core, core/vm, crypto: fixes for homestead

* Removed some strange code that didn't apply state reverting properly
* Refactored code setting from vm & state transition to the executioner
* Updated tests

20 files changed, 210 insertions, 191 deletions

diff --git a/core/block_validator.go b/core/block_validator.go
index 901744c61..73c33d8dd 100644
--- a/core/block_validator.go
+++ b/core/block_validator.go
@@ -117,8 +117,7 @@ func (v *BlockValidator) ValidateState(block, parent *types.Block, statedb *stat
 	// For valid blocks this should always validate to true.
 	rbloom := types.CreateBloom(receipts)
 	if rbloom != header.Bloom {
-		//fmt.Printf("FUNKY: ValidateState: block number: %v\n", block.Number())
-		return fmt.Errorf("unable to replicate block's bloom=%x", rbloom)
+		return fmt.Errorf("unable to replicate block's bloom=%x vs calculated bloom=%x", header.Bloom, rbloom)
 	}
 	// Tre receipt Trie's root (R = (Tr [[H1, R1], ... [Hn, R1]]))
 	receiptSha := types.DeriveSha(receipts)
@@ -270,10 +269,6 @@ func calcDifficultyHomestead(time, parentTime uint64, parentNumber, parentDiff *
 	bigTime := new(big.Int).SetUint64(time)
 	bigParentTime := new(big.Int).SetUint64(parentTime)
 
-	// for the exponential factor
-	periodCount := new(big.Int).Add(parentNumber, common.Big1)
-	periodCount.Div(periodCount, ExpDiffPeriod)
-
 	// holds intermediate values to make the algo easier to read & audit
 	x := new(big.Int)
 	y := new(big.Int)
@@ -298,6 +293,10 @@ func calcDifficultyHomestead(time, parentTime uint64, parentNumber, parentDiff *
 		x = params.MinimumDifficulty
 	}
 
+	// for the exponential factor
+	periodCount := new(big.Int).Add(parentNumber, common.Big1)
+	periodCount.Div(periodCount, ExpDiffPeriod)
+
 	// the exponential factor, commonly refered to as "the bomb"
 	// diff = diff + 2^(periodCount - 2)
 	if periodCount.Cmp(common.Big1) > 0 {
diff --git a/core/database_util.go b/core/database_util.go
index 18ca1f44c..fd2b4c312 100644
--- a/core/database_util.go
+++ b/core/database_util.go
@@ -95,20 +95,6 @@ func GetHeadFastBlockHash(db ethdb.Database) common.Hash {
 	return common.BytesToHash(data)
 }
 
-// GetHeadBlockNum retrieves the block number of the current canonical head block.
-func GetHeadBlockNum(db ethdb.Database) *big.Int {
-	data, _ := db.Get(headBlockKey)
-	if len(data) == 0 {
-		return nil
-	}
-	header := new(types.Header)
-	if err := rlp.Decode(bytes.NewReader(data), header); err != nil {
-		glog.V(logger.Error).Infof("invalid block header RLP for head block: %v", err)
-		return nil
-	}
-	return header.Number
-}
-
 // GetHeaderRLP retrieves a block header in its raw RLP database encoding, or nil
 // if the header's not found.
 func GetHeaderRLP(db ethdb.Database, hash common.Hash) rlp.RawValue {
diff --git a/core/database_util_test.go b/core/database_util_test.go
index 059f1ae9f..6b3793635 100644
--- a/core/database_util_test.go
+++ b/core/database_util_test.go
@@ -62,7 +62,7 @@ func (d *diffTest) UnmarshalJSON(b []byte) (err error) {
 	return nil
 }
 
-func TestDifficulty(t *testing.T) {
+func TestDifficultyFrontier(t *testing.T) {
 	file, err := os.Open("../tests/files/BasicTests/difficulty.json")
 	if err != nil {
 		t.Fatal(err)
@@ -77,7 +77,7 @@ func TestDifficulty(t *testing.T) {
 
 	for name, test := range tests {
 		number := new(big.Int).Sub(test.CurrentBlocknumber, big.NewInt(1))
-		diff := CalcDifficulty(test.CurrentTimestamp, test.ParentTimestamp, number, test.ParentDifficulty)
+		diff := calcDifficultyFrontier(test.CurrentTimestamp, test.ParentTimestamp, number, test.ParentDifficulty)
 		if diff.Cmp(test.CurrentDifficulty) != 0 {
 			t.Error(name, "failed. Expected", test.CurrentDifficulty, "and calculated", diff)
 		}
diff --git a/core/execution.go b/core/execution.go
index 0c7e8cc9f..24c0c93ae 100644
--- a/core/execution.go
+++ b/core/execution.go
@@ -44,7 +44,6 @@ func DelegateCall(env vm.Environment, caller vm.ContractRef, addr common.Address
 	originAddr := env.Origin()
 	callerValue := caller.Value()
 	ret, _, err = execDelegateCall(env, caller, &originAddr, &callerAddr, &addr, input, env.Db().GetCode(addr), gas, gasPrice, callerValue)
-	caller.SetAddress(callerAddr)
 	return ret, err
 }
 
