From e91ab84dbe4ef87b2f182b88e5b252b5d414df28 Mon Sep 17 00:00:00 2001
From: Felix Lange <fjl@twurst.com>
Date: Tue, 17 Mar 2015 11:58:31 +0100
Subject: [PATCH] core/types: don't use Address zero value for invalid
 addresses

---
 core/types/transaction.go      | 59 ++++++++++++++++++++--------------
 core/types/transaction_test.go |  5 +--
 2 files changed, 37 insertions(+), 27 deletions(-)

diff --git a/core/types/transaction.go b/core/types/transaction.go
index 7f1447ef88..24035a3ae8 100644
--- a/core/types/transaction.go
+++ b/core/types/transaction.go
@@ -2,6 +2,7 @@ package types
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"math/big"
@@ -21,19 +22,19 @@ type Transaction struct {
 	AccountNonce uint64
 	Price        *big.Int
 	GasLimit     *big.Int
-	Recipient    common.Address
+	Recipient    *common.Address // nil means contract creation
 	Amount       *big.Int
 	Payload      []byte
 	V            byte
 	R, S         []byte
 }
 
-func NewContractCreationTx(amount, gasAmount, price *big.Int, data []byte) *Transaction {
-	return NewTransactionMessage(common.Address{}, amount, gasAmount, price, data)
+func NewContractCreationTx(amount, gasLimit, gasPrice *big.Int, data []byte) *Transaction {
+	return &Transaction{Recipient: nil, Amount: amount, GasLimit: gasLimit, Price: gasPrice, Payload: data}
 }
 
-func NewTransactionMessage(to common.Address, amount, gasAmount, price *big.Int, data []byte) *Transaction {
-	return &Transaction{Recipient: to, Amount: amount, Price: price, GasLimit: gasAmount, Payload: data}
+func NewTransactionMessage(to common.Address, amount, gasAmount, gasPrice *big.Int, data []byte) *Transaction {
+	return &Transaction{Recipient: &to, Amount: amount, GasLimit: gasAmount, Price: gasPrice, Payload: data}
 }
 
 func NewTransactionFromBytes(data []byte) *Transaction {
@@ -73,12 +74,21 @@ func (self *Transaction) SetNonce(AccountNonce uint64) {
 	self.AccountNonce = AccountNonce
 }
 
-func (self *Transaction) From() common.Address {
-	return self.sender()
+func (self *Transaction) From() (common.Address, error) {
+	pubkey := self.PublicKey()
+	if len(pubkey) == 0 || pubkey[0] != 4 {
+		return common.Address{}, errors.New("invalid public key")
+	}
+	var addr common.Address
+	copy(addr[:], crypto.Sha3(pubkey[1:]))
+	return addr, nil
 }
 
-func (self *Transaction) To() common.Address {
-	return self.Recipient
+// To returns the recipient of the transaction.
+// If transaction is a contract creation (with no recipient address)
+// To returns nil.
+func (tx *Transaction) To() *common.Address {
+	return tx.Recipient
 }
 
 func (tx *Transaction) Curve() (v byte, r []byte, s []byte) {
@@ -105,18 +115,6 @@ func (tx *Transaction) PublicKey() []byte {
 	return pubkey
 }
 
-func (tx *Transaction) sender() (a common.Address) {
-	pubkey := tx.PublicKey()
-
-	// Validate the returned key.
-	// Return nil if public key isn't in full format
-	if len(pubkey) == 0 || pubkey[0] != 4 {
-		return a
-	}
-	copy(a[:], crypto.Sha3(pubkey[1:]))
-	return a
-}
-
 func (tx *Transaction) SetSignatureValues(sig []byte) error {
 	tx.R = sig[:32]
 	tx.S = sig[32:64]
@@ -149,11 +147,22 @@ func (tx *Transaction) RlpEncode() []byte {
 }
 
 func (tx *Transaction) String() string {
+	var from, to string
+	if f, err := tx.From(); err != nil {
+		from = "[invalid sender]"
+	} else {
+		from = fmt.Sprintf("%x", f[:])
+	}
+	if t := tx.To(); t == nil {
+		to = "[contract creation]"
+	} else {
+		to = fmt.Sprintf("%x", t[:])
+	}
 	return fmt.Sprintf(`
 	TX(%x)
 	Contract: %v
-	From:     %x
-	To:       %x
+	From:     %s
+	To:       %s
 	Nonce:    %v
 	GasPrice: %v
 	GasLimit  %v
@@ -166,8 +175,8 @@ func (tx *Transaction) String() string {
 `,
 		tx.Hash(),
 		len(tx.Recipient) == 0,
-		tx.From(),
-		tx.To(),
+		from,
+		to,
 		tx.AccountNonce,
 		tx.Price,
 		tx.GasLimit,
diff --git a/core/types/transaction_test.go b/core/types/transaction_test.go
index 1af59436e0..0b0dfe3ffe 100644
--- a/core/types/transaction_test.go
+++ b/core/types/transaction_test.go
@@ -19,8 +19,9 @@ var (
 		nil,
 	)
 
-	rightvrsTx = &Transaction{
-		Recipient:    common.HexToAddress("b94f5374fce5edbc8e2a8697c15331677e6ebf0b"),
+	rightvrsRecipient = common.HexToAddress("b94f5374fce5edbc8e2a8697c15331677e6ebf0b")
+	rightvrsTx        = &Transaction{
+		Recipient:    &rightvrsRecipient,
 		AccountNonce: 3,
 		Price:        big.NewInt(1),
 		GasLimit:     big.NewInt(2000),