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|
-- |
-- Copyright : (c) Sam T. 2013
-- License : MIT
-- Maintainer : pxqr.sta@gmail.com
-- Stability : experimental
-- Portability : non-portable
--
-- The tracker is an HTTP/HTTPS service used to discovery peers for
-- a particular existing torrent and keep statistics about the
-- swarm. This module also provides a way to easily request scrape
-- info for a particular torrent list.
--
-- For more information see:
-- <https://wiki.theory.org/BitTorrentSpecification#Tracker_HTTP.2FHTTPS_Protocol>
--
module Network.BitTorrent.Tracker.HTTP
( askTracker, leaveTracker
, scrapeURL, scrape, scrapeOne
) where
import Control.Applicative
import Control.Monad
import Data.BEncode
import Data.ByteString as B
import Data.ByteString.Char8 as BC
import Data.List as L
import Data.Map as M
import Data.Monoid
import Data.URLEncoded as URL
import Network.URI
import Network.HTTP
import Data.Torrent.Metainfo hiding (announce)
import Network.BitTorrent.Tracker.Protocol
data HTTPTracker = HTTPTracker URI
instance Tracker URI where
announce = askTracker
scrape_ uri ihs = do
e <- scrape uri ihs
case e of
Left str -> error str
Right si -> return si
{-----------------------------------------------------------------------
Announce
-----------------------------------------------------------------------}
encodeRequest :: URI -> AnnounceQuery -> URI
encodeRequest announce req = URL.urlEncode req
`addToURI` announce
`addHashToURI` reqInfoHash req
mkGET :: URI -> Request ByteString
mkGET uri = Request uri GET [] ""
-- TODO rename to something like "announceBlahBlah"
-- | Send request and receive response from the tracker specified in
-- announce list. This function throws 'IOException' if it couldn't
-- send request or receive response or decode response.
--
askTracker :: URI -> AnnounceQuery -> IO AnnounceInfo
askTracker announce req = do
let r = mkGET (encodeRequest announce req)
rawResp <- simpleHTTP r
respBody <- getResponseBody rawResp
checkResult $ decoded respBody
where
checkResult (Left err)
= ioError $ userError $ err ++ " in tracker response"
checkResult (Right (Failure err))
= ioError $ userError $ show err ++ " in tracker response"
checkResult (Right resp) = return resp
-- | The same as the 'askTracker' but ignore response. Used in
-- conjunction with 'Stopped'.
leaveTracker :: URI -> AnnounceQuery -> IO ()
leaveTracker announce req = do
let r = mkGET (encodeRequest announce req)
void $ simpleHTTP r >>= getResponseBody
{-----------------------------------------------------------------------
Scrape
-----------------------------------------------------------------------}
-- | Trying to convert /announce/ URL to /scrape/ URL. If 'scrapeURL'
-- gives 'Nothing' then tracker do not support scraping. The info hash
-- list is used to restrict the tracker's report to that particular
-- torrents. Note that scrapping of multiple torrents may not be
-- supported. (Even if scrapping convention is supported)
--
scrapeURL :: URI -> [InfoHash] -> Maybe URI
scrapeURL uri ihs = do
newPath <- replace (BC.pack (uriPath uri))
let newURI = uri { uriPath = BC.unpack newPath }
return (L.foldl addHashToURI newURI ihs)
where
replace :: ByteString -> Maybe ByteString
replace p
| ps <- BC.splitWith (== '/') p
, "announce" `B.isPrefixOf` L.last ps
= let newSuff = "scrape" <> B.drop (B.length "announce") (L.last ps)
in Just (B.intercalate "/" (L.init ps ++ [newSuff]))
| otherwise = Nothing
-- | For each 'InfoHash' of torrents request scrape info from the tracker.
-- However if the info hash list is 'null', the tracker should list
-- all available torrents.
-- Note that the 'URI' should be /announce/ URI, not /scrape/ URI.
--
scrape :: URI -- ^ Announce 'URI'.
-> [InfoHash] -- ^ Torrents to be scrapped.
-> IO (Result Scrape) -- ^ 'ScrapeInfo' for each torrent.
scrape announce ihs
| Just uri<- scrapeURL announce ihs = do
rawResp <- simpleHTTP (Request uri GET [] "")
respBody <- getResponseBody rawResp
return (decoded (BC.pack respBody))
| otherwise = return (Left "Tracker do not support scraping")
-- | More particular version of 'scrape', just for one torrent.
--
scrapeOne :: URI -- ^ Announce 'URI'
-> InfoHash -- ^ Hash of the torrent info.
-> IO (Result ScrapeInfo) -- ^ 'ScrapeInfo' for the torrent.
scrapeOne uri ih = extract <$> scrape uri [ih]
where
extract (Right m)
| Just s <- M.lookup ih m = Right s
| otherwise = Left "unable to find info hash in response dict"
extract (Left e) = Left e
|