// validateSigScripts executes the signature script of the tx input with the
// given index, returning an error if it fails.
func validateSigScript(msgtx *wire.MsgTx, idx int, pkScript []byte) error {
vm, err := txscript.NewEngine(pkScript, msgtx, idx,
txscript.StandardVerifyFlags, nil)
if err != nil {
return newError(ErrTxSigning, "cannot create script engine", err)
}
if err = vm.Execute(); err != nil {
return newError(ErrTxSigning, "cannot validate tx signature", err)
}
return nil
}
func validateMsgTx(msgtx *wire.MsgTx, prevOutputs []wtxmgr.Credit) error {
for i := range msgtx.TxIn {
vm, err := txscript.NewEngine(prevOutputs[i].PkScript,
msgtx, i, txscript.StandardVerifyFlags, nil)
if err != nil {
return fmt.Errorf("cannot create script engine: %s", err)
}
if err = vm.Execute(); err != nil {
return fmt.Errorf("cannot validate transaction: %s", err)
}
}
return nil
}
// TestInvalidFlagCombinations ensures the script engine returns the expected
// error when disallowed flag combinations are specified.
func TestInvalidFlagCombinations(t *testing.T) {
t.Parallel()
tests := []txscript.ScriptFlags{
txscript.ScriptVerifyCleanStack,
}
// tx with almost empty scripts.
tx := &wire.MsgTx{
Version: 1,
TxIn: []*wire.TxIn{
{
PreviousOutPoint: wire.OutPoint{
Hash: wire.ShaHash([32]byte{
0xc9, 0x97, 0xa5, 0xe5,
0x6e, 0x10, 0x41, 0x02,
0xfa, 0x20, 0x9c, 0x6a,
0x85, 0x2d, 0xd9, 0x06,
0x60, 0xa2, 0x0b, 0x2d,
0x9c, 0x35, 0x24, 0x23,
0xed, 0xce, 0x25, 0x85,
0x7f, 0xcd, 0x37, 0x04,
}),
Index: 0,
},
SignatureScript: []uint8{txscript.OP_NOP},
Sequence: 4294967295,
},
},
TxOut: []*wire.TxOut{
{
Value: 1000000000,
PkScript: nil,
},
},
LockTime: 0,
}
pkScript := []byte{txscript.OP_NOP}
for i, test := range tests {
_, err := txscript.NewEngine(pkScript, tx, 0, test, nil)
if err != txscript.ErrInvalidFlags {
t.Fatalf("TestInvalidFlagCombinations #%d unexpected "+
"error: %v", i, err)
}
}
}
func checkScripts(msg string, tx *wire.MsgTx, idx int, sigScript, pkScript []byte) error {
tx.TxIn[idx].SignatureScript = sigScript
vm, err := txscript.NewEngine(pkScript, tx, idx,
txscript.ScriptBip16|txscript.ScriptVerifyDERSignatures, nil)
if err != nil {
return fmt.Errorf("failed to make script engine for %s: %v",
msg, err)
}
err = vm.Execute()
if err != nil {
return fmt.Errorf("invalid script signature for %s: %v", msg,
err)
}
return nil
}
// This example demonstrates manually creating and signing a redeem transaction.
func ExampleSignTxOutput() {
// Ordinarily the private key would come from whatever storage mechanism
// is being used, but for this example just hard code it.
privKeyBytes, err := hex.DecodeString("22a47fa09a223f2aa079edf85a7c2" +
"d4f8720ee63e502ee2869afab7de234b80c")
if err != nil {
fmt.Println(err)
return
}
privKey, pubKey := btcec.PrivKeyFromBytes(btcec.S256(), privKeyBytes)
pubKeyHash := coinutil.Hash160(pubKey.SerializeCompressed())
addr, err := coinutil.NewAddressPubKeyHash(pubKeyHash,
&chaincfg.MainNetParams)
if err != nil {
fmt.Println(err)
return
}
// For this example, create a fake transaction that represents what
// would ordinarily be the real transaction that is being spent. It
// contains a single output that pays to address in the amount of 1 BTC.
