diff --git a/txscript/sign.go b/txscript/sign.go index b9f8b2dbb4..587910649c 100644 --- a/txscript/sign.go +++ b/txscript/sign.go @@ -212,73 +212,6 @@ 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 @@ -397,6 +330,74 @@ 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. +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. + 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, + // therefore the error is ignored. + 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 + } +} + // 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 {