I'm building on the work of indexing my filesystem by indexing all of my email. I have a ton of it spread across various directories and when ever I have to search for something (such as the time I flamed an entire department at FAU on a public mailing list—ah, those were the days), it's a long drawn out ordeal to find it.
Initial stab at the problem is to just index a few email headers, like
To: (and the related
Subject:—the primary headers one would
be interested in.
I was able to squish 23 different formats into four cases:
- email address and real name aren't delimited, in which case, the only thing to parse is the email address;
- email isn't delimited, but the real name is (between parentheses, or quotes), so extract the real name from between the delimeters, and anything that isn't delimited is the email address;
- email is delimited (between angle brackets or square brackets), but the real name isn't, so extract the email address, and anything that isn't delimited is the real name;
- both the email address and real name are delimited, so it's trivial to extract both.
Then, I decided to parse the
Date: header. Now, this
is specified, quite plainly:
5. DATE AND TIME SPECIFICATION 5.1. SYNTAX date-time = [ day "," ] date time ; dd mm yy ; hh:mm:ss zzz day = "Mon" / "Tue" / "Wed" / "Thu" / "Fri" / "Sat" / "Sun" date = 1*2DIGIT month 2DIGIT ; day month year ; e.g. 20 Jun 82 month = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" time = hour zone ; ANSI and Military hour = 2DIGIT ":" 2DIGIT [":" 2DIGIT] ; 00:00:00 - 23:59:59 zone = "UT" / "GMT" ; Universal Time ; North American : UT / "EST" / "EDT" ; Eastern: - 5/ - 4 / "CST" / "CDT" ; Central: - 6/ - 5 / "MST" / "MDT" ; Mountain: - 7/ - 6 / "PST" / "PDT" ; Pacific: - 8/ - 7 / 1ALPHA ; Military: Z = UT; ; A:-1; (J not used) ; M:-12; N:+1; Y:+12 / ( ("+" / "-") 4DIGIT ) ; Local differential ; hours+min. (HHMM)
Okay, clear if you're into such things. And from the most recent specification:
date-time = [ day-of-week "," ] date FWS time [CFWS] day-of-week = ([FWS] day-name) / obs-day-of-week day-name = "Mon" / "Tue" / "Wed" / "Thu" / "Fri" / "Sat" / "Sun" date = day month year year = 4*DIGIT / obs-year month = (FWS month-name FWS) / obs-month month-name = "Jan" / "Feb" / "Mar" / "Apr" / "May" / "Jun" / "Jul" / "Aug" / "Sep" / "Oct" / "Nov" / "Dec" day = ([FWS] 1*2DIGIT) / obs-day time = time-of-day FWS zone time-of-day = hour ":" minute [ ":" second ] hour = 2DIGIT / obs-hour minute = 2DIGIT / obs-minute second = 2DIGIT / obs-second zone = (( "+" / "-" ) 4DIGIT) / obs-zone
Really, the only thing this does is mandate that the year be four digits long, moves to a numeric-only timezone format and clarifies a bit where white space appears, but otherwise, is pretty much the same as the older spec.
So, if I ignore the timezone for now (because the Standard C library has such piss-poor support for it, but that's a rant for another time), the only real issue is handling two or four digit years.
And in poking around the man pages for the various Standard C library
routines, I came across
strptime(), which is the functional
strftime()—instead of converting the time to a
human representation, it'll take a human representation and convert it to a
time value. It isn't a Standard C call, but hey, why not use it for
And it appears that the two-digit/four-digit year isn't a problem for
When a century is not otherwise specified, values in the range [69,99] shall refer to years 1969 to 1999 inclusive, and values in the range [00,68] shall refer to years 2000 to 2068 inclusive; leading zeros shall be permitted but shall not be required.
man page for
Only it blew up when it encounted
Wen, 2 Mar 2005 01:39:42
Okay, make sure I start parsing past the optional day of the week. It
then blew up on
Sat Mar 5 18:58:36 2005.
What the—? That's not even a standard format! And then there
Wed,19 十二月 2001 20:23:05 (
I added the question marks
because I can't determine the character set that was used for the
month—there's nothing in that particular email that even hints
what language it might be ).
And let's not forget
9/8/99 1:01:12 AM Pacific Daylight Time
Fri Jun 28 10:07:44 PDT 2002 or even
Wed 8-Jan-2003 08:24:20.
Oh, and we mustn't forget
Tue, 23 May 100 22:18:56
I found it amazing—one of the more strictly defined fields in an email and yet there still was an amazing amount of garbage to be found (although to be fair, these anomalies account for less than one per cent of all the emails scanned, but when you have thousands of emails, it can still add up).
(And one more interesting note—I did not see one email use the military time zone format.)
I'm having a lot of fun writing the email indexing program, despite having to code around a few broken mbox files. I've also been surprised at what I've found so far (not in the “oh, I forgot about that email!” way but more in the “What the—?” way).
At first, I assumed that no
email header would be longer than 64K, but no, turns out that isn't big enough.
Turns out I have an email with a header that is 81,162 bytes in size, and it
has enough email addresses (in the
Cc: header) to populate a
small mass-mailing list (and yes, it's spam).
I'm also tracking unique sets of headers and unique message bodies (via the SHA1 hashing function). There are 118 messages with the same body but with different headers and the amusing bit is that the emails in question wheren't spam! It's from a mailing list I used to run years ago where one of the members apparently changed his email address, and for a period of time each message that went out caused his automated system to send an update to the list.
And of course, he didn't unsubscribe his old email address.
The tracking was done to keep from indexing duplicate emails (since my testing corpus is 1,600 mbox files, some of which may be backups—I don't know which ones though, which is part of the reason I'm writing this program) so in the end I should end up with a set of unique headers.
