[Validation] Reject txes if double spending nullifier in mempool

random-zebra · random-zebra · commit 266134ab9220 · 2020-11-11T14:38:20.000+01:00
diff --git a/src/validation.cpp b/src/validation.cpp
@@ -339,7 +339,7 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const C
     if (!IsStandardTx(tx, nextBlockHeight, reason))
         return state.DoS(0, false, REJECT_NONSTANDARD, reason);
     // is it already in the memory pool?
-    uint256 hash = tx.GetHash();
+    const uint256& hash = tx.GetHash();
     if (pool.exists(hash)) {
         return state.Invalid(false, REJECT_ALREADY_KNOWN, "txn-already-in-mempool");
     }
@@ -358,7 +358,13 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const C
         }
     }
 
-    // TODO check sapling nullifiers
+    // Check sapling nullifiers
+    if (tx.IsShieldedTx()) {
+        for (const auto& sd : tx.sapData->vShieldedSpend) {
+            if (pool.nullifierExists(sd.nullifier))
+                return state.Invalid(false, REJECT_INVALID, "bad-txns-nullifier-double-spent");
+        }
+    }
 
     {
         CCoinsView dummy;

Original file line number	Diff line number	Diff line change
`@@ -339,7 +339,7 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const C`
`339`	`339`	`if (!IsStandardTx(tx, nextBlockHeight, reason))`
`340`	`340`	`return state.DoS(0, false, REJECT_NONSTANDARD, reason);`
`341`	`341`	`// is it already in the memory pool?`
`342`		`- uint256 hash = tx.GetHash();`
	`342`	`+ const uint256& hash = tx.GetHash();`
`343`	`343`	`if (pool.exists(hash)) {`
`344`	`344`	`return state.Invalid(false, REJECT_ALREADY_KNOWN, "txn-already-in-mempool");`
`345`	`345`	`}`
`@@ -358,7 +358,13 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const C`
`358`	`358`	`}`
`359`	`359`	`}`
`360`	`360`
`361`		`- // TODO check sapling nullifiers`
	`361`	`+ // Check sapling nullifiers`
	`362`	`+ if (tx.IsShieldedTx()) {`
	`363`	`+ for (const auto& sd : tx.sapData->vShieldedSpend) {`
	`364`	`+ if (pool.nullifierExists(sd.nullifier))`
	`365`	`+ return state.Invalid(false, REJECT_INVALID, "bad-txns-nullifier-double-spent");`
	`366`	`+ }`
	`367`	`+ }`
`362`	`368`
`363`	`369`	`{`
`364`	`370`	`CCoinsView dummy;`