path: root/Presence/XMPPServer.hs

{-# LANGUAGE CPP #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RankNTypes #-}
module XMPPServer
    ( xmppServer
    , ConnectionKey(..)
    , XMPPServerParameters(..)
    , XMPPServer
    , addPeer
    , StanzaWrap(..)
    , Stanza(..)
    , StanzaType(..)
    , StanzaOrigin(..)
    , cloneStanza
    , LangSpecificMessage(..)
    , peerKeyToText
    , peerKeyToResolvedName
    , addrToText
    , sendModifiedStanzaToPeer
    , sendModifiedStanzaToClient
    ) where

import Debug.Trace
import Control.Monad.Trans.Resource (runResourceT)
import Control.Monad.Trans (lift)
import Control.Monad.IO.Class (MonadIO, liftIO)
import Control.Monad.Fix (fix)
import Control.Monad
import Control.Concurrent (forkIO)
import Control.Concurrent.STM
-- import Control.Concurrent.STM.TChan
import Network.Socket
import Text.Printf
import System.Posix.Signals
import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as Strict8
-- import qualified Data.ByteString.Lazy.Char8 as Lazy8
import Data.Int (Int8)

import Data.Conduit
import qualified Data.Conduit.List as CL
import qualified Data.Conduit.Binary as CB
import Data.Conduit.Blaze (builderToByteStringFlush)

import qualified Text.XML.Stream.Render as XML
import qualified Text.XML.Stream.Parse as XML
import Data.XML.Types as XML
import Data.Maybe
import Data.Monoid ( (<>) )
import Data.Text (Text)
import qualified Data.Text as Text (pack,unpack)
import Data.Char (toUpper)
import Data.Map (Map)
import qualified Data.Map as Map
import Data.Set (Set, (\\) )
import qualified Data.Set as Set
import qualified System.Random 
import qualified Network.BSD as BSD
import Data.Void (Void)

import GetHostByAddr (getHostByAddr)
import qualified Control.Concurrent.STM.UpdateStream as Slotted
import Nesting
import Server
import EventUtil
import ControlMaybe

withPort :: SockAddr -> Int -> SockAddr
withPort (SockAddrInet _ a)      port = SockAddrInet (toEnum port) a
withPort (SockAddrInet6 _ a b c) port = SockAddrInet6 (toEnum port) a b c


peerport :: PortNumber
peerport = 5269
clientport :: PortNumber
clientport = 5222

my_uuid :: Text
my_uuid = "154ae29f-98f2-4af4-826d-a40c8a188574"

data ConnectionKey
       = PeerKey { callBackAddress :: SockAddr }
       | ClientKey { localAddress :: SockAddr }
 deriving (Show, Ord, Eq)

data JabberShow = Offline
                | ExtendedAway
                | Away
                | DoNotDisturb
                | Available
                | Chatty
 deriving (Show,Enum,Ord,Eq,Read)

data MessageThread = MessageThread { 
        msgThreadParent  :: Maybe Text,
        msgThreadContent :: Text
    }
  deriving (Show,Eq)

data LangSpecificMessage =
    LangSpecificMessage { msgBody :: Maybe Text
                        , msgSubject :: Maybe Text
                        }
  deriving (Show,Eq)

data RosterEventType
    = RequestedSubscription
    | NewBuddy -- preceded by PresenceInformSubscription True
    | RemovedBuddy -- preceded by PresenceInformSubscription False
    | PendingSubscriber -- same as PresenceRequestSubscription
    | NewSubscriber
    | RejectSubscriber
 deriving (Show,Read,Ord,Eq,Enum)

data StanzaType
    = Unrecognized
    | Ping
    | Pong
    | RequestResource (Maybe Text)
    | SetResource
    | SessionRequest
    | UnrecognizedQuery Name
    | RequestRoster
    | Roster
    | RosterEvent { rosterEventType :: RosterEventType
                  , rosterUser :: Text
                  , rosterContact :: Text }
    | Error
    | PresenceStatus { presenceShow :: JabberShow
                     , presencePriority :: Maybe Int8
                     , presenceStatus :: [(Lang,Text)]
                     }
    | PresenceInformError
    | PresenceInformSubscription Bool
    | PresenceRequestStatus
    | PresenceRequestSubscription Bool
    | Message { msgThread :: Maybe MessageThread
              , msgLangMap :: [(Lang,LangSpecificMessage)]
              }
 deriving Show

data StanzaOrigin = LocalPeer | NetworkOrigin ConnectionKey (TChan Stanza)

data StanzaWrap a = Stanza
    { stanzaType :: StanzaType
    , stanzaId :: Maybe Text
    , stanzaTo :: Maybe Text
    , stanzaFrom :: Maybe Text
    , stanzaChan :: a
    , stanzaClosers ::  TVar (Maybe [XML.Event])
    , stanzaInterrupt :: TMVar ()
    , stanzaOrigin :: StanzaOrigin
    }

type Stanza = StanzaWrap (TChan XML.Event)

data XMPPServerParameters =
    XMPPServerParameters
    { xmppChooseResourceName :: ConnectionKey -> SockAddr -> Maybe Text -> IO Text
    , xmppTellMyNameToClient :: IO Text
    , xmppTellMyNameToPeer :: SockAddr -> IO Text
    , xmppTellClientHisName :: ConnectionKey -> IO Text
    , xmppTellPeerHisName :: ConnectionKey -> IO Text
    , xmppNewConnection :: ConnectionKey -> SockAddr -> TChan Stanza -> IO ()
    , xmppEOF :: ConnectionKey -> IO ()
    , xmppRosterBuddies      :: ConnectionKey -> IO [Text]
    , xmppRosterSubscribers  :: ConnectionKey -> IO [Text]
    , xmppRosterSolicited    :: ConnectionKey -> IO [Text]
    , xmppRosterOthers       :: ConnectionKey -> IO [Text]
    , xmppSubscribeToRoster :: ConnectionKey -> IO ()
    -- , xmppLookupClientJID :: ConnectionKey -> IO Text
    , xmppTellClientNameOfPeer :: ConnectionKey -> IO Text
    , xmppDeliverMessage :: (IO ()) -> Stanza -> IO ()
    , xmppInformClientPresence :: ConnectionKey -> Stanza -> IO ()
    }


