simple-server (empty) → 0.0.1

raw patch · 7 files changed

+1348/−0 lines, 7 filesdep +basedep +bytestringdep +concurrent-extrasetup-changed

Dependencies added: base, bytestring, concurrent-extra, containers, hashtables, network, time, unbounded-delays

Files

• LICENSE +674/−0
• Network/SimpleServer.hs +442/−0
• Network/SimpleServer/Examples/ChatClient.hs +69/−0
• Network/SimpleServer/Examples/ChatServer.hs +136/−0
• README.md +2/−0
• Setup.hs +5/−0
• simple-server.cabal +20/−0

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If not, see <http://www.gnu.org/licenses/>.++Also add information on how to contact you by electronic and paper mail.++  If the program does terminal interaction, make it output a short+notice like this when it starts in an interactive mode:++    <program>  Copyright (C) <year>  <name of author>+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.+    This is free software, and you are welcome to redistribute it+    under certain conditions; type `show c' for details.++The hypothetical commands `show w' and `show c' should show the appropriate+parts of the General Public License.  Of course, your program's commands+might be different; for a GUI interface, you would use an "about box".++  You should also get your employer (if you work as a programmer) or school,+if any, to sign a "copyright disclaimer" for the program, if necessary.+For more information on this, and how to apply and follow the GNU GPL, see+<http://www.gnu.org/licenses/>.++  The GNU General Public License does not permit incorporating your program+into proprietary programs.  If your program is a subroutine library, you+may consider it more useful to permit linking proprietary applications with+the library.  If this is what you want to do, use the GNU Lesser General+Public License instead of this License.  But first, please read+<http://www.gnu.org/philosophy/why-not-lgpl.html>.

