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Merge pull request #1769 from Roasbeef/txscript_zero_alloc_optimization_refactor

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txscript: backport tokenizer from dcrd
This commit is contained in:
Olaoluwa Osuntokun 2021-11-16 19:14:28 -08:00 committed by GitHub
commit 7070d53e09
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GPG key ID: 4AEE18F83AFDEB23
22 changed files with 2780 additions and 5027 deletions
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4
txscript/README.md
View file

@ -37,6 +37,10 @@ $ go get -u github.com/btcsuite/btcd/txscript
* [Manually Signing a Transaction Output](https://pkg.go.dev/github.com/btcsuite/btcd/txscript#example-SignTxOutput)
Demonstrates manually creating and signing a redeem transaction.
* [Counting Opcodes in Scripts](http://godoc.org/github.com/decred/dcrd/txscript#example-ScriptTokenizer)
Demonstrates creating a script tokenizer instance and using it to count the
number of opcodes a script contains.
## GPG Verification Key
All official release tags are signed by Conformal so users can ensure the code

537
txscript/bench_test.go Normal file
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@ -0,0 +1,537 @@
// Copyright (c) 2018-2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package txscript
import (
"bytes"
"fmt"
"io/ioutil"
"testing"
"github.com/btcsuite/btcd/chaincfg"
"github.com/btcsuite/btcd/wire"
)
var (
// manyInputsBenchTx is a transaction that contains a lot of inputs which is
// useful for benchmarking signature hash calculation.
manyInputsBenchTx wire.MsgTx
// A mock previous output script to use in the signing benchmark.
prevOutScript = hexToBytes("a914f5916158e3e2c4551c1796708db8367207ed13bb87")
)
func init() {
// tx 620f57c92cf05a7f7e7f7d28255d5f7089437bc48e34dcfebf7751d08b7fb8f5
txHex, err := ioutil.ReadFile("data/many_inputs_tx.hex")
if err != nil {
panic(fmt.Sprintf("unable to read benchmark tx file: %v", err))
}
txBytes := hexToBytes(string(txHex))
err = manyInputsBenchTx.Deserialize(bytes.NewReader(txBytes))
if err != nil {
panic(err)
}
}
// BenchmarkCalcSigHash benchmarks how long it takes to calculate the signature
// hashes for all inputs of a transaction with many inputs.
func BenchmarkCalcSigHash(b *testing.B) {
b.ReportAllocs()
for i := 0; i < b.N; i++ {
for j := 0; j < len(manyInputsBenchTx.TxIn); j++ {
_, err := CalcSignatureHash(prevOutScript, SigHashAll,
&manyInputsBenchTx, j)
if err != nil {
b.Fatalf("failed to calc signature hash: %v", err)
}
}
}
}
// BenchmarkCalcWitnessSigHash benchmarks how long it takes to calculate the
// witness signature hashes for all inputs of a transaction with many inputs.
func BenchmarkCalcWitnessSigHash(b *testing.B) {
sigHashes := NewTxSigHashes(&manyInputsBenchTx)
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
for j := 0; j < len(manyInputsBenchTx.TxIn); j++ {
_, err := CalcWitnessSigHash(
prevOutScript, sigHashes, SigHashAll,
&manyInputsBenchTx, j, 5,
)
if err != nil {
b.Fatalf("failed to calc signature hash: %v", err)
}
}
}
}
// genComplexScript returns a script comprised of half as many opcodes as the
// maximum allowed followed by as many max size data pushes fit without
// exceeding the max allowed script size.
func genComplexScript() ([]byte, error) {
var scriptLen int
builder := NewScriptBuilder()
for i := 0; i < MaxOpsPerScript/2; i++ {
builder.AddOp(OP_TRUE)
scriptLen++
}
maxData := bytes.Repeat([]byte{0x02}, MaxScriptElementSize)
for i := 0; i < (MaxScriptSize-scriptLen)/(MaxScriptElementSize+3); i++ {
builder.AddData(maxData)
}
return builder.Script()
}
// BenchmarkScriptParsing benchmarks how long it takes to parse a very large
// script.
func BenchmarkScriptParsing(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
const scriptVersion = 0
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
tokenizer := MakeScriptTokenizer(scriptVersion, script)
for tokenizer.Next() {
_ = tokenizer.Opcode()
_ = tokenizer.Data()
_ = tokenizer.ByteIndex()
}
if err := tokenizer.Err(); err != nil {
b.Fatalf("failed to parse script: %v", err)
}
}
}
// BenchmarkDisasmString benchmarks how long it takes to disassemble a very
// large script.
func BenchmarkDisasmString(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_, err := DisasmString(script)
if err != nil {
b.Fatalf("failed to disasm script: %v", err)
}
}
}
// BenchmarkIsPubKeyScript benchmarks how long it takes to analyze a very large
// script to determine if it is a standard pay-to-pubkey script.
func BenchmarkIsPubKeyScript(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = IsPayToPubKey(script)
}
}
// BenchmarkIsPubKeyHashScript benchmarks how long it takes to analyze a very
// large script to determine if it is a standard pay-to-pubkey-hash script.
func BenchmarkIsPubKeyHashScript(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = IsPayToPubKeyHash(script)
}
}
// BenchmarkIsPayToScriptHash benchmarks how long it takes IsPayToScriptHash to
// analyze a very large script.
func BenchmarkIsPayToScriptHash(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = IsPayToScriptHash(script)
}
}
// BenchmarkIsMultisigScriptLarge benchmarks how long it takes IsMultisigScript
// to analyze a very large script.
func BenchmarkIsMultisigScriptLarge(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
isMultisig, err := IsMultisigScript(script)
if err != nil {
b.Fatalf("unexpected err: %v", err)
}
if isMultisig {
b.Fatalf("script should NOT be reported as mutisig script")
}
}
}
// BenchmarkIsMultisigScript benchmarks how long it takes IsMultisigScript to
// analyze a 1-of-2 multisig public key script.
func BenchmarkIsMultisigScript(b *testing.B) {
multisigShortForm := "1 " +
"DATA_33 " +
"0x030478aaaa2be30772f1e69e581610f1840b3cf2fe7228ee0281cd599e5746f81e " +
"DATA_33 " +
"0x0284f4d078b236a9ff91661f8ffbe012737cd3507566f30fd97d25f2b23539f3cd " +
"2 CHECKMULTISIG"
pkScript := mustParseShortForm(multisigShortForm)
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
isMultisig, err := IsMultisigScript(pkScript)
if err != nil {
b.Fatalf("unexpected err: %v", err)
}
if !isMultisig {
b.Fatalf("script should be reported as a mutisig script")
}
}
}
// BenchmarkIsMultisigSigScript benchmarks how long it takes IsMultisigSigScript
// to analyze a very large script.
func BenchmarkIsMultisigSigScriptLarge(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
if IsMultisigSigScript(script) {
b.Fatalf("script should NOT be reported as mutisig sig script")
}
}
}
// BenchmarkIsMultisigSigScript benchmarks how long it takes IsMultisigSigScript
// to analyze both a 1-of-2 multisig public key script (which should be false)
// and a signature script comprised of a pay-to-script-hash 1-of-2 multisig
// redeem script (which should be true).
func BenchmarkIsMultisigSigScript(b *testing.B) {
multisigShortForm := "1 " +
"DATA_33 " +
"0x030478aaaa2be30772f1e69e581610f1840b3cf2fe7228ee0281cd599e5746f81e " +
"DATA_33 " +
"0x0284f4d078b236a9ff91661f8ffbe012737cd3507566f30fd97d25f2b23539f3cd " +
"2 CHECKMULTISIG"
pkScript := mustParseShortForm(multisigShortForm)
sigHex := "0x304402205795c3ab6ba11331eeac757bf1fc9c34bef0c7e1a9c8bd5eebb8" +
"82f3b79c5838022001e0ab7b4c7662e4522dc5fa479e4b4133fa88c6a53d895dc1d5" +
"2eddc7bbcf2801 "
sigScript := mustParseShortForm("DATA_71 " + sigHex + "DATA_71 " +
multisigShortForm)
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
if IsMultisigSigScript(pkScript) {
b.Fatalf("script should NOT be reported as mutisig sig script")
}
if !IsMultisigSigScript(sigScript) {
b.Fatalf("script should be reported as a mutisig sig script")
}
}
}
// BenchmarkIsPushOnlyScript benchmarks how long it takes IsPushOnlyScript to
// analyze a very large script.
func BenchmarkIsPushOnlyScript(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = IsPushOnlyScript(script)
}
}
// BenchmarkIsWitnessPubKeyHash benchmarks how long it takes to analyze a very
// large script to determine if it is a standard witness pubkey hash script.
func BenchmarkIsWitnessPubKeyHash(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = IsPayToWitnessPubKeyHash(script)
}
}
// BenchmarkIsWitnessScriptHash benchmarks how long it takes to analyze a very
// large script to determine if it is a standard witness script hash script.
func BenchmarkIsWitnessScriptHash(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = IsPayToWitnessScriptHash(script)
}
}
// BenchmarkIsNullDataScript benchmarks how long it takes to analyze a very
// large script to determine if it is a standard nulldata script.
func BenchmarkIsNullDataScript(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = IsNullData(script)
}
}
// BenchmarkIsUnspendable benchmarks how long it takes IsUnspendable to analyze
// a very large script.
func BenchmarkIsUnspendable(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = IsUnspendable(script)
}
}
// BenchmarkGetSigOpCount benchmarks how long it takes to count the signature
// operations of a very large script.
func BenchmarkGetSigOpCount(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = GetSigOpCount(script)
}
}
// BenchmarkGetPreciseSigOpCount benchmarks how long it takes to count the
// signature operations of a very large script using the more precise counting
// method.
func BenchmarkGetPreciseSigOpCount(b *testing.B) {
redeemScript, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
// Create a fake pay-to-script-hash to pass the necessary checks and create
// the signature script accordingly by pushing the generated "redeem" script
// as the final data push so the benchmark will cover the p2sh path.
scriptHash := "0x0000000000000000000000000000000000000001"
pkScript := mustParseShortForm("HASH160 DATA_20 " + scriptHash + " EQUAL")
sigScript, err := NewScriptBuilder().AddFullData(redeemScript).Script()
if err != nil {
b.Fatalf("failed to create signature script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = GetPreciseSigOpCount(sigScript, pkScript, true)
}
}
// BenchmarkGetWitnessSigOpCount benchmarks how long it takes to count the
// witness signature operations of a very large script.
func BenchmarkGetWitnessSigOpCountP2WKH(b *testing.B) {
pkScript := mustParseShortForm("OP_0 DATA_20 0x0000000000000000000000000000000000000000")
redeemScript, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
witness := wire.TxWitness{
redeemScript,
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = GetWitnessSigOpCount(nil, pkScript, witness)
}
}
// BenchmarkGetWitnessSigOpCount benchmarks how long it takes to count the
// witness signature operations of a very large script.
func BenchmarkGetWitnessSigOpCountNested(b *testing.B) {
pkScript := mustParseShortForm("HASH160 DATA_20 0x0000000000000000000000000000000000000000 OP_EQUAL")
sigScript := mustParseShortForm("DATA_22 0x001600000000000000000000000000000000000000000000")
redeemScript, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
witness := wire.TxWitness{
redeemScript,
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = GetWitnessSigOpCount(sigScript, pkScript, witness)
}
}
// BenchmarkGetScriptClass benchmarks how long it takes GetScriptClass to
// analyze a very large script.
func BenchmarkGetScriptClass(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_ = GetScriptClass(script)
}
}
// BenchmarkPushedData benchmarks how long it takes to extract the pushed data
// from a very large script.
func BenchmarkPushedData(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_, err := PushedData(script)
if err != nil {
b.Fatalf("unexpected err: %v", err)
}
}
}
// BenchmarkExtractAtomicSwapDataPushesLarge benchmarks how long it takes
// ExtractAtomicSwapDataPushes to analyze a very large script.
func BenchmarkExtractAtomicSwapDataPushesLarge(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
const scriptVersion = 0
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_, err := ExtractAtomicSwapDataPushes(scriptVersion, script)
if err != nil {
b.Fatalf("unexpected err: %v", err)
}
}
}
// BenchmarkExtractAtomicSwapDataPushesLarge benchmarks how long it takes
// ExtractAtomicSwapDataPushes to analyze a standard atomic swap script.
func BenchmarkExtractAtomicSwapDataPushes(b *testing.B) {
secret := "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08"
recipient := "0000000000000000000000000000000000000001"
refund := "0000000000000000000000000000000000000002"
script := mustParseShortForm(fmt.Sprintf("IF SIZE 32 EQUALVERIFY SHA256 "+
"DATA_32 0x%s EQUALVERIFY DUP HASH160 DATA_20 0x%s ELSE 300000 "+
"CHECKLOCKTIMEVERIFY DROP DUP HASH160 DATA_20 0x%s ENDIF "+
"EQUALVERIFY CHECKSIG", secret, recipient, refund))
const scriptVersion = 0
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_, err := ExtractAtomicSwapDataPushes(scriptVersion, script)
if err != nil {
b.Fatalf("unexpected err: %v", err)
}
}
}
// BenchmarkExtractPkScriptAddrsLarge benchmarks how long it takes to analyze
// and potentially extract addresses from a very large non-standard script.
func BenchmarkExtractPkScriptAddrsLarge(b *testing.B) {
script, err := genComplexScript()
if err != nil {
b.Fatalf("failed to create benchmark script: %v", err)
}
params := &chaincfg.MainNetParams
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_, _, _, err := ExtractPkScriptAddrs(script, params)
if err != nil {
b.Fatalf("unexpected err: %v", err)
}
}
}
// BenchmarkExtractPkScriptAddrs benchmarks how long it takes to analyze and
// potentially extract addresses from a typical script.
func BenchmarkExtractPkScriptAddrs(b *testing.B) {
script := mustParseShortForm("OP_DUP HASH160 " +
"DATA_20 0x0102030405060708090a0b0c0d0e0f1011121314 " +
"EQUAL")
params := &chaincfg.MainNetParams
b.ResetTimer()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
_, _, _, err := ExtractPkScriptAddrs(script, params)
if err != nil {
b.Fatalf("unexpected err: %v", err)
}
}
}

1
txscript/data/many_inputs_tx.hex Normal file
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File diff suppressed because one or more lines are too long