originTx := wire.NewMsgTx()
prevOut := wire.NewOutPoint(&wire.ShaHash{}, ^uint32(0))
txIn := wire.NewTxIn(prevOut, []byte{txscript.OP_0, txscript.OP_0})
originTx.AddTxIn(txIn)
pkScript, err := txscript.PayToAddrScript(addr)
if err != nil {
fmt.Println(err)
return
}
txOut := wire.NewTxOut(100000000, pkScript)
originTx.AddTxOut(txOut)
originTxHash := originTx.TxSha()
// Create the transaction to redeem the fake transaction.
redeemTx := wire.NewMsgTx()
// Add the input(s) the redeeming transaction will spend. There is no
// signature script at this point since it hasn't been created or signed
// yet, hence nil is provided for it.
prevOut = wire.NewOutPoint(&originTxHash, 0)
txIn = wire.NewTxIn(prevOut, nil)
redeemTx.AddTxIn(txIn)
// Ordinarily this would contain that actual destination of the funds,
// but for this example don't bother.
txOut = wire.NewTxOut(0, nil)
redeemTx.AddTxOut(txOut)
// Sign the redeeming transaction.
lookupKey := func(a coinutil.Address) (*btcec.PrivateKey, bool, error) {
// Ordinarily this function would involve looking up the private
// key for the provided address, but since the only thing being
// signed in this example uses the address associated with the
// private key from above, simply return it with the compressed
// flag set since the address is using the associated compressed
// public key.
//
// NOTE: If you want to prove the code is actually signing the
// transaction properly, uncomment the following line which
// intentionally returns an invalid key to sign with, which in
// turn will result in a failure during the script execution
// when verifying the signature.
//
// privKey.D.SetInt64(12345)
//
return privKey, true, nil
}
// Notice that the script database parameter is nil here since it isn't
// used. It must be specified when pay-to-script-hash transactions are
// being signed.
sigScript, err := txscript.SignTxOutput(&chaincfg.MainNetParams,
redeemTx, 0, originTx.TxOut[0].PkScript, txscript.SigHashAll,
txscript.KeyClosure(lookupKey), nil, nil)
if err != nil {
fmt.Println(err)
return
}
redeemTx.TxIn[0].SignatureScript = sigScript
// Prove that the transaction has been validly signed by executing the
// script pair.
flags := txscript.ScriptBip16 | txscript.ScriptVerifyDERSignatures |
txscript.ScriptStrictMultiSig |
txscript.ScriptDiscourageUpgradableNops
vm, err := txscript.NewEngine(originTx.TxOut[0].PkScript, redeemTx, 0,
flags, nil)
if err != nil {
fmt.Println(err)
return
}
if err := vm.Execute(); err != nil {
fmt.Println(err)
return
}
fmt.Println("Transaction successfully signed")
// Output:
// Transaction successfully signed
}
// TestCheckErrorCondition tests the execute early test in CheckErrorCondition()
// since most code paths are tested elsewhere.
func TestCheckErrorCondition(t *testing.T) {
t.Parallel()
// tx with almost empty scripts.
tx := &wire.MsgTx{
Version: 1,
TxIn: []*wire.TxIn{
{
PreviousOutPoint: wire.OutPoint{
Hash: wire.ShaHash([32]byte{
0xc9, 0x97, 0xa5, 0xe5,
0x6e, 0x10, 0x41, 0x02,
0xfa, 0x20, 0x9c, 0x6a,
0x85, 0x2d, 0xd9, 0x06,
0x60, 0xa2, 0x0b, 0x2d,
0x9c, 0x35, 0x24, 0x23,
0xed, 0xce, 0x25, 0x85,
0x7f, 0xcd, 0x37, 0x04,
}),
Index: 0,
},
SignatureScript: []uint8{},
Sequence: 4294967295,
},
},
TxOut: []*wire.TxOut{
{
Value: 1000000000,
PkScript: nil,
},
},
LockTime: 0,
}
pkScript := []byte{
txscript.OP_NOP,
txscript.OP_NOP,
txscript.OP_NOP,
txscript.OP_NOP,
txscript.OP_NOP,
txscript.OP_NOP,
txscript.OP_NOP,
txscript.OP_NOP,
txscript.OP_NOP,
txscript.OP_NOP,
txscript.OP_TRUE,
}
vm, err := txscript.NewEngine(pkScript, tx, 0, 0, nil)
if err != nil {
t.Errorf("failed to create script: %v", err)
}
for i := 0; i < len(pkScript)-1; i++ {
done, err := vm.Step()
if err != nil {
t.Errorf("failed to step %dth time: %v", i, err)
return
}
if done {
t.Errorf("finshed early on %dth time", i)
return
}
err = vm.CheckErrorCondition(false)
if err != txscript.ErrStackScriptUnfinished {
t.Errorf("got unexepected error %v on %dth iteration",
err, i)
return
}
}
done, err := vm.Step()
if err != nil {
t.Errorf("final step failed %v", err)
return
}
if !done {
t.Errorf("final step isn't done!")