-- TODO: http://xmpp.org/rfcs/rfc6120.html#rules-remote-error
-- client connection
-- socat script to send stanza fragment
-- copyToChannel can keep a stack of closers to append to finish-off a stanza
-- the TMVar () from forkConnection can be passed and with a stanza to detect interruption

addrToText :: SockAddr -> Text
addrToText (addr@(SockAddrInet _ _)) = Text.pack $ stripColon (show addr)
 where stripColon s = pre where (pre,port) = break (==':') s
addrToText (addr@(SockAddrInet6 _ _ _ _)) = Text.pack $ stripColon (show addr)
 where stripColon s = if null bracket then pre else pre ++ "]"
          where
            (pre,bracket) = break (==']') s

peerKeyToText :: ConnectionKey -> Text
peerKeyToText (PeerKey { callBackAddress=addr }) = addrToText addr
peerKeyToText (ClientKey { localAddress=addr }) = "ErrorClIeNt0"

peerKeyToResolvedName :: ConnectionKey -> IO Text
peerKeyToResolvedName k@(ClientKey { localAddress=addr }) = return "ErrorClIeNt1"
peerKeyToResolvedName k@(PeerKey { callBackAddress=addr }) = do
    mname <- handleIO_ (return Nothing) $ do
        ent <- getHostByAddr addr --  AF_UNSPEC addr
        let names = BSD.hostName ent : BSD.hostAliases ent
        return $ listToMaybe names
    return $ maybe (peerKeyToText k) Text.pack mname 


wlog :: String -> IO ()
wlog s = putStrLn s

wlogb :: ByteString -> IO ()
wlogb s = Strict8.putStrLn s

xmlStream :: ReadCommand -> WriteCommand -> ( Source IO XML.Event
                                            , Sink (Flush XML.Event) IO () )
xmlStream conread conwrite = (xsrc,xsnk)
 where
    xsrc = src $= XML.parseBytes XML.def
    xsnk = -- XML.renderBytes XML.def =$ snk
        XML.renderBuilderFlush XML.def 
        =$= builderToByteStringFlush 
        =$= discardFlush 
        =$ snk
      where
        discardFlush :: Monad m => ConduitM (Flush a) a m ()
        discardFlush = awaitForever $ \x -> do
            let unchunk (Chunk a) = a
                ischunk (Chunk _) = True
                ischunk _         = False
            when (ischunk x) $ yield (unchunk x)

    src = do
        v <- lift conread
        maybe (return ()) -- lift . wlog $ "conread: Nothing")
              (\v -> yield v >> src)
              v
    snk = awaitForever $ liftIO . conwrite
        

type FlagCommand = STM Bool
type ReadCommand = IO (Maybe ByteString)
type WriteCommand = ByteString -> IO Bool

cloneStanza :: StanzaWrap (TChan a) -> STM (StanzaWrap (TChan a))
cloneStanza stanza = do
    dupped <- cloneTChan (stanzaChan stanza)
    return stanza { stanzaChan = dupped }

copyToChannel
  :: MonadIO m =>
     (Event -> a) -> TChan a -> TVar (Maybe [Event]) -> ConduitM Event Event m ()
copyToChannel f chan closer_stack = awaitForever copy
 where
    copy x = do 
        liftIO . atomically $ writeTChan chan (f x)
        case x of
            EventBeginDocument {} -> do
                let clsr = closerFor x
                liftIO . atomically $
                    modifyTVar' closer_stack (fmap (clsr:))
            EventEndDocument {} -> do
                liftIO . atomically $
                    modifyTVar' closer_stack (fmap (drop 1))
            _ -> return ()
        yield x


prettyPrint :: ByteString -> ConduitM Event Void IO ()
prettyPrint prefix = 
        XML.renderBytes (XML.def { XML.rsPretty=True })
        =$= CB.lines 
        =$ CL.mapM_ (wlogb . (prefix <>))

swapNamespace :: Monad m => Text -> Text -> ConduitM Event Event m ()
swapNamespace old new = awaitForever swapit
 where
    swapit (EventBeginElement n as) | nameNamespace n==Just old =
        yield $ EventBeginElement (n { nameNamespace = Just new }) as
    swapit (EventEndElement n) | nameNamespace n==Just old =
        yield $ EventEndElement (n { nameNamespace = Just new })
    swapit x = yield x

fixHeaders :: Monad m => Stanza -> ConduitM Event Event m ()
fixHeaders Stanza { stanzaTo=mto, stanzaFrom=mfrom } = do
    x <- await
    maybe (return ()) f x
 where
    f (EventBeginElement n as) = do yield $ EventBeginElement n (update as)
                                    awaitForever yield
    f x = yield x >> awaitForever yield
    update as = as''
     where
        as' = maybe as (\to->attr "to" to:as) mto
        as'' = maybe as' (\from->attr "from" from:as') mfrom
    
conduitToChan
  :: Conduit () IO Event
     -> IO (TChan Event, TVar (Maybe [Event]), TMVar a)
conduitToChan c = do
    chan <- atomically newTChan
    clsrs <- atomically $ newTVar (Just [])
    quitvar <- atomically $ newEmptyTMVar
    forkIO $ do
        c =$= copyToChannel id chan clsrs $$ awaitForever (const $ return ())
        atomically $ writeTVar clsrs Nothing
    return (chan,clsrs,quitvar)

ioWriteChan :: MonadIO m => TChan a -> a -> m ()
ioWriteChan c v = liftIO . atomically $ writeTChan c v

stanzaToConduit :: MonadIO m => Stanza -> ConduitM i Event m ()
stanzaToConduit stanza = do
    let xchan = stanzaChan stanza
        xfin = stanzaClosers stanza
        rdone = stanzaInterrupt stanza
        loop = return ()
    fix $ \inner -> do
        what <- liftIO . atomically $ foldr1 orElse
            [readTChan xchan >>= \xml -> return $ do
                yield xml -- atomically $ Slotted.push slots Nothing xml
                inner
            ,do mb <- readTVar xfin
                cempty <- isEmptyTChan xchan
                if isNothing mb
                    then if cempty then return loop else retry
                    else do done <- tryReadTMVar rdone
                            check (isJust done)
                            trace "todo: send closers" retry
            ,do isEmptyTChan xchan >>= check
                readTMVar rdone
                return (return ())]
        what


