MIME-tools

Home | MIME::Body | MIME::Decoder | MIME::Entity | MIME::Head
MIME::IO | MIME::Latin1 | MIME::Parser | MIME::ParserBase
MIME::ToolUtils

# MIME-tools It's MIME time! | NAME SYNOPSIS DESCRIPTION A QUICK TOUR Parsing, in a nutshell Composing, in a nutshell Other stuff CONTENTS Modules in this toolkit Programs in this toolkit MANIFEST REQUIREMENTS INSTALLATION NOTES Compatibility Design issues Questionable practices CHANGE LOG Current events Ancient history Future plans TERMS AND CONDITIONS SUPPORT AUTHOR ACKNOWLEDGMENTS SEE ALSO

## NAME

MIME-tools - modules for parsing (and creating!) MIME entities

## SYNOPSIS

Here's some pretty basic code for parsing a MIME message, and outputting its decoded components to a given directory:

        use MIME::Parser;

        # Create parser, and set the output directory:
        my $parser = new MIME::Parser;
        $parser->output_dir("$ENV{HOME}/mimemail");

        # Parse input:
        $entity = $parser->read(\*STDIN) or die "couldn't parse MIME stream";

        # Take a look at the top-level entity (and any parts it has):
        $entity->dump_skeleton;

Here's some code which composes and sends a MIME message containing three parts: a text file, an attached GIF, and some more text:

        use MIME::Entity;

        # Create the top-level, and set up the mail headers:
        $top = build MIME::Entity Type   =>"multipart/mixed",
                                  -From    => "me\@myhost.com",
    	                      -To      => "you\@yourhost.com",
                                  -Subject => "Hello, nurse!";

        # Attachment #1: a simple text document:
        attach $top  Path=>"./testin/short.txt";

        # Attachment #2: a GIF file:
        attach $top  Path        => "./docs/mime-sm.gif",
                     Type        => "image/gif",
                     Encoding    => "base64";

        # Attachment #3: some literal text:
        attach $top  Data=>$message;

        # Send it:
        open MAIL, "| /usr/lib/sendmail -t -i" or die "open: $!";
        $top->print(\*MAIL);
        close MAIL;

## DESCRIPTION

MIME-tools is a collection of Perl5 MIME:: modules for parsing, decoding, and generating single- or multipart (even nested multipart) MIME messages. (Yes, kids, that means you can send messages with attached GIF files).

## A QUICK TOUR

### Parsing, in a nutshell

You usually start by creating an instance of MIME::Parser (a subclass of the abstract MIME::ParserBase ), and setting up certain parsing parameters: what directory to save extracted files to, how to name the files, etc.

You then give that instance a readable filehandle on which waits a MIME message. If all goes well, you will get back a MIME::Entity object (a subclass of Mail::Internet ), which consists of...

- A MIME::Head (a subclass of Mail::Header ) which holds the MIME header data.

- A MIME::Body , which is a object that knows where the body data is. You ask this object to ``open'' itself for reading, and it will hand you back an ``I/O handle'' for reading the data: this is a FileHandle-like object, and could be of any class, so long as it conforms to a subset of the IO::Handle interface.

If the original message was a multipart document, the MIME::Entity object will have a non-empty list of ``parts'', each of which is in turn a MIME::Entity (which might also be a multipart entity, etc, etc...).

Internally, the parser (in MIME::ParserBase) asks for instances of MIME::Decoder whenever it needs to decode an encoded file. MIME::Decoder has a mapping from supported encodings (e.g., 'base64') to classes whose instances can decode them. You can add to this mapping to try out new/experiment encodings. You can also use MIME::Decoder by itself.

### Composing, in a nutshell

On a small scale, the MIME::Decoder can be used to encode as well. All the standard encodings are supported:

        7bit               Use this for plain ASCII documents (and multiparts)
        8bit
        binary
        quoted-printable   Use this for text files with 8-bit characters
        base64             Use this for binary files

When encoding a text document as a `7bit` mail message, the software will not puke on 8-bit characters... instead, the 8-bit characters are escaped for you into reasonable ASCII sequences, by the MIME::Latin1 module. This feature is for folks who really hate sending out a document as quoted-printable just because it happens to have a couple of French or German names.

