# Tcl MIME

Dover Beach Consulting, Inc.

    POB 255268
    Sacramento CA 95865-5268
    US

    +1 916 483 8878
    +1 916 483 8848
    mrose@dbc.mtview.ca.us

Tcl MIME generates and parses MIME body parts.

# SYNOPSIS

package provide mime 1.2 package provide smtp 1.2
Tcl MIME is an implementation of a Tcl package that generates and parses MIME body parts.
Each MIME part consists of a header (zero or more key/value pairs), an empty line, and a structured body. A MIME part is either a "leaf" or has (zero or more) subordinates.
MIME defines four keys that may appear in the headers: describes the data contained in the body ("the content"); describes how the content is encoded for transmission in an ASCII stream; a textual description of the content; and, a globally-unique identifier for the content.
Consult for a list of standard content types. Further, consult for a list of several other header keys (e.g., "To", "cc", etc.)
A simple example might be:
Date: Sun, 04 July 1999 10:38:25 -0600 From: Marshall Rose <mrose@dbc.mtview.ca.us> To: Andreas Kupries <a.kupries@westend.com> cc: dnew@messagemedia.com (Darren New) MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Description: a simple example Content-ID: <4294407315.931384918.1@dbc.mtview.ca.us>

Here is the body. In this case, simply plain text.
In addition to an implementation of the mime package, Tcl MIME includes an implementation of the smtp package.

## Requirements

This package requires: Tcl/Tk version 8.0.3 or later
In addition, this package requires one of the following:
Trf version 2.0p5
or later
base 64 version 2.0
or later (included with tcllib)
If it is available, Trf will be used to provide better performance; if not, Tcl-only equivalent functions, based on the base64 package, are used.

## Copyrights

(c) 1999-2000 Marshall T. Rose
Hold harmless the author, and any lawful use is allowed.

# SYNTAX

mime::initialize returns a token. Parameters:
?-canonical type/subtype ?-param {key value}?... ?-encoding value? ?-header {key value}?... ? (-file name | -string value | -parts {token1 ... tokenN})
mime::finalize returns an empty string. Parameters:
token ?-subordinates "all" | "dynamic" | "none"?
mime::getproperty returns a string or a list of strings. Parameters:
token ?property | -names?
mime::getheader returns a list of strings. Parameters:
token ?key | -names?
mime::setheader returns a list of strings. Parameters:
token key value ?-mode "write" | "append" | "delete"?
mime::getbody returns a string. Parameters:
?-command callback ?-blocksize octets? ?
mime::copymessage returns an empty string. Parameters:
token channel
mime::buildmessage returns an empty string. Parameters:
token
smtp::sendmessage returns a list. Parameters:
token ?-servers list? ?-ports list? ?-queue boolean? ?-atleastone boolean? ?-originator string? ?-recipients string? ?-header {key value}?...
mime::parseaddress returns a list of serialized arrays. Parameters:
string
mime::parsedatetime returns a string. Parameters:
[string | -now] property
mime::mapencoding returns a string. Parameters:
encoding_name
mime::reversemapencoding returns a string. Parameters:
content_type

# SEMANTICS

## mime::initialize

mime::initialize creates a MIME part: If the -canonical option is present, then the body is in canonical (raw) form and is found by consulting either the -file, -string, or -part option. In addition, both the -param and -header options may occur zero or more times to specify "Content-Type" parameters (e.g., "charset") and header keyword/values (e.g., "Content-Disposition"), respectively. Also, -encoding, if present, specifies the "Content-Transfer-Encoding" when copying the body. If the -canonical option is not present, then the MIME part contained in either the -file or the -string option is parsed, dynamically generating subordinates as appropriate.

## mime::finalize

mime::finalize destroys a MIME part.
If the -subordinates option is present, it specifies which subordinates should also be destroyed. The default value is "dynamic".

## mime::getproperty

mime::getproperty returns the properties of a MIME part.
The properties are:
property value ======== ===== content the type/subtype describing the content encoding the "Content-Transfer-Encoding" params a list of "Content-Type" parameters parts a list of tokens for the part's subordinates size the approximate size of the content (unencoded)
The "parts" property is present only if the MIME part has subordinates.
If mime::getproperty is invoked with the name of a specific property, then the corresponding value is returned; instead, if -names is specified, a list of all properties is returned; otherwise, a serialized array of properties and values is returned.

## mime::getheader

mime::getheader returns the header of a MIME part.
A header consists of zero or more key/value pairs. Each value is a list containing one or more strings.
If mime::getheader is invoked with the name of a specific key, then a list containing the corresponding value(s) is returned; instead, if -names is specified, a list of all keys is returned; otherwise, a serialized array of keys and values is returned. Note that when a key is specified (e.g., "Subject"), the list returned usually contains exactly one string; however, some keys (e.g., "Received") often occur more than once in the header, accordingly the list returned usually contains more than one string.

## mime::setheader

mime::setheader writes, appends to, or deletes the value associated with a key in the header.
The value for -mode is one of: the key/value is either created or overwritten (the default); a new value is appended for the key (creating it as necessary); or, all values associated with the key are removed (the "value" parameter is ignored).
Regardless, mime::setheader returns the previous value associated with the key.

