feat(network): Self-healing NAT state by githubawn · Pull Request #3010 · TheSuperHackers/GeneralsGameCode

githubawn · 2026-07-23T22:06:47Z

What this code did:

The ButtonFirewallRefresh button in OptionsMenu.cpp and FirewallNeedToRefresh in FirewallHelper.cpp / OptionPreferences.cpp:

Saved/read FirewallNeedToRefresh and LastFirewallIP boolean flags to/from Options.ini.
Required players to manually click a "Refresh NAT" button in the Options GUI when changing network interfaces or encountering P2P negotiation failures.
Contaminated GlobalData (TheWritableGlobalData->m_firewallBehavior) with disk-persisted firewall state across process restarts.

How the new code works:

Automated In-Engine RAM Lifecycle: NAT state classification (m_behavior) is managed 100% in memory within FirewallHelperClass.
Transparent Background Probing: Non-blocking STUN probing runs in the background during online lobby entry (WOLWelcomeMenu), caching the classified result in RAM for the remainder of the game session.
Self-Healing Re-Detection: If a peer connection times out (NAT.cpp) or the user selects a new IP address in Options (OptionPreferences.cpp), TheFirewallHelper->flagNeedToRefresh(TRUE) resets m_behavior = FIREWALL_TYPE_UNKNOWN in RAM to seamlessly trigger a fresh background probe.
Clean GUI Deprecation: Hides OptionsMenu.wnd:ButtonFirewallRefresh via winHide(TRUE) in C++ without breaking custom or legacy .wnd layout files.

Background & Reason for Removal:

Obsolete Manual Workaround: Manual NAT refresh buttons are a legacy 2003 workaround; modern network stacks handle NAT re-detection automatically in-engine.
Elimination of Disk I/O: Completely removes FirewallNeedToRefresh and LastFirewallIP from Options.ini, preventing stale or corrupted flags from persisting across game crashes or process restarts.
Architectural Decoupling: Fully encapsulates STUN probing state inside FirewallHelperClass in memory, removing direct mutations to TheWritableGlobalData->m_firewallBehavior.

greptile-apps · 2026-07-23T22:09:34Z

Greptile Summary

This PR replaces persisted firewall state with a session-owned background NAT detector and updates multiplayer setup to consume its in-memory classification.

Confidence Score: 4/5

The PR is not yet safe to merge because peers can retain an UNKNOWN NAT classification even after the local attach-time refresh obtains the completed result.

The local traversal fallback does not update or redistribute NAT behavior that was published before detection completed, so remote peers can select the wrong port strategy and fail connection establishment.

Files Needing Attention: Core/GameEngine/Source/GameNetwork/NAT.cpp and the staging/quick-match NAT publication paths

Important Files Changed

Filename	Overview
Core/GameEngine/Source/GameNetwork/FirewallHelper.cpp	Moves firewall classification and restart state into the helper and fully resets active probe resources before redetection.
Core/GameEngine/Source/GameNetwork/NAT.cpp	Restarts detection after negotiation failures and refreshes local traversal behavior, but the refresh does not correct NAT state already distributed to peers.
Generals/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/WOLGameSetupMenu.cpp	Publishes the helper's best-known NAT behavior when entering a staging room.
Generals/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/WOLQuickMatchMenu.cpp	Supplies the helper's best-known NAT behavior to quick matchmaking.
GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/WOLGameSetupMenu.cpp	Mirrors the Generals staging-room NAT publication changes for Zero Hour.
GeneralsMD/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/WOLQuickMatchMenu.cpp	Mirrors the Generals quick-match NAT publication changes for Zero Hour.

Sequence Diagram

sequenceDiagram
    participant Probe as FirewallHelper
    participant Lobby as GameSpy Lobby
    participant Peer as Remote Peer
    participant NAT as NAT Traversal
    Probe->>Probe: Start background detection
    Lobby->>Probe: Request best-known behavior
    Probe-->>Lobby: Classification or UNKNOWN
    Lobby->>Peer: Distribute slot NAT values
    NAT->>Probe: Refresh local behavior at traversal
    NAT->>NAT: Use completed local classification
    Peer->>Peer: Retain distributed slot classification

Prompt To Fix All With AI

### Issue 1
Core/GameEngine/Source/GameNetwork/NAT.cpp:600-610
**Remote peers retain UNKNOWN NAT**

When a player enters staging or quick match before firewall detection completes, the lobby distributes UNKNOWN as that player's NAT behavior. This fallback refreshes only the local traversal logic and does not update the slot state already distributed to remote peers, causing them to use the raw source port and time out behind a port-mangling NAT.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (12): Last reviewed commit: "review feedback" | Re-trigger Greptile}

