neoneo-go/pkg/core/blockchain.go
dauTT 095653af23 Implement rpc server method: sendrawtransaction (#174)
* Added new config attributes: 'SecondsPerBlock','LowPriorityThreshold'

* Added new files:

* Added new method: CompareTo

* Fixed empty Slice case

* Added new methods: LessThan, GreaterThan, Equal, CompareTo

* Added new method: InputIntersection

* Added MaxTransactionSize, GroupOutputByAssetID

* Added ned method: ScriptHash

* Added new method: IsDoubleSpend

* Refactor blockchainer, Added Feer interface, Verify and GetMemPool method

* 1) Added MemPool
2) Added new methods to satisfy the blockchainer interface: IsLowPriority, Verify, GetMemPool

* Added new methods: RelayTxn, RelayDirectly

* Fixed tests

* Implemented RPC server method sendrawtransaction

* Refactor getrawtransaction, sendrawtransaction in separate methods

* Moved 'secondsPerBlock' to config file

* Implemented Kim suggestions:
1) Fixed data race issues
2) refactor Verify method
3) Get rid of unused InputIntersection  method due to refactoring Verify method
4) Fixed bug in https://github.com/CityOfZion/neo-go/pull/174#discussion_r264108135
5) minor simplications of the code

* Fixed minor issues related to

1) space
2) getter methods do not need pointer on the receiver
3) error message
4) refactoring  CompareTo method in uint256.go

