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MIME::Entity(3)
NAME
MIME::Entity - class for parsed-and-decoded MIME message
SYNOPSIS
Before reading further, you should see MIME::Tools to make sure that you
understand where this module fits into the grand scheme of things. Go on,
do it now. I'll wait.
Ready? Ok...
### Create an entity:
$top = MIME::Entity->build(From => 'me@myhost.com',
To => 'you@yourhost.com',
Subject => "Hello, nurse!",
Data => \@my_message);
### Attach stuff to it:
$top->attach(Path => $gif_path,
Type => "image/gif",
Encoding => "base64");
### Sign it:
$top->sign;
### Output it:
$top->print(\*STDOUT);
DESCRIPTION
A subclass of Mail::Internet.
This package provides a class for representing MIME message entities, as
specified in RFC 1521, Multipurpose Internet Mail Extensions.
EXAMPLES
Construction examples
Create a document for an ordinary 7-bit ASCII text file (lots of stuff is
defaulted for us):
$ent = MIME::Entity->build(Path=>"english-msg.txt");
Create a document for a text file with 8-bit (Latin-1) characters:
$ent = MIME::Entity->build(Path =>"french-msg.txt",
Encoding =>"quoted-printable",
From =>'jean.luc@inria.fr',
Subject =>"C'est bon!");
Create a document for a GIF file (the description is completely optional;
note that we have to specify content-type and encoding since they're not
the default values):
$ent = MIME::Entity->build(Description => "A pretty picture",
Path => "./docs/mime-sm.gif",
Type => "image/gif",
Encoding => "base64");
Create a document that you already have the text for, using "Data":
$ent = MIME::Entity->build(Type => "text/plain",
Encoding => "quoted-printable",
Data => ["First line.\n",
"Second line.\n",
"Last line.\n"]);
Create a multipart message, with the entire structure given explicitly:
### Create the top-level, and set up the mail headers:
$top = MIME::Entity->build(Type => "multipart/mixed",
From => 'me@myhost.com',
To => 'you@yourhost.com',
Subject => "Hello, nurse!");
### Attachment #1: a simple text document:
$top->attach(Path=>"./testin/short.txt");
### Attachment #2: a GIF file:
$top->attach(Path => "./docs/mime-sm.gif",
Type => "image/gif",
Encoding => "base64");
### Attachment #3: text we'll create with text we have on-hand:
$top->attach(Data => $contents);
Suppose you don't know ahead of time that you'll have attachments? No
problem: you can "attach" to singleparts as well:
$top = MIME::Entity->build(From => 'me@myhost.com',
To => 'you@yourhost.com',
Subject => "Hello, nurse!",
Data => \@my_message);
if ($GIF_path) {
$top->attach(Path => $GIF_path,
Type => 'image/gif');
}
Copy an entity (headers, parts... everything but external body data):
my $deepcopy = $top->dup;
Access examples
### Get the head, a MIME::Head:
$head = $ent->head;
### Get the body, as a MIME::Body;
$bodyh = $ent->bodyhandle;
### Get the intended MIME type (as declared in the header):
$type = $ent->mime_type;
### Get the effective MIME type (in case decoding failed):
$eff_type = $ent->effective_type;
### Get preamble, parts, and epilogue:
$preamble = $ent->preamble; ### ref to array of lines
$num_parts = $ent->parts;
$first_part = $ent->parts(0); ### an entity
$epilogue = $ent->epilogue; ### ref to array of lines
Manipulation examples
Muck about with the body data:
### Read the (unencoded) body data:
if ($io = $ent->open("r")) {
while (defined($_ = $io->getline)) { print $_ }
$io->close;
}
### Write the (unencoded) body data:
if ($io = $ent->open("w")) {
foreach (@lines) { $io->print($_) }
$io->close;
}
### Delete the files for any external (on-disk) data:
$ent->purge;
Muck about with the signature:
### Sign it (automatically removes any existing signature):
$top->sign(File=>"$ENV{HOME}/.signature");
### Remove any signature within 15 lines of the end:
$top->remove_sig(15);
Muck about with the headers:
