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 RFCs 2045, 2046, 2047, 2048 and 2049.
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-2046, 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 2045. 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. Returns an array reference.
Each array entry is a newline-terminated line.
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.
- 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.
- Say I have an entity which might be either singlepart or
multipart. How do I print out just "the stuff after the
header"?
- 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 2046:
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.
SEE ALSO¶
MIME::Tools, MIME::Head, MIME::Body, MIME::Decoder, Mail::Internet
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.