Add FeeAccount to StdTx and add fee-delegation module

client/flags/flags.go

@@ -54,6 +54,7 @@ const (
 	FlagRPCWriteTimeout    = "write-timeout"
 	FlagOutputDocument     = "output-document" // inspired by wget -O
 	FlagSkipConfirmation   = "yes"
+	FlagFeeAccount         = "fee-account"
 )
 
 // LineBreak can be included in a command list to provide a blank line
@@ -99,6 +100,7 @@ func PostCommands(cmds ...*cobra.Command) []*cobra.Command {
 		c.Flags().Bool(FlagDryRun, false, "ignore the --gas flag and perform a simulation of a transaction, but don't broadcast it")
 		c.Flags().Bool(FlagGenerateOnly, false, "Build an unsigned transaction and write it to STDOUT (when enabled, the local Keybase is not accessible and the node operates offline)")
 		c.Flags().BoolP(FlagSkipConfirmation, "y", false, "Skip tx broadcasting prompt confirmation")
+		c.Flags().String(FlagFeeAccount, "", "Set a fee account to pay fess with if they have been delegated by this account")
 
 		// --gas can accept integers and "simulate"
 		c.Flags().Var(&GasFlagVar, "gas", fmt.Sprintf(

simapp/app.go

@@ -213,7 +213,7 @@ func NewSimApp(logger log.Logger, db dbm.DB, traceStore io.Writer, loadLatest bo
 	// initialize BaseApp
 	app.SetInitChainer(app.InitChainer)
 	app.SetBeginBlocker(app.BeginBlocker)
-	app.SetAnteHandler(auth.NewAnteHandler(app.accountKeeper, app.supplyKeeper, auth.DefaultSigVerificationGasConsumer))
+	app.SetAnteHandler(auth.NewAnteHandler(app.accountKeeper, app.supplyKeeper, nil, auth.DefaultSigVerificationGasConsumer))
 	app.SetEndBlocker(app.EndBlocker)
 
 	if loadLatest {

x/auth/ante.go

@@ -32,10 +32,16 @@ func init() {
 // and also to accept or reject different types of PubKey's. This is where apps can define their own PubKey
 type SignatureVerificationGasConsumer = func(meter sdk.GasMeter, sig []byte, pubkey crypto.PubKey, params Params) sdk.Result
 
+type FeeDelegationHandler interface {
+	// AllowDelegatedFees checks if the grantee can use the granter's account to spend the specified fees, updating
+	// any fee allowance in accordance with the provided fees
+	AllowDelegatedFees(ctx sdk.Context, grantee sdk.AccAddress, granter sdk.AccAddress, fee sdk.Coins) bool
+}
+
 // NewAnteHandler returns an AnteHandler that checks and increments sequence
 // numbers, checks signatures & account numbers, and deducts fees from the first
 // signer.
-func NewAnteHandler(ak AccountKeeper, supplyKeeper types.SupplyKeeper, sigGasConsumer SignatureVerificationGasConsumer) sdk.AnteHandler {
+func NewAnteHandler(ak AccountKeeper, supplyKeeper types.SupplyKeeper, feeDelegationHandler FeeDelegationHandler, sigGasConsumer SignatureVerificationGasConsumer) sdk.AnteHandler {
 	return func(
 		ctx sdk.Context, tx sdk.Tx, simulate bool,
 	) (newCtx sdk.Context, res sdk.Result, abort bool) {
@@ -110,34 +116,42 @@ func NewAnteHandler(ak AccountKeeper, supplyKeeper types.SupplyKeeper, sigGasCon
 		signerAccs := make([]Account, len(signerAddrs))
 		isGenesis := ctx.BlockHeight() == 0
 
-		// fetch first signer, who's going to pay the fees
-		signerAccs[0], res = GetSignerAcc(newCtx, ak, signerAddrs[0])
+		feeAddr := stdTx.FeeAccount
+		if len(feeAddr) != 0 {
+			// check if fees can be delegated
+			if feeDelegationHandler == nil {
+				return newCtx, sdk.ErrUnknownRequest("delegated fees aren't supported").Result(), true
+			}
+			if !feeDelegationHandler.AllowDelegatedFees(ctx, signerAddrs[0], feeAddr, stdTx.Fee.Amount) {
+				return newCtx, res, true
+			}
+		} else {
+			// use first signer, who's going to pay the fees
+			feeAddr = signerAddrs[0]
+		}
+
+		// pay fees with the fee account
+		feeAccount, res := GetSignerAcc(newCtx, ak, feeAddr)
 		if !res.IsOK() {
 			return newCtx, res, true
 		}
 
