chore: add channel client state rpc

modules/core/04-channel/v2/client/cli/cli.go

@@ -20,6 +20,7 @@ func GetQueryCmd() *cobra.Command {
 
 	queryCmd.AddCommand(
 		getCmdQueryChannel(),
+		getCmdQueryChannelClientState(),
 		getCmdQueryNextSequenceSend(),
 		getCmdQueryPacketCommitment(),
 		getCmdQueryPacketCommitments(),

modules/core/04-channel/v2/client/cli/query.go

@@ -49,6 +49,37 @@ func getCmdQueryChannel() *cobra.Command {
 	return cmd
 }
 
+// getCmdQueryChannelClientState defines the command to query the channel client state for the given channel ID.
+func getCmdQueryChannelClientState() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:     "client-state [channel-id]",
+		Short:   "Query the client state associated with a channel.",
+		Long:    "Query the client state associated with a channel for the provided channel ID.",
+		Example: fmt.Sprintf("%s query %s %s client-state [channel-id]", version.AppName, exported.ModuleName, types.SubModuleName),
+		Args:    cobra.ExactArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			clientCtx, err := client.GetClientQueryContext(cmd)
+			if err != nil {
+				return err
+			}
+
+			channelID := args[0]
+			queryClient := types.NewQueryClient(clientCtx)
+
+			res, err := queryClient.ChannelClientState(cmd.Context(), types.NewQueryChannelClientStateRequest(channelID))
+			if err != nil {
+				return err
+			}
+
+			return clientCtx.PrintProto(res)
+		},
+	}
+
+	flags.AddQueryFlagsToCmd(cmd)
+
+	return cmd
+}
+
 // getCmdQueryNextSequenceSend defines the command to query a next send sequence for a given channel
 func getCmdQueryNextSequenceSend() *cobra.Command {
 	cmd := &cobra.Command{

modules/core/04-channel/v2/keeper/grpc_query.go

@@ -51,6 +51,32 @@ func (q *queryServer) Channel(ctx context.Context, req *types.QueryChannelReques
 	return types.NewQueryChannelResponse(channel), nil
 }
 
+// ChannelClientState implements the Query/ChannelClientState gRPC method
+func (q *queryServer) ChannelClientState(ctx context.Context, req *types.QueryChannelClientStateRequest) (*types.QueryChannelClientStateResponse, error) {
+	if req == nil {
+		return nil, status.Error(codes.InvalidArgument, "empty request")
+	}
+
+	if err := host.ChannelIdentifierValidator(req.ChannelId); err != nil {
+		return nil, status.Error(codes.InvalidArgument, err.Error())
+	}
+
+	channel, found := q.GetChannel(ctx, req.ChannelId)
+	if !found {
+		return nil, status.Error(codes.NotFound, errorsmod.Wrapf(types.ErrChannelNotFound, "channel-id: %s", req.ChannelId).Error())
+	}
+
+	clientState, found := q.ClientKeeper.GetClientState(ctx, channel.ClientId)
+	if !found {
+		return nil, status.Error(codes.NotFound, errorsmod.Wrapf(clienttypes.ErrClientNotFound, "client-id: %s", channel.ClientId).Error())
+	}
+
+	identifiedClientState := clienttypes.NewIdentifiedClientState(channel.ClientId, clientState)
+	res := types.NewQueryChannelClientStateResponse(identifiedClientState, nil, clienttypes.GetSelfHeight(ctx))
+
+	return res, nil
+}
+
 // NextSequenceSend implements the Query/NextSequenceSend gRPC method
 func (q *queryServer) NextSequenceSend(ctx context.Context, req *types.QueryNextSequenceSendRequest) (*types.QueryNextSequenceSendResponse, error) {
 	if req == nil {

modules/core/04-channel/v2/keeper/grpc_query_test.go

@@ -8,6 +8,7 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/types/query"
 
+	clienttypes "github.com/cosmos/ibc-go/v9/modules/core/02-client/types"
 	"github.com/cosmos/ibc-go/v9/modules/core/04-channel/v2/keeper"
 	"github.com/cosmos/ibc-go/v9/modules/core/04-channel/v2/types"
 	commitmenttypes "github.com/cosmos/ibc-go/v9/modules/core/23-commitment/types"
@@ -89,6 +90,106 @@ func (suite *KeeperTestSuite) TestQueryChannel() {
 	}
 }
 
