Add nil checks on the controller module for underlying app

CHANGELOG.md

@@ -88,6 +88,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (client) [\#724](https://github.com/cosmos/ibc-go/pull/724) `IsRevisionFormat` and `IsClientIDFormat` have been updated to disallow newlines before the dash used to separate the chainID and revision number, and the client type and client sequence.
 * (02-client/cli) [\#897](https://github.com/cosmos/ibc-go/pull/897) Remove `GetClientID()` from `Misbehaviour` interface. Submit client misbehaviour cli command requires an explicit client id now.
 * (06-solomachine) [\#1972](https://github.com/cosmos/ibc-go/pull/1972) Solo machine implementation of `ZeroCustomFields` fn now panics as the fn is only used for upgrades which solo machine does not support. 
+* (apps/27-interchain-accounts) [\#2102](https://github.com/cosmos/ibc-go/pull/2102) ICS27 controller middleware now supports a nil underlying application. This allows chains to make use of interchain accounts with existing auth mechanisms such as x/group and x/gov.
 
 ### Features
 

modules/apps/27-interchain-accounts/controller/ibc_middleware.go

@@ -58,8 +58,10 @@ func (im IBCMiddleware) OnChanOpenInit(
 	// call underlying app's OnChanOpenInit callback with the passed in version
 	// the version returned is discarded as the ica-auth module does not have permission to edit the version string.
 	// ics27 will always return the version string containing the Metadata struct which is created during the `RegisterInterchainAccount` call.
-	if _, err := im.app.OnChanOpenInit(ctx, order, connectionHops, portID, channelID, chanCap, counterparty, version); err != nil {
-		return "", err
+	if im.app != nil {
+		if _, err := im.app.OnChanOpenInit(ctx, order, connectionHops, portID, channelID, chanCap, counterparty, version); err != nil {
+			return "", err
+		}
 	}
 
 	return version, nil
@@ -101,7 +103,11 @@ func (im IBCMiddleware) OnChanOpenAck(
 	}
 
 	// call underlying app's OnChanOpenAck callback with the counterparty app version.
-	return im.app.OnChanOpenAck(ctx, portID, channelID, counterpartyChannelID, counterpartyVersion)
+	if im.app != nil {
+		return im.app.OnChanOpenAck(ctx, portID, channelID, counterpartyChannelID, counterpartyVersion)
+	}
+
+	return nil
 }
 
 // OnChanOpenAck implements the IBCMiddleware interface
@@ -156,7 +162,11 @@ func (im IBCMiddleware) OnAcknowledgementPacket(
 	}
 
 	// call underlying app's OnAcknowledgementPacket callback.
-	return im.app.OnAcknowledgementPacket(ctx, packet, acknowledgement, relayer)
+	if im.app != nil {
+		return im.app.OnAcknowledgementPacket(ctx, packet, acknowledgement, relayer)
+	}
+
+	return nil
 }
 
 // OnTimeoutPacket implements the IBCMiddleware interface
@@ -173,7 +183,11 @@ func (im IBCMiddleware) OnTimeoutPacket(
 		return err
 	}
 
-	return im.app.OnTimeoutPacket(ctx, packet, relayer)
+	if im.app != nil {
+		return im.app.OnTimeoutPacket(ctx, packet, relayer)
+	}
+
+	return nil
 }
 
 // SendPacket implements the ICS4 Wrapper interface

modules/apps/27-interchain-accounts/controller/ibc_middleware_test.go

@@ -9,6 +9,7 @@ import (
 	"github.com/stretchr/testify/suite"
 	"github.com/tendermint/tendermint/crypto"
 
+	"github.com/cosmos/ibc-go/v5/modules/apps/27-interchain-accounts/controller"
 	"github.com/cosmos/ibc-go/v5/modules/apps/27-interchain-accounts/controller/types"
 	icatypes "github.com/cosmos/ibc-go/v5/modules/apps/27-interchain-accounts/types"
 	fee "github.com/cosmos/ibc-go/v5/modules/apps/29-fee"
@@ -120,7 +121,10 @@ func SetupICAPath(path *ibctesting.Path, owner string) error {
 }
 
 func (suite *InterchainAccountsTestSuite) TestOnChanOpenInit() {
-	var channel *channeltypes.Channel
+	var (
+		channel  *channeltypes.Channel
+		isNilApp bool
+	)
 
 	testCases := []struct {
 		name     string
@@ -162,13 +166,19 @@ func (suite *InterchainAccountsTestSuite) TestOnChanOpenInit() {
 				}
 			}, false,
 		},
+		{
+			"nil underlying app", func() {
+				isNilApp = true
+			}, true,
+		},
 	}
 
 	for _, tc := range testCases {
 		tc := tc
 
 		suite.Run(tc.name, func() {
 			suite.SetupTest() // reset
+			isNilApp = false
 
 			path := NewICAPath(suite.chainA, suite.chainB)
 			suite.coordinator.SetupConnections(path)
@@ -207,6 +217,10 @@ func (suite *InterchainAccountsTestSuite) TestOnChanOpenInit() {
 			cbs, ok := suite.chainA.App.GetIBCKeeper().Router.GetRoute(module)
 			suite.Require().True(ok)
 