@@ -0,0 +1,442 @@+{-# LANGUAGE ConstraintKinds #-} +module Network.SimpleServer(CmdHandler,+                            ConnectionHandler,+                            DisconnectHandler,+                            ClientConn(cid, lookup, modify),+                            Server(),+                            new, +                            addCommand,+                            start, +                            stop, +                            respond, +                            broadcast, +                            disconnectClient,+                            clientList) where++import Control.Concurrent hiding(modifyMVar)+import qualified Control.Concurrent.Lock as Lock+import Control.Concurrent.MVar hiding(modifyMVar)+import Control.Concurrent.Thread.Delay+import Control.Exception+import Control.Monad+import qualified Data.ByteString.Char8 as ByteS+import Data.Either+import Data.Foldable(toList)+import qualified Data.HashTable.IO as HT+import Data.IORef+import Data.Maybe+import Data.Time.Clock+import qualified Data.Sequence as Seq+import qualified Network as Net+import qualified Network.Socket as Net(close)+import System.IO(Handle, hSetBuffering, BufferMode(NoBuffering))++-- |A CmdHandler is used to handle a command in the form of a list of strings+type CmdHandler = [String] -> Server -> ClientConn -> IO ()++-- |A ConnectionHandler is called each time a client connects to the server.+type ConnectionHandler = Server -> ClientConn -> IO ()++-- |A DisconnectHandler is called each time a client is disconnected from the server.+type DisconnectHandler = Server -> ClientConn -> IO ()++{-|+Describes a Clients connection and provides an interface for+storing data associated with the client. Each client will be given+a unique cid and are Eq if their cid's are Eq.++A ClientConn comes packaged with two functions for storing additional+information in Strings. `lookup` and `modify`. The lookup function+takes a key and returns the current value of the key or the empty+string if it has never been set. The modify function+takes a key and value and updates it such that the next call to+lookup with that key will return the value provided.+-}+data ClientConn = ClientConn { -- | The Unique ID for this client+                               cid       :: Integer,+                               -- | A lookup function for this client+                               lookup    :: (String -> IO String),+                               -- | A modify function for this client+                               modify    :: (String -> String -> IO ()),+                               chandle   :: Handle,+                               host      :: Net.HostName,+                               pid       :: Net.PortNumber,+                               msgList  :: List String,+                               dead      :: MVar Bool,+                               timestamp :: TimeStamp,+                               tid       :: MVar (ThreadId, ThreadId),+                               lock      :: MVar Lock.Lock}++instance Eq ClientConn where+  (==) c0 c1 = (cid c0) == (cid c1)++-- |A Generic Server+data Server = Server { port       :: Net.PortID, +                       socket     :: IORef (Maybe Net.Socket), +                       clients    :: List ClientConn,+                       cmdList   :: List Message,+                       lastclean  :: TimeStamp,+                       timeout    :: NominalDiffTime,+                       serverLock :: MVar Lock.Lock,+                       cmdTable   :: CmdTable,+                       nextID     :: MVar Integer,+                       cHandler   :: ConnectionHandler,+                       dHandler   :: DisconnectHandler,+                       threads    :: MVar (ThreadId, ThreadId)}++++++{-|+Creates a new server that is not connected to anything.+If a client does not talk to a server for more than 60 seconds+it will be disconnected.+-}+new :: ConnectionHandler -> DisconnectHandler -> Int -> IO Server+new cHandler dHandler pid = do+  socket   <- newIORef Nothing+  clients  <- emptyList+  cmdList <- emptyList+  time <- getCurrentTime+  lastClean <- newMVar time+  lock <- Lock.new+  serverLock <- newMVar lock+  let allowed = 60+  cmdTable <- HT.new+  nextID <- newMVar 0+  threads <- newEmptyMVar+  return $ Server (Net.PortNumber $ fromIntegral pid) socket clients cmdList lastClean allowed serverLock cmdTable nextID cHandler dHandler threads++{-|+Given a server, a command, and a command handler, adds the command to the+server. If the command already exists, it will be overwritten+-}+addCommand :: Server -> String -> CmdHandler -> IO ()+addCommand server cmd handler = HT.insert (cmdTable server) cmd handler++{-|+Starts a server if it is currently not started. Otherwise, does nothing.