sendModifiedStanzaToPeer :: Stanza -> TChan Stanza -> IO ()
sendModifiedStanzaToPeer stanza chan = do
    (echan,clsrs,quitvar) <- conduitToChan c
    ioWriteChan chan
        stanza  { stanzaChan = echan
                , stanzaClosers = clsrs
                , stanzaInterrupt = quitvar
                -- TODO id? origin?
                }
 where
    c = stanzaToConduit stanza =$= swapNamespace "jabber:client" "jabber:server" =$= fixHeaders stanza

sendModifiedStanzaToClient :: Stanza -> TChan Stanza -> IO ()
sendModifiedStanzaToClient stanza chan = do
    (echan,clsrs,quitvar) <- conduitToChan c
    ioWriteChan chan
        stanza  { stanzaChan = echan
                , stanzaClosers = clsrs
                , stanzaInterrupt = quitvar
                -- TODO id? origin?
                }
 where
    c = stanzaToConduit stanza =$= swapNamespace "jabber:server" "jabber:client" =$= fixHeaders stanza

-- id,to, and from are taken as-is from reply list
-- todo: this should probably be restricted to IO monad
sendReply :: (Functor m, MonadIO m) => TMVar () -> StanzaType -> [Event] -> TChan Stanza -> m ()
sendReply donevar stype reply replychan = do
    if null reply then return ()
    else do
    let stanzaTag = head reply
        mid   = lookupAttrib "id" (tagAttrs stanzaTag)
        mfrom = lookupAttrib "from" (tagAttrs stanzaTag)
        mto = lookupAttrib "to" (tagAttrs stanzaTag)
    replyStanza <- liftIO . atomically $ do
        replyChan <- newTChan
        replyClsrs <- newTVar (Just [])
        return Stanza { stanzaType = stype
                      , stanzaId = mid
                      , stanzaTo = mto      -- as-is from reply list
                      , stanzaFrom = mfrom  -- as-is from reply list
                      , stanzaChan = replyChan
                      , stanzaClosers = replyClsrs
                      , stanzaInterrupt = donevar
                      , stanzaOrigin = LocalPeer
                      }
    ioWriteChan replychan replyStanza
    void . liftIO . forkIO $ do
        mapM_ (ioWriteChan $ stanzaChan replyStanza) reply
        liftIO . atomically $ writeTVar (stanzaClosers replyStanza) Nothing
        -- liftIO $ wlog "finished reply stanza"

grokStanzaIQGet :: Monad m => XML.Event -> NestingXML o m (Maybe StanzaType)
grokStanzaIQGet stanza = do
    mtag <- nextElement 
    flip (maybe $ return Nothing)  mtag $ \tag -> do
    case tagName tag of
        "{urn:xmpp:ping}ping" -> return $ Just Ping
        "{jabber:iq:roster}query" -> return $ Just RequestRoster
        name -> return . Just $ UnrecognizedQuery name

grokStanzaIQResult :: Monad m => XML.Event -> NestingXML o m (Maybe StanzaType)
grokStanzaIQResult stanza = do
    mtag <- nextElement 
    flip (maybe $ return (Just Pong))  mtag $ \tag -> do
    case tagName tag of
        _ -> return Nothing

grokStanzaIQSet :: XML.Event -> NestingXML o IO (Maybe StanzaType)
grokStanzaIQSet stanza = do
    mtag <- nextElement 
    flip (maybe $ return Nothing)  mtag $ \tag -> do
    case tagName tag of
        "{urn:ietf:params:xml:ns:xmpp-bind}bind" -> do
            mchild <- nextElement
            case fmap tagName mchild of
                Just "{urn:ietf:params:xml:ns:xmpp-bind}resource" -> do
                    rsc <- XML.content -- TODO: MonadThrow???
                    return . Just $ RequestResource (Just rsc)
                Just _ -> return Nothing
                Nothing -> return . Just $ RequestResource Nothing
        "{urn:ietf:params:xml:ns:xmpp-session}session" -> do
            return $ Just SessionRequest
        _ -> return Nothing


{-
C->Unrecognized <iq
C->Unrecognized   type="set"
C->Unrecognized   id="purpleae62d88f"
C->Unrecognized   xmlns="jabber:client">
C->Unrecognized     <bind xmlns="urn:ietf:params:xml:ns:xmpp-bind"/>
C->Unrecognized </iq>
-}
chanContents :: TChan x -> IO [x]
chanContents ch = do
        x  <- atomically $ do
            bempty <- isEmptyTChan ch
            if bempty
                then return Nothing
                else fmap Just $ readTChan ch
        maybe (return [])
              (\x -> do
                xs <- chanContents ch
                return (x:xs))
              x


parsePresenceStatus
  :: ( MonadThrow m
     , MonadIO m
     ) => Text -> NestingXML o m (Maybe StanzaType)
parsePresenceStatus ns = do

    let toStat "away" = Away
        toStat "xa"   = ExtendedAway
        toStat "dnd"  = DoNotDisturb
        toStat "chat" = Chatty