* Fixed small issues

* Use sync.RWMutex instead of sync.Mutex

* Refined (R)Lock/(R)Unlock

* return error instead of bool in Verify methods
2019-03-20 12:30:05 +00:00

935 lines
25 KiB
Go

package core
import (
"bytes"
"context"
"encoding/binary"
"fmt"
"math"
"sync/atomic"
"time"
"github.com/CityOfZion/neo-go/config"
"github.com/CityOfZion/neo-go/pkg/core/storage"
"github.com/CityOfZion/neo-go/pkg/core/transaction"
"github.com/CityOfZion/neo-go/pkg/util"
"github.com/pkg/errors"
log "github.com/sirupsen/logrus"
)
// tuning parameters
const (
headerBatchCount = 2000
version = "0.0.1"
)
var (
genAmount = []int{8, 7, 6, 5, 4, 3, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}
decrementInterval = 2000000
persistInterval = 1 * time.Second
)
// Blockchain represents the blockchain.
type Blockchain struct {
config config.ProtocolConfiguration
// Any object that satisfies the BlockchainStorer interface.
storage.Store
// Current index/height of the highest block.
// Read access should always be called by BlockHeight().
// Write access should only happen in persist().
blockHeight uint32
// Number of headers stored in the chain file.
storedHeaderCount uint32
blockCache *Cache
// All operation on headerList must be called from an
// headersOp to be routine safe.
headerList *HeaderHashList
// Only for operating on the headerList.
headersOp chan headersOpFunc
headersOpDone chan struct{}
// Whether we will verify received blocks.
verifyBlocks bool
memPool MemPool
}
type headersOpFunc func(headerList *HeaderHashList)
// NewBlockchain return a new blockchain object the will use the
// given Store as its underlying storage.
func NewBlockchain(ctx context.Context, s storage.Store, cfg config.ProtocolConfiguration) (*Blockchain, error) {
bc := &Blockchain{
config: cfg,
Store: s,
headersOp: make(chan headersOpFunc),
headersOpDone: make(chan struct{}),
blockCache: NewCache(),
verifyBlocks: false,
memPool: NewMemPool(50000),
}
go bc.run(ctx)
if err := bc.init(); err != nil {
return nil, err
}
return bc, nil
}
// GetBlockchainLevelDB returns blockchain based on configuration
func NewBlockchainLevelDB(ctx context.Context, cfg config.Config) (*Blockchain, error) {
store, err := storage.NewLevelDBStore(
ctx,
cfg.ApplicationConfiguration.DataDirectoryPath,
nil,
)
if err != nil {
return nil, err
}
return NewBlockchain(ctx, store, cfg.ProtocolConfiguration)
}
func (bc *Blockchain) init() error {
genesisBlock, err := createGenesisBlock(bc.config)
if err != nil {
return err
}
bc.headerList = NewHeaderHashList(genesisBlock.Hash())
// If we could not find the version in the Store, we know that there is nothing stored.
ver, err := storage.Version(bc.Store)
if err != nil {
log.Infof("no storage version found! creating genesis block")
if err = storage.PutVersion(bc.Store, version); err != nil {
return err
}
return bc.persistBlock(genesisBlock)
}
if ver != version {
return fmt.Errorf("storage version mismatch betweeen %s and %s", version, ver)
}
// At this point there was no version found in the storage which
// implies a creating fresh storage with the version specified
// and the genesis block as first block.
log.Infof("restoring blockchain with version: %s", version)
bHeight, err := storage.CurrentBlockHeight(bc.Store)
if err != nil {
return err
}
bc.blockHeight = bHeight
hashes, err := storage.HeaderHashes(bc.Store)
if err != nil {
return err
}
for _, hash := range hashes {
if !genesisBlock.Hash().Equals(hash) {
bc.headerList.Add(hash)
bc.storedHeaderCount++
}
}
currHeaderHeight, currHeaderHash, err := storage.CurrentHeaderHeight(bc.Store)
if err != nil {
return err
}
// There is a high chance that the Node is stopped before the next
// batch of 2000 headers was stored. Via the currentHeaders stored we can sync
// that with stored blocks.
if currHeaderHeight > bc.storedHeaderCount {
hash := currHeaderHash
targetHash := bc.headerList.Get(bc.headerList.Len() - 1)
headers := make([]*Header, 0)
for hash != targetHash {
header, err := bc.GetHeader(hash)
if err != nil {
