3 ms·

Hadn't seen that law before. Absolutely hate it. The harm from poor input invalidation over time is massive.

by alex_sf 4y ago

endgame 4y ago
I imagine that it made more sense when your update cycle involved the postal system and took months.
deleted 4y ago
[deleted]
ajosh 4y ago
You have to think about Postel's law in terms of protocols and mistakes in your implementation. You assume your implementation isn't perfect and neither is the other. Do your best to be perfect and if you get something that isn't quite right, do your best to handle it well. That doesn't mean you don't validate inputs, it means that if data should come with a \n but instead comes with \n\r, you should treat it as a \n.
- tfigment 4y ago
  I think you miss their point which is that has led to a large number of security bugs. Because it is then path to exploits and sloppiness which then cannot be corrected because of backward compatibility or such.
  - shadowgovt 4y ago
    Postel's Law isn't why we can't correct errors for backwards compatibility reasons. We can't correct those because backwards compatibility is necessary to creating a global network that lasts decades. It's the railway effect... One simply can't expect every player to update their architecture religiously because they can't afford to, therefore what is made public tends to stick around for ages, and anything that fails to recognize that stickiness (IPv6 is my go to example) does so at its own peril.
  - mcguire 4y ago
    Anyone else remember the time, years ago, when someone introduced a new performance feature to TCP, using an otherwise-unused bit in the header. Unfortunately, rolling it out turned into a giant clusterfuck because many routers on the internet interpreted "this bit is unused" as "this bit will always be zero"?
    - salawat 4y ago
      Ah yes, the fyranny of the middlebox.
bartwe 4y ago
Hyrum's Law is the near reverse of Postel's and i think it should be taught.
Oxidation 4y ago
Indeed, it's what got us "quirks mode" and that took years and years to dig the internet out from under.

Hadn't seen that law before. Absolutely hate it. The harm from poor input invalidation over time is massive.

endgame 4y ago

I imagine that it made more sense when your update cycle involved the postal system and took months.

deleted 4y ago

[deleted]

ajosh 4y ago

You have to think about Postel's law in terms of protocols and mistakes in your implementation. You assume your implementation isn't perfect and neither is the other. Do your best to be perfect and if you get something that isn't quite right, do your best to handle it well. That doesn't mean you don't validate inputs, it means that if data should come with a \n but instead comes with \n\r, you should treat it as a \n.

tfigment 4y ago
I think you miss their point which is that has led to a large number of security bugs. Because it is then path to exploits and sloppiness which then cannot be corrected because of backward compatibility or such.
- shadowgovt 4y ago
  Postel's Law isn't why we can't correct errors for backwards compatibility reasons. We can't correct those because backwards compatibility is necessary to creating a global network that lasts decades. It's the railway effect... One simply can't expect every player to update their architecture religiously because they can't afford to, therefore what is made public tends to stick around for ages, and anything that fails to recognize that stickiness (IPv6 is my go to example) does so at its own peril.
- mcguire 4y ago
  Anyone else remember the time, years ago, when someone introduced a new performance feature to TCP, using an otherwise-unused bit in the header. Unfortunately, rolling it out turned into a giant clusterfuck because many routers on the internet interpreted "this bit is unused" as "this bit will always be zero"?
  - salawat 4y ago
    Ah yes, the fyranny of the middlebox.

bartwe 4y ago

Hyrum's Law is the near reverse of Postel's and i think it should be taught.

Oxidation 4y ago

Indeed, it's what got us "quirks mode" and that took years and years to dig the internet out from under.