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-- Echo server program
module Main (main) where
import Control.Concurrent (forkFinally)
import qualified Control.Exception as E
import Control.Monad (unless, forever, void)
import qualified Data.ByteString as S
import Network.Socket
import Network.Socket.ByteString (recv, sendAll)
main :: IO ()
main = runTCPServer Nothing "3000" talk
where
talk s = do
msg <- recv s 1024
unless (S.null msg) $ do
sendAll s msg
talk s
-- from the "network-run" package.
runTCPServer :: Maybe HostName -> ServiceName -> (Socket -> IO a) -> IO a
runTCPServer mhost port server = withSocketsDo $ do
addr <- resolve
E.bracket (open addr) close loop
where
resolve = do
let hints = defaultHints {
addrFlags = [AI_PASSIVE]
, addrSocketType = Stream
}
head <$> getAddrInfo (Just hints) mhost (Just port)
open addr = do
sock <- socket (addrFamily addr) (addrSocketType addr) (addrProtocol addr)
setSocketOption sock ReuseAddr 1
withFdSocket sock $ setCloseOnExecIfNeeded
bind sock $ addrAddress addr
listen sock 1024
return sock
loop sock = forever $ do
(conn, _peer) <- accept sock
void $ forkFinally (server conn) (const $ gracefulClose conn 5000)
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