[zeeboo]

A simple map was discussed in the post. The problem it has is that it has unbounded growth. The sync.Pool approach is a best effort to avoid allocations only. If its API was changed to return sentinel pointers rather than the string, it wouldn't have the guarantee that Intern(x) == Intern(x) when x == x.

[benhoyt]

Thanks. I re-read this paragraph from the original article and it makes more sense now:

> use a zone mapping table, mapping between zone index integers and zone name strings. That’s what the Go standard library does internally. But then we’re left susceptible to an attack where an adversary forces us to parse a bunch of IP addresses with scopes and we forever a bloat a mapping table that we don’t have a good opportunity to ever shrink. The Go standard library doesn’t need to deal with this, as it only ever maps interfaces that exist on the machine and doesn’t expose the integers to users in representations; its net.IPAddr.Zone field is a string.

[bradfitz]

Whoops, I just fixed that typo too. (not yet deployed)