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But first, please read +. diff --git a/Network/SimpleServer.hs b/Network/SimpleServer.hs new file mode 100644 --- /dev/null +++ b/Network/SimpleServer.hs @@ -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) + diff --git a/Network/SimpleServer/Examples/ChatClient.hs b/Network/SimpleServer/Examples/ChatClient.hs new file mode 100644 --- /dev/null +++ b/Network/SimpleServer/Examples/ChatClient.hs @@ -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)) diff --git a/Network/SimpleServer/Examples/ChatServer.hs b/Network/SimpleServer/Examples/ChatServer.hs new file mode 100644 --- /dev/null +++ b/Network/SimpleServer/Examples/ChatServer.hs @@ -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)) diff --git a/README.md b/README.md new file mode 100644 --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +simple-server +============= diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,5 @@ +module Main where + +import Distribution.Simple + +main = defaultMain diff --git a/simple-server.cabal b/simple-server.cabal new file mode 100644 --- /dev/null +++ b/simple-server.cabal @@ -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