### Compute content-lengths for singleparts based on bodies:
### (Do this right before you print!)
$entity->sync_headers(Length=>'COMPUTE');
Muck about with the structure:
### If a 0- or 1-part multipart, collapse to a singlepart:
$top->make_singlepart;
### If a singlepart, inflate to a multipart with 1 part:
$top->make_multipart;
Delete parts:
### Delete some parts of a multipart message:
my @keep = grep { keep_part($_) } $msg->parts;
$msg->parts(\@keep);
Output examples
Print to filehandles:
### Print the entire message:
$top->print(\*STDOUT);
### Print just the header:
$top->print_header(\*STDOUT);
### Print just the (encoded) body... includes parts as well!
$top->print_body(\*STDOUT);
Stringify... note that "stringify_xx" can also be written "xx_as_string";
the methods are synonymous, and neither form will be deprecated:
### Stringify the entire message:
print $top->stringify; ### or $top->as_string
### Stringify just the header:
print $top->stringify_header; ### or $top->header_as_string
### Stringify just the (encoded) body... includes parts as well!
print $top->stringify_body; ### or $top->body_as_string
Debug:
### Output debugging info:
$entity->dump_skeleton(\*STDERR);
PUBLIC INTERFACE
Construction
new [SOURCE]
Class method. Create a new, empty MIME entity. Basically, this uses
the Mail::Internet constructor...
If SOURCE is an ARRAYREF, it is assumed to be an array of lines that
will be used to create both the header and an in-core body.
Else, if SOURCE is defined, it is assumed to be a filehandle from which
the header and in-core body is to be read.
Note: in either case, the body will not be parsed: merely read!
add_part ENTITY, [OFFSET]
Instance method. Assuming we are a multipart message, add a body part
(a MIME::Entity) to the array of body parts. Returns the part that was
just added.
If OFFSET is positive, the new part is added at that offset from the
beginning of the array of parts. If it is negative, it counts from the
end of the array. (An INDEX of -1 will place the new part at the very
end of the array, -2 will place it as the penultimate item in the
array, etc.) If OFFSET is not given, the new part is added to the end
of the array. Thanks to Jason L Tibbitts III for providing support for
OFFSET.
Warning: in general, you only want to attach parts to entities with a
content-type of "multipart/*").
attach PARAMHASH
Instance method. The real quick-and-easy way to create multipart
messages. The PARAMHASH is used to "build" a new entity; this method
is basically equivalent to:
$entity->add_part(ref($entity)->build(PARAMHASH, Top=>0));
Note: normally, you attach to multipart entities; however, if you
attach something to a singlepart (like attaching a GIF to a text
message), the singlepart will be coerced into a multipart
automatically.
build PARAMHASH
Class/instance method. A quick-and-easy catch-all way to create an
entity. Use it like this to build a "normal" single-part entity:
$ent = MIME::Entity->build(Type => "image/gif",
Encoding => "base64",
Path => "/path/to/xyz12345.gif",
Filename => "saveme.gif",
Disposition => "attachment");
And like this to build a "multipart" entity:
$ent = MIME::Entity->build(Type => "multipart/mixed",
Boundary => "---1234567");
A minimal MIME header will be created. If you want to add or modify
any header fields afterwards, you can of course do so via the
underlying head object... but hey, there's now a prettier syntax!
$ent = MIME::Entity->build(Type =>"multipart/mixed",
From => $myaddr,
Subject => "Hi!",
'X-Certified' => ['SINED',
'SEELED',
'DELIVERED']);
Normally, an "X-Mailer" header field is output which contains this
toolkit's name and version (plus this module's RCS version). This will
allow any bad MIME we generate to be traced back to us. You can of
course overwrite that header with your own:
$ent = MIME::Entity->build(Type => "multipart/mixed",
'X-Mailer' => "myprog 1.1");
Or remove it entirely:
$ent = MIME::Entity->build(Type => "multipart/mixed",
'X-Mailer' => undef);
OK, enough hype. The parameters are:
(FIELDNAME)
Any field you want placed in the message header, taken from the
standard list of header fields (you don't need to worry about
case):
Bcc Encrypted Received Sender
Cc From References Subject
Comments Keywords Reply-To To
Content-* Message-ID Resent-* X-*
Date MIME-Version Return-Path
Organization
To give experienced users some veto power, these fields will be set
after the ones I set... so be careful: don't set any MIME fields
(like "Content-type") unless you know what you're doing!
