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|
-- |
-- Copyright : (c) Sam Truzjan 2013
-- License : BSD3
-- Maintainer : pxqr.sta@gmail.com
-- Stability : experimental
-- Portability : non-portable
--
-- This module provides high level API for peer -> tracker
-- communication. Tracker is used to discover other peers in the
-- network using torrent info hash.
--
{-# LANGUAGE TemplateHaskell #-}
module Network.BitTorrent.Tracker
( -- * Connection
TConnection(..)
, tconnection
-- * Session
, TSession
, tracker
-- * Re-export
, defaultPorts
, ScrapeInfo
) where
import Control.Applicative
import Control.Concurrent
import Control.Concurrent.BoundedChan as BC
import Control.Concurrent.STM
import Control.Exception
import Control.Monad
import Data.List as L
import Data.IORef
import Data.Text as T
import Network
import Network.URI
import Data.Torrent
import Network.BitTorrent.Peer
import Network.BitTorrent.Tracker.Protocol as Tracker
import Network.BitTorrent.Tracker.HTTP
import Network.BitTorrent.Tracker.UDP
{-----------------------------------------------------------------------
Tracker connection
-----------------------------------------------------------------------}
-- | 'TConnection' (shorthand for Tracker session) combines tracker
-- request fields neccessary for tracker, torrent and client
-- identification.
--
-- This data is considered as static within one session.
--
data TConnection = TConnection {
tconnAnnounce :: URI
-- ^ Announce URL.
, tconnInfoHash :: InfoHash
-- ^ Hash of info part of current .torrent file.
, tconnPeerId :: PeerId
-- ^ Client peer ID.
, tconnPort :: PortNumber
-- ^ The port number the client is listenning on.
} deriving Show
-- TODO tconnection :: SwarmSession -> TConnection
tconnection :: Torrent -> PeerId -> PortNumber -> TConnection
tconnection t = TConnection (tAnnounce t) (tInfoHash t)
-- | used to avoid boilerplate; do NOT export me
genericReq :: TConnection -> Progress -> AnnounceQuery
genericReq ses pr = AnnounceQuery {
reqInfoHash = tconnInfoHash ses
, reqPeerId = tconnPeerId ses
, reqPort = tconnPort ses
, reqProgress = pr
, reqIP = Nothing
, reqNumWant = Nothing
, reqEvent = Nothing
}
-- | The first request to the tracker that should be created is
-- 'startedReq'. It includes necessary 'Started' event field.
--
startedReq :: TConnection -> Progress -> AnnounceQuery
startedReq ses pr = (genericReq ses pr)
{ reqNumWant = Just defaultNumWant
, reqEvent = Just Started
}
-- | Regular request must be sent to keep track new peers and
-- notify tracker about current state of the client
-- so new peers could connect to the client.
--
regularReq :: Int -> TConnection -> Progress -> AnnounceQuery
regularReq numWant ses pr = (genericReq ses pr)
{ reqNumWant = Just numWant
, reqEvent = Nothing
}
-- | Must be sent to the tracker if the client is shutting down
-- gracefully.
--
stoppedReq :: TConnection -> Progress -> AnnounceQuery
stoppedReq ses pr = (genericReq ses pr)
{ reqNumWant = Nothing
, reqEvent = Just Stopped
}
-- | Must be sent to the tracker when the download completes.
-- However, must not be sent if the download was already 100%
-- complete.
--
completedReq :: TConnection -> Progress -> AnnounceQuery
completedReq ses pr = (genericReq ses pr)
{ reqNumWant = Nothing
, reqEvent = Just Completed
}
{-----------------------------------------------------------------------
Tracker session
-----------------------------------------------------------------------}
{- Why use BoundedChan?
Because most times we need just a list of peer at the start and all
the rest time we will take little by little. On the other hand tracker
will give us some constant count of peers and channel will grow with
time. To avoid space leaks and long lists of peers (which we don't
need) we use bounded chaan.
Chan size.
Should be at least (count_of_workers * 2) to accumulate long enough
peer list.
Order of peers in chan.
Old peers in head, new ones in tail. Old peers should be used in the
first place because by statistics they are most likely will present in
network a long time than a new.
-}
type TimeInterval = Int
waitInterval :: TSession -> IO ()
waitInterval TSession {..} = do
delay <- readIORef seInterval
threadDelay (delay * sec)
where
sec = 1000 * 1000 :: Int
data TSession = TSession
{ seConnection :: !TConnection
, seTracker :: !BitTracker
, seProgress :: !(TVar Progress)
, sePeers :: !(BoundedChan PeerAddr)
, seInterval :: {-# UNPACK #-} !(IORef TimeInterval)
}
openSession :: BoundedChan PeerAddr
-> TVar Progress
-> TConnection -> IO TSession
openSession chan progress conn @ TConnection {..} = do
trac <- Tracker.connect tconnAnnounce
pr <- readTVarIO progress
resp <- Tracker.announce trac $ startedReq conn pr
print resp
case resp of
Failure e -> throwIO $ userError $ T.unpack e
AnnounceInfo {..} -> do
-- TODO make use of rest AnnounceInfo fields
BC.writeList2Chan chan respPeers
TSession conn trac progress chan
<$> newIORef respInterval
closeSession :: TSession -> IO ()
closeSession TSession {..} = do
pr <- readTVarIO seProgress
_ <- Tracker.announce seTracker (stoppedReq seConnection pr)
return ()
withSession :: BoundedChan PeerAddr
-> TVar Progress
-> TConnection -> (TSession -> IO a) -> IO a
withSession chan prog conn
= bracket (openSession chan prog conn) closeSession
askPeers :: TSession -> IO ()
askPeers se @ TSession {..} = forever $ do
waitInterval se
pr <- readTVarIO seProgress
resp <- tryJust isIOException $ do
let req = regularReq defaultNumWant seConnection pr
Tracker.announce seTracker req
print resp
case resp of
Left _ -> return ()
Right (Failure e) -> throwIO $ userError $ T.unpack e
Right (AnnounceInfo {..}) -> do
writeIORef seInterval respInterval
-- we rely on the fact that union on lists is not
-- commutative: this implements the heuristic "old peers
-- in head"
old <- BC.getChanContents sePeers
let combined = L.union old respPeers
BC.writeList2Chan sePeers combined
where
isIOException :: IOException -> Maybe IOException
isIOException = return
tracker :: BoundedChan PeerAddr -> TVar Progress -> TConnection -> IO ()
tracker chan prog conn = withSession chan prog conn askPeers
|
