What's up with all those equals signs anyway?
(lars.ingebrigtsen.no)610 points by todsacerdoti 16 hours ago
610 points by todsacerdoti 16 hours ago
I discovered X-Face[0] through gmane! Such a blast from the past.
I'd forgotten that! Yeah, I believe Lars also wrote a huge chunk of the current Gnus. I stopped using it a while back and maybe someone else came along and rewrote it again, replacing all his code, but I don't think that's the case.
Gnus was absolutely delightful back in the day. I moved on around the time I had to start writing non-plaintext emails for work reasons. It's also handy to be using the same general email apps and systems as 99.99% of the rest of the world. I still have a soft spot in my heart for it.
PS: Also, I have no idea whatsoever why someone would downvote you for that. Weird.
The real punchline is that this is a perfect example of "just enough knowledge to be dangerous." Whoever processed these emails knew enough to know emails aren't plain text, but not enough to know that quoted-printable decoding isn't something you hand-roll with find-and-replace. It's the same class of bug as manually parsing HTML with regex, it works right up until it doesn't, and then you get congressional evidence full of mystery equals signs.
> It's the same class of bug as manually parsing HTML with regex, it works right up until it doesn't
I'm sure you already know this one, but for anyone else reading this I can share my favourite StackOverflow answer of all time: https://stackoverflow.com/a/1732454
I prefer the question about CPU pipelines that gets explained using a railroad switch as example. That one does a decent job of answering the question instead of going of on a, how to best put it, mentally deranged one page rant about regexes with the lazy throw away line at the end being the only thing that makes it qualify as an answer at all.
The regex answer is from the very old days of Stackoverflow, before fun was banned. I agree it barely qualifies as answer, but considering that the question has over 4 million page views (which almost puts it in the top 100 most viewed questions all-time), it has reached a lot people. The answer probably had much more influence than any serious answer on that topic. So I'd say the author did a good job.
For anyone wondering about the railroad switch post: https://stackoverflow.com/questions/11227809/why-is-processi...
This is new to me, and a wonderful dive that I wish I was aware of during my OS course. Thanks!
It took me years to notice, but did you catch that the answer actually subtly misinterprets what the question is asking for?
Guy (in my reading) appears to talk about matching an entire HTML document with regex. Indeed, that is not possible due to the grammars involved. But that is not what was being asked.
What was being asked is whether the individual HTML tags can be parsed via regex. And to my understanding those are very much workable, and there's no grammar capability mismatch either.
The thing is, even when parsing html "correctly" (whatever that is) regexes will still be used. Sure, There will be a bunch of additional structures and mechanisms involved, but you will be identifying tokens via a bunch of regexes.
So yes, while it is an inspired comidic genius of a rant, and sort of informative in that it opens your eyes to the limitations of regexes, it sort of brushes under the rug all the places that those poor maligned regular expressions will be used when parsing html.
I know this is grumpy but this I’ve never liked this answer. It is a perfect encapsulation of the elitism in the SO community—if you’re new, your questions are closed and your answers are edited and downvoted. Meanwhile this is tolerated only because it’s posted by a member with high rep and username recognition.
I think this answer was tolerated when SO wasn't as bad as it is now, and wouldn't be tolerated now from anyone.
As someone who used to write custom crawlers 20 years ago, I can confirm that regular expressions worked great. All my crawlers were custom designed for a page and the sites were mostly generated by some CMS and had consistent HTML. I don't remember having to do much bug fixes that were related to regular expression issues.
I don't suggest writing generic HTML parsers that works with any site, but for custom crawlers they work great.
Not to say that the tools available are the same now as 20 years ago. Today I would probably use puppeteer or some similar tool and query the DOM instead.
Funny how differently people can perceive things. That's my least favorite SO answer of all time, and I cringe every time I see it.
It's a very bad answer. First of all, processing HTML with regex can be perfectly acceptable depending on what you're trying to do. Yes, this doesn't include full-blown "parsing" of arbitrary HTML, but there are plenty of ways in which you might want to process or transform HTML that either don't require producing a parse tree, don't require perfect accuracy, or are operating on HTML whose structure is constrained and known in advance. Second, it doesn't even attempt to explain to OP why parsing arbitrary HTML with regex is impossible or poorly-advised.
