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|
-- |
-- Copyright : (c) Sam Truzjan 2013
-- License : BSD3
-- Maintainer : pxqr.sta@gmail.com
-- Stability : experimental
-- Portability : portable
--
-- This module provides straightforward implementation of KRPC
-- protocol. In many situations 'Network.KRPC' should be prefered
-- since it gives more safe, convenient and high level api.
--
-- See <http://www.bittorrent.org/beps/bep_0005.html#krpc-protocol>
--
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE TypeSynonymInstances #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE DeriveDataTypeable #-}
module Network.KRPC.Protocol
( -- * Error
KError(..)
, serverError
-- * Query
, KQuery(..)
, MethodName
-- * Response
, KResponse(..)
) where
import Control.Exception.Lifted as Lifted
import Data.BEncode as BE
import Data.BEncode.BDict as BE
import Data.ByteString as B
import Data.ByteString.Char8 as BC
import Data.Typeable
-- | Errors used to signal that some error occurred while processing a
-- procedure call. Error may be send only from server to client but
-- not in the opposite direction.
--
-- Errors are encoded as bencoded dictionary:
--
-- > { "y" : "e", "e" : [<error_code>, <human_readable_error_reason>] }
--
data KError
-- | Some error doesn't fit in any other category.
= GenericError { errorMessage :: !ByteString }
-- | Occur when server fail to process procedure call.
| ServerError { errorMessage :: !ByteString }
-- | Malformed packet, invalid arguments or bad token.
| ProtocolError { errorMessage :: !ByteString }
-- | Occur when client trying to call method server don't know.
| MethodUnknown { errorMessage :: !ByteString }
deriving (Show, Read, Eq, Ord, Typeable)
instance BEncode KError where
{-# SPECIALIZE instance BEncode KError #-}
{-# INLINE toBEncode #-}
toBEncode e = toDict $
"e" .=! (errorCode e, errorMessage e)
.: "y" .=! ("e" :: ByteString)
.: endDict
{-# INLINE fromBEncode #-}
fromBEncode be @ (BDict d)
| BE.lookup "y" d == Just (BString "e")
= (`fromDict` be) $ do
uncurry mkKError <$>! "e"
fromBEncode _ = decodingError "KError"
instance Exception KError
type ErrorCode = Int
errorCode :: KError -> ErrorCode
errorCode (GenericError _) = 201
errorCode (ServerError _) = 202
errorCode (ProtocolError _) = 203
errorCode (MethodUnknown _) = 204
{-# INLINE errorCode #-}
mkKError :: ErrorCode -> ByteString -> KError
mkKError 201 = GenericError
mkKError 202 = ServerError
mkKError 203 = ProtocolError
mkKError 204 = MethodUnknown
mkKError _ = GenericError
{-# INLINE mkKError #-}
serverError :: SomeException -> KError
serverError = ServerError . BC.pack . show
type MethodName = ByteString
-- | Query used to signal that caller want to make procedure call to
-- callee and pass arguments in. Therefore query may be only sent from
-- client to server but not in the opposite direction.
--
-- Queries are encoded as bencoded dictionary:
--
-- > { "y" : "q", "q" : "<method_name>", "a" : [<arg1>, <arg2>, ...] }
--
data KQuery = KQuery
{ queryMethod :: !MethodName
, queryArgs :: !BValue
} deriving (Show, Read, Eq, Ord, Typeable)
instance BEncode KQuery where
{-# SPECIALIZE instance BEncode KQuery #-}
{-# INLINE toBEncode #-}
toBEncode (KQuery m args) = toDict $
"a" .=! args
.: "q" .=! m
.: "y" .=! ("q" :: ByteString)
.: endDict
{-# INLINE fromBEncode #-}
fromBEncode bv @ (BDict d)
| BE.lookup "y" d == Just (BString "q") = (`fromDict` bv) $ do
a <- field (req "a")
q <- field (req "q")
return $! KQuery q a
fromBEncode _ = decodingError "KQuery"
-- | KResponse used to signal that callee successufully process a
-- procedure call and to return values from procedure. KResponse should
-- not be sent if error occurred during RPC. Thus KResponse may be only
-- sent from server to client.
--
-- Responses are encoded as bencoded dictionary:
--
-- > { "y" : "r", "r" : [<val1>, <val2>, ...] }
--
newtype KResponse = KResponse
{ respVals :: BValue
} deriving (Show, Read, Eq, Ord, Typeable)
instance BEncode KResponse where
{-# INLINE toBEncode #-}
toBEncode (KResponse vals) = toDict $
"r" .=! vals
.: "y" .=! ("r" :: ByteString)
.: endDict
{-# INLINE fromBEncode #-}
fromBEncode bv @ (BDict d)
| BE.lookup "y" d == Just (BString "r") = (`fromDict` bv) $ do
KResponse <$>! "r"
fromBEncode _ = decodingError "KDict"
|