+-}+start :: Server -> IO ()+start server = Net.withSocketsDo $ do+  maybeSocket <- readIORef $ socket server+  case maybeSocket of+    Nothing -> do +      s <- try $ Net.listenOn (port server) :: IO (Either IOException Net.Socket)+      case s of +        Left e -> debugLn' (serverLock server) $ "The server could not be started: " ++ (show e)+        Right s -> do+          writeIORef (socket server) (Just s)+          rt <- forkIO $ runServer server+          at <- forkIO $ acceptCon server s+          putMVar (threads server) (rt, at)+          return ()+    Just s -> return ()++{-|+Stops a server if it is running sending a disconnect message+to all clients. Otherwise, does nothing.+Any shutdown operations should be run before this is called. +-}+stop :: Server -> IO ()+stop server = Net.withSocketsDo $ do+  maybeSocket <- readIORef $ socket server+  case maybeSocket of+    Nothing -> return ()+    Just s -> do+      clist <- takeAll $ clients server+      mapM_ (disconnect server) (toList clist)+      (rt, at) <- takeMVar (threads server)+      killThread rt+      killThread at+      Net.close s+      writeIORef (socket server) Nothing++{-|+Adds a response message to the queue.+-}+respond :: ClientConn -> String -> IO ()+respond client string = put (msgList client) string++{-|+Broadcasts a message to all clients on the server+-}+broadcast :: Server -> String -> IO ()+broadcast server string = do+  debugLn' (serverLock server) "Reading client list"+  q <- readAll (clients server)+  debugLn' (serverLock server) "Processing client list"+  mapM_ ((flip put string) . msgList) q+  debugLn' (serverLock server) "Message queued."++{-|+Disconnects the client if they are on this server. If+they are not on this server, the results are unspecified.+-}+disconnectClient :: Server -> ClientConn -> IO ()+disconnectClient server client = do+  swapMVar (dead client) True+  clean server++{-|+Returns a list of all clients that are currently connected to the server+-}+clientList :: Server -> IO [ClientConn]+clientList = readAll . clients+++--------------------------------------+-- Helper Functions and Types Begin --+--------------------------------------++type List a = MVar (Seq.Seq a)+type TimeStamp = MVar UTCTime+type CmdTable = HT.BasicHashTable String CmdHandler+type UserTable = HT.BasicHashTable String String+++data Message = Message { cmd    :: String,+                         client :: ClientConn } deriving Eq++{-|              +Creates a new client connection+-}+newConn :: Integer -> Handle -> Net.HostName -> Net.PortNumber -> IO ClientConn+newConn id handle host pid = do+  queue <- emptyList+  dead' <- newMVar False+  tid <- newEmptyMVar+  timestamp <- newEmptyMVar+  lock <- newEmptyMVar+  table <- HT.new+  l <- Lock.new+  let lookup = safeLookup l table+      modify = safeModify l table+  return $ ClientConn id lookup modify handle host pid queue dead' timestamp tid lock++safeLookup :: Lock.Lock -> UserTable -> (String -> IO String)+safeLookup lock usertable = (\key -> do+                                Lock.acquire lock+                                val <- HT.lookup usertable key+                                Lock.release lock+                                return $ case val of+                                    Nothing -> ""+                                    Just x -> x)++safeModify :: Lock.Lock -> UserTable -> (String -> String -> IO ())+safeModify lock usertable = (\key val -> do+                                Lock.acquire lock+                                HT.insert usertable key val+                                Lock.release lock)++++{-| +The main loop for the server. Checks to see if the+server has started, if it has it checks for any clients+who need to be disconnected then processes any commands in its queue.+Every 30 seconds, the server will check to see if a client has disconnected+or timed out and remove those clients from the client list.+After processing the loop continues until the server is stopped.+If there are no commands, it will wait approx. 1/10th of a second+before continuing.+-}+runServer :: Server -> IO ()+runServer server = Net.withSocketsDo $ do+  maybeSocket <- readIORef $ socket server+  case maybeSocket of+    Nothing -> return ()+    Just _ -> do+      checkClean server+      cmds <- takeAll (cmdList server)+      if (cmds == []) +        then delay (1000*100) +        else do+          debugLn' (serverLock server) "Processing Commands..."+          mapM_ (processCommand server) cmds+          debugLn' (serverLock server) "Done."+      runServer server++{-|+Using a servers command table, processess the a message. If+the message cannot be processed, a message is added to its response queue+-}+processCommand :: Server -> Message -> IO ()+processCommand server msg = do+  let commands = words (cmd msg)+  if commands == [] +    then return ()+    else do+      maybeFunction <- HT.lookup (cmdTable server) (head commands)+      case maybeFunction of+        Nothing -> do+          debugLn' (serverLock server) $ "Could not process command: " ++ (cmd msg)+          put (response_queue msg) ("Invalid command: " ++ (cmd msg))+        Just f -> f commands server (client msg)+      where response_queue = msgList . client+{-|+Checks for dead or timed out clients and removes them.