txscript/script.go

@@ -100,11 +100,7 @@ func isWitnessScriptHash(pops []parsedOpcode) bool {
 // 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

txscript/standard.go

@@ -421,6 +421,28 @@ func isWitnessPubKeyHashScript(script []byte) bool {
 	return extractWitnessPubKeyHash(script) != nil
 }
 
+// extractWitnessScriptHash extracts the witness script hash from the passed
+// script if it is standard pay-to-witness-script-hash script. It will return
+// nil otherwise.
+func extractWitnessScriptHash(script []byte) []byte {
+	// A pay-to-witness-script-hash script is of the form:
+	//   OP_0 OP_DATA_32 <32-byte-hash>
+	if len(script) == 34 &&
+		script[0] == OP_0 &&
+		script[1] == OP_DATA_32 {
+
+		return script[2:34]
+	}
+
+	return nil
+}
+
+// isWitnessScriptHashScript returns whether or not the passed script is a
+// standard pay-to-witness-script-hash script.
+func isWitnessScriptHashScript(script []byte) bool {
+	return extractWitnessScriptHash(script) != nil
+}
+
 // isNullData returns true if the passed script is a null data transaction,
 // false otherwise.
 func isNullData(pops []parsedOpcode) bool {