From: GOTO Kentaro <gotoken@...>
Date: 2002-09-21T10:09:10+09:00
Subject: Re: Error in Sys::Host on FreeBSD

At Fri, 20 Sep 2002 22:14:39 +0900,
Berger, Daniel <djberge@qwest.com> wrote:
> That's interesting.  It *should* work without the each method.  I just
> tested it on Solaris using an August build of 1.7.2 and it worked ok.

The error was raised on FreeBSD release and current.  

I scanned host.c and found the function host_free() looks needless
unless I misunderstand.  And ip_addr() doesn't return any value when 
it is called as an iterator. 


By the way, two comments about host.c...

You wrote 
   Host.ip_addr.each do |ip| # multi-nic system
but one has to use something platform dependent, e.g., ifconfig (or
ipconfig on ms-windows) to know *all* addresses of a machine, afaik.
getbyhostname() or getaddrinfo() do only reverse lookup for a name of
host but *not all* interfaces are associated often to the name given
by hostname().

I think that use of Socket is not overkill to get michine's addresses
because Socket has getaddrinfo() which resolves protocol-independently. 
It seems pretty hard to provide getaddrinfo() or an equivalent
function for various platforms where the function is missing.  

So, a lazy person's shows another Sys::Host below :)  
This is IPv6 ready, 

  require "socket"
  module Sys
    module Host
      include Socket::Constants
      module_function

      def hostname
        Socket::gethostname()
      end

      def ip_addr(af = AF_UNSPEC, serv = nil, &block)
        addrs = Socket.getaddrinfo(Socket::gethostname(), serv, af)
        addrs.map!{|i| i[3]}
        addrs.uniq!
        return addrs unless block_given?
        addrs.each(&block)
      end
    end
  end

  if __FILE__ == $0
    puts "hostname: #{Sys::Host::hostname}"
    puts "IP addresses: #{Sys::Host::ip_addr.join(', ')}"
    Sys::Host::ip_addr{|i| puts "==> #{i}"}
  end

-- Gotoken