Net::Cmd(3pm) Perl Programmers Reference Guide Net::Cmd(3pm)
NAME
Net::Cmd - Network Command class (as used by FTP, SMTP etc)
SYNOPSIS
use Net::Cmd;
@ISA = qw(Net::Cmd);
DESCRIPTION
"Net::Cmd" is a collection of methods that can be inherited by a sub-
class of "IO::Socket::INET". These methods implement the functionality
required for a command based protocol, for example FTP and SMTP.
If your sub-class does not also derive from "IO::Socket::INET" or
similar (e.g. "IO::Socket::IP", "IO::Socket::INET6" or
"IO::Socket::SSL") then you must provide the following methods by other
means yourself: "close()" and "timeout()".
Public Methods
These methods provide a user interface to the "Net::Cmd" object.
"debug($level)"
Set the level of debug information for this object. If $level is
not given then the current state is returned. Otherwise the state
is changed to $level and the previous state returned.
Different packages may implement different levels of debug but a
non-zero value results in copies of all commands and responses also
being sent to STDERR.
If $level is "undef" then the debug level will be set to the
default debug level for the class.
This method can also be called as a static method to set/get the
default debug level for a given class.
"message()"
Returns the text message returned from the last command. In a
scalar context it returns a single string, in a list context it
will return each line as a separate element. (See "PSEUDO
RESPONSES" below.)
"code()"
Returns the 3-digit code from the last command. If a command is
pending then the value 0 is returned. (See "PSEUDO RESPONSES"
below.)
"ok()"
Returns non-zero if the last code value was greater than zero and
less than 400. This holds true for most command servers. Servers
where this does not hold may override this method.
"status()"
Returns the most significant digit of the current status code. If a
command is pending then "CMD_PENDING" is returned.
"datasend($data)"
Send data to the remote server, converting LF to CRLF. Any line
starting with a '.' will be prefixed with another '.'. $data may
be an array or a reference to an array. The $data passed in must
be encoded by the caller to octets of whatever encoding is
required, e.g. by using the Encode module's "encode()" function.
"dataend()"
End the sending of data to the remote server. This is done by
ensuring that the data already sent ends with CRLF then sending
'.CRLF' to end the transmission. Once this data has been sent
"dataend" calls "response" and returns true if "response" returns
CMD_OK.
Protected Methods
These methods are not intended to be called by the user, but used or
over-ridden by a sub-class of "Net::Cmd"
"debug_print($dir, $text)"
Print debugging information. $dir denotes the direction true being
data being sent to the server. Calls "debug_text" before printing
to STDERR.
"debug_text($dir, $text)"
This method is called to print debugging information. $text is the
text being sent. The method should return the text to be printed.
This is primarily meant for the use of modules such as FTP where
passwords are sent, but we do not want to display them in the
debugging information.
"command($cmd[, $args, ... ])"
Send a command to the command server. All arguments are first
joined with a space character and CRLF is appended, this string is
then sent to the command server.
Returns undef upon failure.
"unsupported()"
Sets the status code to 580 and the response text to 'Unsupported
command'. Returns zero.
"response()"
Obtain a response from the server. Upon success the most
significant digit of the status code is returned. Upon failure,
timeout etc., CMD_ERROR is returned.
"parse_response($text)"
This method is called by "response" as a method with one argument.
It should return an array of 2 values, the 3-digit status code and
a flag which is true when this is part of a multi-line response and
this line is not the last.
"getline()"
Retrieve one line, delimited by CRLF, from the remote server.
Returns undef upon failure.
NOTE: If you do use this method for any reason, please remember to
add some "debug_print" calls into your method.
"ungetline($text)"
Unget a line of text from the server.
"rawdatasend($data)"
Send data to the remote server without performing any conversions.
$data is a scalar. As with "datasend()", the $data passed in must
be encoded by the caller to octets of whatever encoding is
required, e.g. by using the Encode module's "encode()" function.
"read_until_dot()"
Read data from the remote server until a line consisting of a
single '.'. Any lines starting with '..' will have one of the '.'s
removed.
Returns a reference to a list containing the lines, or undef upon
failure.
"tied_fh()"
Returns a filehandle tied to the Net::Cmd object. After issuing a
command, you may read from this filehandle using read() or <>. The
filehandle will return EOF when the final dot is encountered.
Similarly, you may write to the filehandle in order to send data to
the server after issuing a command that expects data to be written.
See the Net::POP3 and Net::SMTP modules for examples of this.
Pseudo Responses
Normally the values returned by "message()" and "code()" are obtained
from the remote server, but in a few circumstances, as detailed below,
"Net::Cmd" will return values that it sets. You can alter this behavior
by overriding DEF_REPLY_CODE() to specify a different default reply
code, or overriding one of the specific error handling methods below.
Initial value
Before any command has executed or if an unexpected error occurs
"code()" will return "421" (temporary connection failure) and
"message()" will return undef.
Connection closed
If the underlying "IO::Handle" is closed, or if there are any read
or write failures, the file handle will be forced closed, and
"code()" will return "421" (temporary connection failure) and
"message()" will return "[$pkg] Connection closed" (where $pkg is
the name of the class that subclassed "Net::Cmd"). The
_set_status_closed() method can be overridden to set a different
message (by calling set_status()) or otherwise trap this error.
Timeout
If there is a read or write timeout "code()" will return "421"
(temporary connection failure) and "message()" will return "[$pkg]
Timeout" (where $pkg is the name of the class that subclassed
"Net::Cmd"). The _set_status_timeout() method can be overridden to
set a different message (by calling set_status()) or otherwise trap
this error.
EXPORTS
The following symbols are, or can be, exported by this module:
Default Exports
"CMD_INFO", "CMD_OK", "CMD_MORE", "CMD_REJECT", "CMD_ERROR",
"CMD_PENDING".
(These correspond to possible results of "response()" and
"status()".)
Optional Exports
None.
Export Tags
None.
KNOWN BUGS
See <https://rt.cpan.org/Dist/Display.html?Status=Active&Queue=libnet>.
AUTHOR
Graham Barr <gbarr@pobox.com <mailto:gbarr@pobox.com>>.
Steve Hay <shay@cpan.org <mailto:shay@cpan.org>> is now maintaining
libnet as of version 1.22_02.
COPYRIGHT
Copyright (C) 1995-2006 Graham Barr. All rights reserved.
Copyright (C) 2013-2016, 2020 Steve Hay. All rights reserved.
LICENCE
This module is free software; you can redistribute it and/or modify it
under the same terms as Perl itself, i.e. under the terms of either the
GNU General Public License or the Artistic License, as specified in the
LICENCE file.
VERSION
Version 3.13
DATE
23 Dec 2020
HISTORY
See the Changes file.
perl v5.34.0 2021-01-20 Net::Cmd(3pm)
perl 5.34.0 - Generated Thu Mar 3 07:51:25 CST 2022