Revert "p2p --link now defaults to setting up a bi-directional link"

This reverts commit 6aa7e136b5d246228723f4c9996bda11f66c4445.

On second thought, this was an overcomplication of what should be the
lowest-level primitive. Let's build bi-directional links at the pairing
level with eg magic wormhole.

7 files changed, 56 insertions, 131 deletions

diff --git a/CHANGELOG b/CHANGELOG
index c4d3e2712..b4659fa02 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -14,10 +14,6 @@ git-annex (6.20161211) UNRELEASED; urgency=medium
     be processed without requiring it to be in the current encoding.
   * p2p: --link no longer takes a remote name, instead the --name
     option can be used.
-  * p2p --link now defaults to setting up a bi-directional link;
-    both the local and remote git repositories get remotes added
-    pointing at one-another.
-  * p2p: Added --one-way option.
 
  -- Joey Hess <id@joeyh.name>  Sun, 11 Dec 2016 21:29:51 -0400
 
diff --git a/Command/P2P.hs b/Command/P2P.hs
index 817840d07..d59d774c4 100644
--- a/Command/P2P.hs
+++ b/Command/P2P.hs
@@ -10,10 +10,15 @@ module Command.P2P where
 import Command
 import P2P.Address
 import P2P.Auth
-import P2P.Annex
+import P2P.IO
+import qualified P2P.Protocol as P2P
 import Utility.AuthToken
 import Git.Types
 import qualified Git.Remote
+import qualified Git.Command
+import qualified Annex
+import Annex.UUID
+import Config
 
 cmd :: Command
 cmd = command "p2p" SectionSetup
@@ -24,13 +29,10 @@ data P2POpts
 	= GenAddresses
 	| LinkRemote
 
-data LinkDirection = BiDirectional | OneWay
-
-optParser :: CmdParamsDesc -> Parser (P2POpts, Maybe RemoteName, LinkDirection)
-optParser _ = (,,)
+optParser :: CmdParamsDesc -> Parser (P2POpts, Maybe RemoteName)
+optParser _ = (,)
 	<$> (genaddresses <|> linkremote)
 	<*> optional name
-	<*> direction
   where
 	genaddresses = flag' GenAddresses
 		( long "gen-addresses"
@@ -45,17 +47,23 @@ optParser _ = (,,)
 		<> metavar paramName
 		<> help "name of remote"
 		)
-	direction = flag BiDirectional OneWay
-		( long "one-way"
-		<> help "make one-way link, rather than default bi-directional link"
-		)
 
-seek :: (P2POpts, Maybe RemoteName, LinkDirection) -> CommandSeek
-seek (GenAddresses, _, _) = genAddresses =<< loadP2PAddresses
-seek (LinkRemote, Just name, direction) = commandAction $
-	linkRemote direction (Git.Remote.makeLegalName name)
-seek (LinkRemote, Nothing, direction) = commandAction $
-	linkRemote direction =<< unusedPeerRemoteName
+seek :: (P2POpts, Maybe RemoteName) -> CommandSeek
+seek (GenAddresses, _) = genAddresses =<< loadP2PAddresses
+seek (LinkRemote, Just name) = commandAction $
+	linkRemote (Git.Remote.makeLegalName name)
+seek (LinkRemote, Nothing) = commandAction $
+	linkRemote =<< unusedPeerRemoteName
+
+unusedPeerRemoteName :: Annex RemoteName
+unusedPeerRemoteName = go (1 :: Integer) =<< usednames
+  where
+	usednames = mapMaybe remoteName . remotes <$> Annex.gitRepo
+	go n names = do
+		let name = "peer" ++ show n
+		if name `elem` names
+			then go (n+1) names
+			else return name
 
 -- Only addresses are output to stdout, to allow scripting.
 genAddresses :: [P2PAddress] -> Annex ()
@@ -69,8 +77,8 @@ genAddresses addrs = do
 			map (`P2PAddressAuth` authtoken) addrs
 
