Allow Explicit Server Resyncing

event/common.go

@@ -230,6 +230,10 @@ const (
 	// Onion: the local onion we attempt to check
 	NetworkStatus = Type("NetworkError")
 
+	// Notify the UI that a Server has been added
+	// Onion = Server Onion
+	ServerCreated = Type("ServerAdded")
+
 	// For debugging. Allows test to emit a Syn and get a response Ack(eventID) when the subsystem is done processing a queue
 	Syn = Type("Syn")
 	Ack = Type("Ack")

go.mod

@@ -3,7 +3,7 @@ module cwtch.im/cwtch
 go 1.14
 
 require (
-	git.openprivacy.ca/cwtch.im/tapir v0.4.1
+	git.openprivacy.ca/cwtch.im/tapir v0.4.2
 	git.openprivacy.ca/openprivacy/connectivity v1.4.3
 	git.openprivacy.ca/openprivacy/log v1.0.2
 	github.com/gtank/ristretto255 v0.1.2

go.sum

@@ -12,6 +12,8 @@ git.openprivacy.ca/cwtch.im/tapir v0.4.0 h1:clG8uORt0NKEhT4P+Dpw1pzyUuYzYBMevGqn
 git.openprivacy.ca/cwtch.im/tapir v0.4.0/go.mod h1:eH6dZxXrhW0C4KZX18ksUa6XJCrEvtg8cJJ/Fy6gv+E=
 git.openprivacy.ca/cwtch.im/tapir v0.4.1 h1:9LMpQX41IzecNNlRc1FZKXHg6wlFss679tFsa3vzb3Y=
 git.openprivacy.ca/cwtch.im/tapir v0.4.1/go.mod h1:eH6dZxXrhW0C4KZX18ksUa6XJCrEvtg8cJJ/Fy6gv+E=
+git.openprivacy.ca/cwtch.im/tapir v0.4.2 h1:bxMWZnVJXX4dqqOFS7ELW4iFkVL4GS8wiRkjRv5rJe8=
+git.openprivacy.ca/cwtch.im/tapir v0.4.2/go.mod h1:eH6dZxXrhW0C4KZX18ksUa6XJCrEvtg8cJJ/Fy6gv+E=
 git.openprivacy.ca/openprivacy/bine v0.0.4 h1:CO7EkGyz+jegZ4ap8g5NWRuDHA/56KKvGySR6OBPW+c=
 git.openprivacy.ca/openprivacy/bine v0.0.4/go.mod h1:13ZqhKyqakDsN/ZkQkIGNULsmLyqtXc46XBcnuXm/mU=
 git.openprivacy.ca/openprivacy/connectivity v1.4.0 h1:c7AANUCrlA4hIqXxIGDOWMtSe8CpDleD1877PShScbM=

peer/cwtch_peer.go

@@ -122,6 +122,7 @@ type ModifyGroups interface {
 // ModifyServers provides write-only access to servers
 type ModifyServers interface {
 	AddServer(string) error
+	ResyncServer(onion string) error
 }
 
 // SendMessages enables a caller to sender messages to a contact
@@ -326,6 +327,8 @@ func (cp *cwtchPeer) AddServer(serverSpecification string) error {
 			cp.mutex.Unlock()
 
 			pd, _ := json.Marshal(pp)
+
+			// Sync the Storage Engine
 			cp.eventBus.Publish(event.NewEvent(event.PeerCreated, map[event.Field]string{
 				event.Data:       string(pd),
 				event.RemotePeer: onion,
@@ -473,6 +476,20 @@ func (cp *cwtchPeer) JoinServer(onion string) error {
 	return errors.New("no keys found for server connection")
 }
 
