From: Daniel Martin <martin@...>
Date: 2006-09-06T20:51:00+09:00
Subject: Re: Total newbie, but I think I found a bug in Socket?

Patrick Toomey <ptoomey3@mac.com> writes:

><snip>

Good analysis of where the problem is.

Tell me, does this ruby script work on your two environments?

# In one script, start this first
     require 'socket'
     include Socket::Constants
     sockaddrinfo = Socket.getaddrinfo( 'localhost', 2200, AF_INET,
                                        SOCK_STREAM )[0]
     socket = Socket.new( *sockaddrinfo[4..6] )
     sockaddr = Socket.pack_sockaddr_in( sockaddrinfo[1], sockaddrinfo[3] )
     socket.bind( sockaddr )
     socket.listen( 5 )
     client, client_sockaddr = socket.accept
     puts "The client said, '#{client.readline.chomp}'"
     client.puts "Hello from script one!"
     socket.close

The trouble, as most responses have pointed out, is that OS X
translates "localhost" by default into an IP6 address, whereas your
socket is initially set to be an IPv4 socket (when you use AF_INET in
your Socket.new call).

Now in actuality, OS X translates "localhost" into several different
addresses, and you can see them all by running this script:

     require 'socket'
     def find_const(i,p)
       Socket.constants.select{|n|n=~p}.each{ |n|
         return "Socket::#{n}" if i == Socket.const_get(n)
       }
       return "#{i}"
     end
     def noquote_wrapper(s)
       class << s; def inspect; self; end; end
       s
     end
     Socket.getaddrinfo('localhost',nil).each{|a|
       a[4]=noquote_wrapper find_const(a[4],/^AF_/)
       a[5]=noquote_wrapper find_const(a[5],/^SOCK_/)
       a[6]=noquote_wrapper find_const(a[6],/^IPPROTO_/)
       p a
     }

The improved server script I have up above works by explicitly
requesting only the SOCK_STREAM / AF_INET address, and then using the
returned values in the Socket.new call, rather than using potentially
mismatched values for the socket's address family specified in the
"new" call and the address returned from pack_sockaddr_in.  Note that
when calling pack_sockaddr_in it also passes that call the IP address
rather than the hostname.

-- 
s=%q(  Daniel Martin -- martin@snowplow.org
       puts "s=%q(#{s})",s.map{|i|i}[1]       )
       puts "s=%q(#{s})",s.map{|i|i}[1]