consensus, core/*, params: metropolis preparation refactor

This commit is a preparation for the upcoming metropolis hardfork. It
prepares the state, core and vm packages such that integration with
metropolis becomes less of a hassle.

* Difficulty calculation requires header instead of individual
  parameters
* statedb.StartRecord renamed to statedb.Prepare and added Finalise
  method required by metropolis, which removes unwanted accounts from
  the state (i.e. selfdestruct)
* State keeps record of destructed objects (in addition to dirty
  objects)
* core/vm pre-compiles may now return errors
* core/vm pre-compiles gas check now take the full byte slice as argument
  instead of just the size
* core/vm now keeps several hard-fork instruction tables instead of a
  single instruction table and removes the need for hard-fork checks in
  the instructions
* core/vm contains a empty restruction function which is added in
  preparation of metropolis write-only mode operations
* Adds the bn256 curve
* Adds and sets the metropolis chain config block parameters (2^64-1)

core/vm/contracts.go

@@ -18,6 +18,7 @@ package vm
 
 import (
 	"crypto/sha256"
+	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -27,15 +28,17 @@ import (
 	"golang.org/x/crypto/ripemd160"
 )
 
+var errBadPrecompileInput = errors.New("bad pre compile input")
+
 // Precompiled contract is the basic interface for native Go contracts. The implementation
 // requires a deterministic gas count based on the input size of the Run method of the
 // contract.
 type PrecompiledContract interface {
-	RequiredGas(inputSize int) uint64 // RequiredPrice calculates the contract gas use
-	Run(input []byte) []byte          // Run runs the precompiled contract
+	RequiredGas(input []byte) uint64  // RequiredPrice calculates the contract gas use
+	Run(input []byte) ([]byte, error) // Run runs the precompiled contract
 }
 
-// Precompiled contains the default set of ethereum contracts
+// PrecompiledContracts contains the default set of ethereum contracts
 var PrecompiledContracts = map[common.Address]PrecompiledContract{
 	common.BytesToAddress([]byte{1}): &ecrecover{},
 	common.BytesToAddress([]byte{2}): &sha256hash{},
@@ -45,11 +48,9 @@ var PrecompiledContracts = map[common.Address]PrecompiledContract{
 
 // RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go
 func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contract) (ret []byte, err error) {
-	gas := p.RequiredGas(len(input))
+	gas := p.RequiredGas(input)
 	if contract.UseGas(gas) {
-		ret = p.Run(input)
-
-		return ret, nil
+		return p.Run(input)
 	} else {
 		return nil, ErrOutOfGas
 	}
@@ -58,11 +59,11 @@ func RunPrecompiledContract(p PrecompiledContract, input []byte, contract *Contr
 // ECRECOVER implemented as a native contract
 type ecrecover struct{}
 
-func (c *ecrecover) RequiredGas(inputSize int) uint64 {
+func (c *ecrecover) RequiredGas(input []byte) uint64 {
 	return params.EcrecoverGas
 }
 
-func (c *ecrecover) Run(in []byte) []byte {
+func (c *ecrecover) Run(in []byte) ([]byte, error) {
 	const ecRecoverInputLength = 128
 
 	in = common.RightPadBytes(in, ecRecoverInputLength)
@@ -76,18 +77,18 @@ func (c *ecrecover) Run(in []byte) []byte {
 	// tighter sig s values in homestead only apply to tx sigs
 	if !allZero(in[32:63]) || !crypto.ValidateSignatureValues(v, r, s, false) {
 		log.Trace("ECRECOVER error: v, r or s value invalid")
-		return nil
+		return nil, nil
 	}
 	// v needs to be at the end for libsecp256k1
 	pubKey, err := crypto.Ecrecover(in[:32], append(in[64:128], v))
 	// make sure the public key is a valid one
 	if err != nil {
 		log.Trace("ECRECOVER failed", "err", err)
-		return nil
+		return nil, nil
 	}
 
 	// the first byte of pubkey is bitcoin heritage
-	return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32)
+	return common.LeftPadBytes(crypto.Keccak256(pubKey[1:])[12:], 32), nil
 }
 
 // SHA256 implemented as a native contract
@@ -97,12 +98,12 @@ type sha256hash struct{}
 //
 // This method does not require any overflow checking as the input size gas costs
 // required for anything significant is so high it's impossible to pay for.
-func (c *sha256hash) RequiredGas(inputSize int) uint64 {
-	return uint64(inputSize+31)/32*params.Sha256WordGas + params.Sha256Gas
+func (c *sha256hash) RequiredGas(input []byte) uint64 {
+	return uint64(len(input)+31)/32*params.Sha256WordGas + params.Sha256Gas
 }
-func (c *sha256hash) Run(in []byte) []byte {
+func (c *sha256hash) Run(in []byte) ([]byte, error) {
 	h := sha256.Sum256(in)
-	return h[:]
+	return h[:], nil
 }
 
 // RIPMED160 implemented as a native contract
@@ -112,13 +113,13 @@ type ripemd160hash struct{}
 //
 // This method does not require any overflow checking as the input size gas costs
 // required for anything significant is so high it's impossible to pay for.
-func (c *ripemd160hash) RequiredGas(inputSize int) uint64 {
-	return uint64(inputSize+31)/32*params.Ripemd160WordGas + params.Ripemd160Gas
+func (c *ripemd160hash) RequiredGas(input []byte) uint64 {
+	return uint64(len(input)+31)/32*params.Ripemd160WordGas + params.Ripemd160Gas
 }
-func (c *ripemd160hash) Run(in []byte) []byte {
+func (c *ripemd160hash) Run(in []byte) ([]byte, error) {
 	ripemd := ripemd160.New()
 	ripemd.Write(in)
-	return common.LeftPadBytes(ripemd.Sum(nil), 32)
+	return common.LeftPadBytes(ripemd.Sum(nil), 32), nil
 }
 
 // data copy implemented as a native contract
@@ -128,9 +129,9 @@ type dataCopy struct{}
 //
 // This method does not require any overflow checking as the input size gas costs
 // required for anything significant is so high it's impossible to pay for.
-func (c *dataCopy) RequiredGas(inputSize int) uint64 {
-	return uint64(inputSize+31)/32*params.IdentityWordGas + params.IdentityGas
+func (c *dataCopy) RequiredGas(input []byte) uint64 {
+	return uint64(len(input)+31)/32*params.IdentityWordGas + params.IdentityGas
 }
-func (c *dataCopy) Run(in []byte) []byte {
-	return in
+func (c *dataCopy) Run(in []byte) ([]byte, error) {
+	return in, nil
 }