From 2be32e25545ff3bc322b1e5b55de4aa5d4d394a3 Mon Sep 17 00:00:00 2001
From: bojie <bojie@dexon.org>
Date: Thu, 31 Jan 2019 18:23:46 +0800
Subject: transaction: use all transaction gas to reduce attack intention
 (#180)

The ci test in /tests will use origin evm logic.
---
 build/ci.go              | 18 ++++++++++++++++++
 core/state_transition.go | 26 +++++++++++++++++++++++++-
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/build/ci.go b/build/ci.go
index f49071295..810f7d69b 100644
--- a/build/ci.go
+++ b/build/ci.go
@@ -330,6 +330,15 @@ func doTest(cmdline []string) {
 	}
 	packages = build.ExpandPackagesNoVendor(packages)
 
+	packageForLegacyEvm := []string{}
+	for i := 0; i < len(packages); i++ {
+		if strings.HasSuffix(packages[i], "dexon/tests") {
+			packageForLegacyEvm = append(packageForLegacyEvm, packages[i])
+			packages = append(packages[:i], packages[i+1:]...)
+			i--
+		}
+	}
+
 	// Run the actual tests.
 	// Test a single package at a time. CI builders are slow
 	// and some tests run into timeouts under load.
@@ -341,6 +350,15 @@ func doTest(cmdline []string) {
 
 	gotest.Args = append(gotest.Args, packages...)
 	build.MustRun(gotest)
+
+	gotestForLegacyEvm := goTool("test", buildFlags(env)...)
+	gotestForLegacyEvm.Args = append(gotestForLegacyEvm.Args, "-p", "1", "-timeout", "5m")
+	if *coverage {
+		gotestForLegacyEvm.Args = append(gotestForLegacyEvm.Args, "-covermode=atomic", "-cover")
+	}
+	gotestForLegacyEvm.Args = append(gotestForLegacyEvm.Args, packageForLegacyEvm...)
+	gotestForLegacyEvm.Args = append(gotestForLegacyEvm.Args, "-legacy-evm=true")
+	build.MustRun(gotestForLegacyEvm)
 }
 
 // runs gometalinter on requested packages
diff --git a/core/state_transition.go b/core/state_transition.go
index 3b5ea6a2f..ce05e54a2 100644
--- a/core/state_transition.go
+++ b/core/state_transition.go
@@ -18,6 +18,7 @@ package core
 
 import (
 	"errors"
+	"flag"
 	"math"
 	"math/big"
 
@@ -27,6 +28,8 @@ import (
 	"github.com/dexon-foundation/dexon/params"
 )
 
+var legacyEvm = flag.Bool("legacy-evm", false, "make evm run origin logic")
+
 var (
 	errInsufficientBalanceForGas = errors.New("insufficient balance to pay for gas")
 )
@@ -221,12 +224,33 @@ func (st *StateTransition) TransitionDb() (ret []byte, usedGas uint64, failed bo
 			return nil, 0, false, vmerr
 		}
 	}
-	st.refundGas()
+
+	if *legacyEvm {
+		st.refundGas()
+	} else {
+		st.dexonRefundGas()
+	}
 	st.state.AddBalance(st.evm.Coinbase, new(big.Int).Mul(new(big.Int).SetUint64(st.gasUsed()), st.gasPrice))
 
 	return ret, st.gasUsed(), vmerr != nil, err
 }
 
+func (st *StateTransition) dexonRefundGas() {
+	// Apply refund counter, capped to half of the used gas.
+	refund := st.gasUsed() / 2
+	if refund > st.state.GetRefund() {
+		refund = st.state.GetRefund()
+	}
+
+	// Return ETH for remaining gas, exchanged at the original rate.
+	remaining := new(big.Int).Mul(new(big.Int).SetUint64(refund), st.gasPrice)
+	st.state.AddBalance(st.msg.From(), remaining)
+
+	// Also return remaining gas to the block gas counter so it is
+	// available for the next transaction.
+	st.gp.AddGas(refund)
+}
+
 func (st *StateTransition) refundGas() {
 	// Apply refund counter, capped to half of the used gas.
 	refund := st.gasUsed() / 2
-- 
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