+func (suite *KeeperTestSuite) TestQueryChannelClientState() {
+	var (
+		req                      *types.QueryChannelClientStateRequest
+		expIdentifiedClientState clienttypes.IdentifiedClientState
+	)
+
+	testCases := []struct {
+		msg      string
+		malleate func()
+		expError error
+	}{
+		{
+			"success",
+			func() {
+				path := ibctesting.NewPath(suite.chainA, suite.chainB)
+				path.SetupV2()
+
+				expClientState := suite.chainA.GetClientState(path.EndpointA.ClientID)
+				expIdentifiedClientState = clienttypes.NewIdentifiedClientState(path.EndpointA.ClientID, expClientState)
+
+				req = &types.QueryChannelClientStateRequest{
+					ChannelId: path.EndpointA.ChannelID,
+				}
+			},
+			nil,
+		},
+		{
+			"empty request",
+			func() {
+				req = nil
+			},
+			status.Error(codes.InvalidArgument, "empty request"),
+		},
+		{
+			"invalid channel ID",
+			func() {
+				req = &types.QueryChannelClientStateRequest{
+					ChannelId: "",
+				}
+			},
+			status.Error(codes.InvalidArgument, "identifier cannot be blank: invalid identifier"),
+		},
+		{
+			"channel not found",
+			func() {
+				req = &types.QueryChannelClientStateRequest{
+					ChannelId: "test-channel-id",
+				}
+			},
+			status.Error(codes.NotFound, fmt.Sprintf("channel-id: %s: channel not found", "test-channel-id")),
+		},
+		{
+			"client state not found",
+			func() {
+				path := ibctesting.NewPath(suite.chainA, suite.chainB)
+				path.SetupV2()
+
+				channel, found := path.EndpointA.Chain.App.GetIBCKeeper().ChannelKeeperV2.GetChannel(suite.chainA.GetContext(), path.EndpointA.ChannelID)
+				suite.Require().True(found)
+				channel.ClientId = ibctesting.SecondClientID
+
+				path.EndpointA.Chain.App.GetIBCKeeper().ChannelKeeperV2.SetChannel(suite.chainA.GetContext(), path.EndpointA.ChannelID, channel)
+
+				req = &types.QueryChannelClientStateRequest{
+					ChannelId: path.EndpointA.ChannelID,
+				}
+			},
+			status.Error(codes.NotFound, fmt.Sprintf("client-id: %s: light client not found", ibctesting.SecondClientID)),
+		},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+
+		suite.Run(fmt.Sprintf("Case %s", tc.msg), func() {
+			suite.SetupTest() // reset
+
+			tc.malleate()
+			ctx := suite.chainA.GetContext()
+
+			queryServer := keeper.NewQueryServer(suite.chainA.App.GetIBCKeeper().ChannelKeeperV2)
+			res, err := queryServer.ChannelClientState(ctx, req)
+
+			expPass := tc.expError == nil
+			if expPass {
+				suite.Require().NoError(err)
+				suite.Require().NotNil(res)
+				suite.Require().Equal(&expIdentifiedClientState, res.IdentifiedClientState)
+
+				// ensure UnpackInterfaces is defined
+				cachedValue := res.IdentifiedClientState.ClientState.GetCachedValue()
+				suite.Require().NotNil(cachedValue)
+			} else {
+				suite.Require().ErrorIs(err, tc.expError)
+				suite.Require().Nil(res)
+			}
+		})
+	}
+}
+
 func (suite *KeeperTestSuite) TestQueryPacketCommitment() {
 	var (
 		expCommitment []byte

modules/core/04-channel/v2/types/expected_keepers.go

@@ -19,4 +19,6 @@ type ClientKeeper interface {
 	// GetClientTimestampAtHeight returns the timestamp for a given height on the client
 	// given its client ID and height
 	GetClientTimestampAtHeight(ctx context.Context, clientID string, height exported.Height) (uint64, error)
+	// GetClientState gets a particular client from the store
+	GetClientState(ctx context.Context, clientID string) (exported.ClientState, bool)
 }

modules/core/04-channel/v2/types/query.go

@@ -16,6 +16,22 @@ func NewQueryChannelResponse(channel Channel) *QueryChannelResponse {
 	}
 }
 
+// NewQueryChannelClientStateRequest creates and returns a new ChannelClientState query request.
+func NewQueryChannelClientStateRequest(channelID string) *QueryChannelClientStateRequest {
+	return &QueryChannelClientStateRequest{
+		ChannelId: channelID,
+	}
+}
+
+// NewQueryChannelClientStateResponse creates and returns a new ChannelClientState query response.
+func NewQueryChannelClientStateResponse(identifiedClientState clienttypes.IdentifiedClientState, proof []byte, height clienttypes.Height) *QueryChannelClientStateResponse {
+	return &QueryChannelClientStateResponse{
+		IdentifiedClientState: &identifiedClientState,
+		Proof:                 proof,
+		ProofHeight:           height,
+	}
+}
+
 // NewQueryNextSequenceSendRequest creates a new next sequence send query.
 func NewQueryNextSequenceSendRequest(channelID string) *QueryNextSequenceSendRequest {
 	return &QueryNextSequenceSendRequest{