571
txscript/engine.go
View file

@ -10,6 +10,7 @@ import (
"crypto/sha256"
"fmt"
"math/big"
"strings"
"github.com/btcsuite/btcd/btcec"
"github.com/btcsuite/btcd/wire"
@ -118,21 +119,84 @@ var halfOrder = new(big.Int).Rsh(btcec.S256().N, 1)
// Engine is the virtual machine that executes scripts.
type Engine struct {
scripts [][]parsedOpcode
// The following fields are set when the engine is created and must not be
// changed afterwards. The entries of the signature cache are mutated
// during execution, however, the cache pointer itself is not changed.
//
// flags specifies the additional flags which modify the execution behavior
// of the engine.
//
// tx identifies the transaction that contains the input which in turn
// contains the signature script being executed.
//
// txIdx identifies the input index within the transaction that contains
// the signature script being executed.
//
// version specifies the version of the public key script to execute. Since
// signature scripts redeem public keys scripts, this means the same version
// also extends to signature scripts and redeem scripts in the case of
// pay-to-script-hash.
//
// bip16 specifies that the public key script is of a special form that
// indicates it is a BIP16 pay-to-script-hash and therefore the
// execution must be treated as such.
//
// sigCache caches the results of signature verifications. This is useful
// since transaction scripts are often executed more than once from various
// contexts (e.g. new block templates, when transactions are first seen
// prior to being mined, part of full block verification, etc).
flags ScriptFlags
tx wire.MsgTx
txIdx int
version uint16
bip16 bool
sigCache *SigCache
hashCache *TxSigHashes
// The following fields handle keeping track of the current execution state
// of the engine.
//
// scripts houses the raw scripts that are executed by the engine. This
// includes the signature script as well as the public key script. It also
// includes the redeem script in the case of pay-to-script-hash.
//
// scriptIdx tracks the index into the scripts array for the current program
// counter.
//
// opcodeIdx tracks the number of the opcode within the current script for
// the current program counter. Note that it differs from the actual byte
// index into the script and is really only used for disassembly purposes.
//
// lastCodeSep specifies the position within the current script of the last
// OP_CODESEPARATOR.
//
// tokenizer provides the token stream of the current script being executed
// and doubles as state tracking for the program counter within the script.
//
// savedFirstStack keeps a copy of the stack from the first script when
// performing pay-to-script-hash execution.
//
// dstack is the primary data stack the various opcodes push and pop data
// to and from during execution.
//
// astack is the alternate data stack the various opcodes push and pop data
// to and from during execution.
//
// condStack tracks the conditional execution state with support for
// multiple nested conditional execution opcodes.
//
// numOps tracks the total number of non-push operations in a script and is
// primarily used to enforce maximum limits.
scripts [][]byte
scriptIdx int
scriptOff int
opcodeIdx int
lastCodeSep int
dstack stack // data stack
astack stack // alt stack
tx wire.MsgTx
txIdx int
tokenizer ScriptTokenizer
savedFirstStack [][]byte
dstack stack
astack stack
condStack []int
numOps int
flags ScriptFlags
sigCache *SigCache
hashCache *TxSigHashes
bip16 bool // treat execution as pay-to-script-hash
savedFirstStack [][]byte // stack from first script for bip16 scripts
witnessVersion int
witnessProgram []byte
inputAmount int64
@ -154,26 +218,144 @@ func (vm *Engine) isBranchExecuting() bool {
return vm.condStack[len(vm.condStack)-1] == OpCondTrue
}
// isOpcodeDisabled returns whether or not the opcode is disabled and thus is
// always bad to see in the instruction stream (even if turned off by a
// conditional).
func isOpcodeDisabled(opcode byte) bool {
switch opcode {
case OP_CAT:
return true
case OP_SUBSTR:
return true
case OP_LEFT:
return true
case OP_RIGHT:
return true
case OP_INVERT:
return true
case OP_AND:
return true
case OP_OR:
return true
case OP_XOR:
return true
case OP_2MUL:
return true
case OP_2DIV:
return true
case OP_MUL:
return true
case OP_DIV:
return true
case OP_MOD:
return true
case OP_LSHIFT:
return true
case OP_RSHIFT:
return true
default:
return false
}
}
// isOpcodeAlwaysIllegal returns whether or not the opcode is always illegal
// when passed over by the program counter even if in a non-executed branch (it
// isn't a coincidence that they are conditionals).
func isOpcodeAlwaysIllegal(opcode byte) bool {
switch opcode {
case OP_VERIF:
return true
case OP_VERNOTIF:
return true
default:
return false
}
}
// isOpcodeConditional returns whether or not the opcode is a conditional opcode
// which changes the conditional execution stack when executed.
func isOpcodeConditional(opcode byte) bool {
switch opcode {
case OP_IF:
return true
case OP_NOTIF:
return true
case OP_ELSE:
return true
case OP_ENDIF:
return true
default:
return false
}
}
// checkMinimalDataPush returns whether or not the provided opcode is the
// smallest possible way to represent the given data. For example, the value 15
// could be pushed with OP_DATA_1 15 (among other variations); however, OP_15 is
// a single opcode that represents the same value and is only a single byte
// versus two bytes.
func checkMinimalDataPush(op *opcode, data []byte) error {
opcodeVal := op.value
dataLen := len(data)
switch {
case dataLen == 0 && opcodeVal != OP_0:
str := fmt.Sprintf("zero length data push is encoded with opcode %s "+
"instead of OP_0", op.name)
return scriptError(ErrMinimalData, str)
case dataLen == 1 && data[0] >= 1 && data[0] <= 16:
if opcodeVal != OP_1+data[0]-1 {
// Should have used OP_1 .. OP_16
str := fmt.Sprintf("data push of the value %d encoded with opcode "+
"%s instead of OP_%d", data[0], op.name, data[0])
return scriptError(ErrMinimalData, str)
}
case dataLen == 1 && data[0] == 0x81:
if opcodeVal != OP_1NEGATE {
str := fmt.Sprintf("data push of the value -1 encoded with opcode "+
"%s instead of OP_1NEGATE", op.name)
return scriptError(ErrMinimalData, str)
}
case dataLen <= 75:
if int(opcodeVal) != dataLen {
// Should have used a direct push
str := fmt.Sprintf("data push of %d bytes encoded with opcode %s "+
"instead of OP_DATA_%d", dataLen, op.name, dataLen)
return scriptError(ErrMinimalData, str)
}
case dataLen <= 255:
if opcodeVal != OP_PUSHDATA1 {
str := fmt.Sprintf("data push of %d bytes encoded with opcode %s "+
"instead of OP_PUSHDATA1", dataLen, op.name)
return scriptError(ErrMinimalData, str)
}
case dataLen <= 65535:
if opcodeVal != OP_PUSHDATA2 {
str := fmt.Sprintf("data push of %d bytes encoded with opcode %s "+
"instead of OP_PUSHDATA2", dataLen, op.name)
return scriptError(ErrMinimalData, str)
}
}
return nil
}
// executeOpcode peforms execution on the passed opcode. It takes into account
// whether or not it is hidden by conditionals, but some rules still must be
// tested in this case.
func (vm *Engine) executeOpcode(pop *parsedOpcode) error {
func (vm *Engine) executeOpcode(op *opcode, data []byte) error {
// Disabled opcodes are fail on program counter.
if pop.isDisabled() {
str := fmt.Sprintf("attempt to execute disabled opcode %s",
pop.opcode.name)
if isOpcodeDisabled(op.value) {
str := fmt.Sprintf("attempt to execute disabled opcode %s", op.name)
return scriptError(ErrDisabledOpcode, str)
}
// Always-illegal opcodes are fail on program counter.
if pop.alwaysIllegal() {
str := fmt.Sprintf("attempt to execute reserved opcode %s",
pop.opcode.name)
if isOpcodeAlwaysIllegal(op.value) {
str := fmt.Sprintf("attempt to execute reserved opcode %s", op.name)
return scriptError(ErrReservedOpcode, str)
}
// Note that this includes OP_RESERVED which counts as a push operation.
if pop.opcode.value > OP_16 {
if op.value > OP_16 {
vm.numOps++
if vm.numOps > MaxOpsPerScript {
str := fmt.Sprintf("exceeded max operation limit of %d",
@ -181,67 +363,42 @@ func (vm *Engine) executeOpcode(pop *parsedOpcode) error {
return scriptError(ErrTooManyOperations, str)
}
} else if len(pop.data) > MaxScriptElementSize {
} else if len(data) > MaxScriptElementSize {
str := fmt.Sprintf("element size %d exceeds max allowed size %d",
len(pop.data), MaxScriptElementSize)
len(data), MaxScriptElementSize)
return scriptError(ErrElementTooBig, str)
}
// Nothing left to do when this is not a conditional opcode and it is
// not in an executing branch.
if !vm.isBranchExecuting() && !pop.isConditional() {
if !vm.isBranchExecuting() && !isOpcodeConditional(op.value) {
return nil
}
// Ensure all executed data push opcodes use the minimal encoding when
// the minimal data verification flag is set.
if vm.dstack.verifyMinimalData && vm.isBranchExecuting() &&
pop.opcode.value >= 0 && pop.opcode.value <= OP_PUSHDATA4 {
op.value >= 0 && op.value <= OP_PUSHDATA4 {
if err := pop.checkMinimalDataPush(); err != nil {
if err := checkMinimalDataPush(op, data); err != nil {
return err
}
}
return pop.opcode.opfunc(pop, vm)
return op.opfunc(op, data, vm)
}
// disasm is a helper function to produce the output for DisasmPC and
// DisasmScript. It produces the opcode prefixed by the program counter at the
// provided position in the script. It does no error checking and leaves that
// to the caller to provide a valid offset.
func (vm *Engine) disasm(scriptIdx int, scriptOff int) string {
return fmt.Sprintf("%02x:%04x: %s", scriptIdx, scriptOff,
vm.scripts[scriptIdx][scriptOff].print(false))
}
// validPC returns an error if the current script position is valid for
// execution, nil otherwise.
func (vm *Engine) validPC() error {
// checkValidPC returns an error if the current script position is not valid for
// execution.
func (vm *Engine) checkValidPC() error {
if vm.scriptIdx >= len(vm.scripts) {
str := fmt.Sprintf("past input scripts %v:%v %v:xxxx",
vm.scriptIdx, vm.scriptOff, len(vm.scripts))
return scriptError(ErrInvalidProgramCounter, str)
}
if vm.scriptOff >= len(vm.scripts[vm.scriptIdx]) {
str := fmt.Sprintf("past input scripts %v:%v %v:%04d",
vm.scriptIdx, vm.scriptOff, vm.scriptIdx,
len(vm.scripts[vm.scriptIdx]))
str := fmt.Sprintf("script index %d beyond total scripts %d",
vm.scriptIdx, len(vm.scripts))
return scriptError(ErrInvalidProgramCounter, str)
}
return nil
}
// curPC returns either the current script and offset, or an error if the
// position isn't valid.
func (vm *Engine) curPC() (script int, off int, err error) {
err = vm.validPC()
if err != nil {
return 0, 0, err
}
return vm.scriptIdx, vm.scriptOff, nil
}
// isWitnessVersionActive returns true if a witness program was extracted
// during the initialization of the Engine, and the program's version matches
// the specified version.
@ -269,7 +426,9 @@ func (vm *Engine) verifyWitnessProgram(witness [][]byte) error {
if err != nil {
return err
}
pops, err := parseScript(pkScript)
const scriptVersion = 0
err = checkScriptParses(vm.version, pkScript)
if err != nil {
return err
}
@ -277,7 +436,7 @@ func (vm *Engine) verifyWitnessProgram(witness [][]byte) error {
// Set the stack to the provided witness stack, then
// append the pkScript generated above as the next
// script to execute.
vm.scripts = append(vm.scripts, pops)
vm.scripts = append(vm.scripts, pkScript)
vm.SetStack(witness)
case payToWitnessScriptHashDataSize: // P2WSH
@ -307,10 +466,10 @@ func (vm *Engine) verifyWitnessProgram(witness [][]byte) error {
"witness program hash mismatch")
}
// With all the validity checks passed, parse the
// script into individual op-codes so w can execute it
// as the next script.
pops, err := parseScript(witnessScript)
// With all the validity checks passed, assert that the
// script parses without failure.
const scriptVersion = 0
err := checkScriptParses(vm.version, witnessScript)
if err != nil {
return err
}
@ -318,7 +477,7 @@ func (vm *Engine) verifyWitnessProgram(witness [][]byte) error {
// The hash matched successfully, so use the witness as
// the stack, and set the witnessScript to be the next
// script executed.
vm.scripts = append(vm.scripts, pops)
vm.scripts = append(vm.scripts, witnessScript)
vm.SetStack(witness[:len(witness)-1])
default:
@ -359,18 +518,50 @@ func (vm *Engine) verifyWitnessProgram(witness [][]byte) error {
}
// DisasmPC returns the string for the disassembly of the opcode that will be
// next to execute when Step() is called.
// next to execute when Step is called.
func (vm *Engine) DisasmPC() (string, error) {
scriptIdx, scriptOff, err := vm.curPC()
if err != nil {
if err := vm.checkValidPC(); err != nil {
return "", err
}
return vm.disasm(scriptIdx, scriptOff), nil
// Create a copy of the current tokenizer and parse the next opcode in the
// copy to avoid mutating the current one.
peekTokenizer := vm.tokenizer
if !peekTokenizer.Next() {
// Note that due to the fact that all scripts are checked for parse
// failures before this code ever runs, there should never be an error
// here, but check again to be safe in case a refactor breaks that
// assumption or new script versions are introduced with different
// semantics.
if err := peekTokenizer.Err(); err != nil {
return "", err
}
// Note that this should be impossible to hit in practice because the
// only way it could happen would be for the final opcode of a script to
// already be parsed without the script index having been updated, which
// is not the case since stepping the script always increments the
// script index when parsing and executing the final opcode of a script.
//
// However, check again to be safe in case a refactor breaks that
// assumption or new script versions are introduced with different
// semantics.
str := fmt.Sprintf("program counter beyond script index %d (bytes %x)",
vm.scriptIdx, vm.scripts[vm.scriptIdx])
return "", scriptError(ErrInvalidProgramCounter, str)
}
var buf strings.Builder
disasmOpcode(&buf, peekTokenizer.op, peekTokenizer.Data(), false)
return fmt.Sprintf("%02x:%04x: %s", vm.scriptIdx, vm.opcodeIdx,
buf.String()), nil
}
// DisasmScript returns the disassembly string for the script at the requested
// offset index. Index 0 is the signature script and 1 is the public key
// script.
// script. In the case of pay-to-script-hash, index 2 is the redeem script once
// the execution has progressed far enough to have successfully verified script
// hash and thus add the script to the scripts to execute.
func (vm *Engine) DisasmScript(idx int) (string, error) {
if idx >= len(vm.scripts) {
str := fmt.Sprintf("script index %d >= total scripts %d", idx,
@ -378,19 +569,25 @@ func (vm *Engine) DisasmScript(idx int) (string, error) {
return "", scriptError(ErrInvalidIndex, str)
}
var disstr string
for i := range vm.scripts[idx] {
disstr = disstr + vm.disasm(idx, i) + "\n"
var disbuf strings.Builder
script := vm.scripts[idx]
tokenizer := MakeScriptTokenizer(vm.version, script)
var opcodeIdx int
for tokenizer.Next() {
disbuf.WriteString(fmt.Sprintf("%02x:%04x: ", idx, opcodeIdx))
disasmOpcode(&disbuf, tokenizer.op, tokenizer.Data(), false)
disbuf.WriteByte('\n')
opcodeIdx++
}
return disstr, nil
return disbuf.String(), tokenizer.Err()
}
// CheckErrorCondition returns nil if the running script has ended and was
// successful, leaving a a true boolean on the stack. An error otherwise,
// including if the script has not finished.
func (vm *Engine) CheckErrorCondition(finalScript bool) error {
// Check execution is actually done. When pc is past the end of script
// array there are no more scripts to run.
// Check execution is actually done by ensuring the script index is after
// the final script in the array script.
if vm.scriptIdx < len(vm.scripts) {
return scriptError(ErrScriptUnfinished,
"error check when script unfinished")
@ -404,11 +601,14 @@ func (vm *Engine) CheckErrorCondition(finalScript bool) error {
"have clean stack")
}
// The final script must end with exactly one data stack item when the
// verify clean stack flag is set. Otherwise, there must be at least one
// data stack item in order to interpret it as a boolean.
if finalScript && vm.hasFlag(ScriptVerifyCleanStack) &&
vm.dstack.Depth() != 1 {
str := fmt.Sprintf("stack contains %d unexpected items",
vm.dstack.Depth()-1)
str := fmt.Sprintf("stack must contain exactly one item (contains %d)",
vm.dstack.Depth())
return scriptError(ErrCleanStack, str)
} else if vm.dstack.Depth() < 1 {
return scriptError(ErrEmptyStack,
@ -422,10 +622,14 @@ func (vm *Engine) CheckErrorCondition(finalScript bool) error {
if !v {
// Log interesting data.
log.Tracef("%v", newLogClosure(func() string {
dis0, _ := vm.DisasmScript(0)
dis1, _ := vm.DisasmScript(1)
return fmt.Sprintf("scripts failed: script0: %s\n"+
"script1: %s", dis0, dis1)
var buf strings.Builder
buf.WriteString("scripts failed:\n")
for i := range vm.scripts {
dis, _ := vm.DisasmScript(i)
buf.WriteString(fmt.Sprintf("script%d:\n", i))
buf.WriteString(dis)
}
return buf.String()
}))
return scriptError(ErrEvalFalse,
"false stack entry at end of script execution")
@ -433,25 +637,38 @@ func (vm *Engine) CheckErrorCondition(finalScript bool) error {
return nil
}
// Step will execute the next instruction and move the program counter to the
// next opcode in the script, or the next script if the current has ended. Step
// will return true in the case that the last opcode was successfully executed.
// Step executes the next instruction and moves the program counter to the next
// opcode in the script, or the next script if the current has ended. Step will
// return true in the case that the last opcode was successfully executed.
//
// The result of calling Step or any other method is undefined if an error is
// returned.
func (vm *Engine) Step() (done bool, err error) {
// Verify that it is pointing to a valid script address.
err = vm.validPC()
if err != nil {
// Verify the engine is pointing to a valid program counter.
if err := vm.checkValidPC(); err != nil {
return true, err
}
opcode := &vm.scripts[vm.scriptIdx][vm.scriptOff]
vm.scriptOff++
// Attempt to parse the next opcode from the current script.
if !vm.tokenizer.Next() {
// Note that due to the fact that all scripts are checked for parse
// failures before this code ever runs, there should never be an error
// here, but check again to be safe in case a refactor breaks that
// assumption or new script versions are introduced with different
// semantics.
if err := vm.tokenizer.Err(); err != nil {
return false, err
}
str := fmt.Sprintf("attempt to step beyond script index %d (bytes %x)",
vm.scriptIdx, vm.scripts[vm.scriptIdx])
return true, scriptError(ErrInvalidProgramCounter, str)
}
// Execute the opcode while taking into account several things such as
// disabled opcodes, illegal opcodes, maximum allowed operations per
// script, maximum script element sizes, and conditionals.
err = vm.executeOpcode(opcode)
// disabled opcodes, illegal opcodes, maximum allowed operations per script,
// maximum script element sizes, and conditionals.
err = vm.executeOpcode(vm.tokenizer.op, vm.tokenizer.Data())
if err != nil {
return true, err
}
@ -466,43 +683,53 @@ func (vm *Engine) Step() (done bool, err error) {
}
// Prepare for next instruction.
if vm.scriptOff >= len(vm.scripts[vm.scriptIdx]) {
// Illegal to have an `if' that straddles two scripts.
if err == nil && len(vm.condStack) != 0 {
vm.opcodeIdx++
if vm.tokenizer.Done() {
// Illegal to have a conditional that straddles two scripts.
if len(vm.condStack) != 0 {
return false, scriptError(ErrUnbalancedConditional,
"end of script reached in conditional execution")
}
// Alt stack doesn't persist.
// Alt stack doesn't persist between scripts.
_ = vm.astack.DropN(vm.astack.Depth())
vm.numOps = 0 // number of ops is per script.
vm.scriptOff = 0
if vm.scriptIdx == 0 && vm.bip16 {
// The number of operations is per script.
vm.numOps = 0
// Reset the opcode index for the next script.
vm.opcodeIdx = 0
// Advance to the next script as needed.
switch {
case vm.scriptIdx == 0 && vm.bip16:
vm.scriptIdx++
vm.savedFirstStack = vm.GetStack()
} else if vm.scriptIdx == 1 && vm.bip16 {
case vm.scriptIdx == 1 && vm.bip16:
// Put us past the end for CheckErrorCondition()
vm.scriptIdx++
// Check script ran successfully and pull the script
// out of the first stack and execute that.
// Check script ran successfully.
err := vm.CheckErrorCondition(false)
if err != nil {
return false, err
}
// Obtain the redeem script from the first stack and ensure it
// parses.
script := vm.savedFirstStack[len(vm.savedFirstStack)-1]
pops, err := parseScript(script)
if err != nil {
if err := checkScriptParses(vm.version, script); err != nil {
return false, err
}
vm.scripts = append(vm.scripts, pops)
vm.scripts = append(vm.scripts, script)
// Set stack to be the stack from first script minus the
// Set stack to be the stack from first script minus the redeem
// script itself
vm.SetStack(vm.savedFirstStack[:len(vm.savedFirstStack)-1])
} else if (vm.scriptIdx == 1 && vm.witnessProgram != nil) ||
(vm.scriptIdx == 2 && vm.witnessProgram != nil && vm.bip16) { // Nested P2SH.
case vm.scriptIdx == 1 && vm.witnessProgram != nil,
vm.scriptIdx == 2 && vm.witnessProgram != nil && vm.bip16: // np2sh
vm.scriptIdx++
@ -510,30 +737,46 @@ func (vm *Engine) Step() (done bool, err error) {
if err := vm.verifyWitnessProgram(witness); err != nil {
return false, err
}
} else {
default:
vm.scriptIdx++
}
// there are zero length scripts in the wild
if vm.scriptIdx < len(vm.scripts) && vm.scriptOff >= len(vm.scripts[vm.scriptIdx]) {
// Skip empty scripts.
if vm.scriptIdx < len(vm.scripts) && len(vm.scripts[vm.scriptIdx]) == 0 {
vm.scriptIdx++
}
vm.lastCodeSep = 0
if vm.scriptIdx >= len(vm.scripts) {
return true, nil
}
// Finally, update the current tokenizer used to parse through scripts
// one opcode at a time to start from the beginning of the new script
// associated with the program counter.
vm.tokenizer = MakeScriptTokenizer(vm.version, vm.scripts[vm.scriptIdx])
}
return false, nil
}
// Execute will execute all scripts in the script engine and return either nil
// for successful validation or an error if one occurred.
func (vm *Engine) Execute() (err error) {
// All script versions other than 0 currently execute without issue,
// making all outputs to them anyone can pay. In the future this
// will allow for the addition of new scripting languages.
if vm.version != 0 {
return nil
}
done := false
for !done {
log.Tracef("%v", newLogClosure(func() string {
dis, err := vm.DisasmPC()
if err != nil {
return fmt.Sprintf("stepping (%v)", err)
return fmt.Sprintf("stepping - failed to disasm pc: %v", err)
}
return fmt.Sprintf("stepping %v", dis)
}))
@ -545,7 +788,7 @@ func (vm *Engine) Execute() (err error) {
log.Tracef("%v", newLogClosure(func() string {
var dstr, astr string
// if we're tracing, dump the stacks.
// Log the non-empty stacks when tracing.
if vm.dstack.Depth() != 0 {
dstr = "Stack:\n" + vm.dstack.String()
}
@ -561,7 +804,7 @@ func (vm *Engine) Execute() (err error) {
}
// subScript returns the script since the last OP_CODESEPARATOR.
func (vm *Engine) subScript() []parsedOpcode {
func (vm *Engine) subScript() []byte {
return vm.scripts[vm.scriptIdx][vm.lastCodeSep:]
}
@ -580,6 +823,27 @@ func (vm *Engine) checkHashTypeEncoding(hashType SigHashType) error {
return nil
}
// isStrictPubKeyEncoding returns whether or not the passed public key adheres
// to the strict encoding requirements.
func isStrictPubKeyEncoding(pubKey []byte) bool {
if len(pubKey) == 33 && (pubKey[0] == 0x02 || pubKey[0] == 0x03) {
// Compressed
return true
}
if len(pubKey) == 65 {
switch pubKey[0] {
case 0x04:
// Uncompressed
return true
case 0x06, 0x07:
// Hybrid
return true
}
}
return false
}
// checkPubKeyEncoding returns whether or not the passed public key adheres to
// the strict encoding requirements if enabled.
func (vm *Engine) checkPubKeyEncoding(pubKey []byte) error {
@ -854,6 +1118,7 @@ func (vm *Engine) SetAltStack(data [][]byte) {
// engine according to the description provided by each flag.
func NewEngine(scriptPubKey []byte, tx *wire.MsgTx, txIdx int, flags ScriptFlags,
sigCache *SigCache, hashCache *TxSigHashes, inputAmount int64) (*Engine, error) {
const scriptVersion = 0
// The provided transaction input index must refer to a valid input.
if txIdx < 0 || txIdx >= len(tx.TxIn) {
@ -863,10 +1128,10 @@ func NewEngine(scriptPubKey []byte, tx *wire.MsgTx, txIdx int, flags ScriptFlags
}
scriptSig := tx.TxIn[txIdx].SignatureScript
// When both the signature script and public key script are empty the
// result is necessarily an error since the stack would end up being
// empty which is equivalent to a false top element. Thus, just return
// the relevant error now as an optimization.
// When both the signature script and public key script are empty the result
// is necessarily an error since the stack would end up being empty which is
// equivalent to a false top element. Thus, just return the relevant error
// now as an optimization.
if len(scriptSig) == 0 && len(scriptPubKey) == 0 {
return nil, scriptError(ErrEvalFalse,
"false stack entry at end of script execution")
@ -897,40 +1162,45 @@ func NewEngine(scriptPubKey []byte, tx *wire.MsgTx, txIdx int, flags ScriptFlags
"signature script is not push only")
}
// The engine stores the scripts in parsed form using a slice. This
// allows multiple scripts to be executed in sequence. For example,
// with a pay-to-script-hash transaction, there will be ultimately be
// a third script to execute.
scripts := [][]byte{scriptSig, scriptPubKey}
vm.scripts = make([][]parsedOpcode, len(scripts))
for i, scr := range scripts {
if len(scr) > MaxScriptSize {
str := fmt.Sprintf("script size %d is larger than max "+
"allowed size %d", len(scr), MaxScriptSize)
return nil, scriptError(ErrScriptTooBig, str)
}
var err error
vm.scripts[i], err = parseScript(scr)
if err != nil {
return nil, err
}
}
// Advance the program counter to the public key script if the signature
// script is empty since there is nothing to execute for it in that
// case.
if len(scripts[0]) == 0 {
vm.scriptIdx++
}
if vm.hasFlag(ScriptBip16) && isScriptHash(vm.scripts[1]) {
// The signature script must only contain data pushes for PS2H which is
// determined based on the form of the public key script.
if vm.hasFlag(ScriptBip16) && isScriptHashScript(scriptPubKey) {
// Only accept input scripts that push data for P2SH.
if !isPushOnly(vm.scripts[0]) {
// Notice that the push only checks have already been done when
// the flag to verify signature scripts are push only is set
// above, so avoid checking again.
alreadyChecked := vm.hasFlag(ScriptVerifySigPushOnly)
if !alreadyChecked && !IsPushOnlyScript(scriptSig) {
return nil, scriptError(ErrNotPushOnly,
"pay to script hash is not push only")
}
vm.bip16 = true
}
// The engine stores the scripts using a slice. This allows multiple
// scripts to be executed in sequence. For example, with a
// pay-to-script-hash transaction, there will be ultimately be a third
// script to execute.
scripts := [][]byte{scriptSig, scriptPubKey}
for _, scr := range scripts {
if len(scr) > MaxScriptSize {
str := fmt.Sprintf("script size %d is larger than max allowed "+
"size %d", len(scr), MaxScriptSize)
return nil, scriptError(ErrScriptTooBig, str)
}
const scriptVersion = 0
if err := checkScriptParses(scriptVersion, scr); err != nil {
return nil, err
}
}
vm.scripts = scripts
// Advance the program counter to the public key script if the signature
// script is empty since there is nothing to execute for it in that case.
if len(scriptSig) == 0 {
vm.scriptIdx++
}
if vm.hasFlag(ScriptVerifyMinimalData) {
vm.dstack.verifyMinimalData = true
vm.astack.verifyMinimalData = true
@ -952,7 +1222,7 @@ func NewEngine(scriptPubKey []byte, tx *wire.MsgTx, txIdx int, flags ScriptFlags
var witProgram []byte
switch {
case isWitnessProgram(vm.scripts[1]):
case IsWitnessProgram(vm.scripts[1]):
// The scriptSig must be *empty* for all native witness
// programs, otherwise we introduce malleability.
if len(scriptSig) != 0 {
@ -967,10 +1237,11 @@ func NewEngine(scriptPubKey []byte, tx *wire.MsgTx, txIdx int, flags ScriptFlags
// data push of the witness program, otherwise we
// reintroduce malleability.
sigPops := vm.scripts[0]
if len(sigPops) == 1 && canonicalPush(sigPops[0]) &&
IsWitnessProgram(sigPops[0].data) {
if len(sigPops) > 2 &&
isCanonicalPush(sigPops[0], sigPops[1:]) &&
IsWitnessProgram(sigPops[1:]) {
witProgram = sigPops[0].data
witProgram = sigPops[1:]
} else {
errStr := "signature script for witness " +
"nested p2sh is not canonical"
@ -997,6 +1268,10 @@ func NewEngine(scriptPubKey []byte, tx *wire.MsgTx, txIdx int, flags ScriptFlags
}
// Setup the current tokenizer used to parse through the script one opcode
// at a time with the script associated with the program counter.
vm.tokenizer = MakeScriptTokenizer(scriptVersion, scripts[vm.scriptIdx])
vm.tx = *tx
vm.txIdx = txIdx

