// maybeAddOrphan potentially adds an orphan to the orphan pool.
func (mp *txMemPool) maybeAddOrphan(tx *btcwire.MsgTx, txHash *btcwire.ShaHash) error {
// Ignore orphan transactions that are too large. This helps avoid
// a memory exhaustion attack based on sending a lot of really large
// orphans. In the case there is a valid transaction larger than this,
// it will ultimtely be rebroadcast after the parent transactions
// have been mined or otherwise received.
//
// Note that the number of orphan transactions in the orphan pool is
// also limited, so this equates to a maximum memory used of
// maxOrphanTxSize * maxOrphanTransactions (which is 500MB as of the
// time this comment was written).
var serializedTxBuf bytes.Buffer
err := tx.Serialize(&serializedTxBuf)
if err != nil {
return err
}
serializedLen := serializedTxBuf.Len()
if serializedLen > maxOrphanTxSize {
str := fmt.Sprintf("orphan transaction size of %d bytes is "+
"larger than max allowed size of %d bytes",
serializedLen, maxOrphanTxSize)
return TxRuleError(str)
}
// Add the orphan if the none of the above disqualified it.
mp.addOrphan(tx, txHash)
return nil
}
// SignRawTransaction2Async returns an instance of a type that can be used to
// get the result of the RPC at some future time by invoking the Receive
// function on the returned instance.
//
// See SignRawTransaction2 for the blocking version and more details.
func (c *Client) SignRawTransaction2Async(tx *btcwire.MsgTx, inputs []btcjson.RawTxInput) FutureSignRawTransactionResult {
txHex := ""
if tx != nil {
// Serialize the transaction and convert to hex string.
buf := bytes.NewBuffer(make([]byte, 0, tx.SerializeSize()))
if err := tx.Serialize(buf); err != nil {
return newFutureError(err)
}
txHex = hex.EncodeToString(buf.Bytes())
}
id := c.NextID()
cmd, err := btcjson.NewSignRawTransactionCmd(id, txHex, inputs)
if err != nil {
return newFutureError(err)
}
return c.sendCmd(cmd)
}
// checkTransactionStandard performs a series of checks on a transaction to
// ensure it is a "standard" transaction. A standard transaction is one that
// conforms to several additional limiting cases over what is considered a
// "sane" transaction such as having a version in the supported range, being
// finalized, conforming to more stringent size constraints, having scripts
// of recognized forms, and not containing "dust" outputs (those that are
// so small it costs more to process them than they are worth).
func checkTransactionStandard(tx *btcwire.MsgTx, height int64) error {
// The transaction must be a currently supported version.
if tx.Version > btcwire.TxVersion || tx.Version < 1 {
str := fmt.Sprintf("transaction version %d is not in the "+
"valid range of %d-%d", tx.Version, 1,
btcwire.TxVersion)
return TxRuleError(str)
}
// The transaction must be finalized to be standard and therefore
// considered for inclusion in a block.
if !btcchain.IsFinalizedTransaction(tx, height, time.Now()) {
str := fmt.Sprintf("transaction is not finalized")
return TxRuleError(str)
}
// Since extremely large transactions with a lot of inputs can cost
// almost as much to process as the sender fees, limit the maximum
// size of a transaction. This also helps mitigate CPU exhaustion
// attacks.
var serializedTxBuf bytes.Buffer
err := tx.Serialize(&serializedTxBuf)
if err != nil {
return err
}
serializedLen := serializedTxBuf.Len()
if serializedLen > maxStandardTxSize {
str := fmt.Sprintf("transaction size of %v is larger than max "+
"allowed size of %v", serializedLen, maxStandardTxSize)
return TxRuleError(str)
}
for i, txIn := range tx.TxIn {
// Each transaction input signature script must not exceed the
// maximum size allowed for a standard transaction. See
// the comment on maxStandardSigScriptSize for more details.
sigScriptLen := len(txIn.SignatureScript)
if sigScriptLen > maxStandardSigScriptSize {
str := fmt.Sprintf("transaction input %d: signature "+
"script size of %d bytes is large than max "+
"allowed size of %d bytes", i, sigScriptLen,
maxStandardSigScriptSize)
return TxRuleError(str)
}
// Each transaction input signature script must only contain
// opcodes which push data onto the stack.
if !btcscript.IsPushOnlyScript(txIn.SignatureScript) {
str := fmt.Sprintf("transaction input %d: signature "+
"script is not push only", i)
return TxRuleError(str)
}
}
// None of the output public key scripts can be a non-standard script or
// be "dust".
for i, txOut := range tx.TxOut {
err := checkPkScriptStandard(txOut.PkScript)
if err != nil {
str := fmt.Sprintf("transaction output %d: %v", i, err)
return TxRuleError(str)
}
if isDust(txOut) {
str := fmt.Sprintf("transaction output %d: payment "+
"of %d is dust", i, txOut.Value)
return TxRuleError(str)
}
}
return nil
}
// toHex converts a msgTx into a hex string.
func ToHex(tx *btcwire.MsgTx) string {
buf := bytes.NewBuffer(make([]byte, 0, tx.SerializeSize()))
tx.Serialize(buf)
txHex := hex.EncodeToString(buf.Bytes())
return txHex
}