@@ -78,15 +77,15 @@ func exec(env vm.Environment, caller vm.ContractRef, address, codeAddr *common.A
 
 	var createAccount bool
 	if address == nil {
-		// Generate a new address
+		// Create a new account on the state
 		nonce := env.Db().GetNonce(caller.Address())
 		env.Db().SetNonce(caller.Address(), nonce+1)
 		addr = crypto.CreateAddress(caller.Address(), nonce)
 		address = &addr
 		createAccount = true
 	}
-	snapshotPreTransfer := env.MakeSnapshot()
 
+	snapshotPreTransfer := env.MakeSnapshot()
 	var (
 		from = env.Db().GetAccount(caller.Address())
 		to   vm.Account
@@ -101,24 +100,38 @@ func exec(env vm.Environment, caller vm.ContractRef, address, codeAddr *common.A
 		}
 	}
 	env.Transfer(from, to, value)
-	snapshotPostTransfer := env.MakeSnapshot()
 
+	// initialise a new contract and set the code that is to be used by the
+	// EVM. The contract is a scoped environment for this execution context
+	// only.
 	contract := vm.NewContract(caller, to, value, gas, gasPrice)
 	contract.SetCallCode(codeAddr, code)
+	defer contract.Finalise()
 
 	ret, err = evm.Run(contract, input)
-
-	if err != nil {
-		if err == vm.CodeStoreOutOfGasError {
-			// TODO: this is rather hacky, restore all state changes
-			// except sender's account nonce increment
-			toNonce := env.Db().GetNonce(to.Address())
-			env.SetSnapshot(snapshotPostTransfer)
-			env.Db().SetNonce(to.Address(), toNonce)
+	// if the contract creation ran successfully and no errors were returned
+	// calculate the gas required to store the code. If the code could not
+	// be stored due to not enough gas set an error and let it be handled
+	// by the error checking condition below.
+	if err == nil && createAccount {
+		dataGas := big.NewInt(int64(len(ret)))
+		dataGas.Mul(dataGas, params.CreateDataGas)
+		if contract.UseGas(dataGas) {
+			env.Db().SetCode(*address, ret)
 		} else {
-			env.SetSnapshot(snapshotPreTransfer) //env.Db().Set(snapshot)
+			err = vm.CodeStoreOutOfGasError
 		}
 	}
+
+	// When an error was returned by the EVM or when setting the creation code
+	// above we revert to the snapshot and consume any gas remaining. Additionally
+	// when we're in homestead this also counts for code storage gas errors.
+	if err != nil && (params.IsHomestead(env.BlockNumber()) || err != vm.CodeStoreOutOfGasError) {
+		contract.UseGas(contract.Gas)
+
+		env.SetSnapshot(snapshotPreTransfer)
+	}
+
 	return ret, addr, err
 }
 
@@ -131,32 +144,27 @@ func execDelegateCall(env vm.Environment, caller vm.ContractRef, originAddr, toA
 		return nil, common.Address{}, vm.DepthError
 	}
 
-	if !env.CanTransfer(*originAddr, value) {
-		caller.ReturnGas(gas, gasPrice)
-		return nil, common.Address{}, ValueTransferErr("insufficient funds to transfer value. Req %v, has %v", value, env.Db().GetBalance(caller.Address()))
-	}
-
 	snapshot := env.MakeSnapshot()
 
-	var (
-		//from = env.Db().GetAccount(*originAddr)
-		to vm.Account
-	)
+	var to vm.Account
 	if !env.Db().Exist(*toAddr) {
 		to = env.Db().CreateAccount(*toAddr)
 	} else {
 		to = env.Db().GetAccount(*toAddr)
 	}
 
-	contract := vm.NewContract(caller, to, value, gas, gasPrice)
+	// Iinitialise a new contract and make initialise the delegate values
+	contract := vm.NewContract(caller, to, value, gas, gasPrice).AsDelegate()
 	contract.SetCallCode(codeAddr, code)
-	contract.DelegateCall = true
+	defer contract.Finalise()
 
 	ret, err = evm.Run(contract, input)
-
 	if err != nil {
-		env.SetSnapshot(snapshot) //env.Db().Set(snapshot)
+		contract.UseGas(contract.Gas)
+
+		env.SetSnapshot(snapshot)
 	}
+
 	return ret, addr, err
 }
 
diff --git a/core/state/dump.go b/core/state/dump.go
index cff9c50aa..8eb03e8e4 100644
--- a/core/state/dump.go
+++ b/core/state/dump.go
@@ -28,6 +28,7 @@ type Account struct {
 	Nonce    uint64            `json:"nonce"`
 	Root     string            `json:"root"`
 	CodeHash string            `json:"codeHash"`
+	Code     string            `json:"code"`
 	Storage  map[string]string `json:"storage"`
 }
 
