feat: add metadata for IBC tokens

docs/migrations/v7-to-v8.md

@@ -74,6 +74,10 @@ TODO: https://github.com/cosmos/ibc-go/pull/3505 (extra parameter added to trans
 	)
 ```
 
+### Transfer migration
+
+An automatic migration handler (TODO: add link after https://github.com/cosmos/ibc-go/pull/3104 is merged) is configured in the transfer module to set the [denomination metadata](https://github.com/cosmos/cosmos-sdk/blob/95178ce036741ae6aa7af131fa9fccf3e13fff7a/proto/cosmos/bank/v1beta1/bank.proto#L96-L125) for the IBC denominations of all vouchers minted by the transfer module.
+
 ## IBC Apps
 
 TODO: 

modules/apps/transfer/keeper/genesis.go

@@ -14,6 +14,7 @@ func (k Keeper) InitGenesis(ctx sdk.Context, state types.GenesisState) {
 
 	for _, trace := range state.DenomTraces {
 		k.SetDenomTrace(ctx, trace)
+		k.setDenomMetadata(ctx, trace)
 	}
 
 	// Only try to bind to port if it is not already bound, since we may already own

modules/apps/transfer/keeper/genesis_test.go

@@ -16,7 +16,7 @@ func (suite *KeeperTestSuite) TestGenesis() {
 	}
 
 	var (
-		traces                types.Traces
+		denomTraces           types.Traces
 		escrows               sdk.Coins
 		pathsAndEscrowAmounts = []struct {
 			path   string
@@ -35,7 +35,7 @@ func (suite *KeeperTestSuite) TestGenesis() {
 			BaseDenom: "uatom",
 			Path:      pathAndEscrowAmount.path,
 		}
-		traces = append(types.Traces{denomTrace}, traces...)
+		denomTraces = append(types.Traces{denomTrace}, denomTraces...)
 		suite.chainA.GetSimApp().TransferKeeper.SetDenomTrace(suite.chainA.GetContext(), denomTrace)
 
 		denom := denomTrace.IBCDenom()
@@ -48,10 +48,15 @@ func (suite *KeeperTestSuite) TestGenesis() {
 	genesis := suite.chainA.GetSimApp().TransferKeeper.ExportGenesis(suite.chainA.GetContext())
 
 	suite.Require().Equal(types.PortID, genesis.PortId)
-	suite.Require().Equal(traces.Sort(), genesis.DenomTraces)
+	suite.Require().Equal(denomTraces.Sort(), genesis.DenomTraces)
 	suite.Require().Equal(escrows.Sort(), genesis.TotalEscrowed)
 
 	suite.Require().NotPanics(func() {
 		suite.chainA.GetSimApp().TransferKeeper.InitGenesis(suite.chainA.GetContext(), *genesis)
 	})
+
+	for _, denomTrace := range denomTraces {
+		_, found := suite.chainA.GetSimApp().BankKeeper.GetDenomMetaData(suite.chainA.GetContext(), denomTrace.IBCDenom())
+		suite.Require().True(found)
+	}
 }

modules/apps/transfer/keeper/keeper.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	banktypes "github.com/cosmos/cosmos-sdk/x/bank/types"
 	paramtypes "github.com/cosmos/cosmos-sdk/x/params/types"
 
 	tmbytes "github.com/cometbft/cometbft/libs/bytes"
@@ -190,6 +191,28 @@ func (k Keeper) IterateDenomTraces(ctx sdk.Context, cb func(denomTrace types.Den
 	}
 }
 
+// setDenomMetadata sets an IBC token's denomination metadata
+func (k Keeper) setDenomMetadata(ctx sdk.Context, denomTrace types.DenomTrace) {
+	metadata := banktypes.Metadata{
+		Description: fmt.Sprintf("IBC token from %s", denomTrace.GetFullDenomPath()),
+		DenomUnits: []*banktypes.DenomUnit{
+			{
+				Denom:    denomTrace.BaseDenom,
+				Exponent: 0,
+			},
+		},
+		// Setting base as IBC hash denom since bank keepers's SetDenomMetadata uses
+		// Base as key path and the IBC hash is what gives this token uniqueness
+		// on the executing chain
+		Base:    denomTrace.IBCDenom(),
+		Display: denomTrace.GetFullDenomPath(),
+		Name:    fmt.Sprintf("%s IBC token", denomTrace.GetFullDenomPath()),
+		Symbol:  strings.ToUpper(denomTrace.BaseDenom),
+	}
+
+	k.bankKeeper.SetDenomMetaData(ctx, metadata)
+}
+
 // GetTotalEscrowForDenom gets the total amount of source chain tokens that
 // are in escrow, keyed by the denomination.
