From eb6eac67b07d7faf73a180bd23230eb09127962a Mon Sep 17 00:00:00 2001
From: Daniel Cousens <github@dcousens.com>
Date: Tue, 26 Sep 2017 18:43:08 +1000
Subject: [PATCH] txbuilder: fix canSign returning true for missing witness
 value

---
 src/transaction_builder.js | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/transaction_builder.js b/src/transaction_builder.js
index e6adfd1..94d3037 100644
--- a/src/transaction_builder.js
+++ b/src/transaction_builder.js
@@ -663,7 +663,10 @@ function canSign (input) {
     input.signatures !== undefined &&
     input.signatures.length === input.pubKeys.length &&
     input.pubKeys.length > 0 &&
-    input.witness !== undefined
+    (
+      input.witness === false ||
+      (input.witness === true && input.value !== undefined)
+    )
 }
 
 TransactionBuilder.prototype.sign = function (vin, keyPair, redeemScript, hashType, witnessValue, witnessScript) {