To specify a fieldname that's not in the above list, even one
that's identical to an option below, just give it with a trailing
":", like "My-field:". When in doubt, that always signals a mail
field (and it sort of looks like one too).
Boundary
Multipart entities only. Optional. The boundary string. As per
RFC-1521, it must consist only of the characters
"[0-9a-zA-Z'()+_,-./:=?]" and space (you'll be warned, and your
boundary will be ignored, if this is not the case). If you omit
this, a random string will be chosen... which is probably safer.
Charset
Optional. The character set.
Data
Single-part entities only. Optional. An alternative to Path (q.v.):
the actual data, either as a scalar or an array reference (whose
elements are joined together to make the actual scalar). The body
is opened on the data using MIME::Body::InCore.
Description
Optional. The text of the content-description. If you don't specify
it, the field is not put in the header.
Disposition
Optional. The basic content-disposition ("attachment" or "inline").
If you don't specify it, it defaults to "inline" for backwards
compatibility. Thanks to Kurt Freytag for suggesting this feature.
Encoding
Optional. The content-transfer-encoding. If you don't specify it,
a reasonable default is put in. You can also give the special
value '-SUGGEST', to have it chosen for you in a heavy-duty fashion
which scans the data itself.
Filename
Single-part entities only. Optional. The recommended filename.
Overrides any name extracted from "Path". The information is
stored both the deprecated (content-type) and preferred
(content-disposition) locations. If you explicitly want to avoid a
recommended filename (even when Path is used), supply this as empty
or undef.
Id Optional. Set the content-id.
Path
Single-part entities only. Optional. The path to the file to
attach. The body is opened on that file using MIME::Body::File.
Top Optional. Is this a top-level entity? If so, it must sport a
MIME-Version. The default is true. (NB: look at how "attach()"
uses it.)
Type
Optional. The basic content-type ("text/plain", etc.). If you don't
specify it, it defaults to "text/plain" as per RFC-1521. Do
yourself a favor: put it in.
dup Instance method. Duplicate the entity. Does a deep, recursive copy,
but beware: external data in bodyhandles is not copied to new files!
Changing the data in one entity's data file, or purging that entity,
will affect its duplicate. Entities with in-core data probably need
not worry.
Access
body [VALUE]
Instance method. Get the encoded (transport-ready) body, as an array of
lines. This is a read-only data structure: changing its contents will
have no effect. Its contents are identical to what is printed by
print_body().
Provided for compatibility with Mail::Internet, so that methods like
"smtpsend()" will work. Note however that if VALUE is given, a fatal
exception is thrown, since you cannot use this method to set the lines
of the encoded message.
If you want the raw (unencoded) body data, use the bodyhandle() method
to get and use a MIME::Body. The content-type of the entity will tell
you whether that body is best read as text (via getline()) or raw data
(via read()).
bodyhandle [VALUE]
Instance method. Get or set an abstract object representing the body of
the message. The body holds the decoded message data.
Note that not all entities have bodies! An entity will have either a
body or parts: not both. This method will only return an object if
this entity can have a body; otherwise, it will return undefined.
Whether-or-not a given entity can have a body is determined by (1) its
content type, and (2) whether-or-not the parser was told to extract
nested messages:
Type: | Extract nested? | bodyhandle() | parts()
-----------------------------------------------------------------------
multipart/* | - | undef | 0 or more MIME::Entity
message/* | true | undef | 0 or 1 MIME::Entity
message/* | false | MIME::Body | empty list
(other) | - | MIME::Body | empty list
If "VALUE" is not given, the current bodyhandle is returned, or undef
if the entity cannot have a body.
If "VALUE" is given, the bodyhandle is set to the new value, and the
previous value is returned.
See "parts" for more info.
effective_type [MIMETYPE]
Instance method. Set/get the effective MIME type of this entity. This
is usually identical to the actual (or defaulted) MIME type, but in
some cases it differs. For example, from RFC-2045:
Any entity with an unrecognized Content-Transfer-Encoding must be
treated as if it has a Content-Type of "application/octet-stream",
regardless of what the Content-Type header field actually says.