19
txscript/engine_test.go
View file

@ -1,4 +1,5 @@
// Copyright (c) 2013-2017 The btcsuite developers
// Copyright (c) 2015-2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
@ -11,16 +12,16 @@ import (
"github.com/btcsuite/btcd/wire"
)
// TestBadPC sets the pc to a deliberately bad result then confirms that Step()
// TestBadPC sets the pc to a deliberately bad result then confirms that Step
// and Disasm fail correctly.
func TestBadPC(t *testing.T) {
t.Parallel()
tests := []struct {
script, off int
scriptIdx int
}{
{script: 2, off: 0},
{script: 0, off: 2},
{scriptIdx: 2},
{scriptIdx: 3},
}
// tx with almost empty scripts.
@ -59,20 +60,20 @@ func TestBadPC(t *testing.T) {
t.Errorf("Failed to create script: %v", err)
}
// set to after all scripts
vm.scriptIdx = test.script
vm.scriptOff = test.off
// Set to after all scripts.
vm.scriptIdx = test.scriptIdx
// Ensure attempting to step fails.
_, err = vm.Step()
if err == nil {
t.Errorf("Step with invalid pc (%v) succeeds!", test)
continue
}
// Ensure attempting to disassemble the current program counter fails.
_, err = vm.DisasmPC()
if err == nil {
t.Errorf("DisasmPC with invalid pc (%v) succeeds!",
test)
t.Errorf("DisasmPC with invalid pc (%v) succeeds!", test)
}
}
}

6
txscript/error.go
View file

@ -1,4 +1,5 @@
// Copyright (c) 2013-2017 The btcsuite developers
// Copyright (c) 2015-2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
@ -47,6 +48,10 @@ const (
// the provided data exceeds MaxDataCarrierSize.
ErrTooMuchNullData
// ErrUnsupportedScriptVersion is returned when an unsupported script
// version is passed to a function which deals with script analysis.
ErrUnsupportedScriptVersion
// ------------------------------------------
// Failures related to final execution state.
// ------------------------------------------
@ -352,6 +357,7 @@ var errorCodeStrings = map[ErrorCode]string{
ErrNotMultisigScript: "ErrNotMultisigScript",
ErrTooManyRequiredSigs: "ErrTooManyRequiredSigs",
ErrTooMuchNullData: "ErrTooMuchNullData",
ErrUnsupportedScriptVersion: "ErrUnsupportedScriptVersion",
ErrEarlyReturn: "ErrEarlyReturn",
ErrEmptyStack: "ErrEmptyStack",
ErrEvalFalse: "ErrEvalFalse",

2
txscript/error_test.go
View file

@ -1,4 +1,5 @@
// Copyright (c) 2017 The btcsuite developers
// Copyright (c) 2015-2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
@ -22,6 +23,7 @@ func TestErrorCodeStringer(t *testing.T) {
{ErrUnsupportedAddress, "ErrUnsupportedAddress"},
{ErrTooManyRequiredSigs, "ErrTooManyRequiredSigs"},
{ErrTooMuchNullData, "ErrTooMuchNullData"},
{ErrUnsupportedScriptVersion, "ErrUnsupportedScriptVersion"},
{ErrNotMultisigScript, "ErrNotMultisigScript"},
{ErrEarlyReturn, "ErrEarlyReturn"},
{ErrEmptyStack, "ErrEmptyStack"},

32
txscript/example_test.go
View file

@ -1,4 +1,5 @@
// Copyright (c) 2014-2016 The btcsuite developers
// Copyright (c) 2015-2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
@ -180,3 +181,34 @@ func ExampleSignTxOutput() {
// Output:
// Transaction successfully signed
}
// This example demonstrates creating a script tokenizer instance and using it
// to count the number of opcodes a script contains.
func ExampleScriptTokenizer() {
// Create a script to use in the example. Ordinarily this would come from
// some other source.
hash160 := btcutil.Hash160([]byte("example"))
script, err := txscript.NewScriptBuilder().AddOp(txscript.OP_DUP).
AddOp(txscript.OP_HASH160).AddData(hash160).
AddOp(txscript.OP_EQUALVERIFY).AddOp(txscript.OP_CHECKSIG).Script()
if err != nil {
fmt.Printf("failed to build script: %v\n", err)
return
}
// Create a tokenizer to iterate the script and count the number of opcodes.
const scriptVersion = 0
var numOpcodes int
tokenizer := txscript.MakeScriptTokenizer(scriptVersion, script)
for tokenizer.Next() {
numOpcodes++
}
if tokenizer.Err() != nil {
fmt.Printf("script failed to parse: %v\n", err)
} else {
fmt.Printf("script contains %d opcode(s)\n", numOpcodes)
}
// Output:
// script contains 5 opcode(s)
}

