In the socket library, MRI 1.9 defines Addrinfo < Data. We don't have it.
Resolv::DNS fails in 1.9 mode
Missing method Socket::ip_address_list
Socket.new seems broken -- throws exceptions on valid params
It's a large .c file in MRI, but a lot of that appears to be platform-specific struct-wrangling. Might be simple enough to wrap JDK address APIs.
FWIW, "Data" appears to be nothing more than a non-allocatable Object subclass. Several utility classes and structs extend it.
I'm committing a partial impl, and filed JRUBY-6394 for some missing Socket features we'll need to run MRI's test (test/externals/ruby1.9/socket/test_addrinfo.rb).
Started it at least:
Author: Charles Oliver Nutter <email@example.com>
Date: Mon Jan 30 07:33:16 2012 -0600
First stab at implementing Addrinfo for JRUBY-6393.
Fixed enough with recent commits (around master@7db1d63) that filled out Addrinfo.