return fmt.Errorf("could not get header %s: %s", hash, err)
}
headers = append(headers, header)
hash = header.PrevHash
}
headerSliceReverse(headers)
if err := bc.AddHeaders(headers...); err != nil {
return err
}
}
return nil
}
func (bc *Blockchain) run(ctx context.Context) {
persistTimer := time.NewTimer(persistInterval)
defer persistTimer.Stop()
for {
select {
case <-ctx.Done():
return
case op := <-bc.headersOp:
op(bc.headerList)
bc.headersOpDone <- struct{}{}
case <-persistTimer.C:
go bc.persist(ctx)
persistTimer.Reset(persistInterval)
}
}
}
// AddBlock processes the given block and will add it to the cache so it
// can be persisted.
func (bc *Blockchain) AddBlock(block *Block) error {
if !bc.blockCache.Has(block.Hash()) {
bc.blockCache.Add(block.Hash(), block)
}
headerLen := bc.headerListLen()
if int(block.Index-1) >= headerLen {
return nil
}
if int(block.Index) == headerLen {
if bc.verifyBlocks && !block.Verify(false) {
return fmt.Errorf("block %s is invalid", block.Hash())
}
return bc.AddHeaders(block.Header())
}
return nil
}
// AddHeaders will process the given headers and add them to the
// HeaderHashList.
func (bc *Blockchain) AddHeaders(headers ...*Header) (err error) {
var (
start = time.Now()
batch = bc.Batch()
)
bc.headersOp <- func(headerList *HeaderHashList) {
for _, h := range headers {
if int(h.Index-1) >= headerList.Len() {
err = fmt.Errorf(
"height of received header %d is higher then the current header %d",
h.Index, headerList.Len(),
)
return
}
if int(h.Index) < headerList.Len() {
continue
}
if !h.Verify() {
err = fmt.Errorf("header %v is invalid", h)
return
}
if err = bc.processHeader(h, batch, headerList); err != nil {
return
}
}
if batch.Len() > 0 {
if err = bc.PutBatch(batch); err != nil {
return
}
log.WithFields(log.Fields{
"headerIndex": headerList.Len() - 1,
"blockHeight": bc.BlockHeight(),
"took": time.Since(start),
}).Debug("done processing headers")
}
}
<-bc.headersOpDone
return err
}
// processHeader processes the given header. Note that this is only thread safe
// if executed in headers operation.
func (bc *Blockchain) processHeader(h *Header, batch storage.Batch, headerList *HeaderHashList) error {
headerList.Add(h.Hash())
buf := new(bytes.Buffer)
for int(h.Index)-headerBatchCount >= int(bc.storedHeaderCount) {
if err := headerList.Write(buf, int(bc.storedHeaderCount), headerBatchCount); err != nil {
return err
}
key := storage.AppendPrefixInt(storage.IXHeaderHashList, int(bc.storedHeaderCount))
batch.Put(key, buf.Bytes())
bc.storedHeaderCount += headerBatchCount
buf.Reset()
}
buf.Reset()
if err := h.EncodeBinary(buf); err != nil {
return err
}
key := storage.AppendPrefix(storage.DataBlock, h.Hash().BytesReverse())
batch.Put(key, buf.Bytes())
batch.Put(storage.SYSCurrentHeader.Bytes(), hashAndIndexToBytes(h.Hash(), h.Index))
return nil
}
// TODO: persistBlock needs some more love, its implemented as in the original
// project. This for the sake of development speed and understanding of what
// is happening here, quite allot as you can see :). If things are wired together
// and all tests are in place, we can make a more optimized and cleaner implementation.
func (bc *Blockchain) persistBlock(block *Block) error {
var (
batch = bc.Batch()
unspentCoins = make(UnspentCoins)
spentCoins = make(SpentCoins)
accounts = make(Accounts)
assets = make(Assets)
)
if err := storeAsBlock(batch, block, 0); err != nil {
return err
}
storeAsCurrentBlock(batch, block)
for _, tx := range block.Transactions {
if err := storeAsTransaction(batch, tx, block.Index); err != nil {
return err
}
unspentCoins[tx.Hash()] = NewUnspentCoinState(len(tx.Outputs))
// Process TX outputs.
for _, output := range tx.Outputs {
account, err := accounts.getAndUpdate(bc.Store, output.ScriptHash)
if err != nil {
return err
}
if _, ok := account.Balances[output.AssetID]; ok {
account.Balances[output.AssetID] += output.Amount
} else {
account.Balances[output.AssetID] = output.Amount
}
}
// Process TX inputs that are grouped by previous hash.
for prevHash, inputs := range tx.GroupInputsByPrevHash() {
