root / src / Ganeti / UDSServer.hs @ 5e671e0e
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{-# LANGUAGE TemplateHaskell #-} |
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{-| Implementation of the Ganeti Unix Domain Socket JSON server interface. |
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-} |
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{- |
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Copyright (C) 2013 Google Inc. |
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2 of the License, or |
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(at your option) any later version. |
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|
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This program is distributed in the hope that it will be useful, but |
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WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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General Public License for more details. |
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|
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software |
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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02110-1301, USA. |
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-} |
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module Ganeti.UDSServer |
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( ConnectConfig(..) |
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, Client |
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, Server |
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, RecvResult(..) |
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, MsgKeys(..) |
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, strOfKey |
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, connectClient |
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, connectServer |
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, acceptClient |
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, closeClient |
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, closeServer |
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, buildResponse |
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, recvMsg |
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, recvMsgExt |
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, sendMsg |
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) where |
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|
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import Control.Exception (catch) |
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import Data.IORef |
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import qualified Data.ByteString as B |
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import qualified Data.ByteString.Lazy as BL |
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import qualified Data.ByteString.UTF8 as UTF8 |
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import qualified Data.ByteString.Lazy.UTF8 as UTF8L |
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import Data.Word (Word8) |
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import Control.Monad |
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import qualified Network.Socket as S |
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import System.Directory (removeFile) |
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import System.IO (hClose, hFlush, hWaitForInput, Handle, IOMode(..)) |
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import System.IO.Error (isEOFError) |
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import System.Timeout |
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import Text.JSON (encodeStrict) |
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import Text.JSON.Types |
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import Ganeti.Runtime (GanetiDaemon(..), MiscGroup(..), GanetiGroup(..)) |
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import Ganeti.THH |
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import Ganeti.Utils |
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-- * Utility functions |
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|
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-- | Wrapper over System.Timeout.timeout that fails in the IO monad. |
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withTimeout :: Int -> String -> IO a -> IO a |
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withTimeout secs descr action = do |
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result <- timeout (secs * 1000000) action |
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case result of |
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Nothing -> fail $ "Timeout in " ++ descr |
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Just v -> return v |
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-- * Generic protocol functionality |
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-- | Result of receiving a message from the socket. |
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data RecvResult = RecvConnClosed -- ^ Connection closed |
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| RecvError String -- ^ Any other error |
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| RecvOk String -- ^ Successfull receive |
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deriving (Show, Eq) |
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-- | The end-of-message separator. |
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eOM :: Word8 |
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eOM = 3 |
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-- | The end-of-message encoded as a ByteString. |
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bEOM :: B.ByteString |
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bEOM = B.singleton eOM |
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-- | Valid keys in the requests and responses. |
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data MsgKeys = Method |
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| Args |
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| Success |
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| Result |
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-- | The serialisation of MsgKeys into strings in messages. |
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$(genStrOfKey ''MsgKeys "strOfKey") |
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data ConnectConfig = ConnectConfig |
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{ connDaemon :: GanetiDaemon |
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, recvTmo :: Int |
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, sendTmo :: Int |
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} |
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-- | A client encapsulation. |
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data Client = Client { socket :: Handle -- ^ The socket of the client |
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, rbuf :: IORef B.ByteString -- ^ Already received buffer |
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, clientConfig :: ConnectConfig |
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} |
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-- | A server encapsulation. |
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data Server = Server { sSocket :: S.Socket -- ^ The bound server socket |
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, sPath :: FilePath -- ^ The scoket's path |
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, serverConfig :: ConnectConfig |
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} |
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-- | Connects to the master daemon and returns a Client. |
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connectClient |
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:: ConnectConfig -- ^ configuration for the client |