return
}
err = vm.CheckErrorCondition(false)
if err != nil {
t.Errorf("unexpected error %v on final check", err)
}
}
// TestBadPC sets the pc to a deliberately bad result then confirms that Step()
// and Disasm fail correctly.
func TestBadPC(t *testing.T) {
t.Parallel()
type pcTest struct {
script, off int
}
pcTests := []pcTest{
{
script: 2,
off: 0,
},
{
script: 0,
off: 2,
},
}
// tx with almost empty scripts.
tx := &wire.MsgTx{
Version: 1,
TxIn: []*wire.TxIn{
{
PreviousOutPoint: wire.OutPoint{
Hash: wire.ShaHash([32]byte{
0xc9, 0x97, 0xa5, 0xe5,
0x6e, 0x10, 0x41, 0x02,
0xfa, 0x20, 0x9c, 0x6a,
0x85, 0x2d, 0xd9, 0x06,
0x60, 0xa2, 0x0b, 0x2d,
0x9c, 0x35, 0x24, 0x23,
0xed, 0xce, 0x25, 0x85,
0x7f, 0xcd, 0x37, 0x04,
}),
Index: 0,
},
SignatureScript: []uint8{txscript.OP_NOP},
Sequence: 4294967295,
},
},
TxOut: []*wire.TxOut{
{
Value: 1000000000,
PkScript: nil,
},
},
LockTime: 0,
}
pkScript := []byte{txscript.OP_NOP}
for _, test := range pcTests {
vm, err := txscript.NewEngine(pkScript, tx, 0, 0, nil)
if err != nil {
t.Errorf("Failed to create script: %v", err)
}
// set to after all scripts
vm.TstSetPC(test.script, test.off)
_, err = vm.Step()
if err == nil {
t.Errorf("Step with invalid pc (%v) succeeds!", test)
continue
}
_, err = vm.DisasmPC()
if err == nil {
t.Errorf("DisasmPC with invalid pc (%v) succeeds!",
test)
}
}
}
// Test the sigscript generation for valid and invalid inputs, all
// hashTypes, and with and without compression. This test creates
// sigscripts to spend fake coinbase inputs, as sigscripts cannot be
// created for the MsgTxs in txTests, since they come from the blockchain
// and we don't have the private keys.
func TestSignatureScript(t *testing.T) {
t.Parallel()
privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), privKeyD)
nexttest:
for i := range sigScriptTests {
tx := wire.NewMsgTx()
output := wire.NewTxOut(500, []byte{txscript.OP_RETURN})
tx.AddTxOut(output)
for _ = range sigScriptTests[i].inputs {
txin := wire.NewTxIn(coinbaseOutPoint, nil)
tx.AddTxIn(txin)
}
var script []byte
var err error
for j := range tx.TxIn {
var idx int
if sigScriptTests[i].inputs[j].indexOutOfRange {
t.Errorf("at test %v", sigScriptTests[i].name)
idx = len(sigScriptTests[i].inputs)
} else {
idx = j
}
script, err = txscript.SignatureScript(tx, idx,
sigScriptTests[i].inputs[j].txout.PkScript,
sigScriptTests[i].hashType, privKey,
sigScriptTests[i].compress)
if (err == nil) != sigScriptTests[i].inputs[j].sigscriptGenerates {
if err == nil {
t.Errorf("passed test '%v' incorrectly",
sigScriptTests[i].name)
} else {
t.Errorf("failed test '%v': %v",
sigScriptTests[i].name, err)
}
continue nexttest
}
if !sigScriptTests[i].inputs[j].sigscriptGenerates {
// done with this test
continue nexttest
}
tx.TxIn[j].SignatureScript = script
}
// If testing using a correct sigscript but for an incorrect
// index, use last input script for first input. Requires > 0
// inputs for test.
