

=head1 NAME

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


=head1 DESCRIPTION

MIME-tools is a collection of Perl5 MIME:: modules for parsing 
and decoding single- or multipart (even nested multipart) MIME 
messages.

=head2 Parsing, in a nutshell

You usually start by creating an instance of B<MIME::Parser> (a subclass
of the abstract B<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 B<MIME::Entity>
object (a subclass of B<Mail::Internet>), which consists of...

=over

=item *

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

=item *

A B<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 B<IO::Handle> interface.  
Most of the MIME:: modules will automatically wrap 
raw (unblessed) filehandles inside B<MIME::IO> objects, so that
they conform to this interface.

=back

Here's a simple example, which reads a MIME stream from STDIN
and outputs all extracted parts to files in the given directory
(and yes, you no longer I<have> to output to files!):

    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; 

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 B<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.  

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


=head2 Composing, in a nutshell

On a small scale, the MIME::Decoder can be used to I<encode> as well.
When encoding an 8-bit document as a 7-bit mail message 
(a no-no, but allowed), the 8-bit characters are escaped for you
into reasonable ASCII sequences, by the B<MIME::Latin1> module.

Here's an example, which composes and sends a MIME 
message containing two parts: a text file, and an attached GIF:

    use MIME::Entity;

    # Create the top-level, and set up the mail headers:
    $top = build MIME::Entity Type=>"multipart/mixed";
    $top->head->add('from',    "me\@myhost.com");
    $top->head->add('to',      "you\@yourhost.com");
    $top->head->add('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";
    
    # Send it:
    open MAIL, "| /usr/lib/sendmail -t -i" or die "open: $!";
    $top->print(\*MAIL);
    close MAIL;

I'm working on making this even easier (in particular, to make it
easier for you to set up the data for each attachment, and to
test the interface with Mail::Send).
I'd also like to make it so that the content-type and encoding
can be automatically inferred from the file's path.


=head1 CPAN SPECIFICATIONS

    Module       DSLI   Description                                 Info
    ----------   ----   ----------------------------------------    ----
    MIME::
    ::Decoder    adpO   OO interface for decoding MIME messages     ERYQ
    ::Entity     adpO   An extracted and decoded MIME entity        ERYQ
    ::Head       adpO   A parsed MIME header                        ERYQ
    ::IO         adpO   Simple I/O handles for filehandles/scalars  ERYQ
    ::Latin1     adpO   Encoding 8-bit Latin-1 as 7-bit ASCII       ERYQ
    ::Parser     adpO   Parses streams to create MIME entities      ERYQ
    ::ParserBase adpO   For building your own MIME parser           ERYQ


=head1 KIT CONTENTS 

    ./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
    ./testin/           files you can use for testing (as in "make test")
    ./testout/          the output of "make test"


=head1 REQUIREMENTS

You'll need B<Perl5.002> or better.

=over 

=item *

It I<might> work with 5.001m+, but you'll need to get ahold of the "vars" 
module.  For this reason, I don't yet "require 5.002" in my modules.

=back

Obtain and install the following kits from the CPAN:

    MIME::QuotedPrint 
    
    MIME::Base64
    
    MailTools:             (1.06 or higher)  
        Mail::Header
        Mail::Internet
        etc...

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


=head1 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)



=head1 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 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.



=head1 DESIGN ISSUES

=over

=item 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 I<header> where I would use I<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, I<and> allow itself to be
initiallized from a MIME::Attrs object.


=item To subclass or not to subclass?

When I originally wrote this module for the CPAN, I agonized for a long
time about whether or not it really should just be a subclass
of B<Mail::Internet> (then at version 1.17).  There were plusses:

=over 4

=item *

Software reuse.

=item *

Inheritance of the mail-sending utilities.

=back

And, unfortunately, minuses:

=over 4

=item *

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.

=item *

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

=item * 

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.

=back


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.

With MailTools now its 1.06 release, it was finally time to finish
what I started, and release MIME-tools 2.0.

=back



=head1 QUESTIONABLE PRACTICES

=over 4

=item Fuzzing of CRLF and newline on input

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

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

=item Fuzzing of CRLF and newline when decoding

The C<"7bit"> and C<"8bit"> decoders will decode both
a C<"\n"> and a C<"\r\n"> end-of-line sequence into a C<"\n">.

The C<"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... I<but this is as it should be>.

=item Fuzzing of CRLF and newline when encoding/composing

All encoders currently output the end-of-line sequence as a C<"\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.

=back



 
=head1 CHANGE LOG

=head2 Current events

=over

=item Version 2.03

Fixed transposed "if" statement, removing spurious printing of header 
from MIME::Parser, and fixing bug in autogenerated filenames.
(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.


=item Version 2.02

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


=item Version 2.01

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

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

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

MIME::Entity can now compose messages.
There were a I<lot> of requestes for this feature.

=back


=head2 Ancient history

=over

=item 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.

=item 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.

=item 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.

=item 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!

=item Version 1.9	

No changes: 1.8 failed CPAN registration

=item Version 1.8.	

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

=back


=head2 Future plans

=over

=item *

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

=item *

Make it even easier to compose and send MIME messages.

=item *

Make VERSION a bit more sensible (2.8, 2.9, 2.10 effective goes
backwards...).

=back




=head1 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.


=head1 SEE ALSO

The MIME format is documented in RFC 1521.  

The MIME header format is documented in RFC 822.



=head1 AUTHOR AND CREDITS

B<MIME-tools was created by:>

Eryq, eryq@rhine.gsfc.nasa.gov

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

B<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
	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 have been
invaluable in improving the whole:

	Phil Abercrombie  
	Andrew Pimlott    
	Joel Noble        
	Russell Sutherland
	Larry Virden

Please forgive me if I've left you out.  Or email me.

=cut