I've considered making it so that the content-type and encoding can be automatically inferred from the file's path, but that seems to be asking for trouble... or at least, for Mail::Cap...

### Other stuff

If you want to tweak the way this toolkit works (for example, to turn on debugging), use the routines in the MIME::ToolUtils module.

## CONTENTS

### Modules in this toolkit

        Module       DSLI   Description                                  Info
        ----------   ----   ------------------------------------------   ----
        MIME::
        ::Body       adpO   Abstract message holder (file, scalar, etc.) ERYQ
        ::Decoder    bdpO   OO interface for decoding MIME messages      ERYQ
        ::Entity     bdpO   An extracted and decoded MIME entity         ERYQ
        ::Field::*   bdpO   Mail::Field subclasses for parsing fields    ERYQ
        ::Head       bdpO   A parsed MIME header (Mail::Header subclass) ERYQ
        ::IO         adpO   Simple I/O handles for filehandles/scalars   ERYQ
        ::Latin1     adpO   Encoding 8-bit Latin-1 as 7-bit ASCII        ERYQ
        ::Parser     bdpO   Parses streams to create MIME entities       ERYQ
        ::ParserBase bdpO   For building your own MIME parser            ERYQ
        ::ToolUtils  adpO   For tweaking the MIME-tools library          ERYQ

### Programs in this toolkit

        mimedump    - dump out a summary of the contents of a MIME message
        mimeexplode - parse/decode a MIME message into its component files
        mimesend    - send a message with attachments from the command line

## MANIFEST

        ./MIME/*.pm         the MIME-tools classes
        ./Makefile.PL       the input to MakeMaker
        ./COPYING           terms and conditions for copying/using the software
        ./README            this file
        ./docs/             HTMLized documentation
        ./etc/              convenient copies of other modules you may need
        ./examples          sample executables
        ./t/*.t             the "make test" scripts
        ./testin/           files you can use for testing (as in "make test")
        ./testout/          the output of "make test"

## REQUIREMENTS

You'll need Perl5.002 or better.

You'll need to obtain and install the following kits from the CPAN:

MIME::(QuotedPrint, Base64)
  These perform the low-level MIME decoding. Get these from Gisle Aas' author directory. They are also reported to be in the LWP distribution.

MailTools (1.06 or higher)
  This is Graham Barr's revamped set of Mail:: modules. Many of them are now superclasses of the MIME:: modules, and perform the core functionality of manipulating headers and fields.

For your convenience, possibly-old copies of the MIME:: modules are provided in the ./etc directory, of the distribution, but they are NOT installed for you during the installation procedure.

## INSTALLATION

Pretty simple:

        1. Gunzip and de-tar the distribution, and cd to the top level.
        2. Type:      perl Makefile.PL
        3. Type:      make                    # this step is optional
        4. Type:      make test               # this step is optional
        5. Type:      make install

Other interesting targets in the Makefile are:

        make config     # to check if the Makefile is up-to-date
        make clean      # delete local temp files (Makefile gets renamed)
        make realclean  # delete derived files (including ./blib)

If you're installing this as a replacment for MIME-parser 1.x or earlier, please read the Compatibility notes.

## NOTES

### Compatibility

If you're installing this as a replacement for the MIME-parser 1.x release, and you really don't want to break existing code, you should do this at any point before the parsing code is invoked:

        use MIME::ToolUtils;

        MIME::ToolUtils->emulate_version(1.0);

Try not to get too attached to this, though. Instead, plan on upgrading your code ASAP to the 2.0 style.