### What this code did: The `ButtonFirewallRefresh` button in `OptionsMenu.cpp` and `FirewallNeedToRefresh` in `FirewallHelper.cpp` / `OptionPreferences.cpp`: 1. Saved/read `FirewallNeedToRefresh` and `LastFirewallIP` boolean flags to/from `Options.ini`. 2. Required players to manually click a "Refresh NAT" button in the Options GUI when changing network interfaces or encountering P2P negotiation failures. 3. Contaminated `GlobalData` (`TheWritableGlobalData->m_firewallBehavior`) with disk-persisted firewall state across process restarts. ### How the new code works: 1. **Automated In-Engine RAM Lifecycle**: NAT state classification (`m_behavior`) is managed 100% in memory within `FirewallHelperClass`. 2. **Transparent Background Probing**: Non-blocking STUN probing runs in the background during online lobby entry (`WOLWelcomeMenu`), caching the classified result in RAM for the remainder of the game session. 3. **Self-Healing Re-Detection**: If a peer connection times out (`NAT.cpp`) or the user selects a new IP address in Options (`OptionPreferences.cpp`), `TheFirewallHelper->flagNeedToRefresh(TRUE)` resets `m_behavior = FIREWALL_TYPE_UNKNOWN` in RAM to seamlessly trigger a fresh background probe. 4. **Clean GUI Deprecation**: Hides `OptionsMenu.wnd:ButtonFirewallRefresh` via `winHide(TRUE)` in C++ without breaking custom or legacy `.wnd` layout files. ### Background & Reason for Removal: - **Obsolete Manual Workaround**: Manual NAT refresh buttons are a legacy 2003 workaround; modern network stacks handle NAT re-detection automatically in-engine. - **Elimination of Disk I/O**: Completely removes `FirewallNeedToRefresh` and `LastFirewallIP` from `Options.ini`, preventing stale or corrupted flags from persisting across game crashes or process restarts. - **Architectural Decoupling**: Fully encapsulates STUN probing state inside `FirewallHelperClass` in memory, removing direct mutations to `TheWritableGlobalData->m_firewallBehavior`.

…e-detection

…d matchmaking

placed nat detection earlier in the online Code some more cleanup

xezon

How can this change be tested? Did you test it? Does it work?

xezon · 2026-07-26T08:00:33Z

 	checkSendDelay				 = TheWindowManager->winGetWindowFromId( nullptr, checkSendDelayID);
-	buttonFirewallRefreshID	= TheNameKeyGenerator->nameToKey( "OptionsMenu.wnd:ButtonFirewallRefresh" );
-	buttonFirewallRefresh		= TheWindowManager->winGetWindowFromId( nullptr, buttonFirewallRefreshID);
+	// TheSuperHackers @info 25/07/2026 Refresh button has been hidden, we have migrated this to self-healing


Please avoid using "we", "i". Ideally comments are person-less.

xezon · 2026-07-26T08:03:00Z


+	if (TheFirewallHelper != nullptr)
+	{
+		TheFirewallHelper->behaviorDetectionUpdate();


Why does the WOL Login need a firewall helper update? Isn't the firewall helper needed for peer to peer connections?

This is to move the firewall NAT detection as early as possible to heighten the chance it is known once you join a match.

xezon · 2026-07-26T08:09:56Z

+	(*this)[key] = IP;
+
+	if (TheFirewallHelper != nullptr)
+		TheFirewallHelper->flagNeedToRefresh(TRUE);


It looks like this class is not intended to set state elsewhere in the program. Can this be implemented differently to keep the focus of this class for writing options?

xezon · 2026-07-26T08:13:26Z


+		Bool isBehaviorDetectionComplete() {return(m_currentState == DETECTIONSTATE_DONE);}
+		FirewallBehaviorType getLastFirewallBehavior() {return(m_lastBehavior);}
+		Short getLastSourcePortAllocationDelta() {return((Short)m_lastSourcePortAllocationDelta);}


Can all be const

xezon · 2026-07-26T08:16:17Z


 	TheGameSpyConfig = GameSpyConfigInterface::create(configBuffer);

+	if (TheFirewallHelper == nullptr)


Can this condition ever be false at this point? If not, can it be replaced with an assert?

xezon · 2026-07-26T08:20:22Z

+	return helper;
+}
+
+FirewallHelperClass::FirewallBehaviorType getBestKnownFirewallBehavior()


All it does is interact with FirewallHelperClass. Can this be member of FirewallHelperClass?

xezon · 2026-07-26T08:20:35Z

+	return FirewallHelperClass::FIREWALL_TYPE_UNKNOWN;
+}
+
+Short getBestKnownSourcePortAllocationDelta()


All it does is interact with FirewallHelperClass. Can this be member of FirewallHelperClass?

xezon · 2026-07-26T08:25:58Z

-	m_lastBehavior = (FirewallBehaviorType) ConfigINI.Get_Int("MultiPlayer", "FirewallSettings", FIREWALL_UNKNOWN);
-	m_lastSourcePortAllocationDelta = ConfigINI.Get_Int("MultiPlayer", "FirewallDelta", 1);
-#endif //(0)
+	if (flag) {


This flag argument looks very useless. Can be removed. "Munkee" text above needs updating then.

githubawn · 2026-07-29T15:00:00Z

How can this change be tested? Did you test it? Does it work?

