[p2p] don't query orphanage by txid

src/net_processing.cpp

@@ -2295,7 +2295,12 @@ bool PeerManagerImpl::AlreadyHaveTx(const GenTxid& gtxid, bool include_reconside
 
     const uint256& hash = gtxid.GetHash();
 
-    if (m_orphanage.HaveTx(gtxid)) return true;
+    // Always query by wtxid, even if gtxid has a Txid type.
+    // It is possible that the transaction in the orphanage has the same txid but a different
+    // witness (e.g. malleated by an attacker) and we don't want to return false positives.
+    // However, we are interested in finding non-segwit transactions whose txid == wtxid.
+    // So query this txid "casted" to a wtxid.
+    if (m_orphanage.HaveTx(GenTxid::Wtxid(hash))) return true;
 
     if (include_reconsiderable && m_recent_rejects_reconsiderable.contains(hash)) return true;