feat(erc20): ERC-20 transactions

CHANGELOG.md

@@ -40,6 +40,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 ### Features
 
 - (p256) [#1922](https://github.com/evmos/evmos/pull/1922) [EIP-7212](https://eips.ethereum.org/EIPS/eip-7212) `secp256r1` curve precompile
+- (erc20) [#1993](https://github.com/evmos/evmos/pull/1993) Add ERC-20 Precompile transactions.
 
 ### Improvements
 

precompiles/erc20/tx.go

@@ -3,8 +3,14 @@
 package erc20
 
 import (
+	"math/big"
+
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	bankkeeper "github.com/cosmos/cosmos-sdk/x/bank/keeper"
 	banktypes "github.com/cosmos/cosmos-sdk/x/bank/types"
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/vm"
 )
 
 const (
@@ -18,3 +24,79 @@ const (
 
 // SendMsgURL defines the authorization type for MsgSend
 var SendMsgURL = sdk.MsgTypeURL(&banktypes.MsgSend{})
+
+// Transfer executes a direct transfer from the caller address to the
+// destination address.
+func (p Precompile) Transfer(
+	ctx sdk.Context,
+	contract *vm.Contract,
+	stateDB vm.StateDB,
+	method *abi.Method,
+	args []interface{},
+) ([]byte, error) {
+	from := contract.CallerAddress
+	to, amount, err := ParseTransferArgs(args)
+	if err != nil {
+		return nil, err
+	}
+
+	return p.transfer(ctx, contract, stateDB, method, from, to, amount)
+}
+
+// TransferFrom executes a transfer on behalf of the specified from address in
+// the call data to the destination address.
+func (p Precompile) TransferFrom(
+	ctx sdk.Context,
+	contract *vm.Contract,
+	stateDB vm.StateDB,
+	method *abi.Method,
+	args []interface{},
+) ([]byte, error) {
+	from, to, amount, err := ParseTransferFromArgs(args)
+	if err != nil {
+		return nil, err
+	}
+
+	return p.transfer(ctx, contract, stateDB, method, from, to, amount)
+}
+
+// transfer is a common function that handles transfers for the ERC-20 Transfer
+// and TransferFrom methods. It executes a bank Send message if the spender is
+// the sender of the transfer, otherwise it executes an authorization.
+func (p Precompile) transfer(
+	ctx sdk.Context,
+	contract *vm.Contract,
+	stateDB vm.StateDB,
+	method *abi.Method,
+	from, to common.Address,
+	amount *big.Int,
+) (data []byte, err error) {
+	coins := sdk.Coins{{Denom: p.tokenPair.Denom, Amount: sdk.NewIntFromBigInt(amount)}}
+
+	msg := banktypes.NewMsgSend(from.Bytes(), to.Bytes(), coins)
+
+	if err := msg.ValidateBasic(); err != nil {
+		return nil, err
+	}
+
+	sender := sdk.AccAddress(from.Bytes())
+	spender := sdk.AccAddress(contract.CallerAddress.Bytes()) // aka. grantee
+
+	if sender.Equals(spender) {
+		msgSrv := bankkeeper.NewMsgServerImpl(p.bankKeeper)
+		_, err = msgSrv.Send(sdk.WrapSDKContext(ctx), msg)
+	} else {
+		_, err = p.AuthzKeeper.DispatchActions(ctx, spender, []sdk.Msg{msg})
+	}
+
+	if err != nil {
+		// TODO: check if we need to return an error here
+		return method.Outputs.Pack(false)
+	}
+
+	if err := p.EmitTransferEvent(ctx, stateDB, from, to, amount); err != nil {
+		return nil, err
+	}
+
+	return method.Outputs.Pack(true)
+}