+-}+checkClean :: Server -> IO ()+checkClean server = do+  time <- getCurrentTime+  last <- readMVar (lastclean server)+  let passed = diffUTCTime time last+      allowed = timeout server+  if (passed > allowed) +    then do+      swapMVar (lastclean server) time+      clean server+    else return ()++clean :: Server -> IO ()+clean server = do+  let allowed = timeout server+  clist <- takeMVar (clients server)+  (newCList, removed) <- filterM' (timedout server allowed) clist+  putMVar (clients server) (Seq.fromList newCList)+  mapM_ (disconnect server) removed+++-- Helper function for filtering Seq with a pred of a -> IO Bool+filterM' :: Monad m => (a -> m Bool) -> Seq.Seq a -> m ([a],[a])+filterM' pred seq = do+  ls <- filterM pred (toList seq)+  ls' <- filterM not' (toList seq)+  return (ls, ls')+  where not' a = do+          val <- pred a+          return $ not val++-- Helper that checks if a client is timed out or marked dead. If they are+-- they are sent a disconnect message and removed from the  +-- client list+timedout :: Server -> NominalDiffTime -> ClientConn -> IO Bool+timedout server allowed client = do+  time <- getCurrentTime+  last <- readMVar (timestamp client)+  dead' <- readMVar (dead client)+  let passed = diffUTCTime time last+  return $ not $ (passed > allowed) || (dead' == True)++-- Sends a disconnect message to a client, marks it dead+-- and kills any associated threads+disconnect :: Server -> ClientConn -> IO ()+disconnect server client = do+  (dHandler server) server client+  flush server client+  (wio,rio) <- readMVar $ tid client+  killThread wio+  killThread rio+  swapMVar (dead client) True+  return ()++flush :: Server -> ClientConn -> IO ()+flush server client = do+  messages <- takeAll $ msgList client+  mapM_ (hPutStrLn (chandle client)) messages++{-|+Accepts a connection and adds it to the clients list+-}+acceptCon :: Server -> Net.Socket -> IO ()+acceptCon server sock = do+  (handle, host, pid) <- Net.accept sock+  hSetBuffering handle NoBuffering+  id <- takeMVar (nextID server)+  putMVar (nextID server) (id+1)+  conn <- newConn id handle host pid+  time <- getCurrentTime+  putMVar (timestamp conn) time+  lock' <- readMVar $ serverLock server+  putMVar (lock conn) lock'+  put (clients server) conn+  wio <- forkIO $ writeClient conn+  rio <- forkIO $ readClient conn (cmdList server)+  putMVar (tid conn) (wio,rio)+  (cHandler server) server conn+  acceptCon server sock+  +{-+The main loop for receiving input from a client.+Read a whole string input, create a message, queue it for processing, repeat+-}+readClient :: ClientConn -> List Message -> IO ()+readClient client queue = do+  either <- try $ hGetLine (chandle client) :: IO (Either IOException String)+  case either of+    Left e -> do +      swapMVar (dead client) True+      return ()+    Right val -> do+      time <- getCurrentTime+      swapMVar (timestamp client) time+      put queue (Message val client)+      readClient client queue+{-+The main loop for sending output to a client. All messages that are queued+to be sent, are sent. If the queue was empty, the thread sleeps for approx 1/10th+a second+-}+writeClient :: ClientConn -> IO () +writeClient client = do+  queue <- takeAll (msgList client)+  if queue == [] +    then do +      delay (1000*100)+      writeClient client+    else do+      debugLn' (lock client) "Client List non-empty. Writing to client."+      either <- try $ mapM_ (hPutStrLn (chandle client)) queue :: IO (Either IOException ())+      case either of+        Left e -> do+          debugLn' (lock client) $ "Could not read from handle: " ++ (show e)+          swapMVar (dead client) True+          return ()+        Right _ -> writeClient client+++-- Debugging putStrLn that takes a lock such that+-- the output is readable.+putStrLn' :: MVar Lock.Lock -> String -> IO ()+putStrLn' mvar string = do+  lock <- readMVar mvar+  Lock.acquire lock+  putStrLn string+  Lock.release lock+  +hPutStrLn :: Handle -> String -> IO ()+hPutStrLn handle string = ByteS.hPutStrLn handle (ByteS.pack string)++hGetLine :: Handle -> IO String+hGetLine handle = do+  line <- ByteS.hGetLine handle+  return $ ByteS.unpack line++debug = False++debugLn' :: MVar Lock.Lock -> String -> IO ()+debugLn' lock str = if debug then putStrLn' lock str else return ()++emptyList :: IO (List a)+emptyList = newMVar Seq.empty++takeAll :: List a -> IO [a]+takeAll queue = do+  q <- swapMVar queue Seq.empty+  return $ toList q++readAll :: List a -> IO [a]+readAll queue = do+  q <- readMVar queue+  return $ toList q++modifyMVar :: MVar a -> (a -> a) -> IO ()+modifyMVar mvar f = do+  el <- takeMVar mvar+  putMVar mvar (f el)++put :: List a -> a -> IO ()+put queue el = modifyMVar queue (Seq.|> el)  +