501
txscript/opcode.go
View file

@ -8,9 +8,10 @@ import (
"bytes"
"crypto/sha1"
"crypto/sha256"
"encoding/binary"
"encoding/hex"
"fmt"
"hash"
"strings"
"golang.org/x/crypto/ripemd160"
@ -27,7 +28,7 @@ type opcode struct {
value byte
name string
length int
opfunc func(*parsedOpcode, *Engine) error
opfunc func(*opcode, []byte, *Engine) error
}
// These constants are the values of the official opcodes used on the btc wiki,
@ -610,306 +611,52 @@ var opcodeOnelineRepls = map[string]string{
"OP_16": "16",
}
// parsedOpcode represents an opcode that has been parsed and includes any
// potential data associated with it.
type parsedOpcode struct {
opcode *opcode
data []byte
}
// isDisabled returns whether or not the opcode is disabled and thus is always
// bad to see in the instruction stream (even if turned off by a conditional).
func (pop *parsedOpcode) isDisabled() bool {
switch pop.opcode.value {
case OP_CAT:
return true
case OP_SUBSTR:
return true
case OP_LEFT:
return true
case OP_RIGHT:
return true
case OP_INVERT:
return true
case OP_AND:
return true
case OP_OR:
return true
case OP_XOR:
return true
case OP_2MUL:
return true
case OP_2DIV:
return true
case OP_MUL:
return true
case OP_DIV:
return true
case OP_MOD:
return true
case OP_LSHIFT:
return true
case OP_RSHIFT:
return true
default:
return false
}
}
// checkParseableInScript checks whether or not the current opcode is able to be
// parsed at a certain position in a script.
// This returns the position of the next opcode to be parsed in the script.
func (pop *parsedOpcode) checkParseableInScript(script []byte, scriptPos int) (int, error) {
// Parse data out of instruction.
switch {
// No additional data. Note that some of the opcodes, notably
// OP_1NEGATE, OP_0, and OP_[1-16] represent the data
// themselves.
case pop.opcode.length == 1:
scriptPos++
// Data pushes of specific lengths -- OP_DATA_[1-75].
case pop.opcode.length > 1:
if len(script[scriptPos:]) < pop.opcode.length {
str := fmt.Sprintf("opcode %s requires %d "+
"bytes, but script only has %d remaining",
pop.opcode.name, pop.opcode.length, len(script[scriptPos:]))
return 0, scriptError(ErrMalformedPush, str)
}
// Slice out the data.
pop.data = script[scriptPos+1 : scriptPos+pop.opcode.length]
scriptPos += pop.opcode.length
// Data pushes with parsed lengths -- OP_PUSHDATAP{1,2,4}.
case pop.opcode.length < 0:
var l uint
off := scriptPos + 1
if len(script[off:]) < -pop.opcode.length {
str := fmt.Sprintf("opcode %s requires %d "+
"bytes, but script only has %d remaining",
pop.opcode.name, -pop.opcode.length, len(script[off:]))
return 0, scriptError(ErrMalformedPush, str)
}
// Next -length bytes are little endian length of data.
switch pop.opcode.length {
case -1:
l = uint(script[off])
case -2:
l = ((uint(script[off+1]) << 8) |
uint(script[off]))
case -4:
l = ((uint(script[off+3]) << 24) |
(uint(script[off+2]) << 16) |
(uint(script[off+1]) << 8) |
uint(script[off]))
default:
str := fmt.Sprintf("invalid opcode length %d",
pop.opcode.length)
return 0, scriptError(ErrMalformedPush, str)
}
// Move offset to beginning of the data.
off += -pop.opcode.length
// Disallow entries that do not fit script or were
// sign extended.
if int(l) > len(script[off:]) || int(l) < 0 {
str := fmt.Sprintf("opcode %s pushes %d bytes, "+
"but script only has %d remaining",
pop.opcode.name, int(l), len(script[off:]))
return 0, scriptError(ErrMalformedPush, str)
}
pop.data = script[off : off+int(l)]
scriptPos += 1 - pop.opcode.length + int(l)
}
return scriptPos, nil
}
// alwaysIllegal returns whether or not the opcode is always illegal when passed
// over by the program counter even if in a non-executed branch (it isn't a
// coincidence that they are conditionals).
func (pop *parsedOpcode) alwaysIllegal() bool {
switch pop.opcode.value {
case OP_VERIF:
return true
case OP_VERNOTIF:
return true
default:
return false
}
}
// isConditional returns whether or not the opcode is a conditional opcode which
// changes the conditional execution stack when executed.
func (pop *parsedOpcode) isConditional() bool {
switch pop.opcode.value {
case OP_IF:
return true
case OP_NOTIF:
return true
case OP_ELSE:
return true
case OP_ENDIF:
return true
default:
return false
}
}
// checkMinimalDataPush returns whether or not the current data push uses the
// smallest possible opcode to represent it. For example, the value 15 could
// be pushed with OP_DATA_1 15 (among other variations); however, OP_15 is a
// single opcode that represents the same value and is only a single byte versus
// two bytes.
func (pop *parsedOpcode) checkMinimalDataPush() error {
data := pop.data
dataLen := len(data)
opcode := pop.opcode.value
if dataLen == 0 && opcode != OP_0 {
str := fmt.Sprintf("zero length data push is encoded with "+
"opcode %s instead of OP_0", pop.opcode.name)
return scriptError(ErrMinimalData, str)
} else if dataLen == 1 && data[0] >= 1 && data[0] <= 16 {
if opcode != OP_1+data[0]-1 {
// Should have used OP_1 .. OP_16
str := fmt.Sprintf("data push of the value %d encoded "+
"with opcode %s instead of OP_%d", data[0],
pop.opcode.name, data[0])
return scriptError(ErrMinimalData, str)
}
} else if dataLen == 1 && data[0] == 0x81 {
if opcode != OP_1NEGATE {
str := fmt.Sprintf("data push of the value -1 encoded "+
"with opcode %s instead of OP_1NEGATE",
pop.opcode.name)
return scriptError(ErrMinimalData, str)
}
} else if dataLen <= 75 {
if int(opcode) != dataLen {
// Should have used a direct push
str := fmt.Sprintf("data push of %d bytes encoded "+
"with opcode %s instead of OP_DATA_%d", dataLen,
pop.opcode.name, dataLen)
return scriptError(ErrMinimalData, str)
}
} else if dataLen <= 255 {
if opcode != OP_PUSHDATA1 {
str := fmt.Sprintf("data push of %d bytes encoded "+
"with opcode %s instead of OP_PUSHDATA1",
dataLen, pop.opcode.name)
return scriptError(ErrMinimalData, str)
}
} else if dataLen <= 65535 {
if opcode != OP_PUSHDATA2 {
str := fmt.Sprintf("data push of %d bytes encoded "+
"with opcode %s instead of OP_PUSHDATA2",
dataLen, pop.opcode.name)
return scriptError(ErrMinimalData, str)
}
}
return nil
}
// print returns a human-readable string representation of the opcode for use
// in script disassembly.
func (pop *parsedOpcode) print(oneline bool) string {
// The reference implementation one-line disassembly replaces opcodes
// which represent values (e.g. OP_0 through OP_16 and OP_1NEGATE)
// with the raw value. However, when not doing a one-line dissassembly,
// we prefer to show the actual opcode names. Thus, only replace the
// opcodes in question when the oneline flag is set.
opcodeName := pop.opcode.name
if oneline {
// disasmOpcode writes a human-readable disassembly of the provided opcode and
// data into the provided buffer. The compact flag indicates the disassembly
// should print a more compact representation of data-carrying and small integer
// opcodes. For example, OP_0 through OP_16 are replaced with the numeric value
// and data pushes are printed as only the hex representation of the data as
// opposed to including the opcode that specifies the amount of data to push as
// well.
func disasmOpcode(buf *strings.Builder, op *opcode, data []byte, compact bool) {
// Replace opcode which represent values (e.g. OP_0 through OP_16 and
// OP_1NEGATE) with the raw value when performing a compact disassembly.
opcodeName := op.name
if compact {
if replName, ok := opcodeOnelineRepls[opcodeName]; ok {
opcodeName = replName
}
// Nothing more to do for non-data push opcodes.
if pop.opcode.length == 1 {
return opcodeName
// Either write the human-readable opcode or the parsed data in hex for
// data-carrying opcodes.
switch {
case op.length == 1:
buf.WriteString(opcodeName)
default:
buf.WriteString(hex.EncodeToString(data))
}
return fmt.Sprintf("%x", pop.data)
return
}
// Nothing more to do for non-data push opcodes.
if pop.opcode.length == 1 {
return opcodeName
}
buf.WriteString(opcodeName)
switch op.length {
// Only write the opcode name for non-data push opcodes.
case 1:
return
// Add length for the OP_PUSHDATA# opcodes.
retString := opcodeName
switch pop.opcode.length {
case -1:
retString += fmt.Sprintf(" 0x%02x", len(pop.data))
buf.WriteString(fmt.Sprintf(" 0x%02x", len(data)))
case -2:
retString += fmt.Sprintf(" 0x%04x", len(pop.data))
buf.WriteString(fmt.Sprintf(" 0x%04x", len(data)))
case -4:
retString += fmt.Sprintf(" 0x%08x", len(pop.data))
buf.WriteString(fmt.Sprintf(" 0x%08x", len(data)))
}
return fmt.Sprintf("%s 0x%02x", retString, pop.data)
}
// bytes returns any data associated with the opcode encoded as it would be in
// a script. This is used for unparsing scripts from parsed opcodes.
func (pop *parsedOpcode) bytes() ([]byte, error) {
var retbytes []byte
if pop.opcode.length > 0 {
retbytes = make([]byte, 1, pop.opcode.length)
} else {
retbytes = make([]byte, 1, 1+len(pop.data)-
pop.opcode.length)
}
retbytes[0] = pop.opcode.value
if pop.opcode.length == 1 {
if len(pop.data) != 0 {
str := fmt.Sprintf("internal consistency error - "+
"parsed opcode %s has data length %d when %d "+
"was expected", pop.opcode.name, len(pop.data),
0)
return nil, scriptError(ErrInternal, str)
}
return retbytes, nil
}
nbytes := pop.opcode.length
if pop.opcode.length < 0 {
l := len(pop.data)
// tempting just to hardcode to avoid the complexity here.
switch pop.opcode.length {
case -1:
retbytes = append(retbytes, byte(l))
nbytes = int(retbytes[1]) + len(retbytes)
case -2:
retbytes = append(retbytes, byte(l&0xff),
byte(l>>8&0xff))
nbytes = int(binary.LittleEndian.Uint16(retbytes[1:])) +
len(retbytes)
case -4:
retbytes = append(retbytes, byte(l&0xff),
byte((l>>8)&0xff), byte((l>>16)&0xff),
byte((l>>24)&0xff))
nbytes = int(binary.LittleEndian.Uint32(retbytes[1:])) +
len(retbytes)
}
}
retbytes = append(retbytes, pop.data...)
if len(retbytes) != nbytes {
str := fmt.Sprintf("internal consistency error - "+
"parsed opcode %s has data length %d when %d was "+
"expected", pop.opcode.name, len(retbytes), nbytes)
return nil, scriptError(ErrInternal, str)
}
return retbytes, nil
buf.WriteString(fmt.Sprintf(" 0x%02x", data))
}
// *******************************************
@ -922,45 +669,42 @@ func (pop *parsedOpcode) bytes() ([]byte, error) {
// opcodes before executing in an initial parse step, the consensus rules
// dictate the script doesn't fail until the program counter passes over a
// disabled opcode (even when they appear in a branch that is not executed).
func opcodeDisabled(op *parsedOpcode, vm *Engine) error {
str := fmt.Sprintf("attempt to execute disabled opcode %s",
op.opcode.name)
func opcodeDisabled(op *opcode, data []byte, vm *Engine) error {
str := fmt.Sprintf("attempt to execute disabled opcode %s", op.name)
return scriptError(ErrDisabledOpcode, str)
}
// opcodeReserved is a common handler for all reserved opcodes. It returns an
// appropriate error indicating the opcode is reserved.
func opcodeReserved(op *parsedOpcode, vm *Engine) error {
str := fmt.Sprintf("attempt to execute reserved opcode %s",
op.opcode.name)
func opcodeReserved(op *opcode, data []byte, vm *Engine) error {
str := fmt.Sprintf("attempt to execute reserved opcode %s", op.name)
return scriptError(ErrReservedOpcode, str)
}
// opcodeInvalid is a common handler for all invalid opcodes. It returns an
// appropriate error indicating the opcode is invalid.
func opcodeInvalid(op *parsedOpcode, vm *Engine) error {
str := fmt.Sprintf("attempt to execute invalid opcode %s",
op.opcode.name)
func opcodeInvalid(op *opcode, data []byte, vm *Engine) error {
str := fmt.Sprintf("attempt to execute invalid opcode %s", op.name)
return scriptError(ErrReservedOpcode, str)
}
// opcodeFalse pushes an empty array to the data stack to represent false. Note
// that 0, when encoded as a number according to the numeric encoding consensus
// rules, is an empty array.
func opcodeFalse(op *parsedOpcode, vm *Engine) error {
func opcodeFalse(op *opcode, data []byte, vm *Engine) error {
vm.dstack.PushByteArray(nil)
return nil
}
// opcodePushData is a common handler for the vast majority of opcodes that push
// raw data (bytes) to the data stack.
func opcodePushData(op *parsedOpcode, vm *Engine) error {
vm.dstack.PushByteArray(op.data)
func opcodePushData(op *opcode, data []byte, vm *Engine) error {
vm.dstack.PushByteArray(data)
return nil
}
// opcode1Negate pushes -1, encoded as a number, to the data stack.
func opcode1Negate(op *parsedOpcode, vm *Engine) error {
func opcode1Negate(op *opcode, data []byte, vm *Engine) error {
vm.dstack.PushInt(scriptNum(-1))
return nil
}
@ -968,23 +712,24 @@ func opcode1Negate(op *parsedOpcode, vm *Engine) error {
// opcodeN is a common handler for the small integer data push opcodes. It
// pushes the numeric value the opcode represents (which will be from 1 to 16)
// onto the data stack.
func opcodeN(op *parsedOpcode, vm *Engine) error {
func opcodeN(op *opcode, data []byte, vm *Engine) error {
// The opcodes are all defined consecutively, so the numeric value is
// the difference.
vm.dstack.PushInt(scriptNum((op.opcode.value - (OP_1 - 1))))
vm.dstack.PushInt(scriptNum((op.value - (OP_1 - 1))))
return nil
}
// opcodeNop is a common handler for the NOP family of opcodes. As the name
// implies it generally does nothing, however, it will return an error when
// the flag to discourage use of NOPs is set for select opcodes.
func opcodeNop(op *parsedOpcode, vm *Engine) error {
switch op.opcode.value {
func opcodeNop(op *opcode, data []byte, vm *Engine) error {
switch op.value {
case OP_NOP1, OP_NOP4, OP_NOP5,
OP_NOP6, OP_NOP7, OP_NOP8, OP_NOP9, OP_NOP10:
if vm.hasFlag(ScriptDiscourageUpgradableNops) {
str := fmt.Sprintf("OP_NOP%d reserved for soft-fork "+
"upgrades", op.opcode.value-(OP_NOP1-1))
str := fmt.Sprintf("%v reserved for soft-fork "+
"upgrades", op.name)
return scriptError(ErrDiscourageUpgradableNOPs, str)
}
}
@ -1047,7 +792,7 @@ func popIfBool(vm *Engine) (bool, error) {
//
// Data stack transformation: [... bool] -> [...]
// Conditional stack transformation: [...] -> [... OpCondValue]
func opcodeIf(op *parsedOpcode, vm *Engine) error {
func opcodeIf(op *opcode, data []byte, vm *Engine) error {
condVal := OpCondFalse
if vm.isBranchExecuting() {
ok, err := popIfBool(vm)
@ -1081,7 +826,7 @@ func opcodeIf(op *parsedOpcode, vm *Engine) error {
//
// Data stack transformation: [... bool] -> [...]
// Conditional stack transformation: [...] -> [... OpCondValue]
func opcodeNotIf(op *parsedOpcode, vm *Engine) error {
func opcodeNotIf(op *opcode, data []byte, vm *Engine) error {
condVal := OpCondFalse
if vm.isBranchExecuting() {
ok, err := popIfBool(vm)
@ -1104,10 +849,10 @@ func opcodeNotIf(op *parsedOpcode, vm *Engine) error {
// An error is returned if there has not already been a matching OP_IF.
//
// Conditional stack transformation: [... OpCondValue] -> [... !OpCondValue]
func opcodeElse(op *parsedOpcode, vm *Engine) error {
func opcodeElse(op *opcode, data []byte, vm *Engine) error {
if len(vm.condStack) == 0 {
str := fmt.Sprintf("encountered opcode %s with no matching "+
"opcode to begin conditional execution", op.opcode.name)
"opcode to begin conditional execution", op.name)
return scriptError(ErrUnbalancedConditional, str)
}
@ -1130,10 +875,10 @@ func opcodeElse(op *parsedOpcode, vm *Engine) error {
// An error is returned if there has not already been a matching OP_IF.
//
// Conditional stack transformation: [... OpCondValue] -> [...]
func opcodeEndif(op *parsedOpcode, vm *Engine) error {
func opcodeEndif(op *opcode, data []byte, vm *Engine) error {
if len(vm.condStack) == 0 {
str := fmt.Sprintf("encountered opcode %s with no matching "+
"opcode to begin conditional execution", op.opcode.name)
"opcode to begin conditional execution", op.name)
return scriptError(ErrUnbalancedConditional, str)
}
@ -1146,14 +891,14 @@ func opcodeEndif(op *parsedOpcode, vm *Engine) error {
// item on the stack or when that item evaluates to false. In the latter case
// where the verification fails specifically due to the top item evaluating
// to false, the returned error will use the passed error code.
func abstractVerify(op *parsedOpcode, vm *Engine, c ErrorCode) error {
func abstractVerify(op *opcode, vm *Engine, c ErrorCode) error {
verified, err := vm.dstack.PopBool()
if err != nil {
return err
}
if !verified {
str := fmt.Sprintf("%s failed", op.opcode.name)
str := fmt.Sprintf("%s failed", op.name)
return scriptError(c, str)
}
return nil
@ -1161,13 +906,13 @@ func abstractVerify(op *parsedOpcode, vm *Engine, c ErrorCode) error {
// opcodeVerify examines the top item on the data stack as a boolean value and
// verifies it evaluates to true. An error is returned if it does not.
func opcodeVerify(op *parsedOpcode, vm *Engine) error {
func opcodeVerify(op *opcode, data []byte, vm *Engine) error {
return abstractVerify(op, vm, ErrVerify)
}
// opcodeReturn returns an appropriate error since it is always an error to
// return early from a script.
func opcodeReturn(op *parsedOpcode, vm *Engine) error {
func opcodeReturn(op *opcode, data []byte, vm *Engine) error {
return scriptError(ErrEarlyReturn, "script returned early")
}
@ -1197,7 +942,7 @@ func verifyLockTime(txLockTime, threshold, lockTime int64) error {
// validating if the transaction outputs are spendable yet. If flag
// ScriptVerifyCheckLockTimeVerify is not set, the code continues as if OP_NOP2
// were executed.
func opcodeCheckLockTimeVerify(op *parsedOpcode, vm *Engine) error {
func opcodeCheckLockTimeVerify(op *opcode, data []byte, vm *Engine) error {
// If the ScriptVerifyCheckLockTimeVerify script flag is not set, treat
// opcode as OP_NOP2 instead.
if !vm.hasFlag(ScriptVerifyCheckLockTimeVerify) {
@ -1271,7 +1016,7 @@ func opcodeCheckLockTimeVerify(op *parsedOpcode, vm *Engine) error {
// validating if the transaction outputs are spendable yet. If flag
// ScriptVerifyCheckSequenceVerify is not set, the code continues as if OP_NOP3
// were executed.
func opcodeCheckSequenceVerify(op *parsedOpcode, vm *Engine) error {
func opcodeCheckSequenceVerify(op *opcode, data []byte, vm *Engine) error {
// If the ScriptVerifyCheckSequenceVerify script flag is not set, treat
// opcode as OP_NOP3 instead.
if !vm.hasFlag(ScriptVerifyCheckSequenceVerify) {
@ -1348,7 +1093,7 @@ func opcodeCheckSequenceVerify(op *parsedOpcode, vm *Engine) error {
//
// Main data stack transformation: [... x1 x2 x3] -> [... x1 x2]
// Alt data stack transformation: [... y1 y2 y3] -> [... y1 y2 y3 x3]
func opcodeToAltStack(op *parsedOpcode, vm *Engine) error {
func opcodeToAltStack(op *opcode, data []byte, vm *Engine) error {
so, err := vm.dstack.PopByteArray()
if err != nil {
return err
@ -1363,7 +1108,7 @@ func opcodeToAltStack(op *parsedOpcode, vm *Engine) error {
//
// Main data stack transformation: [... x1 x2 x3] -> [... x1 x2 x3 y3]
// Alt data stack transformation: [... y1 y2 y3] -> [... y1 y2]
func opcodeFromAltStack(op *parsedOpcode, vm *Engine) error {
func opcodeFromAltStack(op *opcode, data []byte, vm *Engine) error {
so, err := vm.astack.PopByteArray()
if err != nil {
return err
@ -1376,35 +1121,35 @@ func opcodeFromAltStack(op *parsedOpcode, vm *Engine) error {
// opcode2Drop removes the top 2 items from the data stack.
//
// Stack transformation: [... x1 x2 x3] -> [... x1]
func opcode2Drop(op *parsedOpcode, vm *Engine) error {
func opcode2Drop(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.DropN(2)
}
// opcode2Dup duplicates the top 2 items on the data stack.
//
// Stack transformation: [... x1 x2 x3] -> [... x1 x2 x3 x2 x3]
func opcode2Dup(op *parsedOpcode, vm *Engine) error {
func opcode2Dup(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.DupN(2)
}
// opcode3Dup duplicates the top 3 items on the data stack.
//
// Stack transformation: [... x1 x2 x3] -> [... x1 x2 x3 x1 x2 x3]
func opcode3Dup(op *parsedOpcode, vm *Engine) error {
func opcode3Dup(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.DupN(3)
}
// opcode2Over duplicates the 2 items before the top 2 items on the data stack.
//
// Stack transformation: [... x1 x2 x3 x4] -> [... x1 x2 x3 x4 x1 x2]
func opcode2Over(op *parsedOpcode, vm *Engine) error {
func opcode2Over(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.OverN(2)
}
// opcode2Rot rotates the top 6 items on the data stack to the left twice.
//
// Stack transformation: [... x1 x2 x3 x4 x5 x6] -> [... x3 x4 x5 x6 x1 x2]
func opcode2Rot(op *parsedOpcode, vm *Engine) error {
func opcode2Rot(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.RotN(2)
}
@ -1412,7 +1157,7 @@ func opcode2Rot(op *parsedOpcode, vm *Engine) error {
// before them.
//
// Stack transformation: [... x1 x2 x3 x4] -> [... x3 x4 x1 x2]
func opcode2Swap(op *parsedOpcode, vm *Engine) error {
func opcode2Swap(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.SwapN(2)
}
@ -1420,7 +1165,7 @@ func opcode2Swap(op *parsedOpcode, vm *Engine) error {
//
// Stack transformation (x1==0): [... x1] -> [... x1]
// Stack transformation (x1!=0): [... x1] -> [... x1 x1]
func opcodeIfDup(op *parsedOpcode, vm *Engine) error {
func opcodeIfDup(op *opcode, data []byte, vm *Engine) error {
so, err := vm.dstack.PeekByteArray(0)
if err != nil {
return err
@ -1440,7 +1185,7 @@ func opcodeIfDup(op *parsedOpcode, vm *Engine) error {
// Stack transformation: [...] -> [... <num of items on the stack>]
// Example with 2 items: [x1 x2] -> [x1 x2 2]
// Example with 3 items: [x1 x2 x3] -> [x1 x2 x3 3]
func opcodeDepth(op *parsedOpcode, vm *Engine) error {
func opcodeDepth(op *opcode, data []byte, vm *Engine) error {
vm.dstack.PushInt(scriptNum(vm.dstack.Depth()))
return nil
}
@ -1448,28 +1193,28 @@ func opcodeDepth(op *parsedOpcode, vm *Engine) error {
// opcodeDrop removes the top item from the data stack.
//
// Stack transformation: [... x1 x2 x3] -> [... x1 x2]
func opcodeDrop(op *parsedOpcode, vm *Engine) error {
func opcodeDrop(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.DropN(1)
}
// opcodeDup duplicates the top item on the data stack.
//
// Stack transformation: [... x1 x2 x3] -> [... x1 x2 x3 x3]
func opcodeDup(op *parsedOpcode, vm *Engine) error {
func opcodeDup(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.DupN(1)
}
// opcodeNip removes the item before the top item on the data stack.
//
// Stack transformation: [... x1 x2 x3] -> [... x1 x3]
func opcodeNip(op *parsedOpcode, vm *Engine) error {
func opcodeNip(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.NipN(1)
}
// opcodeOver duplicates the item before the top item on the data stack.
//
// Stack transformation: [... x1 x2 x3] -> [... x1 x2 x3 x2]
func opcodeOver(op *parsedOpcode, vm *Engine) error {
func opcodeOver(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.OverN(1)
}
@ -1479,7 +1224,7 @@ func opcodeOver(op *parsedOpcode, vm *Engine) error {
// Stack transformation: [xn ... x2 x1 x0 n] -> [xn ... x2 x1 x0 xn]
// Example with n=1: [x2 x1 x0 1] -> [x2 x1 x0 x1]
// Example with n=2: [x2 x1 x0 2] -> [x2 x1 x0 x2]
func opcodePick(op *parsedOpcode, vm *Engine) error {
func opcodePick(op *opcode, data []byte, vm *Engine) error {
val, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1494,7 +1239,7 @@ func opcodePick(op *parsedOpcode, vm *Engine) error {
// Stack transformation: [xn ... x2 x1 x0 n] -> [... x2 x1 x0 xn]
// Example with n=1: [x2 x1 x0 1] -> [x2 x0 x1]
// Example with n=2: [x2 x1 x0 2] -> [x1 x0 x2]
func opcodeRoll(op *parsedOpcode, vm *Engine) error {
func opcodeRoll(op *opcode, data []byte, vm *Engine) error {
val, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1506,14 +1251,14 @@ func opcodeRoll(op *parsedOpcode, vm *Engine) error {
// opcodeRot rotates the top 3 items on the data stack to the left.
//
// Stack transformation: [... x1 x2 x3] -> [... x2 x3 x1]
func opcodeRot(op *parsedOpcode, vm *Engine) error {
func opcodeRot(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.RotN(1)
}
// opcodeSwap swaps the top two items on the stack.
//
// Stack transformation: [... x1 x2] -> [... x2 x1]
func opcodeSwap(op *parsedOpcode, vm *Engine) error {
func opcodeSwap(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.SwapN(1)
}
@ -1521,7 +1266,7 @@ func opcodeSwap(op *parsedOpcode, vm *Engine) error {
// second-to-top item.
//
// Stack transformation: [... x1 x2] -> [... x2 x1 x2]
func opcodeTuck(op *parsedOpcode, vm *Engine) error {
func opcodeTuck(op *opcode, data []byte, vm *Engine) error {
return vm.dstack.Tuck()
}
@ -1529,7 +1274,7 @@ func opcodeTuck(op *parsedOpcode, vm *Engine) error {
// stack.
//
// Stack transformation: [... x1] -> [... x1 len(x1)]
func opcodeSize(op *parsedOpcode, vm *Engine) error {
func opcodeSize(op *opcode, data []byte, vm *Engine) error {
so, err := vm.dstack.PeekByteArray(0)
if err != nil {
return err
@ -1543,7 +1288,7 @@ func opcodeSize(op *parsedOpcode, vm *Engine) error {
// bytes, and pushes the result, encoded as a boolean, back to the stack.
//
// Stack transformation: [... x1 x2] -> [... bool]
func opcodeEqual(op *parsedOpcode, vm *Engine) error {
func opcodeEqual(op *opcode, data []byte, vm *Engine) error {
a, err := vm.dstack.PopByteArray()
if err != nil {
return err
@ -1564,8 +1309,8 @@ func opcodeEqual(op *parsedOpcode, vm *Engine) error {
// evaluates to true. An error is returned if it does not.
//
// Stack transformation: [... x1 x2] -> [... bool] -> [...]
func opcodeEqualVerify(op *parsedOpcode, vm *Engine) error {
err := opcodeEqual(op, vm)
func opcodeEqualVerify(op *opcode, data []byte, vm *Engine) error {
err := opcodeEqual(op, data, vm)
if err == nil {
err = abstractVerify(op, vm, ErrEqualVerify)
}
@ -1576,7 +1321,7 @@ func opcodeEqualVerify(op *parsedOpcode, vm *Engine) error {
// it with its incremented value (plus 1).
//
// Stack transformation: [... x1 x2] -> [... x1 x2+1]
func opcode1Add(op *parsedOpcode, vm *Engine) error {
func opcode1Add(op *opcode, data []byte, vm *Engine) error {
m, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1590,7 +1335,7 @@ func opcode1Add(op *parsedOpcode, vm *Engine) error {
// it with its decremented value (minus 1).
//
// Stack transformation: [... x1 x2] -> [... x1 x2-1]
func opcode1Sub(op *parsedOpcode, vm *Engine) error {
func opcode1Sub(op *opcode, data []byte, vm *Engine) error {
m, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1604,7 +1349,7 @@ func opcode1Sub(op *parsedOpcode, vm *Engine) error {
// it with its negation.
//
// Stack transformation: [... x1 x2] -> [... x1 -x2]
func opcodeNegate(op *parsedOpcode, vm *Engine) error {
func opcodeNegate(op *opcode, data []byte, vm *Engine) error {
m, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1618,7 +1363,7 @@ func opcodeNegate(op *parsedOpcode, vm *Engine) error {
// it with its absolute value.
//
// Stack transformation: [... x1 x2] -> [... x1 abs(x2)]
func opcodeAbs(op *parsedOpcode, vm *Engine) error {
func opcodeAbs(op *opcode, data []byte, vm *Engine) error {
m, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1643,7 +1388,7 @@ func opcodeAbs(op *parsedOpcode, vm *Engine) error {
// Stack transformation (x2==0): [... x1 0] -> [... x1 1]
// Stack transformation (x2!=0): [... x1 1] -> [... x1 0]
// Stack transformation (x2!=0): [... x1 17] -> [... x1 0]
func opcodeNot(op *parsedOpcode, vm *Engine) error {
func opcodeNot(op *opcode, data []byte, vm *Engine) error {
m, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1663,7 +1408,7 @@ func opcodeNot(op *parsedOpcode, vm *Engine) error {
// Stack transformation (x2==0): [... x1 0] -> [... x1 0]
// Stack transformation (x2!=0): [... x1 1] -> [... x1 1]
// Stack transformation (x2!=0): [... x1 17] -> [... x1 1]
func opcode0NotEqual(op *parsedOpcode, vm *Engine) error {
func opcode0NotEqual(op *opcode, data []byte, vm *Engine) error {
m, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1680,7 +1425,7 @@ func opcode0NotEqual(op *parsedOpcode, vm *Engine) error {
// them with their sum.
//
// Stack transformation: [... x1 x2] -> [... x1+x2]
func opcodeAdd(op *parsedOpcode, vm *Engine) error {
func opcodeAdd(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1700,7 +1445,7 @@ func opcodeAdd(op *parsedOpcode, vm *Engine) error {
// entry.
//
// Stack transformation: [... x1 x2] -> [... x1-x2]
func opcodeSub(op *parsedOpcode, vm *Engine) error {
func opcodeSub(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1722,7 +1467,7 @@ func opcodeSub(op *parsedOpcode, vm *Engine) error {
// Stack transformation (x1!=0, x2==0): [... 5 0] -> [... 0]
// Stack transformation (x1==0, x2!=0): [... 0 7] -> [... 0]
// Stack transformation (x1!=0, x2!=0): [... 4 8] -> [... 1]
func opcodeBoolAnd(op *parsedOpcode, vm *Engine) error {
func opcodeBoolAnd(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1749,7 +1494,7 @@ func opcodeBoolAnd(op *parsedOpcode, vm *Engine) error {
// Stack transformation (x1!=0, x2==0): [... 5 0] -> [... 1]
// Stack transformation (x1==0, x2!=0): [... 0 7] -> [... 1]
// Stack transformation (x1!=0, x2!=0): [... 4 8] -> [... 1]
func opcodeBoolOr(op *parsedOpcode, vm *Engine) error {
func opcodeBoolOr(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1774,7 +1519,7 @@ func opcodeBoolOr(op *parsedOpcode, vm *Engine) error {
//
// Stack transformation (x1==x2): [... 5 5] -> [... 1]
// Stack transformation (x1!=x2): [... 5 7] -> [... 0]
func opcodeNumEqual(op *parsedOpcode, vm *Engine) error {
func opcodeNumEqual(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1802,8 +1547,8 @@ func opcodeNumEqual(op *parsedOpcode, vm *Engine) error {
// to true. An error is returned if it does not.
//
// Stack transformation: [... x1 x2] -> [... bool] -> [...]
func opcodeNumEqualVerify(op *parsedOpcode, vm *Engine) error {
err := opcodeNumEqual(op, vm)
func opcodeNumEqualVerify(op *opcode, data []byte, vm *Engine) error {
err := opcodeNumEqual(op, data, vm)
if err == nil {
err = abstractVerify(op, vm, ErrNumEqualVerify)
}
@ -1815,7 +1560,7 @@ func opcodeNumEqualVerify(op *parsedOpcode, vm *Engine) error {
//
// Stack transformation (x1==x2): [... 5 5] -> [... 0]
// Stack transformation (x1!=x2): [... 5 7] -> [... 1]
func opcodeNumNotEqual(op *parsedOpcode, vm *Engine) error {
func opcodeNumNotEqual(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1840,7 +1585,7 @@ func opcodeNumNotEqual(op *parsedOpcode, vm *Engine) error {
// otherwise a 0.
//
// Stack transformation: [... x1 x2] -> [... bool]
func opcodeLessThan(op *parsedOpcode, vm *Engine) error {
func opcodeLessThan(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1865,7 +1610,7 @@ func opcodeLessThan(op *parsedOpcode, vm *Engine) error {
// with a 1, otherwise a 0.
//
// Stack transformation: [... x1 x2] -> [... bool]
func opcodeGreaterThan(op *parsedOpcode, vm *Engine) error {
func opcodeGreaterThan(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1889,7 +1634,7 @@ func opcodeGreaterThan(op *parsedOpcode, vm *Engine) error {
// replaced with a 1, otherwise a 0.
//
// Stack transformation: [... x1 x2] -> [... bool]
func opcodeLessThanOrEqual(op *parsedOpcode, vm *Engine) error {
func opcodeLessThanOrEqual(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1913,7 +1658,7 @@ func opcodeLessThanOrEqual(op *parsedOpcode, vm *Engine) error {
// item, they are replaced with a 1, otherwise a 0.
//
// Stack transformation: [... x1 x2] -> [... bool]
func opcodeGreaterThanOrEqual(op *parsedOpcode, vm *Engine) error {
func opcodeGreaterThanOrEqual(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1937,7 +1682,7 @@ func opcodeGreaterThanOrEqual(op *parsedOpcode, vm *Engine) error {
// them with the minimum of the two.
//
// Stack transformation: [... x1 x2] -> [... min(x1, x2)]
func opcodeMin(op *parsedOpcode, vm *Engine) error {
func opcodeMin(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1961,7 +1706,7 @@ func opcodeMin(op *parsedOpcode, vm *Engine) error {
// them with the maximum of the two.
//
// Stack transformation: [... x1 x2] -> [... max(x1, x2)]
func opcodeMax(op *parsedOpcode, vm *Engine) error {
func opcodeMax(op *opcode, data []byte, vm *Engine) error {
v0, err := vm.dstack.PopInt()
if err != nil {
return err
@ -1989,7 +1734,7 @@ func opcodeMax(op *parsedOpcode, vm *Engine) error {
// the third-to-top item is the value to test.
//
// Stack transformation: [... x1 min max] -> [... bool]
func opcodeWithin(op *parsedOpcode, vm *Engine) error {
func opcodeWithin(op *opcode, data []byte, vm *Engine) error {
maxVal, err := vm.dstack.PopInt()
if err != nil {
return err
@ -2023,7 +1768,7 @@ func calcHash(buf []byte, hasher hash.Hash) []byte {
// replaces it with ripemd160(data).
//
// Stack transformation: [... x1] -> [... ripemd160(x1)]
func opcodeRipemd160(op *parsedOpcode, vm *Engine) error {
func opcodeRipemd160(op *opcode, data []byte, vm *Engine) error {
buf, err := vm.dstack.PopByteArray()
if err != nil {
return err
@ -2037,7 +1782,7 @@ func opcodeRipemd160(op *parsedOpcode, vm *Engine) error {
// with sha1(data).
//
// Stack transformation: [... x1] -> [... sha1(x1)]
func opcodeSha1(op *parsedOpcode, vm *Engine) error {
func opcodeSha1(op *opcode, data []byte, vm *Engine) error {
buf, err := vm.dstack.PopByteArray()
if err != nil {
return err
@ -2052,7 +1797,7 @@ func opcodeSha1(op *parsedOpcode, vm *Engine) error {
// it with sha256(data).
//
// Stack transformation: [... x1] -> [... sha256(x1)]
func opcodeSha256(op *parsedOpcode, vm *Engine) error {
func opcodeSha256(op *opcode, data []byte, vm *Engine) error {
buf, err := vm.dstack.PopByteArray()
if err != nil {
return err
@ -2067,7 +1812,7 @@ func opcodeSha256(op *parsedOpcode, vm *Engine) error {
// it with ripemd160(sha256(data)).
//
// Stack transformation: [... x1] -> [... ripemd160(sha256(x1))]
func opcodeHash160(op *parsedOpcode, vm *Engine) error {
func opcodeHash160(op *opcode, data []byte, vm *Engine) error {
buf, err := vm.dstack.PopByteArray()
if err != nil {
return err
@ -2082,7 +1827,7 @@ func opcodeHash160(op *parsedOpcode, vm *Engine) error {
// it with sha256(sha256(data)).
//
// Stack transformation: [... x1] -> [... sha256(sha256(x1))]
func opcodeHash256(op *parsedOpcode, vm *Engine) error {
func opcodeHash256(op *opcode, data []byte, vm *Engine) error {
buf, err := vm.dstack.PopByteArray()
if err != nil {
return err
@ -2096,8 +1841,8 @@ func opcodeHash256(op *parsedOpcode, vm *Engine) error {
// seen OP_CODESEPARATOR which is used during signature checking.
//
// This opcode does not change the contents of the data stack.
func opcodeCodeSeparator(op *parsedOpcode, vm *Engine) error {
vm.lastCodeSep = vm.scriptOff
func opcodeCodeSeparator(op *opcode, data []byte, vm *Engine) error {
vm.lastCodeSep = int(vm.tokenizer.ByteIndex())
return nil
}
@ -2115,7 +1860,7 @@ func opcodeCodeSeparator(op *parsedOpcode, vm *Engine) error {
// cryptographic methods against the provided public key.
//
// Stack transformation: [... signature pubkey] -> [... bool]
func opcodeCheckSig(op *parsedOpcode, vm *Engine) error {
func opcodeCheckSig(op *opcode, data []byte, vm *Engine) error {
pkBytes, err := vm.dstack.PopByteArray()
if err != nil {
return err
@ -2171,7 +1916,7 @@ func opcodeCheckSig(op *parsedOpcode, vm *Engine) error {
sigHashes = NewTxSigHashes(&vm.tx)
}
hash, err = calcWitnessSignatureHash(subScript, sigHashes, hashType,
hash, err = calcWitnessSignatureHashRaw(subScript, sigHashes, hashType,
&vm.tx, vm.txIdx, vm.inputAmount)
if err != nil {
return err
@ -2230,9 +1975,9 @@ func opcodeCheckSig(op *parsedOpcode, vm *Engine) error {
// The opcodeCheckSig function is invoked followed by opcodeVerify. See the
// documentation for each of those opcodes for more details.
//
// Stack transformation: signature pubkey] -> [... bool] -> [...]
func opcodeCheckSigVerify(op *parsedOpcode, vm *Engine) error {
err := opcodeCheckSig(op, vm)
// Stack transformation: [... signature pubkey] -> [... bool] -> [...]
func opcodeCheckSigVerify(op *opcode, data []byte, vm *Engine) error {
err := opcodeCheckSig(op, data, vm)
if err == nil {
err = abstractVerify(op, vm, ErrCheckSigVerify)
}
@ -2267,7 +2012,7 @@ type parsedSigInfo struct {
//
// Stack transformation:
// [... dummy [sig ...] numsigs [pubkey ...] numpubkeys] -> [... bool]
func opcodeCheckMultiSig(op *parsedOpcode, vm *Engine) error {
func opcodeCheckMultiSig(op *opcode, data []byte, vm *Engine) error {
numKeys, err := vm.dstack.PopInt()
if err != nil {
return err
@ -2444,7 +2189,7 @@ func opcodeCheckMultiSig(op *parsedOpcode, vm *Engine) error {
sigHashes = NewTxSigHashes(&vm.tx)
}
hash, err = calcWitnessSignatureHash(script, sigHashes, hashType,
hash, err = calcWitnessSignatureHashRaw(script, sigHashes, hashType,
&vm.tx, vm.txIdx, vm.inputAmount)
if err != nil {
return err
@ -2493,8 +2238,8 @@ func opcodeCheckMultiSig(op *parsedOpcode, vm *Engine) error {
//
// Stack transformation:
// [... dummy [sig ...] numsigs [pubkey ...] numpubkeys] -> [... bool] -> [...]
func opcodeCheckMultiSigVerify(op *parsedOpcode, vm *Engine) error {
err := opcodeCheckMultiSig(op, vm)
func opcodeCheckMultiSigVerify(op *opcode, data []byte, vm *Engine) error {
err := opcodeCheckMultiSig(op, data, vm)
if err == nil {
err = abstractVerify(op, vm, ErrCheckMultiSigVerify)
}