+			if isNilApp {
+				cbs = controller.NewIBCMiddleware(nil, suite.chainA.GetSimApp().ICAControllerKeeper)
+			}
+
 			version, err := cbs.OnChanOpenInit(suite.chainA.GetContext(), channel.Ordering, channel.GetConnectionHops(),
 				path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, chanCap, channel.Counterparty, channel.GetVersion(),
 			)
@@ -271,7 +285,10 @@ func (suite *InterchainAccountsTestSuite) TestChanOpenTry() {
 }
 
 func (suite *InterchainAccountsTestSuite) TestOnChanOpenAck() {
-	var path *ibctesting.Path
+	var (
+		path     *ibctesting.Path
+		isNilApp bool
+	)
 
 	testCases := []struct {
 		name     string
@@ -300,13 +317,19 @@ func (suite *InterchainAccountsTestSuite) TestOnChanOpenAck() {
 				}
 			}, false,
 		},
+		{
+			"nil underlying app", func() {
+				isNilApp = true
+			}, true,
+		},
 	}
 
 	for _, tc := range testCases {
 		tc := tc
 
 		suite.Run(tc.name, func() {
 			suite.SetupTest() // reset
+			isNilApp = false
 
 			path = NewICAPath(suite.chainA, suite.chainB)
 			suite.coordinator.SetupConnections(path)
@@ -327,6 +350,10 @@ func (suite *InterchainAccountsTestSuite) TestOnChanOpenAck() {
 
 			err = cbs.OnChanOpenAck(suite.chainA.GetContext(), path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, path.EndpointB.ChannelID, path.EndpointB.ChannelConfig.Version)
 
+			if isNilApp {
+				cbs = controller.NewIBCMiddleware(nil, suite.chainA.GetSimApp().ICAControllerKeeper)
+			}
+
 			if tc.expPass {
 				suite.Require().NoError(err)
 			} else {
@@ -497,7 +524,10 @@ func (suite *InterchainAccountsTestSuite) TestOnRecvPacket() {
 }
 
 func (suite *InterchainAccountsTestSuite) TestOnAcknowledgementPacket() {
-	var path *ibctesting.Path
+	var (
+		path     *ibctesting.Path
+		isNilApp bool
+	)
 
 	testCases := []struct {
 		msg      string
@@ -523,11 +553,17 @@ func (suite *InterchainAccountsTestSuite) TestOnAcknowledgementPacket() {
 				}
 			}, false,
 		},
+		{
+			"nil underlying app", func() {
+				isNilApp = true
+			}, true,
+		},
 	}
 
 	for _, tc := range testCases {
 		suite.Run(tc.msg, func() {
 			suite.SetupTest() // reset
+			isNilApp = false
 
 			path = NewICAPath(suite.chainA, suite.chainB)
 			suite.coordinator.SetupConnections(path)
@@ -554,6 +590,10 @@ func (suite *InterchainAccountsTestSuite) TestOnAcknowledgementPacket() {
 			cbs, ok := suite.chainA.App.GetIBCKeeper().Router.GetRoute(module)
 			suite.Require().True(ok)
 
+			if isNilApp {
+				cbs = controller.NewIBCMiddleware(nil, suite.chainA.GetSimApp().ICAControllerKeeper)
+			}
+
 			err = cbs.OnAcknowledgementPacket(suite.chainA.GetContext(), packet, []byte("ack"), nil)
 
 			if tc.expPass {
@@ -566,7 +606,10 @@ func (suite *InterchainAccountsTestSuite) TestOnAcknowledgementPacket() {
 }
 
 func (suite *InterchainAccountsTestSuite) TestOnTimeoutPacket() {
-	var path *ibctesting.Path
+	var (
+		path     *ibctesting.Path
+		isNilApp bool
+	)
 
 	testCases := []struct {
 		msg      string
@@ -592,11 +635,17 @@ func (suite *InterchainAccountsTestSuite) TestOnTimeoutPacket() {
 				}
 			}, false,
 		},
+		{
+			"nil underlying app", func() {
+				isNilApp = true
+			}, true,
+		},
 	}
 
 	for _, tc := range testCases {
 		suite.Run(tc.msg, func() {
 			suite.SetupTest() // reset
+			isNilApp = false
 
 			path = NewICAPath(suite.chainA, suite.chainB)
 			suite.coordinator.SetupConnections(path)
@@ -623,6 +672,10 @@ func (suite *InterchainAccountsTestSuite) TestOnTimeoutPacket() {
 			cbs, ok := suite.chainA.App.GetIBCKeeper().Router.GetRoute(module)
 			suite.Require().True(ok)
 
+			if isNilApp {
+				cbs = controller.NewIBCMiddleware(nil, suite.chainA.GetSimApp().ICAControllerKeeper)
+			}
+
 			err = cbs.OnTimeoutPacket(suite.chainA.GetContext(), packet, nil)
 
 			if tc.expPass {