Remove crossings hello

CHANGELOG.md

@@ -55,6 +55,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (modules/core/04-channel) [\#1232](https://github.com/cosmos/ibc-go/pull/1232) Updating params on `NewPacketId` and moving to bottom of file. 
 * (modules/core/04-channel) [\#1279](https://github.com/cosmos/ibc-go/pull/1279) Add selected channel version to MsgChanOpenInitResponse and MsgChanOpenTryResponse. Emit channel version during OpenInit/OpenTry
 * (app/29-fee) [\#1305](https://github.com/cosmos/ibc-go/pull/1305) Change version string for fee module to `ics29-1`
+* (modules/core/04-channel) [\#1317](https://github.com/cosmos/ibc-go/pull/1317)  Remove crossing hellos from ChanOpenTry
 
 ### Features
 

modules/core/04-channel/keeper/handshake.go

@@ -98,51 +98,20 @@ func (k Keeper) ChanOpenTry(
 	ctx sdk.Context,
 	order types.Order,
 	connectionHops []string,
-	portID,
-	previousChannelID string,
+	portID string,
 	portCap *capabilitytypes.Capability,
 	counterparty types.Counterparty,
 	counterpartyVersion string,
 	proofInit []byte,
 	proofHeight exported.Height,
 ) (string, *capabilitytypes.Capability, error) {
-	var (
-		previousChannel      types.Channel
-		previousChannelFound bool
-	)
-
-	channelID := previousChannelID
-
 	// connection hops only supports a single connection
 	if len(connectionHops) != 1 {
 		return "", nil, sdkerrors.Wrapf(types.ErrTooManyConnectionHops, "expected 1, got %d", len(connectionHops))
 	}
 
-	// empty channel identifier indicates continuing a previous channel handshake
-	if previousChannelID != "" {
-		// channel identifier and connection hop length checked on msg.ValidateBasic()
-		// ensure that the previous channel exists
-		previousChannel, previousChannelFound = k.GetChannel(ctx, portID, previousChannelID)
-		if !previousChannelFound {
-			return "", nil, sdkerrors.Wrapf(types.ErrInvalidChannel, "previous channel does not exist for supplied previous channelID %s", previousChannelID)
-		}
-		// previous channel must use the same fields
-		if !(previousChannel.Ordering == order &&
-			previousChannel.Counterparty.PortId == counterparty.PortId &&
-			previousChannel.Counterparty.ChannelId == "" &&
-			previousChannel.ConnectionHops[0] == connectionHops[0] && // ChanOpenInit will only set a single connection hop
-			previousChannel.Version == counterpartyVersion) {
-			return "", nil, sdkerrors.Wrap(types.ErrInvalidChannel, "channel fields mismatch previous channel fields")
-		}
-
-		if previousChannel.State != types.INIT {
-			return "", nil, sdkerrors.Wrapf(types.ErrInvalidChannelState, "previous channel state is in %s, expected INIT", previousChannel.State)
-		}
-
-	} else {
-		// generate a new channel
-		channelID = k.GenerateChannelIdentifier(ctx)
-	}
+	// generate a new channel
+	channelID := k.GenerateChannelIdentifier(ctx)
 
 	if !k.portKeeper.Authenticate(ctx, portCap, portID) {
 		return "", nil, sdkerrors.Wrapf(porttypes.ErrInvalidPort, "caller does not own port capability for port ID %s", portID)
@@ -199,20 +168,9 @@ func (k Keeper) ChanOpenTry(
 		err    error
 	)
 
-	if !previousChannelFound {
-		capKey, err = k.scopedKeeper.NewCapability(ctx, host.ChannelCapabilityPath(portID, channelID))
-		if err != nil {
-			return "", nil, sdkerrors.Wrapf(err, "could not create channel capability for port ID %s and channel ID %s", portID, channelID)
-		}
-
-	} else {
-		// capability initialized in ChanOpenInit
-		capKey, found = k.scopedKeeper.GetCapability(ctx, host.ChannelCapabilityPath(portID, channelID))
-		if !found {
-			return "", nil, sdkerrors.Wrapf(types.ErrChannelCapabilityNotFound,
-				"capability not found for existing channel, portID (%s) channelID (%s)", portID, channelID,
-			)
-		}
+	capKey, err = k.scopedKeeper.NewCapability(ctx, host.ChannelCapabilityPath(portID, channelID))
+	if err != nil {
+		return "", nil, sdkerrors.Wrapf(err, "could not create channel capability for port ID %s and channel ID %s", portID, channelID)
 	}
 