prevTX, prevTXHeight, err := bc.GetTransaction(prevHash)
if err != nil {
return fmt.Errorf("could not find previous TX: %s", prevHash)
}
for _, input := range inputs {
unspent, err := unspentCoins.getAndUpdate(bc.Store, input.PrevHash)
if err != nil {
return err
}
unspent.states[input.PrevIndex] = CoinStateSpent
prevTXOutput := prevTX.Outputs[input.PrevIndex]
account, err := accounts.getAndUpdate(bc.Store, prevTXOutput.ScriptHash)
if err != nil {
return err
}
if prevTXOutput.AssetID.Equals(governingTokenTX().Hash()) {
spentCoin := NewSpentCoinState(input.PrevHash, prevTXHeight)
spentCoin.items[input.PrevIndex] = block.Index
spentCoins[input.PrevHash] = spentCoin
}
account.Balances[prevTXOutput.AssetID] -= prevTXOutput.Amount
}
}
// Process the underlying type of the TX.
switch t := tx.Data.(type) {
case *transaction.RegisterTX:
assets[tx.Hash()] = &AssetState{
ID: tx.Hash(),
AssetType: t.AssetType,
Name: t.Name,
Amount: t.Amount,
Precision: t.Precision,
Owner: t.Owner,
Admin: t.Admin,
}
case *transaction.IssueTX:
case *transaction.ClaimTX:
case *transaction.EnrollmentTX:
case *transaction.StateTX:
case *transaction.PublishTX:
contract := &ContractState{
Script: t.Script,
ParamList: t.ParamList,
ReturnType: t.ReturnType,
HasStorage: t.NeedStorage,
Name: t.Name,
CodeVersion: t.CodeVersion,
Author: t.Author,
Email: t.Email,
Description: t.Description,
}
fmt.Printf("%+v", contract)
case *transaction.InvocationTX:
}
}
// Persist all to storage.
if err := accounts.commit(batch); err != nil {
return err
}
if err := unspentCoins.commit(batch); err != nil {
return err
}
if err := spentCoins.commit(batch); err != nil {
return err
}
if err := assets.commit(batch); err != nil {
return err
}
if err := bc.PutBatch(batch); err != nil {
return err
}
atomic.StoreUint32(&bc.blockHeight, block.Index)
return nil
}
func (bc *Blockchain) persist(ctx context.Context) (err error) {
var (
start = time.Now()
persisted = 0
lenCache = bc.blockCache.Len()
)
if lenCache == 0 {
return nil
}
bc.headersOp <- func(headerList *HeaderHashList) {
for i := 0; i < lenCache; i++ {
if uint32(headerList.Len()) <= bc.BlockHeight() {
return
}
hash := headerList.Get(int(bc.BlockHeight() + 1))
if block, ok := bc.blockCache.GetBlock(hash); ok {
if err = bc.persistBlock(block); err != nil {
log.Warnf("failed to persist blocks: %s", err)
return
}
bc.blockCache.Delete(hash)
persisted++
}
}
}
select {
case <-ctx.Done():
return
case <-bc.headersOpDone:
//
}
if persisted > 0 {
log.WithFields(log.Fields{
"persisted": persisted,
"headerHeight": bc.HeaderHeight(),
"blockHeight": bc.BlockHeight(),
"took": time.Since(start),
}).Info("blockchain persist completed")
}
return
}
func (bc *Blockchain) headerListLen() (n int) {
bc.headersOp <- func(headerList *HeaderHashList) {
n = headerList.Len()
}
<-bc.headersOpDone
return
}
// GetTransaction returns a TX and its height by the given hash.
func (bc *Blockchain) GetTransaction(hash util.Uint256) (*transaction.Transaction, uint32, error) {
if tx, ok := bc.memPool.TryGetValue(hash); ok {
return tx, 0, nil // the height is not actually defined for memPool transaction. Not sure if zero is a good number in this case.
}
key := storage.AppendPrefix(storage.DataTransaction, hash.BytesReverse())
b, err := bc.Get(key)
if err != nil {
return nil, 0, err
}
r := bytes.NewReader(b)
var height uint32
if err := binary.Read(r, binary.LittleEndian, &height); err != nil {
return nil, 0, err
}
tx := &transaction.Transaction{}
if err := tx.DecodeBinary(r); err != nil {
return nil, 0, err
}
return tx, height, nil
}
// GetBlock returns a Block by the given hash.
func (bc *Blockchain) GetBlock(hash util.Uint256) (*Block, error) {
key := storage.AppendPrefix(storage.DataBlock, hash.BytesReverse())
b, err := bc.Get(key)
if err != nil {
return nil, err
}
block, err := NewBlockFromTrimmedBytes(b)
if err != nil {
return nil, err
}
// TODO: persist TX first before we can handle this logic.
// if len(block.Transactions) == 0 {
// return nil, fmt.Errorf("block has no TX")
// }
return block, nil
}
