

The README file                                                M.T. Rose
                                            Dover Beach Consulting, Inc.
                                                       February 22, 2000


                                Tcl MIME


Abstract

   Tcl MIME generates and parses MIME body parts.

Table of Contents

   1.   SYNOPSIS . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   1.1  Requirements . . . . . . . . . . . . . . . . . . . . . . . .   3
   1.2  Copyrights . . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.   SYNTAX . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.   SEMANTICS  . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.1  mime::initialize . . . . . . . . . . . . . . . . . . . . . .   5
   3.2  mime::finalize . . . . . . . . . . . . . . . . . . . . . . .   5
   3.3  mime::getproperty  . . . . . . . . . . . . . . . . . . . . .   5
   3.4  mime::getheader  . . . . . . . . . . . . . . . . . . . . . .   6
   3.5  mime::setheader  . . . . . . . . . . . . . . . . . . . . . .   6
   3.6  mime::getbody  . . . . . . . . . . . . . . . . . . . . . . .   6
   3.7  mime::copymessage  . . . . . . . . . . . . . . . . . . . . .   7
   3.8  mime::buildmessage . . . . . . . . . . . . . . . . . . . . .   7
   3.9  smtp::sendmessage  . . . . . . . . . . . . . . . . . . . . .   7
   3.10 mime::parseaddress . . . . . . . . . . . . . . . . . . . . .   8
   3.11 mime::parsedatetime  . . . . . . . . . . . . . . . . . . . .   9
   3.12 mime::mapencoding  . . . . . . . . . . . . . . . . . . . . .   9
   3.13 mime::reversemapencoding . . . . . . . . . . . . . . . . . .   9

   4.   EXAMPLES . . . . . . . . . . . . . . . . . . . . . . . . . .  10
        References . . . . . . . . . . . . . . . . . . . . . . . . .  12
        Author's Address . . . . . . . . . . . . . . . . . . . . . .  12
   A.   TODO List  . . . . . . . . . . . . . . . . . . . . . . . . .  13
   B.   Acknowledgements . . . . . . . . . . . . . . . . . . . . . .  14


















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1. 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[1] 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:

      Content-Type: describes the data contained in the body ("the
      content");

      Content-Transfer-Encoding: describes how the content is encoded
      for transmission in an ASCII stream;

      Content-Description: a textual description of the content; and,

      Content-ID: a globally-unique identifier for the content.

   Consult [2] for a list of standard content types. Further, consult
   [3] 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.









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1.1 Requirements

   This package requires:

   o  Tcl/Tk version 8.0.3[4] or later

   In addition, this package requires one of the following:

   o  Trf version 2.0p5[5] or later

   o  base64 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.

1.2 Copyrights

   (c) 1999-2000 Marshall T. Rose

   Hold harmless the author, and any lawful use is allowed.






































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2. SYNTAX

   mime::initialize (Section 3.1) returns a token. Parameters:
       ?-canonical type/subtype
           ?-param    {key value}?...
           ?-encoding value?
           ?-header   {key value}?... ?
       (-file name | -string value | -parts {token1 ... tokenN})

   mime::finalize (Section 3.2) returns an empty string. Parameters:
       token ?-subordinates "all" | "dynamic" | "none"?

   mime::getproperty (Section 3.3) returns a string or a list of
   strings. Parameters:
       token ?property | -names?

   mime::getheader (Section 3.4) returns a list of strings. Parameters:
       token ?key | -names?

   mime::setheader (Section 3.5) returns a list of strings. Parameters:
       token key value ?-mode "write" | "append" | "delete"?

   mime::getbody (Section 3.6) returns a string. Parameters:
       ?-command callback ?-blocksize octets? ?

   mime::copymessage (Section 3.7) returns an empty string. Parameters:
       token channel

   mime::buildmessage (Section 3.7) returns a string. Parameters:
       token

   smtp::sendmessage (Section 3.8) returns a list. Parameters:
       token ?-servers list? ?-ports list?
             ?-queue boolean?     ?-atleastone boolean?
             ?-originator string? ?-recipients string?
             ?-header {key value}?...

   mime::parseaddress (Section 3.9) returns a list of serialized
   arrays. Parameters:
       string

   mime::parsedatetime (Section 3.10) returns a string. Parameters:
       [string | -now] property

   mime::mapencoding (Section 3.10) returns a string. Parameters:
       encoding_name

   mime::reversemapencoding (Section 3.10) returns a string. Parameters:
       charset_type



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3. SEMANTICS

3.1 mime::initialize

   mime::initialize creates a MIME part:

   o  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.

   o  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.

3.2 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".

3.3 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


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   -names is specified, a list of all properties is returned;
   otherwise, a serialized array of properties and values is returned.

3.4 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.

3.5 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:

      write: the key/value is either created or overwritten (the
      default);

      append: a new value is appended for the key (creating it as
      necessary); or,

      delete: all values associated with the key are removed (the
      "value" parameter is ignored).

   Regardless, mime::setheader returns the previous value associated
   with the key.

3.6 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.)


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   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.

3.7 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.

3.7 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.

3.8 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:

      -servers: a list of SMTP servers (the default is "localhost");

      -ports: a list of SMTP ports (the default is 25)

      -queue: indicates that the SMTP server should be asked to queue
      the message for later processing;

      -atleastone: indicates that the SMTP server must find at least
      one recipient acceptable for the message to be sent;

      -originator: a string containing an 822-style address
      specification (if present the header isn't examined for an
      originator address);

      -recipients: a string containing one or more 822-style address
      specifications (if present the header isn't examined for
      recipient addresses); and,

      -header: 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",


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   "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.

3.9 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.














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3.10 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)

3.10 mime::mapencoding

   mime::mapencodings 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.

3.10 mime::reversemapencoding

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
















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4. 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]]





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   # 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







































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References

   [1]  Freed, N. and N.S. Borenstein, "Multipurpose Internet Mail
        Extensions (MIME) Part One: Format of Internet Message Bodies",
        RFC 2045, November 1996.

   [2]  Freed, N. and N.S. Borenstein, "Multipurpose Internet Mail
        Extensions (MIME) Part Two: Media Types", RFC 2046, November
        1995.

   [3]  Crocker, D., "Standard for the format of ARPA Internet Text
        Messages", RFC 822, STD 11, August 1982.

   [4]  http://www.scriptics.com/software/8.1.html

   [5]  http://www.oche.de/~akupries/soft/trf/

   [6]  mailto:dnew@messagemedia.com

   [7]  mailto:a.kupries@westend.com


Author's Address

   Marshall T. Rose
   Dover Beach Consulting, Inc.
   POB 255268
   Sacramento, CA  95865-5268
   US

   Phone: +1 916 483 8878
   Fax:   +1 916 483 8848
   EMail: mrose@dbc.mtview.ca.us


















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Appendix A. TODO List

   mime::initialize

      *  well-defined errorCode values

      *  catch nested errors when processing a multipart












































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Appendix B. Acknowledgements

   This package is influenced by the safe-tcl package (Borenstein and
   Rose, circa 1993), and also by Darren New[6]'s unpublished package
   of 1999.

   This package makes use of Andreas Kupries[7]'s excellent Trf package.












































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