summaryrefslogtreecommitdiff
path: root/src/Network/KRPC/Manager.hs
blob: 4852eb3824676fe6ec35755c4dcaad00368dd83b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
-- |
--   Copyright   :  (c) Sam Truzjan 2013, 2014
--   License     :  BSD3
--   Maintainer  :  pxqr.sta@gmail.com
--   Stability   :  experimental
--   Portability :  portable
--
--   Normally, you don't need to import this module.
--
{-# LANGUAGE OverloadedStrings      #-}
{-# LANGUAGE FlexibleInstances      #-}
{-# LANGUAGE FlexibleContexts       #-}
{-# LANGUAGE ScopedTypeVariables    #-}
{-# LANGUAGE DefaultSignatures      #-}
{-# LANGUAGE MultiParamTypeClasses  #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE DeriveDataTypeable     #-}
{-# LANGUAGE TemplateHaskell        #-}
module Network.KRPC.Manager
       ( -- * Manager
         MonadKRPC (..)
       , Options (..)
       , Manager
       , newManager
       , closeManager
       , withManager
       , isActive
       , listen

         -- * Queries
       , QueryFailure (..)
       , query
       , query'
       , queryRaw
       , getQueryCount

         -- * Handlers
       , HandlerFailure (..)
       , Handler
       , handler
       ) where

import Control.Applicative
import Control.Concurrent
import Control.Concurrent.Lifted (fork)
import Control.Exception hiding (Handler)
import qualified Control.Exception.Lifted as E (Handler (..))
import Control.Exception.Lifted as Lifted (catches, finally)
import Control.Monad
import Control.Monad.Logger
import Control.Monad.Reader
import Control.Monad.Trans.Control
import Data.BEncode as BE
import Data.BEncode.Internal as BE
import Data.BEncode.Pretty (showBEncode)
import qualified Data.ByteString.Base16 as Base16
import Data.ByteString as BS
import Data.ByteString.Char8 as BC
import Data.ByteString.Lazy as BL
import Data.Default.Class
import Data.IORef
import Data.List as L
import Data.Map as M
import Data.Monoid
import Data.Text as T
import Data.Text.Encoding as T
import Data.Tuple
import Data.Typeable
import Network.KRPC.Message
import Network.KRPC.Method
import Network.Socket hiding (listen)
import Network.Socket.ByteString as BS
import System.IO.Error
import System.Timeout


{-----------------------------------------------------------------------
--  Options
-----------------------------------------------------------------------}

-- | RPC manager options.
data Options = Options
  { -- | Initial 'TransactionId' incremented with each 'query';
    optSeedTransaction :: {-# UNPACK #-} !Int

    -- | Time to wait for response from remote node, in seconds.
  , optQueryTimeout    :: {-# UNPACK #-} !Int

    -- | Maximum number of bytes to receive.
  , optMaxMsgSize      :: {-# UNPACK #-} !Int
  } deriving (Show, Eq)

defaultSeedTransaction :: Int
defaultSeedTransaction = 0

defaultQueryTimeout :: Int
defaultQueryTimeout = 120

defaultMaxMsgSize :: Int
defaultMaxMsgSize = 64 * 1024

-- | Permissive defaults.
instance Default Options where
  def = Options
    { optSeedTransaction = defaultSeedTransaction
    , optQueryTimeout    = defaultQueryTimeout
    , optMaxMsgSize      = defaultMaxMsgSize
    }

validateOptions :: Options -> IO ()
validateOptions Options {..}
  | optQueryTimeout < 1
  = throwIO (userError "krpc: non-positive query timeout")
  | optMaxMsgSize   < 1
  = throwIO (userError "krpc: non-positive buffer size")
  |       otherwise     = return ()

{-----------------------------------------------------------------------
--  Options
-----------------------------------------------------------------------}

type KResult = Either KError KResponse

type TransactionCounter = IORef Int
type CallId             = (TransactionId, SockAddr)
type CallRes            = MVar (BValue, KResult)
type PendingCalls       = IORef (Map CallId CallRes)

type HandlerBody h = SockAddr -> BValue -> h (BE.Result BValue)

-- | Handler is a function which will be invoked then some /remote/
-- node querying /this/ node.
type Handler     h = (MethodName, HandlerBody h)

-- | Keep track pending queries made by /this/ node and handle queries
-- made by /remote/ nodes.
data Manager h = Manager
  { sock               :: !Socket
  , options            :: !Options
  , listenerThread     :: !(MVar ThreadId)
  , transactionCounter :: {-# UNPACK #-} !TransactionCounter
  , pendingCalls       :: {-# UNPACK #-} !PendingCalls
  , handlers           :: [Handler h]
  }

