core: track NEP5 transfers

pkg/core/blockchain.go

@@ -754,18 +754,26 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 	return nil
 }
 
-func parseUint160(addr []byte) *util.Uint160 {
+func parseUint160(addr []byte) util.Uint160 {
 	if u, err := util.Uint160DecodeBytesBE(addr); err == nil {
-		return &u
+		return u
 	}
-	return nil
+	return util.Uint160{}
 }
 
 func (bc *Blockchain) processNEP5Transfer(cache *cachedDao, tx *transaction.Transaction, b *block.Block, sc util.Uint160, from, to []byte, amount int64) {
 	toAddr := parseUint160(to)
 	fromAddr := parseUint160(from)
-	if fromAddr != nil {
-		acc, err := cache.GetAccountStateOrNew(*fromAddr)
+	transfer := &state.NEP5Transfer{
+		Asset:     sc,
+		From:      fromAddr,
+		To:        toAddr,
+		Block:     b.Index,
+		Timestamp: b.Timestamp,
+		Tx:        tx.Hash(),
+	}
+	if !fromAddr.Equals(util.Uint160{}) {
+		acc, err := cache.GetAccountStateOrNew(fromAddr)
 		if err != nil {
 			return
 		}
@@ -779,9 +787,14 @@ func (bc *Blockchain) processNEP5Transfer(cache *cachedDao, tx *transaction.Tran
 		if err := cache.PutAccountState(acc); err != nil {
 			return
 		}
+
+		transfer.Amount = -amount
+		if err := cache.AppendNEP5Transfer(fromAddr, transfer); err != nil {
+			return
+		}
 	}
-	if toAddr != nil {
-		acc, err := cache.GetAccountStateOrNew(*toAddr)
+	if !toAddr.Equals(util.Uint160{}) {
+		acc, err := cache.GetAccountStateOrNew(toAddr)
 		if err != nil {
 			return
 		}
@@ -795,6 +808,11 @@ func (bc *Blockchain) processNEP5Transfer(cache *cachedDao, tx *transaction.Tran
 		if err := cache.PutAccountState(acc); err != nil {
 			return
 		}
+
+		transfer.Amount = amount
+		if err := cache.AppendNEP5Transfer(fromAddr, transfer); err != nil {
+			return
+		}
 	}
 }
 

pkg/core/dao.go

@@ -135,6 +135,41 @@ func (dao *dao) DeleteContractState(hash util.Uint160) error {
 
 // -- end contracts.
 
+// -- start transfer log.
+
+// GetNEP5TransferLog retrieves transfer log from the cache.
+func (dao *dao) GetNEP5TransferLog(acc util.Uint160) (*state.NEP5TransferLog, error) {
+	key := storage.AppendPrefix(storage.STNEP5Transfers, acc.BytesBE())
+	value, err := dao.store.Get(key)
+	if err != nil {
+		return nil, err
+	}
+	return &state.NEP5TransferLog{Raw: value}, nil
+}
+
+// PutNEP5TransferLog saves given transfer log in the cache.
+func (dao *dao) PutNEP5TransferLog(acc util.Uint160, lg *state.NEP5TransferLog) error {
+	key := storage.AppendPrefix(storage.STNEP5Transfers, acc.BytesBE())
+	return dao.store.Put(key, lg.Raw)
+}
+
+// AppendNEP5Transfer appends a single NEP5 transfer to a log.
+func (dao *dao) AppendNEP5Transfer(acc util.Uint160, tr *state.NEP5Transfer) error {
+	lg, err := dao.GetNEP5TransferLog(acc)
+	if err != nil {
+		if err != storage.ErrKeyNotFound {
+			return err
+		}
+		lg = new(state.NEP5TransferLog)
+	}
+	if err := lg.Append(tr); err != nil {
+		return err
+	}
+	return dao.PutNEP5TransferLog(acc, lg)
+}
+
+// -- end transfer log.
+
 // -- start unspent coins.
 
