Add fee grant module (cosmos#8061)

* Add docs

* Add BasicFeeAllowance implementation

* Add expiration structs and complete basic fee

* Add delegation messages, add validation logic

* Add keeper and helper structs

* Add alias and handler to top level

* Add delegation module

* Add basic querier

* Add types tests

* Add types tests

* More internal test coverage

* Solid internal test coverage

* Expose Querier to top level module

* Add FeeAccount to auth/types, like StdTx, SignDoc

* Fix all tests in x/auth

* All tests pass

* Appease the Golang Linter

* Add fee-account command line flag

* Start on DelegatedDeductFeeDecorator

* Cleanup the Decorator

* Wire up delegation module in simapp

* add basic test for decorator (no delegation)

* Table tests for deduct fees

* Table tests over all conditions of delegated fee decorator

* Build full ante handler stack and test it

* Start genesis

* Implement Genesis

* Rename package delegation to subkeys

* Clarify antes test cases, handle empty account w/o fees

* Allow paying delegated fees with no account

* Pull mempool into delegated ante, for control on StdFee

* Use custom DelegatedTx, DelegatedFee for subkeys

* Revert all changes to x/auth.StdTx

* Appease scopelint

* Register DelegatedTx with codec

* Address PR comments

* Remove unnecessary DelegatedMempoolFeeDecorator

* Cleaned up errors in querier

* Clean up message sign bytes

* Minor PR comments

* Replace GetAllFees... with Iterator variants

* PrepareForExport adjusts grant expiration height

* Panic on de/serialization error in keeper

* Move custom ante handler chain to tests, update docs

* More cleanup

* More doc cleanup

* Renamed subkeys module to fee_grant

* Rename subkeys/delegation to fee grant in all strings

* Modify Msg and Keeper methods to use Grant not Delegate

* Add PeriodicFeeAllowance

* Update aliases

* Cover all accept cases for PeriodicFeeAllowance

* Et tu scopelint?

* Update docs as requested

* Remove error return from GetFeeGrant

* Code cleanup as requested by PR

* Updated all errors to use new sdk/errors package

* Use test suite for keeper tests

* Clean up alias.go file

* Define expected interfaces in exported, rather than importing from account

* Remove dependency on auth/ante

* Improve godoc, Logger

* Cleaned up ExpiresAt

* Improve error reporting with UseGrantedFee

* Enforce period limit subset of basic limit

* Add events

* Rename fee_grant to feegrant

* Ensure KeeperTestSuite actually runs

* Move types/tx to types

* Update alias file, include ante

* I do need nolint in alias.go

* Properly emit events in the handler. Use cosmos-sdk in amino types

* Update godoc

* Linting...

