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|
-- |
-- Module : Network.BitTorrent.Core.Node
-- Copyright : (c) Sam Truzjan 2013
-- (c) Daniel Gröber 2013
-- License : BSD3
-- Maintainer : pxqr.sta@gmail.com
-- Stability : experimental
-- Portability : portable
--
-- A \"node\" is a client\/server listening on a UDP port
-- implementing the distributed hash table protocol. The DHT is
-- composed of nodes and stores the location of peers. BitTorrent
-- clients include a DHT node, which is used to contact other nodes
-- in the DHT to get the location of peers to download from using
-- the BitTorrent protocol.
--
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE DeriveDataTypeable #-}
module Network.BitTorrent.Core.Node
( -- * Node ID
NodeId
, testIdBit
, genNodeId
-- * Node address
, NodeAddr (..)
-- * Node info
, NodeInfo (..)
) where
import Control.Applicative
import Data.Aeson (ToJSON, FromJSON)
import Data.Aeson.TH
import Data.Bits
import Data.ByteString as BS
import Data.BEncode as BE
import Data.Default
import Data.Hashable
import Data.IP
import Data.List as L
import Data.Ord
import Data.Serialize as S
import Data.String
import Data.Typeable
import Data.Word
import Network
import System.Entropy
import Data.Torrent.JSON
import Network.BitTorrent.Core.PeerAddr (PeerAddr (..))
{-----------------------------------------------------------------------
-- Node id
-----------------------------------------------------------------------}
-- TODO more compact representation ('ShortByteString's?)
-- | Each node has a globally unique identifier known as the \"node
-- ID.\"
--
-- Normally, /this/ node id should we saved between invocations
-- of the client software.
newtype NodeId = NodeId ByteString
deriving (Show, Eq, Ord, BEncode, FromJSON, ToJSON, Typeable)
nodeIdSize :: Int
nodeIdSize = 20
-- | Meaningless node id, for testing purposes only.
instance Default NodeId where
def = NodeId (BS.replicate nodeIdSize 0)
instance Serialize NodeId where
get = NodeId <$> getByteString nodeIdSize
{-# INLINE get #-}
put (NodeId bs) = putByteString bs
{-# INLINE put #-}
-- | ASCII encoded.
instance IsString NodeId where
fromString str
| L.length str == nodeIdSize = NodeId (fromString str)
| otherwise = error "fromString: invalid NodeId length"
{-# INLINE fromString #-}
-- | Test if the nth bit is set.
testIdBit :: NodeId -> Word -> Bool
testIdBit (NodeId bs) i
| fromIntegral i < nodeIdSize * 8
, (q, r) <- quotRem (fromIntegral i) 8
= testBit (BS.index bs q) r
| otherwise = False
{-# INLINE testIdBit #-}
-- TODO WARN is the 'system' random suitable for this?
-- | Generate random NodeID used for the entire session.
-- Distribution of ID's should be as uniform as possible.
--
genNodeId :: IO NodeId
genNodeId = NodeId <$> getEntropy nodeIdSize
{-----------------------------------------------------------------------
-- Node address
-----------------------------------------------------------------------}
data NodeAddr a = NodeAddr
{ nodeHost :: !a
, nodePort :: {-# UNPACK #-} !PortNumber
} deriving (Show, Eq, Typeable)
$(deriveJSON omitRecordPrefix ''NodeAddr)
-- | KRPC compatible encoding.
instance Serialize a => Serialize (NodeAddr a) where
get = NodeAddr <$> get <*> get
{-# INLINE get #-}
put NodeAddr {..} = put nodeHost >> put nodePort
{-# INLINE put #-}
-- | Torrent file compatible encoding.
instance BEncode a => BEncode (NodeAddr a) where
toBEncode NodeAddr {..} = toBEncode (nodeHost, nodePort)
{-# INLINE toBEncode #-}
fromBEncode b = uncurry NodeAddr <$> fromBEncode b
{-# INLINE fromBEncode #-}
instance Hashable a => Hashable (NodeAddr a) where
hashWithSalt s NodeAddr {..} = hashWithSalt s (nodeHost, nodePort)
{-# INLINE hashWithSalt #-}
-- | Example:
--
-- @nodePort \"127.0.0.1:6881\" == 6881@
--
instance IsString (NodeAddr IPv4) where
fromString = fromPeerAddr . fromString
fromPeerAddr :: PeerAddr a -> NodeAddr a
fromPeerAddr PeerAddr {..} = NodeAddr
{ nodeHost = peerHost
, nodePort = peerPort
}
{-----------------------------------------------------------------------
-- Node info
-----------------------------------------------------------------------}
data NodeInfo a = NodeInfo
{ nodeId :: !NodeId
, nodeAddr :: !(NodeAddr a)
} deriving (Show, Eq)
$(deriveJSON omitRecordPrefix ''NodeInfo)
instance Eq a => Ord (NodeInfo a) where
compare = comparing nodeId
-- | KRPC 'compact list' compatible encoding: contact information for
-- nodes is encoded as a 26-byte string. Also known as "Compact node
-- info" the 20-byte Node ID in network byte order has the compact
-- IP-address/port info concatenated to the end.
instance Serialize a => Serialize (NodeInfo a) where
get = NodeInfo <$> get <*> get
put NodeInfo {..} = put nodeId >> put nodeAddr
|