 	return channelID, capKey, nil

modules/core/04-channel/keeper/handshake_test.go

@@ -143,10 +143,9 @@ func (suite *KeeperTestSuite) TestChanOpenInit() {
 // ChanOpenTry can succeed.
 func (suite *KeeperTestSuite) TestChanOpenTry() {
 	var (
-		path              *ibctesting.Path
-		previousChannelID string
-		portCap           *capabilitytypes.Capability
-		heightDiff        uint64
+		path       *ibctesting.Path
+		portCap    *capabilitytypes.Capability
+		heightDiff uint64
 	)
 
 	testCases := []testCase{
@@ -164,22 +163,8 @@ func (suite *KeeperTestSuite) TestChanOpenTry() {
 			err := suite.coordinator.ChanOpenInitOnBothChains(path)
 			suite.Require().NoError(err)
 
-			previousChannelID = path.EndpointB.ChannelID
 			portCap = suite.chainB.GetPortCapability(ibctesting.MockPort)
 		}, true},
-		{"previous channel with invalid version, crossing hello", func() {
-			suite.coordinator.SetupConnections(path)
-			path.SetChannelOrdered()
-
-			// modify channel version
-			path.EndpointA.ChannelConfig.Version = "invalid version"
-
-			err := suite.coordinator.ChanOpenInitOnBothChains(path)
-			suite.Require().NoError(err)
-
-			previousChannelID = path.EndpointB.ChannelID
-			portCap = suite.chainB.GetPortCapability(ibctesting.MockPort)
-		}, false},
 		{"previous channel with invalid state", func() {
 			suite.coordinator.SetupConnections(path)
 
@@ -268,7 +253,6 @@ func (suite *KeeperTestSuite) TestChanOpenTry() {
 		suite.Run(fmt.Sprintf("Case %s", tc.msg), func() {
 			suite.SetupTest() // reset
 			heightDiff = 0    // must be explicitly changed in malleate
-			previousChannelID = ""
 			path = ibctesting.NewPath(suite.chainA, suite.chainB)
 
 			tc.malleate()
@@ -286,7 +270,7 @@ func (suite *KeeperTestSuite) TestChanOpenTry() {
 
 			channelID, cap, err := suite.chainB.App.GetIBCKeeper().ChannelKeeper.ChanOpenTry(
 				suite.chainB.GetContext(), types.ORDERED, []string{path.EndpointB.ConnectionID},
-				path.EndpointB.ChannelConfig.PortID, previousChannelID, portCap, counterparty, path.EndpointA.ChannelConfig.Version,
+				path.EndpointB.ChannelConfig.PortID, portCap, counterparty, path.EndpointA.ChannelConfig.Version,
 				proof, malleateHeight(proofHeight, heightDiff),
 			)
 

modules/core/keeper/msg_server.go

@@ -217,7 +217,7 @@ func (k Keeper) ChannelOpenTry(goCtx context.Context, msg *channeltypes.MsgChann
 	}
 
 	// Perform 04-channel verification
-	channelID, cap, err := k.ChannelKeeper.ChanOpenTry(ctx, msg.Channel.Ordering, msg.Channel.ConnectionHops, msg.PortId, msg.PreviousChannelId,
+	channelID, cap, err := k.ChannelKeeper.ChanOpenTry(ctx, msg.Channel.Ordering, msg.Channel.ConnectionHops, msg.PortId,
 		portCap, msg.Channel.Counterparty, msg.CounterpartyVersion, msg.ProofInit, msg.ProofHeight,
 	)
 	if err != nil {

proto/ibc/core/channel/v1/tx.proto

@@ -81,6 +81,7 @@ message MsgChannelOpenTry {
   string port_id = 1 [(gogoproto.moretags) = "yaml:\"port_id\""];
   // in the case of crossing hello's, when both chains call OpenInit, we need
   // the channel identifier of the previous channel in state INIT
+  // this field has been deprecated and will be ignored by core IBC because now we don't need to protect against crossing hellos anymore.
   string previous_channel_id = 2 [(gogoproto.moretags) = "yaml:\"previous_channel_id\""];
   // NOTE: the version field within the channel has been deprecated. Its value will be ignored by core IBC.
   Channel                   channel              = 3 [(gogoproto.nullable) = false];