@@ -47,7 +48,7 @@ func (self *StateDB) RawDump() World {
 		addr := self.trie.GetKey(it.Key)
 		stateObject, _ := DecodeObject(common.BytesToAddress(addr), self.db, it.Value)
 
-		account := Account{Balance: stateObject.balance.String(), Nonce: stateObject.nonce, Root: common.Bytes2Hex(stateObject.Root()), CodeHash: common.Bytes2Hex(stateObject.codeHash)}
+		account := Account{Balance: stateObject.balance.String(), Nonce: stateObject.nonce, Root: common.Bytes2Hex(stateObject.Root()), CodeHash: common.Bytes2Hex(stateObject.codeHash), Code: common.Bytes2Hex(stateObject.Code())}
 		account.Storage = make(map[string]string)
 
 		storageIt := stateObject.trie.Iterator()
diff --git a/core/state/state_object.go b/core/state/state_object.go
index ebc9f8358..6095fc96a 100644
--- a/core/state/state_object.go
+++ b/core/state/state_object.go
@@ -211,11 +211,6 @@ func (c *StateObject) Address() common.Address {
 	return c.address
 }
 
-// Sets the address of the contract/account
-func (c *StateObject) SetAddress(addr common.Address) {
-	c.address = addr
-}
-
 func (self *StateObject) Trie() *trie.SecureTrie {
 	return self.trie
 }
@@ -247,7 +242,7 @@ func (self *StateObject) Nonce() uint64 {
 // as a vm.Account interface that also satisfies the vm.ContractRef
 // interface. Interfaces are awesome.
 func (self *StateObject) Value() *big.Int {
-	return nil
+	panic("Value on StateObject should never be called")
 }
 
 func (self *StateObject) EachStorage(cb func(key, value []byte)) {
diff --git a/core/state/statedb.go b/core/state/statedb.go
index e1dde84d1..22ffa36a0 100644
--- a/core/state/statedb.go
+++ b/core/state/statedb.go
@@ -87,18 +87,6 @@ func (self *StateDB) GetLogs(hash common.Hash) vm.Logs {
 	return self.logs[hash]
 }
 
-func (self *StateDB) GetAllLogs() *map[common.Hash]vm.Logs {
-	copy := make(map[common.Hash]vm.Logs, len(self.logs))
-	for k, v := range self.logs {
-		copy[k] = v
-	}
-	return &copy
-}
-
-func (self *StateDB) SetAllLogs(logs *map[common.Hash]vm.Logs) {
-	self.logs = *logs
-}
-
 func (self *StateDB) Logs() vm.Logs {
 	var logs vm.Logs
 	for _, lgs := range self.logs {
@@ -107,11 +95,6 @@ func (self *StateDB) Logs() vm.Logs {
 	return logs
 }
 
-// TODO: this may not be the most proper thing
-func (self *StateDB) GetDB() ethdb.Database {
-	return self.db
-}
-
 func (self *StateDB) AddRefund(gas *big.Int) {
 	self.refund.Add(self.refund, gas)
 }
diff --git a/core/state_transition.go b/core/state_transition.go
index 0cd226262..52a46c63d 100644
--- a/core/state_transition.go
+++ b/core/state_transition.go
@@ -21,7 +21,6 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
@@ -225,38 +224,24 @@ func (self *StateTransition) transitionDb() (ret []byte, usedGas *big.Int, err e
 	}
 
