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|
-- TODO: tests
-- |
-- Copyright : (c) Sam T. 2013
-- License : MIT
-- Maintainer : pxqr.sta@gmail.com
-- Stability : experimental
-- Portability : non-portable
--
-- This module provides 'Peer' and 'PeerID' datatypes and all related
-- operations.
-- Recommended method for generation of the peer ID's is 'newPeerID',
-- though this module exports some other goodies for custom generation.
--
{-# LANGUAGE OverloadedStrings, GeneralizedNewtypeDeriving #-}
module Network.BitTorrent.PeerID
( -- * Peer addr
Peer(..)
, peerSockAddr, connectToPeer
-- * Peer identification
, PeerID (getPeerID)
-- ** Encoding styles
, azureusStyle, shadowStyle
-- ** Defaults
, defaultClientID, defaultVersionNumber
-- ** Generation
, newPeerID, timestampByteString
-- ** Extra
, byteStringPadded
) where
import Control.Applicative
import Data.Word
import Data.Bits
import Data.BEncode
import Data.ByteString (ByteString)
import qualified Data.ByteString as B
import qualified Data.ByteString.Char8 as BC
import qualified Data.ByteString.Lazy as BL
import qualified Data.ByteString.Builder as B
import Data.Foldable (foldMap)
import Data.Monoid ((<>))
import Data.Serialize
import Data.URLEncoded
import Data.Version (Version(Version), versionBranch)
import Data.Time.Clock (getCurrentTime)
import Data.Time.Format (formatTime)
import System.Locale (defaultTimeLocale)
import Network
import Network.Socket
-- TODO we have linker error here, so manual hardcoded version for a while.
-- import Paths_network_bittorrent (version)
version :: Version
version = Version [0, 10, 0, 0] []
data Peer = Peer {
peerID :: Maybe PeerID
, peerIP :: HostAddress
, peerPort :: PortNumber
} deriving Show
-- TODO make platform independent, clarify htonl
-- | Convert peer info from tracker response to socket address.
-- Used for establish connection between peers.
--
peerSockAddr :: Peer -> SockAddr
peerSockAddr = SockAddrInet <$> (g . peerPort) <*> (htonl . peerIP)
where
htonl :: Word32 -> Word32
htonl d =
((d .&. 0xff) `shiftL` 24) .|.
(((d `shiftR` 8 ) .&. 0xff) `shiftL` 16) .|.
(((d `shiftR` 16) .&. 0xff) `shiftL` 8) .|.
((d `shiftR` 24) .&. 0xff)
g :: PortNumber -> PortNumber
g = id
-- ipv6 extension
-- | Tries to connect to peer using reasonable default parameters.
--
connectToPeer :: Peer -> IO Socket
connectToPeer p = do
sock <- socket AF_INET Stream Network.Socket.defaultProtocol
connect sock (peerSockAddr p)
return sock
-- | Peer identifier is exactly 20 bytes long bytestring.
newtype PeerID = PeerID { getPeerID :: ByteString }
deriving (Show, Eq, Ord, BEncodable)
instance Serialize PeerID where
put = putByteString . getPeerID
get = PeerID <$> getBytes 20
instance URLShow PeerID where
urlShow = BC.unpack . getPeerID
-- | Azureus-style encoding have the following layout:
--
-- * 1 byte : '-'
--
-- * 2 bytes: client id
--
-- * 4 bytes: version number
--
-- * 1 byte : '-'
--
-- * 12 bytes: random number
--
azureusStyle :: ByteString -- ^ 2 character client ID, padded with 'H'.
-> ByteString -- ^ Version number, padded with 'X'.
-> ByteString -- ^ Random number, padded with '0'.
-> PeerID -- ^ Azureus-style encoded peer ID.
azureusStyle cid ver rnd = PeerID $ BL.toStrict $ B.toLazyByteString $
B.char8 '-' <>
byteStringPadded cid 2 'H' <>
byteStringPadded ver 4 'X' <>
B.char8 '-' <>
byteStringPadded rnd 12 '0'
-- | Shadow-style encoding have the following layout:
--
-- * 1 byte : client id.
--
-- * 0-4 bytes: version number. If less than 4 then padded with '-' char.
--
-- * 15 bytes : random number. If length is less than 15 then padded with '0' char.
--
shadowStyle :: Char -- ^ Client ID.
-> ByteString -- ^ Version number.
-> ByteString -- ^ Random number.
-> PeerID -- ^ Shadow style encoded peer ID.
shadowStyle cid ver rnd = PeerID $ BL.toStrict $ B.toLazyByteString $
B.char8 cid <>
byteStringPadded ver 4 '-' <>
byteStringPadded rnd 15 '0'
-- | "HS" - 2 bytes long client identifier.
defaultClientID :: ByteString
defaultClientID = "HS"
-- | Gives exactly 4 bytes long version number for any version of the package.
-- Version is taken from .cabal.
defaultVersionNumber :: ByteString
defaultVersionNumber = B.take 4 (BC.pack (foldMap show (versionBranch version)))
-- | Gives 15 characters long decimal timestamp such that:
--
-- * 6 bytes : first 6 characters from picoseconds obtained with %q.
--
-- * 1 bytes : character '.' for readability.
--
-- * 9..* bytes: number of whole seconds since the Unix epoch (!)REVERSED.
--
-- Can be used both with shadow and azureus style encoding. This format is
-- used to make the ID's readable(for debugging) and more or less random.
--
timestampByteString :: IO ByteString
timestampByteString = (BC.pack . format) <$> getCurrentTime
where
format t = take 6 (formatTime defaultTimeLocale "%q" t) ++ "." ++
take 9 (reverse (formatTime defaultTimeLocale "%s" t))
-- | Here we use Azureus-style encoding with the following args:
--
-- * 'HS' for the client id.
--
-- * Version of the package for the version number
--
-- * UTC time day ++ day time for the random number.
--
newPeerID :: IO PeerID
newPeerID = azureusStyle defaultClientID defaultVersionNumber
<$> timestampByteString
-- | Pad bytestring so it's becomes exactly request length. Conversion is done
-- like so:
--
-- * length < size: Complete bytestring by given charaters.
--
-- * length = size: Output bytestring as is.
--
-- * length > size: Drop last (length - size) charaters from a given bytestring.
--
byteStringPadded :: ByteString -- ^ bytestring to be padded.
-> Int -- ^ size of result builder.
-> Char -- ^ character used for padding.
-> B.Builder
byteStringPadded bs s c =
B.byteString (B.take s bs) <>
B.byteString (BC.replicate padLen c)
where
padLen = s - min (B.length bs) s
|