func (bc *Blockchain) GetHeader(hash util.Uint256) (*Header, error) {
b, err := bc.Get(storage.AppendPrefix(storage.DataBlock, hash.BytesReverse()))
if err != nil {
return nil, err
}
block, err := NewBlockFromTrimmedBytes(b)
if err != nil {
return nil, err
}
return block.Header(), nil
}
// HasTransaction return true if the blockchain contains he given
// transaction hash.
func (bc *Blockchain) HasTransaction(hash util.Uint256) bool {
if bc.memPool.ContainsKey(hash) {
return true
}
key := storage.AppendPrefix(storage.DataTransaction, hash.BytesReverse())
if _, err := bc.Get(key); err == nil {
return true
}
return false
}
// HasBlock return true if the blockchain contains the given
// block hash.
func (bc *Blockchain) HasBlock(hash util.Uint256) bool {
if header, err := bc.GetHeader(hash); err == nil {
return header.Index <= bc.BlockHeight()
}
return false
}
// CurrentBlockHash returns the highest processed block hash.
func (bc *Blockchain) CurrentBlockHash() (hash util.Uint256) {
bc.headersOp <- func(headerList *HeaderHashList) {
hash = headerList.Get(int(bc.BlockHeight()))
}
<-bc.headersOpDone
return
}
// CurrentHeaderHash returns the hash of the latest known header.
func (bc *Blockchain) CurrentHeaderHash() (hash util.Uint256) {
bc.headersOp <- func(headerList *HeaderHashList) {
hash = headerList.Last()
}
<-bc.headersOpDone
return
}
// GetHeaderHash return the hash from the headerList by its
// height/index.
func (bc *Blockchain) GetHeaderHash(i int) (hash util.Uint256) {
bc.headersOp <- func(headerList *HeaderHashList) {
hash = headerList.Get(i)
}
<-bc.headersOpDone
return
}
// BlockHeight returns the height/index of the highest block.
func (bc *Blockchain) BlockHeight() uint32 {
return atomic.LoadUint32(&bc.blockHeight)
}
// HeaderHeight returns the index/height of the highest header.
func (bc *Blockchain) HeaderHeight() uint32 {
return uint32(bc.headerListLen() - 1)
}
// GetAssetState returns asset state from its assetID
func (bc *Blockchain) GetAssetState(assetID util.Uint256) *AssetState {
var as *AssetState
bc.Store.Seek(storage.STAsset.Bytes(), func(k, v []byte) {
var a AssetState
if err := a.DecodeBinary(bytes.NewReader(v)); err == nil && a.ID == assetID {
as = &a
}
})
return as
}
// GetAccountState returns the account state from its script hash
func (bc *Blockchain) GetAccountState(scriptHash util.Uint160) *AccountState {
var as *AccountState
bc.Store.Seek(storage.STAccount.Bytes(), func(k, v []byte) {
var a AccountState
if err := a.DecodeBinary(bytes.NewReader(v)); err == nil && a.ScriptHash == scriptHash {
as = &a
}
})
return as
}
// GetConfig returns the config stored in the blockchain
func (bc *Blockchain) GetConfig() config.ProtocolConfiguration {
return bc.config
}
// References returns a map with input prevHash as key (util.Uint256)
// and transaction output as value from a transaction t.
// @TODO: unfortunately we couldn't attach this method to the Transaction struct in the
// transaction package because of a import cycle problem. Perhaps we should think to re-design
// the code base to avoid this situation.
func (bc *Blockchain) References(t *transaction.Transaction) map[util.Uint256]*transaction.Output {
references := make(map[util.Uint256]*transaction.Output, 0)
for prevHash, inputs := range t.GroupInputsByPrevHash() {
if tx, _, err := bc.GetTransaction(prevHash); err != nil {
tx = nil
} else if tx != nil {
for _, in := range inputs {
references[in.PrevHash] = tx.Outputs[in.PrevIndex]
}
} else {
references = nil
}
}
return references
}
// FeePerByte returns network fee divided by the size of the transaction
func (bc *Blockchain) FeePerByte(t *transaction.Transaction) util.Fixed8 {
return bc.NetworkFee(t).Div(int64(t.Size()))
}
// NetworkFee returns network fee
func (bc *Blockchain) NetworkFee(t *transaction.Transaction) util.Fixed8 {
inputAmount := util.NewFixed8(0)
for _, txOutput := range bc.References(t) {
if txOutput.AssetID == utilityTokenTX().Hash() {
inputAmount.Add(txOutput.Amount)
}
}
outputAmount := util.NewFixed8(0)