 -- Address is read from stdin, to avoid leaking it in shell history.
-linkRemote :: LinkDirection -> RemoteName -> CommandStart
-linkRemote direction remotename = do
+linkRemote :: RemoteName -> CommandStart
+linkRemote remotename = do
 	showStart "p2p link" remotename
 	next $ next prompt
   where
@@ -87,13 +95,24 @@ linkRemote direction remotename = do
 				Nothing -> do
 					liftIO $ hPutStrLn stderr "Unable to parse that address, please check its format and try again."
 					prompt
-				Just addr -> do
-					linkbackto <- case direction of
-						OneWay -> return []
-						BiDirectional -> do
-							myaddrs <- loadP2PAddresses
-							authtoken <- liftIO $ genAuthToken 128
-							storeP2PAuthToken authtoken
-							return $ map (`P2PAddressAuth` authtoken) myaddrs
-					linkAddress addr linkbackto remotename
-						>>= either giveup return
+				Just addr -> setup addr
+	setup (P2PAddressAuth addr authtoken) = do
+		g <- Annex.gitRepo
+		conn <- liftIO $ connectPeer g addr
+			`catchNonAsync` connerror
+		u <- getUUID
+		v <- liftIO $ runNetProto conn $ P2P.auth u authtoken
+		case v of
+			Right (Just theiruuid) -> do
+				ok <- inRepo $ Git.Command.runBool
+					[ Param "remote", Param "add"
+					, Param remotename
+					, Param (formatP2PAddress addr)
+					]
+				when ok $ do
+					storeUUIDIn (remoteConfig remotename "uuid") theiruuid
+					storeP2PRemoteAuthToken addr authtoken
+				return ok
+			Right Nothing -> giveup "Unable to authenticate with peer. Please check the address and try again."
+			Left e -> giveup $ "Unable to authenticate with peer: " ++ e
+	connerror e = giveup $ "Unable to connect with peer. Please check that the peer is connected to the network, and try again. ("  ++ show e ++ ")"
diff --git a/P2P/Address.hs b/P2P/Address.hs
index 919739327..1b1f66059 100644
--- a/P2P/Address.hs
+++ b/P2P/Address.hs
@@ -14,7 +14,6 @@ import Git.Types
 import Creds
 import Utility.AuthToken
 import Utility.Tor
-import qualified Utility.SimpleProtocol as Proto
 
 import qualified Data.Text as T
 
@@ -47,10 +46,6 @@ instance FormatP2PAddress P2PAddress where
 			return (TorAnnex (OnionAddress onionaddr) onionport)
 		| otherwise = Nothing
 
-instance Proto.Serializable P2PAddressAuth where
-	serialize = formatP2PAddress
-	deserialize = unformatP2PAddress
-
 torAnnexScheme :: String
 torAnnexScheme = "tor-annex:"
 
diff --git a/P2P/Annex.hs b/P2P/Annex.hs
index 56f94d2bb..9971762f5 100644
--- a/P2P/Annex.hs
+++ b/P2P/Annex.hs
@@ -11,8 +11,6 @@ module P2P.Annex
 	( RunMode(..)
 	, P2PConnection(..)
 	, runFullProto
-	, unusedPeerRemoteName
-	, linkAddress
 	) where
 
 import Annex.Common
@@ -21,16 +19,9 @@ import Annex.Transfer
 import Annex.ChangedRefs
 import P2P.Protocol
 import P2P.IO
-import P2P.Address
-import P2P.Auth
 import Logs.Location
 import Types.NumCopies
 import Utility.Metered
-import qualified Git.Command
-import qualified Annex
-import Annex.UUID
-import Git.Types (RemoteName, remoteName, remotes)
-import Config
 
