Add support for V3 tunnels by 11EJDE11 · Pull Request #845 · CnCNet/xna-cncnet-client

11EJDE11 · 2025-10-11T03:11:38Z

Closes #349

V2 tunnels remain fully supported.
Adds V3 Static tunnels: One host-chosen tunnel shared by all players (similar to V2).
Adds V3 Dynamic tunnels: Each pair of players automatically negotiates the optimal tunnel/P2P between them.

How V3 Tunnels Work

In V2, all players share a single tunnel.
Example:

Player1 (Australia)
Player2 (New Zealand)
Player3 (England)
Tunnel: France

For P1 to send data to P2:
P1 Australia -> Tunnel France -> P2 NZ  = 550ms

In V3 dynamic mode, each pair of players negotiates the best tunnel route:

P1 <--> P2  -> Tunnel: Australia (50ms)
P1 <--> P3  -> Tunnel: France (300ms)
P2 <--> P3  -> Tunnel: Seattle (310ms)
So now for P1 to send data to P2:
P1 Australia > Tunnel Australia > P2 NZ = 50ms (90.9% faster)
And the slowest link is now 310ms instead of 550ms (43.6% faster overall).

The client now acts as an intermediary: the game connects to the client, which then routes packets to the negotiated tunnels. This is for both static and dynamic V3.

Negotiation Process

Negotiations occur automatically when players join a lobby or the tunnel mode changes, and takes a few seconds to run once the player list has arrived.

Phase 1 - Relay Negotiation

Each player pair tests all available V3 relay tunnels.
Which tunnels are tested is controlled by the Ping unofficial CnCNet tunnels option - when off, only official and recommended tunnels are used.
One player in each pair is designated as the decider (lower player ID; ties broken by name ordering).

The non-decider sends Connected packets to every candidate tunnel every 500 ms.
The decider, on receiving a Connected packet through a tunnel, sends 5 PingRequest packets and measures round-trip time.
The non-decider replies with PingResponse packets.

Once 50% of tunnels have been tested, the decider selects the best tunnel (lowest RTT, with a packet-loss penalty) and sends a TunnelChoice packet, which includes the measured ping, packet loss, and the decider's P2P capability.
The non-decider acknowledges with TunnelAck, also advertising whether they have P2P enabled. Relay negotiation is now complete.

Phase 2 - P2P Upgrade Round (optional; requires both players to have P2P enabled)

After a relay tunnel is agreed:

Each player gathers their P2P candidates: all local LAN addresses plus a STUN-discovered public (reflexive) address.
Candidates are exchanged through the agreed relay tunnel via P2PInfo packets.
Both players send Connected packets directly to each other's candidates - unlike relay negotiation, both sides punch simultaneously to open NAT mappings on each end.
The same decider/non-decider ping protocol runs over the direct paths only (4 pings per path, tighter timeouts).
The decider calls SelectBestTunnel() across all paths - relay and direct combined - and sends a new TunnelChoice through whichever wins.
The non-decider adopts whichever tunnel the TunnelChoice arrives on. If no direct path wins or the round times out, both stay on the relay from Phase 1.

…bled by host

Add V3GameTunnelBridge Add V3TunnelCommunicator Add V3TunnelNegotiator Add TunnelFailed event Update supported tunnel versions

Fixup GameCreationWindow control visibility Remove unnecessary tunnel parameter in V3PlayerInfo Add NegotiationStatusPanel Add tunnel negotiations to CnCNetGameLobby Add V3 tunnel support to CnCNetGameLobby

Move to file-scoped namespaces Fix missing texture on status panel Fix issue with decider seeing OK instead of ping results

Fix an issue with automatic tunnel selection Style fixups Split TunnelChosenEventArgs into new file

Remove IDisposable on bridge

Remove unecessary code

Better updating of player ping indicators

github-actions · 2025-10-11T03:15:42Z

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CnCRAZER · 2025-10-30T03:22:53Z

Perhaps the ability to add a button within one of the clients ini files to toggle between V2 and V3 would be useful. Just a thought

Fix V2 tunnels not matching

Copilot

Pull request overview

Copilot reviewed 41 out of 43 changed files in this pull request and generated 2 comments.