 		// deduct the fees
 		if !stdTx.Fee.Amount.IsZero() {
-			res = DeductFees(supplyKeeper, newCtx, signerAccs[0], stdTx.Fee.Amount)
+			res = DeductFees(supplyKeeper, newCtx, feeAccount, stdTx.Fee.Amount)
 			if !res.IsOK() {
 				return newCtx, res, true
 			}
-
-			// reload the account as fees have been deducted
-			signerAccs[0] = ak.GetAccount(newCtx, signerAccs[0].GetAddress())
 		}
 
 		// stdSigs contains the sequence number, account number, and signatures.
 		// When simulating, this would just be a 0-length slice.
 		stdSigs := stdTx.GetSignatures()
 
 		for i := 0; i < len(stdSigs); i++ {
-			// skip the fee payer, account is cached and fees were deducted already
-			if i != 0 {
-				signerAccs[i], res = GetSignerAcc(newCtx, ak, signerAddrs[i])
-				if !res.IsOK() {
-					return newCtx, res, true
-				}
+			signerAccs[i], res = GetSignerAcc(newCtx, ak, signerAddrs[i])
+			if !res.IsOK() {
+				return newCtx, res, true
 			}
 
 			// check signature, return account with incremented nonce
@@ -417,6 +431,6 @@ func GetSignBytes(chainID string, stdTx StdTx, acc Account, genesis bool) []byte
 	}
 
 	return StdSignBytes(
-		chainID, accNum, acc.GetSequence(), stdTx.Fee, stdTx.Msgs, stdTx.Memo,
+		chainID, accNum, acc.GetSequence(), stdTx.Fee, stdTx.Msgs, stdTx.Memo, stdTx.FeeAccount,
 	)
 }

x/auth/ante_test.go

@@ -49,7 +49,7 @@ func TestAnteHandlerSigErrors(t *testing.T) {
 	// setup
 	input := setupTestInput()
 	ctx := input.ctx
-	anteHandler := NewAnteHandler(input.ak, input.sk, DefaultSigVerificationGasConsumer)
+	anteHandler := NewAnteHandler(input.ak, input.sk, nil, DefaultSigVerificationGasConsumer)
 
 	// keys and addresses
 	priv1, _, addr1 := types.KeyTestPubAddr()
@@ -97,7 +97,7 @@ func TestAnteHandlerSigErrors(t *testing.T) {
 func TestAnteHandlerAccountNumbers(t *testing.T) {
 	// setup
 	input := setupTestInput()
-	anteHandler := NewAnteHandler(input.ak, input.sk, DefaultSigVerificationGasConsumer)
+	anteHandler := NewAnteHandler(input.ak, input.sk, nil, DefaultSigVerificationGasConsumer)
 	ctx := input.ctx.WithBlockHeight(1)
 
 	// keys and addresses
@@ -154,7 +154,7 @@ func TestAnteHandlerAccountNumbers(t *testing.T) {
 func TestAnteHandlerAccountNumbersAtBlockHeightZero(t *testing.T) {
 	// setup
 	input := setupTestInput()
-	anteHandler := NewAnteHandler(input.ak, input.sk, DefaultSigVerificationGasConsumer)
+	anteHandler := NewAnteHandler(input.ak, input.sk, nil, DefaultSigVerificationGasConsumer)
 	ctx := input.ctx.WithBlockHeight(0)
 
 	// keys and addresses
@@ -210,7 +210,7 @@ func TestAnteHandlerAccountNumbersAtBlockHeightZero(t *testing.T) {
 func TestAnteHandlerSequences(t *testing.T) {
 	// setup
 	input := setupTestInput()
-	anteHandler := NewAnteHandler(input.ak, input.sk, DefaultSigVerificationGasConsumer)
+	anteHandler := NewAnteHandler(input.ak, input.sk, nil, DefaultSigVerificationGasConsumer)
 	ctx := input.ctx.WithBlockHeight(1)
 
 	// keys and addresses
@@ -288,7 +288,7 @@ func TestAnteHandlerFees(t *testing.T) {
 	// setup
 	input := setupTestInput()
 	ctx := input.ctx
-	anteHandler := NewAnteHandler(input.ak, input.sk, DefaultSigVerificationGasConsumer)
+	anteHandler := NewAnteHandler(input.ak, input.sk, nil, DefaultSigVerificationGasConsumer)
 