 	vmenv := self.env
-	snapshot := vmenv.MakeSnapshot()
-	var addr common.Address
+	//var addr common.Address
 	if contractCreation {
-		ret, addr, err = vmenv.Create(sender, self.data, self.gas, self.gasPrice, self.value)
-		if err == nil {
-			dataGas := big.NewInt(int64(len(ret)))
-			dataGas.Mul(dataGas, params.CreateDataGas)
-			if err := self.useGas(dataGas); err == nil {
-				self.state.SetCode(addr, ret)
-			} else {
-				if homestead {
-					// rollback all contract creation changes except for
-					// sender's incremented account nonce and gas usage
-					// TODO: fucking gas hack... verify potential DoS vuln
-					accNonce := vmenv.Db().GetNonce(sender.Address())
-					logs := vmenv.Db().(*state.StateDB).GetAllLogs()
-					vmenv.SetSnapshot(snapshot)
-					vmenv.Db().SetNonce(sender.Address(), accNonce)
-					vmenv.Db().(*state.StateDB).SetAllLogs(logs)
-					self.gas = Big0
-
-				}
-				ret = nil // does not affect consensus but useful for StateTests validations
-				glog.V(logger.Core).Infoln("Insufficient gas for creating code. Require", dataGas, "and have", self.gas)
-			}
+		ret, _, err = vmenv.Create(sender, self.data, self.gas, self.gasPrice, self.value)
+		if homestead && err == vm.CodeStoreOutOfGasError {
+			self.gas = Big0
+		}
+
+		if err != nil {
+			ret = nil
+			glog.V(logger.Core).Infoln("VM create err:", err)
 		}
-		glog.V(logger.Core).Infoln("VM create err:", err)
 	} else {
 		// Increment the nonce for the next transaction
 		self.state.SetNonce(sender.Address(), self.state.GetNonce(sender.Address())+1)
 		ret, err = vmenv.Call(sender, self.to().Address(), self.data, self.gas, self.gasPrice, self.value)
-		glog.V(logger.Core).Infoln("VM call err:", err)
+		if err != nil {
+			glog.V(logger.Core).Infoln("VM call err:", err)
+		}
 	}
 
 	if err != nil && IsValueTransferErr(err) {
diff --git a/core/transaction_pool.go b/core/tx_pool.go
index a815c9ef0..b8fb4cd35 100644
--- a/core/transaction_pool.go
+++ b/core/tx_pool.go
@@ -71,6 +71,8 @@ type TxPool struct {
 	mu           sync.RWMutex
 	pending      map[common.Hash]*types.Transaction // processable transactions
 	queue        map[common.Address]map[common.Hash]*types.Transaction
+
+	homestead bool
 }
 
 func NewTxPool(eventMux *event.TypeMux, currentStateFn stateFn, gasLimitFn func() *big.Int) *TxPool {
@@ -86,6 +88,7 @@ func NewTxPool(eventMux *event.TypeMux, currentStateFn stateFn, gasLimitFn func(
 		localTx:      newTxSet(),
 		events:       eventMux.Subscribe(ChainHeadEvent{}, GasPriceChanged{}, RemovedTransactionEvent{}),
 	}
+
 	go pool.eventLoop()
 
 	return pool
@@ -99,6 +102,10 @@ func (pool *TxPool) eventLoop() {
 		switch ev := ev.Data.(type) {
 		case ChainHeadEvent:
 			pool.mu.Lock()
+			if ev.Block != nil && params.IsHomestead(ev.Block.Number()) {
+				pool.homestead = true
+			}
+
 			pool.resetState()
 			pool.mu.Unlock()
 		case GasPriceChanged:
@@ -211,12 +218,6 @@ func (pool *TxPool) SetLocal(tx *types.Transaction) {
 // validateTx checks whether a transaction is valid according
 // to the consensus rules.
 func (pool *TxPool) validateTx(tx *types.Transaction) error {
-	// Validate sender
-	var (
-		from common.Address
-		err  error
-	)
-
 	local := pool.localTx.contains(tx.Hash())
 	// Drop transactions under our own minimal accepted gas price
 	if !local && pool.minGasPrice.Cmp(tx.GasPrice()) > 0 {
@@ -228,15 +229,7 @@ func (pool *TxPool) validateTx(tx *types.Transaction) error {
 		return err
 	}
 
-	homestead := params.IsHomestead(GetHeadBlockNum(currentState.GetDB()))
-
-	// Validate the transaction sender and it's sig. Throw
-	// if the from fields is invalid.
-	if homestead {
-		from, err = tx.From()
-	} else {
-		from, err = tx.FromFrontier()
-	}
+	from, err := tx.From()
 	if err != nil {
 		return ErrInvalidSender
 	}
@@ -271,8 +264,7 @@ func (pool *TxPool) validateTx(tx *types.Transaction) error {
 		return ErrInsufficientFunds
 	}
 
-	// Should supply enough intrinsic gas
-	intrGas := IntrinsicGas(tx.Data(), MessageCreatesContract(tx), homestead)
+	intrGas := IntrinsicGas(tx.Data(), MessageCreatesContract(tx), pool.homestead)
 	if tx.Gas().Cmp(intrGas) < 0 {
 		return ErrIntrinsicGas
 	}
diff --git a/core/transaction_pool_test.go b/core/tx_pool_test.go
index 811e40111..811e40111 100644
--- a/core/transaction_pool_test.go
+++ b/core/tx_pool_test.go
diff --git a/core/types/transaction.go b/core/types/transaction.go
index af952e450..0c9c1ce18 100644
--- a/core/types/transaction.go
+++ b/core/types/transaction.go
@@ -157,7 +157,14 @@ func (tx *Transaction) Size() common.StorageSize {
 	return common.StorageSize(c)
 }
 
