On Sat, Feb 24, 2024 at 07:44:44PM -0500, Jeffrey Walton wrote: > On Sat, Feb 24, 2024 at 7:37 PM Andy Smith <a...@strugglers.net> wrote: > > > > [...] > > Turning back more to protocol design, we have spent decades walking > > back Postel's Law as we find more and more ways that being liberal > > in what our software accepts is untenable in the face of a hostile > > Internet. > > ++. Postel's Law is a disaster nowadays. It was fine back in the > 1980's, but it is dangerous in the toxic environments of today. > > Here's what we teach our developers: Look for any reason you can to > reject the data. If you can't find a reason, then begrudgingly perform > the processing or transformation.
There is a difference between not doing validation (eg a field being numeric) and flexibility (eg a line length being 100 bytes which is more than the specified 80 bytes). This is what Postel is talking about. Otherwise I completely agree: validate, validate, validate - if I accept your bad data then it becomes my problem, if I reject it then you have to fix it. Unfortunately people will complain if you do this "everyone accepts the data", to which I reply "please tell me exactly what it means" - which should shut them up. -- Alain Williams Linux/GNU Consultant - Mail systems, Web sites, Networking, Programmer, IT Lecturer. +44 (0) 787 668 0256 https://www.phcomp.co.uk/ Parliament Hill Computers. Registration Information: https://www.phcomp.co.uk/Contact.html #include <std_disclaimer.h>
