Apocalypse

NAME

POE::Component::Client::SimpleFTP - A simple FTP client library for POE

VERSION

  This document describes v0.003 of POE::Component::Client::SimpleFTP - released May 04, 2011 as part of POE-Component-Client-SimpleFTP.

SYNOPSIS

        # A simple FTP client logging in to a server
        use POE qw( Component::Client::SimpleFTP );

        POE::Session->create(
                inline_states => {
                        _start => sub {
                                POE::Component::Client::SimpleFTP->new(
                                        alias => "ftp",
                                        remote_addr => "invalid.addr",
                                        username => "myuser",
                                        password => "mypassword",
                                );
                                return;
                        },
                        authenticated => sub {
                                print "LOGGED ON!\n";
                                $_[KERNEL]->post( "ftp", "quit" );
                                return;
                        }
                },
        );
        POE::Kernel->run;

DESCRIPTION

This is a simple FTP client to use in a POE application. It's a complete rewrite of the old POE::Component::Client::FTP codebase and makes it easier to use. Most of the API/event flow is compatible, so you should have few problems porting your code to this module.

You start by creating the ftp object and wait for it to send you events. By default the caller session will get all the events directed to it, no need to "register" for events or anything like that. Events are sent to you in the generic form of $command or ${command}_error events. This module will parse the FTP reply codes and determine if it is an error or not, and dispatch it to the appropriate event.

An important thing to keep in mind is that there is no command queueing done in this module. It is up to the user to know what state they are in and to dispatch events at the right time. If a command is sent while this module is processing one, an exception will be thrown. Fortunately, due to the way events are named, it should be easy to keep track of the event flow.

Initial Connection

When the object is created, it attempts to make a connection to the server specified in the attributes. It will automatically login with the provided credentials. Additionally, it will enable TLS mode if you enabled the attributes "tls_cmd" and "tls_data". There is a timeout timer on the initial connection that you can tweak via setting "timeout".

The following events may be sent to your session:

authenticated

This event is sent when the entire login procedure is done. At this point you can send commands to the server.

No arguments.

connect_error

This event is sent when there's an error connecting to the server. The component will automatically destroy itself at this point, so if you want to retry the connection, you have to make a new object.

The first argument is the error code, and the 2nd argument is the error string.

The code "0" is used here, because we never got a reply from the server. However, it is nice to have consistency with the other event handlers, so it is supplied.

Example code: 0

Example reply: timedout

login_error

This event is sent when there's an error trying to login to the server. The component will automatically destroy itself at this point, so if you want to retry the connection, you have to make a new object.

The first argument is the error code, and the 2nd argument is the error string.

Example code: 530

Example reply: Login incorrect.

Simple Commands

This is a class of commands that can be sent to the server after receiving the "authenticated" event. They perform identically, and will send the same replies back to your session. Some commands require arguments, others don't.

Normally the events will include at least 2 arguments: the FTP return code and the actual reply line from the server. If the command included arguments, it will be supplied in the event to make identifying actions easier.

Some commands is an alias for the actual command ( cd vs cwd ) but the event name will follow the aliased command. If a cwd event is sent, the error event is cwd_error. If a cd event is sent, the error event is cd_error.

        # send the cd command in an event handler somewhere
        $ftp->yield( 'cd', '/foobar' );

        # handler for the resulting event received from this component
        sub cd {
                my( $code, $reply, $path ) = @_[ ARG0 .. ARG2 ];

                # $code probably is 250
                # $reply probably is "Directory successfully changed."
                # $path will be "/foobar"
        }

        sub cd_error {
                my( $code, $reply, $path ) = @_[ ARG0 .. ARG2 ];

                # $code probably is 550
                # $reply probably is "Failed to change directory."
                # $path will be "/foobar"
        }

cwd

Changes the working directory.

Arguments: the path to change to ( required )

Example code: 250

Example reply: Directory successfully changed.

cd

An alias for "cwd"

dele

Deletes a file.

Arguments: the file to delete ( required )

Example code: 250

Example reply: Delete operation successful.

delete

An alias for "dele"

mkd

Creates a directory.

Arguments: the directory path to create ( required )

You can supply an absolute path or a relative path. It is up to the server to figure out where to create the directory. It's easier to use absolute paths so you are sure that the server is creating the directory in the right place!

Remember, the FTP protocol doesn't support recursive directory creation! If /foo exists but /foo/bar doesn't, then you cannot create /foo/bar/baz!

Example code: 257

Example reply: "/foo" created

mkdir

An alias for "mkd"

rmd

Removes a directory.

Arguments: the directory path to delete ( required )

You can supply an absolute path or a relative path. It is up to the server to figure out where to delete the directory. It's easier to use absolute paths so you are sure that the server is deleting the right directory!

