I thought this was to combat cross-site request forgery attacks?
Else couldn't one set up malicious scripts to up-or downvote many stories, or post comments under someone else's name?
"Unknown or expired link." - Why?
21–30 of 142 posts
Re: "Unknown or expired link." - Why?
#22Yes please, fix it already. I this problem where in another site we would be posting complains from random blog posts over and over again.
Re: "Unknown or expired link." - Why?
#23I've been wondering about this for a long time, but just as a data point if anyone cares, it has reached the point recently that HN is basically unusable for me a lot of the time, and I really am starting to give up on trying and spend more time elsewhere instead. Perhaps one visitor is no great loss -- I'm hardly the personality around here that someone like patio11 is -- but I hope my contribution is constructive,…
When writing comments, always make a copy of your text before hitting submit (CTRL+A, CTRL+C). A good strategy for any text form on the web.
"go back one page" (alt-left arrow) recovers your text on HN
Re: "Unknown or expired link." - Why?
#24The HN server uses a table of closures to implement those links (the id code for the closure is the bit after fnid= in the url). When the HN server starts running out of memory, it drops entries from this table. When your browser asks for an entry that is no longer in this table, you get the "Unknown or expired link" error. This is a crazy design, but unless someone would like to patch the source code and get PG to a…
It's not crazy at all, it greatly simplifies development to use callbacks for actions rather than manually encoding the necessary state into the URL. Techniques such as this are what enable a single developer to be so productive by automating boring and time consuming stuff.
Except it doesn't appear to work robustly, which makes it poor design. "Automating boring and time consuming stuff," is all well and good if it actually produces a functional system, but that concern is secondary to robustness.
Re: "Unknown or expired link." - Why?
#25I'm getting this error when using the login link right now!
EDIT: The only way I was able to login was to use the 'add comment' button on this post.
Re: "Unknown or expired link." - Why?
#26It's an artefact of the way in which news.arc (actually srv.arc) uses functions for links. Here's the key code: (= dead-msg* "\nUnknown or expired link.") (defop-raw x (str req) (w/stdout str (aif (fns* (sym (arg req "fnid"))) (it req) (pr dead-msg*)))) If the fnid (function ID) isn't in the fns* list then you get the dead message. (def flink (f) (string fnurl* "?fnid=" (fnid (fn (req) (prn) (f req))))) In many place…
I would be interested to know how much state is in those closures. If it is less than 200 or so bytes, it would not be impractical to encode it (b64) in the url for the next page (rather than a reference to the state).
You don't want to execute code from URLs. (Yes, you can use cryptography to "sign" URLs you create. Don't try that at home unless you know the difference between MACs and hashes, and how to avoid timing attacks.)
Re: "Unknown or expired link." - Why?
#27Earlier quoted context omitted.
When writing comments, always make a copy of your text before hitting submit (CTRL+A, CTRL+C). A good strategy for any text form on the web.
"go back one page" (alt-left arrow) recovers your text on HN
This is browser dependent (although many modern browsers do keep form content in the history).
Re: "Unknown or expired link." - Why?
#28I've been wondering about this for a long time, but just as a data point if anyone cares, it has reached the point recently that HN is basically unusable for me a lot of the time, and I really am starting to give up on trying and spend more time elsewhere instead. Perhaps one visitor is no great loss -- I'm hardly the personality around here that someone like patio11 is -- but I hope my contribution is constructive,…
When writing comments, always make a copy of your text before hitting submit (CTRL+A, CTRL+C). A good strategy for any text form on the web.
Indeed, that became a habit for me a while ago after certain social discussion sites and on-line tools I use frequently went all Web 2.0 and broke the back button when a form submission failed, typically because the form fields were only added dynamically using JS so when you go back they simple aren't there any more according to your browser. Mercifully, HN has yet to introduce that particular "improvement".
That's not really the point, though, is it? The important thing is whether posters who want to offer a useful comment and/or mitigate a poor comment can do so. Once HN gets into unknown/expired mode at the moment, it seems common that even basic things like "More" links and logging in can fail as soon as you load/refresh a page, at which point the site is effectively unusable: you can't contribute even if you have something worthwhile to add saved away in your clipboard from the previous failed attempt.
Re: "Unknown or expired link." - Why?
#29Earlier quoted context omitted.
I would be interested to know how much state is in those closures. If it is less than 200 or so bytes, it would not be impractical to encode it (b64) in the url for the next page (rather than a reference to the state).
You don't want to execute code from URLs. (Yes, you can use cryptography to "sign" URLs you create. Don't try that at home unless you know the difference between MACs and hashes, and how to avoid timing attacks.)
Whoa, whoa. Putting the state from the closure in the url is not the same as putting the closure in the url.
Re: "Unknown or expired link." - Why?
#30This happens to me a lot while reading HN. I hit "More" and by the time I am done reading a few comments on a handful of entries, the next "More" has expired, and so has the current. This only happens on HN (at least to me).
Actually _right_now_ I cannot click "more"(on the first page) without hitting the "Unknown or expired link" page ... so I cannot go past the first page :/ -- Someone should submit a patch :)