[Haskell-cafe] UDP

[John Van Enk]

Try something like this:
module Main where

import Network.Socket

main = withSocketsDo $ do
    -- Make a UDP socket
    s <- socket AF_INET Datagram defaultProtocol

    -- We want to listen on all interfaces (0.0.0.0)
    bindAddr <- inet_addr "0.0.0.0"

    -- Bind to 0.0.0.0:30000
    bindSocket s (SockAddrInet 30000 bindAddr)

    -- Read a message of max length 1000 from some one
    (msg,len,from) <- recvFrom s 1000

    putStrLn $ "Got the following message from " ++ (show from)
    putStrLn msg

Does this help? As Stephan said, you missed the bind step.

/jve


On Sun, Jan 25, 2009 at 11:22 AM, Andrew Coppin <andrewcoppin at btinternet.com
> wrote:

> I'm trying to write a simple program that involves UDP. I was hoping
> something like this would work:
>
> module Main where
>
> import Network.Socket
>
> main = withSocketsDo main2
>
> main2 = do
>  s <- socket AF_INET Datagram defaultProtocol
>  putStrLn "Waiting..."
>  x <- recv s 100
>  putStrLn x
>
> Unfortunately, that doesn't work at all. It immediately throws an exception
> ("unknown error"). But then, the whole module seems to be completely
> undocumented. I managed to find a tiny amount of info online about the
> underlying C API, but I still don't get how the Haskell interface is
> supposed to be used. Any hints?
>
> _______________________________________________
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> Haskell-Cafe at haskell.org
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>
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