Mark's Blog

Latest — Feb 12, 2025

Simple uses of quantifiers can make regexes take quadratic time unnecessarily

Suppose I want to extract all substrings of a text that consist of one-or-more letter as followed by a letter b. This is obviously both: 1. trivial to do with a single short regex 2. trivial to do in linear time but if you try to do it with a

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CPS guidance misstates the law on defence of property?

[Disclaimer: I am a layman, NOT a qualified lawyer of any kind.] Something curious I noticed today: https://www.cps.gov.uk/legal-guidance/self-defence-and-prevention-crime currently claims that: Self defence and the prevention of crime originates from a number of different sources. Defence of the person is governed by the common

Spiked is talking nonsense about the Laurence Fox libel ruling

Spiked magazine have published an article by their chief political writer, Brendan O'Neill, about the ruling against Laurence Fox in his libel case. I've seen it shared by a bunch of Twitter users I follow and by the Free Speech Union. It's a bad article. Background The case is certainly

Don't trust the first item in the X-Forwarded-For header

Any security-related use of X-Forwarded-For (such as for rate limiting or IP-based access control) must only use IP addresses added by a trusted proxy. Using untrustworthy values can result in rate-limiter avoidance, access-control bypass, memory exhaustion, or other negative security or availability consequences. -- MDN's X-Forwarded-For article Short version: * Do

I set up a blog. It was annoying.

Today I created this blog. It's hosted in AWS and runs on the free and open source version of Ghost - although if you take a glance at the Ghost homepage, you might not even realise that there is a free and open source version, given the prominent mentions of