From 3cc4ac137669c3ee4a6d602c533d16baedd83aa5 Mon Sep 17 00:00:00 2001
From: UdjinM6 <UdjinM6@users.noreply.github.com>
Date: Wed, 19 Sep 2018 15:04:35 +0300
Subject: [PATCH] Fix crash bug with duplicate inputs within a transaction
 (#2302)

* Fix crash bug with duplicate inputs within a transaction

Introduced by #9049

* Remove redundant parameter fCheckDuplicateInputs from CheckTransaction
---
 src/validation.cpp | 18 ++++++++----------
 src/validation.h   |  2 +-
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/src/validation.cpp b/src/validation.cpp
index 47bb76760..3b067eea9 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -513,7 +513,7 @@ int GetUTXOConfirmations(const COutPoint& outpoint)
 }
 
 
-bool CheckTransaction(const CTransaction& tx, CValidationState &state, bool fCheckDuplicateInputs)
+bool CheckTransaction(const CTransaction& tx, CValidationState &state)
 {
     // Basic checks that don't depend on any context
     if (tx.vin.empty())
@@ -539,14 +539,12 @@ bool CheckTransaction(const CTransaction& tx, CValidationState &state, bool fChe
             return state.DoS(100, false, REJECT_INVALID, "bad-txns-txouttotal-toolarge");
     }
 
-    // Check for duplicate inputs - note that this check is slow so we skip it in CheckBlock
-    if (fCheckDuplicateInputs) {
-        std::set<COutPoint> vInOutPoints;
-        for (const auto& txin : tx.vin)
-        {
-            if (!vInOutPoints.insert(txin.prevout).second)
-                return state.DoS(100, false, REJECT_INVALID, "bad-txns-inputs-duplicate");
-        }
+    // Check for duplicate inputs
+    std::set<COutPoint> vInOutPoints;
+    for (const auto& txin : tx.vin)
+    {
+        if (!vInOutPoints.insert(txin.prevout).second)
+            return state.DoS(100, false, REJECT_INVALID, "bad-txns-inputs-duplicate");
     }
 
     if (tx.IsCoinBase())
@@ -3437,7 +3435,7 @@ bool CheckBlock(const CBlock& block, CValidationState& state, const Consensus::P
 
     // Check transactions
     for (const auto& tx : block.vtx)
-        if (!CheckTransaction(*tx, state, false))
+        if (!CheckTransaction(*tx, state))
             return state.Invalid(false, state.GetRejectCode(), state.GetRejectReason(),
                                  strprintf("Transaction check failed (tx hash %s) %s", tx->GetHash().ToString(), state.GetDebugMessage()));
 
diff --git a/src/validation.h b/src/validation.h
index 91967b4e9..95bcaf595 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -389,7 +389,7 @@ void UpdateCoins(const CTransaction& tx, CCoinsViewCache& inputs, int nHeight);
 /** Transaction validation functions */
 
 /** Context-independent validity checks */
-bool CheckTransaction(const CTransaction& tx, CValidationState& state, bool fCheckDuplicateInputs=true);
+bool CheckTransaction(const CTransaction& tx, CValidationState& state);
 
 namespace Consensus {