3 ms·

Well, John Carmack is a game programmer, at least originally. In games one has strong upper limits on how long it can take to calculate the next frame. So, it m

by cjfd 4y ago

Well, John Carmack is a game programmer, at least originally. In games one has strong upper limits on how long it can take to calculate the next frame. So, it may very well be that something can be said for this in this context. I am not sure in general, though. If one limits the length of the name of a person in some record one can start waiting until one day a person arrives that has a name that is one character longer and then a programmer needs to get involved to increase the limit. Okay, maybe there exists a ridiculously large maximum name length such that this problem is unlikely to occur. Then one may still have the problem that if all people would have names that approach this limit, the system still might get too slow as well. So maybe we should impose a limit on the sum of all the lengths of all the names in the system. Hmmm... Kind of gets a bit too complicated and arbitrary for my tastes. I think for many systems Carmarcks advice really is not very good.

layer8 4y ago
There should be limits. What if someone pastes the text of the bible into the name field? What if you want to send an email containing the name, and you hit the maximum email size accepted by the SMTP server (they all have a limit)? What if you want to send a postal letter and print the name on the envelope? Not setting explicit limits either means that you still have implicit limits, but you don’t know what they are and where and when you’ll run into them, or it means you’re opening yourself up to DoS attacks, because your database or your backups or your AWS bill will run amok.
- GauntletWizard 4y ago
  I have legitimately used the complete works of William Shakespeare, unabridged, as a password. Even that is in megabytes, and not significant load for bcrypt2. Not that there should be no limits at all, but the upper bound should be relatively high.
  - asynchronous 4y ago
    Doesn’t bcrypt2 essentially truncate every source input to no longer than 35 characters?
    - layer8 4y ago
      It’s 72 bytes, but yes. Probably a good reason to have a length limit on the password field if you use bcrypt.
  - mellavora 4y ago
    Now all I have to do is guess which order you used them in, and I'll have full access to your system!
- jagged-chisel 4y ago
  Yes, you need input validation that enforces some kind of limit. But every layer of processing (function calls, RPC…) in the stack from the text entry through the network through the database engine to the disk doesn’t need to be concerned with the 200 character limit for a name. The database can give you an error if the size is exceeded. The input field can warn the user about the limit. But the code that converts from the user’s chosen encoding to utf-8 doesn’t need to know anything about those limits.
  - layer8 4y ago
    Yes, the important thing is to have a data schema that defines the limits and that is enforced at all system boundaries. That way you also identify the cases where the limits may not match those of the protocols you are talking to (mappings between schemata, basically).

by cjfd 4y ago

layer8 4y ago

There should be limits. What if someone pastes the text of the bible into the name field? What if you want to send an email containing the name, and you hit the maximum email size accepted by the SMTP server (they all have a limit)? What if you want to send a postal letter and print the name on the envelope? Not setting explicit limits either means that you still have implicit limits, but you don’t know what they are and where and when you’ll run into them, or it means you’re opening yourself up to DoS attacks, because your database or your backups or your AWS bill will run amok.

GauntletWizard 4y ago
I have legitimately used the complete works of William Shakespeare, unabridged, as a password. Even that is in megabytes, and not significant load for bcrypt2. Not that there should be no limits at all, but the upper bound should be relatively high.
- asynchronous 4y ago
  Doesn’t bcrypt2 essentially truncate every source input to no longer than 35 characters?
  - layer8 4y ago
    It’s 72 bytes, but yes. Probably a good reason to have a length limit on the password field if you use bcrypt.
- mellavora 4y ago
  Now all I have to do is guess which order you used them in, and I'll have full access to your system!
jagged-chisel 4y ago
Yes, you need input validation that enforces some kind of limit. But every layer of processing (function calls, RPC…) in the stack from the text entry through the network through the database engine to the disk doesn’t need to be concerned with the 200 character limit for a name. The database can give you an error if the size is exceeded. The input field can warn the user about the limit. But the code that converts from the user’s chosen encoding to utf-8 doesn’t need to know anything about those limits.
- layer8 4y ago
  Yes, the important thing is to have a data schema that defines the limits and that is enforced at all system boundaries. That way you also identify the cases where the limits may not match those of the protocols you are talking to (mappings between schemata, basically).