Example code: 250

Example reply: Remove directory operation successful.

rmdir

An alias for "rmd"

cdup

Changes the working directory to the parent.

Remember, there might be symlinks or other bizarre stuff going on behind the scenes! It's best to supply full pathnames to "cwd" to be safe.

Arguments: none

Example code: 250

Example reply: Directory successfully changed.

pwd

Prints the current working directory.

Arguments: none

Example code: 257

Example reply: "/"

rename

Renames a target file to a new name.

Arguments: the old filename and the new filename

Remember, the pathnames must exist and is a valid target. Best to send absolute paths!

Example code: 250

Example reply: Rename successful.

mv

An alias for "rename"

quit

Disconnects from the server. Behaves differently depending on the context when this command is received. After this command is sent, this module will destroy itself and not send any more events to your session.

If this module isn't processing anything it will send the QUIT command and gracefully shutdown when it receives the server reply.

If this module is processing a command it will disconnect immediately, killing any command processing/data transfers that is happening.

If you want to force immediate shutdown, use the "shutdown" event.

Arguments: none

disconnect

An alias for "quit"

shutdown

Forces a shutdown of the component and kills everything.

Arguments: none

noop

Executes a no-operation command. Useful to keep the connection open or to get the round-trip latency, or whatever :)

Arguments: none

Example code: 200

Example reply: NOOP ok.

quot

Sends a quoted command to the server. Useful for sending commands that this module doesn't support.

Arguments: the actual command + arguments to send.

        $ftp->yield( 'quot', 'CRAZYCMD', @crazy_args );

quote

An alias for "quot"

help

Gets the server's help output for a command.

Arguments: optional command to ask for help

Example code: 214

Example reply:

        The following commands are recognized.
        ABOR ACCT ALLO APPE CDUP CWD  DELE EPRT EPSV FEAT HELP LIST MDTM MKD
        MODE NLST NOOP OPTS PASS PASV PORT PWD  QUIT REIN REST RETR RMD  RNFR
        RNTO SITE SIZE SMNT STAT STOR STOU STRU SYST TYPE USER XCUP XCWD XMKD
        XPWD XRMD
        Help OK.

site

Executes a specific command that the server supports. Consult your ftp administrator or the document for the ftpd software for more information.

Arguments: the command to execute + any optional arguments.

Example code: 500

Example reply: Unknown SITE command.

stat

Receives some informational text about the current status of the connection.

BEWARE: While the RFC says this command can be sent while a data transfer is in progress, this is unimplemented!

Arguments: none

Example code: 211

Example reply:

        FTP server status:
        Connected to 192.168.0.199
        Logged in as apoc
        TYPE: ASCII
        No session bandwidth limit
        Session timeout in seconds is 300
        Control connection is plain text
        Data connections will be plain text
        At session startup, client count was 1
        vsFTPd 2.2.0 - secure, fast, stable
        End of status

syst

Gets the system information of the server.

Arguments: none

Example code: 215

Example reply: UNIX Type: L8

acct

Send the account information for your login. Generally not used, but if your server requires it you should send this immediately after getting the "authenticated" event.

Arguments: your account information

Example code: 502

Example reply: ACCT not implemented.

smnt

Mounts a different filesystem volume on your account. Generally not used.

Arguments: a pathname to mount or system-specific string

Example code: 502

Example reply: SMNT not implemented.

mdtm

Gets the modification time of a file. Not supported by all servers! ( RFC 3659 )

Arguments: the file to query

Example code: 213

Example reply: 20110502230157

You can use the "mdtm_parser" in POE::Component::Client::SimpleFTP::Utils function to convert it into a DateTime object.

size

Gets the size of a file in bytes. Not supported by all servers! ( RFC 3659 )

Arguments: the file to query

Example code: 213

Example reply: 48

feat

Queries the FEAT capabilities of the server. Not supported by all servers! ( RFC 2389 )

Arguments: none

Example code: 211

Example reply:

        Features:
        EPRT
        EPSV
        MDTM
        PASV
        REST STREAM
        SIZE
        TVFS
        UTF8
        End

You can use the "feat_parser" in POE::Component::Client::SimpleFTP::Utils function to convert it into an array of features.

features

An alias for "feat"

opts

Sets an option for the current session. Not supported by all servers! ( RFC 2389 )

Arguments: the option to set

Example code: 501

Example reply: Option not understood.

options

An alias for "opts"

Complex Commands

This class of commands is called complex because they require opening a new data connection to the server. The requested data is transferred over this connection, and the result is sent back to your session. All of the commands behave the same except for the "upload" types.

Please look at the examples directory included in this distribution for code samples.