 // GetUnspentCoinStateOrNew gets UnspentCoinState from temporary or persistent Store

pkg/core/state/nep5.go

@@ -2,6 +2,7 @@ package state
 
 import (
 	"github.com/nspcc-dev/neo-go/pkg/io"
+	"github.com/nspcc-dev/neo-go/pkg/util"
 )
 
 // NEP5Tracker contains info about a single account in a NEP5 contract.
@@ -13,6 +14,44 @@ type NEP5Tracker struct {
 	LastUpdatedBlock uint32
 }
 
+// NEP5TransferLog is a log of NEP5 token transfers for the specific command.
+type NEP5TransferLog struct {
+	Raw []byte
+}
+
+// NEP5TransferSize is a size of a marshaled NEP5Transfer struct in bytes.
+const NEP5TransferSize = util.Uint160Size*3 + 8 + 4 + 4 + util.Uint256Size
+
+// NEP5Transfer represents a single NEP5 Transfer event.
+type NEP5Transfer struct {
+	// Asset is a NEP5 contract hash.
+	Asset util.Uint160
+	// Address is the address of the sender.
+	From util.Uint160
+	// To is the address of the receiver.
+	To util.Uint160
+	// Amount is the amount of tokens transferred.
+	// It is negative when tokens are sent and positive if they are received.
+	Amount int64
+	// Block is a number of block when the event occured.
+	Block uint32
+	// Timestamp is the timestamp of the block where transfer occured.
+	Timestamp uint32
+	// Tx is a hash the transaction.
+	Tx util.Uint256
+}
+
+// Append appends single transfer to a log.
+func (lg *NEP5TransferLog) Append(tr *NEP5Transfer) error {
+	w := io.NewBufBinWriter()
+	tr.EncodeBinary(w.BinWriter)
+	if w.Err != nil {
+		return w.Err
+	}
+	lg.Raw = append(lg.Raw, w.Bytes()...)
+	return nil
+}
+
 // EncodeBinary implements io.Serializable interface.
 func (t *NEP5Tracker) EncodeBinary(w *io.BinWriter) {
 	w.WriteU64LE(uint64(t.Balance))
@@ -24,3 +63,26 @@ func (t *NEP5Tracker) DecodeBinary(r *io.BinReader) {
 	t.Balance = int64(r.ReadU64LE())
 	t.LastUpdatedBlock = r.ReadU32LE()
 }
+
+// EncodeBinary implements io.Serializable interface.
+// Note: change NEP5TransferSize constant when changing this function.
+func (t *NEP5Transfer) EncodeBinary(w *io.BinWriter) {
+	w.WriteBytes(t.Asset[:])
+	w.WriteBytes(t.Tx[:])
+	w.WriteBytes(t.From[:])
+	w.WriteBytes(t.To[:])
+	w.WriteU32LE(t.Block)
+	w.WriteU32LE(t.Timestamp)
+	w.WriteU64LE(uint64(t.Amount))
+}
+
+// DecodeBinary implements io.Serializable interface.
+func (t *NEP5Transfer) DecodeBinary(r *io.BinReader) {
+	r.ReadBytes(t.Asset[:])
+	r.ReadBytes(t.Tx[:])
+	r.ReadBytes(t.From[:])
+	r.ReadBytes(t.To[:])
+	t.Block = r.ReadU32LE()
+	t.Timestamp = r.ReadU32LE()
+	t.Amount = int64(r.ReadU64LE())
+}

pkg/core/state/nep5_test.go

@@ -18,6 +18,20 @@ func TestNEP5Tracker_EncodeBinary(t *testing.T) {
 	testEncodeDecode(t, expected, new(NEP5Tracker))
 }
 
+func TestNEP5Transfer_DecodeBinary(t *testing.T) {
+	expected := &NEP5Transfer{
+		Asset:     util.Uint160{1, 2, 3},
+		From:      util.Uint160{5, 6, 7},
+		To:        util.Uint160{8, 9, 10},
+		Amount:    42,
+		Block:     12345,
+		Timestamp: 54321,
+		Tx:        util.Uint256{8, 5, 3},
+	}
+
+	testEncodeDecode(t, expected, new(NEP5Transfer))
+}
+
 func testEncodeDecode(t *testing.T, expected, actual io.Serializable) {
 	w := io.NewBufBinWriter()
 	expected.EncodeBinary(w.BinWriter)

pkg/core/storage/store.go

@@ -17,6 +17,7 @@ const (
 	STNotification    KeyPrefix = 0x4d
 	STContract        KeyPrefix = 0x50
 	STStorage         KeyPrefix = 0x70
+	STNEP5Transfers   KeyPrefix = 0x72
 	IXHeaderHashList  KeyPrefix = 0x80
 	IXValidatorsCount KeyPrefix = 0x90
 	SYSCurrentBlock   KeyPrefix = 0xc0