c2c packet improvements (#485)

* implement over-engineered coinflip

* exchange hashes first so player2 cant easily cheat via guess/check

* fix self coinflip and multi coinflips with new method

* generalize to dice rolling

* fix function names

* bump to 1024 bytes, add timeout safety. make message too long say calculated length

* forgot to make dynamic change on decrypt

* missed a spot

* fix timeout breaking things

* revert dice roll

* revert lang file

Author: wagyourtail

src/main/java/net/earthcomputer/clientcommands/c2c/C2CPacket.java

@@ -1,7 +1,10 @@
 package net.earthcomputer.clientcommands.c2c;
 
+import com.mojang.brigadier.exceptions.CommandSyntaxException;
+import net.minecraft.network.PacketByteBuf;
+
 public interface C2CPacket {
-    void write(StringBuf buf);
+    void write(PacketByteBuf buf);
 
-    void apply(CCPacketListener listener);
+    void apply(CCPacketListener listener) throws CommandSyntaxException;
 }

src/main/java/net/earthcomputer/clientcommands/c2c/CCNetworkHandler.java

@@ -1,11 +1,14 @@
 package net.earthcomputer.clientcommands.c2c;
 
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
+import com.mojang.brigadier.exceptions.DynamicCommandExceptionType;
 import com.mojang.brigadier.exceptions.SimpleCommandExceptionType;
 import com.mojang.logging.LogUtils;
+import io.netty.buffer.Unpooled;
 import net.earthcomputer.clientcommands.c2c.packets.MessageC2CPacket;
 import net.minecraft.client.MinecraftClient;
 import net.minecraft.client.network.PlayerListEntry;
+import net.minecraft.network.PacketByteBuf;
 import net.minecraft.network.encryption.PlayerPublicKey;
 import net.minecraft.network.encryption.PublicPlayerSession;
 import net.minecraft.text.MutableText;
@@ -17,7 +20,7 @@
 
 public class CCNetworkHandler implements CCPacketListener {
 
-    private static final SimpleCommandExceptionType MESSAGE_TOO_LONG_EXCEPTION = new SimpleCommandExceptionType(Text.translatable("ccpacket.messageTooLong"));
+    private static final DynamicCommandExceptionType MESSAGE_TOO_LONG_EXCEPTION = new DynamicCommandExceptionType(d -> Text.translatable("ccpacket.messageTooLong", d));
     private static final SimpleCommandExceptionType PUBLIC_KEY_NOT_FOUND_EXCEPTION = new SimpleCommandExceptionType(Text.translatable("ccpacket.publicKeyNotFound"));
     private static final SimpleCommandExceptionType ENCRYPTION_FAILED_EXCEPTION = new SimpleCommandExceptionType(Text.translatable("ccpacket.encryptionFailed"));
 
@@ -47,21 +50,36 @@ public void sendPacket(C2CPacket packet, PlayerListEntry recipient) throws Comma
             throw PUBLIC_KEY_NOT_FOUND_EXCEPTION.create();
         }
         PublicKey key = ppk.data().key();
-        StringBuf buf = new StringBuf();
+        PacketByteBuf buf = new PacketByteBuf(Unpooled.buffer());
         buf.writeInt(id);
         packet.write(buf);
-        byte[] compressed = ConversionHelper.Gzip.compress(buf.bytes());
-        if (compressed.length > 245) {
-            throw MESSAGE_TOO_LONG_EXCEPTION.create();
+        byte[] compressed = ConversionHelper.Gzip.compress(buf.getWrittenBytes());
+        // split compressed into 245 byte chunks
+        int chunks = (compressed.length + 244) / 245;
+        byte[][] chunked = new byte[chunks][];
+        for (int i = 0; i < chunks; i++) {
+            int start = i * 245;
+            int end = Math.min(start + 245, compressed.length);
+            chunked[i] = new byte[end - start];
+            System.arraycopy(compressed, start, chunked[i], 0, end - start);
         }
-        byte[] encrypted = ConversionHelper.RsaEcb.encrypt(compressed, key);
-        if (encrypted == null || encrypted.length == 0) {
-            throw ENCRYPTION_FAILED_EXCEPTION.create();
+        // encrypt each chunk
+        byte[][] encrypted = new byte[chunks][];
+        for (int i = 0; i < chunks; i++) {
+            encrypted[i] = ConversionHelper.RsaEcb.encrypt(chunked[i], key);
+            if (encrypted[i] == null || encrypted[i].length == 0) {
+                throw ENCRYPTION_FAILED_EXCEPTION.create();
+            }
         }
-        String packetString = ConversionHelper.BaseUTF8.toUnicode(encrypted);
+        // join encrypted chunks into one byte array
+        byte[] joined = new byte[encrypted.length * 256];
+        for (int i = 0; i < encrypted.length; i++) {
+            System.arraycopy(encrypted[i], 0, joined, i * 256, 256);
+        }
+        String packetString = ConversionHelper.BaseUTF8.toUnicode(joined);
         String commandString = "w " + recipient.getProfile().getName() + " CCENC:" + packetString;
         if (commandString.length() >= 256) {
-            throw MESSAGE_TOO_LONG_EXCEPTION.create();
+            throw MESSAGE_TOO_LONG_EXCEPTION.create(commandString.length());
         }
         MinecraftClient.getInstance().getNetworkHandler().sendChatCommand(commandString);
         OutgoingPacketFilter.addPacket(packetString);

