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\r\n \r\n \r\nPHP: PEAR mimeDecode Module
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While most MIME email is totally useless, it would be better if it was \r\n sent as a plain text message, MIME sometimes is useful. When sending \r\n attachments, for example. In this article, we will see how we can decode \r\n MIME messages with PHP.
\r\nWe will use the mimeDecode module to do the actual decoding for us. \r\n mimeDecode is part of the PEAR library. \r\n PEAR is already installed if you have a newer version of PHP, but if you \r\n don\'t it\'s also easy to install.
\r\nHow to get PEAR and mimeDecode
\r\nBefore trying to install PEAR and the mimeDecode module, you should \r\n first make sure that you don\'t yet have it. If you have a recent version \r\n of PHP (> 4.3.0pre1), the PEAR base installation is already installed \r\n on your system. Since the mimeDecode module is part of the PEAR core, \r\n that\'s also installed. To check whether you have to install the mimeDecode \r\n or not, you can run the following PHP script:
<?php\r\ninclude(\'Mail/mimeDecode.php\');\r\n?>\r\n\r\n
If this doesn\'t give an error, you the mimeDecode module is installed \r\n on your system. If it does, you\'ll have to install PEAR (or upgrade your \r\n version of PHP). Read the PEAR manual for \r\n instructions.
\r\nMIME: an introduction
\r\nBefore you can successfully write a script that decodes MIME email, \r\n you\'ll have to know a little about the anatomy of a MIME message. I\'ll \r\n give you a short introduction to MIME. If you want to read more about the \r\n details of MIME, there is a chapter \r\n available from O\'Reilly.
\r\nA tradition email
\r\nThe source of a basic, non-MIME email looks like this:
From: Gijs van Tulder <gvtulder@example.com>\r\nTo: thelist@lists.evolt.org\r\nSubject: Decoding MIME mail\r\nDate: Wed, 12 Mar 2003 10:26:59 +0100\r\n\r\nHi, this is my message.\r\n\r\n
The first lines of this email contain headers, data about this message. \r\n These headers consist of a header name, before the colon, and some data, \r\n after the colon. (If you are familiar with the HTTP headers, you\'ll notice \r\n that email headers use the same syntax.) There are actually many more \r\n possible headers that I didn\'t include in this example, but all headers \r\n are in the form Name: Data. You can see the headers of your \r\n email in your email program. (In Microsoft Outlook 2000, for example, \r\n right-click on the message and select \'Options\'.)
The body of the message, in our example Hi, this is my \r\n message. starts after the blank line that follows the headers.
A MIME email
\r\nWe\'ll now see what happens with our message when we add a MIME \r\n attachment to it.
From: Gijs van Tulder <gvtulder@example.com>\r\nTo: thelist@lists.evolt.org\r\nSubject: Decoding MIME mail\r\nDate: Wed, 12 Mar 2003 10:26:59 +0100\r\nMIME-Version: 1.0\r\nContent-Type: multipart/mixed; boundary=\"MyBoundary\"\r\n\r\nThis is a multi-part message in MIME format.\r\n\r\n--MyBoundary\r\nContent-Type: text/plain; charset=\"iso-8859-1\"\r\nContent-Transfer-Encoding: 7bit\r\n\r\nHi, this is my message. See the attached image!\r\n\r\n--MyBoundary\r\nContent-Type: image/gif; name=\"myimage.gif\"\r\nContent-Transfer-Encoding: base64\r\nContent-Disposition: attachment; filename=\"myimage.gif\"\r\n\r\nR0lGODlhogBrAPcAAAAAAP///zwKC2UhIrdPUKU0OMmLjagEDJIEDZEmLduztW8HD64YJlUJEXkX\r\n...omitted many lines like the above...\r\ngahQUgx4n5kQWQQJ0sqEREAAADs=\r\n\r\n--MyBoundary--\r\n\r\n
As you can see, our message now contains two different parts: the \r\n message body, Hi...image!, and an encoded form of the image, \r\n R01GO...AADs=. We\'ll take a closer look at these parts in a \r\n moment. How does your mail program know where the different parts begin \r\n and end? Look at the headers, and you\'ll see the answer: there is a new \r\n header called Content-Type, with a boundary variable. In this \r\n example, I\'ve set the boundary to MyBoundary. The MIME parts \r\n are separated by a line with two dashes and that boundary string: \r\n --MyBoundary. At the end of the message, the boundary is \r\n followed by two dashes to indicate the end.