 	// keys and addresses
 	priv1, _, addr1 := types.KeyTestPubAddr()
@@ -327,7 +327,7 @@ func TestAnteHandlerFees(t *testing.T) {
 func TestAnteHandlerMemoGas(t *testing.T) {
 	// setup
 	input := setupTestInput()
-	anteHandler := NewAnteHandler(input.ak, input.sk, DefaultSigVerificationGasConsumer)
+	anteHandler := NewAnteHandler(input.ak, input.sk, nil, DefaultSigVerificationGasConsumer)
 	ctx := input.ctx.WithBlockHeight(1)
 
 	// keys and addresses
@@ -367,7 +367,7 @@ func TestAnteHandlerMemoGas(t *testing.T) {
 func TestAnteHandlerMultiSigner(t *testing.T) {
 	// setup
 	input := setupTestInput()
-	anteHandler := NewAnteHandler(input.ak, input.sk, DefaultSigVerificationGasConsumer)
+	anteHandler := NewAnteHandler(input.ak, input.sk, nil, DefaultSigVerificationGasConsumer)
 	ctx := input.ctx.WithBlockHeight(1)
 
 	// keys and addresses
@@ -417,7 +417,7 @@ func TestAnteHandlerMultiSigner(t *testing.T) {
 func TestAnteHandlerBadSignBytes(t *testing.T) {
 	// setup
 	input := setupTestInput()
-	anteHandler := NewAnteHandler(input.ak, input.sk, DefaultSigVerificationGasConsumer)
+	anteHandler := NewAnteHandler(input.ak, input.sk, nil, DefaultSigVerificationGasConsumer)
 	ctx := input.ctx.WithBlockHeight(1)
 
 	// keys and addresses
@@ -472,7 +472,7 @@ func TestAnteHandlerBadSignBytes(t *testing.T) {
 	for _, cs := range cases {
 		tx := types.NewTestTxWithSignBytes(
 			msgs, privs, accnums, seqs, fee,
-			StdSignBytes(cs.chainID, cs.accnum, cs.seq, cs.fee, cs.msgs, ""),
+			StdSignBytes(cs.chainID, cs.accnum, cs.seq, cs.fee, cs.msgs, "", nil),
 			"",
 		)
 		checkInvalidTx(t, anteHandler, ctx, tx, false, cs.code)
@@ -494,7 +494,7 @@ func TestAnteHandlerBadSignBytes(t *testing.T) {
 func TestAnteHandlerSetPubKey(t *testing.T) {
 	// setup
 	input := setupTestInput()
-	anteHandler := NewAnteHandler(input.ak, input.sk, DefaultSigVerificationGasConsumer)
+	anteHandler := NewAnteHandler(input.ak, input.sk, nil, DefaultSigVerificationGasConsumer)
 	ctx := input.ctx.WithBlockHeight(1)
 
 	// keys and addresses
@@ -690,7 +690,7 @@ func TestCountSubkeys(t *testing.T) {
 func TestAnteHandlerSigLimitExceeded(t *testing.T) {
 	// setup
 	input := setupTestInput()
-	anteHandler := NewAnteHandler(input.ak, input.sk, DefaultSigVerificationGasConsumer)
+	anteHandler := NewAnteHandler(input.ak, input.sk, nil, DefaultSigVerificationGasConsumer)
 	ctx := input.ctx.WithBlockHeight(1)
 
 	// keys and addresses
@@ -780,7 +780,7 @@ func TestCustomSignatureVerificationGasConsumer(t *testing.T) {
 	// setup
 	input := setupTestInput()
 	// setup an ante handler that only accepts PubKeyEd25519
-	anteHandler := NewAnteHandler(input.ak, input.sk, func(meter sdk.GasMeter, sig []byte, pubkey crypto.PubKey, params Params) sdk.Result {
+	anteHandler := NewAnteHandler(input.ak, input.sk, nil, func(meter sdk.GasMeter, sig []byte, pubkey crypto.PubKey, params Params) sdk.Result {
 		switch pubkey := pubkey.(type) {
 		case ed25519.PubKeyEd25519:
 			meter.ConsumeGas(params.SigVerifyCostED25519, "ante verify: ed25519")

