About the #random thingie ... I need random data in #swad to generate unpredictable #session IDs.
I previously had an implementation trying the #Linux-originating #getrandom if available, with a fallback to a stupid internal #xorshift #PRNG, which could be disabled because it's obviously NOT cryptographically secure, and WAS disabled for the generation of session IDs.
Then I learned #arc4random is available on many systems nowadays (#FreeBSD, #NetBSD, even Linux with a recent-enough glibc), so I decided to add a compile check for it and replace the whole mess with nothing but an arc4random call IF it is available.
arc4random originates from #OpenBSD and provides the only sane way to get cryptographically secure random data. It automatically and transparently (re-)seeds from OS entropy sources, but uses an internal CSPRNG most of the time (nowadays typically #ChaCha20, so it's a misnomer, but hey ...). It never fails, it never blocks. It just works. Awesome.