    showv <- liftIO . atomically $ newTVar Available
    priov <- liftIO . atomically $ newTVar Nothing
    statusv <- liftIO . atomically $ newTChan
    fix $ \loop -> do
        mtag <- nextElement
        flip (maybe $ return ()) mtag $ \tag -> do
        when (nameNamespace (tagName tag) == Just ns) $ do
            case nameLocalName (tagName tag) of
                "show" -> do t <- XML.content
                             liftIO . atomically $ writeTVar showv (toStat t)
                "priority" -> do t <- XML.content
                                 liftIO . handleIO_ (return ()) $ do
                                 prio <- readIO (Text.unpack t)
                                 atomically $ writeTVar priov (Just prio)
                "status" -> do t <- XML.content
                               lang <- xmlLang
                               ioWriteChan statusv (maybe "" id lang,t)
                _ -> return ()
        loop
    show <- liftIO . atomically $ readTVar showv
    prio <- liftIO . atomically $ readTVar priov
    status <- liftIO $ chanContents statusv -- Could use unsafeInterleaveIO to
                                            -- avoid multiple passes, but whatever.
    return . Just $ PresenceStatus { presenceShow = show
                                   , presencePriority = prio
                                   , presenceStatus = status
                                   }
grokPresence
  :: ( MonadThrow m
     , MonadIO m
     ) => Text -> XML.Event -> NestingXML o m (Maybe StanzaType)
grokPresence ns stanzaTag = do
    let typ = lookupAttrib "type" (tagAttrs stanzaTag)
    case typ of
        Nothing -> parsePresenceStatus ns
        Just "unavailable" -> fmap (fmap (\p -> p {presenceShow=Offline}))
                                   $ parsePresenceStatus ns
        Just "error" -> return . Just $ PresenceInformError
        Just "unsubscribed" -> return . Just $ PresenceInformSubscription False
        Just "subscribed"   -> return . Just $ PresenceInformSubscription True
        Just "probe" -> return . Just $ PresenceRequestStatus
        Just "unsubscribe" -> return . Just $ PresenceRequestSubscription False
        Just "subscribe"   -> return . Just $ PresenceRequestSubscription True
        _ -> return Nothing

parseMessage
  :: ( MonadThrow m
     , MonadIO m
     ) => Text -> XML.Event -> NestingXML o m StanzaType
parseMessage ns stanza = do
    let bodytag = Name { nameNamespace = Just ns
                       , nameLocalName = "body"
                       , namePrefix = Nothing }
        subjecttag = Name { nameNamespace = Just ns
                          , nameLocalName = "subject"
                          , namePrefix = Nothing }
        threadtag = Name { nameNamespace = Just ns
                         , nameLocalName = "thread"
                         , namePrefix = Nothing }
    let emptyMsg = LangSpecificMessage { msgBody=Nothing, msgSubject=Nothing }
        parseChildren (th,cmap) = do
            child <- nextElement
            lvl <- nesting
            xmllang <- xmlLang 
            let lang = maybe "" id xmllang
            let c = maybe emptyMsg id (Map.lookup lang cmap)
            -- log $ " child: "<> bshow child
            case child of
                Just tag | tagName tag==bodytag
                                    -> do
                                        txt <- XML.content
                                        awaitCloser lvl
                                        parseChildren (th,Map.insert lang (c { msgBody=Just txt }) cmap)
                Just tag | tagName tag==subjecttag
                                    -> do
                                        txt <- XML.content
                                        awaitCloser lvl
                                        parseChildren (th,Map.insert lang (c { msgSubject=Just txt }) cmap)
                Just tag | tagName tag==threadtag
                                    -> do
                                        txt <- XML.content
                                        awaitCloser lvl
                                        parseChildren (th {msgThreadContent=txt},cmap)
                Just tag -> do
                            -- let nm    = tagName tag
                            --    attrs = tagAttrs tag
                            --    -- elems = msgElements c
                            -- txt <- XML.content
                            awaitCloser lvl
                            parseChildren (th,Map.insert lang c cmap)
                Nothing -> return (th,cmap)
    (th,langmap) <- parseChildren ( MessageThread {msgThreadParent=Nothing, msgThreadContent=""}
                                  , Map.empty )
    return Message { 
        msgLangMap = Map.toList langmap,
        msgThread = if msgThreadContent th/="" then Just th else Nothing
    }

grokMessage
  :: ( MonadThrow m
     , MonadIO m
     ) => Text -> XML.Event -> NestingXML o m (Maybe StanzaType)
grokMessage ns stanzaTag = do
    t <- parseMessage ns stanzaTag
    return $ Just t



grokStanza
  ::  Text -> XML.Event -> NestingXML o IO (Maybe StanzaType)
grokStanza "jabber:server" stanzaTag = 
            case () of
                _ | stanzaTag `isServerIQOf` "get" -> grokStanzaIQGet stanzaTag
                _ | stanzaTag `isServerIQOf` "result" -> grokStanzaIQResult stanzaTag
                _ | tagName stanzaTag == "{jabber:server}presence" -> grokPresence "jabber:server" stanzaTag
                _ | tagName stanzaTag == "{jabber:server}message" -> grokMessage "jabber:server" stanzaTag
                _ -> return $ Just Unrecognized

grokStanza "jabber:client" stanzaTag = 
            case () of
                _ | stanzaTag `isClientIQOf` "get" -> grokStanzaIQGet stanzaTag
                _ | stanzaTag `isClientIQOf` "set" -> grokStanzaIQSet stanzaTag
                _ | stanzaTag `isClientIQOf` "result" -> grokStanzaIQResult stanzaTag
                _ | tagName stanzaTag == "{jabber:client}presence" -> grokPresence "jabber:client" stanzaTag
                _ | tagName stanzaTag == "{jabber:client}message" -> grokMessage "jabber:client" stanzaTag
                _ -> return $ Just Unrecognized

mkname :: Text -> Text -> XML.Name
mkname namespace name = (Name name (Just namespace) Nothing)

makePong :: Text -> Maybe Text -> Text -> Text -> [XML.Event]
makePong namespace mid to from =
       -- Note: similar to session reply
       [ EventBeginElement (mkname namespace "iq")
         $(case mid of
               Just c -> (("id",[ContentText c]):)
               _      -> id)
               [ attr "type" "result"
               , attr "to"   to
               , attr "from" from
               ]
       , EventEndElement (mkname namespace "iq")
       ]


