Golang MsgTx.Copy方法代码示例

// calcSignatureHash will, given a script and hash type for the current script
// engine instance, calculate the signature hash to be used for signing and
// verification.
func calcSignatureHash(script []parsedOpcode, hashType SigHashType, tx *wire.MsgTx, idx int) []byte {
	// The SigHashSingle signature type signs only the corresponding input
	// and output (the output with the same index number as the input).
	//
	// Since transactions can have more inputs than outputs, this means it
	// is improper to use SigHashSingle on input indices that don't have a
	// corresponding output.
	//
	// A bug in the original Satoshi client implementation means specifying
	// an index that is out of range results in a signature hash of 1 (as a
	// uint256 little endian).  The original intent appeared to be to
	// indicate failure, but unfortunately, it was never checked and thus is
	// treated as the actual signature hash.  This buggy behavior is now
	// part of the consensus and a hard fork would be required to fix it.
	//
	// Due to this, care must be taken by software that creates transactions
	// which make use of SigHashSingle because it can lead to an extremely
	// dangerous situation where the invalid inputs will end up signing a
	// hash of 1.  This in turn presents an opportunity for attackers to
	// cleverly construct transactions which can steal those coins provided
	// they can reuse signatures.
	if hashType&sigHashMask == SigHashSingle && idx >= len(tx.TxOut) {
		var hash wire.ShaHash
		hash[0] = 0x01
		return hash[:]
	}

	// Remove all instances of OP_CODESEPARATOR from the script.
	script = removeOpcode(script, OP_CODESEPARATOR)

	// Make a deep copy of the transaction, zeroing out the script for all
	// inputs that are not currently being processed.
	txCopy := tx.Copy()
	for i := range txCopy.TxIn {
		if i == idx {
			// UnparseScript cannot fail here because removeOpcode
			// above only returns a valid script.
			sigScript, _ := unparseScript(script)
			txCopy.TxIn[idx].SignatureScript = sigScript
		} else {
			txCopy.TxIn[i].SignatureScript = nil
		}
	}

	switch hashType & sigHashMask {
	case SigHashNone:
		txCopy.TxOut = txCopy.TxOut[0:0] // Empty slice.
		for i := range txCopy.TxIn {
			if i != idx {
				txCopy.TxIn[i].Sequence = 0
			}
		}

	case SigHashSingle:
		// Resize output array to up to and including requested index.
		txCopy.TxOut = txCopy.TxOut[:idx+1]

		// All but current output get zeroed out.
		for i := 0; i < idx; i++ {
			txCopy.TxOut[i].Value = -1
			txCopy.TxOut[i].PkScript = nil
		}

		// Sequence on all other inputs is 0, too.
		for i := range txCopy.TxIn {
			if i != idx {
				txCopy.TxIn[i].Sequence = 0
			}
		}

	default:
		// Consensus treats undefined hashtypes like normal SigHashAll
		// for purposes of hash generation.
		fallthrough
	case SigHashOld:
		fallthrough
	case SigHashAll:
		// Nothing special here.
	}
	if hashType&SigHashAnyOneCanPay != 0 {
		txCopy.TxIn = txCopy.TxIn[idx : idx+1]
		idx = 0
	}

	// The final hash is the double sha256 of both the serialized modified
	// transaction and the hash type (encoded as a 4-byte little-endian
	// value) appended.
	var wbuf bytes.Buffer
	txCopy.Serialize(&wbuf)
	binary.Write(&wbuf, binary.LittleEndian, uint32(hashType))
	return wire.DoubleSha256(wbuf.Bytes())
}