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feat(net): track + echo movement sequence counters

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Sprint 1a of the audit remediation plan.

Extracts the 4 movement sequence counters from inbound server messages
and echoes them in outbound MoveToState + AutonomousPosition instead
of hardcoded zeros:

- instanceSequence (slot 8 in CreateObject PhysicsData timestamps)
- teleportSequence (slot 4, also from PlayerTeleport 0xF751)
- serverControlSequence (slot 5)
- forcePositionSequence (slot 6, also from UpdatePosition 0xF748)

Source: holtburger player/types.rs:237-245, mutations.rs:182-706.
The server uses these to detect stale/reordered movement packets.
Previously all zeros → server couldn't distinguish epoch boundaries.

Changes:
- CreateObject.Parsed: +4 sequence fields extracted from timestamps
- UpdatePosition.Parsed: +3 sequence fields from trailing u16s
- WorldSession: tracks 4 counters, updates from CreateObject/
  UpdatePosition/PlayerTeleport for the player's own GUID
- GameWindow: passes tracked values to MoveToState.Build and
  AutonomousPosition.Build

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Erik 2026-04-13 13:45:39 +02:00
parent 9e5258152d
commit 11974c2099
4 changed files with 74 additions and 18 deletions
Download patch file Download diff file Expand all files Collapse all files

16
src/AcDream.App/Rendering/GameWindow.cs
View file

@ -1753,10 +1753,10 @@ public sealed class GameWindow : IDisposable
cellId: wireCellId,
position: wirePos,
rotation: wireRot,
instanceSequence: 0,
serverControlSequence: 0,
teleportSequence: 0,
forcePositionSequence: 0);
instanceSequence: _liveSession.InstanceSequence,
serverControlSequence: _liveSession.ServerControlSequence,
teleportSequence: _liveSession.TeleportSequence,
forcePositionSequence: _liveSession.ForcePositionSequence);
_liveSession.SendGameAction(body);
}
@ -1768,10 +1768,10 @@ public sealed class GameWindow : IDisposable
cellId: wireCellId,
position: wirePos,
rotation: wireRot,
instanceSequence: 0,
serverControlSequence: 0,
teleportSequence: 0,
forcePositionSequence: 0);
instanceSequence: _liveSession.InstanceSequence,
serverControlSequence: _liveSession.ServerControlSequence,
teleportSequence: _liveSession.TeleportSequence,
forcePositionSequence: _liveSession.ForcePositionSequence);
_liveSession.SendGameAction(body);
}
}

18
src/AcDream.Core.Net/Messages/CreateObject.cs
View file

@ -92,7 +92,11 @@ public static class CreateObject
float? ObjScale,
string? Name,
ServerMotionState? MotionState,
uint? MotionTableId);
uint? MotionTableId,
ushort InstanceSequence = 0,
ushort TeleportSequence = 0,
ushort ServerControlSequence = 0,
ushort ForcePositionSequence = 0);
/// <summary>
/// The relevant subset of the server-sent <c>MovementData</c> /
@ -332,8 +336,15 @@ public static class CreateObject
if ((physicsFlags & PhysicsDescriptionFlag.DefaultScriptIntensity) != 0) pos += 4;
// 9 sequence timestamps, always present at end of PhysicsData.
// Indices per holtburger: 0=position, 4=teleport, 5=serverControl,
// 6=forcePosition, 8=instance.
if (body.Length - pos < 9 * 2) return PartialResult();
pos += 9 * 2; // each sequence is a ushort
var seqSpan = body.Slice(pos, 9 * 2);
ushort instanceSeq = BinaryPrimitives.ReadUInt16LittleEndian(seqSpan.Slice(8 * 2));
ushort teleportSeq = BinaryPrimitives.ReadUInt16LittleEndian(seqSpan.Slice(4 * 2));
ushort serverControlSeq = BinaryPrimitives.ReadUInt16LittleEndian(seqSpan.Slice(5 * 2));
ushort forcePositionSeq = BinaryPrimitives.ReadUInt16LittleEndian(seqSpan.Slice(6 * 2));
pos += 9 * 2;
AlignTo4(ref pos);
// --- WeenieHeader: read just the Name field (second after flags). ---
@ -349,7 +360,8 @@ public static class CreateObject
}
return new Parsed(guid, position, setupTableId, animParts,
textureChanges, subPalettes, basePaletteId, objScale, name, motionState, motionTableId);
textureChanges, subPalettes, basePaletteId, objScale, name, motionState, motionTableId,
instanceSeq, teleportSeq, serverControlSeq, forcePositionSeq);
// Local helper: if we ran out of fields past PhysicsData, still
// return the useful prefix (guid/position/setup/animParts/textures/palettes/scale/motion).