 //

modules/apps/transfer/keeper/migrations.go

@@ -55,6 +55,7 @@ func (m Migrator) MigrateTraces(ctx sdk.Context) error {
 			if !equalTraces(newTrace, dt) {
 				newTraces = append(newTraces, newTrace)
 			}
+
 			return false
 		})
 
@@ -65,6 +66,21 @@ func (m Migrator) MigrateTraces(ctx sdk.Context) error {
 	return nil
 }
 
+// MigrateDenomMetadata sets token metadata for all the IBC denom traces
+func (m Migrator) MigrateDenomMetadata(ctx sdk.Context) error {
+	m.keeper.IterateDenomTraces(ctx,
+		func(dt types.DenomTrace) (stop bool) {
+			// check if the metadata for the given denom trace does not already exist
+			if !m.keeper.bankKeeper.HasDenomMetaData(ctx, dt.IBCDenom()) {
+				m.keeper.setDenomMetadata(ctx, dt)
+			}
+			return false
+		})
+
+	m.keeper.Logger(ctx).Info("successfully added metadata to IBC voucher denominations")
+	return nil
+}
+
 // MigrateTotalEscrowForDenom migrates the total amount of source chain tokens in escrow.
 func (m Migrator) MigrateTotalEscrowForDenom(ctx sdk.Context) error {
 	var totalEscrowed sdk.Coins

modules/apps/transfer/keeper/migrations_test.go

@@ -7,6 +7,7 @@ import (
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	banktestutil "github.com/cosmos/cosmos-sdk/x/bank/testutil"
+	banktypes "github.com/cosmos/cosmos-sdk/x/bank/types"
 
 	transferkeeper "github.com/cosmos/ibc-go/v8/modules/apps/transfer/keeper"
 	transfertypes "github.com/cosmos/ibc-go/v8/modules/apps/transfer/types"
@@ -235,3 +236,185 @@ func (suite *KeeperTestSuite) TestMigrateTotalEscrowForDenom() {
 		})
 	}
 }
+
+func (suite *KeeperTestSuite) TestMigratorMigrateMetadata() {
+	var (
+		denomTraces      []transfertypes.DenomTrace
+		expectedMetadata []banktypes.Metadata
+	)
+
+	testCases := []struct {
+		msg      string
+		malleate func()
+	}{
+		{
+			"success with one denom trace with one hop",
+			func() {
+				denomTraces = []transfertypes.DenomTrace{
+					{
+						BaseDenom: "foo",
+						Path:      "transfer/channel-0",
+					},
+				}
+
+				expectedMetadata = []banktypes.Metadata{
+					{
+						Description: "IBC token from transfer/channel-0/foo",
+						DenomUnits: []*banktypes.DenomUnit{
+							{
+								Denom:    "foo",
+								Exponent: 0,
+							},
+						},
+						Base:    denomTraces[0].IBCDenom(), // ibc/EB7094899ACFB7A6F2A67DB084DEE2E9A83DEFAA5DEF92D9A9814FFD9FF673FA
+						Display: "transfer/channel-0/foo",
+						Name:    "transfer/channel-0/foo IBC token",
+						Symbol:  "FOO",
+					},
+				}
+			},
+		},
+		{
+			"success with one denom trace with two hops",
+			func() {
+				denomTraces = []transfertypes.DenomTrace{
+					{
+						BaseDenom: "ubar",
+						Path:      "transfer/channel-1/transfer/channel-2",
+					},
+				}
+
+				expectedMetadata = []banktypes.Metadata{
+					{
+						Description: "IBC token from transfer/channel-1/transfer/channel-2/ubar",
+						DenomUnits: []*banktypes.DenomUnit{
+							{
+								Denom:    "ubar",
+								Exponent: 0,
+							},
+						},
+						Base:    denomTraces[0].IBCDenom(), // ibc/8243B3EAA19BAB1DB3B0020B81C0C5A953E7B22C042CEE44E639A11A238BA57C
+						Display: "transfer/channel-1/transfer/channel-2/ubar",
+						Name:    "transfer/channel-1/transfer/channel-2/ubar IBC token",
+						Symbol:  "UBAR",
+					},
+				}
+			},
+		},
+		{
+			"success with two denom traces with one hop",
+			func() {
+				denomTraces = []transfertypes.DenomTrace{
+					{
+						BaseDenom: "foo",
+						Path:      "transfer/channel-0",
+					},
+					{
+						BaseDenom: "bar",
+						Path:      "transfer/channel-0",