14
txscript/opcode_test.go
View file

@ -23,8 +23,8 @@ func TestOpcodeDisabled(t *testing.T) {
OP_LSHIFT, OP_RSHIFT,
}
for _, opcodeVal := range tests {
pop := parsedOpcode{opcode: &opcodeArray[opcodeVal], data: nil}
err := opcodeDisabled(&pop, nil)
op := &opcodeArray[opcodeVal]
err := opcodeDisabled(op, nil, nil)
if !IsErrorCode(err, ErrDisabledOpcode) {
t.Errorf("opcodeDisabled: unexpected error - got %v, "+
"want %v", err, ErrDisabledOpcode)
@ -127,8 +127,9 @@ func TestOpcodeDisasm(t *testing.T) {
expectedStr = "OP_UNKNOWN" + strconv.Itoa(opcodeVal)
}
pop := parsedOpcode{opcode: &opcodeArray[opcodeVal], data: data}
gotStr := pop.print(true)
var buf strings.Builder
disasmOpcode(&buf, &opcodeArray[opcodeVal], data, true)
gotStr := buf.String()
if gotStr != expectedStr {
t.Errorf("pop.print (opcode %x): Unexpected disasm "+
"string - got %v, want %v", opcodeVal, gotStr,
@ -193,8 +194,9 @@ func TestOpcodeDisasm(t *testing.T) {
expectedStr = "OP_UNKNOWN" + strconv.Itoa(opcodeVal)
}
pop := parsedOpcode{opcode: &opcodeArray[opcodeVal], data: data}
gotStr := pop.print(false)
var buf strings.Builder
disasmOpcode(&buf, &opcodeArray[opcodeVal], data, false)
gotStr := buf.String()
if gotStr != expectedStr {
t.Errorf("pop.print (opcode %x): Unexpected disasm "+
"string - got %v, want %v", opcodeVal, gotStr,

5
txscript/pkscript.go
View file

@ -211,11 +211,12 @@ func computeNonWitnessPkScript(sigScript []byte) (PkScript, error) {
// The redeem script will always be the last data push of the
// signature script, so we'll parse the script into opcodes to
// obtain it.
parsedOpcodes, err := parseScript(sigScript)
const scriptVersion = 0
err := checkScriptParses(scriptVersion, sigScript)
if err != nil {
return PkScript{}, err
}
redeemScript := parsedOpcodes[len(parsedOpcodes)-1].data
redeemScript := finalOpcodeData(scriptVersion, sigScript)
scriptHash := hash160(redeemScript)
script, err := payToScriptHashScript(scriptHash)

11
txscript/reference_test.go
View file

@ -836,6 +836,7 @@ func TestCalcSignatureHash(t *testing.T) {
err)
}
const scriptVersion = 0
for i, test := range tests {
if i == 0 {
// Skip first line -- contains comments only.
@ -855,16 +856,20 @@ func TestCalcSignatureHash(t *testing.T) {
}
subScript, _ := hex.DecodeString(test[1].(string))
parsedScript, err := parseScript(subScript)
if err != nil {
if err := checkScriptParses(scriptVersion, subScript); err != nil {
t.Errorf("TestCalcSignatureHash failed test #%d: "+
"Failed to parse sub-script: %v", i, err)
continue
}
hashType := SigHashType(testVecF64ToUint32(test[3].(float64)))
hash := calcSignatureHash(parsedScript, hashType, &tx,
hash, err := CalcSignatureHash(subScript, hashType, &tx,
int(test[2].(float64)))
if err != nil {
t.Errorf("TestCalcSignatureHash failed test #%d: "+
"Failed to compute sighash: %v", i, err)
continue
}
expectedHash, _ := chainhash.NewHashFromStr(test[4].(string))
if !bytes.Equal(hash, expectedHash[:]) {

