mirror of
https://github.com/FlipsideCrypto/dcrd.git
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6a0a77fd81
This converts the ExtractCoinbaseNullData function to make use of the new tokenizer instead of the far less efficient parseScript thereby significantly optimizing the function. The following is a before and after comparison of analyzing a typical coinbase script: benchmark old ns/op new ns/op delta ------------------------------------------------------------------- BenchmarkExactCoinbaseNullData 227 31.0 -86.34% benchmark old allocs new allocs delta ------------------------------------------------------------------- BenchmarkExactCoinbaseNullData 1 0 -100.00% benchmark old bytes new bytes delta ------------------------------------------------------------------- BenchmarkExactCoinbaseNullData 448 0 -100.00%
64 lines
2.4 KiB
Go
64 lines
2.4 KiB
Go
// Copyright (c) 2015-2016 The btcsuite developers
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// Copyright (c) 2015-2019 The Decred developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package txscript
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import (
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"fmt"
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)
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const (
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// LockTimeThreshold is the number below which a lock time is
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// interpreted to be a block number. Since an average of one block
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// is generated per 10 minutes, this allows blocks for about 9,512
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// years.
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LockTimeThreshold = 5e8 // Tue Nov 5 00:53:20 1985 UTC
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// maxUniqueCoinbaseNullDataSize is the maximum number of bytes allowed
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// in the pushed data output of the coinbase output that is used to
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// ensure the coinbase has a unique hash.
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maxUniqueCoinbaseNullDataSize = 256
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)
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// ExtractCoinbaseNullData ensures the passed script is a nulldata script as
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// required by the consensus rules for the coinbase output that is used to
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// ensure the coinbase has a unique hash and returns the data it pushes.
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//
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// NOTE: This function is only valid for version 0 scripts. Since the function
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// does not accept a script version, the results are undefined for other script
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// versions.
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func ExtractCoinbaseNullData(pkScript []byte) ([]byte, error) {
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// The nulldata in the coinbase must be a single OP_RETURN followed by a
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// data push up to maxUniqueCoinbaseNullDataSize bytes.
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//
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// NOTE: This is intentionally not using GetScriptClass and the related
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// functions because those are specifically for standardness checks which
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// can change over time and this function is specifically intended to be
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// used by the consensus rules.
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//
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// Also of note is that technically normal nulldata scripts support encoding
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// numbers via small opcodes, however the consensus rules require the block
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// height to be encoded as a 4-byte little-endian uint32 pushed via a normal
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// data push, as opposed to using the normal number handling semantics of
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// scripts, so this is specialized to accommodate that.
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const scriptVersion = 0
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if len(pkScript) == 1 && pkScript[0] == OP_RETURN {
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return nil, nil
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}
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if len(pkScript) > 1 && pkScript[0] == OP_RETURN {
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tokenizer := MakeScriptTokenizer(scriptVersion, pkScript[1:])
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if tokenizer.Next() && tokenizer.Done() &&
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tokenizer.Opcode() <= OP_PUSHDATA4 &&
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len(tokenizer.Data()) <= maxUniqueCoinbaseNullDataSize {
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return tokenizer.Data(), nil
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}
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}
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str := fmt.Sprintf("script %x is not well-formed coinbase nulldata",
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pkScript)
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return nil, scriptError(ErrMalformedCoinbaseNullData, str)
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}
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