-- | A monad which can perform or handle queries.
class (MonadBaseControl IO m, MonadLogger m, MonadIO m)
    => MonadKRPC h m | m -> h where

  -- | Ask for manager.
  getManager :: m (Manager h)

  default getManager :: MonadReader (Manager h) m => m (Manager h)
  getManager = ask

  -- | Can be used to add logging for instance.
  liftHandler :: h a -> m a

  default liftHandler :: m a -> m a
  liftHandler = id

instance (MonadBaseControl IO h, MonadLogger h, MonadIO h)
      => MonadKRPC h (ReaderT (Manager h) h) where

  liftHandler = lift

sockAddrFamily :: SockAddr -> Family
sockAddrFamily (SockAddrInet  _ _    ) = AF_INET
sockAddrFamily (SockAddrInet6 _ _ _ _) = AF_INET6
sockAddrFamily (SockAddrUnix  _      ) = AF_UNIX
sockAddrFamily (SockAddrCan _        ) = AF_CAN

-- | Bind socket to the specified address. To enable query handling
-- run 'listen'.
newManager :: Options        -- ^ various protocol options;
           -> SockAddr       -- ^ address to listen on;
           -> [Handler h]    -- ^ handlers to run on incoming queries.
           -> IO (Manager h) -- ^ new rpc manager.
newManager opts @ Options {..} servAddr handlers = do
    validateOptions opts
    sock  <- bindServ
    tref  <- newEmptyMVar
    tran  <- newIORef optSeedTransaction
    calls <- newIORef M.empty
    return $ Manager sock opts tref tran calls handlers
  where
    bindServ = do
      let family = sockAddrFamily servAddr
      sock <- socket family Datagram defaultProtocol
      when (family == AF_INET6) $ do
        setSocketOption sock IPv6Only 0
      bindSocket sock servAddr
      return sock

-- | Unblock all pending calls and close socket.
closeManager :: Manager m -> IO ()
closeManager Manager {..} = do
  maybe (return ()) killThread =<< tryTakeMVar listenerThread
  -- TODO unblock calls
  close sock

-- | Check if the manager is still active. Manager becomes active
-- until 'closeManager' called.
isActive :: Manager m -> IO Bool
isActive Manager {..} = liftIO $ isBound sock
{-# INLINE isActive #-}

-- | Normally you should use Control.Monad.Trans.Resource.allocate
-- function.
withManager :: Options -> SockAddr -> [Handler h]
            -> (Manager h -> IO a) -> IO a
withManager opts addr hs = bracket (newManager opts addr hs) closeManager

{-----------------------------------------------------------------------
--  Logging
-----------------------------------------------------------------------}

-- TODO prettify log messages
querySignature :: MethodName -> TransactionId -> SockAddr -> Text
querySignature name transaction addr = T.concat
  [  "&", T.decodeUtf8 name
  , " #", T.decodeUtf8 (Base16.encode transaction) -- T.decodeUtf8 transaction
  , " @", T.pack (show addr)
  ]

{-----------------------------------------------------------------------
--  Client
-----------------------------------------------------------------------}
-- we don't need to know about TransactionId while performing query,
-- so we introduce QueryFailure exceptions

-- | Used to signal 'query' errors.
data QueryFailure
  = SendFailed                  -- ^ unable to send query;
  | QueryFailed  ErrorCode Text -- ^ remote node return error;
  | TimeoutExpired              -- ^ remote node not responding.
  deriving (Show, Eq, Typeable)

instance Exception QueryFailure

sendMessage :: MonadIO m => BEncode a => Socket -> SockAddr -> a -> m ()
sendMessage sock addr a = do
  liftIO $ sendManyTo sock (BL.toChunks (BE.encode a)) addr

genTransactionId :: TransactionCounter -> IO TransactionId
genTransactionId ref = do
  cur <- atomicModifyIORef' ref $ \ cur -> (succ cur, cur)
  return $ BC.pack (show cur)

-- | How many times 'query' call have been performed.
getQueryCount :: MonadKRPC h m => m Int
getQueryCount = do
  Manager {..} <- getManager
  curTrans <- liftIO $ readIORef transactionCounter
  return $ curTrans - optSeedTransaction options

registerQuery :: CallId -> PendingCalls -> IO CallRes
registerQuery cid ref = do
  ares <- newEmptyMVar
  atomicModifyIORef' ref $ \ m -> (M.insert cid ares m, ())
  return ares

