Merge bitcoin#7642: Avoid "Unknown command" messages when receiving getaddr on outbound c…

9988554 No "Unknown command" for getaddr command. (R E Broadley)

Author: sipa

src/main.cpp

@@ -5064,13 +5064,18 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
     }
 
 
-    // This asymmetric behavior for inbound and outbound connections was introduced
-    // to prevent a fingerprinting attack: an attacker can send specific fake addresses
-    // to users' AddrMan and later request them by sending getaddr messages.
-    // Making nodes which are behind NAT and can only make outgoing connections ignore
-    // the getaddr message mitigates the attack.
-    else if ((strCommand == NetMsgType::GETADDR) && (pfrom->fInbound))
+    else if (strCommand == NetMsgType::GETADDR)
     {
+        // This asymmetric behavior for inbound and outbound connections was introduced
+        // to prevent a fingerprinting attack: an attacker can send specific fake addresses
+        // to users' AddrMan and later request them by sending getaddr messages.
+        // Making nodes which are behind NAT and can only make outgoing connections ignore
+        // the getaddr message mitigates the attack.
+        if (!pfrom->fInbound) {
+            LogPrint("net", "Ignoring \"getaddr\" from outbound connection. peer=%d\n", pfrom->id);
+            return true;
+        }
+
         pfrom->vAddrToSend.clear();
         vector<CAddress> vAddr = addrman.GetAddr();
         BOOST_FOREACH(const CAddress &addr, vAddr)