* Update errors

* Update pkg doc and fix ante-handler order

* Merge PR cosmos#5782: Migrate x/feegrant to proto

* fix errors

* proto changes

* proto changes

* fix errors

* fix errors

* genesis state changed to proto

* fix keeper tests

* fix test

* fixed tests

* fix tests

* updated expected keepers

* updated ante tests

* lint

* deleted alias.go

* tx updated to proto tx

* remove explicit signmode

* tests

* Added `cli/query.go`

* Added tx.go in cli

* updated `module.go`

* resolve errors in tx.go

* Add fee payer gentx func

* updated tx

* fixed error

* WIP: cli tests

* fix query error

* fix tests

* Unused types and funcs

* fix tests

* rename helper func to create tx

* remove unused

* update tx cfg

* fix cli tests

* added simulations

* Add `decoder.go`

* fix build fail

* added init genesis code

* update tx.go

* fixed LGTM alert

* modified cli

* remove gogoproto extensions

* change acc address type to string

* lint

* fix simulations

* Add gen simulations

* remove legacy querier

* remove legacy code

* add grpc queries tests

* fix simulations

* update module.go

* lint

* register feegrant NewSimulationManager

* fix sims

* fix sims

* add genesis test

* add periodic grant

* updated cmd

* changed times

* updated flags

* removed days as period clock

* added condition for period and exp

* add periodic fee cli tests

* udpated tests

* fix lint

* fix tests

* fix sims

* renaming to `fee_grant`

* review changes

* fix test

* add condition for duplicate grants

* fix tests

* add `genTxWithFeeGranter` in tests

* fix simulation

* one of changes & test fixes

* fix test

* fix lint

* changed package name `feegrant` to `fee_grant`

* review comments

* review changes

* review change

* review changes

* added fee-account in flags

* address review changes

* read fee granter from cli

* updated create account with mnemonic

* Address review comments

* move `simapp/ante` file to `feegrant/ante`

* update keeper logic to create account

* update docs

* fix tests

* update `serviceMsgClientConn` from `msgservice`

* review changes

* add test case for using more fees than allowed

* eliminate panic checks from keeper

* fix lint

* change store keys string to bytes

* fix tests

* review changes

* review changes

* udpate docs

* make spend limit optional

* fix tests

* fix tests

* review changes

* add norace tag

* proto-docs

* add docs

Co-authored-by: Ethan Frey <ethanfrey@users.noreply.github.com>
Co-authored-by: Alexander Bezobchuk <alexanderbez@users.noreply.github.com>
Co-authored-by: Aleksandr Bezobchuk <aleks.bezobchuk@gmail.com>
Co-authored-by: SaReN <sahithnarahari@gmail.com>
Co-authored-by: aleem1413 <aleem@vitwit.com>
Co-authored-by: MD Aleem <72057206+aleem1314@users.noreply.github.com>
Co-authored-by: Anil Kumar Kammari <anil@vitwit.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

client/cmd.go

@@ -221,6 +221,19 @@ func readTxCommandFlags(clientCtx Context, flagSet *pflag.FlagSet) (Context, err
 		clientCtx = clientCtx.WithSignModeStr(signModeStr)
 	}
 
+	if clientCtx.FeeGranter == nil || flagSet.Changed(flags.FlagFeeAccount) {
+		granter, _ := flagSet.GetString(flags.FlagFeeAccount)
+
+		if granter != "" {
+			granterAcc, err := sdk.AccAddressFromBech32(granter)
+			if err != nil {
+				return clientCtx, err
+			}
+
+			clientCtx = clientCtx.WithFeeGranterAddress(granterAcc)
+		}
+	}
+
 	if clientCtx.From == "" || flagSet.Changed(flags.FlagFrom) {
 		from, _ := flagSet.GetString(flags.FlagFrom)
 		fromAddr, fromName, keyType, err := GetFromFields(clientCtx.Keyring, from, clientCtx.GenerateOnly)

client/context.go

@@ -44,6 +44,7 @@ type Context struct {
 	TxConfig          TxConfig
 	AccountRetriever  AccountRetriever
 	NodeURI           string
+	FeeGranter        sdk.AccAddress
 
 	// TODO: Deprecated (remove).
 	LegacyAmino *codec.LegacyAmino
@@ -166,6 +167,13 @@ func (ctx Context) WithFromAddress(addr sdk.AccAddress) Context {
 	return ctx
 }
 
+// WithFeeGranterAddress returns a copy of the context with an updated fee granter account
+// address.
+func (ctx Context) WithFeeGranterAddress(addr sdk.AccAddress) Context {
+	ctx.FeeGranter = addr
+	return ctx
+}
+
 // WithBroadcastMode returns a copy of the context with an updated broadcast
 // mode.
 func (ctx Context) WithBroadcastMode(mode string) Context {

client/flags/flags.go

@@ -70,6 +70,7 @@ const (
 	FlagCountTotal       = "count-total"
 	FlagTimeoutHeight    = "timeout-height"
 	FlagKeyAlgorithm     = "algo"
+	FlagFeeAccount       = "fee-account"
 
 	// Tendermint logging flags
 	FlagLogLevel  = "log_level"
@@ -112,6 +113,7 @@ func AddTxFlagsToCmd(cmd *cobra.Command) {
 	cmd.Flags().String(FlagKeyringBackend, DefaultKeyringBackend, "Select keyring's backend (os|file|kwallet|pass|test)")
 	cmd.Flags().String(FlagSignMode, "", "Choose sign mode (direct|amino-json), this is an advanced feature")
 	cmd.Flags().Uint64(FlagTimeoutHeight, 0, "Set a block timeout height to prevent the tx from being committed past a certain height")
+	cmd.Flags().String(FlagFeeAccount, "", "Fee account pays fees for the transaction instead of deducting from the signer")
 