xmppInbound :: Server ConnectionKey SockAddr
                -> XMPPServerParameters
                -> ConnectionKey
                -> SockAddr
                -> FlagCommand 
                -> Source IO XML.Event
                -> TChan Stanza
                -> TChan Stanza
                -> TMVar ()
                -> Sink XML.Event IO ()
xmppInbound sv xmpp k laddr pingflag src stanzas output donevar = doNestingXML $ do
    let (namespace,tellmyname,tellyourname) = case k of
            ClientKey {} -> ( "jabber:client"
                            , xmppTellMyNameToClient xmpp
                            , xmppTellClientHisName xmpp k
                            )
            PeerKey {} -> ( "jabber:server"
                          , xmppTellMyNameToPeer xmpp laddr
                          , xmppTellPeerHisName xmpp k
                          )
    me <- liftIO tellmyname
    you <- liftIO tellyourname
    withXML $ \begindoc -> do
    when (begindoc==EventBeginDocument) $ do
    whenJust nextElement $ \xml -> do
    withJust (elementAttrs "stream" xml) $ \stream_attrs -> do
    fix $ \loop -> do
    -- liftIO . wlog $ "waiting for stanza."
    (chan,clsrs) <- liftIO . atomically $
        liftM2 (,) newTChan (newTVar (Just []))
    whenJust nextElement $ \stanzaTag -> do
        stanza_lvl <- nesting
        liftIO . atomically $ do
            writeTChan chan stanzaTag
            modifyTVar' clsrs (fmap (closerFor stanzaTag:))
        copyToChannel id chan clsrs =$= do
          let mid   = lookupAttrib "id" (tagAttrs stanzaTag)
              mfrom = lookupAttrib "from" (tagAttrs stanzaTag)
              mto = lookupAttrib "to" (tagAttrs stanzaTag)
          dispatch <- grokStanza namespace stanzaTag
          let unrecog = do
                let stype = Unrecognized
                s <- liftIO . atomically $ do
                      return Stanza
                              { stanzaType = stype
                              , stanzaId = mid
                              , stanzaTo = mto
                              , stanzaFrom = mfrom
                              , stanzaChan = chan
                              , stanzaClosers = clsrs
                              , stanzaInterrupt = donevar
                              , stanzaOrigin = NetworkOrigin k output
                              }
                ioWriteChan stanzas s
          flip (maybe $ unrecog) dispatch $ \dispatch -> 
            case dispatch of
              -- Checking that the to-address matches this server.
              -- Otherwise it could be a client-to-client ping or a
              -- client-to-server for some other server.
              -- For now, assuming its for the immediate connection.
              Ping | mto==Just me || mto==Nothing -> do
                let pongto = maybe you id mfrom
                    pongfrom = maybe me id mto
                    pong = makePong namespace mid pongto pongfrom
                sendReply donevar Pong pong output
#ifdef PINGNOISE
                -- TODO: Remove this, it is only to generate a debug print
                ioWriteChan stanzas Stanza
                            { stanzaType = Ping
                            , stanzaId = mid
                            , stanzaTo = mto
                            , stanzaFrom = mfrom
                            , stanzaChan = chan
                            , stanzaClosers = clsrs
                            , stanzaInterrupt = donevar
                            , stanzaOrigin = NetworkOrigin k output
                            }
#endif
              stype -> ioWriteChan stanzas Stanza
                            { stanzaType = stype
                            , stanzaId = mid
                            , stanzaTo = mto
                            , stanzaFrom = mfrom
                            , stanzaChan = chan
                            , stanzaClosers = clsrs
                            , stanzaInterrupt = donevar
                            , stanzaOrigin = NetworkOrigin k output
                            }
          awaitCloser stanza_lvl
        liftIO . atomically $ writeTVar clsrs Nothing
        loop
    

while :: IO Bool -> IO a -> IO [a]
while cond body = do
    b <- cond
    if b then do x <- body
                 xs <- while cond body
                 return (x:xs)
         else return []

readUntilNothing :: TChan (Maybe x) -> IO [x]
readUntilNothing ch = do
        x  <- atomically $ readTChan ch
        maybe (return [])
              (\x -> do
                xs <- readUntilNothing ch
                return (x:xs))
              x


streamFeatures :: Text -> [XML.Event]
streamFeatures "jabber:client" =
    [ EventBeginElement (streamP "features") []
    , EventBeginElement "{urn:ietf:params:xml:ns:xmpp-bind}bind" []
    , EventEndElement "{urn:ietf:params:xml:ns:xmpp-bind}bind"

    {-
    -- , "  <session xmlns='urn:ietf:params:xml:ns:xmpp-session'/>"
    , " <mechanisms xmlns='urn:ietf:params:xml:ns:xmpp-sasl'>"
    -- , " <mechanism>DIGEST-MD5</mechanism>"
    , " <mechanism>PLAIN</mechanism>"
    , " </mechanisms> "
    -}

    , EventEndElement (streamP "features")
    ]
streamFeatures "jabber:server" =
    []


greet' :: Text -> Text -> [XML.Event]
greet' namespace host =
    [ EventBeginDocument
    , EventBeginElement (streamP "stream")
        [("from",[ContentText host])
        ,("id",[ContentText "someid"])
        ,("xmlns",[ContentText namespace])
        ,("xmlns:stream",[ContentText "http://etherx.jabber.org/streams"])
        ,("version",[ContentText "1.0"])
        ]
    ] ++ streamFeatures namespace

consid :: Maybe Text -> [(Name, [Content])] -> [(Name, [Content])]
consid Nothing = id
consid (Just sid) = (("id",[ContentText sid]):)


data XMPPState
    = PingSlot
 deriving (Eq,Ord)

makePing :: Text -> Maybe Text -> Text -> Text -> [XML.Event]
makePing namespace mid to from = 
       [ EventBeginElement (mkname namespace "iq")
         $ (case mid of
            Just c -> (("id",[ContentText c]):)
            _      -> id               )
            [ ("type",[ContentText "get"])
            , attr "to"   to
            , attr "from" from
            ]
       , EventBeginElement "{urn:xmpp:ping}ping" []
       , EventEndElement "{urn:xmpp:ping}ping"
       , EventEndElement $ mkname namespace "iq"]