Note that this boundary can be set to any possible string. It\'s fairly \r\n obvious that normal mail programs don\'t use \'MyBoundary\' as the boundary \r\n string, but take a longer random string. It still has the same effect, \r\n though.
\r\nThe MIME parts
\r\nNow, let\'s take a look at the MIME parts. You\'ll notice that these \r\n parts look a lot like the email message: it starts with a number of \r\n headers, followed by an empty line and then there is the body.
Content-Type: image/gif; name=\"myimage.gif\"\r\nContent-Transfer-Encoding: base64\r\nContent-Disposition: attachment; filename=\"myimage.gif\"\r\n\r\nR0lGODlhogBrAPcAAAAAAP///zwKC2UhIrdPUKU0OMmLjagEDJIEDZEmLduztW8HD64YJlUJEXkX\r\n...omitted many lines like the above...\r\ngahQUgx4n5kQWQQJ0sqEREAAADs=\r\n\r\n
This is the MIME part containing the attached image. You see the \r\n Content-Type header, that tells us more about the type of \r\n this part. In our example, this part is a gif image. The original filename \r\n is also included in the headers.
The body of this part looks very strange. Many similar lines followed \r\n the first line of characters, but I deleted them except from the last \r\n line. What you see here is an encoded version of the original file. Since \r\n an email message can only contain normal text, the binary form of the \r\n image had to be translated to a text form. This is called MIME encoding. \r\n The Content-Transfer-Encoding tells us what type of encoding \r\n was used. The PEAR mimeDecode module, and every other MIME compatible \r\n email reader, will use this information to decode the file.
Decoding the message
\r\nNow that we know a little about MIME email, we can almost start writing \r\n the script. But wait, you\'ll first have to get a message that your script \r\n can parse. If you\'re using Linux/Unix, you can send yourself a MIME email \r\n and copy your mbox file to get the source of that message. You can also \r\n set up a email \r\n to PHP script to get the message source. If you just want to test the \r\n mimeDecode module, you can also just download the source of my example \r\n message. In this example script, I will assume that the source email \r\n is saved as $input.
Initialising mimeDecode
\r\nTo load the mimeDecode module, we just have to include \r\n mail/mimeDecode. The PEAR path is specified in PHP\'s \r\n include_path, so we don\'t have to worry about the absolute location of \r\n this file.
include(\'mail/mimeDecode\');\r\n\r\n
Setting the parameters
\r\nThe mimeDecode module accepts five parameters. \r\n include_bodies determines whether we want the bodies of the \r\n MIME parts to be returned. If decode_bodies is set to true, \r\n the encoded MIME parts (files etc.) are decoded. If \r\n decode_headers is true, mimeDecode decodes the message \r\n headers. Since we want the whole message to be decoded, we\'ll set these \r\n three boolean parameters to true.
The fourth parameter, crlf, tells mimeDecode the line \r\n ending type. The default is \\r\\n (carrier return, line feed), which works \r\n in most cases. We won\'t specify this. The last parameter is called \r\n input and is used to send the input message to mimeDecode. \r\n
$params[\'include_bodies\'] = true;\r\n$params[\'decode_bodies\'] = true;\r\n$params[\'decode_headers\'] = true;\r\n$params[\'input\'] = $input;\r\n\r\n
Running decode()
\r\nIt\'s time to run mimeDecode\'s decode() function, the \r\n function that decodes the MIME message and returns a nice structure. The \r\n easiest way to run decode() is without creating a new object. \r\n That does mean that we have to tell PHP in which class \r\n decode() is to be found.
$structure = Mail_mimeDecode::decode($params);\r\n\r\n
The decoded message is saved in $structure.
