Add fee grant module

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 +1,64 @@
+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";
+
+  repeated cosmos.base.v1beta1.Coin spend_limit = 1
+      [(gogoproto.nullable) = false, (gogoproto.castrepeated) = "github.com/cosmos/cosmos-sdk/types.Coins"];
+  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";
+
+  BasicFeeAllowance basic                              = 1 [(gogoproto.nullable) = false];
+  Duration          period                             = 2 [(gogoproto.nullable) = false];
+  repeated cosmos.base.v1beta1.Coin period_spend_limit = 3
+      [(gogoproto.nullable) = false, (gogoproto.castrepeated) = "github.com/cosmos/cosmos-sdk/types.Coins"];
+  repeated cosmos.base.v1beta1.Coin period_can_spend = 4
+      [(gogoproto.nullable) = false, (gogoproto.castrepeated) = "github.com/cosmos/cosmos-sdk/types.Coins"];
+
+  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

x/feegrant/ante/ante.go

@@ -0,0 +1,35 @@
+package ante
+
+import (
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	authante "github.com/cosmos/cosmos-sdk/x/auth/ante"
+	authkeeper "github.com/cosmos/cosmos-sdk/x/auth/keeper"
+	"github.com/cosmos/cosmos-sdk/x/auth/signing"
+	feegrantkeeper "github.com/cosmos/cosmos-sdk/x/feegrant/keeper"
+	feegranttypes "github.com/cosmos/cosmos-sdk/x/feegrant/types"
+)
+
+// NewAnteHandler returns an AnteHandler that checks and increments sequence
+// numbers, checks signatures & account numbers, and deducts fees from the
+// fee_payer or from fee_granter (if valid grant exist).
+func NewAnteHandler(
+	ak authkeeper.AccountKeeper, bankKeeper feegranttypes.BankKeeper, feeGrantKeeper feegrantkeeper.Keeper,
+	sigGasConsumer authante.SignatureVerificationGasConsumer, signModeHandler signing.SignModeHandler,
+) sdk.AnteHandler {
+
+	return sdk.ChainAnteDecorators(
+		authante.NewSetUpContextDecorator(), // outermost AnteDecorator. SetUpContext must be called first
+		authante.NewRejectExtensionOptionsDecorator(),
+		authante.NewMempoolFeeDecorator(),
+		authante.NewValidateBasicDecorator(),
+		authante.TxTimeoutHeightDecorator{},
+		authante.NewValidateMemoDecorator(ak),
+		authante.NewConsumeGasForTxSizeDecorator(ak),
+		NewDeductGrantedFeeDecorator(ak, bankKeeper, feeGrantKeeper),
+		authante.NewSetPubKeyDecorator(ak), // SetPubKeyDecorator must be called before all signature verification decorators
+		authante.NewValidateSigCountDecorator(ak),
+		authante.NewSigGasConsumeDecorator(ak, sigGasConsumer),
+		authante.NewSigVerificationDecorator(ak, signModeHandler),
+		authante.NewIncrementSequenceDecorator(ak), // innermost AnteDecorator
+	)
+}