### Design issues

Why assume that MIME objects are email objects?
  I quote from Achim Bohnet, who gave feedback on v.1.9 (I think he's using the word header where I would use field ; e.g., to refer to ``Subject:'', ``Content-type:'', etc.):

          There is also IMHO no requirement [for] MIME::Heads to look
          like [email] headers; so to speak, the MIME::Head [simply stores]
          the attributes of a complex object, e.g.:

              new MIME::Head type => "text/plain",
                             charset => ...,
                             disposition => ..., ... ;

  I agree in principle, but (alas and dammit) RFC-1521 says otherwise. RFC-1521 [MIME] headers are a syntactic subset of RFC-822 [email] headers. Perhaps a better name for these modules would be RFC1521:: instead of MIME::, but we're a little beyond that stage now.

  However, in my mind's eye, I see an abstract class, call it MIME::Attrs, which does what Achim suggests... so you could say:

           my $attrs = new MIME::Attrs type => "text/plain",
      				 charset => ...,
                                       disposition => ..., ... ;

  We could even make it a superclass of MIME::Head: that way, MIME::Head would have to implement its interface, and allow itself to be initiallized from a MIME::Attrs object.

To subclass or not to subclass?
  When I originally wrote these modules for the CPAN, I agonized for a long time about whether or not they really should subclass from Mail::Internet (then at version 1.17). There were plusses:

  - Software reuse.

  - Inheritance of the mail-sending utilities.

  And, unfortunately, minuses:

  - The Mail::Internet 1.17 model of messages as being short enough to fit into in-core arrays is excellent for most email applications; however, it seemed ill-suited for generic MIME applications, where MIME streams could be megabytes long.

  - The implementation of Mail::Internet 1.17 was excellent for certain kinds of header manipulation, but the implementation of `get()` was less-efficient than I would have liked for MIME applications.

  - In my heart of hearts, I honestly felt that the head should be encapsulated as a first-class object, and in Mail::Internet 1.17 it was not.

  So I chose to make MIME::Head and MIME::Entity their own standalone modules.

  Since that time, I worked with Graham Barr (author of most of the MailTools package, and a darn nice guy to ``work'' with over email), and he has graciously evolved the MailTools modules into a direction that addressed a lot of these issues.

  When MailTools hit its 1.06 release, it was finally time to finish what I had started, and release MIME-tools 2.0. We now are almost at the stage of a fully-integrated Mail/MIME environment.

### Questionable practices

Fuzzing of CRLF and newline on input
  RFC-1521 dictates that MIME streams have lines terminated by CRLF (`"\r\n"`). However, it is extremely likely that folks will want to parse MIME streams where each line ends in the local newline character `"\n"` instead.

  An attempt has been made to allow the parser to handle both CRLF and newline-terminated input.

  See MIME::ParserBase for details.

Fuzzing of CRLF and newline when decoding
  The `"7bit"` and `"8bit"` decoders will decode both a `"\n"` and a `"\r\n"` end-of-line sequence into a `"\n"`.

  The `"binary"` decoder (default if no encoding specified) still outputs stuff verbatim... so a MIME message with CRLFs and no explicit encoding will be output as a text file that, on many systems, will have an annoying ^M at the end of each line... but this is as it should be .

  See MIME::ParserBase for details.

Fuzzing of CRLF and newline when encoding/composing
  All encoders currently output the end-of-line sequence as a `"\n"`, with the assumption that the local mail agent will perform the conversion from newline to CRLF when sending the mail.

  However, there probably should be an option to output CRLF as per RFC-1521. I'm currently working on a good mechanism for this.

  See MIME::ParserBase for details.

Inability to handle multipart boundaries with embedded newlines
  First, let's get something straight: this is an evil, EVIL practice. If your mailer creates multipart boundary strings that contain newlines, give it two weeks notice and find another one. If your mail robot receives MIME mail like this, regard it as syntactically incorrect, which it is.

  See MIME::ParserBase for details.

## CHANGE LOG

### Current events

Version 2.13
  New features
    Added RFC-1522-style decoding of encoded header fields. Header decoding can now be done automatically during parsing via the new `decode()` method in MIME::Head... just tell your parser object that you want to `decode_headers()`. Thanks to Kent Boortz for providing the idea, and the baseline RFC-1522-decoding code!

