start prototyping a UDP socket server, ideas on UDP parsing

- start implementing a socket-based UDP server (cannot reply yet)
- some brainstorming about how to parse incoming UDP packet commands

Hash2Pub/.gitignore

@@ -2,3 +2,5 @@ dist-newstyle/
 *.local
 *.swp
 *.swo
+*.o
+*.hi

Hash2Pub/demoserver.hs

@@ -0,0 +1,34 @@
+{-# LANGUAGE OverloadedStrings #-}
+module Main where
+
+import Network.Socket hiding (sendTo, recvFrom)
+import Network.Socket.ByteString
+import Control.Concurrent
+import Control.Exception
+import Control.Monad (forever)
+import System.IO (
+        IOMode (ReadWriteMode)
+        , hPutStrLn
+                 )
+import qualified Data.ByteString as BS
+
+main = do
+    sock <- socket AF_INET6 Datagram defaultProtocol
+    let hints = defaultHints { addrFamily = AF_INET6, addrSocketType = Datagram}
+    addrInfos <- getAddrInfo (Just hints) (Just "::1") (Just "7331")
+    let serverAddr = addrAddress . head $ addrInfos
+    print serverAddr
+    bind sock serverAddr
+    print sock
+    forever $ do
+        receivedStuff <- recvFrom sock 65535    -- blocks
+        forkIO $ bracket newSendSocket close' (serveReceive receivedStuff)
+        return ()
+
+serveReceive (msg, fromAddr) sendSocket = do
+    putStrLn $ "Got message " ++ show msg ++ " from " ++ show fromAddr
+    sendTo sendSocket ("Hi, thx for " `BS.append` msg) fromAddr
+    return ()
+
+newSendSocket :: IO Socket
+newSendSocket = socket AF_INET6 Datagram defaultProtocol