+                        int received = udpClient.Client.ReceiveFrom(receiveBuffer, ref remoteEndpoint);
+                        var receivedTime = Stopwatch.GetTimestamp();
+
+                        if (_endpointToTunnel.TryGetValue((IPEndPoint)remoteEndpoint, out var tunnel))
+                            ProcessReceivedPacket(receiveBuffer.AsMemory(0, received), receivedTime, tunnel);
+                        else if (_pendingStunQueries.TryRemove((IPEndPoint)remoteEndpoint, out var stunTcs))
+                        {
+                            var stunData = new byte[received];
+                            Buffer.BlockCopy(receiveBuffer, 0, stunData, 0, received);
+                            stunTcs.TrySetResult(stunData);
+                        }
+                        else if (!TryAutoLearnAndDispatch(receiveBuffer.AsMemory(0, received), receivedTime, (IPEndPoint)remoteEndpoint))
+                            Logger.Log($"V3TunnelCommunicator: Received packet from unknown endpoint: {remoteEndpoint}");


+    /// <summary>
+    /// Returns a string representation of this ping value.
+    /// Format: "50" for valid pings, or localized "Unknown" for invalid pings.
+    /// Note: Does not include the "ms" unit - callers should append the localized unit.
+    /// </summary>


SadPencil · 2026-07-02T04:19:10Z

Stop pings wavering between unknown and real value

umm, what if the player is indeed offline suddenly? could be better if we can show Unknown ping after several attempts (or maybe leave it as another PR)

Copilot

Pull request overview

Copilot reviewed 41 out of 43 changed files in this pull request and generated 2 comments.

            else
            {
-                connection.QueueMessage(QueuedMessageType.SYSTEM_MESSAGE, 9, "PART " + ChannelName);
+                connection.QueueMessage(QueuedMessageType.INSTANT_MESSAGE, 0, "PART " + ChannelName);


            tunnelHandler.CurrentTunnel = tunnel;
            AddNotice(string.Format("The game host has changed the tunnel server to: {0}".L10N("Client:Main:HostChangeTunnel"), tunnel.Name));

-            foreach (PlayerInfo pInfo in Players)
-            {
-                pInfo.Ping = -1;
-                UpdatePlayerPingIndicator(pInfo);
-            }
-
            CopyPlayerDataToUI();
            UpdatePing();
+


- Fix negotiated auto-learned P2P paths breaking in-game - Fix the game tunnel bridge thread dying permanently on transient socket errors - Fix tunnel-choice split brain after a failed P2P upgrade - Fix TunnelAck ambiguity - Fix pair status masking - Fix stale-packet corruption from overlapping renegotiation rounds - Fix disposed negotiators raising spurious failure/complete events - Fix a race where fire-and-forget ping tasks could touch the negotiator's disposed CancellationTokenSource (token now cached) - Fix V2 regression: STARTV2 carries the real tunnel address again and joiners re-sync their tunnel from it - Restrict TunnelFailed to two consecutive bad pings - Add 15-second lobby keepalives on negotiated relay tunnels and P2P paths so NAT mappings and tunnel registrations survive - Marshal negotiator events to the game thread, fixing the render-target NullReferenceException when negotiations completed

- Add a Renegotiate All debounce - Add failure notices for every pair transition to Failed (deduplicated), so the host now hears about failures between other players too - Add a renegotiate hint to the launch-blocked message and auto-open the negotiation status panel - Add visible error notices when a client can't process the host's STARTV3 message

- Rebuild the panel list view as a scrolling multicolumn listbox with ping bars - Report the full round-trip time between players instead of half - Prevent lobby ping icons flickering - Sort the list view worst-first - Align the panel's ping colors/bars with the lobby ping icon tiers - Center the "Tunnel Negotiation Status" panel title - Hide the local player's ping icon in dynamic mode - Show launch-blocked negotiation statuses as readable text - Add a host-only suggestion when kicking one player would significantly reduce the worst connection ping - Log the stale-failure-notification burst once per negotiator instead of once per tunnel

… up to date. Add a pre-launch connectivity check Fix duplicate L10N key Snapshot remote endpoints before storing them as P2P routing keys Reset player pings to unknown when host changes tunnel in V2 or V3 static mode.