-// From() caches the address, allowing it to be used regardless of
+// From returns the address derived from the signature (V, R, S) using secp256k1
+// eliptic curve and an error if it failed deriving or upon an incorrect
+// signature.
+//
+// From Uses the homestead consensus rules to determine whether the signature is
+// valid.
+//
+// From caches the address, allowing it to be used regardless of
 // Frontier / Homestead. however, the first time called it runs
 // signature validations, so we need two versions. This makes it
 // easier to ensure backwards compatibility of things like package rpc
@@ -168,6 +175,20 @@ func (tx *Transaction) From() (common.Address, error) {
 	return doFrom(tx, true)
 }
 
+// FromFrontier returns the address derived from the signature (V, R, S) using
+// secp256k1 eliptic curve and an error if it failed deriving or upon an
+// incorrect signature.
+//
+// FromFrantier uses the frontier consensus rules to determine whether the
+// signature is valid.
+//
+// FromFrontier caches the address, allowing it to be used regardless of
+// Frontier / Homestead. however, the first time called it runs
+// signature validations, so we need two versions. This makes it
+// easier to ensure backwards compatibility of things like package rpc
+// where eth_getblockbynumber uses tx.From() and needs to work for
+// both txs before and after the first homestead block. Signatures
+// valid in homestead are a subset of valid ones in Frontier)
 func (tx *Transaction) FromFrontier() (common.Address, error) {
 	return doFrom(tx, false)
 }
diff --git a/core/vm/contract.go b/core/vm/contract.go
index dac81a529..d23995218 100644
--- a/core/vm/contract.go
+++ b/core/vm/contract.go
@@ -26,7 +26,6 @@ import (
 type ContractRef interface {
 	ReturnGas(*big.Int, *big.Int)
 	Address() common.Address
-	SetAddress(common.Address)
 	Value() *big.Int
 	SetCode([]byte)
 	EachStorage(cb func(key, value []byte))
@@ -35,8 +34,12 @@ type ContractRef interface {
 // Contract represents an ethereum contract in the state database. It contains
 // the the contract code, calling arguments. Contract implements ContractRef
 type Contract struct {
-	caller ContractRef
-	self   ContractRef
+	// CallerAddress is the result of the caller which initialised this
+	// contract. However when the "call method" is delegated this value
+	// needs to be initialised to that of the caller's caller.
+	CallerAddress common.Address
+	caller        ContractRef
+	self          ContractRef
 
 	jumpdests destinations // result of JUMPDEST analysis.
 
@@ -51,9 +54,9 @@ type Contract struct {
 	DelegateCall bool
 }
 
-// Create a new context for the given data items.
+// NewContract returns a new contract environment for the execution of EVM.
 func NewContract(caller ContractRef, object ContractRef, value, gas, price *big.Int) *Contract {
-	c := &Contract{caller: caller, self: object, Args: nil}
+	c := &Contract{CallerAddress: caller.Address(), caller: caller, self: object, Args: nil}
 
 	if parent, ok := caller.(*Contract); ok {
 		// Reuse JUMPDEST analysis from parent context if available.
@@ -74,6 +77,16 @@ func NewContract(caller ContractRef, object ContractRef, value, gas, price *big.
 	return c
 }
 
+// AsDelegate sets the contract to be a delegate call and returns the current
+// contract (for chaining calls)
+func (c *Contract) AsDelegate() *Contract {
+	c.DelegateCall = true
+	// NOTE: caller must, at all times be a contract. It should never happen
+	// that caller is something other than a Contract.
+	c.CallerAddress = c.caller.(*Contract).CallerAddress
+	return c
+}
+
 // GetOp returns the n'th element in the contract's byte array
 func (c *Contract) GetOp(n uint64) OpCode {
 	return OpCode(c.GetByte(n))
@@ -88,13 +101,19 @@ func (c *Contract) GetByte(n uint64) byte {
 	return 0
 }
 
-// Return returns the given ret argument and returns any remaining gas to the
-// caller
-func (c *Contract) Return(ret []byte) []byte {
+// Caller returns the caller of the contract.
+//
+// Caller will recursively call caller when the contract is a delegate
+// call, including that of caller's caller.
+func (c *Contract) Caller() common.Address {
+	return c.CallerAddress
+}
+
+// Finalise finalises the contract and returning any remaining gas to the original
+// caller.
+func (c *Contract) Finalise() {
 	// Return the remaining gas to the caller
 	c.caller.ReturnGas(c.Gas, c.Price)
-
-	return ret
 }
 
 // UseGas attempts the use gas and subtracts it and returns true on success
@@ -118,11 +137,6 @@ func (c *Contract) Address() common.Address {
 	return c.self.Address()
 }
 