src/main/java/net/earthcomputer/clientcommands/c2c/CCPacketHandler.java

@@ -3,6 +3,7 @@
 import it.unimi.dsi.fastutil.objects.Object2IntMap;
 import it.unimi.dsi.fastutil.objects.Object2IntOpenHashMap;
 import net.earthcomputer.clientcommands.c2c.packets.MessageC2CPacket;
+import net.minecraft.network.PacketByteBuf;
 import net.minecraft.util.Util;
 import org.jetbrains.annotations.Nullable;
 
@@ -13,13 +14,13 @@
 public class CCPacketHandler {
 
     private static final Object2IntMap<Class<? extends C2CPacket>> packetIds = Util.make(new Object2IntOpenHashMap<>(), map -> map.defaultReturnValue(-1));
-    private static final List<Function<StringBuf, ? extends C2CPacket>> packetFactories = new ArrayList<>();
+    private static final List<Function<PacketByteBuf, ? extends C2CPacket>> packetFactories = new ArrayList<>();
 
     static {
         CCPacketHandler.register(MessageC2CPacket.class, MessageC2CPacket::new);
     }
 
-    public static <P extends C2CPacket> void register(Class<P> packet, Function<StringBuf, P> packetFactory) {
+    public static <P extends C2CPacket> void register(Class<P> packet, Function<PacketByteBuf, P> packetFactory) {
         int id = packetFactories.size();
         int i = packetIds.put(packet, id);
         if (i != -1) {
@@ -36,8 +37,8 @@ public static <P extends C2CPacket> Integer getId(Class<P> packet) {
     }
 
     @Nullable
-    public static C2CPacket createPacket(int id, StringBuf buf) {
-        Function<StringBuf, ? extends C2CPacket> function = packetFactories.get(id);
+    public static C2CPacket createPacket(int id, PacketByteBuf buf) {
+        Function<PacketByteBuf, ? extends C2CPacket> function = packetFactories.get(id);
         return function == null ? null : function.apply(buf);
     }
 }

src/main/java/net/earthcomputer/clientcommands/c2c/StringBuf.java

@@ -2,7 +2,9 @@
 
 import net.earthcomputer.clientcommands.c2c.C2CPacket;
 import net.earthcomputer.clientcommands.c2c.CCPacketListener;
-import net.earthcomputer.clientcommands.c2c.StringBuf;
+import net.minecraft.network.PacketByteBuf;
+
+import java.nio.ByteBuffer;
 
 public class MessageC2CPacket implements C2CPacket {
 
@@ -14,13 +16,13 @@ public MessageC2CPacket(String sender, String message) {
         this.message = message;
     }
 
-    public MessageC2CPacket(StringBuf raw) {
+    public MessageC2CPacket(PacketByteBuf raw) {
         this.sender = raw.readString();
         this.message = raw.readString();
     }
 
     @Override
-    public void write(StringBuf buf) {
+    public void write(PacketByteBuf buf) {
         buf.writeString(this.sender);
         buf.writeString(this.message);
     }

src/main/java/net/earthcomputer/clientcommands/c2c/packets/MessageC2CPacket.java

@@ -1,11 +1,14 @@
 package net.earthcomputer.clientcommands.mixin;
 