The OP didn't want his post to be taken over by someone hamming it up with an attempt at creative writing. He wanted a useful answer. Yes, this answer is "quirky" and "whimsical" and "fun" but I read those as euphemisms for "trying to conscript unwilling victims into your personal sense of nerd-humor".
There's nothing that brings joy into this world quite like the guy waiting around to tell people he doesn't like the thing they like.
The whole argument hinges on one word in your post: arbitrary.
I parse my own HTML I produce directly in a context where I fully control the output. It works fine, but parsing other people’s HTML is a lesson in humility. I’ve also done that, but I did it as a one time thing. I parsed a specific point in time, refusing to change that at any point.
> We see that that’s a quite a long line. Mail servers don’t like that
Why do mail server care about how long a line is? Why don't they just let the client reading the mail worry about wrapping the lines?
SMTP is a line–based protocol, including the part that transfers the message body
The server needs to parse the message headers, so it can't be an opaque blob. If the client uses IMAP, the server needs to fully parse the message. The only alternative is POP3, where the client downloads all messages as blobs and you can only read your email from one location, which made sense in the year 2000 but not now when everyone has several devices.
But everything after headers can (almost) be a blob. Just copy buffers while taking care to track CRLF and look if what follows is a space. In fact, you have to do it anyhow, because line-folding is allowed in headers as well! And this "chunking long lines" technique has been around since the 70s, when people started writing parsers on top of hand-crafted buffered I/O.
Hey, POP3 still makes sense. Having a local copy of your emails is useful.
If you want it to be the only copy and not sync with anything
POP3 is line–based too, anyway. Maybe you can rsync your maildir?
Mails are (or used to be) processed line-by-line, typically using fixed-length buffers. This avoids dynamic memory allocation and having to write a streaming parser. RFC 821 finally limited the line length to at most 1000 bytes.
Given a mechanism for soft line breaks, breaking already at below 80 characters would increase compatibility with older mail software and be more convenient when listing the raw email in a terminal.
This is also why MIME Base64 typically inserts line breaks after 76 characters.
In early days, many/most people also read their email on terminals (or printers) with 80-column lines, so breaking lines at 72-ish was considered good email etiquette (to allow for later quoting prefix ">" without exceeding 80 characters).
I don't think kids today realize how little memory we had when SMTP was designed.
For example, the PDP-11 (early 1970s), which was shared among dozens of concurrent users, had 512 kilobytes of RAM. The VAX-11 (late 1970s) might have as much as 2 megabytes.
Programmers were literally counting bytes to write programs.
I assure you we were not, at least it wasn’t really necessary. Virtual Memory is a powerful drug.
This is how email work(ed) over smtp. When each command was sent it would get a '200'-class message (success) or 400/500-class message (failure). Sound familiar?
telnet smtp.mailserver.com 25
HELO
MAIL FROM: me@foo.com
RCPT TO: you@bar.com
DATA
blah blah blah
how's it going?
talk to you later!
.
QUIT
For anyone who wants to try this against a modern server:
openssl s_client -connect smtp.mailserver.com:smtps -crlf
220 smtp.mailserver.com ESMTP Postfix (Debian/GNU)
EHLO example.com
250-smtp.mailserver.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-AUTH PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250-DSN
250-SMTPUTF8
250 CHUNKING
MAIL FROM:me@example.com
250 2.1.0 Ok
RCPT TO:postmaster
250 2.1.5 Ok
DATA
354 End data with <CR><LF>.<CR><LF>
Hi
.
250 2.0.0 Ok: queued as BADA579CCB
QUIT
221 2.0.0 ByeThis brings back some fun memories from the 1990s when this was exactly how we would send prank emails.
Yep! And also, if you included a blank line and then the headers for a new email in the bottom of your message, you could tell the server, hey, here comes another email for you to process!
If you were typing into a feedback form powered by something from Matt’s Script Archive, there was about a 95% chance you could trivially get it to send out multiple emails to other parties for every one email sent to the site’s owner.
RCPT TO specifies the destination (recipient) address, the "sender" is what is written in MAIL FROM.
However what most mail programs show as sender and recipient is neither, they rather show the headers contained in the message.
"BITNET was a co-operative university computer network in the United States founded in 1981 by Ira Fuchs at the City University of New York (CUNY) and Greydon Freeman at Yale University."
https://en.wikipedia.org/wiki/BITNET
BITNET connected mainframes, had gateways to the Unix world and was still active in the 90s. And limited line lengths … some may remember SYSIN DD DATA … oh my goodness …
https://www.ibm.com/docs/en/zos/2.1.0?topic=execution-systsi...
