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txscript/engine: Check ps2h push before parsing script

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This moves the check for non push-only pay-to-script-hash signature
scripts before the script parsing logic when creating a new engine
instance to avoid the extra overhead in the error case.
This commit is contained in:
Conner Fromknecht 2019-04-19 00:50:54 -07:00 committed by Roy Lee
parent 2674b2926b
commit f1ab6cc7cb
1 changed files with 15 additions and 13 deletions
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28
txscript/engine.go
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@ -918,6 +918,21 @@ func NewEngine(scriptPubKey []byte, tx *wire.MsgTx, txIdx int, flags ScriptFlags
"signature script is not push only")
}
// 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.
// 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 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
@ -943,19 +958,6 @@ func NewEngine(scriptPubKey []byte, tx *wire.MsgTx, txIdx int, flags ScriptFlags
if len(scripts[0]) == 0 {
vm.scriptIdx++
}
if vm.hasFlag(ScriptBip16) && isScriptHashScript(scriptPubKey) {
// Only accept input scripts that push data for P2SH.
// 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
}
if vm.hasFlag(ScriptVerifyMinimalData) {
vm.dstack.verifyMinimalData = true
vm.astack.verifyMinimalData = true