// BlockRootOK checks for block self-consistency.
// If the block has no wintess txs, and no coinbase witness commitment,
// it only checks the tx merkle root. If either a witness commitment or
// any witnesses are detected, it also checks that as well.
// Returns false if anything goes wrong, true if everything is fine.
func BlockOK(blk wire.MsgBlock) bool {
var txids, wtxids []*wire.ShaHash // txids and wtxids
// witMode true if any tx has a wintess OR coinbase has wit commit
var witMode bool
for _, tx := range blk.Transactions { // make slice of (w)/txids
txid := tx.TxSha()
wtxid := tx.WitnessHash()
if !witMode && !txid.IsEqual(&wtxid) {
witMode = true
}
txids = append(txids, &txid)
wtxids = append(wtxids, &wtxid)
}
var commitBytes []byte
// try to extract coinbase witness commitment (even if !witMode)
cb := blk.Transactions[0] // get coinbase tx
for i := len(cb.TxOut) - 1; i >= 0; i-- { // start at the last txout
if bytes.HasPrefix(cb.TxOut[i].PkScript, WitMagicBytes) &&
len(cb.TxOut[i].PkScript) > 37 {
// 38 bytes or more, and starts with WitMagicBytes is a hit
commitBytes = cb.TxOut[i].PkScript[6:38]
witMode = true // it there is a wit commit it must be valid
}
}
if witMode { // witmode, so check witness tree
// first find ways witMode can be disqualified
if len(commitBytes) != 32 {
// witness in block but didn't find a wintess commitment; fail
log.Printf("block %s has witness but no witcommit",
blk.BlockSha().String())
return false
}
if len(cb.TxIn) != 1 {
log.Printf("block %s coinbase tx has %d txins (must be 1)",
blk.BlockSha().String(), len(cb.TxIn))
return false
}
if len(cb.TxIn[0].Witness) != 1 {
log.Printf("block %s coinbase has %d witnesses (must be 1)",
blk.BlockSha().String(), len(cb.TxIn[0].Witness))
return false
}
if len(cb.TxIn[0].Witness[0]) != 32 {
log.Printf("block %s coinbase has %d byte witness nonce (not 32)",
blk.BlockSha().String(), len(cb.TxIn[0].Witness[0]))
return false
}
// witness nonce is the cb's witness, subject to above constraints
witNonce, err := wire.NewShaHash(cb.TxIn[0].Witness[0])
if err != nil {
log.Printf("Witness nonce error: %s", err.Error())
return false // not sure why that'd happen but fail
}
var empty [32]byte
wtxids[0].SetBytes(empty[:]) // coinbase wtxid is 0x00...00
// witness root calculated from wtixds
witRoot := calcRoot(wtxids)
calcWitCommit := wire.DoubleSha256SH(
append(witRoot.Bytes(), witNonce.Bytes()...))
// witness root given in coinbase op_return
givenWitCommit, err := wire.NewShaHash(commitBytes)
if err != nil {
log.Printf("Witness root error: %s", err.Error())
return false // not sure why that'd happen but fail
}
// they should be the same. If not, fail.
if !calcWitCommit.IsEqual(givenWitCommit) {
log.Printf("Block %s witRoot error: calc %s given %s",
blk.BlockSha().String(),
calcWitCommit.String(), givenWitCommit.String())
return false
}
}
// got through witMode check so that should be OK;
// check regular txid merkleroot. Which is, like, trivial.
return blk.Header.MerkleRoot.IsEqual(calcRoot(txids))
}
// IngestBlock is like IngestMerkleBlock but aralphic
// different enough that it's better to have 2 separate functions
func (s *SPVCon) IngestBlock(m *wire.MsgBlock) {
var err error
// var buf bytes.Buffer
// m.SerializeWitness(&buf)
// fmt.Printf("block hex %x\n", buf.Bytes())
// for _, tx := range m.Transactions {
// fmt.Printf("wtxid: %s\n", tx.WTxSha())
// fmt.Printf(" txid: %s\n", tx.TxSha())
// fmt.Printf("%d %s", i, TxToString(tx))
// }
ok := BlockOK(*m) // check block self-consistency
if !ok {
fmt.Printf("block %s not OK!!11\n", m.BlockSha().String())
return
}
var hah HashAndHeight
select { // select here so we don't block on an unrequested mblock
case hah = <-s.blockQueue: // pop height off mblock queue
break
default:
log.Printf("Unrequested full block")
return
}
newBlockSha := m.Header.BlockSha()
if !hah.blockhash.IsEqual(&newBlockSha) {
log.Printf("full block out of order error")
return
}
fPositive := 0 // local filter false positives
reFilter := 10 // after that many false positives, regenerate filter.
// 10? Making it up. False positives have disk i/o cost, and regenning
// the filter also has costs. With a large local filter, false positives
// should be rare.
// iterate through all txs in the block, looking for matches.
// use a local bloom filter to ignore txs that don't affect us
for _, tx := range m.Transactions {
utilTx := btcutil.NewTx(tx)
if s.TS.localFilter.MatchTxAndUpdate(utilTx) {
hits, err := s.TS.Ingest(tx, hah.height)
if err != nil {
log.Printf("Incoming Tx error: %s\n", err.Error())
return
}
if hits > 0 {
// log.Printf("block %d tx %d %s ingested and matches %d utxo/adrs.",
// hah.height, i, tx.TxSha().String(), hits)
} else {
fPositive++ // matched filter but no hits
}
}
}
if fPositive > reFilter {
fmt.Printf("%d filter false positives in this block\n", fPositive)
err = s.TS.Refilter()
if err != nil {
log.Printf("Refilter error: %s\n", err.Error())
return
}
}
// write to db that we've sync'd to the height indicated in the
// merkle block. This isn't QUITE true since we haven't actually gotten
// the txs yet but if there are problems with the txs we should backtrack.
err = s.TS.SetDBSyncHeight(hah.height)
if err != nil {
log.Printf("full block sync error: %s\n", err.Error())
return
}
fmt.Printf("ingested full block %s height %d OK\n",
m.Header.BlockSha().String(), hah.height)
if hah.final { // check sync end
// don't set waitstate; instead, ask for headers again!
// this way the only thing that triggers waitstate is asking for headers,
// getting 0, calling AskForMerkBlocks(), and seeing you don't need any.
// that way you are pretty sure you're synced up.
err = s.AskForHeaders()
if err != nil {
log.Printf("Merkle block error: %s\n", err.Error())
return
}
}
return
}