Why? because if we can't decode the message, then we have to take the
bytes as-is, in their (unrecognized) encoded form. So the message
ceases to be a "text/foobar" and becomes a bunch of undecipherable
bytes -- in other words, an "application/octet-stream".
Such an entity, if parsed, would have its effective_type() set to
"application/octet_stream", although the mime_type() and the contents
of the header would remain the same.
If there is no effective type, the method just returns what mime_type()
would.
Warning: the effective type is "sticky"; once set, that
effective_type() will always be returned even if the conditions that
necessitated setting the effective type become no longer true.
epilogue [LINES]
Instance method. Get/set the text of the epilogue, as an array of
newline-terminated LINES. Returns a reference to the array of lines,
or undef if no epilogue exists.
If there is a epilogue, it is output when printing this entity;
otherwise, a default epilogue is used. Setting the epilogue to undef
(not []!) causes it to fallback to the default.
head [VALUE]
Instance method. Get/set the head.
If there is no VALUE given, returns the current head. If none exists,
an empty instance of MIME::Head is created, set, and returned.
Note: This is a patch over a problem in Mail::Internet, which doesn't
provide a method for setting the head to some given object.
is_multipart
Instance method. Does this entity's effective MIME type indicate that
it's a multipart entity? Returns undef (false) if the answer couldn't
be determined, 0 (false) if it was determined to be false, and true
otherwise. Note that this says nothing about whether or not parts were
extracted.
NOTE: we switched to effective_type so that multiparts with bad or
missing boundaries could be coerced to an effective type of
"application/x-unparseable-multipart".
mime_type
Instance method. A purely-for-convenience method. This simply relays
the request to the associated MIME::Head object. If there is no head,
returns undef in a scalar context and the empty array in a list
context.
Before you use this, consider using effective_type() instead,
especially if you obtained the entity from a MIME::Parser.
open READWRITE
Instance method. A purely-for-convenience method. This simply relays
the request to the associated MIME::Body object (see
MIME::Body::open()). READWRITE is either 'r' (open for read) or 'w'
(open for write).
If there is no body, returns false.
parts
parts INDEX
parts ARRAYREF
Instance method. Return the MIME::Entity objects which are the sub
parts of this entity (if any).
If no argument is given, returns the array of all sub parts, returning
the empty array if there are none (e.g., if this is a single part
message, or a degenerate multipart). In a scalar context, this returns
you the number of parts.
If an integer INDEX is given, return the INDEXed part, or undef if it
doesn't exist.
If an ARRAYREF to an array of parts is given, then this method sets the
parts to a copy of that array, and returns the parts. This can be used
to delete parts, as follows:
### Delete some parts of a multipart message:
$msg->parts([ grep { keep_part($_) } $msg->parts ]);
Note: for multipart messages, the preamble and epilogue are not
considered parts. If you need them, use the "preamble()" and
"epilogue()" methods.
Note: there are ways of parsing with a MIME::Parser which cause certain
message parts (such as those of type "message/rfc822") to be "reparsed"
into pseudo-multipart entities. You should read the documentation for
those options carefully: it is possible for a diddled entity to not be
multipart, but still have parts attached to it!
See "bodyhandle" for a discussion of parts vs. bodies.
parts_DFS
Instance method. Return the list of all MIME::Entity objects included
in the entity, starting with the entity itself, in depth-first-search
order. If the entity has no parts, it alone will be returned.
Thanks to Xavier Armengou for suggesting this method.
preamble [LINES]
Instance method. Get/set the text of the preamble, as an array of
newline-terminated LINES. Returns a reference to the array of lines,
or undef if no preamble exists (e.g., if this is a single-part entity).
If there is a preamble, it is output when printing this entity;
otherwise, a default preamble is used. Setting the preamble to undef
(not []!) causes it to fallback to the default.
Manipulation
make_multipart [SUBTYPE], OPTSHASH...