The typical flow of this command is as follows:

        $ftp->yield( 'get', "/myfile.txt" );

        # receive a "get_connected" event
        #       args is: "/myfile.txt"

        # at this point you prepare to process the incoming data

        # receive a "get_data" event
        #       args is: $chunk, "/myfile.txt"

        # at this point you should write out the data to the terminal, a file, or whatever!

        # ... keep receiving "get_data" until the server finish sending

        # receive a "get" event
        #       args is: $code, $reply, "/myfile.txt"

        # at this point the transfer is complete

        # if at any point there is an error, a "get_error" event is sent
        #       args is: $code, $reply, "/myfile.txt"

For the "upload" events where you are sending data to the server, the flow is:

        $ftp->yield( 'put', '/myfile.txt' );

        # receive a "put_connected" event
        #       args is: "/myfile"

        # at this point you should get the data to send to the server
        # from your local filesystem, from a database server, or whatever!

        # send a chunk of data to the server
        # the chunk size should depend on your application - a reasonable default is 10240 bytes
        $ftp->yield( 'put_data', $chunk );

        # receive a "put_flushed" event
        #       args is: "/myfile"

        # at this point, you can either send another chunk or signal EOF
        $ftp->yield( 'put_close' );

        # receive a "put" event
        #       args is: $code, $reply, "/myfile"

        # at this point the transfer is complete

        # if at any point there is an error, a "put_error" event is sent
        #       args is: $code, $reply, "/myfile"

list

Receives a directory list. The data is sent in a format similar to the UNIX "ls" command, but can be anything!

Arguments: the optional path to query ( defaults to current working directory )

Example data:

        drwxr-xr-x    4 1000     1000         4096 May 02 18:24 a
        drwxr-xr-x    4 1000     1000         4096 May 02 18:24 b
        drwxr-xr-x    4 1000     1000         4096 May 02 18:24 c
        -rw-r--r--    1 1000     1000            0 May 02 20:26 foo.txt

ls

An alias for list

nlst

Receives a directory list. Differs from list in that only the names are received.

Arguments: the optional path to query ( defaults to current working directory )

Example data:

        a
        b
        c
        foo.txt

dir

An alias for "nlst"

retr

Retrieves a file from the server.

Arguments: the filename to receive

get

An alias for "get"

stor

Transmits a file to the server. This uses the "upload" command flow explained in "Complex Commands"!

Arguments: the filename to put

stou

Transmits a file to the server. This differs from "stor" in that the ftp server is required to store the file in a unique way. This uses the "upload" command flow explained in "Complex Commands"!

Arguments: the filename to put

put

An alias for "stor"

ATTRIBUTES

alias

The alias this component will use. You can send commands to the ftpd in 2 ways:

        my $ftp = POE::Component::Client::SimpleFTP->new( alias => "ftp", ... );
        $poe_kernel->post( 'ftp', 'cd', 'foobar' );

        # Or, you can use the yield sub:
        $ftp->yield( 'cd', 'foobar' );

The default is: ftp

username

The FTP username you will be sending to the server.

required.

password

The FTP password you will be sending to the server.

required.

remote_addr

The IP address of the FTP server to connect to. Can be a DNS hostname or IPv4/6 string.

required.

remote_port

The port of the FTP server to connect to.

The default is: 21

local_addr

The local IP address to bind to for all connections to the server.

The default is: INADDR_ANY ( let the OS decide )

local_port

The local port to bind to for the control connection to the server. If you need to change the data connection's port, please change the "local_data_port" attribute.

The default is: 0 ( let the OS decide )

local_data_port

The local port to bind to for the data connection to the server. Must be a different port than the "local_port" attribute!

The default is: 0 ( let the OS decide )

tls_cmd

A boolean value to enable/disable TLS encryption of the command connection. If you want to use this, you must have POE::Component::SSLify installed!

The default is: false

tls_data

A boolean value to enable/disable TLS encryption of the data connection. If you want to use this, you must have POE::Component::SSLify installed!

The default is: false

timeout

A value specifying the timeout in seconds for the initial connection to the FTP server.

The default is: 120

connection_mode

Determine what connection mode we will be using when opening the data connection to the server. In "active" mode, the server will be connecting to us. In "passive" mode we will be connecting to the server. You usually need "passive" mode if you are behind a firewall.

The default is: passive

FUNCTIONS

DEBUG

Enable this if you want to get debugging output. Do it like this:

        sub POE::Component::Client::SimpleFTP::DEBUG () { 1 }
        use POE::Component::Client::SimpleFTP;

The default is: false

yield

This method provides an alternative object based means of posting events to the component. First argument is the event to post, following arguments are sent as arguments to the resultant post.

        my $ftp = POE::Component::Client::SimpleFTP->new( ... );
        $ftp->yield( 'cd', 'foobar' );

        # equivalent to:
        $poe_kernel->post( $ftp->alias, 'cd', 'foobar' );

TLS support

TLS encryption is available if you want. You would need to enable the "tls_cmd" and "tls_data" attributes and have POE::Component::SSLify installed in order to use it. It should work with a lot of servers and commands. However, not the entire specification is implemented! If you encounter problems when using TLS on a server, please let me know by filing a bug report!

