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

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Both the local and remote git repositories get remotes added
pointing at one-another.

Makes pairing twice as easy!

Security: The new LINK command in the protocol can be sent repeatedly,
but only by a peer who has authenticated with us. So, it's entirely safe to
add a link back to that peer, or to some other peer it knows about.
Anything we receive over such a link, the peer could send us over the
current connection.

There is some risk of being flooded with LINKs, and adding too many
remotes. To guard against that, there's a hard cap on the number of remotes
that can be set up this way. This will only be a problem if setting up
large p2p networks that have exceptional interconnectedness.

A new, dedicated authtoken is created when sending LINK.

This also allows, in theory, using a p2p network like tor, to learn about
links on other networks, like telehash.

This commit was sponsored by Bruno BEAUFILS on Patreon.
This commit is contained in:
Joey Hess 2016-12-16 16:32:29 -04:00
commit 3037feb1bf
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GPG key ID: C910D9222512E3C7
7 changed files with 105 additions and 46 deletions
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16
P2P/Protocol.hs
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@ -14,6 +14,7 @@ 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
@ -49,6 +50,7 @@ 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
@ -69,8 +71,9 @@ 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"]
@ -92,6 +95,7 @@ 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
@ -236,6 +240,8 @@ 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
@ -255,6 +261,11 @@ 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)
@ -354,6 +365,9 @@ 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