Tested this with a Gamespy emulator and it does follow the intended changes.
GO might want to validate this one manually. I have no clue in how many ways this can break.

githubawn · 2026-07-29T22:58:12Z

@greptile

greptile-apps · 2026-07-29T23:00:33Z

+FirewallHelperClass::FirewallBehaviorType NAT::getLocalNATBehavior() {
+	FirewallHelperClass::FirewallBehaviorType published =
+		m_slotList[m_connectionNodes[m_localNodeNumber].m_slotIndex]->getNATBehavior();
+
+	FirewallHelperClass::FirewallBehaviorType detected = FirewallHelperClass::getBestKnownFirewallBehavior();
+	if (detected != FirewallHelperClass::FIREWALL_TYPE_UNKNOWN) {
+		return detected;
+	}
+
+	return published;
+}


Remote peers retain UNKNOWN NAT

When a player enters staging or quick match before firewall detection completes, the lobby distributes UNKNOWN as that player's NAT behavior. This fallback refreshes only the local traversal logic and does not update the slot state already distributed to remote peers, causing them to use the raw source port and time out behind a port-mangling NAT.

Knowledge Base Used: GameNetwork: Multiplayer Networking

Prompt To Fix With AI

This is a comment left during a code review. Path: Core/GameEngine/Source/GameNetwork/NAT.cpp Line: 600-610 Comment: **Remote peers retain UNKNOWN NAT** When a player enters staging or quick match before firewall detection completes, the lobby distributes UNKNOWN as that player's NAT behavior. This fallback refreshes only the local traversal logic and does not update the slot state already distributed to remote peers, causing them to use the raw source port and time out behind a port-mangling NAT. **Knowledge Base Used:** [GameNetwork: Multiplayer Networking](https://app.greptile.com/thesuperhackers/-/custom-context/knowledge-base/thesuperhackers/generalsgamecode/-/docs/gamenetwork-multiplayer.md) --- For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

githubawn changed the title ~~feat(network): make NAT state self-healing~~ feat(network): Self-healing NAT state Jul 23, 2026

greptile-apps Bot reviewed Jul 23, 2026

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Comment thread Core/GameEngine/Source/GameNetwork/FirewallHelper.cpp Outdated

githubawn force-pushed the refactor/remove-refresh-nat branch from c5806f1 to 79e5c8e Compare July 23, 2026 22:14

githubawn force-pushed the refactor/remove-refresh-nat branch from 79e5c8e to 8113c09 Compare July 23, 2026 22:18

greptile-apps Bot reviewed Jul 23, 2026

View reviewed changes

Comment thread Core/GameEngine/Source/GameNetwork/FirewallHelper.cpp Outdated

githubawn added 2 commits July 24, 2026 00:25

fix(network): Reset probe state and close spare sockets on firewall r…

0a4ada6

…e-detection

fix(network): Preserve FirewallHelper lifetime across online menus an…

fd146ae

…d matchmaking

Skyaero42 reviewed Jul 25, 2026

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Updated after review feedback

6c50745

greptile-apps Bot reviewed Jul 25, 2026

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Comment thread Generals/Code/GameEngine/Source/GameClient/GUI/GUICallbacks/Menus/WOLGameSetupMenu.cpp Outdated

update after greptile feedback

67eef47

placed nat detection earlier in the online Code some more cleanup

greptile-apps Bot reviewed Jul 25, 2026

View reviewed changes

Comment thread Core/GameEngine/Source/GameNetwork/FirewallHelper.cpp

xezon reviewed Jul 26, 2026

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xezon added Enhancement Is new feature or request Minor Severity: Minor < Major < Critical < Blocker Network Anything related to network, servers Gen Relates to Generals ZH Relates to Zero Hour labels Jul 26, 2026

refactor(network): Put Refresh NAT button hiding behind ENABLE_GUI_HACKS

802dd30

greptile-apps Bot reviewed Jul 26, 2026

View reviewed changes

Comment thread Core/GameEngine/Source/GameNetwork/FirewallHelper.cpp Outdated

githubawn marked this pull request as draft July 26, 2026 17:08

Implemented feedback and narrowed timeouts

b0f1841

greptile-apps Bot reviewed Jul 29, 2026

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Comment thread Core/GameEngine/Source/GameNetwork/FirewallHelper.cpp Outdated

greptile feedback

a55ec50

greptile-apps Bot reviewed Jul 29, 2026

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Comment thread Core/GameEngine/Source/Common/OptionPreferences.cpp

greptile-apps Bot reviewed Jul 29, 2026

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Comment thread Core/GameEngine/Source/GameNetwork/FirewallHelper.cpp

review feedback

4d04387

greptile-apps Bot reviewed Jul 29, 2026

View reviewed changes


		TheGameSpyConfig = GameSpyConfigInterface::create(configBuffer);

		if (TheFirewallHelper == nullptr)

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githubawn commented Jul 23, 2026

What this code did:

How the new code works:

Background & Reason for Removal:

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greptile-apps Bot commented Jul 23, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Greptile Summary

Confidence Score: 4/5

Important Files Changed

Sequence Diagram

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xezon Jul 26, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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githubawn commented Jul 29, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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githubawn commented Jul 29, 2026

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greptile-apps Bot commented Jul 23, 2026 •

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xezon Jul 26, 2026 •

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githubawn commented Jul 29, 2026 •

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