From: Roger Pack <rogerpack2005@...>
Date: 2007-12-21T16:48:39+09:00
Subject: Re: Socket.gethostbyname and Reverse Lookups: A Strange and Terrible Saga

> Note, I'm not altogether surprised it worked for you on OS X,
> because it also used to work on all my previous linux OS's I still
> have available for testing... But something has apparently changed
> recently.

The thing that got me was ipv6 versus ipv4.
My code was

class Socket
  class << self
    def getIP hostName
      ipInt = gethostbyname(hostName)[3]
      return "%d.%d.%d.%d" % [ipInt[0], ipInt[1], ipInt[2], ipInt[3]]
    end

    def getHostIP
      return getIP(Socket.gethostname())
    end
    alias gethostip getHostIP
  end
end

run Socket.getHostIP and it works fine on Linux.
Run it on OSX, and then the lookup returns and ipv6 addy (at least on
my machine), and no ipv4's, so the string creation above returned half
an ipv6 addy--not too useful.

Appears that
 Socket.getaddrinfo(Socket.gethostname, 0, Socket::AF_UNSPEC,
Socket::SOCK_STREAM, nil, Socket::AI_CANONNAME)

Yields a more reliable, 'understandable' output.
My vote would be for the 'not cross-ip version friendly' gethostbyname
to be replaced by this or something along those lines, but that's just
me.
Take care.
-Roger