## mime::getbody

mime::getbody returns the body of a leaf MIME part in canonical form.
If the -command option is present, then it is repeatedly invoked with a fragment of the body as this:
uplevel #0 $callback [list "data" $fragment]
(The -blocksize option, if present, specifies the maximum size of each fragment passed to the callback.)
When the end of the body is reached, the callback is invoked as:
uplevel #0 $callback "end"
Alternatively, if an error occurs, the callback is invoked as:
uplevel #0 $callback [list "error" reason]
Regardless, the return value of the final invocation of the callback is propagated upwards by mime::getbody.
If the -command option is absent, then the return value of mime::getbody is a string containing the MIME part's entire body.

## mime::copymessage

mime::copymessage copies the MIME part to the specified channel.
mime::copymessage operates synchronously, and uses fileevent to allow asynchronous operations to proceed independently.

## mime::buildmessage

mime::buildmessage returns the MIME part as a string. It is similar to mime::copymessage, only it returns the data as a return string instead of writing to a channel.

## smtp::sendmessage

smtp::sendmessage sends a MIME part to an SMTP server. (Note that this procedure is in the "smtp" package, not the "mime" package.)
The options are: a list of SMTP servers (the default is "localhost"); a list of SMTP ports (the default is 25); indicates that the SMTP server should be asked to queue the message for later processing; indicates that the SMTP server must find at least one recipient acceptable for the message to be sent; a string containing an 822-style address specification (if present the header isn't examined for an originator address); a string containing one or more 822-style address specifications (if present the header isn't examined for recipient addresses); and, a keyword/value pairing (may occur zero or more times).
If the -originator option is not present, the originator address is taken from "From" (or "Resent-From"); similarly, if the -recipients option is not present, recipient addresses are taken from "To", "cc", and "Bcc" (or "Resent-To", and so on). Note that the header key/values supplied by the "-header" option (not those present in the MIME part) are consulted. Regardless, header key/values are added to the outgoing message as necessary to ensure that a valid 822-style message is sent.
smtp::sendmessage returns a list indicating which recipients were unacceptable to the SMTP server. Each element of the list is another list, containing the address, an SMTP error code, and a textual diagnostic. Depending on the -atleastone option and the intended recipients,, a non-empty list may still indicate that the message was accepted by the server.

## mime::parseaddress

mime::parseaddr takes a string containing one or more 822-style address specifications and returns a list of serialized arrays, one element for each address specified in the argument.
Each serialized array contains these properties:
property value ======== ===== address local@domain comment 822-style comment domain the domain part (rhs) error non-empty on a parse error group this address begins a group friendly user-friendly rendering local the local part (lhs) memberP this address belongs to a group phrase the phrase part proper 822-style address specification route 822-style route specification (obsolete)
Note that one or more of these properties may be empty.

## mime::parsedatetime

mime::parsedatetime takes a string containing an 822-style date-time specification and returns the specified property.
The list of properties and their ranges are:
property range ======== ===== hour 0 .. 23 lmonth January, February, ..., December lweekday Sunday, Monday, ... Saturday mday 1 .. 31 min 0 .. 59 mon 1 .. 12 month Jan, Feb, ..., Dec proper 822-style date-time specification rclock elapsed seconds between then and now sec 0 .. 59 wday 0 .. 6 (Sun .. Mon) weekday Sun, Mon, ..., Sat yday 1 .. 366 year 1900 ... zone -720 .. 720 (minutes east of GMT)

## mime::mapencoding

mime::mapencoding maps tcl encodings onto the proper names for their MIME charset type. This is only done for encodings whose charset types were known. The remaining encodings return "" for now.

## mime::reversemapencoding

mime::reversemapencoding maps MIME charset types onto tcl encoding names. Those that are unknown return "".

# EXAMPLES

package require mime 1.0 package require smtp 1.0

# create an image

set imageT [mime::initialize -canonical image/gif \ -file logo.gif]

# parse a message

set messageT [mime::initialize -file example.msg]

# recursively traverse a message looking for primary recipients

proc traverse {token} { set result ""

# depth-first search if {![catch { mime::getproperty $token parts } parts]} { foreach part $parts { set result [concat $result [traverse $part]] } }

# one value for each line occuring in the header foreach value [mime::getheader $token To] { foreach addr [mime::parseaddress $value] { catch { unset aprops } array set aprops $addr lappend result $aprops(address) } }

return $result }

# create a multipart containing both, and a timestamp

set multiT [mime::initialize -canonical multipart/mixed -parts [list $imageT $messageT]]

# send it to some friends

smtp::sendmessage $multiT \ -header [list From "Marshall Rose <mrose@dbc.mtview.ca.us>"] \ -header [list To "Andreas Kupries <a.kupries@westend.com>"] \ -header [list cc "dnew@messagemedia.com (Darren New)"] \ -header [list Subject "test message..."]

# clean everything up

mime::finalize $multiT -subordinates all

# Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies

Innosoft International, Inc.

    ned@innosoft.com

First Virtual Holdings, Incorporated

    nsb@messagemedia.com

# Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types

Innosoft International, Inc.

    ned@innosoft.com

First Virtual Holdings, Incorporated

    nsb@messagemedia.com

# Standard for the format of ARPA Internet Text Messages

University of Delaware

    DCrocker@UDel-Relay

# TODO List

well-defined errorCode values
catch nested errors when processing a multipart

# Acknowledgements

This package is influenced by the safe-tcl package (Borenstein and Rose, circa 1993), and also by Darren New's unpublished package of 1999.
This package makes use of Andreas Kupries's excellent Trf package.