clean up protocol version for proxying

The proxy always checks the protocol version of a remote before talking
to it in a version-specific way, so the protocol version in the ProxyParams
is the client's protocol version. The remote will always be at the same or
an older protocol version than the client.

Note that in relayDATAFinish, when the client is at protocol version 0,
the remote must thus be as well, and that's why its version is not
checked in the case for that.

With that clarified, it's evident that, in P2P.Http.State, there's no
need to look at the proxied remote's protocol version at all.

Annex/Cluster.hs

@@ -51,9 +51,8 @@ proxyCluster clusteruuid proxydone servermode clientside protoerrhandler = do
 		-- known at this point, and would be too expensive to
 		-- determine. Instead, pick the newest protocol version
 		-- that we and the client both speak. The proxy code
-		-- checks protocol versions when operating on multiple
-		-- nodes, and allows nodes to have different protocol
-		-- versions.
+		-- checks protocol versions of remotes, so nodes can
+		-- have different protocol versions.
 		let protocolversion = min maxProtocolVersion clientmaxversion
 		sendClientProtocolVersion clientside othermsg protocolversion
 			(getclientbypass protocolversion) (protoerrhandler noop)
@@ -76,7 +75,7 @@ proxyCluster clusteruuid proxydone servermode clientside protoerrhandler = do
 			, proxyUUID = fromClusterUUID clusteruuid
 			, proxySelector = selectnode
 			, proxyConcurrencyConfig = concurrencyconfig
-			, proxyProtocolVersion = protocolversion
+			, proxyClientProtocolVersion = protocolversion
 			}
 		proxy proxydone proxyparams othermsg
 			(protoerrhandler closenodes)

Command/P2PStdIO.hs

@@ -84,7 +84,7 @@ performProxy clientuuid servermode r = do
 			, proxyUUID = Remote.uuid r
 			, proxySelector = singleProxySelector remoteside
 			, proxyConcurrencyConfig = concurrencyconfig
-			, proxyProtocolVersion = protocolversion
+			, proxyClientProtocolVersion = protocolversion
 			}
 		let runproxy othermsg' = proxy closer proxyparams 
 			othermsg' errhandler

P2P/Http/State.hs

@@ -346,9 +346,8 @@ proxyConnection relv connparams workerpool proxyconn = do
 		inAnnexWorker' workerpool $ do
 			proxystate <- liftIO Proxy.mkProxyState
 			concurrencyconfig <- Proxy.noConcurrencyConfig
-			-- TODO run remote protocol to get its version and
-			-- take minimum of that and connectionProtocolVersion
-			let protocolversion = connectionProtocolVersion connparams
+			let protocolversion = min remoteprotocolversion $
+				connectionProtocolVersion connparams
 			let proxyparams = Proxy.ProxyParams
 				{ Proxy.proxyMethods = mkProxyMethods
 				, Proxy.proxyState = proxystate
@@ -358,7 +357,7 @@ proxyConnection relv connparams workerpool proxyconn = do
 				, Proxy.proxySelector = Proxy.singleProxySelector $
 					proxyConnectionRemoteSide proxyconn
 				, Proxy.proxyConcurrencyConfig = concurrencyconfig
-				, Proxy.proxyProtocolVersion = protocolversion
+				, Proxy.proxyClientProtocolVersion = protocolversion
 				}
 			let proxy mrequestmessage = case mrequestmessage of
 				Just requestmessage -> do
@@ -516,8 +515,8 @@ openProxyConnectionToRemote
 	-> [UUID]
 	-> Remote
 	-> IO (Either SomeException ProxyConnection)
-openProxyConnectionToRemote workerpool protoversion bypass remote =
-	inAnnexWorker' workerpool (proxyRemoteSide protoversion bypass' remote) >>= \case
+openProxyConnectionToRemote workerpool clientmaxversion bypass remote =
+	inAnnexWorker' workerpool (proxyRemoteSide clientmaxversion bypass' remote) >>= \case
 		Left ex -> return (Left ex)
 		Right remoteside -> return $ Right $
 			ProxyConnection (Remote.uuid remote) remoteside

