// NotifyBlockConnected creates and marshalls a JSON message to notify
// of a new block connected to the main chain. The notification is sent
// to each connected wallet.
func (s *rpcServer) NotifyBlockConnected(block *btcutil.Block) {
s.ws.walletListeners.RLock()
for wltNtfn := range s.ws.walletListeners.m {
// Create notification with basic information filled in.
// This data is the same for every connected wallet.
hash, err := block.Sha()
if err != nil {
log.Error("Bad block; connected block notification dropped.")
return
}
ntfnResult := struct {
Hash string `json:"hash"`
Height int64 `json:"height"`
MinedTXs []string `json:"minedtxs"`
}{
Hash: hash.String(),
Height: block.Height(),
}
// Fill in additional wallet-specific notifications. If there
// is no request context for this wallet, no need to give this
// wallet any extra notifications.
if cxt := s.ws.requests.m[wltNtfn]; cxt != nil {
// Create list of all txs created by this wallet that appear in this
// block.
minedTxShas := make([]string, 0, len(cxt.minedTxRequests))
// TxShas does not return a non-nil error.
txShaList, _ := block.TxShas()
txList := s.server.db.FetchTxByShaList(txShaList)
for _, txReply := range txList {
if txReply.Err != nil {
continue
}
if _, ok := cxt.minedTxRequests[*txReply.Sha]; ok {
minedTxShas = append(minedTxShas, txReply.Sha.String())
s.ws.requests.RemoveMinedTxRequest(wltNtfn, txReply.Sha)
}
}
ntfnResult.MinedTXs = minedTxShas
}
var id interface{} = "btcd:blockconnected"
ntfn := btcjson.Reply{
Result: ntfnResult,
Id: &id,
}
m, _ := json.Marshal(ntfn)
wltNtfn <- m
}
s.ws.walletListeners.RUnlock()
}
// checkBIP0030 ensures blocks do not contain duplicate transactions which
// 'overwrite' older transactions that are not fully spent. This prevents an
// attack where a coinbase and all of its dependent transactions could be
// duplicated to effectively revert the overwritten transactions to a single
// confirmation thereby making them vulnerable to a double spend.
//
// For more details, see https://en.bitcoin.it/wiki/BIP_0030 and
// http://r6.ca/blog/20120206T005236Z.html.
func (b *BlockChain) checkBIP0030(node *blockNode, block *btcutil.Block) error {
// Attempt to fetch duplicate transactions for all of the transactions
// in this block from the point of view of the parent node.
fetchList, err := block.TxShas()
if err != nil {
return nil
}
fetchSet := make(map[btcwire.ShaHash]bool)
for _, txHash := range fetchList {
fetchSet[*txHash] = true
}
txResults, err := b.fetchTxStore(node, fetchSet)
if err != nil {
return err
}
// Examine the resulting data about the requested transactions.
for _, txD := range txResults {
switch txD.Err {
// A duplicate transaction was not found. This is the most
// common case.
case btcdb.TxShaMissing:
continue
// A duplicate transaction was found. This is only allowed if
// the duplicate transaction is fully spent.
case nil:
if !isTransactionSpent(txD) {
str := fmt.Sprintf("tried to overwrite "+
"transaction %v at block height %d "+
"that is not fully spent", txD.Hash,
txD.BlockHeight)
return RuleError(str)
}
// Some other unexpected error occurred. Return it now.
default:
return txD.Err
}
}
return nil
}