 import Control.Monad.Free
 
@@ -129,17 +120,6 @@ runLocal runmode runner a = case a of
 				Left e -> return (Left (show e))
 				Right changedrefs -> runner (next changedrefs)
 		_ -> return $ Left "change notification not available"
-	AddLinkToPeer addr next -> do
-		v <- tryNonAsync $ do
-			-- Flood protection; don't let a huge number
-			-- of peer remotes be created.
-			ns <- usedPeerRemoteNames
-			if length ns > 100
-				then return $ Right False
-				else linkAddress addr [] =<< unusedPeerRemoteName
-		case v of
-			Right (Right r) -> runner (next r)
-			_ -> runner (next False)
   where
 	transfer mk k af ta = case runmode of
 		-- Update transfer logs when serving.
@@ -172,46 +152,3 @@ runLocal runmode runner a = case a of
 				liftIO $ hSeek h AbsoluteSeek o
 			b <- liftIO $ hGetContentsMetered h p'
 			runner (sender b)
-
-unusedPeerRemoteName :: Annex RemoteName
-unusedPeerRemoteName = go (1 :: Integer) =<< usedPeerRemoteNames
-  where
-	go n names = do
-		let name = "peer" ++ show n
-		if name `elem` names
-			then go (n+1) names
-			else return name
-
-usedPeerRemoteNames :: Annex [RemoteName]
-usedPeerRemoteNames = filter ("peer" `isPrefixOf`) 
-	. mapMaybe remoteName . remotes <$> Annex.gitRepo
-
-linkAddress :: P2PAddressAuth -> [P2PAddressAuth] -> RemoteName -> Annex (Either String Bool)
-linkAddress (P2PAddressAuth addr authtoken) linkbackto remotename = do
-	g <- Annex.gitRepo
-	cv <- liftIO $ tryNonAsync $ connectPeer g addr
-	case cv of
-		Left e -> return $ Left $ "Unable to connect with peer. Please check that the peer is connected to the network, and try again. ("  ++ show e ++ ")"
-		Right conn -> do
-			u <- getUUID
-			v <- liftIO $ runNetProto conn $ do
-				authresp <- P2P.Protocol.auth u authtoken
-				lbok <- forM linkbackto $ P2P.Protocol.link
-				return (authresp, lbok)
-			case v of
-				Right (Just theiruuid, lbok) -> do
-					ok <- inRepo $ Git.Command.runBool
-						[ Param "remote", Param "add"
-						, Param remotename
-						, Param (formatP2PAddress addr)
-						]
-					when ok $ do
-						storeUUIDIn (remoteConfig remotename "uuid") theiruuid
-						storeP2PRemoteAuthToken addr authtoken
-					if not ok
-						then return $ Right False
-						else if or lbok || null linkbackto
-							then return $ Right True
-							else return $ Left "Linked with peer. However, the peer was unable to link back to us, so the link is one-way."
-				Right (Nothing, _) -> return $ Left "Unable to authenticate with peer. Please check the address and try again."
-				Left e -> return $ Left $ "Unable to authenticate with peer: " ++ e
diff --git a/P2P/Protocol.hs b/P2P/Protocol.hs
index c383fa966..135409e26 100644
--- a/P2P/Protocol.hs
+++ b/P2P/Protocol.hs
@@ -14,7 +14,6 @@ module P2P.Protocol where
 import qualified Utility.SimpleProtocol as Proto
 import Types.Key
 import Types.UUID
-import P2P.Address
 import Utility.AuthToken
 import Utility.Applicative
 import Utility.PartialPrelude
@@ -50,7 +49,6 @@ data Message
 	= AUTH UUID AuthToken -- uuid of the peer that is authenticating
 	| AUTH_SUCCESS UUID -- uuid of the remote peer
 	| AUTH_FAILURE
-	| LINK P2PAddressAuth -- sending an address that the peer may link to
 	| CONNECT Service
 	| CONNECTDONE ExitCode
 	| NOTIFYCHANGE
@@ -71,9 +69,8 @@ data Message
 