+// ResyncServer completely tears down and resyncs a new server connection with the given onion address
+func (cp *cwtchPeer) ResyncServer(onion string) error {
+	if cp.GetContact(onion) != nil {
+		tokenY, yExists := cp.GetContact(onion).GetAttribute(string(model.KeyTypePrivacyPass))
+		tokenOnion, onionExists := cp.GetContact(onion).GetAttribute(string(model.KeyTypeTokenOnion))
+		if yExists && onionExists {
+			signature := base64.StdEncoding.EncodeToString([]byte{})
+			cp.eventBus.Publish(event.NewEvent(event.JoinServer, map[event.Field]string{event.GroupServer: onion, event.ServerTokenY: tokenY, event.ServerTokenOnion: tokenOnion, event.Signature: signature}))
+			return nil
+		}
+	}
+	return errors.New("no keys found for server connection")
+}
+
 // SendMessageToGroupTracked attempts to sent the given message to the given group id.
 // It returns the signature of the message which can be used to identify it in any UX layer.
 func (cp *cwtchPeer) SendMessageToGroupTracked(groupid string, message string) (string, error) {
@@ -684,7 +701,14 @@ func (cp *cwtchPeer) eventHandler() {
 
 			ciphertext, _ := base64.StdEncoding.DecodeString(ev.Data[event.Ciphertext])
 			signature, _ := base64.StdEncoding.DecodeString(ev.Data[event.Signature])
+
+			// SECURITY NOTE: A malicious server could insert posts such that everyone always has a different lastKnownSignature
+			// However the server can always replace **all** messages in an attempt to track users
+			// This is mitigated somewhat by resync events which do wipe things entire.
+			// The security of cwtch groups are also not dependent on the servers inability to uniquely tag connections (as long as
+			// it learns nothing else about each connection).
 			cp.SetContactAttribute(ev.Data[event.GroupServer], lastKnownSignature, ev.Data[event.Signature])
+
 			cp.mutex.Lock()
 			ok, groupID, message, seen := cp.Profile.AttemptDecryption(ciphertext, signature)
 			cp.mutex.Unlock()

protocol/connections/engine.go

@@ -136,12 +136,7 @@ func (e *engine) eventHandler() {
 			}
 			go e.peerWithTokenServer(ev.Data[event.GroupServer], ev.Data[event.ServerTokenOnion], ev.Data[event.ServerTokenY], signature)
 		case event.LeaveServer:
-			es, ok := e.ephemeralServices.Load(ev.Data[event.GroupServer])
-			if ok {
-				ephemeralService := es.(tapir.Service)
-				ephemeralService.Shutdown()
-				e.ephemeralServices.Delete(ev.Data[event.GroupServer])
-			}
+			e.leaveServer(ev.Data[event.GroupServer])
 		case event.DeleteContact:
 			onion := ev.Data[event.RemotePeer]
 			// We remove this peer from out blocklist which will prevent them from contacting us if we have "block unknown peers" turned on.
@@ -279,8 +274,14 @@ func (e *engine) peerWithTokenServer(onion string, tokenServerOnion string, toke
 	if exists {
 		connection := service.(*tor.BaseOnionService)
 		if conn, err := connection.GetConnection(onion); err == nil {
-			if conn.IsClosed() == false {
+			// We are already peered and synced so return...
+			// This will only not-trigger it lastKnownSignature has been wiped, which only happens when ResyncServer is called
+			// in CwtchPeer.
+			if conn.IsClosed() == false && len(lastKnownSignature) != 0 {
 				return
+			} else {
+				// Otherwise...we are going to rebuild the connection(which will result in a bandwidth heavy resync)...
+				e.leaveServer(onion)
 			}
 		}
 		// Otherwise...let's reconnect
@@ -508,3 +509,12 @@ func (e *engine) handlePeerRetVal(hostname string, getValData, retValData []byte
 
 	e.eventManager.Publish(event.NewEventList(event.NewRetValMessageFromPeer, event.RemotePeer, hostname, event.Scope, getVal.Scope, event.Path, getVal.Path, event.Exists, strconv.FormatBool(retVal.Exists), event.Data, retVal.Val))
 }
+
+func (e *engine) leaveServer(server string) {
+	es, ok := e.ephemeralServices.Load(server)
+	if ok {
+		ephemeralService := es.(tapir.Service)
+		ephemeralService.Shutdown()
+		e.ephemeralServices.Delete(server)
+	}
+}