iq_bind_reply :: Maybe Text -> Text -> [XML.Event]
iq_bind_reply mid jid =
    [ EventBeginElement "{jabber:client}iq" (consid mid [("type",[ContentText "result"])])
    , EventBeginElement "{urn:ietf:params:xml:ns:xmpp-bind}bind"
        [("xmlns",[ContentText "urn:ietf:params:xml:ns:xmpp-bind"])]
    , EventBeginElement "{urn:ietf:params:xml:ns:xmpp-bind}jid" []
    , EventContent (ContentText jid)
    , EventEndElement "{urn:ietf:params:xml:ns:xmpp-bind}jid"
    , EventEndElement  "{urn:ietf:params:xml:ns:xmpp-bind}bind"
    , EventEndElement "{jabber:client}iq"
    ]

iq_session_reply :: Maybe Text -> Text -> [XML.Event]
iq_session_reply mid host =
    -- Note: similar to Pong
    [ EventBeginElement "{jabber:client}iq" 
        (consid mid [("from",[ContentText host])
                    ,("type",[ContentText "result"])
                    ])
    , EventEndElement "{jabber:client}iq"
    ]

iq_service_unavailable :: Maybe Text -> Text -> XML.Name -> [XML.Event]
iq_service_unavailable mid host {- mjid -} req =
    [ EventBeginElement "{jabber:client}iq" 
        (consid mid [("type",[ContentText "error"])
                    -- , TODO: set "from" if isJust mjid
                    ])
    , EventBeginElement req []
    , EventEndElement req
    , EventBeginElement "{jabber:client}error" [("type",[ContentText "cancel"])]
    , EventBeginElement "{urn:ietf:params:xml:ns:xmpp-stanzas}service-unavailable" []
    , EventEndElement "{urn:ietf:params:xml:ns:xmpp-stanzas}service-unavailable"
    , EventEndElement "{jabber:client}error"
    , EventEndElement "{jabber:client}iq"
    ]


wrapStanzaList :: [XML.Event] -> STM [Either (StanzaWrap XML.Event) XML.Event]
wrapStanzaList xs = do
    wrap <- do
        clsrs <- newTVar Nothing
        donev <- newTMVar ()
        return $ \ x ->
            Stanza { stanzaType = Unrecognized
                   , stanzaId = mid
                   , stanzaTo = mto
                   , stanzaFrom = mfrom
                   , stanzaClosers = clsrs
                   , stanzaInterrupt = donev
                   , stanzaOrigin = LocalPeer
                   , stanzaChan = x
                   }
    return $ map (Left . wrap) (take 1 xs) ++ map Right (drop 1 xs)
  where
    m = listToMaybe xs
    mto = m >>= lookupAttrib "to" . tagAttrs
    mfrom = m >>= lookupAttrib "from" . tagAttrs
    mid = m >>= lookupAttrib "id" . tagAttrs

wrapStanzaConduit :: Monad m => StanzaWrap a -> ConduitM Event (Either (StanzaWrap Event) Event) m ()
wrapStanzaConduit stanza = do
    mfirst <- await
    flip (maybe $ return ()) mfirst $ \first -> do
    yield . Left $ stanza { stanzaChan = first }
    awaitForever $ yield . Right



{-
greet namespace =
    [ EventBeginDocument
    , EventBeginElement (streamP "stream")
        [ attr "xmlns"   namespace
        , attr "version" "1.0"
        ]
    ]
-}

goodbye :: [XML.Event]
goodbye = 
    [ EventEndElement (streamP "stream")
    , EventEndDocument
    ]

forkConnection :: Server ConnectionKey SockAddr
                -> XMPPServerParameters
                -> ConnectionKey
                -> SockAddr
                -> FlagCommand
                -> Source IO XML.Event
                -> Sink (Flush XML.Event) IO ()
                -> TChan Stanza
                ->  IO (TChan Stanza)
forkConnection sv xmpp k laddr pingflag src snk stanzas = do
    let (namespace,tellmyname) = case k of
                        ClientKey {} -> ("jabber:client", xmppTellMyNameToClient xmpp)
                        PeerKey {} -> ("jabber:server",xmppTellMyNameToPeer xmpp laddr)
    me <- tellmyname
    rdone <- atomically newEmptyTMVar
    let isStarter (Left _) = True
        isStarter (Right e) | isEventBeginElement e = True
        isStarter _ = False
        isStopper (Left _) = False
        isStopper (Right e) | isEventEndElement e = True
        isStopper _ = False
    slots <- atomically $ Slotted.new isStarter isStopper
    needsFlush <- atomically $ newTVar False
    lastStanza <- atomically $ newTVar Nothing
    nesting <- atomically $ newTVar 0
    let _ = slots :: Slotted.UpdateStream XMPPState (Either (StanzaWrap XML.Event) XML.Event)
    let greet_src = do
            CL.sourceList (greet' namespace me) =$= CL.map Chunk
            yield Flush
        slot_src = do
            what <- lift . atomically $ foldr1 orElse
                [Slotted.pull slots >>= \x -> do
                    x <- case x of
                            Left wrapped -> do
                                writeTVar nesting 1
                                writeTVar lastStanza (Just wrapped)
                                return $ stanzaChan wrapped
                            Right x      -> do
                                when (isEventBeginElement x)
                                    $ modifyTVar' nesting (+1)
                                when (isEventEndElement x) $ do
                                    n <- readTVar nesting
                                    when (n==1) $ writeTVar lastStanza Nothing
                                    modifyTVar' nesting (subtract 1)
                                return x
                    writeTVar needsFlush True
                    return $ do
                    -- liftIO $ wlog $ "yielding Chunk: " ++ show x
                    yield (Chunk x)
                    slot_src
                ,do Slotted.isEmpty slots >>= check
                    readTVar needsFlush >>= check
                    writeTVar needsFlush False
                    return $ do
                    -- liftIO $ wlog "yielding Flush"
                    yield Flush
                    slot_src
                ,readTMVar rdone >> return (return ())
                ]
            what
    forkIO $ do (greet_src >> slot_src) $$ snk
                last <- atomically $ readTVar lastStanza
                es <- while (atomically . fmap not $ Slotted.isEmpty slots)
                            (atomically . Slotted.pull $ slots)
                let es' = mapMaybe metadata es
                    metadata (Left s) = Just s
                    metadata _        = Nothing
                let fail s = wlog $ "failed delivery: " ++ show (stanzaId s)
                maybe (return ()) fail last
                mapM_ fail es' -- TODO: queue or save these for re-connect?
                wlog $ "end post-queue fork: " ++ show k
    output <- atomically newTChan
    forkIO $ do
        -- mapM_ (atomically . Slotted.push slots Nothing) greetPeer
        fix $ \loop -> do
            what <- atomically $ foldr1 orElse
                [readTChan output >>= \stanza -> return $ do
#ifndef PINGNOISE
                    let notping f = case stanzaType stanza of Pong -> return ()
                                                              _ -> f
#else
                    let notping f = f
#endif
                    notping $ do
                        dup <- atomically $ cloneStanza stanza
                        let typ = Strict8.pack $ c ++ "<-"++(concat . take 1 . words $ show (stanzaType dup))++" "
                            c = case k of
                                    ClientKey {} -> "C"
                                    PeerKey {}   -> "P"
                        wlog ""
                        stanzaToConduit dup $$ prettyPrint typ
                    stanzaToConduit stanza =$= wrapStanzaConduit stanza
                        $$ awaitForever
                            $ liftIO . atomically . Slotted.push slots Nothing
                    loop
                ,do pingflag >>= check
                    return $ do
                    to <- xmppTellPeerHisName xmpp k -- addrToText (callBackAddress k)
                    let from = me -- Look it up from Server object
                                  -- or pass it with Connection event.
                        mid = Just "ping"
                        ping = makePing namespace mid to from
                    ping <- atomically $ wrapStanzaList ping
                    mapM_ (atomically . Slotted.push slots (Just $ PingSlot))
                          ping
#ifdef PINGNOISE
                    wlog ""
                    CL.sourceList ping $$ prettyPrint $ case k of
                        ClientKey {} -> "C<-Ping"
                        PeerKey {} -> "P<-Ping "
#endif
                    loop
                ,readTMVar rdone >> return (return ())
                ]
            what
        wlog $ "end pre-queue fork: " ++ show k
    forkIO $ do
        -- src $$ awaitForever (lift . putStrLn . takeWhile (/=' ') . show)
        src $$ xmppInbound sv xmpp k laddr pingflag src stanzas output rdone
        atomically $ putTMVar rdone ()
        wlog $ "end reader fork: " ++ show k
    return output

