allow ics20 to connect to middleware (#675)

* allow ics20 to connect to middleware

Creates ics4Wrapper which allows middleware applications to only implement SendPacket to connect ics20 as an application in its middleware stack

* add changelog and migration doc

* fix migration doc spelling

CHANGELOG.md

@@ -42,6 +42,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ### API Breaking
 
+* (transfer) [\#675](https://github.com/cosmos/ibc-go/pull/675) Transfer `NewKeeper` now takes in an ICS4Wrapper. The ICS4Wrapper may be the IBC Channel Keeper when ICS20 is not used in a middleware stack. The ICS4Wrapper is required for applications wishing to connect middleware to ICS20.
 * (core) [\#650](https://github.com/cosmos/ibc-go/pull/650) Modify `OnChanOpenTry` IBC application module callback to return the negotiated app version. The version passed into the `MsgChanOpenTry` has been deprecated and will be ignored by core IBC.
 * (core) [\#629](https://github.com/cosmos/ibc-go/pull/629) Removes the `GetProofSpecs` from the ClientState interface. This function was previously unused by core IBC.
 * (transfer) [\#517](https://github.com/cosmos/ibc-go/pull/517) Separates the ICS 26 callback functions from `AppModule` into a new type `IBCModule` for ICS 20 transfer.

docs/migrations/v2-to-v3.md

@@ -18,6 +18,13 @@ No genesis or in-place migrations are required when upgrading from v1 or v2 of i
 
 ## Chains
 
+### ICS20
+
+The `transferkeeper.NewKeeper(...)` now takes in an ICS4Wrapper. 
+The ICS4Wrapper should be the IBC Channel Keeper unless ICS 20 is being connected to a middleware application.
+
+### ICS27
+
 ICS27 Interchain Accounts has been added as a supported IBC application of ibc-go.
 Please see the [ICS27 documentation](../app_modules/interchain-accounts/overview.md) for more information.
 

modules/apps/27-interchain-accounts/controller/keeper/grpc_query.go

@@ -2,7 +2,9 @@ package keeper
 
 import (
 	"context"
+
 	sdk "github.com/cosmos/cosmos-sdk/types"
+
 	"github.com/cosmos/ibc-go/v3/modules/apps/27-interchain-accounts/controller/types"
 )
 

modules/apps/transfer/keeper/keeper.go

@@ -21,6 +21,7 @@ type Keeper struct {
 	cdc        codec.BinaryCodec
 	paramSpace paramtypes.Subspace
 
+	ics4Wrapper   types.ICS4Wrapper
 	channelKeeper types.ChannelKeeper
 	portKeeper    types.PortKeeper
 	authKeeper    types.AccountKeeper
@@ -31,7 +32,7 @@ type Keeper struct {
 // NewKeeper creates a new IBC transfer Keeper instance
 func NewKeeper(
 	cdc codec.BinaryCodec, key sdk.StoreKey, paramSpace paramtypes.Subspace,
-	channelKeeper types.ChannelKeeper, portKeeper types.PortKeeper,
+	ics4Wrapper types.ICS4Wrapper, channelKeeper types.ChannelKeeper, portKeeper types.PortKeeper,
 	authKeeper types.AccountKeeper, bankKeeper types.BankKeeper, scopedKeeper capabilitykeeper.ScopedKeeper,
 ) Keeper {
 
@@ -49,6 +50,7 @@ func NewKeeper(
 		cdc:           cdc,
 		storeKey:      key,
 		paramSpace:    paramSpace,
+		ics4Wrapper:   ics4Wrapper,
 		channelKeeper: channelKeeper,
 		portKeeper:    portKeeper,
 		authKeeper:    authKeeper,

modules/apps/transfer/keeper/relay.go

@@ -158,7 +158,7 @@ func (k Keeper) SendTransfer(
 		timeoutTimestamp,
 	)
 
-	if err := k.channelKeeper.SendPacket(ctx, channelCap, packet); err != nil {
+	if err := k.ics4Wrapper.SendPacket(ctx, channelCap, packet); err != nil {
 		return err
 	}
 

modules/apps/transfer/types/expected_keepers.go

@@ -24,11 +24,15 @@ type BankKeeper interface {
 	SendCoinsFromAccountToModule(ctx sdk.Context, senderAddr sdk.AccAddress, recipientModule string, amt sdk.Coins) error
 }
 
+// ICS4Wrapper defines the expected ICS4Wrapper for middleware
+type ICS4Wrapper interface {
+	SendPacket(ctx sdk.Context, channelCap *capabilitytypes.Capability, packet ibcexported.PacketI) error
+}
+
 // ChannelKeeper defines the expected IBC channel keeper
 type ChannelKeeper interface {
 	GetChannel(ctx sdk.Context, srcPort, srcChan string) (channel channeltypes.Channel, found bool)
 	GetNextSequenceSend(ctx sdk.Context, portID, channelID string) (uint64, bool)
-	SendPacket(ctx sdk.Context, channelCap *capabilitytypes.Capability, packet ibcexported.PacketI) error
 }
 
 // ClientKeeper defines the expected IBC client keeper

testing/simapp/app.go

@@ -341,7 +341,7 @@ func NewSimApp(
 	// Create Transfer Keepers
 	app.TransferKeeper = ibctransferkeeper.NewKeeper(
 		appCodec, keys[ibctransfertypes.StoreKey], app.GetSubspace(ibctransfertypes.ModuleName),
-		app.IBCKeeper.ChannelKeeper, &app.IBCKeeper.PortKeeper,
+		app.IBCKeeper.ChannelKeeper, app.IBCKeeper.ChannelKeeper, &app.IBCKeeper.PortKeeper,
 		app.AccountKeeper, app.BankKeeper, scopedTransferKeeper,
 	)
 	transferModule := transfer.NewAppModule(app.TransferKeeper)