 instance Proto.Sendable Message where
 	formatMessage (AUTH uuid authtoken) = ["AUTH", Proto.serialize uuid, Proto.serialize authtoken]
-	formatMessage (AUTH_SUCCESS uuid) = ["AUTH-SUCCESS", Proto.serialize uuid]
+	formatMessage (AUTH_SUCCESS uuid) = ["AUTH-SUCCESS",  Proto.serialize uuid]
 	formatMessage AUTH_FAILURE = ["AUTH-FAILURE"]
-	formatMessage (LINK addr) = ["LINK", Proto.serialize addr]
 	formatMessage (CONNECT service) = ["CONNECT", Proto.serialize service]
 	formatMessage (CONNECTDONE exitcode) = ["CONNECTDONE", Proto.serialize exitcode]
 	formatMessage NOTIFYCHANGE = ["NOTIFYCHANGE"]
@@ -95,7 +92,6 @@ instance Proto.Receivable Message where
 	parseCommand "AUTH" = Proto.parse2 AUTH
 	parseCommand "AUTH-SUCCESS" = Proto.parse1 AUTH_SUCCESS
 	parseCommand "AUTH-FAILURE" = Proto.parse0 AUTH_FAILURE
-	parseCommand "LINK" = Proto.parse1 LINK
 	parseCommand "CONNECT" = Proto.parse1 CONNECT
 	parseCommand "CONNECTDONE" = Proto.parse1 CONNECTDONE
 	parseCommand "NOTIFYCHANGE" = Proto.parse0 NOTIFYCHANGE
@@ -240,8 +236,6 @@ data LocalF c
 	-- with False.
 	| WaitRefChange (ChangedRefs -> c)
 	-- ^ Waits for one or more git refs to change and returns them.
-	| AddLinkToPeer P2PAddressAuth (Bool -> c)
-	-- ^ Adds a link to a peer using the provided address.
 	deriving (Functor)
 
 type Local = Free LocalF
@@ -261,11 +255,6 @@ auth myuuid t = do
 			net $ sendMessage (ERROR "auth failed")
 			return Nothing
 
-link :: P2PAddressAuth -> Proto Bool
-link addr = do
-	net $ sendMessage (LINK addr)
-	checkSuccess
-
 checkPresent :: Key -> Proto Bool
 checkPresent key = do
 	net $ sendMessage (CHECKPRESENT key)
@@ -365,9 +354,6 @@ serveAuth myuuid = serverLoop handler
 serveAuthed :: UUID -> Proto ()
 serveAuthed myuuid = void $ serverLoop handler
   where
-	handler (LINK addr) = do
-		sendSuccess =<< local (addLinkToPeer addr)
-		return ServerContinue
 	handler (LOCKCONTENT key) = do
 		local $ tryLockContent key $ \locked -> do
 			sendSuccess locked
diff --git a/doc/git-annex-p2p.mdwn b/doc/git-annex-p2p.mdwn
index dcfb36a3f..6c50c9dd2 100644
--- a/doc/git-annex-p2p.mdwn
+++ b/doc/git-annex-p2p.mdwn
@@ -24,26 +24,18 @@ services.
 
 * `--link`
 
-  Sets up a link with a peer over the P2P network.
+  Sets up a git remote that is accessed over a P2P network.
   
   This will prompt for an address to be entered; you should paste in the
   address that was generated by --gen-address in the remote repository.
 
-  A git remote will be created, with a name like "peer1", "peer2"
-  by default (the `--name` option can be used to specify the name).
-
-  The link is bi-directional, so the peer will also have a git
-  remote added to it, linking back to the repository where this is run.
+  Defaults to making the git remote be named "peer1", "peer2",
+  etc. This can be overridden with the `--name` option.
 
 * `--name`
 
   Specify a name to use when setting up a git remote.
 
-* `--one-way`
-
-  Use with `--link` to create a one-way link with a peer, rather than the
-  default bi-directional link.
-
 # SEE ALSO
 
 [[git-annex]](1)
diff --git a/doc/tips/peer_to_peer_network_with_tor.mdwn b/doc/tips/peer_to_peer_network_with_tor.mdwn
index 13a7f0cc7..9c97735e4 100644
--- a/doc/tips/peer_to_peer_network_with_tor.mdwn
+++ b/doc/tips/peer_to_peer_network_with_tor.mdwn
@@ -56,12 +56,12 @@ peer1 remote:
 
 	git annex sync --content peer1
 
-Any number of peers can be connected this way, within reason.
+You can also generate an address for this new peer, by running `git annex
+p2p --gen-addresses`, and link other peers to that address using `git annex
+p2p --link`. It's often useful to link peers up in both directions,
+so peer1 is a remote of peer2 and peer2 is a remote of peer1.
 
-(When the second peer links to it, the first peer also
-gets a new remote added to it, which points to the second peer.
-So, on the first peer, you can also sync with the second peer.
-The name of the that remote will be "peer1", or "peer2", etc.)
+Any number of peers can be connected this way, within reason.
 
 ## starting git-annex remotedaemon