Back in 80s-90s it was common to use static buffers to simplify implementation - you allocate a fixed size buffer and reject a message if it has a line longer than the buffer size. SMTP RFC specifies 1000 symbols limit (including \r\n) but it's common to wrap around 87 symbols so it is easy to examine source (on a small screen).
The simplest reason: Mail servers have long had features which will send the mail client a substring of the text content without transferring the entire thing. Like the GMail inbox view, before you open any one message.
I suspect this is relevant because Quoted Printable was only a useful encoding for MIME types like text and HTML (the human readable email body), not binary (eg. Attachments, images, videos). Mail servers (if they want) can effectively treat the binary types as an opaque blob, while the text types can be read for more efficient transfer of message listings to the client.
As far as I can remember, most mail servers were fairly sane about that sort of thing, even back in the 90’s when this stuff was introduced. However, there were always these more or less motivated fears about some server somewhere running on some ancient IBM hardware using EBCDIC encoding and truncating everything to 72 characters because its model of the world was based on punched cards. So standards were written to handle all those bizarre systems. And I am sure that there is someone on HN who actually used one of those servers...
EBCDIC wasn't the problem, this was (part of) the problem:
https://www.ibm.com/docs/en/zos/2.1.0?topic=execution-systsi...
And BITNET …
RFC822 explicitly says it is for readability on systems with simple display software. Given that the protocol is from 1982 and systems back then had between 4 and 16kb RAM in total it might have made sense to give the lower end thin client systems of the day something preprocessed.
Also it is an easy way to stop a denial of service attack. If you let an infinite amount in that field. I can remotely overflow your system memory. The mail system can just error out and hang up on the person trying the attack instead of crashing out.
Surely you don't need the message to be broken up into lines just for that. Just read until a threshold is reached and then close the connection.
Keep in mind that in ye olden days, email was not a worldwide communication method. It was more typical for it to be an internal-only mail system, running on whatever legacy mainframe your org had, and working within whatever constraints that forced. So in the 90s when the internet began to expand, and email to external organizations became a bigger thing, you were just as concerned with compatibility with all those legacy terminal-based mail programs, which led to different choices when engineering the systems.
Are you certain? Not OP, but a huge chunk of early RFCs was about how to let giant IBM systems talk to everyone else, specifying everything from character sets (nearly universally “7-bit ASCII”) to end of line/message characters. Otherwise, IBM would’ve tried to make EBCDIC the default for everything.
For instance, consider FTP’s text mode, which was primarily a way to accidentally corrupt your download when you forgot to type “bin” first, but was also handy for getting human readable files from one incompatible system to another.
I thought the article would be about the various meanings of operators like = == === .=. <== ==> <<== ==>> (==) => =~=
Email is one of those cursed standards where the committee wasn't building a protocol from scratch, but rather trying to build a universal standard by gluing together all of the independently developed existing systems in some way that might allow them to interoperate. Verifying that a string a user has typed is a valid email address is close to impossible short of just throwing up your hands and allowing anything with a @ somewhere in it.
Email is one of the very few success cases of the xkcd Standards meme: https://xkcd.com/927/ - and it's due to practicality and ingenuity on the part of people who made very creative parsers and placed real-world understanding behind every word of the early RFCs.
Without a unified email standard, the world would look incredibly different today, especially as it bootstrapped open communication between different countries and institutions in developing every protocol since.
The most interesting thing to me wasn't the equals signs, which I knew are from quoted-printable, but the fact that when an equals sign appears, a letter that should have been preceding or following it is missing. It's as if an off-by-one error has occurred, where instead of getting rid of the equals sign, it's gotten rid of part of the actual text. Perhaps the CRLF/LF thing is part of it.
I'm just wondering why this problem shows up now. Why do lots of people suddenly post their old emails with a defective QP decoder?
> For some reason or other, people have been posting a lot of excerpts from old emails on Twitter over the last few days.
On the risk of having missed the latest meme or social media drama, but does anyone know what this "some reason or other" is?
Edit: Question answered.
you presume cor=rect
Of course the Epstein files are serious.
But not everybody has every single global development / news event IVed into their veins. Many of us just don’t keep updated on global news such that we may not be aware of an event that happened in the last 3 days.