 	// --gas can accept integers and "auto"
 	cmd.Flags().String(FlagGas, "", fmt.Sprintf("gas limit to set per-transaction; set to %q to calculate sufficient gas automatically (default %d)", GasFlagAuto, DefaultGasLimit))

client/query.go

@@ -57,6 +57,11 @@ func (ctx Context) GetFromAddress() sdk.AccAddress {
 	return ctx.FromAddress
 }
 
+// GetFeeGranterAddress returns the fee granter address from the context
+func (ctx Context) GetFeeGranterAddress() sdk.AccAddress {
+	return ctx.FeeGranter
+}
+
 // GetFromName returns the key name for the current context.
 func (ctx Context) GetFromName() string {
 	return ctx.FromName

client/tx/tx.go

@@ -117,6 +117,7 @@ func BroadcastTx(clientCtx client.Context, txf Factory, msgs ...sdk.Msg) error {
 		}
 	}
 
+	tx.SetFeeGranter(clientCtx.GetFeeGranterAddress())
 	err = Sign(txf, clientCtx.GetFromName(), tx, true)
 	if err != nil {
 		return err

client/tx_config.go

@@ -42,5 +42,6 @@ type (
 		SetFeeAmount(amount sdk.Coins)
 		SetGasLimit(limit uint64)
 		SetTimeoutHeight(height uint64)
+		SetFeeGranter(feeGranter sdk.AccAddress)
 	}
 )

proto/cosmos/feegrant/v1beta1/feegrant.proto

@@ -0,0 +1,81 @@
+syntax = "proto3";
+package cosmos.feegrant.v1beta1;
+
+import "gogoproto/gogo.proto";
+import "google/protobuf/any.proto";
+import "cosmos_proto/cosmos.proto";
+import "cosmos/base/v1beta1/coin.proto";
+import "google/protobuf/timestamp.proto";
+import "google/protobuf/duration.proto";
+
+option go_package = "github.com/cosmos/cosmos-sdk/x/feegrant/types";
+
+// BasicFeeAllowance implements FeeAllowance with a one-time grant of tokens
+// that optionally expires. The delegatee can use up to SpendLimit to cover fees.
+message BasicFeeAllowance {
+  option (cosmos_proto.implements_interface) = "FeeAllowanceI";
+
+  // spend_limit specifies the maximum amount of tokens that can be spent
+  // by this allowance and will be updated as tokens are spent. If it is
+  // empty, there is no spend limit and any amount of coins can be spent.
+  repeated cosmos.base.v1beta1.Coin spend_limit = 1
+      [(gogoproto.nullable) = false, (gogoproto.castrepeated) = "github.com/cosmos/cosmos-sdk/types.Coins"];
+
+  // expiration specifies an optional time when this allowance expires
+  ExpiresAt expiration = 2 [(gogoproto.nullable) = false];
+}
+
+// PeriodicFeeAllowance extends FeeAllowance to allow for both a maximum cap,
+// as well as a limit per time period.
+message PeriodicFeeAllowance {
+  option (cosmos_proto.implements_interface) = "FeeAllowanceI";
+
+  // basic specifies a struct of `BasicFeeAllowance`
+  BasicFeeAllowance basic = 1 [(gogoproto.nullable) = false];
+
+  // period specifies the time duration in which period_spend_limit coins can
+  // be spent before that allowance is reset
+  Duration period = 2 [(gogoproto.nullable) = false];
+
+  // period_spend_limit specifies the maximum number of coins that can be spent
+  // in the period
+  repeated cosmos.base.v1beta1.Coin period_spend_limit = 3
+      [(gogoproto.nullable) = false, (gogoproto.castrepeated) = "github.com/cosmos/cosmos-sdk/types.Coins"];
+
+  // period_can_spend is the number of coins left to be spent before the period_reset time
+  repeated cosmos.base.v1beta1.Coin period_can_spend = 4
+      [(gogoproto.nullable) = false, (gogoproto.castrepeated) = "github.com/cosmos/cosmos-sdk/types.Coins"];
+
+  // period_reset is the time at which this period resets and a new one begins,
+  // it is calculated from the start time of the first transaction after the
+  // last period ended
+  ExpiresAt period_reset = 5 [(gogoproto.nullable) = false];
+}
+
+// Duration is a span of a clock time or number of blocks.
+// This is designed to be added to an ExpiresAt struct.
+message Duration {
+  // sum is the oneof that represents either duration or block
+  oneof sum {
+    google.protobuf.Duration duration = 1 [(gogoproto.stdduration) = true];
+    uint64                   blocks   = 2;
+  }
+}
+
+// ExpiresAt is a point in time where something expires.
+// It may be *either* block time or block height
+message ExpiresAt {
+  // sum is the oneof that represents either time or height
+  oneof sum {
+    google.protobuf.Timestamp time   = 1 [(gogoproto.stdtime) = true];
+    int64                     height = 2;
+  }
+}
+
+// FeeAllowanceGrant is stored in the KVStore to record a grant with full context
+message FeeAllowanceGrant {
+
+  string              granter   = 1;
+  string              grantee   = 2;
+  google.protobuf.Any allowance = 3 [(cosmos_proto.accepts_interface) = "FeeAllowanceI"];
+}