621
txscript/script.go
View file

@ -1,4 +1,5 @@
// Copyright (c) 2013-2017 The btcsuite developers
// Copyright (c) 2015-2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
@ -8,6 +9,7 @@ import (
"bytes"
"encoding/binary"
"fmt"
"strings"
"time"
"github.com/btcsuite/btcd/chaincfg/chainhash"
@ -44,66 +46,48 @@ const (
// isSmallInt returns whether or not the opcode is considered a small integer,
// which is an OP_0, or OP_1 through OP_16.
func isSmallInt(op *opcode) bool {
if op.value == OP_0 || (op.value >= OP_1 && op.value <= OP_16) {
return true
}
return false
//
// NOTE: This function is only valid for version 0 opcodes. Since the function
// does not accept a script version, the results are undefined for other script
// versions.
func isSmallInt(op byte) bool {
return op == OP_0 || (op >= OP_1 && op <= OP_16)
}
// isScriptHash returns true if the script passed is a pay-to-script-hash
// transaction, false otherwise.
func isScriptHash(pops []parsedOpcode) bool {
return len(pops) == 3 &&
pops[0].opcode.value == OP_HASH160 &&
pops[1].opcode.value == OP_DATA_20 &&
pops[2].opcode.value == OP_EQUAL
// IsPayToPubKey returns true if the script is in the standard pay-to-pubkey
// (P2PK) format, false otherwise.
func IsPayToPubKey(script []byte) bool {
return isPubKeyScript(script)
}
// IsPayToPubKeyHash returns true if the script is in the standard
// pay-to-pubkey-hash (P2PKH) format, false otherwise.
func IsPayToPubKeyHash(script []byte) bool {
return isPubKeyHashScript(script)
}
// IsPayToScriptHash returns true if the script is in the standard
// pay-to-script-hash (P2SH) format, false otherwise.
//
// WARNING: This function always treats the passed script as version 0. Great
// care must be taken if introducing a new script version because it is used in
// consensus which, unfortunately as of the time of this writing, does not check
// script versions before determining if the script is a P2SH which means nodes
// on existing rules will analyze new version scripts as if they were version 0.
func IsPayToScriptHash(script []byte) bool {
pops, err := parseScript(script)
if err != nil {
return false
}
return isScriptHash(pops)
}
// isWitnessScriptHash returns true if the passed script is a
// pay-to-witness-script-hash transaction, false otherwise.
func isWitnessScriptHash(pops []parsedOpcode) bool {
return len(pops) == 2 &&
pops[0].opcode.value == OP_0 &&
pops[1].opcode.value == OP_DATA_32
return isScriptHashScript(script)
}
// IsPayToWitnessScriptHash returns true if the is in the standard
// pay-to-witness-script-hash (P2WSH) format, false otherwise.
func IsPayToWitnessScriptHash(script []byte) bool {
pops, err := parseScript(script)
if err != nil {
return false
}
return isWitnessScriptHash(pops)
return isWitnessScriptHashScript(script)
}
// IsPayToWitnessPubKeyHash returns true if the is in the standard
// pay-to-witness-pubkey-hash (P2WKH) format, false otherwise.
func IsPayToWitnessPubKeyHash(script []byte) bool {
pops, err := parseScript(script)
if err != nil {
return false
}
return isWitnessPubKeyHash(pops)
}
// isWitnessPubKeyHash returns true if the passed script is a
// pay-to-witness-pubkey-hash, and false otherwise.
func isWitnessPubKeyHash(pops []parsedOpcode) bool {
return len(pops) == 2 &&
pops[0].opcode.value == OP_0 &&
pops[1].opcode.value == OP_DATA_20
return isWitnessPubKeyHashScript(script)
}
// IsWitnessProgram returns true if the passed script is a valid witness
@ -111,163 +95,52 @@ func isWitnessPubKeyHash(pops []parsedOpcode) bool {
// witness program must be a small integer (from 0-16), followed by 2-40 bytes
// of pushed data.
func IsWitnessProgram(script []byte) bool {
// The length of the script must be between 4 and 42 bytes. The
// smallest program is the witness version, followed by a data push of
// 2 bytes. The largest allowed witness program has a data push of
// 40-bytes.
if len(script) < 4 || len(script) > 42 {
return false
}
pops, err := parseScript(script)
if err != nil {
return false
}
return isWitnessProgram(pops)
return isWitnessProgramScript(script)
}
// isWitnessProgram returns true if the passed script is a witness program, and
// false otherwise. A witness program MUST adhere to the following constraints:
// there must be exactly two pops (program version and the program itself), the
// first opcode MUST be a small integer (0-16), the push data MUST be
// canonical, and finally the size of the push data must be between 2 and 40
// bytes.
func isWitnessProgram(pops []parsedOpcode) bool {
return len(pops) == 2 &&
isSmallInt(pops[0].opcode) &&
canonicalPush(pops[1]) &&
(len(pops[1].data) >= 2 && len(pops[1].data) <= 40)
// IsNullData returns true if the passed script is a null data script, false
// otherwise.
func IsNullData(script []byte) bool {
const scriptVersion = 0
return isNullDataScript(scriptVersion, script)
}
// ExtractWitnessProgramInfo attempts to extract the witness program version,
// as well as the witness program itself from the passed script.
func ExtractWitnessProgramInfo(script []byte) (int, []byte, error) {
pops, err := parseScript(script)
if err != nil {
return 0, nil, err
}
// If at this point, the scripts doesn't resemble a witness program,
// then we'll exit early as there isn't a valid version or program to
// extract.
if !isWitnessProgram(pops) {
version, program, valid := extractWitnessProgramInfo(script)
if !valid {
return 0, nil, fmt.Errorf("script is not a witness program, " +
"unable to extract version or witness program")
}
witnessVersion := asSmallInt(pops[0].opcode)
witnessProgram := pops[1].data
return witnessVersion, witnessProgram, nil
return version, program, nil
}
// isPushOnly returns true if the script only pushes data, false otherwise.
func isPushOnly(pops []parsedOpcode) bool {
// NOTE: This function does NOT verify opcodes directly since it is
// internal and is only called with parsed opcodes for scripts that did
// not have any parse errors. Thus, consensus is properly maintained.
for _, pop := range pops {
// IsPushOnlyScript returns whether or not the passed script only pushes data
// according to the consensus definition of pushing data.
//
// WARNING: This function always treats the passed script as version 0. Great
// care must be taken if introducing a new script version because it is used in
// consensus which, unfortunately as of the time of this writing, does not check
// script versions before checking if it is a push only script which means nodes
// on existing rules will treat new version scripts as if they were version 0.
func IsPushOnlyScript(script []byte) bool {
const scriptVersion = 0
tokenizer := MakeScriptTokenizer(scriptVersion, script)
for tokenizer.Next() {
// All opcodes up to OP_16 are data push instructions.
// NOTE: This does consider OP_RESERVED to be a data push
// instruction, but execution of OP_RESERVED will fail anyways
// and matches the behavior required by consensus.
if pop.opcode.value > OP_16 {
// NOTE: This does consider OP_RESERVED to be a data push instruction,
// but execution of OP_RESERVED will fail anyway and matches the
// behavior required by consensus.
if tokenizer.Opcode() > OP_16 {
return false
}
}
return true
}
// IsPushOnlyScript returns whether or not the passed script only pushes data.
//
// False will be returned when the script does not parse.
func IsPushOnlyScript(script []byte) bool {
pops, err := parseScript(script)
if err != nil {
return false
}
return isPushOnly(pops)
}
// parseScriptTemplate is the same as parseScript but allows the passing of the
// template list for testing purposes. When there are parse errors, it returns
// the list of parsed opcodes up to the point of failure along with the error.
func parseScriptTemplate(script []byte, opcodes *[256]opcode) ([]parsedOpcode, error) {
retScript := make([]parsedOpcode, 0, len(script))
var err error
for i := 0; i < len(script); {
instr := script[i]
op := &opcodes[instr]
pop := parsedOpcode{opcode: op}
i, err = pop.checkParseableInScript(script, i)
if err != nil {
return retScript, err
}
retScript = append(retScript, pop)
}
return retScript, nil
}
// checkScriptTemplateParseable is the same as parseScriptTemplate but does not
// return the list of opcodes up until the point of failure so that this can be
// used in functions which do not necessarily have a need for the failed list of
// opcodes, such as IsUnspendable.
//
// This function returns a pointer to a byte. This byte is nil if the parsing
// has an error, or if the script length is zero. If the script length is not
// zero and parsing succeeds, then the first opcode parsed will be returned.
//
// Not returning the full opcode list up until failure also has the benefit of
// reducing GC pressure, as the list would get immediately thrown away.
func checkScriptTemplateParseable(script []byte, opcodes *[256]opcode) (*byte, error) {
var err error
// A script of length zero is an unspendable script but it is parseable.
var firstOpcode byte
var numParsedInstr uint = 0
for i := 0; i < len(script); {
instr := script[i]
op := &opcodes[instr]
pop := parsedOpcode{opcode: op}
i, err = pop.checkParseableInScript(script, i)
if err != nil {
return nil, err
}
// if this is a op_return then it is unspendable so we set the first
// parsed instruction in case it's an op_return
if numParsedInstr == 0 {
firstOpcode = pop.opcode.value
}
numParsedInstr++
}
return &firstOpcode, nil
}
// parseScript preparses the script in bytes into a list of parsedOpcodes while
// applying a number of sanity checks.
func parseScript(script []byte) ([]parsedOpcode, error) {
return parseScriptTemplate(script, &opcodeArray)
}
// unparseScript reversed the action of parseScript and returns the
// parsedOpcodes as a list of bytes
func unparseScript(pops []parsedOpcode) ([]byte, error) {
script := make([]byte, 0, len(pops))
for _, pop := range pops {
b, err := pop.bytes()
if err != nil {
return nil, err
}
script = append(script, b...)
}
return script, nil
return tokenizer.Err() == nil
}
// DisasmString formats a disassembled script for one line printing. When the
@ -275,41 +148,78 @@ func unparseScript(pops []parsedOpcode) ([]byte, error) {
// script up to the point the failure occurred along with the string '[error]'
// appended. In addition, the reason the script failed to parse is returned
// if the caller wants more information about the failure.
func DisasmString(buf []byte) (string, error) {
var disbuf bytes.Buffer
opcodes, err := parseScript(buf)
for _, pop := range opcodes {
disbuf.WriteString(pop.print(true))
//
// NOTE: This function is only valid for version 0 scripts. Since the function
// does not accept a script version, the results are undefined for other script
// versions.
func DisasmString(script []byte) (string, error) {
const scriptVersion = 0
var disbuf strings.Builder
tokenizer := MakeScriptTokenizer(scriptVersion, script)
if tokenizer.Next() {
disasmOpcode(&disbuf, tokenizer.op, tokenizer.Data(), true)
}
for tokenizer.Next() {
disbuf.WriteByte(' ')
disasmOpcode(&disbuf, tokenizer.op, tokenizer.Data(), true)
}
if disbuf.Len() > 0 {
disbuf.Truncate(disbuf.Len() - 1)
}
if err != nil {
if tokenizer.Err() != nil {
if tokenizer.ByteIndex() != 0 {
disbuf.WriteByte(' ')
}
disbuf.WriteString("[error]")
}
return disbuf.String(), err
return disbuf.String(), tokenizer.Err()
}
// removeOpcode will remove any opcode matching ``opcode'' from the opcode
// stream in pkscript
func removeOpcode(pkscript []parsedOpcode, opcode byte) []parsedOpcode {
retScript := make([]parsedOpcode, 0, len(pkscript))
for _, pop := range pkscript {
if pop.opcode.value != opcode {
retScript = append(retScript, pop)
}
// removeOpcodeRaw will return the script after removing any opcodes that match
// `opcode`. If the opcode does not appear in script, the original script will
// be returned unmodified. Otherwise, a new script will be allocated to contain
// the filtered script. This metehod assumes that the script parses
// successfully.
//
// NOTE: This function is only valid for version 0 scripts. Since the function
// does not accept a script version, the results are undefined for other script
// versions.
func removeOpcodeRaw(script []byte, opcode byte) []byte {
// Avoid work when possible.
if len(script) == 0 {
return script
}
return retScript
const scriptVersion = 0
var result []byte
var prevOffset int32
tokenizer := MakeScriptTokenizer(scriptVersion, script)
for tokenizer.Next() {
if tokenizer.Opcode() == opcode {
if result == nil {
result = make([]byte, 0, len(script))
result = append(result, script[:prevOffset]...)
}
} else if result != nil {
result = append(result, script[prevOffset:tokenizer.ByteIndex()]...)
}
prevOffset = tokenizer.ByteIndex()
}
if result == nil {
return script
}
return result
}
// canonicalPush returns true if the object is either not a push instruction
// or the push instruction contained wherein is matches the canonical form
// or using the smallest instruction to do the job. False otherwise.
func canonicalPush(pop parsedOpcode) bool {
opcode := pop.opcode.value
data := pop.data
dataLen := len(pop.data)
// isCanonicalPush returns true if the opcode is either not a push instruction
// or the data associated with the push instruction uses the smallest
// instruction to do the job. False otherwise.
//
// For example, it is possible to push a value of 1 to the stack as "OP_1",
// "OP_DATA_1 0x01", "OP_PUSHDATA1 0x01 0x01", and others, however, the first
// only takes a single byte, while the rest take more. Only the first is
// considered canonical.
func isCanonicalPush(opcode byte, data []byte) bool {
dataLen := len(data)
if opcode > OP_16 {
return true
}
@ -329,17 +239,57 @@ func canonicalPush(pop parsedOpcode) bool {
return true
}
// removeOpcodeByData will return the script minus any opcodes that would push
// the passed data to the stack.
func removeOpcodeByData(pkscript []parsedOpcode, data []byte) []parsedOpcode {
retScript := make([]parsedOpcode, 0, len(pkscript))
for _, pop := range pkscript {
if !canonicalPush(pop) || !bytes.Contains(pop.data, data) {
retScript = append(retScript, pop)
}
// removeOpcodeByData will return the script minus any opcodes that perform a
// canonical push of data that contains the passed data to remove. This
// function assumes it is provided a version 0 script as any future version of
// script should avoid this functionality since it is unncessary due to the
// signature scripts not being part of the witness-free transaction hash.
//
// WARNING: This will return the passed script unmodified unless a modification
// is necessary in which case the modified script is returned. This implies
// callers may NOT rely on being able to safely mutate either the passed or
// returned script without potentially modifying the same data.
//
// NOTE: This function is only valid for version 0 scripts. Since the function
// does not accept a script version, the results are undefined for other script
// versions.
func removeOpcodeByData(script []byte, dataToRemove []byte) []byte {
// Avoid work when possible.
if len(script) == 0 || len(dataToRemove) == 0 {
return script
}
return retScript
// Parse through the script looking for a canonical data push that contains
// the data to remove.
const scriptVersion = 0
var result []byte
var prevOffset int32
tokenizer := MakeScriptTokenizer(scriptVersion, script)
for tokenizer.Next() {
// In practice, the script will basically never actually contain the
// data since this function is only used during signature verification
// to remove the signature itself which would require some incredibly
// non-standard code to create.
//
// Thus, as an optimization, avoid allocating a new script unless there
// is actually a match that needs to be removed.
op, data := tokenizer.Opcode(), tokenizer.Data()
if isCanonicalPush(op, data) && bytes.Contains(data, dataToRemove) {
if result == nil {
fullPushLen := tokenizer.ByteIndex() - prevOffset
result = make([]byte, 0, int32(len(script))-fullPushLen)
result = append(result, script[0:prevOffset]...)
}
} else if result != nil {
result = append(result, script[prevOffset:tokenizer.ByteIndex()]...)
}
prevOffset = tokenizer.ByteIndex()
}
if result == nil {
result = script
}
return result
}
// calcHashPrevOuts calculates a single hash of all the previous outputs
@ -396,7 +346,7 @@ func calcHashOutputs(tx *wire.MsgTx) chainhash.Hash {
return chainhash.DoubleHashH(b.Bytes())
}
// calcWitnessSignatureHash computes the sighash digest of a transaction's
// calcWitnessSignatureHashRaw computes the sighash digest of a transaction's
// segwit input using the new, optimized digest calculation algorithm defined
// in BIP0143: https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki.
// This function makes use of pre-calculated sighash fragments stored within
@ -407,7 +357,7 @@ func calcHashOutputs(tx *wire.MsgTx) chainhash.Hash {
// being spent, in addition to the final transaction fee. In the case the
// wallet if fed an invalid input amount, the real sighash will differ causing
// the produced signature to be invalid.
func calcWitnessSignatureHash(subScript []parsedOpcode, sigHashes *TxSigHashes,
func calcWitnessSignatureHashRaw(scriptSig []byte, sigHashes *TxSigHashes,
hashType SigHashType, tx *wire.MsgTx, idx int, amt int64) ([]byte, error) {
// As a sanity check, ensure the passed input index for the transaction
@ -457,7 +407,7 @@ func calcWitnessSignatureHash(subScript []parsedOpcode, sigHashes *TxSigHashes,
binary.LittleEndian.PutUint32(bIndex[:], txIn.PreviousOutPoint.Index)
sigHash.Write(bIndex[:])
if isWitnessPubKeyHash(subScript) {
if isWitnessPubKeyHashScript(scriptSig) {
// The script code for a p2wkh is a length prefix varint for
// the next 25 bytes, followed by a re-creation of the original
// p2pkh pk script.
@ -465,15 +415,14 @@ func calcWitnessSignatureHash(subScript []parsedOpcode, sigHashes *TxSigHashes,
sigHash.Write([]byte{OP_DUP})
sigHash.Write([]byte{OP_HASH160})
sigHash.Write([]byte{OP_DATA_20})
sigHash.Write(subScript[1].data)
sigHash.Write(extractWitnessPubKeyHash(scriptSig))
sigHash.Write([]byte{OP_EQUALVERIFY})
sigHash.Write([]byte{OP_CHECKSIG})
} else {
// For p2wsh outputs, and future outputs, the script code is
// the original script, with all code separators removed,
// serialized with a var int length prefix.
rawScript, _ := unparseScript(subScript)
wire.WriteVarBytes(&sigHash, 0, rawScript)
wire.WriteVarBytes(&sigHash, 0, scriptSig)
}
// Next, add the input amount, and sequence number of the input being
@ -517,13 +466,12 @@ func calcWitnessSignatureHash(subScript []parsedOpcode, sigHashes *TxSigHashes,
func CalcWitnessSigHash(script []byte, sigHashes *TxSigHashes, hType SigHashType,
tx *wire.MsgTx, idx int, amt int64) ([]byte, error) {
parsedScript, err := parseScript(script)
if err != nil {
return nil, fmt.Errorf("cannot parse output script: %v", err)
const scriptVersion = 0
if err := checkScriptParses(scriptVersion, script); err != nil {
return nil, err
}
return calcWitnessSignatureHash(parsedScript, sigHashes, hType, tx, idx,
amt)
return calcWitnessSignatureHashRaw(script, sigHashes, hType, tx, idx, amt)
}
// shallowCopyTx creates a shallow copy of the transaction for use when
@ -557,18 +505,22 @@ func shallowCopyTx(tx *wire.MsgTx) wire.MsgTx {
// 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.
//
// NOTE: This function is only valid for version 0 scripts. Since the function
// does not accept a script version, the results are undefined for other script
// versions.
func CalcSignatureHash(script []byte, hashType SigHashType, tx *wire.MsgTx, idx int) ([]byte, error) {
parsedScript, err := parseScript(script)
if err != nil {
return nil, fmt.Errorf("cannot parse output script: %v", err)
const scriptVersion = 0
if err := checkScriptParses(scriptVersion, script); err != nil {
return nil, err
}
return calcSignatureHash(parsedScript, hashType, tx, idx), nil
return calcSignatureHash(script, hashType, tx, idx), nil
}
// 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 {
// calcSignatureHash computes the signature hash for the specified input of the
// target transaction observing the desired signature hash type.
func calcSignatureHash(sigScript []byte, 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).
//
@ -596,16 +548,13 @@ func calcSignatureHash(script []parsedOpcode, hashType SigHashType, tx *wire.Msg
}
// Remove all instances of OP_CODESEPARATOR from the script.
script = removeOpcode(script, OP_CODESEPARATOR)
sigScript = removeOpcodeRaw(sigScript, OP_CODESEPARATOR)
// Make a shallow copy of the transaction, zeroing out the script for
// all inputs that are not currently being processed.
txCopy := shallowCopyTx(tx)
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
@ -662,57 +611,98 @@ func calcSignatureHash(script []parsedOpcode, hashType SigHashType, tx *wire.Msg
// asSmallInt returns the passed opcode, which must be true according to
// isSmallInt(), as an integer.
func asSmallInt(op *opcode) int {
if op.value == OP_0 {
func asSmallInt(op byte) int {
if op == OP_0 {
return 0
}
return int(op.value - (OP_1 - 1))
return int(op - (OP_1 - 1))
}
// getSigOpCount is the implementation function for counting the number of
// signature operations in the script provided by pops. If precise mode is
// requested then we attempt to count the number of operations for a multisig
// op. Otherwise we use the maximum.
func getSigOpCount(pops []parsedOpcode, precise bool) int {
nSigs := 0
for i, pop := range pops {
switch pop.opcode.value {
case OP_CHECKSIG:
fallthrough
case OP_CHECKSIGVERIFY:
nSigs++
case OP_CHECKMULTISIG:
fallthrough
case OP_CHECKMULTISIGVERIFY:
// If we are being precise then look for familiar
// patterns for multisig, for now all we recognize is
// OP_1 - OP_16 to signify the number of pubkeys.
// Otherwise, we use the max of 20.
if precise && i > 0 &&
pops[i-1].opcode.value >= OP_1 &&
pops[i-1].opcode.value <= OP_16 {
nSigs += asSmallInt(pops[i-1].opcode)
// countSigOpsV0 returns the number of signature operations in the provided
// script up to the point of the first parse failure or the entire script when
// there are no parse failures. The precise flag attempts to accurately count
// the number of operations for a multisig operation versus using the maximum
// allowed.
//
// WARNING: This function always treats the passed script as version 0. Great
// care must be taken if introducing a new script version because it is used in
// consensus which, unfortunately as of the time of this writing, does not check
// script versions before counting their signature operations which means nodes
// on existing rules will count new version scripts as if they were version 0.
func countSigOpsV0(script []byte, precise bool) int {
const scriptVersion = 0
numSigOps := 0
tokenizer := MakeScriptTokenizer(scriptVersion, script)
prevOp := byte(OP_INVALIDOPCODE)
for tokenizer.Next() {
switch tokenizer.Opcode() {
case OP_CHECKSIG, OP_CHECKSIGVERIFY:
numSigOps++
case OP_CHECKMULTISIG, OP_CHECKMULTISIGVERIFY:
// Note that OP_0 is treated as the max number of sigops here in
// precise mode despite it being a valid small integer in order to
// highly discourage multisigs with zero pubkeys.
//
// Also, even though this is referred to as "precise" counting, it's
// not really precise at all due to the small int opcodes only
// covering 1 through 16 pubkeys, which means this will count any
// more than that value (e.g. 17, 18 19) as the maximum number of
// allowed pubkeys. This is, unfortunately, now part of
// the Bitcion consensus rules, due to historical
// reasons. This could be made more correct with a new
// script version, however, ideally all multisignaure
// operations in new script versions should move to
// aggregated schemes such as Schnorr instead.
if precise && prevOp >= OP_1 && prevOp <= OP_16 {
numSigOps += asSmallInt(prevOp)
} else {
nSigs += MaxPubKeysPerMultiSig
numSigOps += MaxPubKeysPerMultiSig
}
default:
// Not a sigop.
}
prevOp = tokenizer.Opcode()
}
return nSigs
return numSigOps
}
// GetSigOpCount provides a quick count of the number of signature operations
// in a script. a CHECKSIG operations counts for 1, and a CHECK_MULTISIG for 20.
// If the script fails to parse, then the count up to the point of failure is
// returned.
//
// WARNING: This function always treats the passed script as version 0. Great
// care must be taken if introducing a new script version because it is used in
// consensus which, unfortunately as of the time of this writing, does not check
// script versions before counting their signature operations which means nodes
// on existing rules will count new version scripts as if they were version 0.
func GetSigOpCount(script []byte) int {
// Don't check error since parseScript returns the parsed-up-to-error
// list of pops.
pops, _ := parseScript(script)
return getSigOpCount(pops, false)
return countSigOpsV0(script, false)
}
// finalOpcodeData returns the data associated with the final opcode in the
// script. It will return nil if the script fails to parse.
func finalOpcodeData(scriptVersion uint16, script []byte) []byte {
// Avoid unnecessary work.
if len(script) == 0 {
return nil
}
var data []byte
tokenizer := MakeScriptTokenizer(scriptVersion, script)
for tokenizer.Next() {
data = tokenizer.Data()
}
if tokenizer.Err() != nil {
return nil
}
return data
}
// GetPreciseSigOpCount returns the number of signature operations in
@ -720,44 +710,44 @@ func GetSigOpCount(script []byte) int {
// Pay-To-Script-Hash script in order to find the precise number of signature
// operations in the transaction. If the script fails to parse, then the count
// up to the point of failure is returned.
func GetPreciseSigOpCount(scriptSig, scriptPubKey []byte, bip16 bool) int {
// Don't check error since parseScript returns the parsed-up-to-error
// list of pops.
pops, _ := parseScript(scriptPubKey)
//
// WARNING: This function always treats the passed script as version 0. Great
// care must be taken if introducing a new script version because it is used in
// consensus which, unfortunately as of the time of this writing, does not check
// script versions before counting their signature operations which means nodes
// on existing rules will count new version scripts as if they were version 0.
//
// The third parameter is DEPRECATED and is unused.
func GetPreciseSigOpCount(scriptSig, scriptPubKey []byte, _ bool) int {
const scriptVersion = 0
// Treat non P2SH transactions as normal.
if !(bip16 && isScriptHash(pops)) {
return getSigOpCount(pops, true)
}
// The public key script is a pay-to-script-hash, so parse the signature
// script to get the final item. Scripts that fail to fully parse count
// as 0 signature operations.
sigPops, err := parseScript(scriptSig)
if err != nil {
return 0
// Treat non P2SH transactions as normal. Note that signature operation
// counting includes all operations up to the first parse failure.
if !isScriptHashScript(scriptPubKey) {
return countSigOpsV0(scriptPubKey, true)
}
// The signature script must only push data to the stack for P2SH to be
// a valid pair, so the signature operation count is 0 when that is not
// the case.
if !isPushOnly(sigPops) || len(sigPops) == 0 {
if len(scriptSig) == 0 || !IsPushOnlyScript(scriptSig) {
return 0
}
// The P2SH script is the last item the signature script pushes to the
// stack. When the script is empty, there are no signature operations.
shScript := sigPops[len(sigPops)-1].data
if len(shScript) == 0 {
//
// Notice that signature scripts that fail to fully parse count as 0
// signature operations unlike public key and redeem scripts.
redeemScript := finalOpcodeData(scriptVersion, scriptSig)
if len(redeemScript) == 0 {
return 0
}
// Parse the P2SH script and don't check the error since parseScript
// returns the parsed-up-to-error list of pops and the consensus rules
// dictate signature operations are counted up to the first parse
// failure.
shPops, _ := parseScript(shScript)
return getSigOpCount(shPops, true)
// Return the more precise sigops count for the redeem script. Note that
// signature operation counting includes all operations up to the first
// parse failure.
return countSigOpsV0(redeemScript, true)
}
// GetWitnessSigOpCount returns the number of signature operations generated by
@ -769,19 +759,15 @@ func GetPreciseSigOpCount(scriptSig, scriptPubKey []byte, bip16 bool) int {
func GetWitnessSigOpCount(sigScript, pkScript []byte, witness wire.TxWitness) int {
// If this is a regular witness program, then we can proceed directly
// to counting its signature operations without any further processing.
if IsWitnessProgram(pkScript) {
if isWitnessProgramScript(pkScript) {
return getWitnessSigOps(pkScript, witness)
}
// Next, we'll check the sigScript to see if this is a nested p2sh
// witness program. This is a case wherein the sigScript is actually a
// datapush of a p2wsh witness program.
sigPops, err := parseScript(sigScript)
if err != nil {
return 0
}
if IsPayToScriptHash(pkScript) && isPushOnly(sigPops) &&
IsWitnessProgram(sigScript[1:]) {
if isScriptHashScript(pkScript) && IsPushOnlyScript(sigScript) &&
len(sigScript) > 0 && isWitnessProgramScript(sigScript[1:]) {
return getWitnessSigOps(sigScript[1:], witness)
}
@ -811,26 +797,41 @@ func getWitnessSigOps(pkScript []byte, witness wire.TxWitness) int {
len(witness) > 0:
witnessScript := witness[len(witness)-1]
pops, _ := parseScript(witnessScript)
return getSigOpCount(pops, true)
return countSigOpsV0(witnessScript, true)
}
}
return 0
}
// checkScriptParses returns an error if the provided script fails to parse.
func checkScriptParses(scriptVersion uint16, script []byte) error {
tokenizer := MakeScriptTokenizer(scriptVersion, script)
for tokenizer.Next() {
// Nothing to do.
}
return tokenizer.Err()
}
// IsUnspendable returns whether the passed public key script is unspendable, or
// guaranteed to fail at execution. This allows inputs to be pruned instantly
// when entering the UTXO set.
//
// NOTE: This function is only valid for version 0 scripts. Since the function
// does not accept a script version, the results are undefined for other script
// versions.
func IsUnspendable(pkScript []byte) bool {
// Not provably unspendable
if len(pkScript) == 0 {
return false
}
firstOpcode, err := checkScriptTemplateParseable(pkScript, &opcodeArray)
if err != nil {
// The script is unspendable if starts with OP_RETURN or is guaranteed
// to fail at execution due to being larger than the max allowed script
// size.
switch {
case len(pkScript) > 0 && pkScript[0] == OP_RETURN:
return true
case len(pkScript) > MaxScriptSize:
return true
}
return firstOpcode != nil && *firstOpcode == OP_RETURN
// The script is unspendable if it is guaranteed to fail at execution.
const scriptVersion = 0
return checkScriptParses(scriptVersion, pkScript) != nil
}