Fix some nullable issues

Fix L10N strings

Fix game starting with null tunnel in v3 static mode when tunnel doesn't exist locally

Fix issue renegotiating with a player in game Probe all users in the pre-launch connectivity verification

Reset tunnelErrorMode on lobby setup/clear Set pings to unkown when TNLPNG -1 arrives Change tunnel picker to address:port instead of just address Make TunnelEventArgs.Tunnel nullable Make ApplyV3StartEntry fail if missing V3PlayerInfo record(s) Dedupe P2P candidates

Fix layout issue with the listbox in the negotiation status panel

11EJDE11 · 2026-07-04T06:16:57Z

Stop pings wavering between unknown and real value

umm, what if the player is indeed offline suddenly? could be better if we can show Unknown ping after several attempts (or maybe leave it as another PR)

Not entirely sure what you mean - it's a ping indicator, not a disconnect indicator. The client was incorrectly setting them to unknown as well - like when a player joins the lobby it resets everyone's to unknown. They could also be unknown from the "Only ping official tunnels" setting. There were some errors with the change I made though - corrected now.

Had to add a keep alive thing to keep the NAT mapped, so a lot of new code in the latest commits unfortunately. Good news is I've tested just about every scenario I can think of and it's all working brilliantly.

Copilot

Pull request overview

Copilot reviewed 44 out of 46 changed files in this pull request and generated 2 comments.

            else
            {
-                connection.QueueMessage(QueuedMessageType.SYSTEM_MESSAGE, 9, "PART " + ChannelName);
+                connection.QueueMessage(QueuedMessageType.INSTANT_MESSAGE, 0, "PART " + ChannelName);
            }


+        private void EvaluateTunnelHealth(CnCNetTunnel tunnel)
+        {
+            bool pingBad = tunnel.Ping.IsUnknown() || tunnel.Ping.Milliseconds > TUNNEL_FAILED_PING_AMOUNT;
+
+            if (!pingBad)


MahBoiDeveloper · 2025-11-22T11:37:51Z

                return;

-            XNAListBoxItem lbItem = GetItem(2, filteredIndex);
+            XNAListBoxItem lbItem = GetItem(3, filteredIndex);


Why this magic number has been changed?

MahBoiDeveloper · 2026-07-02T10:02:54Z

+
+

MahBoiDeveloper · 2026-07-02T10:03:43Z

+
+    /// <summary>
+    /// This tracks what each player reports about their negotiation with each other player
+    /// // reportingPlayer -> targetPlayer -> ping


Suggested change

/// // reportingPlayer -> targetPlayer -> ping

/// reportingPlayer -> targetPlayer -> ping

MahBoiDeveloper · 2026-07-02T10:05:17Z

+
+

Suggested change

MahBoiDeveloper · 2026-07-02T10:06:44Z

+        else
+            return $"Negotiations: {succeeded}/{total} complete";
+    }
+}


Suggested change

}

}

11EJDE11 added 20 commits October 10, 2025 06:34

Bump cncnet protocol version

66c9063

Add UseLegacyTunnels and UseDynamicTunnels settings

ac9a9b3

Add check for tunnelling method when receiving game broadcasts

94a006b

Allow displaying and selecting V3 tunnels in TunnelListBox

732152e

Update ping text in GameInformationPanel when dynamic tunnels are ena…

787eec3

…bled by host

Allow lobbies to be created with V3 tunnels

9127d7f

Fix null ping crash when hosted game uses dynamic tunnels

8f9e69d

Add V3PlayerInfo

0f85089

Add V3GameTunnelBridge Add V3TunnelCommunicator Add V3TunnelNegotiator Add TunnelFailed event Update supported tunnel versions