x/auth/client/cli/tx_multisign.go

@@ -102,7 +102,7 @@ func makeMultiSignCmd(cdc *codec.Codec) func(cmd *cobra.Command, args []string)
 			// Validate each signature
 			sigBytes := types.StdSignBytes(
 				txBldr.ChainID(), txBldr.AccountNumber(), txBldr.Sequence(),
-				stdTx.Fee, stdTx.GetMsgs(), stdTx.GetMemo(),
+				stdTx.Fee, stdTx.GetMsgs(), stdTx.GetMemo(), nil,
 			)
 			if ok := stdSig.PubKey.VerifyBytes(sigBytes, stdSig.Signature); !ok {
 				return fmt.Errorf("couldn't verify signature")
@@ -113,7 +113,7 @@ func makeMultiSignCmd(cdc *codec.Codec) func(cmd *cobra.Command, args []string)
 		}
 
 		newStdSig := types.StdSignature{Signature: cdc.MustMarshalBinaryBare(multisigSig), PubKey: multisigPub}
-		newTx := types.NewStdTx(stdTx.GetMsgs(), stdTx.Fee, []types.StdSignature{newStdSig}, stdTx.GetMemo())
+		newTx := types.NewStdTx(stdTx.GetMsgs(), stdTx.Fee, []types.StdSignature{newStdSig}, stdTx.GetMemo(), nil)
 
 		sigOnly := viper.GetBool(flagSigOnly)
 		var json []byte

x/auth/client/cli/tx_sign.go

@@ -230,7 +230,7 @@ func printAndValidateSigs(
 
 			sigBytes := types.StdSignBytes(
 				chainID, acc.GetAccountNumber(), acc.GetSequence(),
-				stdTx.Fee, stdTx.GetMsgs(), stdTx.GetMemo(),
+				stdTx.Fee, stdTx.GetMsgs(), stdTx.GetMemo(), stdTx.FeeAccount,
 			)
 
 			if ok := sig.VerifyBytes(sigBytes, sig.Signature); !ok {

x/auth/client/utils/rest.go

@@ -53,7 +53,7 @@ func WriteGenerateStdTxResponse(w http.ResponseWriter, cliCtx context.CLIContext
 		return
 	}
 
-	output, err := cliCtx.Codec.MarshalJSON(types.NewStdTx(stdMsg.Msgs, stdMsg.Fee, nil, stdMsg.Memo))
+	output, err := cliCtx.Codec.MarshalJSON(types.NewStdTx(stdMsg.Msgs, stdMsg.Fee, nil, stdMsg.Memo, stdMsg.FeeAccount))
 	if err != nil {
 		rest.WriteErrorResponse(w, http.StatusInternalServerError, err.Error())
 		return

x/auth/client/utils/tx.go

@@ -67,6 +67,17 @@ func CompleteAndBroadcastTxCLI(txBldr authtypes.TxBuilder, cliCtx context.CLICon
 		return nil
 	}
 
+	// support delegated fee payments
+	feeAccount := viper.GetString(flags.FlagFeeAccount)
+	if len(feeAccount) != 0 {
+		feeAcccountAddr, err := sdk.AccAddressFromBech32(feeAccount)
+		if err != nil {
+			return err
+		}
+        txBldr.WithFeeAccount(feeAcccountAddr)
+	}
+
+
 	if !cliCtx.SkipConfirm {
 		stdSignMsg, err := txBldr.BuildSignMsg(msgs)
 		if err != nil {
@@ -344,7 +355,7 @@ func buildUnsignedStdTxOffline(txBldr authtypes.TxBuilder, cliCtx context.CLICon
 		return stdTx, nil
 	}
 
-	return authtypes.NewStdTx(stdSignMsg.Msgs, stdSignMsg.Fee, nil, stdSignMsg.Memo), nil
+	return authtypes.NewStdTx(stdSignMsg.Msgs, stdSignMsg.Fee, nil, stdSignMsg.Memo, stdSignMsg.FeeAccount), nil
 }
 
 func isTxSigner(user sdk.AccAddress, signers []sdk.AccAddress) bool {

x/auth/client/utils/tx_test.go

@@ -98,7 +98,7 @@ func TestReadStdTxFromFile(t *testing.T) {
 
 	// Build a test transaction
 	fee := authtypes.NewStdFee(50000, sdk.Coins{sdk.NewInt64Coin("atom", 150)})
-	stdTx := authtypes.NewStdTx([]sdk.Msg{}, fee, []authtypes.StdSignature{}, "foomemo")
+	stdTx := authtypes.NewStdTx([]sdk.Msg{}, fee, []authtypes.StdSignature{}, "foomemo", nil)
 