{-
data Peer = Peer
    { peerWanted :: TVar Bool -- ^ False when this peer is on a you-call-me basis
    , peerState :: TVar PeerState
    }
data PeerState
    = PeerPendingConnect UTCTime
    | PeerPendingAccept UTCTime
    | PeerConnected (TChan Stanza)
-}

peerKey :: (Socket,SockAddr) -> IO (ConnectionKey,SockAddr)
peerKey (sock,addr) = do
    peer <- 
      sIsConnected sock >>= \c -> 
        if c then getPeerName sock -- addr is normally socketName
             else return addr      -- Weird hack: addr is would-be peer name
    laddr <- getSocketName sock
    return $ (PeerKey (peer `withPort` fromIntegral peerport),laddr)

clientKey :: (Socket,SockAddr) -> IO (ConnectionKey,SockAddr)
clientKey (sock,addr) = do
    paddr <- getPeerName sock
    return $ (ClientKey addr,paddr)

xmlifyRosterItems :: Monad m => Set Text -> Text -> Set Text -> ConduitM i Event m ()
xmlifyRosterItems solicited stype set = mapM_ item (Set.toList set) 
 where
  item jid = do yield $ EventBeginElement "{jabber:iq:roster}item" 
                        ([ attr "jid" jid
                         , attr "subscription" stype
                         ]++if Set.member jid solicited 
                             then [attr "ask" "subscribe"]
                             else [] )
                yield $ EventEndElement "{jabber:iq:roster}item"

sendRoster ::
    StanzaWrap a
    -> XMPPServerParameters
    -> TChan (StanzaWrap (TChan Event))
    -> IO ()
sendRoster query xmpp replyto = do
    let k = case stanzaOrigin query of
             NetworkOrigin k _ -> Just k
             LocalPeer -> Nothing -- local peer requested roster?
    flip (maybe $ return ()) k $ \k -> do
    jid <- case k of
                ClientKey {} -> xmppTellClientHisName xmpp k -- LookupClientJID xmpp k
                PeerKey {}   -> xmppTellClientNameOfPeer xmpp k
    let getlist f = do
            bs <- f xmpp k
            -- js <- mapM parseHostNameJID bs
            return (Set.fromList bs) -- js)
    buddies     <- getlist xmppRosterBuddies
    subscribers <- getlist xmppRosterSubscribers
    solicited   <- getlist xmppRosterSolicited
    subnone0    <- getlist xmppRosterOthers
    let subnone = subnone0 \\ (Set.union buddies subscribers)
    let subto = buddies \\ subscribers
    let subfrom = subscribers \\ buddies
    let subboth = Set.intersection buddies subscribers
    let roster = do
            yield $ EventBeginElement "{jabber:client}iq"
                        (consid (stanzaId query)
                            [ attr "to" jid
                            , attr "type" "result" ])
            yield $ EventBeginElement "{jabber:iq:roster}query" [] -- todo: ver? 
            xmlifyRosterItems solicited "to" subto
            xmlifyRosterItems solicited "from" subfrom
            xmlifyRosterItems solicited "both" subboth
            xmlifyRosterItems solicited "none" subnone
            yield $ EventEndElement "{jabber:iq:roster}query"
            yield $ EventEndElement "{jabber:client}iq"
    (chan,clsrs,quitvar) <- conduitToChan roster
    ioWriteChan replyto
        Stanza  { stanzaType = Roster
                , stanzaId = (stanzaId query)
                , stanzaTo = Just jid
                , stanzaFrom = Nothing
                , stanzaChan = chan
                , stanzaClosers = clsrs
                , stanzaInterrupt = quitvar
                , stanzaOrigin = LocalPeer
                }