-// SetAddress sets the contracts address
-func (c *Contract) SetAddress(addr common.Address) {
-	c.self.SetAddress(addr)
-}
-
 // Value returns the contracts value (sent to it from it's caller)
 func (c *Contract) Value() *big.Int {
 	return c.value
diff --git a/core/vm/environment.go b/core/vm/environment.go
index dc60af2ca..a58e3ba2b 100644
--- a/core/vm/environment.go
+++ b/core/vm/environment.go
@@ -121,7 +121,6 @@ type Account interface {
 	SetNonce(uint64)
 	Balance() *big.Int
 	Address() common.Address
-	SetAddress(common.Address)
 	ReturnGas(*big.Int, *big.Int)
 	SetCode([]byte)
 	EachStorage(cb func(key, value []byte))
diff --git a/core/vm/instructions.go b/core/vm/instructions.go
index 9d3d4e6fe..26f7671ff 100644
--- a/core/vm/instructions.go
+++ b/core/vm/instructions.go
@@ -337,13 +337,7 @@ func opOrigin(instr instruction, pc *uint64, env Environment, contract *Contract
 }
 
 func opCaller(instr instruction, pc *uint64, env Environment, contract *Contract, memory *Memory, stack *stack) {
-	var bigAddr *big.Int
-	if contract.DelegateCall {
-		bigAddr = env.Origin().Big()
-	} else {
-		bigAddr = contract.caller.Address().Big()
-	}
-	stack.push(bigAddr)
+	stack.push(contract.Caller().Big())
 }
 
 func opCallValue(instr instruction, pc *uint64, env Environment, contract *Contract, memory *Memory, stack *stack) {
@@ -514,6 +508,25 @@ func opGas(instr instruction, pc *uint64, env Environment, contract *Contract, m
 }
 
 func opCreate(instr instruction, pc *uint64, env Environment, contract *Contract, memory *Memory, stack *stack) {
+	var (
+		value        = stack.pop()
+		offset, size = stack.pop(), stack.pop()
+		input        = memory.Get(offset.Int64(), size.Int64())
+		gas          = new(big.Int).Set(contract.Gas)
+	)
+	contract.UseGas(contract.Gas)
+	_, addr, suberr := env.Create(contract, input, gas, contract.Price, value)
+	// Push item on the stack based on the returned error. If the ruleset is
+	// homestead we must check for CodeStoreOutOfGasError (homestead only
+	// rule) and treat as an error, if the ruleset is frontier we must
+	// ignore this error and pretend the operation was successful.
+	if params.IsHomestead(env.BlockNumber()) && suberr == CodeStoreOutOfGasError {
+		stack.push(new(big.Int))
+	} else if suberr != nil && suberr != CodeStoreOutOfGasError {
+		stack.push(new(big.Int))
+	} else {
+		stack.push(addr.Big())
+	}
 }
 
 func opCall(instr instruction, pc *uint64, env Environment, contract *Contract, memory *Memory, stack *stack) {
diff --git a/core/vm/jit.go b/core/vm/jit.go
index 1aa7d7ef2..504aab523 100644
--- a/core/vm/jit.go
+++ b/core/vm/jit.go
@@ -275,6 +275,11 @@ func CompileProgram(program *Program) (err error) {
 			program.addInstr(op, pc, opGas, nil)
 		case CREATE:
 			program.addInstr(op, pc, opCreate, nil)
+		case DELEGATECALL:
+			// Instruction added regardless of homestead phase.
+			// Homestead (and execution of the opcode) is checked during
+			// runtime.
+			program.addInstr(op, pc, opDelegateCall, nil)
 		case CALL:
 			program.addInstr(op, pc, opCall, nil)
 		case CALLCODE:
@@ -317,10 +322,14 @@ func runProgram(program *Program, pcstart uint64, mem *Memory, stack *stack, env
 		}()
 	}
 
+	homestead := params.IsHomestead(env.BlockNumber())
 	for pc < uint64(len(program.instructions)) {
 		instrCount++
 
 		instr := program.instructions[pc]
+		if instr.Op() == DELEGATECALL && !homestead {
+			return nil, fmt.Errorf("Invalid opcode 0x%x", instr.Op())
+		}
 
 		ret, err := instr.do(program, &pc, env, contract, mem, stack)
 		if err != nil {
@@ -328,13 +337,13 @@ func runProgram(program *Program, pcstart uint64, mem *Memory, stack *stack, env
 		}
 
 		if instr.halts() {
-			return contract.Return(ret), nil
+			return ret, nil
 		}
 	}
 
 	contract.Input = nil
 
-	return contract.Return(nil), nil
+	return nil, nil
 }
 
 // validDest checks if the given distination is a valid one given the
@@ -457,7 +466,6 @@ func jitCalculateGasAndSize(env Environment, contract *Contract, instr instructi
 		gas.Add(gas, stack.data[stack.len()-1])
 
