[refactor] move AlreadyHaveTx to TxDownload

This is move-only.
Also delete external RecentConfirmedTransactionsFilter() access since it
is no longer necessary.

src/node/txdownloadman.h

@@ -11,6 +11,7 @@
 class CBlock;
 class CRollingBloomFilter;
 class CTxMemPool;
+class GenTxid;
 class TxOrphanage;
 class TxRequestTracker;
 namespace node {
@@ -53,12 +54,20 @@ public:
     TxRequestTracker& GetTxRequestRef();
     CRollingBloomFilter& RecentRejectsFilter();
     CRollingBloomFilter& RecentRejectsReconsiderableFilter();
-    CRollingBloomFilter& RecentConfirmedTransactionsFilter();
 
     // Responses to chain events. TxDownloadManager is not an actual client of ValidationInterface, these are called through PeerManager.
     void ActiveTipChange();
     void BlockConnected(const std::shared_ptr<const CBlock>& pblock);
     void BlockDisconnected();
+
+    /** Check whether we already have this gtxid in:
+     *  - mempool
+     *  - orphanage
+     *  - m_recent_rejects
+     *  - m_recent_rejects_reconsiderable (if include_reconsiderable = true)
+     *  - m_recent_confirmed_transactions
+     *  */
+    bool AlreadyHaveTx(const GenTxid& gtxid, bool include_reconsiderable);
 };
 } // namespace node
 #endif // BITCOIN_NODE_TXDOWNLOADMAN_H

src/node/txdownloadman_impl.cpp

@@ -34,10 +34,6 @@ CRollingBloomFilter& TxDownloadManager::RecentRejectsReconsiderableFilter()
 {
     return m_impl->RecentRejectsReconsiderableFilter();
 }
-CRollingBloomFilter& TxDownloadManager::RecentConfirmedTransactionsFilter()
-{
-    return m_impl->RecentConfirmedTransactionsFilter();
-}
 void TxDownloadManager::ActiveTipChange()
 {
     m_impl->ActiveTipChange();
@@ -50,6 +46,10 @@ void TxDownloadManager::BlockDisconnected()
 {
     m_impl->BlockDisconnected();
 }
+bool TxDownloadManager::AlreadyHaveTx(const GenTxid& gtxid, bool include_reconsiderable)
+{
+    return m_impl->AlreadyHaveTx(gtxid, include_reconsiderable);
+}
 
 // TxDownloadManagerImpl
 void TxDownloadManagerImpl::ActiveTipChange()
@@ -84,4 +84,33 @@ void TxDownloadManagerImpl::BlockDisconnected()
     // should be just after a new block containing it is found.
     RecentConfirmedTransactionsFilter().reset();
 }
+
+bool TxDownloadManagerImpl::AlreadyHaveTx(const GenTxid& gtxid, bool include_reconsiderable)
+{
+    const uint256& hash = gtxid.GetHash();
+
+    if (gtxid.IsWtxid()) {
+        // Normal query by wtxid.
+        if (m_orphanage.HaveTx(Wtxid::FromUint256(hash))) return true;
+    } else {
+        // Never query by txid: it is possible that the transaction in the orphanage has the same
+        // txid but a different witness, which would give us a false positive result. If we decided
+        // not to request the transaction based on this result, an attacker could prevent us from
+        // downloading a transaction by intentionally creating a malleated version of it.  While
+        // only one (or none!) of these transactions can ultimately be confirmed, we have no way of
+        // discerning which one that is, so the orphanage can store multiple transactions with the
+        // same txid.
+        //
+        // While we won't query by txid, we can try to "guess" what the wtxid is based on the txid.
+        // A non-segwit transaction's txid == wtxid. Query this txid "casted" to a wtxid. This will
+        // help us find non-segwit transactions, saving bandwidth, and should have no false positives.
+        if (m_orphanage.HaveTx(Wtxid::FromUint256(hash))) return true;
+    }
+
+    if (include_reconsiderable && RecentRejectsReconsiderableFilter().contains(hash)) return true;
+
+    if (RecentConfirmedTransactionsFilter().contains(hash)) return true;
+
+    return RecentRejectsFilter().contains(hash) || m_opts.m_mempool.exists(gtxid);
+}
 } // namespace node

src/node/txdownloadman_impl.h

@@ -9,6 +9,7 @@
 #include <common/bloom.h>
 #include <kernel/chain.h>
 #include <net.h>
+#include <primitives/transaction.h>
 #include <txorphanage.h>
 #include <txrequest.h>
 
@@ -130,6 +131,8 @@ public:
     void ActiveTipChange();
     void BlockConnected(const std::shared_ptr<const CBlock>& pblock);
     void BlockDisconnected();
+
+    bool AlreadyHaveTx(const GenTxid& gtxid, bool include_reconsiderable);
 };
 } // namespace node
 #endif // BITCOIN_NODE_TXDOWNLOADMAN_IMPL_H