Added bittorrent special remote

addurl behavior change: When downloading an url ending in .torrent,
it will download files from bittorrent, instead of the old behavior
of adding the torrent file to the repository.

Added Recommends on aria2 and bittornado | bittorrent.

This commit was sponsored by Asbjørn Sloth Tønnesen.

2 files changed, 344 insertions, 0 deletions

diff --git a/Remote/BitTorrent.hs b/Remote/BitTorrent.hs
new file mode 100644
index 000000000..aaedcd0ef
--- /dev/null
+++ b/Remote/BitTorrent.hs
@@ -0,0 +1,342 @@
+{- BitTorrent remote.
+ -
+ - Copyright 2014 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Remote.BitTorrent (remote) where
+
+import Common.Annex
+import Types.Remote
+import qualified Annex
+import qualified Git
+import qualified Git.Construct
+import Config.Cost
+import Logs.Web
+import Logs.Trust.Basic
+import Types.TrustLevel
+import Types.UrlContents
+import Types.CleanupActions
+import Utility.Metered
+import Utility.Tmp
+import Backend.URL
+import Annex.Perms
+import qualified Annex.Url as Url
+
+import qualified Data.Map as M
+import Network.URI
+
+-- Dummy uuid for bittorrent. Do not alter.
+bitTorrentUUID :: UUID
+bitTorrentUUID = UUID "00000000-0000-0000-0000-000000000002"
+
+remote :: RemoteType
+remote = RemoteType {
+	typename = "bittorrent",
+	enumerate = list,
+	generate = gen,
+	setup = error "not supported"
+}
+
+-- There is only one bittorrent remote, and it always exists.
+list :: Annex [Git.Repo]
+list = do
+	r <- liftIO $ Git.Construct.remoteNamed "bittorrent" Git.Construct.fromUnknown
+	return [r]
+
+gen :: Git.Repo -> UUID -> RemoteConfig -> RemoteGitConfig -> Annex (Maybe Remote)
+gen r _ c gc = 
+	return $ Just Remote
+		{ uuid = bitTorrentUUID
+		, cost = expensiveRemoteCost
+		, name = Git.repoDescribe r
+		, storeKey = uploadKey
+		, retrieveKeyFile = downloadKey
+		, retrieveKeyFileCheap = downloadKeyCheap
+		, removeKey = dropKey
+		, checkPresent = checkKey
+		, checkPresentCheap = False
+		, whereisKey = Nothing
+		, remoteFsck = Nothing
+		, repairRepo = Nothing
+		, config = c
+		, gitconfig = gc
+		, localpath = Nothing
+		, repo = r
+		, readonly = True
+		, availability = GloballyAvailable
+		, remotetype = remote
+		, mkUnavailable = return Nothing
+		, getInfo = return []
+		, claimUrl = Just (pure . isSupportedUrl)
+		, checkUrl = Just checkTorrentUrl
+		}
+
+downloadKey :: Key -> AssociatedFile -> FilePath -> MeterUpdate -> Annex Bool
+downloadKey key _file dest p = do
+	defaultUnTrusted
+	get . map (torrentUrlNum . fst . getDownloader) =<< getBitTorrentUrls key
+  where
+	get [] = do
+		warning "no known torrent url"
+		return False
+	get urls = do
+		showOutput -- make way for download progress bar
+		untilTrue urls $ \(u, filenum) -> do
+			registerTorrentCleanup u
+			checkDependencies
+			unlessM (downloadTorrentFile u) $
+				error "could not download torrent file"
+			downloadTorrentContent u dest filenum p
+
+downloadKeyCheap :: Key -> FilePath -> Annex Bool
+downloadKeyCheap _ _ = return False
+
+uploadKey :: Key -> AssociatedFile -> MeterUpdate -> Annex Bool
+uploadKey _ _ _ = do
+	warning "upload to bittorrent not supported"
+	return False
+
+dropKey :: Key -> Annex Bool
+dropKey k = do
+	mapM_ (setUrlMissing bitTorrentUUID k) =<< getBitTorrentUrls k
+	return True
+
+{- This is a very poor check, but checking if a torrent has enough seeders
+ - with all the pieces etc is quite hard.. and even if implemented, it
+ - tells us nothing about the later state of the torrent.
+ -
+ - This is why this remote needs to default to untrusted!
+ -}
+checkKey :: Key -> Annex Bool
+checkKey key = not . null <$> getBitTorrentUrls key
+
+-- Makes this remote UnTrusted, unless it already has a trust set.
+defaultUnTrusted :: Annex ()
+defaultUnTrusted = whenM (isNothing . M.lookup bitTorrentUUID <$> trustMapRaw) $
+	trustSet bitTorrentUUID UnTrusted
+