 		if op == CALL {
-			//if env.Db().GetStateObject(common.BigToAddress(stack.data[stack.len()-2])) == nil {
 			if !env.Db().Exist(common.BigToAddress(stack.data[stack.len()-2])) {
 				gas.Add(gas, params.CallNewAccountGas)
 			}
@@ -471,6 +479,13 @@ func jitCalculateGasAndSize(env Environment, contract *Contract, instr instructi
 		y := calcMemSize(stack.data[stack.len()-4], stack.data[stack.len()-5])
 
 		newMemSize = common.BigMax(x, y)
+	case DELEGATECALL:
+		gas.Add(gas, stack.data[stack.len()-1])
+
+		x := calcMemSize(stack.data[stack.len()-5], stack.data[stack.len()-6])
+		y := calcMemSize(stack.data[stack.len()-3], stack.data[stack.len()-4])
+
+		newMemSize = common.BigMax(x, y)
 	}
 	quadMemGas(mem, newMemSize, gas)
 
diff --git a/core/vm/jit_test.go b/core/vm/jit_test.go
index 8c50ed0f5..e8e078a46 100644
--- a/core/vm/jit_test.go
+++ b/core/vm/jit_test.go
@@ -127,6 +127,8 @@ type account struct{}
 
 func (account) SubBalance(amount *big.Int)             {}
 func (account) AddBalance(amount *big.Int)             {}
+func (account) SetAddress(common.Address)              {}
+func (account) Value() *big.Int                        { return nil }
 func (account) SetBalance(*big.Int)                    {}
 func (account) SetNonce(uint64)                        {}
 func (account) Balance() *big.Int                      { return nil }
@@ -206,3 +208,6 @@ func (self *Env) CallCode(caller ContractRef, addr common.Address, data []byte,
 func (self *Env) Create(caller ContractRef, data []byte, gas, price, value *big.Int) ([]byte, common.Address, error) {
 	return nil, common.Address{}, nil
 }
+func (self *Env) DelegateCall(me ContractRef, addr common.Address, data []byte, gas, price *big.Int) ([]byte, error) {
+	return nil, nil
+}
diff --git a/core/vm/jump_table.go b/core/vm/jump_table.go
index 222c93854..37d7bb160 100644
--- a/core/vm/jump_table.go
+++ b/core/vm/jump_table.go
@@ -1,13 +1,29 @@
 package vm
 
-import "math/big"
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/params"
+)
 
 type jumpPtr struct {
 	fn    instrFn
 	valid bool
 }
 
-var jumpTable [256]jumpPtr
+type vmJumpTable [256]jumpPtr
+
+func (jt vmJumpTable) init(blockNumber *big.Int) {
+	// when initialising a new VM execution we must first check the homestead
+	// changes.
+	if params.IsHomestead(blockNumber) {
+		jumpTable[DELEGATECALL] = jumpPtr{opDelegateCall, true}
+	} else {
+		jumpTable[DELEGATECALL] = jumpPtr{nil, false}
+	}
+}
+
+var jumpTable vmJumpTable
 
 func init() {
 	jumpTable[ADD] = jumpPtr{opAdd, true}
@@ -62,10 +78,9 @@ func init() {
 	jumpTable[PC] = jumpPtr{nil, true}
 	jumpTable[MSIZE] = jumpPtr{opMsize, true}
 	jumpTable[GAS] = jumpPtr{opGas, true}
-	jumpTable[CREATE] = jumpPtr{nil, true}
+	jumpTable[CREATE] = jumpPtr{opCreate, true}
 	jumpTable[CALL] = jumpPtr{opCall, true}
 	jumpTable[CALLCODE] = jumpPtr{opCallCode, true}
-	jumpTable[DELEGATECALL] = jumpPtr{opDelegateCall, true}
 	jumpTable[LOG0] = jumpPtr{makeLog(0), true}
 	jumpTable[LOG1] = jumpPtr{makeLog(1), true}
 	jumpTable[LOG2] = jumpPtr{makeLog(2), true}
diff --git a/core/vm/jump_table_test.go b/core/vm/jump_table_test.go
new file mode 100644
index 000000000..98d34bef2
--- /dev/null
+++ b/core/vm/jump_table_test.go
@@ -0,0 +1,24 @@
+package vm
+
+import (
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/params"
+)
+
+func TestInit(t *testing.T) {
+	params.HomesteadBlock = big.NewInt(1)
+
+	jumpTable.init(big.NewInt(0))
+	if jumpTable[DELEGATECALL].valid {
+		t.Error("Expected DELEGATECALL not to be present")
+	}
+
+	for _, n := range []int64{1, 2, 100} {
+		jumpTable.init(big.NewInt(n))
+		if !jumpTable[DELEGATECALL].valid {
+			t.Error("Expected DELEGATECALL to be present for block", n)
+		}
+	}
+}
diff --git a/core/vm/opcodes.go b/core/vm/opcodes.go
index 00593ae95..7d861f1de 100644
--- a/core/vm/opcodes.go
+++ b/core/vm/opcodes.go
@@ -404,6 +404,7 @@ var stringToOp = map[string]OpCode{
 	"CALLDATALOAD": CALLDATALOAD,
 	"CALLDATASIZE": CALLDATASIZE,
 	"CALLDATACOPY": CALLDATACOPY,
+	"DELEGATECALL": DELEGATECALL,
 	"CODESIZE":     CODESIZE,
 	"CODECOPY":     CODECOPY,
 	"GASPRICE":     GASPRICE,
diff --git a/core/vm/vm.go b/core/vm/vm.go
index 863b2cc0d..320135ff2 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -35,6 +35,9 @@ type Vm struct {
 