for _, txOutput := range t.Outputs {
if txOutput.AssetID == utilityTokenTX().Hash() {
outputAmount.Add(txOutput.Amount)
}
}
return inputAmount.Sub(outputAmount).Sub(bc.SystemFee(t))
}
// SystemFee returns system fee
func (bc *Blockchain) SystemFee(t *transaction.Transaction) util.Fixed8 {
return bc.GetConfig().SystemFee.TryGetValue(t.Type)
}
// IsLowPriority flags a trnsaction as low priority if the network fee is less than
// LowPriorityThreshold
func (bc *Blockchain) IsLowPriority(t *transaction.Transaction) bool {
return bc.NetworkFee(t) < util.NewFixed8FromFloat(bc.GetConfig().LowPriorityThreshold)
}
// GetMemPool returns the memory pool of the blockchain.
func (bc *Blockchain) GetMemPool() MemPool {
return bc.memPool
}
// Verify verifies whether a transaction is bonafide or not.
// Golang implementation of Verify method in C# (https://github.com/neo-project/neo/blob/master/neo/Network/P2P/Payloads/Transaction.cs#L270).
func (bc *Blockchain) Verify(t *transaction.Transaction) error {
if t.Size() > transaction.MaxTransactionSize {
return errors.Errorf("invalid transaction size = %d. It shoud be less then MaxTransactionSize = %d", t.Size(), transaction.MaxTransactionSize)
}
if ok := bc.verifyInputs(t); !ok {
return errors.New("invalid transaction's inputs")
}
if ok := bc.memPool.Verify(t); !ok {
return errors.New("invalid transaction due to conflicts with the memory pool")
}
if IsDoubleSpend(bc.Store, t) {
return errors.New("invalid transaction caused by double spending")
}
if ok := bc.verifyOutputs(t); !ok {
return errors.New("invalid transaction's outputs")
}
if ok := bc.verifyResults(t); !ok {
return errors.New("invalid transaction's results")
}
for _, a := range t.Attributes {
if a.Usage == transaction.ECDH02 || a.Usage == transaction.ECDH03 {
return errors.Errorf("invalid attribute's usage = %s ", a.Usage)
}
}
return bc.VerifyWitnesses(t)
}
func (bc *Blockchain) verifyInputs(t *transaction.Transaction) bool {
for i := 1; i < len(t.Inputs); i++ {
for j := 0; j < i; j++ {
if t.Inputs[i].PrevHash == t.Inputs[j].PrevHash && t.Inputs[i].PrevIndex == t.Inputs[j].PrevIndex {
return false
}
}
}
return true
}
func (bc *Blockchain) verifyOutputs(t *transaction.Transaction) bool {
for assetID, outputs := range t.GroupOutputByAssetID() {
assetState := bc.GetAssetState(assetID)
if assetState == nil {
return false
}
if assetState.Expiration < bc.blockHeight+1 && assetState.AssetType != transaction.GoverningToken && assetState.AssetType != transaction.UtilityToken {
return false
}
for _, out := range outputs {
if int64(out.Amount)%int64(math.Pow10(8-int(assetState.Precision))) != 0 {
return false
}
}
}
return true
}
func (bc *Blockchain) verifyResults(t *transaction.Transaction) bool {
results := bc.GetTransationResults(t)
if results == nil {
return false
}
var resultsDestroy []*transaction.Result
var resultsIssue []*transaction.Result
for _, re := range results {
if re.Amount.GreaterThan(util.Fixed8(0)) {
resultsDestroy = append(resultsDestroy, re)
}
if re.Amount.LessThan(util.Fixed8(0)) {
resultsIssue = append(resultsIssue, re)
}
}
if len(resultsDestroy) > 1 {
return false
}
if len(resultsDestroy) == 1 && resultsDestroy[0].AssetID != utilityTokenTX().Hash() {
return false
}
if bc.SystemFee(t).GreaterThan(util.Fixed8(0)) && (len(resultsDestroy) == 0 || resultsDestroy[0].Amount.LessThan(bc.SystemFee(t))) {
return false
}
switch t.Type {
case transaction.MinerType, transaction.ClaimType:
for _, r := range resultsIssue {
if r.AssetID != utilityTokenTX().Hash() {
return false
}
}
break
case transaction.IssueType:
for _, r := range resultsIssue {
if r.AssetID == utilityTokenTX().Hash() {
return false
}
}
break
default:
if len(resultsIssue) > 0 {
return false
}
break
}
return true
}
// GetTransationResults returns the transaction results aggregate by assetID.
// Golang of GetTransationResults method in C# (https://github.com/neo-project/neo/blob/master/neo/Network/P2P/Payloads/Transaction.cs#L207)
func (bc *Blockchain) GetTransationResults(t *transaction.Transaction) []*transaction.Result {
