feat: Add Support for Zero Fee Addresses (#53)

* feat: adds zero-fee addresses

* feat: uses command line flag for zerofeeaddress

* chore: cleanup

* chore: remove comment

cmd/utils/flags.go

@@ -497,6 +497,12 @@ var (
 		Category: flags.VMCategory,
 	}
 
+	ZeroFeeAddressesFlag = &cli.StringFlag{
+		Name:     "zeroofeeaddresses",
+		Usage:    "Comma separated list of addresses that are allowed to send transactions with zero fees",
+		Value:    "",
+		Category: flags.VMCategory,
+	}
 	// API options.
 	RPCGlobalGasCapFlag = &cli.Uint64Flag{
 		Name:     "rpc.gascap",
@@ -2119,8 +2125,14 @@ func MakeChain(ctx *cli.Context, stack *node.Node, readonly bool) (*core.BlockCh
 	if ctx.IsSet(CacheFlag.Name) || ctx.IsSet(CacheGCFlag.Name) {
 		cache.TrieDirtyLimit = ctx.Int(CacheFlag.Name) * ctx.Int(CacheGCFlag.Name) / 100
 	}
-	vmcfg := vm.Config{EnablePreimageRecording: ctx.Bool(VMEnableDebugFlag.Name)}
 
+	vmcfg := vm.Config{EnablePreimageRecording: ctx.Bool(VMEnableDebugFlag.Name)}
+	if ctx.IsSet(ZeroFeeAddressesFlag.Name) {
+		addressStrings := strings.Split(ctx.String(ZeroFeeAddressesFlag.Name), ",")
+		for _, addr := range addressStrings {
+			vmcfg.ZeroFeeAddresses = append(vmcfg.ZeroFeeAddresses, common.HexToAddress(strings.TrimSpace(addr)))
+		}
+	}
 	// Disable transaction indexing/unindexing by default.
 	chain, err := core.NewBlockChain(chainDb, cache, gspec, nil, engine, vmcfg, nil, nil)
 	if err != nil {

core/state_transition.go

@@ -20,6 +20,7 @@ import (
 	"fmt"
 	"math"
 	"math/big"
+	"slices"
 
 	"github.com/ethereum/go-ethereum/common"
 	cmath "github.com/ethereum/go-ethereum/common/math"
@@ -464,7 +465,12 @@ func (st *StateTransition) TransitionDb() (*ExecutionResult, error) {
 		// Send both base and prio fee to preconf.eth address
 		treasuryAccount := common.HexToAddress("0xfA0B0f5d298d28EFE4d35641724141ef19C05684")
 		bothFees := baseFee.Add(baseFee, priorityFee)
-		st.state.AddBalance(treasuryAccount, bothFees)
+
+		if slices.Contains(st.evm.Config.ZeroFeeAddresses, sender.Address()) {
+			st.state.AddBalance(sender.Address(), bothFees)
+		} else {
+			st.state.AddBalance(treasuryAccount, bothFees)
+		}
 	}
 
 	return &ExecutionResult{

core/vm/interpreter.go

@@ -35,10 +35,11 @@ const (
 
 // Config are the configuration options for the Interpreter
 type Config struct {
-	Tracer                  EVMLogger // Opcode logger
-	NoBaseFee               bool      // Forces the EIP-1559 baseFee to 0 (needed for 0 price calls)
-	EnablePreimageRecording bool      // Enables recording of SHA3/keccak preimages
-	ExtraEips               []int     // Additional EIPS that are to be enabled
+	Tracer                  EVMLogger        // Opcode logger
+	NoBaseFee               bool             // Forces the EIP-1559 baseFee to 0 (needed for 0 price calls)
+	EnablePreimageRecording bool             // Enables recording of SHA3/keccak preimages
+	ExtraEips               []int            // Additional EIPS that are to be enabled
+	ZeroFeeAddresses        []common.Address // Addresses that are allowed to send transactions with zero fees
 }
 
 // ScopeContext contains the things that are per-call, such as stack and memory,