+import com.mojang.brigadier.exceptions.CommandSyntaxException;
+import io.netty.buffer.Unpooled;
 import net.earthcomputer.clientcommands.TempRules;
 import net.earthcomputer.clientcommands.c2c.*;
 import net.earthcomputer.clientcommands.interfaces.IHasPrivateKey;
 import net.minecraft.client.MinecraftClient;
 import net.minecraft.client.gui.hud.ChatHud;
 import net.minecraft.client.gui.hud.MessageIndicator;
+import net.minecraft.network.PacketByteBuf;
 import net.minecraft.network.message.MessageSignatureData;
 import net.minecraft.text.HoverEvent;
 import net.minecraft.text.Text;
@@ -17,7 +20,6 @@
 import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
-import java.nio.charset.StandardCharsets;
 import java.security.PrivateKey;
 import java.util.Arrays;
 import java.util.Optional;
@@ -61,29 +63,57 @@ private void handleIfPacket(Text content, CallbackInfo ci) {
 
     private static boolean handleC2CPacket(String content) {
         byte[] encrypted = ConversionHelper.BaseUTF8.fromUnicode(content);
-        encrypted = Arrays.copyOf(encrypted, 256);
+        // round down to multiple of 256 bytes
+        int length = encrypted.length & ~0xFF;
+        // copy to new array of arrays
+        byte[][] encryptedArrays = new byte[length / 256][];
+        for (int i = 0; i < length; i += 256) {
+            encryptedArrays[i / 256] = Arrays.copyOfRange(encrypted, i, i + 256);
+        }
         if (!(MinecraftClient.getInstance().getProfileKeys() instanceof IHasPrivateKey privateKeyHolder)) {
             return false;
         }
         Optional<PrivateKey> key = privateKeyHolder.getPrivateKey();
         if (key.isEmpty()) {
             return false;
         }
-        byte[] decrypted = ConversionHelper.RsaEcb.decrypt(encrypted, key.get());
-        if (decrypted == null) {
-            return false;
+        // decrypt
+        int len = 0;
+        byte[][] decryptedArrays = new byte[encryptedArrays.length][];
+        for (int i = 0; i < encryptedArrays.length; i++) {
+            decryptedArrays[i] = ConversionHelper.RsaEcb.decrypt(encryptedArrays[i], key.get());
+            if (decryptedArrays[i] == null) {
+                return false;
+            }
+            len += decryptedArrays[i].length;
+        }
+        // copy to new array
+        byte[] decrypted = new byte[len];
+        int pos = 0;
+        for (byte[] decryptedArray : decryptedArrays) {
+            System.arraycopy(decryptedArray, 0, decrypted, pos, decryptedArray.length);
+            pos += decryptedArray.length;
         }
         byte[] uncompressed = ConversionHelper.Gzip.uncompress(decrypted);
-        StringBuf buf = new StringBuf(new String(uncompressed, StandardCharsets.UTF_8));
+        PacketByteBuf buf = new PacketByteBuf(Unpooled.wrappedBuffer(uncompressed));
         int id = buf.readInt();
         C2CPacket c2CPacket = CCPacketHandler.createPacket(id, buf);
         if (c2CPacket == null) {
             return false;
         }
-        if (buf.getRemainingLength() > 0) {
+        if (buf.readableBytes() > 0) {
             return false;
         }
-        c2CPacket.apply(CCNetworkHandler.getInstance());
+        try {
+            c2CPacket.apply(CCNetworkHandler.getInstance());
+        } catch (CommandSyntaxException e) {
+            if (e.getRawMessage() instanceof Text) {
+                MinecraftClient.getInstance().inGameHud.getChatHud().addMessage((Text) e.getRawMessage());
+            }
+            e.printStackTrace();
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
         return true;
     }
 }

src/main/java/net/earthcomputer/clientcommands/mixin/MixinChatHud.java

@@ -299,7 +299,7 @@
   "snakeGame.title": "Snake",
   "snakeGame.score": "Score: %d",
 
-  "ccpacket.messageTooLong": "Message too long (max. 255 characters)",
+  "ccpacket.messageTooLong": "Message too long (max. 255 characters) got %s characters",
   "ccpacket.publicKeyNotFound": "Public key not found",
   "ccpacket.encryptionFailed": "Something failed while encrypting your message",
   "ccpacket.malformedPacket": "You have received a malformed C2C packet:",