1Net::Cmd(3) User Contributed Perl Documentation Net::Cmd(3)
2
6 Net::Cmd - Network Command class (as used by FTP, SMTP etc)
7
9 use Net::Cmd;
10 @ISA = qw(Net::Cmd);
12
14 "Net::Cmd" is a collection of methods that can be inherited by a sub-
15 class of "IO::Socket::INET". These methods implement the functionality
16 required for a command based protocol, for example FTP and SMTP.
17 If your sub-class does not also derive from "IO::Socket::INET" or
19 similar (e.g. "IO::Socket::IP", "IO::Socket::INET6" or
20 "IO::Socket::SSL") then you must provide the following methods by other
21 means yourself: "close()" and "timeout()".
22 Public Methods
24 These methods provide a user interface to the "Net::Cmd" object.
25 "debug($level)"
27 Set the level of debug information for this object. If $level is
28 not given then the current state is returned. Otherwise the state
29 is changed to $level and the previous state returned.
30 Different packages may implement different levels of debug but a
32 non-zero value results in copies of all commands and responses also
33 being sent to STDERR.
34 If $level is "undef" then the debug level will be set to the
36 default debug level for the class.
37 This method can also be called as a static method to set/get the
39 default debug level for a given class.
40 "message()"
42 Returns the text message returned from the last command. In a
43 scalar context it returns a single string, in a list context it
44 will return each line as a separate element. (See "PSEUDO
45 RESPONSES" below.)
46 "code()"
48 Returns the 3-digit code from the last command. If a command is
49 pending then the value 0 is returned. (See "PSEUDO RESPONSES"
50 below.)
51 "ok()"
53 Returns non-zero if the last code value was greater than zero and
54 less than 400. This holds true for most command servers. Servers
55 where this does not hold may override this method.
56 "status()"
58 Returns the most significant digit of the current status code. If a
59 command is pending then "CMD_PENDING" is returned.
60 "datasend($data)"
62 Send data to the remote server, converting LF to CRLF. Any line
63 starting with a '.' will be prefixed with another '.'. $data may
64 be an array or a reference to an array. The $data passed in must
65 be encoded by the caller to octets of whatever encoding is
66 required, e.g. by using the Encode module's "encode()" function.
67 "dataend()"
69 End the sending of data to the remote server. This is done by
70 ensuring that the data already sent ends with CRLF then sending
71 '.CRLF' to end the transmission. Once this data has been sent
72 "dataend" calls "response" and returns true if "response" returns
73 CMD_OK.
74 Protected Methods
76 These methods are not intended to be called by the user, but used or
77 over-ridden by a sub-class of "Net::Cmd"
78 "debug_print($dir, $text)"
80 Print debugging information. $dir denotes the direction true being
81 data being sent to the server. Calls "debug_text" before printing
82 to STDERR.
83 "debug_text($dir, $text)"
85 This method is called to print debugging information. $text is the
86 text being sent. The method should return the text to be printed.
87 This is primarily meant for the use of modules such as FTP where
89 passwords are sent, but we do not want to display them in the
90 debugging information.
91 "command($cmd[, $args, ... ])"
93 Send a command to the command server. All arguments are first
94 joined with a space character and CRLF is appended, this string is
95 then sent to the command server.
96 Returns undef upon failure.
98 "unsupported()"
100 Sets the status code to 580 and the response text to 'Unsupported
101 command'. Returns zero.
102 "response()"
104 Obtain a response from the server. Upon success the most
105 significant digit of the status code is returned. Upon failure,
106 timeout etc., CMD_ERROR is returned.
107 "parse_response($text)"
109 This method is called by "response" as a method with one argument.
110 It should return an array of 2 values, the 3-digit status code and
111 a flag which is true when this is part of a multi-line response and
112 this line is not the last.
113 "getline()"
115 Retrieve one line, delimited by CRLF, from the remote server.
116 Returns undef upon failure.
117 NOTE: If you do use this method for any reason, please remember to
119 add some "debug_print" calls into your method.
120 "ungetline($text)"
122 Unget a line of text from the server.
123 "rawdatasend($data)"
125 Send data to the remote server without performing any conversions.
126 $data is a scalar. As with "datasend()", the $data passed in must
127 be encoded by the caller to octets of whatever encoding is
128 required, e.g. by using the Encode module's "encode()" function.
129 "read_until_dot()"
131 Read data from the remote server until a line consisting of a
132 single '.'. Any lines starting with '..' will have one of the '.'s
133 removed.
134 Returns a reference to a list containing the lines, or undef upon
136 failure.
137 "tied_fh()"
139 Returns a filehandle tied to the Net::Cmd object. After issuing a
140 command, you may read from this filehandle using read() or <>. The
141 filehandle will return EOF when the final dot is encountered.
142 Similarly, you may write to the filehandle in order to send data to
143 the server after issuing a command that expects data to be written.
144 See the Net::POP3 and Net::SMTP modules for examples of this.
146 Pseudo Responses
148 Normally the values returned by "message()" and "code()" are obtained
149 from the remote server, but in a few circumstances, as detailed below,
150 "Net::Cmd" will return values that it sets. You can alter this behavior
151 by overriding DEF_REPLY_CODE() to specify a different default reply
152 code, or overriding one of the specific error handling methods below.
153 Initial value
155 Before any command has executed or if an unexpected error occurs
156 "code()" will return "421" (temporary connection failure) and
157 "message()" will return undef.
158 Connection closed
160 If the underlying "IO::Handle" is closed, or if there are any read
161 or write failures, the file handle will be forced closed, and
162 "code()" will return "421" (temporary connection failure) and
163 "message()" will return "[$pkg] Connection closed" (where $pkg is
164 the name of the class that subclassed "Net::Cmd"). The
165 _set_status_closed() method can be overridden to set a different
166 message (by calling set_status()) or otherwise trap this error.
167 Timeout
169 If there is a read or write timeout "code()" will return "421"
170 (temporary connection failure) and "message()" will return "[$pkg]
171 Timeout" (where $pkg is the name of the class that subclassed
172 "Net::Cmd"). The _set_status_timeout() method can be overridden to
173 set a different message (by calling set_status()) or otherwise trap
174 this error.
175
177 The following symbols are, or can be, exported by this module:
178 Default Exports
180 "CMD_INFO", "CMD_OK", "CMD_MORE", "CMD_REJECT", "CMD_ERROR",
181 "CMD_PENDING".
182 (These correspond to possible results of "response()" and
184 "status()".)
185 Optional Exports
187 None.
188 Export Tags
190 None.
191
193 See <https://rt.cpan.org/Dist/Display.html?Status=Active&Queue=libnet>.
194
196 Graham Barr <gbarr@pobox.com <mailto:gbarr@pobox.com>>.
197 Steve Hay <shay@cpan.org <mailto:shay@cpan.org>> is now maintaining
199 libnet as of version 1.22_02.
200
202 Copyright (C) 1995-2006 Graham Barr. All rights reserved.
203 Copyright (C) 2013-2016, 2020 Steve Hay. All rights reserved.
205
207 This module is free software; you can redistribute it and/or modify it
208 under the same terms as Perl itself, i.e. under the terms of either the
209 GNU General Public License or the Artistic License, as specified in the
210 LICENCE file.
211
213 Version 3.14
214
216 23 Dec 2020
217
219 See the Changes file.
220perl v5.36.0 2022-07-22 Net::Cmd(3)