package core import ( "fmt" "github.com/CityOfZion/neo-go/pkg/core/storage" "github.com/CityOfZion/neo-go/pkg/core/transaction" "github.com/CityOfZion/neo-go/pkg/io" "github.com/CityOfZion/neo-go/pkg/util" ) // UnspentCoins is mapping between transactions and their unspent // coin state. type UnspentCoins map[util.Uint256]*UnspentCoinState // getAndUpdate retreives UnspentCoinState from temporary or persistent Store // and return it. If it's not present in both stores, returns a new // UnspentCoinState. func (u UnspentCoins) getAndUpdate(s storage.Store, hash util.Uint256) (*UnspentCoinState, error) { if unspent, ok := u[hash]; ok { return unspent, nil } unspent, err := getUnspentCoinStateFromStore(s, hash) if err != nil { if err != storage.ErrKeyNotFound { return nil, err } unspent = &UnspentCoinState{ states: []CoinState{}, } } u[hash] = unspent return unspent, nil } // getUnspentCoinStateFromStore retrieves UnspentCoinState from the given store func getUnspentCoinStateFromStore(s storage.Store, hash util.Uint256) (*UnspentCoinState, error) { unspent := &UnspentCoinState{} key := storage.AppendPrefix(storage.STCoin, hash.BytesReverse()) if b, err := s.Get(key); err == nil { r := io.NewBinReaderFromBuf(b) unspent.DecodeBinary(r) if r.Err != nil { return nil, fmt.Errorf("failed to decode (UnspentCoinState): %s", r.Err) } } else { return nil, err } return unspent, nil } // UnspentCoinState hold the state of a unspent coin. type UnspentCoinState struct { states []CoinState } // NewUnspentCoinState returns a new unspent coin state with N confirmed states. func NewUnspentCoinState(n int) *UnspentCoinState { u := &UnspentCoinState{ states: make([]CoinState, n), } for i := 0; i < n; i++ { u.states[i] = CoinStateConfirmed } return u } // commit writes all unspent coin states to the given Batch. func (u UnspentCoins) commit(b storage.Batch) error { buf := io.NewBufBinWriter() for hash, state := range u { state.EncodeBinary(buf.BinWriter) if buf.Err != nil { return buf.Err } key := storage.AppendPrefix(storage.STCoin, hash.BytesReverse()) b.Put(key, buf.Bytes()) buf.Reset() } return nil } // EncodeBinary encodes UnspentCoinState to the given BinWriter. func (s *UnspentCoinState) EncodeBinary(bw *io.BinWriter) { bw.WriteVarUint(uint64(len(s.states))) for _, state := range s.states { bw.WriteLE(byte(state)) } } // DecodeBinary decodes UnspentCoinState from the given BinReader. func (s *UnspentCoinState) DecodeBinary(br *io.BinReader) { lenStates := br.ReadVarUint() s.states = make([]CoinState, lenStates) for i := 0; i < int(lenStates); i++ { var state uint8 br.ReadLE(&state) s.states[i] = CoinState(state) } } // IsDoubleSpend verifies that the input transactions are not double spent. func IsDoubleSpend(s storage.Store, tx *transaction.Transaction) bool { if len(tx.Inputs) == 0 { return false } for prevHash, inputs := range tx.GroupInputsByPrevHash() { unspent := &UnspentCoinState{} key := storage.AppendPrefix(storage.STCoin, prevHash.BytesReverse()) if b, err := s.Get(key); err == nil { r := io.NewBinReaderFromBuf(b) unspent.DecodeBinary(r) if r.Err != nil { return false } if unspent == nil { return true } for _, input := range inputs { if int(input.PrevIndex) >= len(unspent.states) || unspent.states[input.PrevIndex] == CoinStateSpent { return true } } } } return false }