-- simultaneous M.lookup and M.delete guarantees that we never get two
-- or more responses to the same query
unregisterQuery :: CallId -> PendingCalls -> IO (Maybe CallRes)
unregisterQuery cid ref = do
  atomicModifyIORef' ref $ swap .
    M.updateLookupWithKey (const (const Nothing)) cid


-- (sendmsg EINVAL)
sendQuery :: BEncode a => Socket -> SockAddr -> a -> IO ()
sendQuery sock addr q = handle sockError $ sendMessage sock addr q
  where
    sockError :: IOError -> IO ()
    sockError _ = throwIO SendFailed

-- | Enqueue query to the given node.
--
--  This function should throw 'QueryFailure' exception if quered node
--  respond with @error@ message or the query timeout expires.
--
query :: forall h m a b. (MonadKRPC h m, KRPC a b) => SockAddr -> a -> m b
query addr params = queryK addr params (\_ x _ -> x)

-- | Like 'query' but possibly returns your externally routable IP address.
query' :: forall h m a b. (MonadKRPC h m, KRPC a b) => SockAddr -> a -> m (b, Maybe ReflectedIP)
query' addr params = queryK addr params (const (,))

-- | Enqueue a query, but give us the complete BEncoded content sent by the
-- remote Node.  This is useful for handling extensions that this library does
-- not otherwise support.
queryRaw :: forall h m a b. (MonadKRPC h m, KRPC a b) => SockAddr -> a -> m (b, BValue)
queryRaw addr params = queryK addr params (\raw x _ -> (x,raw))

queryK :: forall h m a b x. (MonadKRPC h m, KRPC a b) =>
    SockAddr -> a -> (BValue -> b -> Maybe ReflectedIP -> x) -> m x
queryK addr params kont = do
  Manager {..} <- getManager
  tid <- liftIO $ genTransactionId transactionCounter
  let queryMethod = method :: Method a b
  let signature = querySignature (methodName queryMethod) tid addr
  $(logDebugS) "query.sending" signature

  mres <- liftIO $ do
    ares <- registerQuery (tid, addr) pendingCalls

    let q = KQuery (toBEncode params) (methodName queryMethod) tid
    sendQuery sock addr q
      `onException` unregisterQuery (tid, addr) pendingCalls

    timeout (optQueryTimeout options * 10 ^ (6 :: Int)) $ do
      (raw,res) <- readMVar ares
      case res of
        Left  (KError   c m _) -> throwIO $ QueryFailed c (T.decodeUtf8 m)
        Right (KResponse {..}) ->
          case fromBEncode respVals of
            Right r -> pure $ kont raw r respIP
            Left  e -> throwIO $ QueryFailed ProtocolError (T.pack e)

  case mres of
    Just res -> do
      $(logDebugS) "query.responded" $ signature
      return res

    Nothing -> do
      _ <- liftIO $ unregisterQuery (tid, addr) pendingCalls
      $(logWarnS) "query.not_responding" $ signature <> " for " <>
             T.pack (show (optQueryTimeout options)) <> " seconds"
      throw $ TimeoutExpired

{-----------------------------------------------------------------------
--  Handlers
-----------------------------------------------------------------------}
-- we already throw:
--
--   * ErrorCode(MethodUnknown) in the 'dispatchHandler';
--
--   * ErrorCode(ServerError) in the 'runHandler';
--
--   * ErrorCode(GenericError) in the 'runHandler' (those can be
--   async exception too)
--
--  so HandlerFailure should cover *only* 'ProtocolError's.

-- | Used to signal protocol errors.
data HandlerFailure
  = BadAddress            -- ^ for e.g.: node calls herself;
  | InvalidParameter Text -- ^ for e.g.: bad session token.
    deriving (Show, Eq, Typeable)

instance Exception HandlerFailure

prettyHF :: HandlerFailure -> BS.ByteString
prettyHF  BadAddress               = T.encodeUtf8 "bad address"
prettyHF (InvalidParameter reason) = T.encodeUtf8 $
  "invalid parameter: " <> reason

prettyQF :: QueryFailure -> BS.ByteString
prettyQF e = T.encodeUtf8 $ "handler fail while performing query: "
  <> T.pack (show e)