proto/cosmos/feegrant/v1beta1/genesis.proto

@@ -0,0 +1,12 @@
+syntax = "proto3";
+package cosmos.feegrant.v1beta1;
+
+import "gogoproto/gogo.proto";
+import "cosmos/feegrant/v1beta1/feegrant.proto";
+
+option go_package = "github.com/cosmos/cosmos-sdk/x/feegrant/types";
+
+// GenesisState contains a set of fee allowances, persisted from the store
+message GenesisState {
+  repeated FeeAllowanceGrant fee_allowances = 1 [(gogoproto.nullable) = false];
+}

proto/cosmos/feegrant/v1beta1/query.proto

@@ -0,0 +1,52 @@
+syntax = "proto3";
+package cosmos.feegrant.v1beta1;
+
+import "gogoproto/gogo.proto";
+import "cosmos/feegrant/v1beta1/feegrant.proto";
+import "cosmos/base/query/v1beta1/pagination.proto";
+import "google/api/annotations.proto";
+
+option go_package = "github.com/cosmos/cosmos-sdk/x/feegrant/types";
+
+// Query defines the gRPC querier service.
+service Query {
+
+  // FeeAllowance returns fee granted to the grantee by the granter.
+  rpc FeeAllowance(QueryFeeAllowanceRequest) returns (QueryFeeAllowanceResponse) {
+    option (google.api.http).get = "/cosmos/feegrant/v1beta1/fee_allowance/{granter}/{grantee}";
+  }
+
+  // FeeAllowances returns all the grants for address.
+  rpc FeeAllowances(QueryFeeAllowancesRequest) returns (QueryFeeAllowancesResponse) {
+    option (google.api.http).get = "/cosmos/feegrant/v1beta1/fee_allowances/{grantee}";
+  }
+}
+
+// QueryFeeAllowanceRequest is the request type for the Query/FeeAllowance RPC method.
+message QueryFeeAllowanceRequest {
+  string granter = 1;
+  string grantee = 2;
+}
+
+// QueryFeeAllowanceResponse is the response type for the Query/FeeAllowance RPC method.
+message QueryFeeAllowanceResponse {
+  // fee_allowance is a fee_allowance granted for grantee by granter.
+  cosmos.feegrant.v1beta1.FeeAllowanceGrant fee_allowance = 1;
+}
+
+// QueryFeeAllowancesRequest is the request type for the Query/FeeAllowances RPC method.
+message QueryFeeAllowancesRequest {
+  string grantee = 1;
+
+  // pagination defines an pagination for the request.
+  cosmos.base.query.v1beta1.PageRequest pagination = 2;
+}
+
+// QueryFeeAllowancesResponse is the response type for the Query/FeeAllowances RPC method.
+message QueryFeeAllowancesResponse {
+  // fee_allowances are fee_allowance's granted for grantee by granter.
+  repeated cosmos.feegrant.v1beta1.FeeAllowanceGrant fee_allowances = 1;
+
+  // pagination defines an pagination for the response.
+  cosmos.base.query.v1beta1.PageResponse pagination = 2;
+}

