83 lines
2.8 KiB
Go
83 lines
2.8 KiB
Go
package ante
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import (
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"fmt"
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sdk "github.com/cosmos/cosmos-sdk/types"
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sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
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authante "github.com/cosmos/cosmos-sdk/x/auth/ante"
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authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
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"github.com/cosmos/cosmos-sdk/x/feegrant/keeper"
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"github.com/cosmos/cosmos-sdk/x/feegrant/types"
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)
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// DeductGrantedFeeDecorator deducts fees from fee_payer or fee_granter (if exists a valid fee allowance) of the tx
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// If the fee_payer or fee_granter does not have the funds to pay for the fees, return with InsufficientFunds error
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// Call next AnteHandler if fees successfully deducted
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// CONTRACT: Tx must implement GrantedFeeTx interface to use DeductGrantedFeeDecorator
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type DeductGrantedFeeDecorator struct {
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ak types.AccountKeeper
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k keeper.Keeper
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bk types.BankKeeper
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}
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func NewDeductGrantedFeeDecorator(ak types.AccountKeeper, bk types.BankKeeper, k keeper.Keeper) DeductGrantedFeeDecorator {
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return DeductGrantedFeeDecorator{
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ak: ak,
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k: k,
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bk: bk,
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}
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}
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// AnteHandle performs a decorated ante-handler responsible for deducting transaction
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// fees. Fees will be deducted from the account designated by the FeePayer on a
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// transaction by default. However, if the fee payer differs from the transaction
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// signer, the handler will check if a fee grant has been authorized. If the
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// transaction's signer does not exist, it will be created.
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func (d DeductGrantedFeeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
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feeTx, ok := tx.(sdk.FeeTx)
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if !ok {
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return ctx, sdkerrors.Wrap(sdkerrors.ErrTxDecode, "Tx must be a GrantedFeeTx")
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}
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// sanity check from DeductFeeDecorator
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if addr := d.ak.GetModuleAddress(authtypes.FeeCollectorName); addr == nil {
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panic(fmt.Sprintf("%s module account has not been set", authtypes.FeeCollectorName))
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}
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fee := feeTx.GetFee()
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feePayer := feeTx.FeePayer()
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feeGranter := feeTx.FeeGranter()
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deductFeesFrom := feePayer
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// ensure the grant is allowed, if we request a different fee payer
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if feeGranter != nil && !feeGranter.Equals(feePayer) {
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err := d.k.UseGrantedFees(ctx, feeGranter, feePayer, fee)
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if err != nil {
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return ctx, sdkerrors.Wrapf(err, "%s not allowed to pay fees from %s", feeGranter, feePayer)
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}
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deductFeesFrom = feeGranter
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}
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// now, either way, we know that we are authorized to deduct the fees from the deductFeesFrom account
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deductFeesFromAcc := d.ak.GetAccount(ctx, deductFeesFrom)
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if deductFeesFromAcc == nil {
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return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownAddress, "fee payer address: %s does not exist", deductFeesFrom)
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}
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// move on if there is no fee to deduct
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if fee.IsZero() {
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return next(ctx, tx, simulate)
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}
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// deduct fee if non-zero
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err = authante.DeductFees(d.bk, ctx, deductFeesFromAcc, fee)
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if err != nil {
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return ctx, err
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}
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return next(ctx, tx, simulate)
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}
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