if sigScriptTests[i].scriptAtWrongIndex {
tx.TxIn[0].SignatureScript = script
sigScriptTests[i].inputs[0].inputValidates = false
}
// Validate tx input scripts
scriptFlags := txscript.ScriptBip16 | txscript.ScriptVerifyDERSignatures
for j := range tx.TxIn {
vm, err := txscript.NewEngine(sigScriptTests[i].
inputs[j].txout.PkScript, tx, j, scriptFlags, nil)
if err != nil {
t.Errorf("cannot create script vm for test %v: %v",
sigScriptTests[i].name, err)
continue nexttest
}
err = vm.Execute()
if (err == nil) != sigScriptTests[i].inputs[j].inputValidates {
if err == nil {
t.Errorf("passed test '%v' validation incorrectly: %v",
sigScriptTests[i].name, err)
} else {
t.Errorf("failed test '%v' validation: %v",
sigScriptTests[i].name, err)
}
continue nexttest
}
}
}
}
// validateHandler consumes items to validate from the internal validate channel
// and returns the result of the validation on the internal result channel. It
// must be run as a goroutine.
func (v *txValidator) validateHandler() {
out:
for {
select {
case txVI := <-v.validateChan:
// Ensure the referenced input transaction is available.
txIn := txVI.txIn
originTxHash := &txIn.PreviousOutPoint.Hash
originTx, exists := v.txStore[*originTxHash]
if !exists || originTx.Err != nil || originTx.Tx == nil {
str := fmt.Sprintf("unable to find input "+
"transaction %v referenced from "+
"transaction %v", originTxHash,
txVI.tx.Sha())
err := ruleError(ErrMissingTx, str)
v.sendResult(err)
break out
}
originMsgTx := originTx.Tx.MsgTx()
// Ensure the output index in the referenced transaction
// is available.
originTxIndex := txIn.PreviousOutPoint.Index
if originTxIndex >= uint32(len(originMsgTx.TxOut)) {
str := fmt.Sprintf("out of bounds "+
"input index %d in transaction %v "+
"referenced from transaction %v",
originTxIndex, originTxHash,
txVI.tx.Sha())
err := ruleError(ErrBadTxInput, str)
v.sendResult(err)
break out
}
// Create a new script engine for the script pair.
sigScript := txIn.SignatureScript
pkScript := originMsgTx.TxOut[originTxIndex].PkScript
vm, err := txscript.NewEngine(pkScript, txVI.tx.MsgTx(),
txVI.txInIndex, v.flags, v.sigCache)
if err != nil {
str := fmt.Sprintf("failed to parse input "+
"%s:%d which references output %s:%d - "+
"%v (input script bytes %x, prev output "+
"script bytes %x)", txVI.tx.Sha(),
txVI.txInIndex, originTxHash,
originTxIndex, err, sigScript, pkScript)
err := ruleError(ErrScriptMalformed, str)
v.sendResult(err)
break out
}
// Execute the script pair.
if err := vm.Execute(); err != nil {
str := fmt.Sprintf("failed to validate input "+
"%s:%d which references output %s:%d - "+
"%v (input script bytes %x, prev output "+
"script bytes %x)", txVI.tx.Sha(),
txVI.txInIndex, originTxHash,
originTxIndex, err, sigScript, pkScript)
err := ruleError(ErrScriptValidation, str)
v.sendResult(err)
break out
}
// Validation succeeded.
v.sendResult(nil)
case <-v.quitChan:
break out
}
}
}