The lesson for any programmers reading this is to always set an upper limit for how much data you accept from someone else. Every request should have both a timeout and a limit on the amounts of data it will consume.
While that is true, I recommend on the request anyway, because it makes it abundantly clear to the programmer that requests can fail, and failure needs to be handled somehow – even if it's by killing and restarting the process.
Though the issue with ‘too many byte’ limits is that this tends to cause outages later then time has passed and now whatever the common size was is now ‘tiny’, like if you’re dealing with images, etc.
Time limits tend to also defacto limit size, if bandwidth is somewhat constrained.
Deliberately denying service in one user flow because technology has evolved is much better than accidentally denying service to everyone because some part of the system misbehaved.
Timeouts and size limits are trivial to update as legitimate need is discovered.
Oh man, I wish I could share some outage postmortems with you.
Practically speaking, putting an arbitrary size limit
somewhere is like putting yet-another-ssl-cert-that-needs-to-be-renewed in some critical system. It will eventually cause an outage you aren’t expecting.
Will there be a plausible someone to blame? Of course. Realistically, it was also inevitable someone would forget and run right into it.
Time limits tend to not have this issue, for various reasons.
> Practically speaking, putting an arbitrary size limit somewhere is like putting yet-another-ssl-cert-that-needs-to-be-renewed in some critical system. It will eventually cause an outage you aren’t expecting.
No, not at all. A TLS cert that expires takes the whole thing down for everyone. A size limit takes one operation down for one user.
But not putting the limits, leaves the door open to a different class of outages in the form of buffer overflows, that additionally can also pose a security risk as could be exploitable by an attacker.
maybe this issue would be better solved at the protocol level, but in the meantime size limit it is.
Nah, just OOM. Yes, there does need to be a limit somewhere - it just doesn’t need to be arbitrary, but based on some processing limit, and ideally will adapt as say memory footprint gets larger.
That's a lead into one of my testing strategies. It's easy to set the timeouts too short randomly, the buffer size too small. Use that to make errors happen and see what the system does. Does it hiccup and keep going or does it fall on it's face?