22
src/AcDream.Core.Net/Messages/UpdatePosition.cs
View file

@ -63,7 +63,10 @@ public static class UpdatePosition
uint Guid,
CreateObject.ServerPosition Position,
System.Numerics.Vector3? Velocity,
uint? PlacementId);
uint? PlacementId,
ushort InstanceSequence = 0,
ushort TeleportSequence = 0,
ushort ForcePositionSequence = 0);
/// <summary>
/// Parse a reassembled UpdatePosition body. <paramref name="body"/>
@ -144,17 +147,24 @@ public static class UpdatePosition
pos += 4;
}
// We deliberately skip the four u16 sequence numbers that
// follow; subscribers don't need them for simple rendering,
// and if the message is a deliberate out-of-order teleport the
// server always follows up with a fresher update anyway.
// Four u16 sequence numbers: instance, position, teleport, forcePosition.
ushort instSeq = 0, teleSeq = 0, forceSeq = 0;
if (body.Length - pos >= 8)
{
instSeq = BinaryPrimitives.ReadUInt16LittleEndian(body.Slice(pos));
// pos+2 = positionSequence (not tracked by movement)
teleSeq = BinaryPrimitives.ReadUInt16LittleEndian(body.Slice(pos + 4));
forceSeq = BinaryPrimitives.ReadUInt16LittleEndian(body.Slice(pos + 6));
pos += 8;
}
var serverPos = new CreateObject.ServerPosition(
LandblockId: cellId,
PositionX: px, PositionY: py, PositionZ: pz,
RotationW: rw, RotationX: rx, RotationY: ry, RotationZ: rz);
return new Parsed(guid, serverPos, velocity, placementId);
return new Parsed(guid, serverPos, velocity, placementId,
instSeq, teleSeq, forceSeq);
}
catch
{

36
src/AcDream.Core.Net/WorldSession.cs
View file

@ -116,6 +116,12 @@ public sealed class WorldSession : IDisposable
public event Action<State>? StateChanged;
public State CurrentState { get; private set; } = State.Disconnected;
/// <summary>Movement sequence counters for outbound MoveToState/AutonomousPosition.</summary>
public ushort InstanceSequence => _instanceSequence;
public ushort ServerControlSequence => _serverControlSequence;
public ushort TeleportSequence => _teleportSequence;
public ushort ForcePositionSequence => _forcePositionSequence;
public CharacterList.Parsed? Characters { get; private set; }
private readonly NetClient _net;
@ -129,6 +135,16 @@ public sealed class WorldSession : IDisposable
private uint _clientPacketSequence;
private uint _fragmentSequence = 1;
// Movement sequence counters — echoed back in every MoveToState and
// AutonomousPosition so the server can detect stale/reordered packets.
// Initialized from CreateObject PhysicsData timestamps, updated by
// UpdatePosition/UpdateMotion/PlayerTeleport. Per holtburger:
// instance=slot 8, teleport=slot 4, serverControl=slot 5, forcePosition=slot 6.
private ushort _instanceSequence;
private ushort _serverControlSequence;
private ushort _teleportSequence;
private ushort _forcePositionSequence;
// Phase A.3: background receive thread buffers raw UDP datagrams into
// a channel so the render thread never blocks on socket I/O.
private readonly Channel<byte[]> _inboundQueue =
@ -400,6 +416,15 @@ public sealed class WorldSession : IDisposable
var parsed = CreateObject.TryParse(body);
if (parsed is not null)
{
// Initialize sequence counters from the player's own CreateObject.
if (parsed.Value.Guid == Characters?.Characters.FirstOrDefault().Id)
{
_instanceSequence = parsed.Value.InstanceSequence;
_teleportSequence = parsed.Value.TeleportSequence;
_serverControlSequence = parsed.Value.ServerControlSequence;
_forcePositionSequence = parsed.Value.ForcePositionSequence;
}
EntitySpawned?.Invoke(new EntitySpawn(
parsed.Value.Guid,
parsed.Value.Position,
@ -440,6 +465,14 @@ public sealed class WorldSession : IDisposable
var posUpdate = UpdatePosition.TryParse(body);
if (posUpdate is not null)
{
// Update sequence counters from the player's own position updates.
if (posUpdate.Value.Guid == Characters?.Characters.FirstOrDefault().Id)
{
_instanceSequence = posUpdate.Value.InstanceSequence;
_teleportSequence = posUpdate.Value.TeleportSequence;
_forcePositionSequence = posUpdate.Value.ForcePositionSequence;
}
PositionUpdated?.Invoke(new EntityPositionUpdate(
posUpdate.Value.Guid,
posUpdate.Value.Position,
@ -457,10 +490,11 @@ public sealed class WorldSession : IDisposable
// movement; the LoginComplete is sent from GameWindow once
// the destination UpdatePosition is received and the player
// has been snapped to the new cell.
uint sequence = 0;
ushort sequence = 0;
if (body.Length >= 6)
sequence = System.Buffers.Binary.BinaryPrimitives.ReadUInt16LittleEndian(
body.AsSpan(4, 2));
_teleportSequence = sequence; // track for outbound movement messages
TeleportStarted?.Invoke(sequence);
}
}