Instance method. Force the entity to be a multipart, if it isn't
already. We do this by replacing the original [singlepart] entity with
a new multipart that has the same non-MIME headers ("From", "Subject",
etc.), but all-new MIME headers ("Content-type", etc.). We then create
a copy of the original singlepart, strip out the non-MIME headers from
that, and make it a part of the new multipart. So this:
From: me
To: you
Content-type: text/plain
Content-length: 12
Hello there!
Becomes something like this:
From: me
To: you
Content-type: multipart/mixed; boundary="----abc----"
------abc----
Content-type: text/plain
Content-length: 12
Hello there!
------abc------
The actual type of the new top-level multipart will be
"multipart/SUBTYPE" (default SUBTYPE is "mixed").
Returns 'DONE' if we really did inflate a singlepart to a multipart.
Returns 'ALREADY' (and does nothing) if entity is already multipart and
Force was not chosen.
If OPTSHASH contains Force=>1, then we always bump the top-level's
content and content-headers down to a subpart of this entity, even if
this entity is already a multipart. This is apparently of use to
people who are tweaking messages after parsing them.
make_singlepart
Instance method. If the entity is a multipart message with one part,
this tries hard to rewrite it as a singlepart, by replacing the content
(and content headers) of the top level with those of the part. Also
crunches 0-part multiparts into singleparts.
Returns 'DONE' if we really did collapse a multipart to a
singlepart. Returns 'ALREADY' (and does nothing) if entity is already
a singlepart. Returns '0' (and does nothing) if it can't be made
into a singlepart.
purge
Instance method. Recursively purge (e.g., unlink) all external (e.g.,
on-disk) body parts in this message. See MIME::Body::purge() for
details.
Note: this does not delete the directories that those body parts are
contained in; only the actual message data files are deleted. This is
because some parsers may be customized to create intermediate
directories while others are not, and it's impossible for this class to
know what directories are safe to remove. Only your application
program truly knows that.
If you really want to "clean everything up", one good way is to use
"MIME::Parser::file_under()", and then do this before parsing your next
message:
$parser->filer->purge();
I wouldn't attempt to read those body files after you do this, for
obvious reasons. As of MIME-tools 4.x, each body's path is undefined
after this operation. I warned you I might do this; truly I did.
Thanks to Jason L. Tibbitts III for suggesting this method.
remove_sig [NLINES]
Instance method, override. Attempts to remove a user's signature from
the body of a message.
It does this by looking for a line matching "/^-- $/" within the last
"NLINES" of the message. If found then that line and all lines after
it will be removed. If "NLINES" is not given, a default value of 10
will be used. This would be of most use in auto-reply scripts.
For MIME entity, this method is reasonably cautious: it will only
attempt to un-sign a message with a content-type of "text/*".
If you send remove_sig() to a multipart entity, it will relay it to the
first part (the others usually being the "attachments").
Warning: currently slurps the whole message-part into core as an array
of lines, so you probably don't want to use this on extremely long
messages.
Returns truth on success, false on error.
sign PARAMHASH
Instance method, override. Append a signature to the message. The
params are:
Attach
Instead of appending the text, add it to the message as an
attachment. The disposition will be "inline", and the description
will indicate that it is a signature. The default behavior is to
append the signature to the text of the message (or the text of its
first part if multipart). MIME-specific; new in this subclass.
File
Use the contents of this file as the signature. Fatal error if it
can't be read. As per superclass method.
Force
Sign it even if the content-type isn't "text/*". Useful for non-
standard types like "x-foobar", but be careful! MIME-specific; new
in this subclass.
Remove
Normally, we attempt to strip out any existing signature. If true,
this gives us the NLINES parameter of the remove_sig call. If zero
but defined, tells us not to remove any existing signature. If
undefined, removal is done with the default of 10 lines. New in
this subclass.
Signature
Use this text as the signature. You can supply it as either a
scalar, or as a ref to an array of newline-terminated scalars. As
per superclass method.
For MIME messages, this method is reasonably cautious: it will only
attempt to sign a message with a content-type of "text/*", unless
"Force" is specified.
If you send this message to a multipart entity, it will relay it to the
first part (the others usually being the "attachments").
Warning: currently slurps the whole message-part into core as an array
of lines, so you probably don't want to use this on extremely long
messages.
Returns true on success, false otherwise.
suggest_encoding
Instance method. Based on the effective content type, return a good
suggested encoding.
