implement p2p command

Command/P2P.hs

@@ -0,0 +1,61 @@
+{- git-annex command
+ -
+ - Copyright 2016 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Command.P2P where
+
+import Command
+import Git.Types
+import P2P.Address
+import P2P.Auth
+import Utility.AuthToken
+
+cmd :: Command
+cmd = command "p2p" SectionSetup
+	"configure peer-2-peer links between repositories"
+	paramNothing (seek <$$> optParser)
+
+data P2POpts
+	= GenAddresses
+	| LinkRemote P2PAddressAuth RemoteName
+
+optParser :: CmdParamsDesc -> Parser P2POpts 
+optParser _ = genaddresses <|> linkremote
+  where
+	genaddresses = flag' GenAddresses
+		( long "gen-addresses"
+		<> help "generate addresses that allow accessing this repository over P2P networks"
+		)
+	linkremote = LinkRemote
+		<$> option readaddr
+			( long "link"
+			<> metavar paramAddress
+			<> help "address of the peer to link with"
+			)
+		<*> strOption
+			( long "named"
+			<> metavar paramRemote
+			<> help "specify name to use for git remote"
+			)
+	readaddr = eitherReader $ maybe (Left "address parse error") Right
+		. unformatP2PAddress
+
+seek :: P2POpts -> CommandSeek
+seek GenAddresses = do
+	addrs <- loadP2PAddresses
+	if null addrs
+		then giveup "No P2P networks are currrently available."
+		else do
+			authtoken <- liftIO $ genAuthToken 128
+			storeP2PAuthToken authtoken
+			-- Only addresses are output to stdout, to allow
+			-- scripting.
+			earlyWarning "These addresses allow access to this git-annex repository. Only share them with people you trust with that access, using trusted communication channels!"
+			liftIO $ putStr $ unlines $
+				map formatP2PAddress $
+				map (`P2PAddressAuth` authtoken) addrs
+seek (LinkRemote addr name) = do
+