[MichaelGG]

Some things are just wrong. I've implemented SIP, a horrible standard. Lots of compatibility issues just from their insistence on a "human friendly" text format alone.

At any rate there's lots of things you just have to ignore, drop, reject, and otherwise muck about with in order to run a sane network. These standards are not written with software experience. They're written much in a vacuum and out of touch. This varies widely across RFCs so it might not apply to RFCs you like.

Example of a MUST for SIP and HTTP: line folding and comments in headers. Apart from being crap for performance (so much for being able to zero-copy a header value as just a pointer+len) there's zero legitimate use for these "features" of the syntax. Simply rejecting such messages is in your best interest as a network operator.