From c44830ebf316bf22104d01aa114d2b6d765d7a76 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A9ter=20Szil=C3=A1gyi?= <peterke@gmail.com>
Date: Fri, 16 Dec 2016 13:19:02 +0200
Subject: [PATCH] core, light: allow zero cost txs from inexistent accounts too

---
 core/tx_pool.go      | 24 ++++++++----------------
 core/tx_pool_test.go |  4 ----
 light/txpool.go      | 13 +------------
 3 files changed, 9 insertions(+), 32 deletions(-)

diff --git a/core/tx_pool.go b/core/tx_pool.go
index 65e076df9c..c5421fa021 100644
--- a/core/tx_pool.go
+++ b/core/tx_pool.go
@@ -37,15 +37,14 @@ import (
 
 var (
 	// Transaction Pool Errors
-	ErrInvalidSender      = errors.New("Invalid sender")
-	ErrNonce              = errors.New("Nonce too low")
-	ErrCheap              = errors.New("Gas price too low for acceptance")
-	ErrBalance            = errors.New("Insufficient balance")
-	ErrNonExistentAccount = errors.New("Account does not exist or account balance too low")
-	ErrInsufficientFunds  = errors.New("Insufficient funds for gas * price + value")
-	ErrIntrinsicGas       = errors.New("Intrinsic gas too low")
-	ErrGasLimit           = errors.New("Exceeds block gas limit")
-	ErrNegativeValue      = errors.New("Negative value")
+	ErrInvalidSender     = errors.New("Invalid sender")
+	ErrNonce             = errors.New("Nonce too low")
+	ErrCheap             = errors.New("Gas price too low for acceptance")
+	ErrBalance           = errors.New("Insufficient balance")
+	ErrInsufficientFunds = errors.New("Insufficient funds for gas * price + value")
+	ErrIntrinsicGas      = errors.New("Intrinsic gas too low")
+	ErrGasLimit          = errors.New("Exceeds block gas limit")
+	ErrNegativeValue     = errors.New("Negative value")
 )
 
 var (
@@ -287,13 +286,6 @@ func (pool *TxPool) validateTx(tx *types.Transaction) error {
 	if err != nil {
 		return ErrInvalidSender
 	}
-
-	// Make sure the account exist. Non existent accounts
-	// haven't got funds and well therefor never pass.
-	if !currentState.Exist(from) {
-		return ErrNonExistentAccount
-	}
-
 	// Last but not least check for nonce errors
 	if currentState.GetNonce(from) > tx.Nonce() {
 		return ErrNonce
diff --git a/core/tx_pool_test.go b/core/tx_pool_test.go
index 3e516735b3..f5fcac19f5 100644
--- a/core/tx_pool_test.go
+++ b/core/tx_pool_test.go
@@ -129,10 +129,6 @@ func TestInvalidTransactions(t *testing.T) {
 	pool, key := setupTxPool()
 
 	tx := transaction(0, big.NewInt(100), key)
-	if err := pool.Add(tx); err != ErrNonExistentAccount {
-		t.Error("expected", ErrNonExistentAccount)
-	}
-
 	from, _ := deriveSender(tx)
 	currentState, _ := pool.currentState()
 	currentState.AddBalance(from, big.NewInt(1))
diff --git a/light/txpool.go b/light/txpool.go
index 4a06d317d8..d0781593b0 100644
--- a/light/txpool.go
+++ b/light/txpool.go
@@ -346,19 +346,8 @@ func (pool *TxPool) validateTx(ctx context.Context, tx *types.Transaction) error
 	if from, err = types.Sender(pool.signer, tx); err != nil {
 		return core.ErrInvalidSender
 	}
-
-	// Make sure the account exist. Non existent accounts
-	// haven't got funds and well therefor never pass.
-	currentState := pool.currentState()
-	if h, err := currentState.HasAccount(ctx, from); err == nil {
-		if !h {
-			return core.ErrNonExistentAccount
-		}
-	} else {
-		return err
-	}
-
 	// Last but not least check for nonce errors
+	currentState := pool.currentState()
 	if n, err := currentState.GetNonce(ctx, from); err == nil {
 		if n > tx.Nonce() {
 			return core.ErrNonce