From c4c3dd9cb17e8745e78d9f8711219731ddeb3aeb Mon Sep 17 00:00:00 2001
From: J0J0XMR <163790330+J0J0XMR@users.noreply.github.com>
Date: Mon, 9 Dec 2024 08:44:00 -0600
Subject: [PATCH] mrtnetwork: fix empty segwit deserialization

https://github.com/mrtnetwork/bitcoin_base/commit/7929af9c44e66e9542aa48915eb08014b8390aae
---
 lib/src/bitcoin/script/transaction.dart | 37 ++++++++++++++-----------
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/lib/src/bitcoin/script/transaction.dart b/lib/src/bitcoin/script/transaction.dart
index 4e53e71..6759624 100644
--- a/lib/src/bitcoin/script/transaction.dart
+++ b/lib/src/bitcoin/script/transaction.dart
@@ -95,7 +95,7 @@ class BtcTransaction {
       }
       cursor += 2;
     }
-    final vi = IntUtils.decodeVarint(rawtx.sublist(cursor, cursor + 9));
+    final vi = IntUtils.decodeVarint(rawtx.sublist(cursor));
     cursor += vi.item2;
 
     bool canReplaceByFee = false;
@@ -114,7 +114,7 @@ class BtcTransaction {
     }
 
     List<TxOutput> outputs = [];
-    final viOut = IntUtils.decodeVarint(rawtx.sublist(cursor, cursor + 9));
+    final viOut = IntUtils.decodeVarint(rawtx.sublist(cursor));
     cursor += viOut.item2;
     for (int index = 0; index < viOut.item1; index++) {
       final inp = TxOutput.fromRaw(raw: raw, hasSegwit: hasSegwit, cursor: cursor);
@@ -123,24 +123,25 @@ class BtcTransaction {
     }
     List<TxWitnessInput> witnesses = [];
     if (hasSegwit) {
-      for (int n = 0; n < inputs.length; n++) {
-        final input = inputs[n];
-        if (input.scriptSig.script.isNotEmpty) continue;
-
-        final wVi = IntUtils.decodeVarint(rawtx.sublist(cursor, cursor + 9));
-        cursor += wVi.item2;
-        List<String> witnessesTmp = [];
-        for (int n = 0; n < wVi.item1; n++) {
-          List<int> witness = <int>[];
-          final wtVi = IntUtils.decodeVarint(rawtx.sublist(cursor, cursor + 9));
-          if (wtVi.item1 != 0) {
-            witness = rawtx.sublist(cursor + wtVi.item2, cursor + wtVi.item1 + wtVi.item2);
-          }
+      if (cursor + 4 < rawtx.length) {
+        // in this case the tx contains wintness data.
+        for (int n = 0; n < inputs.length; n++) {
+          final wVi = IntUtils.decodeVarint(rawtx.sublist(cursor));
+          cursor += wVi.item2;
+          List<String> witnessesTmp = [];
+          for (int n = 0; n < wVi.item1; n++) {
+            List<int> witness = <int>[];
+            final wtVi = IntUtils.decodeVarint(rawtx.sublist(cursor));
+            if (wtVi.item1 != 0) {
+              witness = rawtx.sublist(
+                  cursor + wtVi.item2, cursor + wtVi.item1 + wtVi.item2);
+            }
           cursor += wtVi.item1 + wtVi.item2;
           witnessesTmp.add(BytesUtils.toHexString(witness));
         }
 
         witnesses.add(TxWitnessInput(stack: witnessesTmp));
+        }
       }
     }
     List<int>? mwebBytes;
@@ -148,7 +149,11 @@ class BtcTransaction {
       mwebBytes = rawtx.sublist(cursor, rawtx.length - 4);
     }
     cursor = rawtx.length - 4;
-    List<int> lock = rawtx.sublist(cursor, cursor + 4);
+    List<int>? lock;
+    if ((rawtx.length - cursor) >= 4) {
+      lock = rawtx.sublist(cursor, cursor + 4);
+    }
+    print("lock $lock");
     return BtcTransaction(
       inputs: inputs,
       outputs: outputs,