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Server-authoritative damage validation + death broadcast #20

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Server-authoritative damage validation + death broadcast #20

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77 changes: 73 additions & 4 deletions TcpServer/Program.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,10 @@ class TcpServer
private const int SERIAL_X = 12345;
private const int SERIAL_Y = 67890;

// Server-authoritative anti-cheat: no single hit may exceed this (defeats spoofed one-shots).
// TODO v2: per-weapon max from a weapon table, distance/line-of-sight + fire-rate limits, server-owned HP.
private const float MAX_DAMAGE = 200f;

public TcpServer(int port)
{
listener = new TcpListener(IPAddress.IPv6Any, port);
Expand Down Expand Up @@ -223,20 +227,68 @@ private void HandleGameActions(ByteBuffer buffer, int id)
Console.WriteLine($"Player \"{id}\" fired their weapon.");
break;

case 2: // Damage dealt to another player
case 2: // Damage dealt to another player (SERVER-AUTHORITATIVE: validated before relay)
int receiverId = buffer.GetInt();
float damageAmount = buffer.GetFloat();
int damageCriticalCode = buffer.GetInt();
float posX = buffer.GetFloat();
float posY = buffer.GetFloat();
float posZ = buffer.GetFloat();
Console.WriteLine($"Player \"{id}\" dealt \"{damageAmount}\" damage to Player \"{receiverId}\" (critical code \"{damageCriticalCode}\") at (\"{posX}\", \"{posY}\", \"{posZ}\")");

PlayerData attackerData, victimData;
lock (playerDatas)
{
playerDatas.TryGetValue(id, out attackerData);
playerDatas.TryGetValue(receiverId, out victimData);
}

string rejectReason = null;
if (attackerData == null || victimData == null) rejectReason = "unknown player";
else if (receiverId == id) rejectReason = "self-damage";
else if (damageAmount <= 0f) rejectReason = "non-positive damage";
else if (damageAmount > MAX_DAMAGE) rejectReason = $"damage {damageAmount} over cap {MAX_DAMAGE}";

if (rejectReason != null)
{
// The server is the authority: drop the packet, the victim never takes the hit.
Console.WriteLine($"[ANTICHEAT] REJECTED damage from \"{id}\" -> \"{receiverId}\" ({damageAmount}): {rejectReason}");
break;
}

Console.WriteLine($"Player \"{id}\" dealt \"{damageAmount}\" damage to Player \"{receiverId}\" (crit \"{damageCriticalCode}\")");

// relay the validated damage ONLY to the victim; their client applies it
// (client handles protocol 2 / argument 4 -> DamageReceived(dealerId, amount, crit, pos))
ByteBuffer dmgRelay = new ByteBuffer();
dmgRelay.Put((byte)2); // protocol
dmgRelay.Put((byte)4); // argument 4 = damage received
dmgRelay.Put(id); // dealerId (attacker)
dmgRelay.Put(damageAmount);
dmgRelay.Put(damageCriticalCode);
dmgRelay.Put(posX);
dmgRelay.Put(posY);
dmgRelay.Put(posZ);
SendToClient(receiverId, dmgRelay.Trim().Get());
break;

case 3: // Player died
case 3: // Player died (victim reports it after taking server-approved damage)
int killerId = buffer.GetInt();
int criticalCode = buffer.GetInt();
Console.WriteLine($"Player \"{id}\" was killed by Player \"{killerId}\" with critical code \"{criticalCode}\"");
Console.WriteLine($"Player \"{id}\" was killed by Player \"{killerId}\" (crit \"{criticalCode}\")");
lock (playerDatas)
{
if (playerDatas.TryGetValue(id, out var deadData)) deadData.deaths++;
if (killerId >= 0 && playerDatas.TryGetValue(killerId, out var killerData)) killerData.kills++;
}
// broadcast the death so every client sees it
// (client handles protocol 2 / argument 5 -> PlayerDied(killedId, killerId, crit))
ByteBuffer deathBroadcast = new ByteBuffer();
deathBroadcast.Put((byte)2); // protocol
deathBroadcast.Put((byte)5); // argument 5 = player died
deathBroadcast.Put(id); // killedId
deathBroadcast.Put(killerId); // killerId
deathBroadcast.Put(criticalCode);
SendToAllClients(deathBroadcast.Trim().Get());
break;

case 4: // Chat message
Expand Down Expand Up @@ -322,6 +374,23 @@ private void SendToOtherClients(byte[] data, int exceptId)
}
}

private void SendToClient(int targetId, byte[] data)
{
lock (clients)
{
if (clients.TryGetValue(targetId, out var client))
{
try
{
NetworkStream ns = client.GetStream();
if (ns.CanWrite)
ns.Write(data, 0, data.Length);
}
catch { }
}
}
}

public void Stop()
{
isRunning = false;
Expand Down