core/types: add Transaction.From for deposit txs (#571)

Author: sebastianst

core/types/deposit_test.go

@@ -22,6 +22,7 @@ import (
 
 	"github.com/ethereum/go-ethereum/accounts/abi"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/stretchr/testify/require"
 )
 
 var (
@@ -93,3 +94,18 @@ func FuzzUnpackIntoDeposit(f *testing.F) {
 		}
 	})
 }
+
+func TestDepositTxFrom(t *testing.T) {
+	from := common.HexToAddress("0x1234567890123456789012345678901234567890")
+	dtx := &DepositTx{From: from}
+	tx := NewTx(dtx)
+	require.Equal(t, from, tx.From())
+
+	dtxwn := &depositTxWithNonce{DepositTx: *dtx}
+	tx = NewTx(dtxwn)
+	require.Equal(t, from, tx.From())
+
+	dftx := new(DynamicFeeTx)
+	tx = NewTx(dftx)
+	require.Panics(t, func() { tx.From() })
+}

core/types/deposit_tx.go

@@ -77,6 +77,7 @@ func (tx *DepositTx) gasTipCap() *big.Int    { return new(big.Int) }
 func (tx *DepositTx) gasPrice() *big.Int     { return new(big.Int) }
 func (tx *DepositTx) value() *big.Int        { return tx.Value }
 func (tx *DepositTx) nonce() uint64          { return 0 }
+func (tx *DepositTx) from() common.Address   { return tx.From }
 func (tx *DepositTx) to() *common.Address    { return tx.To }
 func (tx *DepositTx) isSystemTx() bool       { return tx.IsSystemTransaction }
 
@@ -105,3 +106,14 @@ func (tx *DepositTx) encode(b *bytes.Buffer) error {
 func (tx *DepositTx) decode(input []byte) error {
 	return rlp.DecodeBytes(input, tx)
 }
+
+// From is an OP-Stack addition to the Transaction type to easily get a deposit
+// transaction sender address.
+// It can be difficult to create a correct signer just to extract the From field
+// from a deposit transaction if the chain ID is not known.
+func (tx *Transaction) From() common.Address {
+	if tx.Type() != DepositTxType {
+		panic("From() called on non-deposit transaction")
+	}
+	return tx.inner.(interface{ from() common.Address }).from()
+}