// GetDoubleSpends takes a transaction and compares it with
// all transactions in the db. It returns a slice of all txids in the db
// which are double spent by the received tx.
func CheckDoubleSpends(
argTx *wire.MsgTx, txs []*wire.MsgTx) ([]*wire.ShaHash, error) {
var dubs []*wire.ShaHash // slice of all double-spent txs
argTxid := argTx.TxSha()
for _, compTx := range txs {
compTxid := compTx.TxSha()
// check if entire tx is dup
if argTxid.IsEqual(&compTxid) {
return nil, fmt.Errorf("tx %s is dup", argTxid.String())
}
// not dup, iterate through inputs of argTx
for _, argIn := range argTx.TxIn {
// iterate through inputs of compTx
for _, compIn := range compTx.TxIn {
if OutPointsEqual(
argIn.PreviousOutPoint, compIn.PreviousOutPoint) {
// found double spend
dubs = append(dubs, &compTxid)
break // back to argIn loop
}
}
}
}
return dubs, nil
}
// NewTxRecordFromMsgTx creates a new transaction record that may be inserted
// into the store.
func NewTxRecordFromMsgTx(msgTx *wire.MsgTx, received time.Time) (*TxRecord, error) {
buf := bytes.NewBuffer(make([]byte, 0, msgTx.SerializeSize()))
err := msgTx.Serialize(buf)
if err != nil {
str := "failed to serialize transaction"
return nil, storeError(ErrInput, str, err)
}
rec := &TxRecord{
MsgTx: *msgTx,
Received: received,
SerializedTx: buf.Bytes(),
Hash: msgTx.TxSha(),
}
return rec, nil
}
func (s *SPVCon) NewOutgoingTx(tx *wire.MsgTx) error {
txid := tx.TxSha()
// assign height of zero for txs we create
err := s.TS.AddTxid(&txid, 0)
if err != nil {
return err
}
_, err = s.TS.Ingest(tx, 0) // our own tx; don't keep track of false positives
if err != nil {
return err
}
// make an inv message instead of a tx message to be polite
iv1 := wire.NewInvVect(wire.InvTypeWitnessTx, &txid)
invMsg := wire.NewMsgInv()
err = invMsg.AddInvVect(iv1)
if err != nil {
return err
}
s.outMsgQueue <- invMsg
return nil
}
// TxToString prints out some info about a transaction. for testing / debugging
func TxToString(tx *wire.MsgTx) string {
str := fmt.Sprintf("size %d vsize %d wsize %d locktime %d txid %s\n",
tx.SerializeSize(), blockchain.GetTxVirtualSize(btcutil.NewTx(tx)),
tx.SerializeSize(), tx.LockTime, tx.TxSha().String())
for i, in := range tx.TxIn {
str += fmt.Sprintf("Input %d spends %s\n", i, in.PreviousOutPoint.String())
str += fmt.Sprintf("\tSigScript: %x\n", in.SignatureScript)
for j, wit := range in.Witness {
str += fmt.Sprintf("\twitness %d: %x\n", j, wit)
}
}
for i, out := range tx.TxOut {
if out != nil {
str += fmt.Sprintf("output %d script: %x amt: %d\n",
i, out.PkScript, out.Value)
} else {
str += fmt.Sprintf("output %d nil (WARNING)\n", i)
}
}
return str
}
// TxHandler takes in transaction messages that come in from either a request
// after an inv message or after a merkle block message.
func (s *SPVCon) TxHandler(m *wire.MsgTx) {
s.TS.OKMutex.Lock()
height, ok := s.TS.OKTxids[m.TxSha()]
s.TS.OKMutex.Unlock()
if !ok {
log.Printf("Tx %s unknown, will not ingest\n", m.TxSha().String())
return
}
// check for double spends
// allTxs, err := s.TS.GetAllTxs()
// if err != nil {
// log.Printf("Can't get txs from db: %s", err.Error())
// return
// }
// dubs, err := CheckDoubleSpends(m, allTxs)
// if err != nil {
// log.Printf("CheckDoubleSpends error: %s", err.Error())
// return
// }
// if len(dubs) > 0 {
// for i, dub := range dubs {
// fmt.Printf("dub %d known tx %s and new tx %s are exclusive!!!\n",
// i, dub.String(), m.TxSha().String())
// }
// }
utilTx := btcutil.NewTx(m)
if !s.HardMode || s.TS.localFilter.MatchTxAndUpdate(utilTx) {
hits, err := s.TS.Ingest(m, height)
if err != nil {
log.Printf("Incoming Tx error: %s\n", err.Error())
return
}
if hits == 0 && !s.HardMode {
log.Printf("tx %s had no hits, filter false positive.",
m.TxSha().String())
s.fPositives <- 1 // add one false positive to chan
return
}
log.Printf("tx %s ingested and matches %d utxo/adrs.",
m.TxSha().String(), hits)
}
}
// Ingest puts a tx into the DB atomically. This can result in a
// gain, a loss, or no result. Gain or loss in satoshis is returned.
