Re: net.inet6.ip6.deembed_scopeid removal

[re-sending email with as non-html]

Hey,

I would like to deprecate net.inet6.ip6.deembed_scopeid sysctl while leaving the current default behaviour.

This sysctl controls whether IPv6 scope is embedded in the IPv6 address or not when reading or writing route/interface/ifaddr data via rtsock/sysctl.

Embedding scope in the address is a hack, that overwrites some of the bits that can be used otherwise. It was probably implemented that way to simplify route table interactions, as rtable uses this hack to add link-local addresses to the same radix tree.

The change to fix the userland api by filling in sin6_scopeid and avoid touching IPv6 address was added in r243187, 7 years ago. It provided the sysctl in question, allowing to preserve compatibility with older applications, by reverting to the old behavior.

7 years looks like enough timeframe for the applications to be adjusted. Unless any major objections arise, I'm going to remove the code and make de-embedded IPv6 addresses the only option on July 5 2020.

/Alexander