Merge pull request 'Reject ztxs with duplicate zkproofs' (#327) from duplicate_proofs into dev

Reviewed-on: #327

src/consensus/validation.h

@@ -29,6 +29,8 @@ static const unsigned char REJECT_MALFORMED = 0x01;
 static const unsigned char REJECT_INVALID = 0x10;
 static const unsigned char REJECT_OBSOLETE = 0x11;
 static const unsigned char REJECT_DUPLICATE = 0x12;
+static const unsigned char REJECT_DUPLICATE_OUTPUT_PROOF = 0x13;
+static const unsigned char REJECT_DUPLICATE_SPEND_PROOF  = 0x14;
 static const unsigned char REJECT_NONSTANDARD = 0x40;
 static const unsigned char REJECT_DUST = 0x41;
 static const unsigned char REJECT_INSUFFICIENTFEE = 0x42;

src/main.cpp

@@ -1751,7 +1751,31 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
     {
         return error("AcceptToMemoryPool: CheckTransaction failed");
     }
-    
+
+    // Reject duplicate output proofs in a single ztx in mempool
+    // Migrate this to CheckTransaction() to make it a consensus requirement
+    {
+        set<libzcash::GrothProof> vSaplingOutputProof;
+        BOOST_FOREACH(const OutputDescription& output, tx.vShieldedOutput)
+        {
+            if (vSaplingOutputProof.count(output.zkproof))
+                return state.Invalid(error("AcceptToMemoryPool: duplicate output proof"),REJECT_DUPLICATE_OUTPUT_PROOF, "bad-txns-duplicate-output-proof");
+            vSaplingOutputProof.insert(output.zkproof);
+        }
+    }
+
+    // Reject duplicate spend proofs in a single ztx in mempool
+    // Migrate this to CheckTransaction() to make it a consensus requirement
+    {
+        set<libzcash::GrothProof> vSaplingSpendProof;
+        BOOST_FOREACH(const SpendDescription& spend, tx.vShieldedSpend)
+        {
+            if (vSaplingSpendProof.count(spend.zkproof))
+                return state.Invalid(error("AcceptToMemoryPool: duplicate spend proof"),REJECT_DUPLICATE_SPEND_PROOF, "bad-txns-duplicate-spend-proof");
+            vSaplingSpendProof.insert(spend.zkproof);
+        }
+    }
+
     // DoS level set to 10 to be more forgiving.
     // Check transaction contextually against the set of consensus rules which apply in the next block to be mined.
     if (!ContextualCheckTransaction(0,0,0,tx, state, nextBlockHeight, (dosLevel == -1) ? 10 : dosLevel))