+getBitTorrentUrls :: Key -> Annex [URLString]
+getBitTorrentUrls key = filter supported <$> getUrls key
+  where
+	supported u =
+		let (u', dl) = (getDownloader u)
+		in dl == OtherDownloader && isSupportedUrl u'
+
+isSupportedUrl :: URLString -> Bool
+isSupportedUrl u = isTorrentMagnetUrl u || isTorrentUrl u
+
+isTorrentUrl :: URLString -> Bool
+isTorrentUrl = maybe False (\u -> ".torrent" `isSuffixOf` uriPath u) . parseURI
+
+isTorrentMagnetUrl :: URLString -> Bool
+isTorrentMagnetUrl u = "magnet:" `isPrefixOf` u && checkbt (parseURI u)
+  where
+	checkbt (Just uri) | "xt=urn:btih:" `isInfixOf` uriQuery uri = True
+	checkbt _ = False
+
+checkTorrentUrl :: URLString -> Annex UrlContents
+checkTorrentUrl u = do
+	checkDependencies
+	registerTorrentCleanup u
+	ifM (downloadTorrentFile u)
+		( torrentContents u
+		, error "could not download torrent file"
+		)
+
+{- To specify which file inside a multi-url torrent, the file number is
+ - appended to the url. -}
+torrentUrlWithNum :: URLString -> Int -> URLString
+torrentUrlWithNum u n = u ++ "#" ++ show n
+
+torrentUrlNum :: URLString -> (URLString, Int)
+torrentUrlNum u =
+	let (n, ru) = separate (== '#') (reverse u)
+	in (reverse ru, fromMaybe 1 $ readish $ reverse n)
+
+{- A Key corresponding to the URL of a torrent file. -}
+torrentUrlKey :: URLString -> Annex Key
+torrentUrlKey u = fromUrl (fst $ torrentUrlNum u) Nothing
+
+{- Temporary directory used to download a torrent. -}
+tmpTorrentDir :: URLString -> Annex FilePath
+tmpTorrentDir u = do
+	d <- fromRepo gitAnnexTmpMiscDir
+	f <- keyFile <$> torrentUrlKey u
+	return (d </> f)
+
+{- Temporary filename to use to store the torrent file. -}
+tmpTorrentFile :: URLString -> Annex FilePath
+tmpTorrentFile u = fromRepo . gitAnnexTmpObjectLocation =<< torrentUrlKey u
+
+{- A cleanup action is registered to delete the torrent file and its
+ - associated temp directory when git-annex exits.
+ -
+ - This allows multiple actions that use the same torrent file and temp
+ - directory to run in a single git-annex run.
+ -}
+registerTorrentCleanup :: URLString -> Annex ()
+registerTorrentCleanup u = Annex.addCleanup (TorrentCleanup u) $ do
+	liftIO . nukeFile =<< tmpTorrentFile u
+	d <- tmpTorrentDir u
+	liftIO $ whenM (doesDirectoryExist d) $
+		removeDirectoryRecursive d
+
+{- Downloads the torrent file. (Not its contents.) -}
+downloadTorrentFile :: URLString -> Annex Bool
+downloadTorrentFile u = do
+	torrent <- tmpTorrentFile u
+	ifM (liftIO $ doesFileExist torrent)
+		( return True
+		, do
+			showAction "downloading torrent file"
+			showOutput
+			createAnnexDirectory (parentDir torrent)
+			if isTorrentMagnetUrl u
+				then do
+					tmpdir <- tmpTorrentDir u
+					let metadir = tmpdir </> "meta"
+					createAnnexDirectory metadir
+					ok <- downloadMagnetLink u metadir torrent
+					liftIO $ removeDirectoryRecursive metadir
+					return ok
+				else do
+					misctmp <- fromRepo gitAnnexTmpMiscDir
+					withTmpFileIn misctmp "torrent" $ \f _h -> do
+						ok <- Url.withUrlOptions $ Url.download u f
+						when ok $
+							liftIO $ renameFile f torrent
+						return ok
+		)
+
+downloadMagnetLink :: URLString -> FilePath -> FilePath -> Annex Bool
+downloadMagnetLink u metadir dest = ifM download
+	( liftIO $ do
+		ts <- filter (".torrent" `isPrefixOf`)
+			<$> dirContents metadir
+		case ts of
+			(t:[]) -> do
+				renameFile t dest
+				return True
+			_ -> return False
+	, return False
+	)
+  where
+	download = runAria
+		[ Param "--bt-metadata-only"
+		, Param "--bt-save-metadata"
+		, Param u
+		, Param "--seed-time=0"
+		, Param "-d"
+		, File metadir
+		]
+
+downloadTorrentContent :: URLString -> FilePath -> Int -> MeterUpdate -> Annex Bool
+downloadTorrentContent u dest filenum p = do
+	torrent <- tmpTorrentFile u
+	tmpdir <- tmpTorrentDir u
+	createAnnexDirectory tmpdir
+	f <- wantedfile torrent
+	showOutput