P2P/Proxy.hs

@@ -208,10 +208,9 @@ data ProxyParams = ProxyParams
 	, proxyUUID :: UUID
 	, proxySelector :: ProxySelector
 	, proxyConcurrencyConfig :: ConcurrencyConfig
-	, proxyProtocolVersion :: ProtocolVersion
-	-- ^ Protocol version being spoken between the proxy and the
-	-- client. When there are multiple remotes, some may speak an
-	-- earlier version.
+	, proxyClientProtocolVersion :: ProtocolVersion
+	-- ^ The remote(s) may speak an earlier version, or the same
+	-- version, but not a later version.
 	}
 
 {- Proxy between the client and the remote. This picks up after
@@ -452,7 +451,7 @@ proxyRequest proxydone proxyparams requestcomplete requestmessage protoerrhandle
 		protoerrhandler requestcomplete $
 			client $ net $ sendMessage $
 				let nonplussed = all (== proxyUUID proxyparams) us 
-					|| proxyProtocolVersion proxyparams < ProtocolVersion 2
+					|| proxyClientProtocolVersion proxyparams < ProtocolVersion 2
 				in if all (maybe False (fst . fst)) v'
 					then if nonplussed
 						then SUCCESS
@@ -496,7 +495,7 @@ proxyRequest proxydone proxyparams requestcomplete requestmessage protoerrhandle
 			relayDATAFinish (runRemoteSide remoteside) client $
 				relayonemessage client (runRemoteSide remoteside) $
 					const requestcomplete
-	
+
 	relayPUT remoteside k len = relayDATAStart (runRemoteSide remoteside) $
 		relayDATACore len client (runRemoteSide remoteside) $
 			relayDATAFinish client (runRemoteSide remoteside) $
@@ -536,7 +535,7 @@ proxyRequest proxydone proxyparams requestcomplete requestmessage protoerrhandle
 			_ -> False
 		l <- forMC (proxyConcurrencyConfig proxyparams) remotesides initiate
 		if all alreadyhave l
-			then if proxyProtocolVersion proxyparams < ProtocolVersion 2
+			then if proxyClientProtocolVersion proxyparams < ProtocolVersion 2
 				then protoerrhandler requestcomplete $
 					client $ net $ sendMessage ALREADY_HAVE
 				else protoerrhandler requestcomplete $
@@ -621,7 +620,7 @@ proxyRequest proxydone proxyparams requestcomplete requestmessage protoerrhandle
 		| otherwise = relayonemessage x y (\_ () -> sendsuccessfailure)
 
 	relayDATAFinishMulti k rs
-		| proxyProtocolVersion proxyparams == ProtocolVersion 0 = 
+		| proxyProtocolVersion proxyparams == ProtocolVersion 0 =
 			finish $ net receiveMessage
 		| otherwise =
 			flip protoerrhandler (client $ net $ receiveMessage) $
@@ -646,7 +645,7 @@ proxyRequest proxydone proxyparams requestcomplete requestmessage protoerrhandle
 					case concat (catMaybes storeduuids) of
 						[] -> FAILURE
 						us
-							| proxyProtocolVersion proxyparams < ProtocolVersion 2 -> SUCCESS
+							| proxyClientProtocolVersion proxyparams < ProtocolVersion 2 -> SUCCESS
 							| otherwise -> SUCCESS_PLUS us
 
 	-- The associated file received from the P2P protocol

doc/todo/git-annex_proxies.mdwn

@@ -30,9 +30,6 @@ Planned schedule of work:
 
 * http server proxying hangs on git-annex copy --to it
 
-* http server proxying needs to get the version negotiated with the proxied
-  remote and feed that into the proxy function.
-
 * test http server proxying with special remotes
 
 * http server proxying needs to reuse connections to special remotes,