code>transmission_mode = <code class="type">[ `Block_mode | `Stream_mode ]</code> </pre>
<div class="info">
The transmission mode selects how the data are encoded in the data
connection.<ul>
<li><code class="code">`Stream_mode</code>: This is the simple format that is responsible for
all the failed FTP downloads. It is supported by all FTP servers,
actually, you cannot assume a better transmission mode from an
unknown FTP server. It is unreliable because it cannot distinguish
between a transmission failure and the regular end-of-file condition.</li>
<li><code class="code">`Block_mode</code>: This is an improved format using frames to protect
the transmitted data. Unfortunately, almost no FTP server supports
it.</li>
</ul>
Both modes are compatible with both structures, i.e. you can transfer
a record-structured file in stream mode and a flat file in block
mode. However, in practise this is not the case. Servers that only
know flat files are likely to only support stream mode, and servers
implementing record structure imply that block transfers base on
the record format. So the advise is to use stream mode for flat
files, and block mode for record files.<br>
</div>
<br><code><span class="keyword">type</span> <a name="TYPEstate"></a><code class="type"></code>state = {</code><table class="typetable">
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>cmd_state : <code class="type"><a href="Ftp_client.html#TYPEcmd_state">cmd_state</a></code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>the command state</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>ftp_connected : <code class="type">bool</code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>whether connected with the server</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>ftp_data_conn : <code class="type">bool</code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>whether there is a clean data conn</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>ftp_user : <code class="type">string option</code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>successfully sent user identifier</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>ftp_password : <code class="type">string option</code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>successfully sent password</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>ftp_account : <code class="type">string option</code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>successfully sent account identifier</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>ftp_logged_in : <code class="type">bool</code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>whether the user is logged in</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>ftp_port : <code class="type"><a href="Ftp_client.html#TYPEport">port</a></code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>the selected port</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>ftp_repr : <code class="type"><a href="Ftp_client.html#TYPErepresentation">representation</a></code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>the selected representation</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>ftp_structure : <code class="type"><a href="Ftp_client.html#TYPEstructure">structure</a></code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>the selected structure</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>ftp_trans : <code class="type"><a href="Ftp_client.html#TYPEtransmission_mode">transmission_mode</a></code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>the selected trans mode</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code>ftp_dir : <code class="type">string list</code>;</code></td>
<td class="typefieldcomment" align="left" valign="top" ><code>(*</code></td><td class="typefieldcomment" align="left" valign="top" ><code>The current directory, expressed as list of CWD changes minus
CDUP changes. This is only reasonable if CWD does not include
slashes. The list is in reverse order, i.e. deepest directory
first.</code></td><td class="typefieldcomment" align="left" valign="bottom" ><code>*)</code></td>
</tr></table>
}
<div class="info">
The state reflects the knowledge of the client about what has been
agreed upon with the server.<br>
</div>
<pre><span class="keyword">type</span> <a name="TYPEcmd"></a><code class="type"></code>cmd = <code class="type">[ `ACCT of string<br> | `ALLO of int * int option<br> | `APPE of string * (<a href="Ftp_client.html#TYPEstate">state</a> -> <a href="Ftp_data_endpoint.html#TYPElocal_sender">Ftp_data_endpoint.local_sender</a>)<br> | `CDUP<br> | `CWD of string<br> | `Connect<br> | `DELE of string<br> | `HELP of string option<br> | `LIST of<br> string option * (<a href="Ftp_client.html#TYPEstate">state</a> -> <a href="Ftp_data_endpoint.html#TYPElocal_receiver">Ftp_data_endpoint.local_receiver</a>)<br> | `MKD of string<br> | `MODE of <a href="Ftp_client.html#TYPEtransmission_mode">transmission_mode</a><br> | `NLST of<br> string option * (<a href="Ftp_client.html#TYPEstate">state</a> -> <a href="Ftp_data_endpoint.html#TYPElocal_receiver">Ftp_data_endpoint.local_receiver</a>)<br> | `NOOP<br> | `PASS of string<br> | `PASV<br> | `PORT<br> | `PWD<br> | `QUIT<br> | `REIN<br> | `REST of string<br> | `RETR of string * (<a href="Ftp_client.html#TYPEstate">state</a> -> <a href="Ftp_data_endpoint.html#TYPElocal_receiver">Ftp_data_endpoint.local_receiver</a>)<br> | `RMD of string<br> | `RNFR of string<br> | `RNTO of string<br> | `SITE of string<br> | `SMNT of string<br> | `STAT of string option<br> | `STOR of string * (<a href="Ftp_client.html#TYPEstate">state</a> -> <a href="Ftp_data_endpoint.html#TYPElocal_sender">Ftp_data_endpoint.local_sender</a>)<br> | `STOU of unit -> <a href="Ftp_data_endpoint.html#TYPElocal_sender">Ftp_data_endpoint.local_sender</a><br> | `STRU of <a href="Ftp_client.html#TYPEstructure">structure</a><br> | `SYST<br> | `TYPE of <a href="Ftp_client.html#TYPErepresentation">representation</a><br> | `USER of string ]</code> </pre>
<div class="info">
An FTP command. <b>Currently, STOR, STOU and APPE are not supported.</b><br>
</div>
<pre><span class="keyword">type</span> <a name="TYPEreply"></a><code class="type"></code>reply = <code class="type">int * string</code> </pre>
<div class="info">
Reply code plus text<br>
</div>
<pre><span class="keyword">class</span> <a name="TYPEftp_client_pi"></a><a href="Ftp_client.ftp_client_pi.html">ftp_client_pi</a> : <code class="type">?event_system:Unixqueue.event_system -> ?onempty:<a href="Ftp_client.html#TYPEstate">state</a> -> unit -> ?onclose:unit -> unit -> Unix.file_descr -> </code><code class="code">object</code> <a href="Ftp_client.ftp_client_pi.html">..</a> <code class="code">end</code></pre><div class="info">
The client protocol interpreter...