3766
txscript/script_test.go
View file

File diff suppressed because it is too large Load diff

20
txscript/scriptnum.go
View file

@ -12,9 +12,21 @@ const (
maxInt32 = 1<<31 - 1
minInt32 = -1 << 31
// defaultScriptNumLen is the default number of bytes
// data being interpreted as an integer may be.
defaultScriptNumLen = 4
// maxScriptNumLen is the maximum number of bytes data being interpreted
// as an integer may be for the majority of op codes.
maxScriptNumLen = 4
// cltvMaxScriptNumLen is the maximum number of bytes data being interpreted
// as an integer may be for by-time and by-height locks as interpreted by
// CHECKLOCKTIMEVERIFY.
//
// The value comes from the fact that the current transaction locktime
// is a uint32 resulting in a maximum locktime of 2^32-1 (the year
// 2106). However, scriptNums are signed and therefore a standard
// 4-byte scriptNum would only support up to a maximum of 2^31-1 (the
// year 2038). Thus, a 5-byte scriptNum is needed since it will support
// up to 2^39-1 which allows dates beyond the current locktime limit.
cltvMaxScriptNumLen = 5
)
// scriptNum represents a numeric value used in the scripting engine with
@ -178,7 +190,7 @@ func (n scriptNum) Int32() int32 {
// before an ErrStackNumberTooBig is returned. This effectively limits the
// range of allowed values.
// WARNING: Great care should be taken if passing a value larger than
// defaultScriptNumLen, which could lead to addition and multiplication
// maxScriptNumLen, which could lead to addition and multiplication
// overflows.
//
// See the Bytes function documentation for example encodings.

126
txscript/scriptnum_test.go
View file

@ -104,35 +104,35 @@ func TestMakeScriptNum(t *testing.T) {
err error
}{
// Minimal encoding must reject negative 0.
{hexToBytes("80"), 0, defaultScriptNumLen, true, errMinimalData},
{hexToBytes("80"), 0, maxScriptNumLen, true, errMinimalData},
// Minimally encoded valid values with minimal encoding flag.
// Should not error and return expected integral number.
{nil, 0, defaultScriptNumLen, true, nil},
{hexToBytes("01"), 1, defaultScriptNumLen, true, nil},
{hexToBytes("81"), -1, defaultScriptNumLen, true, nil},
{hexToBytes("7f"), 127, defaultScriptNumLen, true, nil},
{hexToBytes("ff"), -127, defaultScriptNumLen, true, nil},
{hexToBytes("8000"), 128, defaultScriptNumLen, true, nil},
{hexToBytes("8080"), -128, defaultScriptNumLen, true, nil},
{hexToBytes("8100"), 129, defaultScriptNumLen, true, nil},
{hexToBytes("8180"), -129, defaultScriptNumLen, true, nil},
{hexToBytes("0001"), 256, defaultScriptNumLen, true, nil},
{hexToBytes("0081"), -256, defaultScriptNumLen, true, nil},
{hexToBytes("ff7f"), 32767, defaultScriptNumLen, true, nil},
{hexToBytes("ffff"), -32767, defaultScriptNumLen, true, nil},
{hexToBytes("008000"), 32768, defaultScriptNumLen, true, nil},
{hexToBytes("008080"), -32768, defaultScriptNumLen, true, nil},
{hexToBytes("ffff00"), 65535, defaultScriptNumLen, true, nil},
{hexToBytes("ffff80"), -65535, defaultScriptNumLen, true, nil},
{hexToBytes("000008"), 524288, defaultScriptNumLen, true, nil},
{hexToBytes("000088"), -524288, defaultScriptNumLen, true, nil},
{hexToBytes("000070"), 7340032, defaultScriptNumLen, true, nil},
{hexToBytes("0000f0"), -7340032, defaultScriptNumLen, true, nil},
{hexToBytes("00008000"), 8388608, defaultScriptNumLen, true, nil},
{hexToBytes("00008080"), -8388608, defaultScriptNumLen, true, nil},
{hexToBytes("ffffff7f"), 2147483647, defaultScriptNumLen, true, nil},
{hexToBytes("ffffffff"), -2147483647, defaultScriptNumLen, true, nil},
{nil, 0, maxScriptNumLen, true, nil},
{hexToBytes("01"), 1, maxScriptNumLen, true, nil},
{hexToBytes("81"), -1, maxScriptNumLen, true, nil},
{hexToBytes("7f"), 127, maxScriptNumLen, true, nil},
{hexToBytes("ff"), -127, maxScriptNumLen, true, nil},
{hexToBytes("8000"), 128, maxScriptNumLen, true, nil},
{hexToBytes("8080"), -128, maxScriptNumLen, true, nil},
{hexToBytes("8100"), 129, maxScriptNumLen, true, nil},
{hexToBytes("8180"), -129, maxScriptNumLen, true, nil},
{hexToBytes("0001"), 256, maxScriptNumLen, true, nil},
{hexToBytes("0081"), -256, maxScriptNumLen, true, nil},
{hexToBytes("ff7f"), 32767, maxScriptNumLen, true, nil},
{hexToBytes("ffff"), -32767, maxScriptNumLen, true, nil},
{hexToBytes("008000"), 32768, maxScriptNumLen, true, nil},
{hexToBytes("008080"), -32768, maxScriptNumLen, true, nil},
{hexToBytes("ffff00"), 65535, maxScriptNumLen, true, nil},
{hexToBytes("ffff80"), -65535, maxScriptNumLen, true, nil},
{hexToBytes("000008"), 524288, maxScriptNumLen, true, nil},
{hexToBytes("000088"), -524288, maxScriptNumLen, true, nil},
{hexToBytes("000070"), 7340032, maxScriptNumLen, true, nil},
{hexToBytes("0000f0"), -7340032, maxScriptNumLen, true, nil},
{hexToBytes("00008000"), 8388608, maxScriptNumLen, true, nil},
{hexToBytes("00008080"), -8388608, maxScriptNumLen, true, nil},
{hexToBytes("ffffff7f"), 2147483647, maxScriptNumLen, true, nil},
{hexToBytes("ffffffff"), -2147483647, maxScriptNumLen, true, nil},
{hexToBytes("ffffffff7f"), 549755813887, 5, true, nil},
{hexToBytes("ffffffffff"), -549755813887, 5, true, nil},
{hexToBytes("ffffffffffffff7f"), 9223372036854775807, 8, true, nil},
@ -145,50 +145,50 @@ func TestMakeScriptNum(t *testing.T) {
// Minimally encoded values that are out of range for data that
// is interpreted as script numbers with the minimal encoding
// flag set. Should error and return 0.
{hexToBytes("0000008000"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("0000008080"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("0000009000"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("0000009080"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffff00"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffff80"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("0000000001"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("0000000081"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffff00"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffff80"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffffff00"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffffff80"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffffff7f"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffffffff"), 0, defaultScriptNumLen, true, errNumTooBig},
{hexToBytes("0000008000"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("0000008080"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("0000009000"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("0000009080"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffff00"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffff80"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("0000000001"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("0000000081"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffff00"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffff80"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffffff00"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffffff80"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffffff7f"), 0, maxScriptNumLen, true, errNumTooBig},
{hexToBytes("ffffffffffffffff"), 0, maxScriptNumLen, true, errNumTooBig},
// Non-minimally encoded, but otherwise valid values with
// minimal encoding flag. Should error and return 0.
{hexToBytes("00"), 0, defaultScriptNumLen, true, errMinimalData}, // 0
{hexToBytes("0100"), 0, defaultScriptNumLen, true, errMinimalData}, // 1
{hexToBytes("7f00"), 0, defaultScriptNumLen, true, errMinimalData}, // 127
{hexToBytes("800000"), 0, defaultScriptNumLen, true, errMinimalData}, // 128
{hexToBytes("810000"), 0, defaultScriptNumLen, true, errMinimalData}, // 129
{hexToBytes("000100"), 0, defaultScriptNumLen, true, errMinimalData}, // 256
{hexToBytes("ff7f00"), 0, defaultScriptNumLen, true, errMinimalData}, // 32767
{hexToBytes("00800000"), 0, defaultScriptNumLen, true, errMinimalData}, // 32768
{hexToBytes("ffff0000"), 0, defaultScriptNumLen, true, errMinimalData}, // 65535
{hexToBytes("00000800"), 0, defaultScriptNumLen, true, errMinimalData}, // 524288
{hexToBytes("00007000"), 0, defaultScriptNumLen, true, errMinimalData}, // 7340032
{hexToBytes("0009000100"), 0, 5, true, errMinimalData}, // 16779520
{hexToBytes("00"), 0, maxScriptNumLen, true, errMinimalData}, // 0
{hexToBytes("0100"), 0, maxScriptNumLen, true, errMinimalData}, // 1
{hexToBytes("7f00"), 0, maxScriptNumLen, true, errMinimalData}, // 127
{hexToBytes("800000"), 0, maxScriptNumLen, true, errMinimalData}, // 128
{hexToBytes("810000"), 0, maxScriptNumLen, true, errMinimalData}, // 129
{hexToBytes("000100"), 0, maxScriptNumLen, true, errMinimalData}, // 256
{hexToBytes("ff7f00"), 0, maxScriptNumLen, true, errMinimalData}, // 32767
{hexToBytes("00800000"), 0, maxScriptNumLen, true, errMinimalData}, // 32768
{hexToBytes("ffff0000"), 0, maxScriptNumLen, true, errMinimalData}, // 65535
{hexToBytes("00000800"), 0, maxScriptNumLen, true, errMinimalData}, // 524288
{hexToBytes("00007000"), 0, maxScriptNumLen, true, errMinimalData}, // 7340032
{hexToBytes("0009000100"), 0, 5, true, errMinimalData}, // 16779520
// Non-minimally encoded, but otherwise valid values without
// minimal encoding flag. Should not error and return expected
// integral number.
{hexToBytes("00"), 0, defaultScriptNumLen, false, nil},
{hexToBytes("0100"), 1, defaultScriptNumLen, false, nil},
{hexToBytes("7f00"), 127, defaultScriptNumLen, false, nil},
{hexToBytes("800000"), 128, defaultScriptNumLen, false, nil},
{hexToBytes("810000"), 129, defaultScriptNumLen, false, nil},
{hexToBytes("000100"), 256, defaultScriptNumLen, false, nil},
{hexToBytes("ff7f00"), 32767, defaultScriptNumLen, false, nil},
{hexToBytes("00800000"), 32768, defaultScriptNumLen, false, nil},
{hexToBytes("ffff0000"), 65535, defaultScriptNumLen, false, nil},
{hexToBytes("00000800"), 524288, defaultScriptNumLen, false, nil},
{hexToBytes("00007000"), 7340032, defaultScriptNumLen, false, nil},
{hexToBytes("00"), 0, maxScriptNumLen, false, nil},
{hexToBytes("0100"), 1, maxScriptNumLen, false, nil},
{hexToBytes("7f00"), 127, maxScriptNumLen, false, nil},
{hexToBytes("800000"), 128, maxScriptNumLen, false, nil},
{hexToBytes("810000"), 129, maxScriptNumLen, false, nil},
{hexToBytes("000100"), 256, maxScriptNumLen, false, nil},
{hexToBytes("ff7f00"), 32767, maxScriptNumLen, false, nil},
{hexToBytes("00800000"), 32768, maxScriptNumLen, false, nil},
{hexToBytes("ffff0000"), 65535, maxScriptNumLen, false, nil},
{hexToBytes("00000800"), 524288, maxScriptNumLen, false, nil},
{hexToBytes("00007000"), 7340032, maxScriptNumLen, false, nil},
{hexToBytes("0009000100"), 16779520, 5, false, nil},
}

201
txscript/sign.go
View file

@ -22,12 +22,7 @@ func RawTxInWitnessSignature(tx *wire.MsgTx, sigHashes *TxSigHashes, idx int,
amt int64, subScript []byte, hashType SigHashType,
key *btcec.PrivateKey) ([]byte, error) {
parsedScript, err := parseScript(subScript)
if err != nil {
return nil, fmt.Errorf("cannot parse output script: %v", err)
}
hash, err := calcWitnessSignatureHash(parsedScript, sigHashes, hashType, tx,
hash, err := calcWitnessSignatureHashRaw(subScript, sigHashes, hashType, tx,
idx, amt)
if err != nil {
return nil, err
@ -212,110 +207,50 @@ func sign(chainParams *chaincfg.Params, tx *wire.MsgTx, idx int,
}
}
// mergeScripts merges sigScript and prevScript assuming they are both
// partial solutions for pkScript spending output idx of tx. class, addresses
// and nrequired are the result of extracting the addresses from pkscript.
// The return value is the best effort merging of the two scripts. Calling this
// function with addresses, class and nrequired that do not match pkScript is
// an error and results in undefined behaviour.
func mergeScripts(chainParams *chaincfg.Params, tx *wire.MsgTx, idx int,
pkScript []byte, class ScriptClass, addresses []btcutil.Address,
nRequired int, sigScript, prevScript []byte) []byte {
// TODO: the scripthash and multisig paths here are overly
// inefficient in that they will recompute already known data.
// some internal refactoring could probably make this avoid needless
// extra calculations.
switch class {
case ScriptHashTy:
// Remove the last push in the script and then recurse.
// this could be a lot less inefficient.
sigPops, err := parseScript(sigScript)
if err != nil || len(sigPops) == 0 {
return prevScript
}
prevPops, err := parseScript(prevScript)
if err != nil || len(prevPops) == 0 {
return sigScript
}
// assume that script in sigPops is the correct one, we just
// made it.
script := sigPops[len(sigPops)-1].data
// We already know this information somewhere up the stack.
class, addresses, nrequired, _ :=
ExtractPkScriptAddrs(script, chainParams)
// regenerate scripts.
sigScript, _ := unparseScript(sigPops)
prevScript, _ := unparseScript(prevPops)
// Merge
mergedScript := mergeScripts(chainParams, tx, idx, script,
class, addresses, nrequired, sigScript, prevScript)
// Reappend the script and return the result.
builder := NewScriptBuilder()
builder.AddOps(mergedScript)
builder.AddData(script)
finalScript, _ := builder.Script()
return finalScript
case MultiSigTy:
return mergeMultiSig(tx, idx, addresses, nRequired, pkScript,
sigScript, prevScript)
// It doesn't actually make sense to merge anything other than multiig
// and scripthash (because it could contain multisig). Everything else
// has either zero signature, can't be spent, or has a single signature
// which is either present or not. The other two cases are handled
// above. In the conflict case here we just assume the longest is
// correct (this matches behaviour of the reference implementation).
default:
if len(sigScript) > len(prevScript) {
return sigScript
}
return prevScript
}
}
// mergeMultiSig combines the two signature scripts sigScript and prevScript
// that both provide signatures for pkScript in output idx of tx. addresses
// and nRequired should be the results from extracting the addresses from
// pkScript. Since this function is internal only we assume that the arguments
// have come from other functions internally and thus are all consistent with
// each other, behaviour is undefined if this contract is broken.
//
// NOTE: This function is only valid for version 0 scripts. Since the function
// does not accept a script version, the results are undefined for other script
// versions.
func mergeMultiSig(tx *wire.MsgTx, idx int, addresses []btcutil.Address,
nRequired int, pkScript, sigScript, prevScript []byte) []byte {
// This is an internal only function and we already parsed this script
// as ok for multisig (this is how we got here), so if this fails then
// all assumptions are broken and who knows which way is up?
pkPops, _ := parseScript(pkScript)
sigPops, err := parseScript(sigScript)
if err != nil || len(sigPops) == 0 {
// Nothing to merge if either the new or previous signature scripts are
// empty.
if len(sigScript) == 0 {
return prevScript
}
prevPops, err := parseScript(prevScript)
if err != nil || len(prevPops) == 0 {
if len(prevScript) == 0 {
return sigScript
}
// Convenience function to avoid duplication.
extractSigs := func(pops []parsedOpcode, sigs [][]byte) [][]byte {
for _, pop := range pops {
if len(pop.data) != 0 {
sigs = append(sigs, pop.data)
var possibleSigs [][]byte
extractSigs := func(script []byte) error {
const scriptVersion = 0
tokenizer := MakeScriptTokenizer(scriptVersion, script)
for tokenizer.Next() {
if data := tokenizer.Data(); len(data) != 0 {
possibleSigs = append(possibleSigs, data)
}
}
return sigs
return tokenizer.Err()
}
possibleSigs := make([][]byte, 0, len(sigPops)+len(prevPops))
possibleSigs = extractSigs(sigPops, possibleSigs)
possibleSigs = extractSigs(prevPops, possibleSigs)
// Attempt to extract signatures from the two scripts. Return the other
// script that is intended to be merged in the case signature extraction
// fails for some reason.
if err := extractSigs(sigScript); err != nil {
return prevScript
}
if err := extractSigs(prevScript); err != nil {
return sigScript
}
// Now we need to match the signatures to pubkeys, the only real way to
// do that is to try to verify them all and match it to the pubkey
@ -345,7 +280,7 @@ sigLoop:
// however, assume no sigs etc are in the script since that
// would make the transaction nonstandard and thus not
// MultiSigTy, so we just need to hash the full thing.
hash := calcSignatureHash(pkPops, hashType, tx, idx)
hash := calcSignatureHash(pkScript, hashType, tx, idx)
for _, addr := range addresses {
// All multisig addresses should be pubkey addresses
@ -394,6 +329,81 @@ sigLoop:
return script
}
// mergeScripts merges sigScript and prevScript assuming they are both
// partial solutions for pkScript spending output idx of tx. class, addresses
// and nrequired are the result of extracting the addresses from pkscript.
// The return value is the best effort merging of the two scripts. Calling this
// function with addresses, class and nrequired that do not match pkScript is
// an error and results in undefined behaviour.
//
// NOTE: This function is only valid for version 0 scripts. Since the function
// does not accept a script version, the results are undefined for other script
// versions.
func mergeScripts(chainParams *chaincfg.Params, tx *wire.MsgTx, idx int,
pkScript []byte, class ScriptClass, addresses []btcutil.Address,
nRequired int, sigScript, prevScript []byte) []byte {
// TODO(oga) the scripthash and multisig paths here are overly
// inefficient in that they will recompute already known data.
// some internal refactoring could probably make this avoid needless
// extra calculations.
const scriptVersion = 0
switch class {
case ScriptHashTy:
// Nothing to merge if either the new or previous signature
// scripts are empty or fail to parse.
if len(sigScript) == 0 ||
checkScriptParses(scriptVersion, sigScript) != nil {
return prevScript
}
if len(prevScript) == 0 ||
checkScriptParses(scriptVersion, prevScript) != nil {
return sigScript
}
// Remove the last push in the script and then recurse.
// this could be a lot less inefficient.
//
// Assume that final script is the correct one since it was just
// made and it is a pay-to-script-hash.
script := finalOpcodeData(scriptVersion, sigScript)
// We already know this information somewhere up the stack,
// therefore the error is ignored.
class, addresses, nrequired, _ :=
ExtractPkScriptAddrs(script, chainParams)
// Merge
mergedScript := mergeScripts(chainParams, tx, idx, script,
class, addresses, nrequired, sigScript, prevScript)
// Reappend the script and return the result.
builder := NewScriptBuilder()
builder.AddOps(mergedScript)
builder.AddData(script)
finalScript, _ := builder.Script()
return finalScript
case MultiSigTy:
return mergeMultiSig(tx, idx, addresses, nRequired, pkScript,
sigScript, prevScript)
// It doesn't actually make sense to merge anything other than multiig
// and scripthash (because it could contain multisig). Everything else
// has either zero signature, can't be spent, or has a single signature
// which is either present or not. The other two cases are handled
// above. In the conflict case here we just assume the longest is
// correct (this matches behaviour of the reference implementation).
default:
if len(sigScript) > len(prevScript) {
return sigScript
}
return prevScript
}
}
// KeyDB is an interface type provided to SignTxOutput, it encapsulates
// any user state required to get the private keys for an address.
type KeyDB interface {
@ -404,8 +414,7 @@ type KeyDB interface {
type KeyClosure func(btcutil.Address) (*btcec.PrivateKey, bool, error)
// GetKey implements KeyDB by returning the result of calling the closure.
func (kc KeyClosure) GetKey(address btcutil.Address) (*btcec.PrivateKey,
bool, error) {
func (kc KeyClosure) GetKey(address btcutil.Address) (*btcec.PrivateKey, bool, error) {
return kc(address)
}
@ -430,6 +439,10 @@ func (sc ScriptClosure) GetScript(address btcutil.Address) ([]byte, error) {
// getScript. If previousScript is provided then the results in previousScript
// will be merged in a type-dependent manner with the newly generated.
// signature script.
//
// NOTE: This function is only valid for version 0 scripts. Since the function
// does not accept a script version, the results are undefined for other script
// versions.
func SignTxOutput(chainParams *chaincfg.Params, tx *wire.MsgTx, idx int,
pkScript []byte, hashType SigHashType, kdb KeyDB, sdb ScriptDB,
previousScript []byte) ([]byte, error) {