func (ts *TxStore) Ingest(tx *wire.MsgTx, height int32) (uint32, error) {
var hits uint32
var err error
var nUtxoBytes [][]byte
// tx has been OK'd by SPV; check tx sanity
utilTx := btcutil.NewTx(tx) // convert for validation
// checks basic stuff like there are inputs and ouputs
err = blockchain.CheckTransactionSanity(utilTx)
if err != nil {
return hits, err
}
// note that you can't check signatures; this is SPV.
// 0 conf SPV means pretty much nothing. Anyone can say anything.
spentOPs := make([][]byte, len(tx.TxIn))
// before entering into db, serialize all inputs of the ingested tx
for i, txin := range tx.TxIn {
spentOPs[i], err = outPointToBytes(&txin.PreviousOutPoint)
if err != nil {
return hits, err
}
}
// go through txouts, and then go through addresses to match
// generate PKscripts for all addresses
wPKscripts := make([][]byte, len(ts.Adrs))
aPKscripts := make([][]byte, len(ts.Adrs))
for i, _ := range ts.Adrs {
// iterate through all our addresses
// convert regular address to witness address. (split adrs later)
wa, err := btcutil.NewAddressWitnessPubKeyHash(
ts.Adrs[i].PkhAdr.ScriptAddress(), ts.Param)
if err != nil {
return hits, err
}
wPKscripts[i], err = txscript.PayToAddrScript(wa)
if err != nil {
return hits, err
}
aPKscripts[i], err = txscript.PayToAddrScript(ts.Adrs[i].PkhAdr)
if err != nil {
return hits, err
}
}
cachedSha := tx.TxSha()
// iterate through all outputs of this tx, see if we gain
for i, out := range tx.TxOut {
for j, ascr := range aPKscripts {
// detect p2wpkh
witBool := false
if bytes.Equal(out.PkScript, wPKscripts[j]) {
witBool = true
}
if bytes.Equal(out.PkScript, ascr) || witBool { // new utxo found
var newu Utxo // create new utxo and copy into it
newu.AtHeight = height
newu.KeyIdx = ts.Adrs[j].KeyIdx
newu.Value = out.Value
newu.IsWit = witBool // copy witness version from pkscript
var newop wire.OutPoint
newop.Hash = cachedSha
newop.Index = uint32(i)
newu.Op = newop
b, err := newu.ToBytes()
if err != nil {
return hits, err
}
nUtxoBytes = append(nUtxoBytes, b)
hits++
break // txos can match only 1 script
}
}
}
err = ts.StateDB.Update(func(btx *bolt.Tx) error {
// get all 4 buckets
duf := btx.Bucket(BKTUtxos)
// sta := btx.Bucket(BKTState)
old := btx.Bucket(BKTStxos)
txns := btx.Bucket(BKTTxns)
if duf == nil || old == nil || txns == nil {
return fmt.Errorf("error: db not initialized")
}
// iterate through duffel bag and look for matches
// this makes us lose money, which is regrettable, but we need to know.
for _, nOP := range spentOPs {
v := duf.Get(nOP)
if v != nil {
hits++
// do all this just to figure out value we lost
x := make([]byte, len(nOP)+len(v))
copy(x, nOP)
copy(x[len(nOP):], v)
lostTxo, err := UtxoFromBytes(x)
if err != nil {
return err
}
// after marking for deletion, save stxo to old bucket
var st Stxo // generate spent txo
st.Utxo = lostTxo // assign outpoint
st.SpendHeight = height // spent at height
st.SpendTxid = cachedSha // spent by txid
stxb, err := st.ToBytes() // serialize
if err != nil {
return err
}
err = old.Put(nOP, stxb) // write nOP:v outpoint:stxo bytes
if err != nil {
return err
}
err = duf.Delete(nOP)
if err != nil {
return err
}
}
}
// done losing utxos, next gain utxos
// next add all new utxos to db, this is quick as the work is above
for _, ub := range nUtxoBytes {
err = duf.Put(ub[:36], ub[36:])
if err != nil {
return err
}
}
// if hits is nonzero it's a relevant tx and we should store it
var buf bytes.Buffer
tx.Serialize(&buf)
err = txns.Put(cachedSha.Bytes(), buf.Bytes())
if err != nil {
return err
}
return nil
})
return hits, err
}