    Building MIME messages is even easier. Now, when you use MIME::Entity's `build()` or `attach()`, you can also supply individual mail headers to set (e.g., `-Subject`, `-From`, `-To`).

    Added `Disposition` to MIME::Entity's `build()` method. Thanks to Kurt Freytag for suggesting this feature.

    An `X-Mailer` header is now output by default in all MIME-Entity-prepared messages, so any bad MIME we generate can be traced back to this toolkit.

    Added `purge()` method to MIME::Entity for deleteing leftover files. Thanks to Jason L. Tibbitts III for suggesting this feature.

    Added `seek()` and `tell()` methods to built-in MIME::IO classes. Only guaranteed to work when reading! Thanks to Jason L. Tibbitts III for suggesting this feature.

    When parsing a multipart message with apparently no boundaries, the error message you get has been improved. Thanks to Andreas Koenig for suggesting this.

  Bug fixes
    Patched over a Perl 5.002 (and maybe earlier and later) bug involving FileHandle::new_tmpfile. It seems that the underlying filehandles were not being closed when the FileHandle objects went out of scope! There is now an internal routine that creates true FileHandle objects for anonymous temp files. Thanks to Dragomir R. Radev and Zyx for reporting the weird behavior that led to the discovery of this bug.

    MIME::Entity's `build()` method now warns you if you give it an illegal boundary string, and substitutes one of its own.

    MIME::Entity's `build()` method now generates safer, fully-RFC-1521-compliant boundary strings.

    Bug in MIME::Decoder's `install()` method was fixed. Thanks to Rolf Nelson and Nickolay Saukh for finding this.

    Changed FileHandle::new_tmpfile to FileHandle->new_tmpfile, so some Perl installations will be happier. Thanks to Larry W. Virden for finding this bug.

    Gave `=over` an arg of 4 in all PODs. Thanks to Larry W. Virden for pointing out the problems of bare =over's

Version 2.04
  A bug in MIME::Entity's output method was corrected. MIME::Entity::print now outputs everything to the desired filehandle explicitly. Thanks to Jake Morrison for pointing out the incompatibility with Mail::Header.

Version 2.03
  Fixed bug in autogenerated filenames resulting from transposed ``if'' statement in MIME::Parser, removing spurious printing of header as well. (Annoyingly, this bug is invisible if debugging is turned on!) Thanks to Andreas Koenig for bringing this to my attention.

  Fixed bug in MIME::Entity::body() where it was using the bodyhandle completely incorrectly. Thanks to Joel Noble for bringing this to my attention.

  Fixed MIME::Head::VERSION so CPAN:: is happier. Thanks to Larry Virden for bringing this to my attention.

  Fixed undefined-variable warnings when dumping skeleton (happened when there was no Subject: line) Thanks to Joel Noble for bringing this to my attention.

Version 2.02
  Stupid, stupid bugs in both BASE64 encoding and decoding were fixed. Thanks to Phil Abercrombie for locating them.

Version 2.01
  Modules now inherit from the new Mail:: modules! This means big changes in behavior.

  MIME::Parser can now store message data in-core. There were a lot of requests for this feature.

  MIME::Entity can now compose messages. There were a lot of requests for this feature.

  Added option to parse `"message/rfc822"` as a pseduo-multipart document. Thanks to Andreas Koenig for suggesting this.

### Ancient history

Version 1.13
  MIME::Head now no longer requires space after ``:'', although either a space or a tab after the ``:'' will be swallowed if there. Thanks to Igor Starovoitov for pointing out this shortcoming.

Version 1.12
  Fixed bugs in parser where CRLF-terminated lines were blowing out the handling of preambles/epilogues. Thanks to Russell Sutherland for reporting this bug.

  Fixed idiotic `is_multipart()` bug. Thanks to Andreas Koenig for noticing it.

