Gracefully fall back for STATUS/HANDSHAKE/LOGIN states

src/main/java/com/velocitypowered/proxy/protocol/ProtocolConstants.java

@@ -3,7 +3,6 @@ package com.velocitypowered.proxy.protocol;
 import java.util.Arrays;
 
 public enum ProtocolConstants { ;
-    public static final int MINECRAFT_1_7_2 = 4;
     public static final int MINECRAFT_1_9 = 107;
     public static final int MINECRAFT_1_9_1 = 108;
     public static final int MINECRAFT_1_9_2 = 109;
@@ -15,7 +14,6 @@ public enum ProtocolConstants { ;
     public static final int MINECRAFT_1_12_1 = 338;
     public static final int MINECRAFT_1_12_2 = 340;
 
-    public static final int MINIMUM_VERSION_SUPPORTED = MINECRAFT_1_9;
     public static final int MINIMUM_GENERIC_VERSION = MINECRAFT_1_9;
 
     public static final int[] SUPPORTED_VERSIONS = new int[] {

src/main/java/com/velocitypowered/proxy/protocol/StateRegistry.java

@@ -106,8 +106,8 @@ public enum StateRegistry {
         }
     };
 
-    public final PacketRegistry CLIENTBOUND = new PacketRegistry(ProtocolConstants.Direction.CLIENTBOUND);
+    public final PacketRegistry CLIENTBOUND = new PacketRegistry(ProtocolConstants.Direction.CLIENTBOUND, this);
-    public final PacketRegistry SERVERBOUND = new PacketRegistry(ProtocolConstants.Direction.SERVERBOUND);
+    public final PacketRegistry SERVERBOUND = new PacketRegistry(ProtocolConstants.Direction.SERVERBOUND, this);
 
     public static class PacketRegistry {
         private static final IntObjectMap<int[]> LINKED_PROTOCOL_VERSIONS = new IntObjectHashMap<>();
@@ -120,10 +120,12 @@ public enum StateRegistry {
         }
 
         private final ProtocolConstants.Direction direction;
+        private final StateRegistry state;
         private final IntObjectMap<ProtocolVersion> versions = new IntObjectHashMap<>();
 
-        public PacketRegistry(ProtocolConstants.Direction direction) {
+        public PacketRegistry(Direction direction, StateRegistry state) {
             this.direction = direction;
+            this.state = state;
             for (int version : ProtocolConstants.SUPPORTED_VERSIONS) {
                 versions.put(version, new ProtocolVersion(version));
             }
@@ -133,6 +135,9 @@ public enum StateRegistry {
         public ProtocolVersion getVersion(final int version) {
             ProtocolVersion result = versions.get(version);
             if (result == null) {
+                if (state != PLAY) {
+                    return getVersion(MINIMUM_GENERIC_VERSION);
+                }
                 throw new IllegalArgumentException("Could not find data for protocol version " + version);
             }
             return result;

src/test/java/com/velocitypowered/proxy/protocol/PacketRegistryTest.java

@@ -1,7 +1,6 @@
 package com.velocitypowered.proxy.protocol;
 
 import com.velocitypowered.proxy.protocol.packets.Handshake;
-import com.velocitypowered.proxy.protocol.packets.KeepAlive;
 import org.junit.jupiter.api.Test;
 
 import static com.velocitypowered.proxy.protocol.ProtocolConstants.MINECRAFT_1_12;
@@ -11,7 +10,7 @@ import static org.junit.jupiter.api.Assertions.*;
 
 class PacketRegistryTest {
     private StateRegistry.PacketRegistry setupRegistry() {
-        StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(ProtocolConstants.Direction.CLIENTBOUND);
+        StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(ProtocolConstants.Direction.CLIENTBOUND, StateRegistry.HANDSHAKE);
         registry.register(Handshake.class, Handshake::new, new StateRegistry.PacketMapping(0x00, MINECRAFT_1_12));
         return registry;
     }
@@ -37,14 +36,14 @@ class PacketRegistryTest {
 
     @Test
     void failOnNoMappings() {
-        StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(ProtocolConstants.Direction.CLIENTBOUND);
+        StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(ProtocolConstants.Direction.CLIENTBOUND, StateRegistry.HANDSHAKE);
         assertThrows(IllegalArgumentException.class, () -> registry.register(Handshake.class, Handshake::new));
         assertThrows(IllegalArgumentException.class, () -> registry.getVersion(0).getPacketId(new Handshake()));
     }
 
     @Test
     void registrySuppliesCorrectPacketsByProtocol() {
-        StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(ProtocolConstants.Direction.CLIENTBOUND);
+        StateRegistry.PacketRegistry registry = new StateRegistry.PacketRegistry(ProtocolConstants.Direction.CLIENTBOUND, StateRegistry.HANDSHAKE);
         registry.register(Handshake.class, Handshake::new, new StateRegistry.PacketMapping(0x00, MINECRAFT_1_12),
                 new StateRegistry.PacketMapping(0x01, MINECRAFT_1_12_1));
         assertEquals(Handshake.class, registry.getVersion(MINECRAFT_1_12).createPacket(0x00).getClass());