From: Steve Tuckner <stevetuckner@...>
Date: 2004-02-14T05:29:24+09:00
Subject: Windows UDP oddities/failures

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I am having a peculiar problem with UDP in windows. A simple test that 
runs under linux fails in windows.  Below are two scripts one for a 
server and one for a client. The server starts by waiting for a packet 
and then when it gets on it sends a response. The client starts by 
sending a packet and waiting for a response.
 
On Linux the server prints the frame received and and waits for the next 
one. The client prints the frame it received back from the server and exits.
 
On Windows, if the bind call is included, then the first packet never 
gets sent by the client. If the bind call is ommitted, then the recvfrom 
fails with
 
client.rb:12:in `recvfrom': The network is busy.- recvfrom(2) (Errno::E054)
 
If the bind call is added back in after the connect call, then bind 
fails with:
 
client.rb:11:in `bind': Invalid argument - bind(2) (Errno::EINVAL)
 
Any ideas on this one?
 
The select on the client does succeed so that it knows there is 
something to receive. It just can't get its hands on it ;-(
 
Steve Tuckner
 
ruby 1.8.0 (2003-08-04) [i386-mswin32]
Windows XP
 
-- Client.rb -------------------------
#!/usr/bin/env ruby
 
require "socket"

socket = UDPSocket.open
server.bind(nil, 1601)
socket.connect("192.168.4.80", 1600) # FIXME get port from send page 
response
socket.send("hello", 0)
if select([socket], nil, nil, 3) then
  p socket.recvfrom(64)
end
 
-- Server.rb -------------------------
#!/usr/bin/env ruby
 
require "socket"
 
address = ARGV.shift or raise "ip address needed"
server = UDPSocket.open
server.bind(nil, 1600)
server.connect(address, 1601)
while true
 p server.recvfrom(1200)
 server.send("hello", 0)
end
 
Steve Tuckner

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