+	ifM (download torrent tmpdir <&&> liftIO (doesFileExist (tmpdir </> f)))
+		( do
+			liftIO $ renameFile (tmpdir </> f) dest
+			return True
+		, return False
+		)
+  where
+	-- TODO parse aria's output and update progress meter
+	download torrent tmpdir = runAria
+		[ Param $ "--select-file=" ++ show filenum
+		, File torrent
+		, Param "-d"
+		, File tmpdir
+		, Param "--seed-time=0"
+		]
+	
+	{- aria2c will create part of the directory structure
+	 - contained in the torrent. It may download parts of other files
+	 - in addition to the one we asked for. So, we need to find
+	 - out the filename we want based on the filenum.
+	 -}
+	wantedfile torrent = do
+		fs <- liftIO $ map fst <$> torrentFileSizes torrent
+		if length fs >= filenum
+			then return (fs !! filenum)
+			else error "Number of files in torrent seems to have changed."
+
+checkDependencies :: Annex ()
+checkDependencies = do
+	missing <- liftIO $ filterM (not <$$> inPath) ["aria2c", "btshowmetainfo"]
+	unless (null missing) $
+		error $ "need to install additional software in order to download from bittorrent: " ++ unwords missing
+
+runAria :: [CommandParam] -> Annex Bool
+runAria ps = do
+	opts <- map Param . annexAriaTorrentOptions <$> Annex.getGitConfig
+	liftIO $ boolSystem "aria2c" (ps ++ opts)
+
+btshowmetainfo :: FilePath -> String -> IO [String]
+btshowmetainfo torrent field = 
+	findfield [] . lines <$> readProcess "btshowmetainfo" [torrent]
+  where
+	findfield c [] = reverse c
+	findfield c (l:ls)
+		| l == fieldkey = multiline c ls
+		| fieldkey `isPrefixOf` l =
+			findfield ((drop (length fieldkey) l):c) ls
+		| otherwise = findfield c ls
+
+	multiline c (l:ls)
+		| "   " `isPrefixOf` l = multiline (drop 3 l:c) ls
+		| otherwise = findfield c ls
+	multiline c [] = findfield c []
+
+	fieldkey = field ++ take (14 - length field) (repeat '.') ++ ": "
+
+{- Examines the torrent file and gets the list of files in it,
+ - and their sizes.
+ -}
+torrentFileSizes :: FilePath -> IO [(FilePath, Integer)]
+torrentFileSizes torrent = do
+	files <- getfield "files"
+	if null files
+		then do
+			fnl <- getfield "file name"
+			szl <- map readish <$> getfield "file size"
+			case (fnl, szl) of
+				((fn:[]), (Just sz:[])) -> return [(scrub fn, sz)]
+		 		_ -> parsefailed (show (fnl, szl))
+		else do
+			v <- btshowmetainfo torrent "directory name"
+			case v of
+				(d:[]) -> return $ map (splitsize d) files
+				_ -> parsefailed (show v)
+  where
+	getfield = btshowmetainfo torrent
+
+	parsefailed s = error $ "failed to parse btshowmetainfo output for torrent file: " ++ show s
+
+	-- btshowmetainfo outputs a list of "filename (size)"
+	splitsize d l = (scrub (d </> fn), sz)
+	  where
+		sz = fromMaybe (parsefailed l) $ readish $ 
+			reverse $ takeWhile (/= '(') $ dropWhile (== ')') $
+				reverse l
+		fn = reverse $ drop 2 $
+			dropWhile (/= '(') $ dropWhile (== ')') $ reverse l
+
+	scrub f = if isAbsolute f || any (== "..") (splitPath f)
+		then error "found unsafe filename in torrent!"
+		else f
+
+torrentContents :: URLString -> Annex UrlContents
+torrentContents u = convert
+	<$> (liftIO . torrentFileSizes =<< tmpTorrentFile u)
+  where
+	convert [(fn, sz)] = UrlContents (Just sz) (Just (mkSafeFilePath fn))
+	convert l = UrlMulti $ map mkmulti (zip l [1..])
+
+	mkmulti ((fn, sz), n) = 
+		(torrentUrlWithNum u n, Just sz, mkSafeFilePath fn)
diff --git a/Remote/List.hs b/Remote/List.hs
index 1ec2c32b4..a4d18c7c8 100644
--- a/Remote/List.hs
+++ b/Remote/List.hs
@@ -30,6 +30,7 @@ import qualified Remote.Bup
 import qualified Remote.Directory
 import qualified Remote.Rsync
 import qualified Remote.Web
+import qualified Remote.BitTorrent
 #ifdef WITH_WEBDAV
 import qualified Remote.WebDAV
 #endif
@@ -52,6 +53,7 @@ remoteTypes =
 	, Remote.Directory.remote
 	, Remote.Rsync.remote
 	, Remote.Web.remote
+	, Remote.BitTorrent.remote
 #ifdef WITH_WEBDAV
 	, Remote.WebDAV.remote
 #endif