  Added untested `binmode()` calls to parser for DOS, etc. systems. No idea if this will work...

  Reorganized the `output_path()` methods to allow easy use of inheritance, as per Achim Bohnet's suggestion.

  Changed MIME::Head to report mime_type more accurately.

  POSIX module no longer loaded by Parser if perl >= 5.002. Hey, 5.001'ers: let me know if this breaks stuff, okay?

  Added unsupported ./examples directory.

Version 1.11
  Converted over to using Makefile.PL. Thanks to Andreas Koenig for the much-needed kick in the pants...

  Added t/*.t files for testing. Eeeeeeeeeeeh...it's a start.

  Fixed bug in default parsing routine for generating output paths; it was warning about evil filenames if there simply were no recommended filenames. D'oh!

  Fixed redefined `parts()` method in Entity.

  Fixed bugs in Head where field name wasn't being case folded.

Version 1.10
  A typo was causing the epilogue of an inner multipart message to be swallowed to the end of the OUTER multipart message; this has now been fixed. Thanks to Igor Starovoitov for reporting this bug.

  A bad regexp for parameter names was causing some parameters to be parsed incorrectly; this has also been fixed. Thanks again to Igor Starovoitov for reporting this bug. It is now possible to get full control of the filenaming algorithm before output files are generated, and the default algorithm is safer. Thanks to Laurent Amon for pointing out the problems, and suggesting some solutions.

  Fixed illegal ``simple'' multipart test file. D'OH!

Version 1.9
  No changes: 1.8 failed CPAN registration

Version 1.8.
  Fixed incompatibility with 5.001 and FileHandle::new_tmpfile Added COPYING file, and improved README.

### Future plans

- Dress up mimedump and mimeexplode utilities to take cmd line options for directory, environment vars (MIMEDUMP_OUTPUT, etc.).

- Make it even easier to compose and send MIME messages.

- Make VERSIONs a bit more sensible (e.g., 2.8, 2.9, 2.10 effectively goes backwards...).

## TERMS AND CONDITIONS

Copyright (c) 1996 by Eryq. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See the COPYING file in the distribution for details.

## SUPPORT

Please email me directly with questions/problems (see AUTHOR below).

## AUTHOR

MIME-tools was created by:

        ___  _ _ _   _  ___ _
       / _ \| '_| | | |/ _ ' /    Eryq
      |  __/| | | |_| | |_| |     http://www.mcs.net/~eryq
       \___||_|  \__, |\__, |__   eryq@enteract.com
                 |___/    |___/   eryq@rhine.gsfc.nasa.gov

Initial release (1.0): 28 April 1996. Re-release (2.0): Halloween 1996.

## ACKNOWLEDGMENTS

This kit would not have been possible but for the direct contributions of the following:

        Gisle Aas          The MIME encoding/decoding modules
        Laurent Amon       Bug reports and suggestions
        Graham Barr        The new MailTools
        Achim Bohnet       Numerous good suggestions, including the I/O model
        Kent Boortz        Initial code for RFC-1522-decoding of MIME headers
        Andreas Koenig     Numerous good ideas, tons of beta testing,
                           and help with CPAN-friendly packaging
        Igor Starovoitov   Bug reports and suggestions

    Not to mention the Accidental Beta Test Team, whose bug reports (and
    comments) have been invaluable in improving the whole:

        Phil Abercrombie
        Kurt Freytag
        Jake Morrison
        Rolf Nelson
        Joel Noble
        Andrew Pimlott
        Dragomir R. Radev
        Nickolay Saukh
        Russell Sutherland
        Larry Virden
        Zyx

Please forgive me if I've accidentally left you out. Better yet, email me, and I'll put you in.

## SEE ALSO

Users of this toolkit may wish to read the documentation of Mail::Header and Mail::Internet.

The MIME format is documented in RFCs 1521-1522, and more recently in RFCs 2045-2049.

The MIME header format is an outgrowth of the mail header format documented in RFC 822.