"text" and "message" types have their bodies scanned line-by-line for
8-bit characters and long lines; lack of either means that the message
is 7bit-ok. Other types are chosen independent of their body:
Major type: 7bit ok? Suggested encoding:
-----------------------------------------------------------
text yes 7bit
text no quoted-printable
message yes 7bit
message no binary
multipart * binary (in case some parts are bad)
image, etc... * base64
sync_headers OPTIONS
Instance method. This method does a variety of activities which ensure
that the MIME headers of an entity "tree" are in-synch with the body
parts they describe. It can be as expensive an operation as printing
if it involves pre-encoding the body parts; however, the aim is to
produce fairly clean MIME. You will usually only need to invoke this
if processing and re-sending MIME from an outside source.
The OPTIONS is a hash, which describes what is to be done.
Length
One of the "official unofficial" MIME fields is "Content-Length".
Normally, one doesn't care a whit about this field; however, if you
are preparing output destined for HTTP, you may. The value of this
option dictates what will be done:
COMPUTE means to set a "Content-Length" field for every non-
multipart part in the entity, and to blank that field out for every
multipart part in the entity.
ERASE means that "Content-Length" fields will all be blanked out.
This is fast, painless, and safe.
Any false value (the default) means to take no action.
Nonstandard
Any header field beginning with "Content-" is, according to the
RFC, a MIME field. However, some are non-standard, and may cause
problems with certain MIME readers which interpret them in
different ways.
ERASE means that all such fields will be blanked out. This is done
before the Length option (q.v.) is examined and acted upon.
Any false value (the default) means to take no action.
Returns a true value if everything went okay, a false value otherwise.
tidy_body
Instance method, override. Currently unimplemented for MIME messages.
Does nothing, returns false.
Output
dump_skeleton [FILEHANDLE]
Instance method. Dump the skeleton of the entity to the given
FILEHANDLE, or to the currently-selected one if none given.
Each entity is output with an appropriate indentation level, the
following selection of attributes:
Content-type: multipart/mixed
Effective-type: multipart/mixed
Body-file: NONE
Subject: Hey there!
Num-parts: 2
This is really just useful for debugging purposes; I make no guarantees
about the consistency of the output format over time.
print [OUTSTREAM]
Instance method, override. Print the entity to the given OUTSTREAM, or
to the currently-selected filehandle if none given. OUTSTREAM can be a
filehandle, or any object that reponds to a print() message.
The entity is output as a valid MIME stream! This means that the
header is always output first, and the body data (if any) will be
encoded if the header says that it should be. For example, your output
may look like this:
Subject: Greetings
Content-transfer-encoding: base64
SGkgdGhlcmUhCkJ5ZSB0aGVyZSEK
If this entity has MIME type "multipart/*", the preamble, parts, and
epilogue are all output with appropriate boundaries separating each.
Any bodyhandle is ignored:
Content-type: multipart/mixed; boundary="*----*"
Content-transfer-encoding: 7bit
[Preamble]
--*----*
[Entity: Part 0]
--*----*
[Entity: Part 1]
--*----*--
[Epilogue]
If this entity has a single-part MIME type with no attached parts, then
we're looking at a normal singlepart entity: the body is output
according to the encoding specified by the header. If no body exists, a
warning is output and the body is treated as empty:
Content-type: image/gif
Content-transfer-encoding: base64
[Encoded body]
If this entity has a single-part MIME type but it also has parts, then
we're probably looking at a "re-parsed" singlepart, usually one of type
"message/*" (you can get entities like this if you set the
"parse_nested_messages(NEST)" option on the parser to true). In this
case, the parts are output with single blank lines separating each, and
any bodyhandle is ignored:
Content-type: message/rfc822
Content-transfer-encoding: 7bit
[Entity: Part 0]
[Entity: Part 1]
In all cases, when outputting a "part" of the entity, this method is
invoked recursively.
Note: the output is very likely not going to be identical to any input
you parsed to get this entity. If you're building some sort of email
handler, it's up to you to save this information.
print_body [OUTSTREAM]
Instance method, override. Print the body of the entity to the given
OUTSTREAM, or to the currently-selected filehandle if none given.
