Re: We do not need pg_promote_v4_to_v6_addr/mask

I wrote:
> We have some code in the server that attempts to match IPv4 address
> entries in pg_hba.conf to incoming connections that are in IPv6 protocol
> but have addresses in the range ::ffff:xxxx:xxxx (the IPv4-in-IPv6
> subrange). As revealed by today's bug report from Hugo Osvaldo Barrera,
> this code has been broken since commit f3aec2c7f51904e7 (shipped in 9.0),
> as a result of sloppiness with a memcpy() source address. How is it that
> nobody noticed?

BTW, a bit of digging in the git logs and mail archives says that the code
in question was originally added in 7.4 (commit 3c9bb8886df7d56a), in
response to this discussion:
http://www.postgresql.org/message-id/flat/200309012156(dot)05874(dot)t(dot)maekitalo(at)epgmbh(dot)de

So back in 2003 there were Linux boxes that actively transformed IPv4
connection addresses to ::ffff:xxxx:xxxx format. Current Linux behavior
is the exact opposite: even if you try to say ::ffff:xxxx:xxxx in a
connection request, IPv4 is what comes out the other end. I find the same
on current OS X btw. So I'm definitely now of the opinion that this is a
workaround for a long-deceased Linux kernel bug, and not something we need
to continue^X^X^Xresume supporting.

regards, tom lane