From: Nat Pryce <nat.pryce@...13media.com>
Date: 2001-08-08T09:23:16+09:00
Subject: [ruby-talk:19320] Problems with UDP on Windows

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require 'socket'

Am I being really stupid?  I cannot get UDP communication to work on =
Windows 2000.  This this program fails as soon as the server tries to =
reply to the client.

def server
    s =3D UDPSocket.new
    s.bind( nil, 4000 )
   =20
    msg,sender =3D s.recvfrom( 1024, 0 )
    domain,port,hostname,hostaddr =3D sender
   =20
    p sender
    s.send( msg.reverse, 0, hostaddr, port )
end

def client
    s =3D UDPSocket.new
    s.send( "hello", 0, 'localhost', 4000 )
    msg,sender =3D s.recvfrom( 1024, 0 )
    p msg
    p sender
end


if ARGV[0] =3D=3D "server"
    server
elsif ARGV[0] =3D=3D "client"
    client
else
    puts "usage: #{$0} {server|client}"
end

The server prints the error message:

demo_udp.rb:15:in `send': Invalid argument - "sendto(2)" (Errno::EINVAL)
        from demo_udp.rb:15:in `server'
        from demo_udp.rb:28

And the client prints the error message:

demo_udp.rb:21:in `recvfrom': Invalid argument - "recvfrom(2)" =
(Errno::EINVAL
        from demo_udp.rb:21:in `client'
        from demo_udp.rb:30

But the client has already sent a message to the server (using sendto) =
and the server has already received a message from the client (using =
recvfrom), and both recvfrom calls are identical, and the only =
difference between the sendto calls is that the server is usnig address =
data provided by the client, so it should be correct.

Any help will be greatly appreciated.


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<BODY bgColor=3D#ffffff><FONT face=3DArial size=3D2>
<DIV><BR>require 'socket'</DIV>
<DIV><BR>Am I being really stupid?&nbsp; I cannot get UDP communication =
to work=20
on Windows 2000.&nbsp; This this program fails as soon as the server =
tries to=20
reply to the client.</DIV>
<DIV>&nbsp;</DIV>
<DIV>def server<BR>&nbsp;&nbsp;&nbsp; s =3D =
UDPSocket.new<BR>&nbsp;&nbsp;&nbsp;=20
s.bind( nil, 4000 )<BR>&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp; =
msg,sender =3D=20
s.recvfrom( 1024, 0 )<BR>&nbsp;&nbsp;&nbsp; =
domain,port,hostname,hostaddr =3D=20
sender<BR>&nbsp;&nbsp;&nbsp; <BR>&nbsp;&nbsp;&nbsp; p=20
sender<BR>&nbsp;&nbsp;&nbsp; s.send( msg.reverse, 0, hostaddr, port=20
)<BR>end</DIV>
<DIV>&nbsp;</DIV>
<DIV>def client<BR>&nbsp;&nbsp;&nbsp; s =3D =
UDPSocket.new<BR>&nbsp;&nbsp;&nbsp;=20
s.send( "hello", 0, 'localhost', 4000 )<BR>&nbsp;&nbsp;&nbsp; msg,sender =
=3D=20
s.recvfrom( 1024, 0 )<BR>&nbsp;&nbsp;&nbsp; p msg<BR>&nbsp;&nbsp;&nbsp; =
p=20
sender<BR>end</DIV>
<DIV>&nbsp;</DIV>
<DIV><BR>if ARGV[0] =3D=3D "server"<BR>&nbsp;&nbsp;&nbsp; =
server<BR>elsif ARGV[0] =3D=3D=20
"client"<BR>&nbsp;&nbsp;&nbsp; client<BR>else<BR>&nbsp;&nbsp;&nbsp; puts =
"usage:=20
#{$0} {server|client}"<BR>end</DIV>
<DIV>&nbsp;</DIV>
<DIV>The server prints the error message:</DIV>
<DIV>&nbsp;</DIV>
<DIV>demo_udp.rb:15:in `send': Invalid argument - "sendto(2)"=20
(Errno::EINVAL)<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; from=20
demo_udp.rb:15:in `server'<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
from=20
demo_udp.rb:28</DIV>
<DIV>&nbsp;</DIV>
<DIV>And the client prints the error message:</DIV>
<DIV>&nbsp;</DIV>
<DIV>demo_udp.rb:21:in `recvfrom': Invalid argument - "recvfrom(2)"=20
(Errno::EINVAL<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; from=20
demo_udp.rb:21:in `client'<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; =
from=20
demo_udp.rb:30</DIV>
<DIV>&nbsp;</DIV>
<DIV>But the client has already sent a message to the server (using =
sendto) and=20
the server has already received a message from the client (using =
recvfrom), and=20
both recvfrom calls are identical, and the only difference between the =
sendto=20
calls is that the server is usnig address data provided by the client, =
so it=20
should be correct.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Any help will be greatly appreciated.</DIV>
<DIV></FONT>&nbsp;</DIV></BODY></HTML>

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