From 516bd6ca73c80e14c230d5d1f35e9055c74b0cd2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Florian=20N=C3=BCcke?= <florian@nuecke.de>
Date: Sun, 13 Feb 2022 21:11:23 +0100
Subject: [PATCH] Add config for default ethernet frame TLL. Closes #101.

---
 src/main/java/li/cil/oc2/common/Config.java   |  2 ++
 .../NetworkConnectorBlockEntity.java          |  4 ++--
 .../blockentity/NetworkHubBlockEntity.java    | 21 +++++++++++++++++++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/src/main/java/li/cil/oc2/common/Config.java b/src/main/java/li/cil/oc2/common/Config.java
index 6ec47efe..c54f96d2 100644
--- a/src/main/java/li/cil/oc2/common/Config.java
+++ b/src/main/java/li/cil/oc2/common/Config.java
@@ -42,6 +42,8 @@ public final class Config {
 
     @Path("admin") public static UUID fakePlayerUUID = UUID.fromString("e39dd9a7-514f-4a2d-aa5e-b6030621416d");
     @Path("admin.network") public static int projectorAverageMaxBytesPerSecond = 160 * 1024;
+    @Path("admin.virtual_network") public static int ethernetFrameTimeToLive = 12;
+    @Path("admin.virtual_network") public static int hubEthernetFramesPerTick = 32;
 
     public static boolean computersUseEnergy() {
         return computerEnergyPerTick > 0 && computerEnergyStorage > 0;
diff --git a/src/main/java/li/cil/oc2/common/blockentity/NetworkConnectorBlockEntity.java b/src/main/java/li/cil/oc2/common/blockentity/NetworkConnectorBlockEntity.java
index dc744ee6..93ba7c98 100644
--- a/src/main/java/li/cil/oc2/common/blockentity/NetworkConnectorBlockEntity.java
+++ b/src/main/java/li/cil/oc2/common/blockentity/NetworkConnectorBlockEntity.java
@@ -4,6 +4,7 @@ package li.cil.oc2.common.blockentity;
 
 import li.cil.oc2.api.capabilities.NetworkInterface;
 import li.cil.oc2.client.renderer.NetworkCableRenderer;
+import li.cil.oc2.common.Config;
 import li.cil.oc2.common.block.NetworkConnectorBlock;
 import li.cil.oc2.common.capabilities.Capabilities;
 import li.cil.oc2.common.item.Items;
@@ -53,7 +54,6 @@ public final class NetworkConnectorBlockEntity extends ModBlockEntity implements
     private static final int RETRY_UNLOADED_CHUNK_INTERVAL = TickUtils.toTicks(Duration.ofSeconds(5));
     private static final int MAX_CONNECTION_COUNT = 2;
     private static final int MAX_CONNECTION_DISTANCE = 16;
-    private static final int INITIAL_PACKET_TIME_TO_LIVE = 12;
     private static final int BYTES_PER_TICK = 64 * 1024 / TickUtils.toTicks(Duration.ofSeconds(1)); // bytes / sec -> bytes / tick
     private static final int MIN_ETHERNET_FRAME_SIZE = 42;
     private static final int TTL_COST = 1;
@@ -197,7 +197,7 @@ public final class NetworkConnectorBlockEntity extends ModBlockEntity implements
         byte[] frame;
         while ((frame = source.readEthernetFrame()) != null && byteBudget > 0) {
             byteBudget -= Math.max(frame.length, MIN_ETHERNET_FRAME_SIZE); // Avoid bogus packets messing with us.
-            networkInterface.writeEthernetFrame(source, frame, INITIAL_PACKET_TIME_TO_LIVE);
+            networkInterface.writeEthernetFrame(source, frame, Config.ethernetFrameTimeToLive);
         }
     }
 
diff --git a/src/main/java/li/cil/oc2/common/blockentity/NetworkHubBlockEntity.java b/src/main/java/li/cil/oc2/common/blockentity/NetworkHubBlockEntity.java
index eb3334d3..4e3f1e2a 100644
--- a/src/main/java/li/cil/oc2/common/blockentity/NetworkHubBlockEntity.java
+++ b/src/main/java/li/cil/oc2/common/blockentity/NetworkHubBlockEntity.java
@@ -3,6 +3,7 @@
 package li.cil.oc2.common.blockentity;
 
 import li.cil.oc2.api.capabilities.NetworkInterface;
+import li.cil.oc2.common.Config;
 import li.cil.oc2.common.Constants;
 import li.cil.oc2.common.capabilities.Capabilities;
 import li.cil.oc2.common.util.LazyOptionalUtils;
@@ -21,6 +22,9 @@ import java.util.stream.Stream;
 public final class NetworkHubBlockEntity extends ModBlockEntity implements NetworkInterface {
     private static final int TTL_COST = 1;
 
+    private int frameCount;
+    private long lastGameTime;
+
     ///////////////////////////////////////////////////////////////////
 
     private final NetworkInterface[] adjacentBlockInterfaces = new NetworkInterface[Constants.BLOCK_FACE_COUNT];
@@ -45,6 +49,23 @@ public final class NetworkHubBlockEntity extends ModBlockEntity implements Netwo
 
     @Override
     public void writeEthernetFrame(final NetworkInterface source, final byte[] frame, final int timeToLive) {
+        if (level == null) {
+            return;
+        }
+
+        // Give a cap on top of the TLL, just in case trolls intentionally build
+        // loops that exponentially multiply ethernet frames after people crank up
+        // the default TTL.
+        final long gameTime = level.getGameTime();
+        if (gameTime > lastGameTime) {
+            lastGameTime = gameTime;
+            frameCount = 1;
+        } else if (frameCount > Config.hubEthernetFramesPerTick) {
+            return;
+        } else {
+            frameCount++;
+        }
+
         getAdjacentInterfaces().forEach(adjacentInterface -> {
             if (adjacentInterface != source) {
                 adjacentInterface.writeEthernetFrame(this, frame, timeToLive - TTL_COST);