 	// Write it to the file
 	encodedTx, _ := cdc.MarshalJSON(stdTx)
@@ -113,7 +113,7 @@ func TestReadStdTxFromFile(t *testing.T) {
 
 func compareEncoders(t *testing.T, expected sdk.TxEncoder, actual sdk.TxEncoder) {
 	msgs := []sdk.Msg{sdk.NewTestMsg(addr)}
-	tx := authtypes.NewStdTx(msgs, authtypes.StdFee{}, []authtypes.StdSignature{}, "")
+	tx := authtypes.NewStdTx(msgs, authtypes.StdFee{}, []authtypes.StdSignature{}, "", nil)
 
 	defaultEncoderBytes, err := expected(tx)
 	require.NoError(t, err)

x/auth/types/stdsignmsg.go

@@ -8,15 +8,16 @@ import (
 // a Msg with the other requirements for a StdSignDoc before
 // it is signed. For use in the CLI.
 type StdSignMsg struct {
-	ChainID       string    `json:"chain_id"`
-	AccountNumber uint64    `json:"account_number"`
-	Sequence      uint64    `json:"sequence"`
-	Fee           StdFee    `json:"fee"`
-	Msgs          []sdk.Msg `json:"msgs"`
-	Memo          string    `json:"memo"`
+	ChainID       string         `json:"chain_id"`
+	AccountNumber uint64         `json:"account_number"`
+	Sequence      uint64         `json:"sequence"`
+	Fee           StdFee         `json:"fee"`
+	Msgs          []sdk.Msg      `json:"msgs"`
+	Memo          string         `json:"memo"`
+	FeeAccount    sdk.AccAddress `json:"fee_account"`
 }
 
 // get message bytes
 func (msg StdSignMsg) Bytes() []byte {
-	return StdSignBytes(msg.ChainID, msg.AccountNumber, msg.Sequence, msg.Fee, msg.Msgs, msg.Memo)
+	return StdSignBytes(msg.ChainID, msg.AccountNumber, msg.Sequence, msg.Fee, msg.Msgs, msg.Memo, msg.FeeAccount)
 }

x/auth/types/stdtx.go

@@ -24,14 +24,18 @@ type StdTx struct {
 	Fee        StdFee         `json:"fee"`
 	Signatures []StdSignature `json:"signatures"`
 	Memo       string         `json:"memo"`
+	// FeeAccount is an optional account that fees can be spent from if such
+	// delegation is enabled
+	FeeAccount sdk.AccAddress `json:"fee_account"`
 }
 
-func NewStdTx(msgs []sdk.Msg, fee StdFee, sigs []StdSignature, memo string) StdTx {
+func NewStdTx(msgs []sdk.Msg, fee StdFee, sigs []StdSignature, memo string, feeAccount sdk.AccAddress) StdTx {
 	return StdTx{
 		Msgs:       msgs,
 		Fee:        fee,
 		Signatures: sigs,
 		Memo:       memo,
+		FeeAccount: feeAccount,
 	}
 }
 
@@ -163,10 +167,11 @@ type StdSignDoc struct {
 	Memo          string            `json:"memo"`
 	Msgs          []json.RawMessage `json:"msgs"`
 	Sequence      uint64            `json:"sequence"`
+	FeeAccount    []byte            `json:"fee_account"`
 }
 
 // StdSignBytes returns the bytes to sign for a transaction.
-func StdSignBytes(chainID string, accnum uint64, sequence uint64, fee StdFee, msgs []sdk.Msg, memo string) []byte {
+func StdSignBytes(chainID string, accnum uint64, sequence uint64, fee StdFee, msgs []sdk.Msg, memo string, feeAccount sdk.AccAddress) []byte {
 	var msgsBytes []json.RawMessage
 	for _, msg := range msgs {
 		msgsBytes = append(msgsBytes, json.RawMessage(msg.GetSignBytes()))
@@ -178,6 +183,7 @@ func StdSignBytes(chainID string, accnum uint64, sequence uint64, fee StdFee, ms
 		Memo:          memo,
 		Msgs:          msgsBytes,
 		Sequence:      sequence,
+		FeeAccount:    feeAccount,
 	})
 	if err != nil {
 		panic(err)
@@ -188,7 +194,7 @@ func StdSignBytes(chainID string, accnum uint64, sequence uint64, fee StdFee, ms
 // StdSignature represents a sig
 type StdSignature struct {
 	crypto.PubKey `json:"pub_key"` // optional
-	Signature     []byte           `json:"signature"`
+	Signature     []byte `json:"signature"`
 }
 
 // DefaultTxDecoder logic for standard transaction decoding