 // New returns a new Vm
 func New(env Environment) *Vm {
+	// init the jump table. Also prepares the homestead changes
+	jumpTable.init(env.BlockNumber())
+
 	return &Vm{env: env}
 }
 
@@ -43,16 +46,6 @@ func (self *Vm) Run(contract *Contract, input []byte) (ret []byte, err error) {
 	self.env.SetDepth(self.env.Depth() + 1)
 	defer self.env.SetDepth(self.env.Depth() - 1)
 
-	// User defer pattern to check for an error and, based on the error being nil or not, use all gas and return.
-	defer func() {
-		if err != nil {
-			// In case of a VM exception (known exceptions) all gas consumed (panics NOT included).
-			contract.UseGas(contract.Gas)
-
-			ret = contract.Return(nil)
-		}
-	}()
-
 	if contract.CodeAddr != nil {
 		if p := Precompiled[contract.CodeAddr.Str()]; p != nil {
 			return self.RunPrecompiled(p, input, contract)
@@ -61,7 +54,7 @@ func (self *Vm) Run(contract *Contract, input []byte) (ret []byte, err error) {
 
 	// Don't bother with the execution if there's no code.
 	if len(contract.Code) == 0 {
-		return contract.Return(nil), nil
+		return nil, nil
 	}
 
 	var (
@@ -199,46 +192,17 @@ func (self *Vm) Run(contract *Contract, input []byte) (ret []byte, err error) {
 
 						continue
 					}
-				case CREATE:
-					var (
-						value        = stack.pop()
-						offset, size = stack.pop(), stack.pop()
-						input        = mem.Get(offset.Int64(), size.Int64())
-						gas          = new(big.Int).Set(contract.Gas)
-						addr         common.Address
-						ret          []byte
-						suberr       error
-					)
-					contract.UseGas(contract.Gas)
-					ret, addr, suberr = self.env.Create(contract, input, gas, contract.Price, value)
-					if suberr != nil {
-						stack.push(new(big.Int))
-					} else {
-						// gas < len(ret) * Createinstr.dataGas == NO_CODE
-						dataGas := big.NewInt(int64(len(ret)))
-						dataGas.Mul(dataGas, params.CreateDataGas)
-						if contract.UseGas(dataGas) {
-							self.env.Db().SetCode(addr, ret)
-						} else {
-							if params.IsHomestead(self.env.BlockNumber()) {
-								stack.push(new(big.Int))
-								return nil, CodeStoreOutOfGasError
-							}
-						}
-						stack.push(addr.Big())
-					}
-
 				case RETURN:
 					offset, size := stack.pop(), stack.pop()
 					ret := mem.GetPtr(offset.Int64(), size.Int64())
 
-					return contract.Return(ret), nil
+					return ret, nil
 				case SUICIDE:
 					opSuicide(instruction{}, nil, self.env, contract, mem, stack)
 
 					fallthrough
 				case STOP: // Stop the contract
-					return contract.Return(nil), nil
+					return nil, nil
 				}
 			}
 		} else {
@@ -359,7 +323,6 @@ func calculateGasAndSize(env Environment, contract *Contract, caller ContractRef
 		gas.Add(gas, stack.data[stack.len()-1])
 
 		if op == CALL {
-			//if env.Db().GetStateObject(common.BigToAddress(stack.data[stack.len()-2])) == nil {
 			if !env.Db().Exist(common.BigToAddress(stack.data[stack.len()-2])) {
 				gas.Add(gas, params.CallNewAccountGas)
 			}
@@ -392,7 +355,7 @@ func (self *Vm) RunPrecompiled(p *PrecompiledAccount, input []byte, contract *Co
 	if contract.UseGas(gas) {
 		ret = p.Call(input)
 
-		return contract.Return(ret), nil
+		return ret, nil
 	} else {
 		return nil, OutOfGasError
 	}