socketFromKey :: Server ConnectionKey SockAddr -> ConnectionKey -> IO SockAddr
socketFromKey sv k = do
    map <- atomically $ readTVar (conmap sv)
    let mcd = Map.lookup k map
    case mcd of
        Nothing -> case k of
                    ClientKey addr -> return addr
                    PeerKey addr -> return addr 
                        -- XXX: ? wrong address
                        -- Shouldnt happen anyway.
        Just cd -> return $ cdata cd

monitor ::
    Server ConnectionKey SockAddr
    -> ConnectionParameters ConnectionKey SockAddr
    -> XMPPServerParameters
    -> IO b
monitor sv params xmpp = do
    chan <- return $ serverEvent sv
    stanzas <- atomically newTChan
    quitVar <- atomically newEmptyTMVar
    fix $ \loop -> do
    action <- atomically $ foldr1 orElse
      [ readTChan chan >>= \((k,u),e) -> return $ do 
        case e of
            Connection pingflag conread conwrite -> do
                 wlog $ tomsg k "Connection"
                 let (xsrc,xsnk) = xmlStream conread conwrite
                 outs <- forkConnection sv xmpp k u pingflag xsrc xsnk stanzas
                 xmppNewConnection xmpp k u outs
                 return ()
            ConnectFailure addr -> return () -- wlog $ tomsg k "ConnectFailure"
            EOF        -> do wlog $ tomsg k "EOF"
                             xmppEOF xmpp k
            HalfConnection In -> do
                wlog $ tomsg k "ReadOnly"
                control sv (Connect (callBackAddress k) params)
            HalfConnection Out -> wlog $ tomsg k "WriteOnly"
            RequiresPing -> return () -- wlog $ tomsg k "RequiresPing"
            _ -> return ()
      , readTChan stanzas >>= \stanza -> return $ do
        dup <- case stanzaType stanza of
                Message {} -> do
                    dup <- atomically $ cloneStanza stanza -- dupped so we can make debug print
                    return dup
                _ -> return stanza
        forkIO $ do
            case stanzaType stanza of
                Message {} -> do
                    let fail = wlog $ "Failed delivery id="++show (stanzaId stanza) -- TODO
                    xmppDeliverMessage xmpp fail stanza
                _ -> return ()
            case stanzaOrigin stanza of
                NetworkOrigin k@(ClientKey {}) replyto -> 
                    case stanzaType stanza of
                        RequestResource wanted -> do
                            sockaddr <- socketFromKey sv k
                            rsc <- xmppChooseResourceName xmpp k sockaddr wanted
                            let reply = iq_bind_reply (stanzaId stanza) rsc
                            sendReply quitVar SetResource reply replyto
                        SessionRequest -> do
                            me <- xmppTellMyNameToClient xmpp
                            let reply = iq_session_reply (stanzaId stanza) me
                            sendReply quitVar Pong reply replyto
                        RequestRoster -> do
                            sendRoster stanza xmpp replyto
                            xmppSubscribeToRoster xmpp k
                        PresenceStatus {} -> do
                            xmppInformClientPresence xmpp k stanza
                        UnrecognizedQuery query -> do
                            me <- xmppTellMyNameToClient xmpp
                            let reply = iq_service_unavailable (stanzaId stanza) me query
                            sendReply quitVar Error reply replyto
                        _ -> return ()
                _ -> return ()
        -- We need to clone in the case the stanza is passed on as for Message.
#ifndef PINGNOISE
        let notping f = case stanzaType stanza of Pong -> return ()
                                                  _ -> f
        notping $ do
#endif
        let typ = Strict8.pack $ c ++ "->"++(concat . take 1 . words $ show (stanzaType stanza))++" "
            c = case stanzaOrigin stanza of
                    LocalPeer -> "*"
                    NetworkOrigin (ClientKey {}) _ -> "C"
                    NetworkOrigin (PeerKey {})   _ -> "P"
        wlog ""
        stanzaToConduit dup $$ prettyPrint typ
        
      ]
    action
    loop
 where
    tomsg k str =  printf "%12s %s" str (show k)
        where
            _ = str :: String

data XMPPServer
    = XMPPServer { _xmpp_sv :: Server ConnectionKey SockAddr
                 , _xmpp_peer_params :: ConnectionParameters ConnectionKey SockAddr
                 }

addPeer :: XMPPServer -> SockAddr -> IO ()
addPeer sv addr = do
    control (_xmpp_sv sv) (ConnectWithEndlessRetry addr (_xmpp_peer_params sv) 10000)

xmppServer :: ( MonadResource m
              , MonadIO m
              ) => XMPPServerParameters -> m XMPPServer
xmppServer xmpp = do
    sv <- server
    -- some fuzz helps avoid simultaneity
    pingfuzz <- liftIO $ do
        gen <- System.Random.getStdGen
        let (r,gen') = System.Random.next gen
        return $ r `mod` 2000 -- maximum 2 seconds of fuzz
    liftIO . wlog $ "pingfuzz = " ++ show pingfuzz
    let peer_params = (connectionDefaults peerKey)
                          { pingInterval = 15000 + pingfuzz
                          , timeout = 2000
                          , duplex = False }
        client_params = (connectionDefaults clientKey)
                          { pingInterval = 0
                          , timeout = 0
                          }
    liftIO $ do
        forkIO $ monitor sv peer_params xmpp
        control sv (Listen peerport peer_params)
        control sv (Listen clientport client_params)
    return XMPPServer { _xmpp_sv = sv, _xmpp_peer_params = peer_params }

#if MIN_VERSION_stm(2,4,0)
#else
-- |Clone a 'TChan': similar to dupTChan, but the cloned channel starts with the
-- same content available as the original channel.
--
-- Terrible inefficient implementation provided to build against older libraries.
cloneTChan :: TChan a -> STM (TChan a)
cloneTChan chan = do
    contents <- chanContents' chan
    chan2 <- dupTChan chan
    mapM_ (writeTChan chan) contents
    return chan2
 where
    chanContents' chan = do
        b <- isEmptyTChan chan
        if b then return [] else do
        x <- readTChan chan
        xs <- chanContents' chan
        return (x:xs)
#endif