Add tunnel version to /tunnelinfo chatbox command

bff149e

Fixup GameCreationWindow control visibility Remove unnecessary tunnel parameter in V3PlayerInfo Add NegotiationStatusPanel Add tunnel negotiations to CnCNetGameLobby Add V3 tunnel support to CnCNetGameLobby

Separate out negotiation status information into new file

515a38a

Move to file-scoped namespaces Fix missing texture on status panel Fix issue with decider seeing OK instead of ping results

Update lobby ping indicators

ab92b94

Merge NEGSTAT and NEGPNG CTCP messages > NEGINFO

10628a0

Reset pings on TunnelModeChange

17a7f88

Fix an issue with automatic tunnel selection Style fixups Split TunnelChosenEventArgs into new file

Change to ping distinct IPs and update others

b455845

Remove debug call

5733cf1

Remove IDisposable on bridge

Rename files

eddf60d

Remove unecessary code

Add final ping to the tunnel choice packet send to non-decider

c2da73d

Rearrange some functions

f7e442a

Prevent duplicate complete messages

fa4b6e7

Better updating of player ping indicators

Increase timeout

34c49f6

MahBoiDeveloper moved this to 🔍 In Testing in XNA CnCNet Client Oct 24, 2025

MahBoiDeveloper added this to XNA CnCNet Client Oct 24, 2025

MahBoiDeveloper removed this from XNA CnCNet Client Oct 24, 2025

SadPencil force-pushed the develop branch from 47e2851 to 2597f10 Compare November 6, 2025 13:28

SadPencil force-pushed the develop branch from 9db87a8 to e0d174c Compare November 14, 2025 16:50

SadPencil reviewed Nov 17, 2025

View reviewed changes

11EJDE11 added 2 commits November 22, 2025 13:25

Merge branch 'develop' into new-v3-tunnels

3f4269b

Add nullable to various files

caf9f1e

Fix V2 tunnels not matching

SadPencil requested a review from Copilot July 1, 2026 16:14

Copilot started reviewing on behalf of SadPencil July 1, 2026 16:15 View session

Copilot AI reviewed Jul 1, 2026

View reviewed changes

11EJDE11 added 4 commits July 2, 2026 09:51

Lock RenegotiateAll to host

4538764

Various fixups

4cfed49

Update PingValue.ToString doc

5f1573a

Stop pings wavering between unknown and real value

eeffbb9

SadPencil requested a review from Copilot July 2, 2026 04:19

Copilot started reviewing on behalf of SadPencil July 2, 2026 04:19 View session

Copilot AI reviewed Jul 2, 2026

View reviewed changes

11EJDE11 added 14 commits July 3, 2026 08:43

Consolidate ping thresholds

12f213e

Fix some nullable issues

Remove duplicate code

d9eecbf

Fix L10N strings

Prevent rengotiations when in game

8ac199c

Performance improvements

de033ab

Fix game starting with null tunnel in v3 static mode when tunnel doesn't exist locally

Fix L10N issues

cdfb5b7

Fix issue renegotiating with a player in game Probe all users in the pre-launch connectivity verification

Formatting fixups

ba81dee

Fix an issue with kicking players that are still in game and using P2P

da8457f

Fix layout issue with the listbox in the negotiation status panel

Consolidate ping textures and colouring

0c3abfa

Fix an issue with tearing down autolearned P2P tunnels too early

835ca8c

SadPencil requested a review from Copilot July 4, 2026 08:04

Copilot started reviewing on behalf of SadPencil July 4, 2026 08:05 View session

Copilot AI reviewed Jul 4, 2026

View reviewed changes

MahBoiDeveloper reviewed Jul 4, 2026

View reviewed changes

	/// // reportingPlayer -> targetPlayer -> ping
	/// reportingPlayer -> targetPlayer -> ping

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How V3 Tunnels Work

Negotiation Process

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