proto/cosmos/feegrant/v1beta1/tx.proto

@@ -0,0 +1,40 @@
+syntax = "proto3";
+package cosmos.feegrant.v1beta1;
+
+import "gogoproto/gogo.proto";
+import "google/protobuf/any.proto";
+import "cosmos_proto/cosmos.proto";
+
+option go_package = "github.com/cosmos/cosmos-sdk/x/feegrant/types";
+
+// Msg defines the feegrant msg service.
+service Msg {
+
+  // GrantFeeAllowance grants fee allowance to the grantee on the granter's
+  // account with the provided expiration time.
+  rpc GrantFeeAllowance(MsgGrantFeeAllowance) returns (MsgGrantFeeAllowanceResponse);
+
+  // RevokeFeeAllowance revokes any fee allowance of granter's account that
+  // has been granted to the grantee.
+  rpc RevokeFeeAllowance(MsgRevokeFeeAllowance) returns (MsgRevokeFeeAllowanceResponse);
+}
+
+// MsgGrantFeeAllowance adds permission for Grantee to spend up to Allowance
+// of fees from the account of Granter.
+message MsgGrantFeeAllowance {
+  string              granter   = 1;
+  string              grantee   = 2;
+  google.protobuf.Any allowance = 3 [(cosmos_proto.accepts_interface) = "FeeAllowanceI"];
+}
+
+// MsgGrantFeeAllowanceResponse defines the Msg/GrantFeeAllowanceResponse response type.
+message MsgGrantFeeAllowanceResponse {}
+
+// MsgRevokeFeeAllowance removes any existing FeeAllowance from Granter to Grantee.
+message MsgRevokeFeeAllowance {
+  string granter = 1;
+  string grantee = 2;
+}
+
+// MsgRevokeFeeAllowanceResponse defines the Msg/RevokeFeeAllowanceResponse response type.
+message MsgRevokeFeeAllowanceResponse {}

simapp/app.go

@@ -55,6 +55,10 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/evidence"
 	evidencekeeper "github.com/cosmos/cosmos-sdk/x/evidence/keeper"
 	evidencetypes "github.com/cosmos/cosmos-sdk/x/evidence/types"
+	feegrant "github.com/cosmos/cosmos-sdk/x/feegrant"
+	feegrantante "github.com/cosmos/cosmos-sdk/x/feegrant/ante"
+	feegrantkeeper "github.com/cosmos/cosmos-sdk/x/feegrant/keeper"
+	feegranttypes "github.com/cosmos/cosmos-sdk/x/feegrant/types"
 	"github.com/cosmos/cosmos-sdk/x/genutil"
 	genutiltypes "github.com/cosmos/cosmos-sdk/x/genutil/types"
 	"github.com/cosmos/cosmos-sdk/x/gov"
@@ -120,6 +124,7 @@ var (
 		crisis.AppModuleBasic{},
 		slashing.AppModuleBasic{},
 		ibc.AppModuleBasic{},
+		feegrant.AppModuleBasic{},
 		upgrade.AppModuleBasic{},
 		evidence.AppModuleBasic{},
 		transfer.AppModuleBasic{},
@@ -181,6 +186,7 @@ type SimApp struct {
 	IBCKeeper        *ibckeeper.Keeper // IBC Keeper must be a pointer in the app, so we can SetRouter on it correctly
 	EvidenceKeeper   evidencekeeper.Keeper
 	TransferKeeper   ibctransferkeeper.Keeper
+	FeeGrantKeeper   feegrantkeeper.Keeper
 
 	// make scoped keepers public for test purposes
 	ScopedIBCKeeper      capabilitykeeper.ScopedKeeper
@@ -222,7 +228,7 @@ func NewSimApp(
 	keys := sdk.NewKVStoreKeys(
 		authtypes.StoreKey, banktypes.StoreKey, stakingtypes.StoreKey,
 		minttypes.StoreKey, distrtypes.StoreKey, slashingtypes.StoreKey,
-		govtypes.StoreKey, paramstypes.StoreKey, ibchost.StoreKey, upgradetypes.StoreKey,
+		govtypes.StoreKey, paramstypes.StoreKey, ibchost.StoreKey, upgradetypes.StoreKey, feegranttypes.StoreKey,
 		evidencetypes.StoreKey, ibctransfertypes.StoreKey, capabilitytypes.StoreKey,
 		authztypes.StoreKey,
 	)
@@ -277,6 +283,8 @@ func NewSimApp(
 	app.CrisisKeeper = crisiskeeper.NewKeeper(
 		app.GetSubspace(crisistypes.ModuleName), invCheckPeriod, app.BankKeeper, authtypes.FeeCollectorName,
 	)
+
+	app.FeeGrantKeeper = feegrantkeeper.NewKeeper(appCodec, keys[feegranttypes.StoreKey], app.AccountKeeper)
 	app.UpgradeKeeper = upgradekeeper.NewKeeper(skipUpgradeHeights, keys[upgradetypes.StoreKey], appCodec, homePath)
 