I got down to 16 emails with duplicate headers, but unique bodies.
That scared me.
A small digression: at this point, the program pulls each email out of the mbox file, and writes the headers into one file (the original, plus a few I add during processing, like the SHA1 hash results) and the body of the email into another file (my dad likes to send me photos and videos in email, so the bodies of those messages tend to be rather large, and I'm concentrating on the headers at the moment). I currently end up with about 50M of headers and almost a gigabyte-worth of email bodies. Now, continuing on …
I pick one of the duplicate hashes, scan for it, and then check the messages:
>find header_raw/ | xargs grep FFCC3E0BCBF960EBBEA583E77E51CE0CEB59E04D ./000008069:X-SHA1-Header: FFCC3E0BCBF960EBBEA583E77E51CE0CEB59E04D ./000026823:X-SHA1-Header: FFCC3E0BCBF960EBBEA583E77E51CE0CEB59E04D >grep X-SHA1 header_raw/000008069 header_raw/000026823 header_raw/000008069:X-SHA1-Header: FFCC3E0BCBF960EBBEA583E77E51CE0CEB59E04D header_raw/000008069:X-SHA1-Body: 5C823DD92D3DCDC5AD43953D72B1D60017A134D6 header_raw/000026823:X-SHA1-Header: FFCC3E0BCBF960EBBEA583E77E51CE0CEB59E04D header_raw/000026823:X-SHA1-Body: 85584F0167666BAA506E41A3D9ED927227F0FEF0 >
(Note: I can't just
grep PATTERN * because there are simply
too many files (over 45,000) which exceeds the command line limit—that's
why I use
Okay, same headers, different body. Just what is going on here? I check the bodies:
>more body/000008069 Status: RO Accept All Major Credit Cards!!! Don't be fooled by the copycats. We are one of the original company's offering merchant credit card services for all kinds of business's. [sic]
This isn't looking good—it looks like my header parsing code is missing a header. What about the other email?
>more body/000026823 Status: RO Content-Length: 2815 Lines: 104 Accept All Major Credit Cards!!! Don't be fooled by the copycats. We are one of the original company's offering merchant credit card services for all kinds of business's. [sic]
Okay, check the mbox files to see what's messing up the header parsing. What I find actually reassures me:
From email@example.com Wed Dec 12 14:13:00 2001 Return-Path: <firstname.lastname@example.org> Received: from gig.armigeron.com ([184.108.40.206]) by conman.org (8.8.7/8.8.7) with ESMTP id OAA06543 for <email@example.com>; Wed, 12 Dec 2001 14:12:59 -0500 Received: from mercury.aibusiness.net (emi.net [220.127.116.11] (may be forged)) by gig.armigeron.com (8.11.0/8.11.0) with ESMTP id fBCJ8Aa31356 for <firstname.lastname@example.org>; Wed, 12 Dec 2001 14:08:10 -0500 Received: from domainmail.ionet.net (domainmail.ionet.net [18.104.22.168]) by mercury.aibusiness.net (8.9.3/8.9.3) with ESMTP id NAA19835 for <email@example.com>; Wed, 12 Dec 2001 13:52:26 -0500 Received: from kqyfqkpby.motor.com (r145h250.afo.net [22.214.171.124] (may be forged)) by domainmail.ionet.net (8.9.1a/8.7.3) with SMTP id MAA02841; Wed, 12 Dec 2001 12:38:11 -0600 (CST) Date: Wed, 12 Dec 2001 12:38:11 -0600 (CST) Message-Id: <200112121838.MAA02841@domainmail.ionet.net> From: "griffin" <firstname.lastname@example.org> Subject: No fee! Accept Credit Cards for the Holidays! (bbjlm) Reply-To: email@example.com MIME-Version: 1.0 X-Mailer: Mozilla 4.7 [en]C-CCK-MCD NSCPCD47 (Win98; I) Content-Type: text/plain Status: RO Accept All Major Credit Cards!!!
It wasn't my code (thank God! The parsing code is getting a bit convoluted at this point), but some clueless spammer trying to add additional headers in the body of the message (the other one was the same). So I'll assume the other 14 “duplicates” are similar in nature—spammers trying to be clever.
And now, back to coding …
Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems, each with its own display, without special hardware. It's intended for users with multiple computers on their desk since each system uses its own monitor(s).
Redirecting the mouse and keyboard is as simple as moving the mouse off the edge of your screen. Synergy also merges the clipboards of all the systems into one, allowing cut-and-paste between systems. Furthermore, it synchronizes screen savers so they all start and stop together and, if screen locking is enabled, only one screen requires a password to unlock them all. Learn more about how it works.
Synergy is a neat program if you have multiple computers at your desk (plus they need to be networked).
It's also easy to configure. All I needed to configure Synergy (which is run on each computer) was:
# # See that picture above? On the left is my laptop, # blackbox. To its right is the monitor for my main # Linux desktop computer, lucy. And to the right of # lucy is the monitor for marvin, my Mac Mini. # # This configuration maps the spatial layout of the # computers to allow Synergy to move the keyboard/mouse # about the three computers. # section: screens lucy: blackbox: marvin: end section: links lucy: left = blackbox right = marvin blackbox: right = lucy marvin: left = lucy end section: aliases lucy: lucy.roswell.conman.org blackbox: blackbox.roswell.area51 marvin: marvin.roswell.area51 Sean-Conners-Computer.local end
There's more that I could configure (even remap the keys on the keyboard) but what I have above works just fine, and man, it sure beats having to hit ScrollLock-ScrollLock-0-1 or ScrollLock-ScrollLock-0-2 to switch computers. And the cut-and-paste between systems is just icing on the cake.