4
txscript/stack.go
View file

@ -86,7 +86,7 @@ func (s *stack) PopInt() (scriptNum, error) {
return 0, err
}
return makeScriptNum(so, s.verifyMinimalData, defaultScriptNumLen)
return makeScriptNum(so, s.verifyMinimalData, maxScriptNumLen)
}
// PopBool pops the value off the top of the stack, converts it into a bool, and
@ -123,7 +123,7 @@ func (s *stack) PeekInt(idx int32) (scriptNum, error) {
return 0, err
}
return makeScriptNum(so, s.verifyMinimalData, defaultScriptNumLen)
return makeScriptNum(so, s.verifyMinimalData, maxScriptNumLen)
}
// PeekBool returns the Nth item on the stack as a bool without removing it.

913
txscript/standard.go
View file

File diff suppressed because it is too large Load diff

8
txscript/standard_test.go
View file

@ -832,7 +832,7 @@ func TestCalcMultiSigStats(t *testing.T) {
name: "short script",
script: "0x046708afdb0fe5548271967f1a67130b7105cd6a828" +
"e03909a67962e0ea1f61d",
err: scriptError(ErrMalformedPush, ""),
err: scriptError(ErrNotMultisigScript, ""),
},
{
name: "stack underflow",
@ -843,11 +843,7 @@ func TestCalcMultiSigStats(t *testing.T) {
},
{
name: "multisig script",
script: "0 DATA_72 0x30450220106a3e4ef0b51b764a2887226" +
"2ffef55846514dacbdcbbdd652c849d395b4384022100" +
"e03ae554c3cbb40600d31dd46fc33f25e47bf8525b1fe" +
"07282e3b6ecb5f3bb2801 CODESEPARATOR 1 DATA_33 " +
"0x0232abdc893e7f0631364d7fd01cb33d24da45329a0" +
script: "1 DATA_33 0x0232abdc893e7f0631364d7fd01cb33d24da45329a0" +
"0357b3a7886211ab414d55a 1 CHECKMULTISIG",
err: nil,
},

186
txscript/tokenizer.go Normal file
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@ -0,0 +1,186 @@
// Copyright (c) 2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package txscript
import (
"encoding/binary"
"fmt"
)
// opcodeArrayRef is used to break initialization cycles.
var opcodeArrayRef *[256]opcode
func init() {
opcodeArrayRef = &opcodeArray
}
// ScriptTokenizer provides a facility for easily and efficiently tokenizing
// transaction scripts without creating allocations. Each successive opcode is
// parsed with the Next function, which returns false when iteration is
// complete, either due to successfully tokenizing the entire script or
// encountering a parse error. In the case of failure, the Err function may be
// used to obtain the specific parse error.
//
// Upon successfully parsing an opcode, the opcode and data associated with it
// may be obtained via the Opcode and Data functions, respectively.
//
// The ByteIndex function may be used to obtain the tokenizer's current offset
// into the raw script.
type ScriptTokenizer struct {
script []byte
version uint16
offset int32
op *opcode
data []byte
err error
}
// Done returns true when either all opcodes have been exhausted or a parse
// failure was encountered and therefore the state has an associated error.
func (t *ScriptTokenizer) Done() bool {
return t.err != nil || t.offset >= int32(len(t.script))
}
// Next attempts to parse the next opcode and returns whether or not it was
// successful. It will not be successful if invoked when already at the end of
// the script, a parse failure is encountered, or an associated error already
// exists due to a previous parse failure.
//
// In the case of a true return, the parsed opcode and data can be obtained with
// the associated functions and the offset into the script will either point to
// the next opcode or the end of the script if the final opcode was parsed.
//
// In the case of a false return, the parsed opcode and data will be the last
// successfully parsed values (if any) and the offset into the script will
// either point to the failing opcode or the end of the script if the function
// was invoked when already at the end of the script.
//
// Invoking this function when already at the end of the script is not
// considered an error and will simply return false.
func (t *ScriptTokenizer) Next() bool {
if t.Done() {
return false
}
op := &opcodeArrayRef[t.script[t.offset]]
switch {
// No additional data. Note that some of the opcodes, notably OP_1NEGATE,
// OP_0, and OP_[1-16] represent the data themselves.
case op.length == 1:
t.offset++
t.op = op
t.data = nil
return true
// Data pushes of specific lengths -- OP_DATA_[1-75].
case op.length > 1:
script := t.script[t.offset:]
if len(script) < op.length {
str := fmt.Sprintf("opcode %s requires %d bytes, but script only "+
"has %d remaining", op.name, op.length, len(script))
t.err = scriptError(ErrMalformedPush, str)
return false
}
// Move the offset forward and set the opcode and data accordingly.
t.offset += int32(op.length)
t.op = op
t.data = script[1:op.length]
return true
// Data pushes with parsed lengths -- OP_PUSHDATA{1,2,4}.
case op.length < 0:
script := t.script[t.offset+1:]
if len(script) < -op.length {
str := fmt.Sprintf("opcode %s requires %d bytes, but script only "+
"has %d remaining", op.name, -op.length, len(script))
t.err = scriptError(ErrMalformedPush, str)
return false
}
// Next -length bytes are little endian length of data.
var dataLen int32
switch op.length {
case -1:
dataLen = int32(script[0])
case -2:
dataLen = int32(binary.LittleEndian.Uint16(script[:2]))
case -4:
dataLen = int32(binary.LittleEndian.Uint32(script[:4]))
default:
// In practice it should be impossible to hit this
// check as each op code is predefined, and only uses
// the specified lengths.
str := fmt.Sprintf("invalid opcode length %d", op.length)
t.err = scriptError(ErrMalformedPush, str)
return false
}
// Move to the beginning of the data.
script = script[-op.length:]
// Disallow entries that do not fit script or were sign extended.
if dataLen > int32(len(script)) || dataLen < 0 {
str := fmt.Sprintf("opcode %s pushes %d bytes, but script only "+
"has %d remaining", op.name, dataLen, len(script))
t.err = scriptError(ErrMalformedPush, str)
return false
}
// Move the offset forward and set the opcode and data accordingly.
t.offset += 1 + int32(-op.length) + dataLen
t.op = op
t.data = script[:dataLen]
return true
}
// The only remaining case is an opcode with length zero which is
// impossible.
panic("unreachable")
}
// Script returns the full script associated with the tokenizer.
func (t *ScriptTokenizer) Script() []byte {
return t.script
}
// ByteIndex returns the current offset into the full script that will be parsed
// next and therefore also implies everything before it has already been parsed.
func (t *ScriptTokenizer) ByteIndex() int32 {
return t.offset
}
// Opcode returns the current opcode associated with the tokenizer.
func (t *ScriptTokenizer) Opcode() byte {
return t.op.value
}
// Data returns the data associated with the most recently successfully parsed
// opcode.
func (t *ScriptTokenizer) Data() []byte {
return t.data
}
// Err returns any errors currently associated with the tokenizer. This will
// only be non-nil in the case a parsing error was encountered.
func (t *ScriptTokenizer) Err() error {
return t.err
}
// MakeScriptTokenizer returns a new instance of a script tokenizer. Passing
// an unsupported script version will result in the returned tokenizer
// immediately having an err set accordingly.
//
// See the docs for ScriptTokenizer for more details.
func MakeScriptTokenizer(scriptVersion uint16, script []byte) ScriptTokenizer {
// Only version 0 scripts are currently supported.
var err error
if scriptVersion != 0 {
str := fmt.Sprintf("script version %d is not supported", scriptVersion)
err = scriptError(ErrUnsupportedScriptVersion, str)
}
return ScriptTokenizer{version: scriptVersion, script: script, err: err}
}

259
txscript/tokenizer_test.go Normal file
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@ -0,0 +1,259 @@
// Copyright (c) 2019 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package txscript
import (
"bytes"
"fmt"
"testing"
)
// TestScriptTokenizer ensures a wide variety of behavior provided by the script
// tokenizer performs as expected.
func TestScriptTokenizer(t *testing.T) {
t.Skip()
type expectedResult struct {
op byte // expected parsed opcode
data []byte // expected parsed data
index int32 // expected index into raw script after parsing token
}
type tokenizerTest struct {
name string // test description
script []byte // the script to tokenize
expected []expectedResult // the expected info after parsing each token
finalIdx int32 // the expected final byte index
err error // expected error
}
// Add both positive and negative tests for OP_DATA_1 through OP_DATA_75.
const numTestsHint = 100 // Make prealloc linter happy.
tests := make([]tokenizerTest, 0, numTestsHint)
for op := byte(OP_DATA_1); op < OP_DATA_75; op++ {
data := bytes.Repeat([]byte{0x01}, int(op))
tests = append(tests, tokenizerTest{
name: fmt.Sprintf("OP_DATA_%d", op),
script: append([]byte{op}, data...),
expected: []expectedResult{{op, data, 1 + int32(op)}},
finalIdx: 1 + int32(op),
err: nil,
})
// Create test that provides one less byte than the data push requires.
tests = append(tests, tokenizerTest{
name: fmt.Sprintf("short OP_DATA_%d", op),
script: append([]byte{op}, data[1:]...),
expected: nil,
finalIdx: 0,
err: scriptError(ErrMalformedPush, ""),
})
}
// Add both positive and negative tests for OP_PUSHDATA{1,2,4}.
data := mustParseShortForm("0x01{76}")
tests = append(tests, []tokenizerTest{{
name: "OP_PUSHDATA1",
script: mustParseShortForm("OP_PUSHDATA1 0x4c 0x01{76}"),
expected: []expectedResult{{OP_PUSHDATA1, data, 2 + int32(len(data))}},
finalIdx: 2 + int32(len(data)),
err: nil,
}, {
name: "OP_PUSHDATA1 no data length",
script: mustParseShortForm("OP_PUSHDATA1"),
expected: nil,
finalIdx: 0,
err: scriptError(ErrMalformedPush, ""),
}, {
name: "OP_PUSHDATA1 short data by 1 byte",
script: mustParseShortForm("OP_PUSHDATA1 0x4c 0x01{75}"),
expected: nil,
finalIdx: 0,
err: scriptError(ErrMalformedPush, ""),
}, {
name: "OP_PUSHDATA2",
script: mustParseShortForm("OP_PUSHDATA2 0x4c00 0x01{76}"),
expected: []expectedResult{{OP_PUSHDATA2, data, 3 + int32(len(data))}},
finalIdx: 3 + int32(len(data)),
err: nil,
}, {
name: "OP_PUSHDATA2 no data length",
script: mustParseShortForm("OP_PUSHDATA2"),
expected: nil,
finalIdx: 0,
err: scriptError(ErrMalformedPush, ""),
}, {
name: "OP_PUSHDATA2 short data by 1 byte",
script: mustParseShortForm("OP_PUSHDATA2 0x4c00 0x01{75}"),
expected: nil,
finalIdx: 0,
err: scriptError(ErrMalformedPush, ""),
}, {
name: "OP_PUSHDATA4",
script: mustParseShortForm("OP_PUSHDATA4 0x4c000000 0x01{76}"),
expected: []expectedResult{{OP_PUSHDATA4, data, 5 + int32(len(data))}},
finalIdx: 5 + int32(len(data)),
err: nil,
}, {
name: "OP_PUSHDATA4 no data length",
script: mustParseShortForm("OP_PUSHDATA4"),
expected: nil,
finalIdx: 0,
err: scriptError(ErrMalformedPush, ""),
}, {
name: "OP_PUSHDATA4 short data by 1 byte",
script: mustParseShortForm("OP_PUSHDATA4 0x4c000000 0x01{75}"),
expected: nil,
finalIdx: 0,
err: scriptError(ErrMalformedPush, ""),
}}...)
// Add tests for OP_0, and OP_1 through OP_16 (small integers/true/false).
opcodes := []byte{OP_0}
for op := byte(OP_1); op < OP_16; op++ {
opcodes = append(opcodes, op)
}
for _, op := range opcodes {
tests = append(tests, tokenizerTest{
name: fmt.Sprintf("OP_%d", op),
script: []byte{op},
expected: []expectedResult{{op, nil, 1}},
finalIdx: 1,
err: nil,
})
}
// Add various positive and negative tests for multi-opcode scripts.
tests = append(tests, []tokenizerTest{{
name: "pay-to-pubkey-hash",
script: mustParseShortForm("DUP HASH160 DATA_20 0x01{20} EQUAL CHECKSIG"),
expected: []expectedResult{
{OP_DUP, nil, 1}, {OP_HASH160, nil, 2},
{OP_DATA_20, mustParseShortForm("0x01{20}"), 23},
{OP_EQUAL, nil, 24}, {OP_CHECKSIG, nil, 25},
},
finalIdx: 25,
err: nil,
}, {
name: "almost pay-to-pubkey-hash (short data)",
script: mustParseShortForm("DUP HASH160 DATA_20 0x01{17} EQUAL CHECKSIG"),
expected: []expectedResult{
{OP_DUP, nil, 1}, {OP_HASH160, nil, 2},
},
finalIdx: 2,
err: scriptError(ErrMalformedPush, ""),
}, {
name: "almost pay-to-pubkey-hash (overlapped data)",
script: mustParseShortForm("DUP HASH160 DATA_20 0x01{19} EQUAL CHECKSIG"),
expected: []expectedResult{
{OP_DUP, nil, 1}, {OP_HASH160, nil, 2},
{OP_DATA_20, mustParseShortForm("0x01{19} EQUAL"), 23},
{OP_CHECKSIG, nil, 24},
},
finalIdx: 24,
err: nil,
}, {
name: "pay-to-script-hash",
script: mustParseShortForm("HASH160 DATA_20 0x01{20} EQUAL"),
expected: []expectedResult{
{OP_HASH160, nil, 1},
{OP_DATA_20, mustParseShortForm("0x01{20}"), 22},
{OP_EQUAL, nil, 23},
},
finalIdx: 23,
err: nil,
}, {
name: "almost pay-to-script-hash (short data)",
script: mustParseShortForm("HASH160 DATA_20 0x01{18} EQUAL"),
expected: []expectedResult{
{OP_HASH160, nil, 1},
},
finalIdx: 1,
err: scriptError(ErrMalformedPush, ""),
}, {
name: "almost pay-to-script-hash (overlapped data)",
script: mustParseShortForm("HASH160 DATA_20 0x01{19} EQUAL"),
expected: []expectedResult{
{OP_HASH160, nil, 1},
{OP_DATA_20, mustParseShortForm("0x01{19} EQUAL"), 22},
},
finalIdx: 22,
err: nil,
}}...)
const scriptVersion = 0
for _, test := range tests {
tokenizer := MakeScriptTokenizer(scriptVersion, test.script)
var opcodeNum int
for tokenizer.Next() {
// Ensure Next never returns true when there is an error set.
if err := tokenizer.Err(); err != nil {
t.Fatalf("%q: Next returned true when tokenizer has err: %v",
test.name, err)
}
// Ensure the test data expects a token to be parsed.
op := tokenizer.Opcode()
data := tokenizer.Data()
if opcodeNum >= len(test.expected) {
t.Fatalf("%q: unexpected token '%d' (data: '%x')", test.name,
op, data)
}
expected := &test.expected[opcodeNum]
// Ensure the opcode and data are the expected values.
if op != expected.op {
t.Fatalf("%q: unexpected opcode -- got %v, want %v", test.name,
op, expected.op)
}
if !bytes.Equal(data, expected.data) {
t.Fatalf("%q: unexpected data -- got %x, want %x", test.name,
data, expected.data)
}
tokenizerIdx := tokenizer.ByteIndex()
if tokenizerIdx != expected.index {
t.Fatalf("%q: unexpected byte index -- got %d, want %d",
test.name, tokenizerIdx, expected.index)
}
opcodeNum++
}
// Ensure the tokenizer claims it is done. This should be the case
// regardless of whether or not there was a parse error.
if !tokenizer.Done() {
t.Fatalf("%q: tokenizer claims it is not done", test.name)
}
// Ensure the error is as expected.
if test.err == nil && tokenizer.Err() != nil {
t.Fatalf("%q: unexpected tokenizer err -- got %v, want nil",
test.name, tokenizer.Err())
} else if test.err != nil {
if !IsErrorCode(tokenizer.Err(), test.err.(Error).ErrorCode) {
t.Fatalf("%q: unexpected tokenizer err -- got %v, want %v",
test.name, tokenizer.Err(), test.err.(Error).ErrorCode)
}
}
// Ensure the final index is the expected value.
tokenizerIdx := tokenizer.ByteIndex()
if tokenizerIdx != test.finalIdx {
t.Fatalf("%q: unexpected final byte index -- got %d, want %d",
test.name, tokenizerIdx, test.finalIdx)
}
}
}
// TestScriptTokenizerUnsupportedVersion ensures the tokenizer fails immediately
// with an unsupported script version.
func TestScriptTokenizerUnsupportedVersion(t *testing.T) {
const scriptVersion = 65535
tokenizer := MakeScriptTokenizer(scriptVersion, nil)
if !IsErrorCode(tokenizer.Err(), ErrUnsupportedScriptVersion) {
t.Fatalf("script tokenizer did not error with unsupported version")
}
}