The mimeDecode output
\r\nWe\'ve now got the decoded message in the $structure \r\n variable. If you run print_r($structure);, you\'ll get a nice \r\n view of the anatomy of that structure.
- \r\n
$structure->headers: An array \r\n containing the headers of the message. \r\n$structure->headers[\'subject\']contains the \r\nSubject:header and so on. Note that multiple headers with \r\n the same name are saved in an array, like: \r\n$structure->headers[\'received\'][0]. \r\n$structure->ctype_primary: The \r\n first part of the message\'s content type. If the content type is \r\nmultipart/mixed, this is set tomultipart. \r\n$structure->ctype_secondary: The \r\n second part of the message\'s content type. (multipart/mixed\r\n gives a value ofmixed. \r\n$structure->ctype_parameter: An \r\n array of the parameters of the content type. In case of a MIME message \r\n this includes theboundary=value. \r\n$structure->content_disposition: \r\n Contains the value of theContent-Disposition:header, if \r\n set. In case of an attachment, this is set toattachment. \r\n$structure->d_parameters: As with \r\n theContent-Type:header, any parameters of the \r\nContent-Disposition:header are returned in this array. \r\n Attachments, for instance, bring afilenameparameter. \r\n$structure->body: The body of the \r\n message or the MIME part. In general, the main message of a MIME email \r\n doesn\'t have a body value. \r\n$structure->parts: This is an array \r\n of all MIME parts found in the message. Each of these parts has the same \r\n properties as the$structurevariable described here. Eg. \r\n the headers of$structures->parts[0]can be found in \r\n$structures->parts[0]->headersetc.
Saving all attached files
\r\nWe can now walk through the $structure->parts array and \r\n save each attachment we find.
foreach ($structure->parts as $part) {\r\n // only save if an attachment\r\n if (isset($part->disposition) and\r\n ($part->disposition==\'attachment\') {\r\n // open file\r\n $fp = fopen($part->ctype_parameters[\'filename\'], \'w\');\r\n // write body\r\n fwrite($fp, $part->body);\r\n // close file\r\n fclose($fp);\r\n }\r\n}\r\n\r\n For each part, we check if it has a Content-Disposition: \r\n header set to \'attachment\'. We open a file with the name given by the \r\n filename parameter of the Content-Type: header. \r\n We then save the (decoded) body of this part in that file.
Listing all images
\r\nIn the same way, we can list all images and their sizes by checking the \r\n ctype_primary and body values. We can then send \r\n this list to the sender of the original email.
$list = \'\';\r\nforeach ($structure->parts as $part) {\r\n // is this an image?\r\n if ($part->ctype_primary==\'image\') {\r\n $list .= $part->ctype_parameters[\'filename\'].\': \'.\r\n strlen($part->body).\" bytes\\n\";\r\n }\r\n}\r\n// send this list\r\n$to = $structure->headers[\'from\'];\r\n$subject = \'Re: \'.$structure->headers[\'subject\'];\r\n$body = \"You sent us these images:\\n\\n$list\\n\\nThank you very much!\";\r\n$headers = \'From: \'.$structure->headers[\'to\'];\r\nmail($to, $subject, $body, $headers);\r\n\r\n If the ctype_primary is \'image\' (from image/gif, \r\n image/jpeg etc.), we add the filename and the length of the \r\n body string to the list. After we viewed all images, we send \r\n the list to the sender of the original email. We use the information of \r\n the original email, the From:, Subject: and \r\n To: headers, to make a nice reply.
What\'s next?
\r\nBy now, you should be able to write your own scripts using the \r\n mimeDecode module. You could, for example, write a script that lets you \r\n just email images and get them published on your web log. In the rare \r\n event that you are a teacher, you could save all documents that your \r\n students send you in your \'incoming files\' directory, without having to \r\n open each message first.
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Gijs is a full time Dutch student in economics and a spare time Web \r\n developer. He spends his time developing scripts using PHP, MySQL and \r\n other external programs.
\r\nVisit his site at: http://gvtulder.f2o.org/
\r\n\r\n
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