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
|
-- |
-- 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.Message
( -- * Transaction
TransactionId
, unknownTransaction
-- * Error
, ErrorCode (..)
, KError(..)
, serverError
, decodeError
, unknownMethod
, unknownMessage
-- * Query
, KQuery(..)
, MethodName
-- * Response
, KResponse(..)
-- * Message
, KMessage (..)
) where
import Control.Applicative
import Control.Exception.Lifted as Lifted
import Data.BEncode as BE
import Data.ByteString as B
import Data.ByteString.Char8 as BC
import Data.Typeable
-- | This transaction ID is generated by the querying node and is
-- echoed in the response, so responses may be correlated with
-- multiple queries to the same node. The transaction ID should be
-- encoded as a short string of binary numbers, typically 2 characters
-- are enough as they cover 2^16 outstanding queries.
type TransactionId = ByteString
unknownTransaction :: TransactionId
unknownTransaction = ""
{-----------------------------------------------------------------------
-- Error messages
-----------------------------------------------------------------------}
data ErrorCode
-- | Some error doesn't fit in any other category.
= GenericError
-- | Occur when server fail to process procedure call.
| ServerError
-- | Malformed packet, invalid arguments or bad token.
| ProtocolError
-- | Occur when client trying to call method server don't know.
| MethodUnknown
deriving (Show, Read, Eq, Ord, Bounded, Typeable)
instance Enum ErrorCode where
fromEnum GenericError = 201
fromEnum ServerError = 202
fromEnum ProtocolError = 203
fromEnum MethodUnknown = 204
{-# INLINE fromEnum #-}
toEnum 201 = GenericError
toEnum 202 = ServerError
toEnum 203 = ProtocolError
toEnum 204 = MethodUnknown
toEnum _ = GenericError
{-# INLINE toEnum #-}
instance BEncode ErrorCode where
toBEncode = toBEncode . fromEnum
{-# INLINE toBEncode #-}
fromBEncode b = toEnum <$> fromBEncode b
{-# INLINE fromBEncode #-}
-- | 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 = KError
{ errorCode :: !ErrorCode
, errorMessage :: !ByteString
, errorId :: !TransactionId
} deriving (Show, Read, Eq, Ord, Typeable)
instance BEncode KError where
toBEncode KError {..} = toDict $
"e" .=! (errorCode, errorMessage)
.: "t" .=! errorId
.: "y" .=! ("e" :: ByteString)
.: endDict
{-# INLINE toBEncode #-}
fromBEncode = fromDict $ do
lookAhead $ match "y" (BString "e")
(code, msg) <- field (req "e")
KError code msg <$>! "t"
{-# INLINE fromBEncode #-}
instance Exception KError
serverError :: SomeException -> TransactionId -> KError
serverError e = KError ServerError (BC.pack (show e))
decodeError :: String -> TransactionId -> KError
decodeError msg = KError ProtocolError (BC.pack msg)
unknownMethod :: MethodName -> TransactionId -> KError
unknownMethod = KError MethodUnknown
unknownMessage :: String -> KError
unknownMessage msg = KError ProtocolError (BC.pack msg) ""
{-----------------------------------------------------------------------
-- Query messages
-----------------------------------------------------------------------}
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
{ queryArgs :: !BValue
, queryMethod :: !MethodName
, queryId :: !TransactionId
} deriving (Show, Read, Eq, Ord, Typeable)
instance BEncode KQuery where
toBEncode KQuery {..} = toDict $
"a" .=! queryArgs
.: "q" .=! queryMethod
.: "t" .=! queryId
.: "y" .=! ("q" :: ByteString)
.: endDict
{-# INLINE toBEncode #-}
fromBEncode = fromDict $ do
lookAhead $ match "y" (BString "q")
KQuery <$>! "a" <*>! "q" <*>! "t"
{-# INLINE fromBEncode #-}
{-----------------------------------------------------------------------
-- Response messages
-----------------------------------------------------------------------}
-- | 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>, ...] }
--
data KResponse = KResponse
{ respVals :: BValue
, respId :: TransactionId
} deriving (Show, Read, Eq, Ord, Typeable)
instance BEncode KResponse where
toBEncode KResponse {..} = toDict $
"r" .=! respVals
.: "t" .=! respId
.: "y" .=! ("r" :: ByteString)
.: endDict
{-# INLINE toBEncode #-}
fromBEncode = fromDict $ do
lookAhead $ match "y" (BString "r")
KResponse <$>! "r" <*>! "t"
{-# INLINE fromBEncode #-}
{-----------------------------------------------------------------------
-- Summed messages
-----------------------------------------------------------------------}
data KMessage
= Q KQuery
| R KResponse
| E KError
instance BEncode KMessage where
toBEncode (Q q) = toBEncode q
toBEncode (R r) = toBEncode r
toBEncode (E e) = toBEncode e
fromBEncode b =
Q <$> fromBEncode b
<|> R <$> fromBEncode b
<|> E <$> fromBEncode b
|