OUTSTREAM can be a filehandle, or any object that reponds to a print()
message.
The body is output for inclusion in a valid MIME stream; this means
that the body data will be encoded if the header says that it should
be.
Note: by "body", we mean "the stuff following the header". A printed
multipart body includes the printed representations of its subparts.
Note: The body is stored in an un-encoded form; however, the idea is
that the transfer encoding is used to determine how it should be
output. This means that the "print()" method is always guaranteed to
get you a sendmail-ready stream whose body is consistent with its head.
If you want the raw body data to be output, you can either read it from
the bodyhandle yourself, or use:
$ent->bodyhandle->print($outstream);
which uses read() calls to extract the information, and thus will work
with both text and binary bodies.
Warning: Please supply an OUTSTREAM. This override method differs from
Mail::Internet's behavior, which outputs to the STDOUT if no filehandle
is given: this may lead to confusion.
print_header [OUTSTREAM]
Instance method, inherited. Output the header to the given OUTSTREAM.
You really should supply the OUTSTREAM.
stringify
Instance method. Return the entity as a string, exactly as "print"
would print it. The body will be encoded as necessary, and will contain
any subparts. You can also use "as_string()".
stringify_body
Instance method. Return the encoded message body as a string, exactly
as "print_body" would print it. You can also use "body_as_string()".
If you want the unencoded body, and you are dealing with a singlepart
message (like a "text/plain"), use "bodyhandle()" instead:
if ($ent->bodyhandle) {
$unencoded_data = $ent->bodyhandle->as_string;
}
else {
### this message has no body data (but it might have parts!)
}
stringify_header
Instance method. Return the header as a string, exactly as
"print_header" would print it. You can also use "header_as_string()".
NOTES
Under the hood
A MIME::Entity is composed of the following elements:
· A head, which is a reference to a MIME::Head object containing the
header information.
· A bodyhandle, which is a reference to a MIME::Body object containing
the decoded body data. This is only defined if the message is a
"singlepart" type:
application/*
audio/*
image/*
text/*
video/*
· An array of parts, where each part is a MIME::Entity object. The number
of parts will only be nonzero if the content-type is not one of the
"singlepart" types:
message/* (should have exactly one part)
multipart/* (should have one or more parts)
The "two-body problem"
MIME::Entity and Mail::Internet see message bodies differently, and this
can cause confusion and some inconvenience. Sadly, I can't change the
behavior of MIME::Entity without breaking lots of code already out there.
But let's open up the floor for a few questions...
What is the difference between a "message" and an "entity"?
A message is the actual data being sent or received; usually this means
a stream of newline-terminated lines. An entity is the representation
of a message as an object.
This means that you get a "message" when you print an "entity" to a
filehandle, and you get an "entity" when you parse a message from a
filehandle.
What is a message body?
Mail::Internet: The portion of the printed message after the header.
MIME::Entity: The portion of the printed message after the header.
How is a message body stored in an entity?
Mail::Internet: As an array of lines.
MIME::Entity: It depends on the content-type of the message. For
"container" types ("multipart/*", "message/*"), we store the contained
entities as an array of "parts", accessed via the "parts()" method,
where each part is a complete MIME::Entity. For "singlepart" types
("text/*", "image/*", etc.), the unencoded body data is referenced via
a MIME::Body object, accessed via the "bodyhandle()" method:
bodyhandle() parts()
Content-type: returns: returns:
------------------------------------------------------------
application/* MIME::Body empty
audio/* MIME::Body empty
image/* MIME::Body empty
message/* undef MIME::Entity list (usually 1)
multipart/* undef MIME::Entity list (usually >0)
text/* MIME::Body empty
video/* MIME::Body empty
x-*/* MIME::Body empty
As a special case, "message/*" is currently ambiguous: depending on the
parser, a "message/*" might be treated as a singlepart, with a
MIME::Body and no parts. Use bodyhandle() as the final arbiter.
What does the body() method return?
Mail::Internet: As an array of lines, ready for sending.
MIME::Entity: As an array of lines, ready for sending.
If an entity has a body, does it have a soul as well?