@@ -0,0 +1,69 @@+module Network.SimpleServer.Examples.ChatClient(main, run) where+import Network+import System.Environment+import Control.Concurrent+import Control.Concurrent.MVar+import Control.Concurrent.Thread.Delay+import Control.Monad+import System.IO+import Data.Char++-- Attempts to connect to a host on a specified port+-- If successful, a thread is started that prints out+-- incoming data, a thread starts that takes input from+-- standard in, and a thread starts that pings the server+-- every 30 seconds. Once the message "disconnect" is received+-- from the server, each thread stops and the program exits.+run :: HostName -> Int -> IO ()+run host port = do+  handle <- connectTo host (PortNumber (fromIntegral port))+  stopVar <- newEmptyMVar+  ioo <- forkIO $ forever (doOutput handle)+  ioi <- forkIO $ forever (doInput handle stopVar)+  iom <- forkIO $ forever (maintainConnection handle)+  readMVar stopVar+  killThread ioo+  killThread ioi+  killThread iom+  return ()+  +-- Given a handle, takes a line from standard in and+-- sends it to the handle. If the message starts with a '/'+-- it is sent normally, if it does not start with '/' a+-- '/message ' is appended to the front of it before it is+-- sent.+doOutput :: Handle -> IO ()+doOutput handle = do+  msg <- getLine+  case msg of+    msg@('/':_) -> hPutStrLn handle msg+    msg -> hPutStrLn handle $ "/message " ++ msg++-- Given a handle for sending output, reads a line and+-- prints it to stdout. If the input is "disconnected"+-- the mvar is set which allows the main thread to die.+doInput :: Handle -> MVar Bool -> IO ()+doInput handle mvar = do+  string <- hGetLine handle+  putStrLn string+  if string == "disconnected" then putMVar mvar True else return ()++-- Sends the '/ping silent' command to the server+-- every 30 seconds+maintainConnection :: Handle -> IO ()+maintainConnection handle = do+  hPutStrLn handle "/ping silent"+  delay (1000 * 1000 * 30) -- 30 seconds++main = do+  args <- getArgs+  case args of+    [] -> printUsage+    (x:[]) -> printUsage+    (host:port:_) -> if isInt port then run host (read port) else printUsage+                                                   +printUsage :: IO ()                                                   +printUsage = putStrLn "./ChatClient hostname port"++isInt :: [Char] -> Bool+isInt = (== []) . (filter (not . isDigit))

