Change in transaction pull scheduling to prevent InvBlock-related attacks

Co-authored-by: Suhas Daftuar <sdaftuar@gmail.com>

src/net.h

@@ -67,10 +67,6 @@ static const bool DEFAULT_UPNP = USE_UPNP;
 #else
 static const bool DEFAULT_UPNP = false;
 #endif
-/** The maximum number of entries in mapAskFor */
-static const size_t MAPASKFOR_MAX_SZ = MAX_INV_SZ;
-/** The maximum number of entries in setAskFor (larger due to getdata latency)*/
-static const size_t SETASKFOR_MAX_SZ = 2 * MAX_INV_SZ;
 /** The maximum number of peer connections to maintain. */
 static const unsigned int DEFAULT_MAX_PEER_CONNECTIONS = 125;
 /** The default for -maxuploadtarget. 0 = Unlimited */
@@ -514,8 +510,6 @@ extern bool fDiscover;
 extern bool fListen;
 extern bool fRelayTxes;
 
-extern limitedmap<uint256, int64_t> mapAlreadyAskedFor;
-
 /** Subversion as sent to the P2P network in `version` messages */
 extern std::string strSubVersion;
 
@@ -704,8 +698,6 @@ public:
     // and in the order requested.
     std::vector<uint256> vInventoryBlockToSend GUARDED_BY(cs_inventory);
     CCriticalSection cs_inventory;
-    std::set<uint256> setAskFor;
-    std::multimap<int64_t, CInv> mapAskFor;
     int64_t nNextInvSend{0};
     // Used for headers announcements - unfiltered blocks to relay
     std::vector<uint256> vBlockHashesToAnnounce GUARDED_BY(cs_inventory);
@@ -852,8 +844,6 @@ public:
         vBlockHashesToAnnounce.push_back(hash);
     }
 
-    void AskFor(const CInv& inv);
-
     void CloseSocketDisconnect();
 
     void copyStats(CNodeStats &stats);