From 0e69844e8c9c06ddfa44b7923cc7af981352e6be Mon Sep 17 00:00:00 2001
From: alex v <alex@encrypt-s.com>
Date: Sat, 20 Feb 2021 21:05:54 +0100
Subject: [PATCH] Prevent adding duplicated inputs from candidates (#798)

---
 src/blsct/aggregationsession.cpp | 11 +++++++++++
 src/primitives/transaction.h     |  5 +++++
 2 files changed, 16 insertions(+)

diff --git a/src/blsct/aggregationsession.cpp b/src/blsct/aggregationsession.cpp
index 4395c4c20..34100bac6 100644
--- a/src/blsct/aggregationsession.cpp
+++ b/src/blsct/aggregationsession.cpp
@@ -179,6 +179,8 @@ bool AggregationSession::SelectCandidates(CandidateTransaction &ret)
     unsigned int i = 0;
     unsigned int nSelected = 0;
 
+    std::set<uint256> setSeen;
+
     while (nSelected < nSelect && i < vTransactionCandidates.size())
     {
         if (!inputs->HaveInputs(vTransactionCandidates[i].tx))
@@ -203,6 +205,15 @@ bool AggregationSession::SelectCandidates(CandidateTransaction &ret)
         {
             COutPoint prevOut = vTransactionCandidates[i].tx.vin[j].prevout;
 
+            if (setSeen.count(prevOut.GetHash()))
+            {
+                i++;
+                fShouldIContinue = true;
+                break;
+            }
+
+            setSeen.insert(prevOut.GetHash());
+
             if (pwalletMain->mapWallet.count(prevOut.hash))
             {
                 auto prevTx = pwalletMain->mapWallet[prevOut.hash];
diff --git a/src/primitives/transaction.h b/src/primitives/transaction.h
index 4366cec72..13a9f6db3 100644
--- a/src/primitives/transaction.h
+++ b/src/primitives/transaction.h
@@ -62,6 +62,11 @@ class COutPoint
         return !(a == b);
     }
 
+    uint256 GetHash() const
+    {
+        return SerializeHash(*this, SER_GETHASH, SERIALIZE_TRANSACTION_NO_WITNESS);
+    }
+
     std::string ToString() const;
 };