+					},
+				}
+
+				expectedMetadata = []banktypes.Metadata{
+					{
+						Description: "IBC token from transfer/channel-0/foo",
+						DenomUnits: []*banktypes.DenomUnit{
+							{
+								Denom:    "foo",
+								Exponent: 0,
+							},
+						},
+						Base:    denomTraces[0].IBCDenom(), // ibc/EB7094899ACFB7A6F2A67DB084DEE2E9A83DEFAA5DEF92D9A9814FFD9FF673FA
+						Display: "transfer/channel-0/foo",
+						Name:    "transfer/channel-0/foo IBC token",
+						Symbol:  "FOO",
+					},
+					{
+						Description: "IBC token from transfer/channel-0/bar",
+						DenomUnits: []*banktypes.DenomUnit{
+							{
+								Denom:    "bar",
+								Exponent: 0,
+							},
+						},
+						Base:    denomTraces[1].IBCDenom(), // ibc/E1530E21F1848B6C29C9E89256D43E294976897611A61741CACBA55BE21736F5
+						Display: "transfer/channel-0/bar",
+						Name:    "transfer/channel-0/bar IBC token",
+						Symbol:  "BAR",
+					},
+				}
+			},
+		},
+		{
+			"success with two denom traces, metadata for one of them already exists",
+			func() {
+				denomTraces = []transfertypes.DenomTrace{
+					{
+						BaseDenom: "foo",
+						Path:      "transfer/channel-0",
+					},
+					{
+						BaseDenom: "bar",
+						Path:      "transfer/channel-0",
+					},
+				}
+
+				expectedMetadata = []banktypes.Metadata{
+					{
+						Description: "IBC token from transfer/channel-0/foo",
+						DenomUnits: []*banktypes.DenomUnit{
+							{
+								Denom:    "foo",
+								Exponent: 0,
+							},
+						},
+						Base:    denomTraces[0].IBCDenom(), // ibc/EB7094899ACFB7A6F2A67DB084DEE2E9A83DEFAA5DEF92D9A9814FFD9FF673FA
+						Display: "transfer/channel-0/foo",
+						Name:    "transfer/channel-0/foo IBC token",
+						Symbol:  "FOO",
+					},
+					{
+						Description: "IBC token from transfer/channel-0/bar",
+						DenomUnits: []*banktypes.DenomUnit{
+							{
+								Denom:    "bar",
+								Exponent: 0,
+							},
+						},
+						Base:    denomTraces[1].IBCDenom(), // ibc/E1530E21F1848B6C29C9E89256D43E294976897611A61741CACBA55BE21736F5
+						Display: "transfer/channel-0/bar",
+						Name:    "transfer/channel-0/bar IBC token",
+						Symbol:  "BAR",
+					},
+				}
+
+				// set metadata for one of the tokens, so that it exists already in state before doing the migration
+				suite.chainA.GetSimApp().BankKeeper.SetDenomMetaData(suite.chainA.GetContext(), expectedMetadata[1])
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		suite.Run(fmt.Sprintf("Case %s", tc.msg), func() {
+			suite.SetupTest() // reset
+			ctx := suite.chainA.GetContext()
+
+			tc.malleate()
+
+			for _, denomTrace := range denomTraces {
+				suite.chainA.GetSimApp().TransferKeeper.SetDenomTrace(ctx, denomTrace)
+			}
+
+			// run migration
+			migrator := transferkeeper.NewMigrator(suite.chainA.GetSimApp().TransferKeeper)
+			err := migrator.MigrateDenomMetadata(ctx)
+			suite.Require().NoError(err)
+
+			for _, expMetadata := range expectedMetadata {
+				denomMetadata, found := suite.chainA.GetSimApp().BankKeeper.GetDenomMetaData(ctx, expMetadata.Base)
+				suite.Require().True(found)
+				suite.Require().Equal(expMetadata, denomMetadata)
+			}
+		})
+	}
+}

modules/apps/transfer/keeper/relay.go

@@ -261,6 +261,10 @@ func (k Keeper) OnRecvPacket(ctx sdk.Context, packet channeltypes.Packet, data t
 	}
 
 	voucherDenom := denomTrace.IBCDenom()
+	if !k.bankKeeper.HasDenomMetaData(ctx, voucherDenom) {
+		k.setDenomMetadata(ctx, denomTrace)
+	}
+
 	ctx.EventManager().EmitEvent(
 		sdk.NewEvent(
 			types.EventTypeDenomTrace,