Bail early in processing transactions in blocks only mode.

Previously unsolicited transactions would be processed as normal.

src/main.cpp

@@ -4384,6 +4384,14 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
 
     else if (strCommand == "tx")
     {
+        // Stop processing the transaction early if
+        // We are in blocks only mode and peer is either not whitelisted or whitelistalwaysrelay is off
+        if (GetBoolArg("-blocksonly", DEFAULT_BLOCKSONLY) && (!pfrom->fWhitelisted || !GetBoolArg("-whitelistalwaysrelay", DEFAULT_WHITELISTALWAYSRELAY)))
+        {
+            LogPrint("net", "peer sent transaction in violation of protocol peer=%d\n", pfrom->id);
+            return true;
+        }
+
         vector<uint256> vWorkQueue;
         vector<uint256> vEraseQueue;
         CTransaction tx;