var tempResults []*transaction.Result
var results []*transaction.Result
tempGroupResult := make(map[util.Uint256]util.Fixed8)
if references := bc.References(t); references == nil {
return nil
} else {
for _, output := range references {
tempResults = append(tempResults, &transaction.Result{
AssetID: output.AssetID,
Amount: output.Amount,
})
}
for _, output := range t.Outputs {
tempResults = append(tempResults, &transaction.Result{
AssetID: output.AssetID,
Amount: -output.Amount,
})
}
for _, r := range tempResults {
if amount, ok := tempGroupResult[r.AssetID]; ok {
tempGroupResult[r.AssetID] = amount.Add(r.Amount)
} else {
tempGroupResult[r.AssetID] = r.Amount
}
}
results = []*transaction.Result{} // this assignment is necessary. (Most of the time amount == 0 and results is the empty slice.)
for assetID, amount := range tempGroupResult {
if amount != util.Fixed8(0) {
results = append(results, &transaction.Result{
AssetID: assetID,
Amount: amount,
})
}
}
return results
}
}
// GetScriptHashesForVerifying returns all the ScriptHashes of a transaction which will be use
// to verify whether the transaction is bonafide or not.
// Golang implementation of GetScriptHashesForVerifying method in C# (https://github.com/neo-project/neo/blob/master/neo/Network/P2P/Payloads/Transaction.cs#L190)
func (bc *Blockchain) GetScriptHashesForVerifying(t *transaction.Transaction) ([]util.Uint160, error) {
references := bc.References(t)
if references == nil {
return nil, errors.New("Invalid operation")
}
hashes := make(map[util.Uint160]bool)
for _, i := range t.Inputs {
h := references[i.PrevHash].ScriptHash
if _, ok := hashes[h]; !ok {
hashes[h] = true
}
}
for _, a := range t.Attributes {
if a.Usage == transaction.Script {
h, err := util.Uint160DecodeBytes(a.Data)
if err != nil {
return nil, err
}
if _, ok := hashes[h]; !ok {
hashes[h] = true
}
}
}
for a, outputs := range t.GroupOutputByAssetID() {
as := bc.GetAssetState(a)
if as == nil {
return nil, errors.New("Invalid operation")
}
if as.AssetType == transaction.DutyFlag {
for _, o := range outputs {
h := o.ScriptHash
if _, ok := hashes[h]; !ok {
hashes[h] = true
}
}
}
}
// convert hashes to []util.Uint160
hashesResult := make([]util.Uint160, 0, len(hashes))
for h := range hashes {
hashesResult = append(hashesResult, h)
}
return hashesResult, nil
}
// VerifyWitnesses verify the scripts (witnesses) that come with a transactions.
// Golang implementation of VerifyWitnesses method in C# (https://github.com/neo-project/neo/blob/master/neo/SmartContract/Helper.cs#L87).
// Unfortunately the IVerifiable interface could not be implemented because we can't move the References method in blockchain.go to the transaction.go file
func (bc *Blockchain) VerifyWitnesses(t *transaction.Transaction) error {
hashes, err := bc.GetScriptHashesForVerifying(t)
if err != nil {
return err
}
witnesses := t.Scripts
if len(hashes) != len(witnesses) {
return errors.Errorf("expected len(hashes) == len(witnesses). got: %d != %d", len(hashes), len(witnesses))
}
for i := 0; i < len(hashes); i++ {
verification := witnesses[i].VerificationScript
if len(verification) == 0 {
/*TODO: replicate following C# code:
using (ScriptBuilder sb = new ScriptBuilder())
{
sb.EmitAppCall(hashes[i].ToArray());
verification = sb.ToArray();
}
*/
} else {
if h, err := witnesses[i].ScriptHash(); err != nil || hashes[i] != h {
return err
}
}
/*TODO: replicate following C# code:
using (ApplicationEngine engine = new ApplicationEngine(TriggerType.Verification, verifiable, snapshot, Fixed8.Zero))
{
engine.LoadScript(verification);
engine.LoadScript(verifiable.Witnesses[i].InvocationScript);
if (!engine.Execute()) return false;
if (engine.ResultStack.Count != 1 || !engine.ResultStack.Pop().GetBoolean()) return false;
}*/
}
return nil
}
func hashAndIndexToBytes(h util.Uint256, index uint32) []byte {
buf := make([]byte, 4)
binary.LittleEndian.PutUint32(buf, index)
return append(h.BytesReverse(), buf...)
}
func (bc *Blockchain) secondsPerBlock() int {
return bc.config.SecondsPerBlock
}