@@ -0,0 +1,136 @@+module Network.SimpleServer.Examples.ChatServer(main, run) where+import Data.Char+import Data.List+import System.Environment++import qualified Network.SimpleServer as S++-- Constants --+-- A Welcome message to send to clients when they connect.+welcomeMessage = "Welcome to the Simple Chat Server.\n" +++                 "Commands:\n" +++                 "/message [message] - Broadcast a message to all users.\n" +++                 "/name [newname] - Change your name to newname.\n" +++                 "/ping - Let's the server know you're still there.\n" ++ +                 "/who - Displays a list of users connected to the server.\n" +++                 "/disconnect - Disconnect from Simple Chat Server.\n"++-- Keys+-- The display name for a ClientConn+username = "username"++-- Handlers++-- The Connection Handler sets a newly connected+-- users username to "user #{cid}" broadcasts+-- that they have connected and then sends them the welcome message+connHandler :: S.ConnectionHandler+connHandler server client = do+  let name = "user #" ++ (show (S.cid client))+      msg = name ++ " connected."+  S.modify client username name+  S.broadcast server msg+  S.respond client welcomeMessage++-- The Disconnection Handler responds to the client "disconnected"+-- Then broadcasts to the room that the user has disconnected+dissHandler :: S.DisconnectHandler+dissHandler server client = do+  name <- S.lookup client username+  let msg = name ++ " disconnected."+  S.respond client "disconnected"+  S.broadcast server msg++-- Commands+  +-- The name command sets the username to the value specified+-- by the user as long as it is not the empty string. If+-- the name is the empty string, the client is notified that+-- the name is not valid. Otherwise, a message is broadcast+-- stating the user changed their name+nameCmd = "/name"+nameHandler :: S.CmdHandler+nameHandler (_:msg) server client = do+  case msg of+    [] -> S.respond client "You did not provide a name to change to."+    msg -> do+      before <- S.lookup client username+      let name = intercalate " " msg+          message = before ++ " is now known as " ++ name+      S.modify client username (intercalate " " msg)+      S.broadcast server message++-- The ping command notifies the server that the user is still connected+-- so they don't time out. If the /ping command is followed by "silent"+-- the server does not respond. Otherwise, the server responds with+-- a received message.+pingCmd = "/ping"+pingHandler :: S.CmdHandler+pingHandler (_:flag) _ client = do+  case flag of+    ("silent":_) -> return ()+    _ -> S.respond client "Ping received."++-- If the message command is received, any text following it is+-- broadcast to all users.+msgCmd = "/message"+msgHandler :: S.CmdHandler+msgHandler (cmd:msg) server client = do+  name <- S.lookup client username+  S.broadcast server $ name ++ "> " ++ (intercalate " " msg)++-- The disconnect command causes the message "Goodbye!" to be sent to+-- the client. Then they are disconnected from the server.+disCmd = "/disconnect"+disHandler :: S.CmdHandler+disHandler _ server client = do+  S.respond client "Goodbye!"+  S.disconnectClient server client+  +-- The who command responds to the client with+-- a list of usernames+whoCmd = "/who"+whoHandler :: S.CmdHandler+whoHandler _ server client = do+  clients <- S.clientList server+  usernames <- mapM (flip S.lookup username) clients+  let message = "Users:\n" ++ (intercalate "\n" usernames)+  S.respond client message++-- Builds a server on the given port, adds the commands+-- starts the server, and waits for the word stop to be entered+run :: Int -> IO ()+run port = do+  server <- S.new connHandler dissHandler port+  S.addCommand server whoCmd whoHandler+  S.addCommand server nameCmd nameHandler+  S.addCommand server disCmd disHandler+  S.addCommand server msgCmd msgHandler+  S.addCommand server pingCmd pingHandler+  S.start server+  putStrLn $ "Chat Server Started on Port: " ++ (show port)+  putStrLn $ "Type 'stop' to stop the server."+  waitStop server+  S.stop server+  putStrLn "Server Stopped"++-- Waits for the word 'stop' to be entered+waitStop :: S.Server -> IO ()+waitStop server = do+  string <- getLine+  case string of+    "stop" -> return ()+    _ -> waitStop server+  +-- Starts a server on the specified port or prints the usage message+main = do+  args <- getArgs+  case args of+    [] -> printUsage+    (x:_) -> if isInt x then (return (read x)) >>= run else printUsage++printUsage :: IO ()+printUsage = putStrLn "Usage ./ChatServer [port]"++isInt :: [Char] -> Bool+isInt = (== []) . (filter (not . isDigit))

@@ -0,0 +1,2 @@+simple-server+=============

@@ -0,0 +1,5 @@+module Main where++import Distribution.Simple++main = defaultMain

@@ -0,0 +1,20 @@+Name:           simple-server+Version:        0.0.1+License:        GPL+License-File:   LICENSE+Author:	        Joseph Collard+Stability:      experimental+Maintainer:	jcollard@unm.edu+Category:       Network+Synopsis:       Simple Server interface+Description:    This library provides a very simple interface for creating a server that sends and recieves ByteString messages and attempts to remove concurrency so the programmer can focus on the functionality of the server. A simple ChatServer example is available in the Examples module+Cabal-Version:  >= 1.4+Build-Type:     Simple++Library+  Build-Depends:  base>=4 && <5, bytestring>=0.9.2.1, concurrent-extra>=0.7.0.5, hashtables>=1.0.1.7, time>=1.4.0.2, containers>=0.4.2.1, network>=2.4.1.0, unbounded-delays>=0.1.0.5+  Extensions:     ConstraintKinds+  Exposed-Modules:+                  Network.SimpleServer+                  Network.SimpleServer.Examples.ChatClient+                  Network.SimpleServer.Examples.ChatServer