yatac42 · HackerTrans

3 maanden geledendiscuss

From a quick look it seems like it's "as fast as a linter" because it is a linter. The homepage says "Not just generic AST patterns", but I couldn't find any rule that did anything besides AST matching. I don't see anything in the code that would enable any kind of control or data flow analysis.

yatac42

5 maanden geledendiscuss

> My takeaway is that his test email bounced

What test email? I see no mention of a test email in the blog post. The mail that bounced was the one with the verification link from Viva.

yatac42

2 jaar geledendiscuss

> but we shouldn't forget that this kind of failure can only happen starting from an ambiguous grammar specification

I don't think that's true. The following CFG is unambiguous:

  S ::= A S | A
  A ::= 'a' | 'a' 'b'

Yet if we translate this 1-to-1 to a PEG (without changing the order of the alternatives), it's not going to match any input with 'b's in it, so it doesn't match the same language.

yatac42

2 jaar geledendiscuss

Note that they're actually citing "Mitchell, Webb et al." in the paper.

yatac42

3 jaar geledendiscuss

> A lot of these games with fancy anti cheat protection the cheat tools basically just tell the server "spawn me a vehicle right here" and the server just does it.

Citation needed. I'd be quite surprised if it were common for servers of professional games to trust the client in that sense (i.e. allowing it to decide game logic like what gets spawned where).

As far as I'm aware the most common types of multiplayer cheats are

* wall hacks, which you could probably prevent by not sending the client any information about objects that the player can't see, but that would require the server to calculate the line of sight for every player/object, * and aim bots, which I don't think you could prevent at all on the server side since they don't rely on the bot having access to any information that the player isn't supposed to have. They just rely on the bot being better at aiming. I suppose if you did all rendering server side and only sent the rendered graphics to the client (i.e. streaming), that would make it harder for the bot because it'd now have to do image recognition to find the target, but that just makes it harder, not impossible. Plus, game streaming wasn't well received for a reason and anyway, I don't think that's what you had in mind when you talked about "not trusting the client".

yatac42

3 jaar geledendiscuss

And perhaps more relevantly, the regex from the article also works fine in RE2.

yatac42

3 jaar geledendiscuss

> re2 uses a DFA-based system instead that just doesn't support the kinds of regexes that catastrophically backtrack

There are certain fearures that are harder or impossible to implement with RE2's approach, but it's not true that it doesn't support the kind of regex that would catastrophically backtrack using a backtracking engine.

`(.*a)*b` would be a (silly) example of a regex that can catastrophically backtrack using backtracking engines and re2 supports it just fine without backtracking.

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