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-> Int -- ^ connection timeout |
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-> FilePath -- ^ socket path |
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-> IO Client |
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connectClient conf tmo path = do |
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s <- S.socket S.AF_UNIX S.Stream S.defaultProtocol |
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withTimeout tmo "creating a connection" $ |
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S.connect s (S.SockAddrUnix path) |
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rf <- newIORef B.empty |
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h <- S.socketToHandle s ReadWriteMode |
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return Client { socket=h, rbuf=rf, clientConfig=conf } |
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-- | Creates and returns a server endpoint. |
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connectServer :: ConnectConfig -> Bool -> FilePath -> IO Server |
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connectServer conf setOwner path = do |
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s <- S.socket S.AF_UNIX S.Stream S.defaultProtocol |
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S.bindSocket s (S.SockAddrUnix path) |
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when setOwner . setOwnerAndGroupFromNames path (connDaemon conf) $ |
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ExtraGroup DaemonsGroup |
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S.listen s 5 -- 5 is the max backlog |
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return Server { sSocket=s, sPath=path, serverConfig=conf } |
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-- | Closes a server endpoint. |
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-- FIXME: this should be encapsulated into a nicer type. |
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closeServer :: Server -> IO () |
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closeServer server = do |
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S.sClose (sSocket server) |
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removeFile (sPath server) |
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-- | Accepts a client |
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acceptClient :: Server -> IO Client |
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acceptClient s = do |
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-- second return is the address of the client, which we ignore here |
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(client_socket, _) <- S.accept (sSocket s) |
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new_buffer <- newIORef B.empty |
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handle <- S.socketToHandle client_socket ReadWriteMode |
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return Client { socket=handle |
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, rbuf=new_buffer |
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, clientConfig=serverConfig s |
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} |
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-- | Closes the client socket. |
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closeClient :: Client -> IO () |
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closeClient = hClose . socket |
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-- | Sends a message over a transport. |
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sendMsg :: Client -> String -> IO () |
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sendMsg s buf = withTimeout (sendTmo $ clientConfig s) "sending a message" $ do |
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let encoded = UTF8L.fromString buf |
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handle = socket s |
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BL.hPut handle encoded |
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B.hPut handle bEOM |
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hFlush handle |
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-- | Given a current buffer and the handle, it will read from the |
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-- network until we get a full message, and it will return that |
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-- message and the leftover buffer contents. |
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recvUpdate :: ConnectConfig -> Handle -> B.ByteString |
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-> IO (B.ByteString, B.ByteString) |
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recvUpdate conf handle obuf = do |
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nbuf <- withTimeout (recvTmo conf) "reading a response" $ do |
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_ <- hWaitForInput handle (-1) |
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B.hGetNonBlocking handle 4096 |
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let (msg, remaining) = B.break (eOM ==) nbuf |
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newbuf = B.append obuf msg |
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if B.null remaining |
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then recvUpdate conf handle newbuf |
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else return (newbuf, B.tail remaining) |
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-- | Waits for a message over a transport. |
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recvMsg :: Client -> IO String |
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recvMsg s = do |
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cbuf <- readIORef $ rbuf s |
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let (imsg, ibuf) = B.break (eOM ==) cbuf |
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(msg, nbuf) <- |
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if B.null ibuf -- if old buffer didn't contain a full message |
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-- then we read from network: |
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then recvUpdate (clientConfig s) (socket s) cbuf |
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else return (imsg, B.tail ibuf) -- else we return data from our buffer |
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writeIORef (rbuf s) nbuf |
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return $ UTF8.toString msg |
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-- | Extended wrapper over recvMsg. |
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recvMsgExt :: Client -> IO RecvResult |
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recvMsgExt s = |
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Control.Exception.catch (liftM RecvOk (recvMsg s)) $ \e -> |
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return $ if isEOFError e |
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then RecvConnClosed |
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else RecvError (show e) |
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-- | Serialize the response to String. |
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buildResponse :: Bool -- ^ Success |
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-> JSValue -- ^ The arguments |
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-> String -- ^ The serialized form |
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buildResponse success args = |
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let ja = [ (strOfKey Success, JSBool success) |
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, (strOfKey Result, args)] |
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jo = toJSObject ja |
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in encodeStrict jo |