</div>
<pre><span class="keyword">class type</span> <a name="TYPEftp_method"></a><a href="Ftp_client.ftp_method.html">ftp_method</a> = <code class="code">object</code> <a href="Ftp_client.ftp_method.html">..</a> <code class="code">end</code></pre><div class="info">
An <code class="code">ftp_method</code> is a small procedure doing some task
</div>
<pre><span class="keyword">exception</span> <a name="EXCEPTIONFTP_method_failure"></a>FTP_method_failure <span class="keyword">of</span> <code class="type">int * string</code></pre>
<div class="info">
This exception may be raised during execution by the FTP method.
The int is the unexpected FTP control code and the string the
corresponding text.
<p>
<b>This does not work yet as intended!</b><br>
</div>
<pre><span class="keyword">class</span> <a name="TYPEconnect_method"></a><a href="Ftp_client.connect_method.html">connect_method</a> : <code class="type">host:string -> ?port:int -> unit -> </code><code class="type"><a href="Ftp_client.ftp_method.html">ftp_method</a></code></pre><div class="info">
This method connects to the <code class="code">host</code> which must be an IP address
</div>
<pre><span class="keyword">class</span> <a name="TYPElogin_method"></a><a href="Ftp_client.login_method.html">login_method</a> : <code class="type">user:string -> get_password:(unit -> string) -> get_account:(unit -> string) -> unit -> </code><code class="type"><a href="Ftp_client.ftp_method.html">ftp_method</a></code></pre><div class="info">
This FTP method logs the <code class="code">user</code> in.
</div>
<pre><span class="keyword">class</span> <a name="TYPEget_method"></a><a href="Ftp_client.get_method.html">get_method</a> : <code class="type">file:string -> representation:<a href="Ftp_client.html#TYPErepresentation">representation</a> -> store:(<a href="Ftp_client.html#TYPEstate">state</a> -> <a href="Ftp_data_endpoint.html#TYPElocal_receiver">Ftp_data_endpoint.local_receiver</a>) -> unit -> </code><code class="type"><a href="Ftp_client.ftp_method.html">ftp_method</a></code></pre><div class="info">
This FTP method walks to the right directory and gets <code class="code">file</code> from
the server.
</div>
<pre><span class="keyword">class</span> <a name="TYPEftp_client"></a><a href="Ftp_client.ftp_client.html">ftp_client</a> : <code class="type">?event_system:Unixqueue.event_system -> ?onempty:unit -> unit -> unit -> </code><code class="code">object</code> <a href="Ftp_client.ftp_client.html">..</a> <code class="code">end</code></pre><div class="info">
The ftp client is a user session that may even span several connections.
</div>
<br>
<a name="2_ExamplesandDiscussion"></a>
<h2>Examples and Discussion</h2>
<p>
To download a single flat file from a server:
<p>
<pre><code class="code">
let buffer = Buffer.create 1000 in
let ch = new Netchannels.output_buffer buffer in
let client = new ftp_client() in
client # add (new connect_method ~host:"127.0.0.1");
client # add (new login_method ~user:"foo"
~get_password:(fun () -> "password")
~get_account:(fun () -> "foo") ());
client # add (new get_method ~file:"path/to/file"
~representation:`Image
~store:(fun _ -> `File_structure ch) ());
client # run()
</code></pre>
<p>
The file is stored in <code class="code">buffer</code>. By using a different netchannel, it
can be stored whereever wanted.
<p>
This piece of code has the disadvantage that the client does not stop
when a method fails (<b>in the current version, it always stops, but
in a disadvantegous manner - this will be changed</b>). Because of this,
it is better to execute the next method only when the previous
was successful:
<p>
<pre><code class="code">
...
client # add ~onsuccess:(fun () ->
client # add ~onsuccess:...
(new login_method
~user:"foo"
~get_password:(fun () -> "password")
~get_account:(fun () -> "foo") ());
)
(new connect_method ~host:"127.0.0.1")
</code></pre>
<p>
Alternatively, one can also force that the execution stops by raising
an exception in the <code class="code">onerror</code> callback (<b>not implemented in the current
version</b>).
<p>
To download a record-structured text file, use a <code class="code">store</code> like:
<p>
<pre><code class="code">
let ch = (as above) in
let rec_ch = new Ftp_data_endpoint.write_out_record_channel
~repr:(`ASCII_unix `Enc_iso88591)
ch
...
... ~store:(fun _ -> `Record_structure rec_ch)
</code></pre>
<p>
Here, the end-of-record is transcoded to newline. Note that the ASCII
variant (<code class="code">`Enc_iso88591</code>) is ignored by <code class="code">write_out_record_channel</code>.
<b>Open: How to select record structure using an FTP method.</b>
<p>
Character conversions: To convert an EBCDIC file to ASCII, use
something like
<p>
<pre><code class="code">
let ch = (as above) in
let converter = new Ftp_data_endpoint.data_converter
~fromrepr:(`EBCDIC `Enc_cp1047)
~torepr:(`ASCII_unix `Enc_iso88591) in
let ch_ebcdic = new Netchannels.output_filter converter ch in
...
... ~representation:(`EBCDIC None)
... ~store:(fun _ -> `File_structure ch_ebcdic)
</code></pre>
<p>
The class <code class="code">data_converter</code> also performs the transformation of the
end-of-line convention, unlike the similar class
<code class="code">Netconversion.conversion_pipe</code>.<br>
</body></html>
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