Important news tends to get to me eventually. And there is usually nothing I can do about something personally anyway (at least within a short time horizon), so there is really very little value in trying to stay informed of the absolute latest developments. The signal to noise ratio is far too low, and it also induces a bunch of unnecessary anxiety and stress.
So yes, believe it or not very many people are unaware of this.
> So what’s happened here? Well, whoever collected these emails first converted from CRLF (i.e., “Windows” line ending coding) to “NL” (i.e., “Unix” line ending coding). This is pretty normal if you want to deal with email. But you then have one byte fewer:
I think there is a second possible conclusion, which is that the transformation happened historically. Everyone assumes these emails are an exact dump from Gmail, but isn't it possible that Epstein was syncing emails from Gmail to a third party mail server?
Since the Stackoverflow post details the exact situation in 2011, I think we should be open to the idea that we're seeing data collected from a secondary mail server, not Gmail directly.
Do we have anything to discount this?
(If I'm not mistaken, I think you can also see the "=" issue simply by applying the Quoted-Printable encoding twice, not just by mishandling the line-endings, which also makes me think two mail servers. It also explains why the "=" symbol is retained.)
In one of the email PDFs I saw an XML plist with some metadata that looked like it was from Apple's Mail.app, so these might be extracted from whatever internal format that uses.
What happened here is what always happens with all printed and digital material that goes through some evidentiary process.
The shot-callers demand the material, which is a task fobbed off onto some nobody intern who doesn't matter (deliberately, because the lawyers and career LEOs don't want any "officer of the court" or other "party" to put eyes on things they might need to deny knowing about later.) They use only the most primitive, mechanical method possible, with little to no discretion. The collected mass of mangled junk is then shipped to whoever, either in boxes or on CD-ROM/DVD (yes, still) or something. Then, the reverse process is done, equally badly, again by low-level staff, also with zero discretion and little to no technical knowledge or ability, for exactly the same reasons, to get the material into some form suitable for filing or whatever.
Through all of this, the subtle details of data formats and encodings are utterly lost, and the legal archive fills with mangled garbage like raw quoted-printable emails. The parties involved have other priorities, such as minimizing the number of people involved in the process, and tight control over the number of copies created. Their instinct is not to bring in a bunch of clever folk that might make the work product come out better, because "better" for them is different than "better" for Twitter or Facebook. Also, these disclosures are inevitably and invariably challenged by time: the obligation to provide one thing or another is fought to the last possible minute, and when the word does finally go out there is next to no time to piddle around with details.
In the Epstein case, the disclosures were done years ago, the original source material (computers, accounts, file systems, etc.) have all long since been (deliberately) destroyed, and what the feds have is the shrapnel we see today.
Fun how the archive.today article near the top has this exact issue
https://web.archive.org/web/20260203094902/https://lars.inge...
Did the site get the HN kiss of death?
(The title of the blog reminded me the late Bob Pease [1] who had the signature, "What's all this XXX stuff, anyhow?" [2] where XXX might be "noise gain", "capacitor leakage"…)
Same here. I did notice what I think was an actual error on someone's part, there was a chart in the files comparing black to white IQ distributions, and well, just look at it:
https://nitter.net/AFpost/status/2017415163763429779?s=201
Something clearly went wrong in the process.
Me too. I first assumced it was an OCR error, then remembered they were emails and wouldn't need to go through OCR. Then I thought that the US Government is exactly the kind of place to print out millions of emails only to scan them back in again.
I'm glad to know the real reason!
CLRF vs LF strikes again. Partly at least.
I wonder why even have a max line length limit in the first place? I.e. is this for a technical reason or just display related?
Remember that back in the mists of time, computers used typewriter-esque machines for user interaction and text output. You had to send a CR followed by an LF to go to the next line on the physical device. Storing both characters in the file meant the OS didn't need to insert any additional characters when printing. Having two separate characters let you do tricks like overstriking (just send CR, no LF)
I haven't seen them other than in the submission - but if the length matches up it may be that they were processed from raw email, the RFC defines a length to wrap at.
Edit: yes I think that's most likely what it is (and it's SHOULD 78ch; MUST 998ch) - I was forgetting that it also specifies the CRLF usage, it's not (necessarily) related to Windows at all here as described in TFA.
Here it is in my 'notmuch-more' email lib: https://github.com/OJFord/amail/blob/8904c91de6dfb5cba2b279f...
> it's not (necessarily) related to Windows at all here as described in TFA.