The soul does not exist in a corporeal sense, the way the body does; it
is not a solid [Perl] object. Rather, it is a virtual object which is
only visible when you print() an entity to a file... in other words,
the "soul" it is all that is left after the body is DESTROY'ed.
What's the best way to get at the body data?
Mail::Internet: Use the body() method.
MIME::Entity: Depends on what you want... the encoded data (as it is
transported), or the unencoded data? Keep reading...
How do I get the "encoded" body data?
Mail::Internet: Use the body() method.
MIME::Entity: Use the body() method. You can also use:
$entity->print_body()
$entity->stringify_body() ### a.k.a. $entity->body_as_string()
How do I get the "unencoded" body data?
Mail::Internet: Use the body() method.
MIME::Entity: Use the bodyhandle() method! If bodyhandle() method
returns true, then that value is a MIME::Body which can be used to
access the data via its open() method. If bodyhandle() method returns
an undefined value, then the entity is probably a "container" that has
no real body data of its own (e.g., a "multipart" message): in this
case, you should access the components via the parts() method. Like
this:
if ($bh = $entity->bodyhandle) {
$io = $bh->open;
...access unencoded data via $io->getline or $io->read...
$io->close;
}
else {
foreach my $part (@parts) {
...do something with the part...
}
}
You can also use:
if ($bh = $entity->bodyhandle) {
$unencoded_data = $bh->as_string;
}
else {
...do stuff with the parts...
}
What does the body() method return?
Mail::Internet: The transport-encoded message body, as an array of
lines.
MIME::Entity: The transport-encoded message body, as an array of lines.
What does print_body() print?
Mail::Internet: Exactly what body() would return to you.
MIME::Entity: Exactly what body() would return to you.
print out just "the stuff after the header"?
Say I have an entity which might be either singlepart or multipart. How do I
Mail::Internet: Use print_body().
MIME::Entity: Use print_body().
Why is MIME::Entity so different from Mail::Internet?
Because MIME streams are expected to have non-textual data...
possibly, quite a lot of it, such as a tar file.
Because MIME messages can consist of multiple parts, which are most-
easily manipulated as MIME::Entity objects themselves.
Because in the simpler world of Mail::Internet, the data of a message
and its printed representation are identical... and in the MIME world,
they're not.
Because parsing multipart bodies on-the-fly, or formatting multipart
bodies for output, is a non-trivial task.
This is confusing. Can the two classes be made more compatible?
Not easily; their implementations are necessarily quite different.
Mail::Internet is a simple, efficient way of dealing with a "black box"
mail message... one whose internal data you don't care much about.
MIME::Entity, in contrast, cares very much about the message contents:
that's its job!
Design issues
Some things just can't be ignored
In multipart messages, the "preamble" is the portion that precedes the
first encapsulation boundary, and the "epilogue" is the portion that
follows the last encapsulation boundary.
According to RFC-1521:
There appears to be room for additional information prior
to the first encapsulation boundary and following the final
boundary. These areas should generally be left blank, and
implementations must ignore anything that appears before the
first boundary or after the last one.
NOTE: These "preamble" and "epilogue" areas are generally
not used because of the lack of proper typing of these parts
and the lack of clear semantics for handling these areas at
gateways, particularly X.400 gateways. However, rather than
leaving the preamble area blank, many MIME implementations
have found this to be a convenient place to insert an
explanatory note for recipients who read the message with
pre-MIME software, since such notes will be ignored by
MIME-compliant software.
In the world of standards-and-practices, that's the standard. Now for
the practice:
Some "MIME" mailers may incorrectly put a "part" in the preamble.
Since we have to parse over the stuff anyway, in the future I may allow
the parser option of creating special MIME::Entity objects for the
preamble and epilogue, with bogus MIME::Head objects.
For now, though, we're MIME-compliant, so I probably won't change how
we work.
AUTHOR
Eryq (eryq@zeegee.com), ZeeGee Software Inc (http://www.zeegee.com). David
F. Skoll (dfs@roaringpenguin.com) http://www.roaringpenguin.com
All rights reserved. This program is free software; you can redistribute
it and/or modify it under the same terms as Perl itself.
VERSION
$Revision: 1.10 $ $Date: 2005/01/13 19:23:15 $
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