feat: add localhost client + testing

modules/core/02-client/genesis.go

@@ -8,6 +8,7 @@ import (
 	"github.com/cosmos/ibc-go/v6/modules/core/02-client/keeper"
 	"github.com/cosmos/ibc-go/v6/modules/core/02-client/types"
 	"github.com/cosmos/ibc-go/v6/modules/core/exported"
+	localhosttypes "github.com/cosmos/ibc-go/v6/modules/light-clients/09-localhost/types"
 )
 
 // InitGenesis initializes the ibc client submodule's state from a provided genesis
@@ -46,6 +47,12 @@ func InitGenesis(ctx sdk.Context, k keeper.Keeper, gs types.GenesisState) {
 	}
 
 	k.SetNextClientSequence(ctx, gs.NextClientSequence)
+
+	if gs.CreateLocalhost {
+		revision := uint64(0)
+		clientState := localhosttypes.NewClientState("", types.NewHeight(revision, 1)) // height start at block 1
+		k.SetClientState(ctx, exported.Localhost, clientState)
+	}
 }
 
 // ExportGenesis returns the ibc client submodule's exported genesis.

modules/core/02-client/keeper/keeper.go

@@ -270,6 +270,11 @@ func (k Keeper) GetSelfConsensusState(ctx sdk.Context, height exported.Height) (
 // Client must be in same revision as the executing chain
 func (k Keeper) ValidateSelfClient(ctx sdk.Context, clientState exported.ClientState) error {
 	tmClient, ok := clientState.(*ibctm.ClientState)
+
+	if clientState.ClientType() == exported.Localhost {
+		return nil
+	}
+
 	if !ok {
 		return sdkerrors.Wrapf(types.ErrInvalidClient, "client must be a Tendermint client, expected: %T, got: %T",
 			&ibctm.ClientState{}, tmClient)

modules/core/02-client/types/genesis.go

@@ -89,7 +89,7 @@ func DefaultGenesisState() GenesisState {
 		Clients:            []IdentifiedClientState{},
 		ClientsConsensus:   ClientsConsensusStates{},
 		Params:             DefaultParams(),
-		CreateLocalhost:    false,
+		CreateLocalhost:    true,
 		NextClientSequence: 0,
 	}
 }

modules/core/02-client/types/keys.go

@@ -9,6 +9,7 @@ import (
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 
 	host "github.com/cosmos/ibc-go/v6/modules/core/24-host"
+	"github.com/cosmos/ibc-go/v6/modules/core/exported"
 )
 
 const (
@@ -45,6 +46,11 @@ func IsValidClientID(clientID string) bool {
 
 // ParseClientIdentifier parses the client type and sequence from the client identifier.
 func ParseClientIdentifier(clientID string) (string, uint64, error) {
+	// Localhost client ID == client type
+	if clientID == exported.Localhost {
+		return clientID, 0, nil
+	}
+
 	if !IsClientIDFormat(clientID) {
 		return "", 0, sdkerrors.Wrapf(host.ErrInvalidID, "invalid client identifier %s is not in format: `{client-type}-{N}`", clientID)
 	}

modules/core/02-client/types/params.go

@@ -11,7 +11,7 @@ import (
 
 var (
 	// DefaultAllowedClients are "06-solomachine" and "07-tendermint"
-	DefaultAllowedClients = []string{exported.Solomachine, exported.Tendermint}
+	DefaultAllowedClients = []string{exported.Solomachine, exported.Tendermint, exported.Localhost}
 
 	// KeyAllowedClients is store's key for AllowedClients Params
 	KeyAllowedClients = []byte("AllowedClients")

modules/core/03-connection/keeper/handshake.go

@@ -74,12 +74,8 @@ func (k Keeper) ConnOpenTry(
 	// generate a new connection
 	connectionID := k.GenerateConnectionIdentifier(ctx)
 
-	selfHeight := clienttypes.GetSelfHeight(ctx)
-	if consensusHeight.GTE(selfHeight) {
-		return "", sdkerrors.Wrapf(
-			sdkerrors.ErrInvalidHeight,
-			"consensus height is greater than or equal to the current block height (%s >= %s)", consensusHeight, selfHeight,
-		)
+	if err := k.validateHeight(ctx, clientState.ClientType(), consensusHeight); err != nil {
+		return "", err
 	}
 
 	// validate client parameters of a chainB client stored on chainA
@@ -163,13 +159,8 @@ func (k Keeper) ConnOpenAck(
 	proofHeight exported.Height, // height that relayer constructed proofTry
 	consensusHeight exported.Height, // latest height of chainA that chainB has stored on its chainA client
 ) error {
-	// Check that chainB client hasn't stored invalid height
-	selfHeight := clienttypes.GetSelfHeight(ctx)
-	if consensusHeight.GTE(selfHeight) {
-		return sdkerrors.Wrapf(
-			sdkerrors.ErrInvalidHeight,
-			"consensus height is greater than or equal to the current block height (%s >= %s)", consensusHeight, selfHeight,
-		)
+	if err := k.validateHeight(ctx, clientState.ClientType(), consensusHeight); err != nil {
+		return err
 	}
 
 	// Retrieve connection
@@ -295,3 +286,22 @@ func (k Keeper) ConnOpenConfirm(
 
 	return nil
 }
+
+func (k Keeper) validateHeight(
+	ctx sdk.Context,
+	clientType string,
+	consensusHeight exported.Height, // latest height of chain B which chain A has stored in its chain B client
+) error {
+	if clientType == exported.Localhost {
+		return nil
+	}
+
+	selfHeight := clienttypes.GetSelfHeight(ctx)
+	if consensusHeight.GTE(selfHeight) {
+		return sdkerrors.Wrapf(
+			sdkerrors.ErrInvalidHeight,
+			"consensus height is greater than or equal to the current block height (%s >= %s)", consensusHeight, selfHeight,
+		)
+	}
+	return nil
+}

modules/core/03-connection/keeper/keeper.go

@@ -86,6 +86,11 @@ func (k Keeper) SetConnection(ctx sdk.Context, connectionID string, connection t
 // GetTimestampAtHeight returns the timestamp in nanoseconds of the consensus state at the
 // given height.
 func (k Keeper) GetTimestampAtHeight(ctx sdk.Context, connection types.ConnectionEnd, height exported.Height) (uint64, error) {
+	// Localhost client does not have a consensus state, use current block time.
+	if connection.ClientId == exported.Localhost {
+		return uint64(ctx.BlockTime().UnixNano()), nil
+	}
+
 	clientState, found := k.clientKeeper.GetClientState(ctx, connection.GetClientID())
 	if !found {
 		return 0, sdkerrors.Wrapf(