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smtpd(3tcl) | Tcl SMTP Server Package | smtpd(3tcl) |
NAME¶
smtpd - Tcl SMTP server implementationSYNOPSIS¶
package require Tcl 8.3DESCRIPTION¶
The smtpd package provides a simple Tcl-only server library for the Simple Mail Transfer Protocol as described in RFC 821 ( http://www.rfc-editor.org/rfc/rfc821.txt) and RFC 2821 ( http://www.rfc-editor.org/rfc/rfc2821.txt). By default the server will bind to the default network address and the standard SMTP port (25). This package was designed to permit testing of Mail User Agent code from a developers workstation. It does not attempt to deliver mail to your mailbox. Instead users of this package are expected to write a procedure that will be called when mail arrives. Once this procedure returns, the server has nothing further to do with the mail.SECURITY¶
On Unix platforms binding to the SMTP port requires root privileges. I would not recommend running any script-based server as root unless there is some method for dropping root privileges immediately after the socket is bound. Under Windows platforms, it is not necessary to have root or administrator privileges to bind low numbered sockets. However, security on these platforms is weak anyway. In short, this code should probably not be used as a permanently running Mail Transfer Agent on an Internet connected server, even though we are careful not to evaluate remote user input. There are many other well tested and security audited programs that can be used as mail servers for internet connected hosts.COMMANDS¶
- ::smtpd::start ?myaddr? ?port?
- Start the service listening on port or the default
port 25. If myaddr is given as a domain-style name or numerical
dotted-quad IP address then the server socket will be bound to that
network interface. By default the server is bound to all network
interfaces. For example:
set sock [::smtpd::start [info hostname] 0]
- ::smtpd::stop
- Halt the server and release the listening socket. If the
server has not been started then this command does nothing. The
::smtpd::stopped variable is set for use with vwait(3tcl).
- ::smptd::configure ?option value? ?option value ...?
- Set configuration options for the SMTP server. Most values are the name of a callback procedure to be called at various points in the SMTP protocol. See the CALLBACKS section for details of the procedures.
- -banner text
- Text of a custom banner message. The default banner is "tcllib smtpd 1.5". Note that changing the banner does not affect the bracketing text in the full greeting, printing status 220, server-address, and timestamp.
- -validate_host proc
- Callback to authenticate new connections based on the ip-address of the client.
- -validate_sender proc
- Callback to authenticate new connections based on the senders email address.
- -validate_recipient proc
- Callback to validate and authorize a recipient email address
- -deliverMIME proc
- Callback used to deliver mail as a mime token created by the tcllib mime package.
- -deliver proc
- Callback used to deliver email. This option has no effect if the -deliverMIME option has been set.
- ::smtpd::cget ?option?
- If no option is specified the command will return a list of all options and their current values. If an option is specified it will return the value of that option.
CALLBACKS¶
- validate_host callback
- This procedure is called with the clients ip address as
soon as a connection request has been accepted and before any protocol
commands are processed. If you wish to deny access to a specific host then
an error should be returned by this callback. For example:
proc validate_host {ipnum} { if {[string match "192.168.1.*" $ipnum]} { error "go away!" } }
550 Access denied: I hate you.
- validate_sender callback
- The validate_sender callback is called with the senders
mail address during processing of a MAIL command to allow you to accept or
reject mail based upon the declared sender. To reject mail you should
throw an error. For example, to reject mail from user "denied":
proc validate_sender {address} { eval array set addr [mime::parseaddress $address] if {[string match "denied" $addr(local)]} { error "mailbox $addr(local) denied" } return }
- validate_recipient callback
- The validate_recipient callback is similar to the validate_sender callback and permits you to verify a local mailbox and accept mail for a local user address during RCPT command handling. To reject mail, throw an error as above. The error message is ignored.
- deliverMIME callback
- ] The deliverMIME callback is called once a mail message
has been successfully passed to the server. A mime token is constructed
from the sender, recipients and data and the users procedure it called
with this single argument. When the call returns, the mime token is
cleaned up so if the user wishes to preserve the data she must make a
copy.
proc deliverMIME {token} { set sender [lindex [mime::getheader $token From] 0] set recipients [lindex [mime::getheader $token To] 0] set mail "From $sender [clock format [clock seconds]]" append mail "\n" [mime::buildmessage $token] puts $mail }
- deliver callback
- The deliver callback is called once a mail message has been
successfully passed to the server and there is no -deliverMIME option set.
The procedure is called with the sender, a list of recipients and the text
of the mail as a list of lines. For example:
proc deliver {sender recipients data} { set mail "From $sender [clock format [clock seconds]]" append mail "\n" [join $data "\n"] puts "$mail" }
VARIABLES¶
- ::smtpd::stopped
- This variable is set to true during the ::smtpd::stop command to permit the use of the vwait(3tcl) command.
AUTHOR¶
Written by Pat Thoyts mailto:patthoyts@users.sourceforge.net.LICENSE¶
This software is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the file " license.terms" for more details.BUGS, IDEAS, FEEDBACK¶
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category smtpd of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may have for either package and/or documentation.KEYWORDS¶
rfc 2821, rfc 821, services, smtp, smtpd, socket, vwaitCATEGORY¶
NetworkingCOPYRIGHT¶
Copyright (c) Pat Thoyts <patthoyts@users.sourceforge.net>
1.5 | smtpd |