Unimplemented Commands/Actions/Features

Those are the ideas that probably will be implemented in a future version. Some of them require core changes to this module, while others can be done in user-space but should be implemented here to make it "simpler" :)

        * full TLS support - check the RFCs
        * FXP ( server<->server ) transfers
        * intelligent NAT detection
        * full ipv6 compatibility
        * restart/abort/append a transfer
        * bandwidth throttling for data connection
        * support for "mkdir -p" where this module automatically creates all directories needed
        * passing a filename/filehandle/whatever to put/get so this module automatically does the reading/writing
        * directory mirroring ( ala rsync )
        * use POE::Filter::Ls for parsing ( need to improve it first hah )
        * encoded pathnames ( translate \012 in filename to \000 as per RFC 959 )
        * security stuff - http://cr.yp.to/ftp/security.html
        * event prefix ( so you get ftp_cd events instead of cd ) for easier event management
        * strict command validation ( we don't check if the command requires 0, 1, or N args )

RFC 959 "FILE TRANSFER PROTOCOL (FTP)"

        * REIN ( not allowed, as it generally screws up - just reconnect! )
        * STRU ( default file type is always a good idea )
        * MODE ( default stream type is always a good idea )
        * APPE ( should be easy to implement, but im lazy )
        * ALLO ( it is generally unused and obsolete? )
        * REST ( a bit tricky to implement, maybe later )
        * ABOR ( not allowed, as it generally screws up - just disconnect! )
        * PASV ( this module automatically does it )
        * PORT ( this module automatically does it )
        * TYPE ( this module automatically does it )
        * STAT ( implemented, but not allowed while a transfer is in progress as it generally screws things up )

RFC 2228 "FTP Security Extensions"

        * AUTH ( only AUTH TLS is supported now )
        * PROT/PBSZ is supported with the default options if you enable tls_cmd/tls_data
        * ADAT ( not needed for AUTH TLS? )
        * CCC ( not needed with TLS? )
        * MIC ( not needed with TLS? )
        * CONF ( not needed with TLS? )
        * ENC ( not needed with TLS? )

RFC 2389 "Feature negotiation mechanism for the File Transfer Protocol"

        * The entire RFC is implemented

RFC 2428 "FTP Extensions for IPv6 and NATs"

        * EPRT
        * EPSV

RFC 2577 "FTP Security Considerations"

        * unimplemented

RFC 2640 "Internationalization of the File Transfer Protocol"

        * unimplemented

RFC 3659 "Extensions to FTP"

        * REST ( same reason as the RFC 959 one )
        * MLST
        * MLSD

RFC 4217 "Securing FTP with TLS"

        * unimplemented except for what is implemented in 2228 :)

RFC 5796 "FTP Command and Extension Registry"

        * No need to implement this, it is for servers only

SUPPORT

Perldoc

You can find documentation for this module with the perldoc command.

  perldoc POE::Component::Client::SimpleFTP

Websites

The following websites have more information about this module, and may be of help to you. As always, in addition to those websites please use your favorite search engine to discover more resources.

Email

You can email the author of this module at APOCAL at cpan.org asking for help with any problems you have.

Internet Relay Chat

You can get live help by using IRC ( Internet Relay Chat ). If you don't know what IRC is, please read this excellent guide: http://en.wikipedia.org/wiki/Internet_Relay_Chat. Please be courteous and patient when talking to us, as we might be busy or sleeping! You can join those networks/channels and get help:

  • irc.perl.org

    You can connect to the server at 'irc.perl.org' and join this channel: #perl-help then talk to this person for help: Apocalypse.

  • irc.freenode.net

    You can connect to the server at 'irc.freenode.net' and join this channel: #perl then talk to this person for help: Apocal.

  • irc.efnet.org

    You can connect to the server at 'irc.efnet.org' and join this channel: #perl then talk to this person for help: Ap0cal.

Bugs / Feature Requests

Please report any bugs or feature requests by email to bug-poe-component-client-simpleftp at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=POE-Component-Client-SimpleFTP. You will be automatically notified of any progress on the request by the system.

Source Code

The code is open to the world, and available for you to hack on. Please feel free to browse it and play with it, or whatever. If you want to contribute patches, please send me a diff or prod me to pull from your repository :)

http://github.com/apocalypse/perl-poe-component-simpleftp

  git clone git://github.com/apocalypse/perl-poe-component-simpleftp.git

AUTHOR

Apocalypse <APOCAL@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2011 by Apocalypse.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

The full text of the license can be found in the LICENSE file included with this distribution.

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.




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