The article doesn't claim that it's Windows related. The article is very clear in explaining that the spec requires =CRLF (3 characters), then mentions (in passing) that CRLF is the typical line ending on Windows, then speculates that someone replaced the two characters CRLF with a one character new line, as on Unix or other OSs.
“Insert characters”?
Consider converting the original text (maintaining the author’s original line wrapping and indentation) to base64. Has anything been “inserted” into the text? I would suggest not. It has been encoded.
Now consider an encoding that leaves most of the text readable, translates some things based on a line length limit, and some other things based on transport limitations (e.g. passing through 7-bit systems.) As long as one follows the correct decoding rules, the original will remain intact - nothing “inserted.” The problem is someone just knowledgeable enough to be aware that email is human readable but not aware of the proper decoding has attempted to “clean up” the email for sharing.
SMTP is a line-oriented protocol. The server processes one line at a time, and needs to understand headers.
Infinite line length = infinite buffer. Even worse, QP is 7-bit (because SMTP started out ASCII only), so characters >127 get encoded as three bytes (equal, then two hex digits), so a 500-character non-ASCII UTF8 line is 1500 bytes.
It all made sense at the time. Not so much these days when 7-bit pipes only exist because they always have.
No, because there is a clear separation between the content and the envelop. You wouldnt expect the post office to open your physical letters and write routing instructions to the postmen for delivery
But I agree with sibling comment: it makes more sense when its called "encoding" instead of "inserting chars into original stream"
> You wouldnt expect the post office to open your physical letters and write routing instructions to the postmen for delivery
Digital communication is based on the postmen reading, transcribing and copying your letters. There is a reason why digital communication is treated differently then letters by the law and why the legally mandated secrecy for letters doesn't apply to emails.
It's called escaping, and almost every protocol has it. HN must convert the & symbol to & for displaying in HTML. Many wire protocols like SATA or Ethernet must insert a 1 after a certain number of consecutive 0s to maintain electrical balance. Don't remember which ones — don't quote me that it's SATA and Ethernet.
My main takeaway from this article, is that I want to know what happened to the modified pigs with non-cloven hoofs
Great. Can't wait for equal signs to be the next (((whatever this is))). Maybe it's a secret code. j/k
On a side note: There are actually products marketed as kosher bacon (it's usually beef or turkey). And secular Jews frequently make jokes like this about our kosher bros who aren't allowed to eat the real stuff for some dumb reason like it has too many toes.
But... pigs _do_ have cloven hooves! The issue is that they're not ruminant.
That said, there is a _possibly_ kosher pig: https://en.wikipedia.org/wiki/Babirusa#Relationship_with_hum...
"It’s a fascinating case of 'Abstraction Leak'.
We’ve become so accustomed to modern libraries handling encoding transparently that when raw data surfaces (like in these dumps), we often lack the 'Digital Archeology' skills to recognize basic Quoted-Printable.
These artifacts (=20, =3D) are effectively fossils of the transport layer. It’s a stark reminder that underneath our modern AI/React/JSON world, the internet is still largely held together by 7-bit ASCII constraints and protocols from the 1980s.
Unicode labels U+000A as all of "LINE FEED (LF)", "new line (NL)" and "end of line (EOL)". I'm guessing different names were imported from slightly different character sets, although I understand the all-uppercase name to be the main/official one.
https://en.wikipedia.org/wiki/Metal_umlaut
The writer presumably knows that umlauts and other non-ascii characters are functional in many languages. "rock döts" is poking fun at the trend in a certain tranche of anglophone rock/metal to use them in a purely aesthetic way in band names etc.
No, the article is quite explicit that that isn't what happened.
Rock dots? You mean diacritics? Yeah someone invented them: the ancient Greeks, idiöt.
It's not the character, its the way / context in which it's used
I know what he was referring to. But the use case is obviously languages other than English, not the Motörhead fan club newsletter.
For context, this is the Lars Ingebrigtsen who wrote the manual for Gnus[0], a common Emacs package for reading email and Usenet. It’s clever, funny, and wildly informative. Lars has probably forgotten more about email parsing than 99% of us here will ever have learned.
The manual itself says[1]:
> Often when I read the manual, I think that we should take a collection up to have Lars psycho-analysed.
0: https://www.gnu.org/software/emacs/manual/html_mono/gnus.htm...
1: https://www.gnus.org/manual.html