 	// register the staking hooks
@@ -347,6 +355,7 @@ func NewSimApp(
 		bank.NewAppModule(appCodec, app.BankKeeper, app.AccountKeeper),
 		capability.NewAppModule(appCodec, *app.CapabilityKeeper),
 		crisis.NewAppModule(&app.CrisisKeeper, skipGenesisInvariants),
+		feegrant.NewAppModule(appCodec, app.AccountKeeper, app.BankKeeper, app.FeeGrantKeeper, app.interfaceRegistry),
 		gov.NewAppModule(appCodec, app.GovKeeper, app.AccountKeeper, app.BankKeeper),
 		mint.NewAppModule(appCodec, app.MintKeeper, app.AccountKeeper),
 		slashing.NewAppModule(appCodec, app.SlashingKeeper, app.AccountKeeper, app.BankKeeper, app.StakingKeeper),
@@ -379,6 +388,7 @@ func NewSimApp(
 		capabilitytypes.ModuleName, authtypes.ModuleName, banktypes.ModuleName, distrtypes.ModuleName, stakingtypes.ModuleName,
 		slashingtypes.ModuleName, govtypes.ModuleName, minttypes.ModuleName, crisistypes.ModuleName,
 		ibchost.ModuleName, genutiltypes.ModuleName, evidencetypes.ModuleName, authztypes.ModuleName, ibctransfertypes.ModuleName,
+		feegranttypes.ModuleName,
 	)
 
 	app.mm.RegisterInvariants(&app.CrisisKeeper)
@@ -396,6 +406,7 @@ func NewSimApp(
 		auth.NewAppModule(appCodec, app.AccountKeeper, authsims.RandomGenesisAccounts),
 		bank.NewAppModule(appCodec, app.BankKeeper, app.AccountKeeper),
 		capability.NewAppModule(appCodec, *app.CapabilityKeeper),
+		feegrant.NewAppModule(appCodec, app.AccountKeeper, app.BankKeeper, app.FeeGrantKeeper, app.interfaceRegistry),
 		gov.NewAppModule(appCodec, app.GovKeeper, app.AccountKeeper, app.BankKeeper),
 		mint.NewAppModule(appCodec, app.MintKeeper, app.AccountKeeper),
 		staking.NewAppModule(appCodec, app.StakingKeeper, app.AccountKeeper, app.BankKeeper),
@@ -419,8 +430,8 @@ func NewSimApp(
 	app.SetInitChainer(app.InitChainer)
 	app.SetBeginBlocker(app.BeginBlocker)
 	app.SetAnteHandler(
-		ante.NewAnteHandler(
-			app.AccountKeeper, app.BankKeeper, ante.DefaultSigVerificationGasConsumer,
+		feegrantante.NewAnteHandler(
+			app.AccountKeeper, app.BankKeeper, app.FeeGrantKeeper, ante.DefaultSigVerificationGasConsumer,
 			encodingConfig.TxConfig.SignModeHandler(),
 		),
 	)

simapp/params/weights.go

@@ -20,4 +20,8 @@ const (
 	DefaultWeightCommunitySpendProposal int = 5
 	DefaultWeightTextProposal           int = 5
 	DefaultWeightParamChangeProposal    int = 5
+
+	// feegrant
+	DefaultWeightGrantFeeAllowance  int = 100
+	DefaultWeightRevokeFeeAllowance int = 100
 )

x/auth/legacy/legacytx/stdtx_builder.go

@@ -84,6 +84,9 @@ func (s *StdTxBuilder) SetTimeoutHeight(height uint64) {
 	s.TimeoutHeight = height
 }
 
+// SetFeeGranter does nothing for stdtx
+func (s *StdTxBuilder) SetFeeGranter(_ sdk.AccAddress) {}
+
 // StdTxConfig is a context.TxConfig for StdTx
 type StdTxConfig struct {
 	Cdc *codec.LegacyAmino