-- | Make handler from handler function. Any thrown exception will be
-- supressed and send over the wire back to the querying node.
--
--   If the handler make some 'query' normally it /should/ handle
--   corresponding 'QueryFailure's.
--
handler :: forall h a b. (KRPC a b, Monad h)
        => (SockAddr -> a -> h b) -> Handler h
handler body = (name, wrapper)
  where
    Method name = method :: Method a b
    wrapper addr args =
      case fromBEncode args of
        Left  e -> return $ Left e
        Right a -> do
          r <- body addr a
          return $ Right $ toBEncode r

runHandler :: MonadKRPC h m
           => HandlerBody h -> SockAddr -> KQuery -> m KResult
runHandler h addr KQuery {..} = Lifted.catches wrapper failbacks
  where
    signature = querySignature queryMethod queryId addr

    wrapper = do
      $(logDebugS) "handler.quered" signature
      result <- liftHandler (h addr queryArgs)

      case result of
        Left msg -> do
          $(logDebugS) "handler.bad_query" $ signature <> " !" <> T.pack msg
          return $ Left $ KError ProtocolError (BC.pack msg) queryId

        Right a -> do
          $(logDebugS) "handler.success" signature
          return $ Right $ KResponse a queryId (Just $ ReflectedIP addr)

    failbacks =
      [ E.Handler $ \ (e :: HandlerFailure) -> do
          $(logDebugS) "handler.failed" signature
          return $ Left $ KError ProtocolError (prettyHF e) queryId

        -- may happen if handler makes query and fail
      , E.Handler $ \ (e :: QueryFailure) -> do
          return $ Left $ KError ServerError (prettyQF e) queryId

        -- since handler thread exit after sendMessage we can safely
        -- suppress async exception here
      , E.Handler $ \ (e :: SomeException) -> do
          return $ Left $ KError GenericError (BC.pack (show e)) queryId
      ]

dispatchHandler :: MonadKRPC h m => KQuery -> SockAddr -> m KResult
dispatchHandler q @ KQuery {..} addr = do
  Manager {..} <- getManager
  case L.lookup queryMethod handlers of
    Nothing -> return $ Left $ KError MethodUnknown queryMethod queryId
    Just h  -> runHandler h addr q

{-----------------------------------------------------------------------
--  Listener
-----------------------------------------------------------------------}

-- TODO bound amount of parallel handler *threads*:
--
-- peer A flooding with find_node
-- peer B trying to ping peer C
-- peer B fork too many threads
-- ... space leak
--
handleQuery :: MonadKRPC h m => BValue -> KQuery -> SockAddr -> m ()
handleQuery raw q addr = void $ fork $ do
  Manager {..} <- getManager
  res <- dispatchHandler q addr
  let resbe = either toBEncode toBEncode res
  $(logOther "q") $ T.unlines
    [ either (const "<unicode-fail>") id $ T.decodeUtf8' (BL.toStrict $ showBEncode raw)
    , "==>"
    , either (const "<unicode-fail>") id $ T.decodeUtf8' (BL.toStrict $ showBEncode resbe)
    ]
  sendMessage sock addr resbe

handleResponse :: MonadKRPC h m => BValue -> KResult -> SockAddr -> m ()
handleResponse raw result addr = do
  Manager {..} <- getManager
  liftIO $ do
    let resultId = either errorId respId  result
    mcall <- unregisterQuery (resultId, addr) pendingCalls
    case mcall of
      Nothing   -> return ()
      Just ares -> putMVar ares (raw,result)

handleMessage :: MonadKRPC h m => BValue -> KMessage -> SockAddr -> m ()
handleMessage raw (Q q) = handleQuery    raw q
handleMessage raw (R r) = handleResponse raw (Right r)
handleMessage raw (E e) = handleResponse raw (Left  e)

listener :: MonadKRPC h m => m ()
listener = do
  Manager {..} <- getManager
  forever $ do
    (bs, addr) <- liftIO $ do
      handle exceptions $ BS.recvFrom sock (optMaxMsgSize options)

    case BE.parse bs >>= \r -> (,) r <$> BE.decode bs of
      -- TODO ignore unknown messages at all?
      Left  e       -> liftIO $ sendMessage sock addr $ unknownMessage e
      Right (raw,m) -> handleMessage raw m addr
  where
    exceptions :: IOError -> IO (BS.ByteString, SockAddr)
    exceptions e
        -- packets with empty payload may trigger eof exception
      | isEOFError e = return  ("", SockAddrInet 0 0)
      |   otherwise  = throwIO e

-- | Should be run before any 'query', otherwise they will never
-- succeed.
listen :: MonadKRPC h m => m ()
listen = do
  Manager {..} <- getManager
  tid <- fork $ do
    listener `Lifted.finally`
      liftIO (takeMVar listenerThread)
  liftIO $ putMVar listenerThread tid