fix(multiplayer): add LAN server detection for custom theme

src-theme/src/integration/rest.ts

@@ -268,6 +268,13 @@ export async function getServers(): Promise<Server[]> {
     return data;
 }
 
+export async function getLanServers(): Promise<Server[]> {
+    const response = await fetch(`${API_BASE}/client/servers/lan`);
+    const data: Server[] = await response.json();
+
+    return data;
+}
+
 export async function connectToServer(address: string) {
     await fetch(`${API_BASE}/client/servers/connect`, {
         method: "POST",

src-theme/src/integration/types.ts

@@ -304,6 +304,7 @@ export interface Server {
     version: string;
     ping: number;
     resourcePackPolicy: string;
+    lan?: boolean;
 }
 
 export interface TextComponent {

src-theme/src/routes/menu/multiplayer/Multiplayer.svelte

@@ -8,11 +8,12 @@
     import Search from "../common/Search.svelte";
     import MenuListItem from "../common/menulist/MenuListItem.svelte";
     import MenuListItemButton from "../common/menulist/MenuListItemButton.svelte";
-    import {onMount} from "svelte";
+    import {onDestroy, onMount} from "svelte";
     import {
         browse,
         connectToServer,
         getClientInfo,
+        getLanServers,
         getModule,
         getProtocols,
         getSelectedProtocol,
@@ -49,20 +50,21 @@
     let currentEditServer: Server | null = null;
 
     $: {
-        let filteredServers = servers;
+        let combined = [...servers, ...lanServers];
         if (onlineOnly) {
-            filteredServers = filteredServers.filter(s => s.ping > 0);
+            combined = combined.filter(s => s.ping > 0);
         }
         if (searchQuery) {
-            filteredServers = filteredServers.filter(s => s.name.toLowerCase().includes(searchQuery.toLowerCase()));
+            combined = combined.filter(s => s.name.toLowerCase().includes(searchQuery.toLowerCase()));
         }
-        renderedServers = filteredServers;
+        renderedServers = combined;
     }
 
     let clientInfo: ClientInfo | null = null;
     let autoConfig = false;
     let spooferConfigurable: ConfigurableSetting | null = null;
     let servers: Server[] = [];
+    let lanServers: Server[] = [];
     let renderedServers: Server[] = [];
     let protocols: Protocol[] = [];
     let selectedProtocol: Protocol = {
@@ -78,14 +80,20 @@
     // This is a hack and there should be a better solution.
     let timesSorted = 0;
 
+    let lanPollInterval: ReturnType<typeof setInterval> | null = null;
+
     onMount(async () => {
         clientInfo = await getClientInfo();
         spooferConfigurable = await getSpooferSettings();
         autoConfig = (await getModule("AutoConfig")).enabled;
         await refreshServers();
-        renderedServers = servers;
+        await refreshLanServers();
+        renderedServers = [...servers, ...lanServers];
         protocols = await getProtocols();
         selectedProtocol = await getSelectedProtocol();
+
+        // Poll for LAN servers every 3 seconds
+        lanPollInterval = setInterval(refreshLanServers, 3000);
     });
 
     listen("serverPinged", (pingedEvent: ServerPingedEvent) => {
@@ -107,6 +115,20 @@
         servers = await getServers();
     }
 
+    async function refreshLanServers() {
+        try {
+            lanServers = await getLanServers();
+        } catch {
+            // Silently ignore LAN server fetch errors to avoid spamming console
+        }
+    }
+
+    onDestroy(() => {
+        if (lanPollInterval) {
+            clearInterval(lanPollInterval);
+        }
+    });
+
     async function removeServer(index: number) {
         await removeServerRest(index);
         await refreshServers();
@@ -139,7 +161,7 @@
     async function handleServerSort(e: CustomEvent<{ newOrder: number[] }>) {
         await orderServers(e.detail.newOrder);
         await refreshServers();
-        renderedServers = servers;
+        renderedServers = [...servers, ...lanServers];
         timesSorted++; // See declaration
     }
 
@@ -192,7 +214,7 @@
         {/if}
     </OptionBar>
 
-    <MenuList sortable={renderedServers.length === servers.length} elementCount={servers.length}
+    <MenuList sortable={renderedServers.length === servers.length && lanServers.length === 0} elementCount={servers.length}
               on:sort={handleServerSort}>
         {#key timesSorted}
             {#each renderedServers as server}
@@ -208,15 +230,20 @@
                                    textComponent={server.ping <= 0 ? "§CCan't connect to server" : server.label}/>
 
                     <svelte:fragment slot="tag">
+                        {#if server.lan}
+                            <MenuListItemTag text="LAN"/>
+                        {/if}
                         {#if server.ping > 0}
                             <MenuListItemTag text="{server.players.online}/{server.players.max} Players"/>
                             <MenuListItemTag text={server.version}/>
                         {/if}
                     </svelte:fragment>
 
                     <svelte:fragment slot="active-visible">
-                        <MenuListItemButton title="Remove" icon="trash" on:click={() => removeServer(server.id)}/>
-                        <MenuListItemButton title="Edit" icon="pen-2" on:click={() => editServer(server)}/>
+                        {#if !server.lan}
+                            <MenuListItemButton title="Remove" icon="trash" on:click={() => removeServer(server.id)}/>
+                            <MenuListItemButton title="Edit" icon="pen-2" on:click={() => editServer(server)}/>
+                        {/if}
                     </svelte:fragment>
 
                     <svelte:fragment slot="always-visible">

src/main/kotlin/net/ccbluex/liquidbounce/integration/interop/protocol/rest/v1/game/ServerListFunctions.kt

@@ -20,9 +20,11 @@
 package net.ccbluex.liquidbounce.integration.interop.protocol.rest.v1.game
 
 import com.google.gson.JsonArray
+import com.google.gson.JsonObject
 import net.ccbluex.liquidbounce.config.gson.interopGson
 import net.ccbluex.liquidbounce.config.gson.serializer.minecraft.ResourcePolicy
 import net.ccbluex.liquidbounce.event.EventListener
+import net.ccbluex.liquidbounce.event.events.ClientShutdownEvent
 import net.ccbluex.liquidbounce.event.events.GameTickEvent
 import net.ccbluex.liquidbounce.event.events.ScreenEvent
 import net.ccbluex.liquidbounce.event.handler
@@ -41,13 +43,16 @@ import net.minecraft.client.multiplayer.ServerData.ServerPackStatus
 import net.minecraft.client.multiplayer.ServerList
 import net.minecraft.client.multiplayer.ServerStatusPinger
 import net.minecraft.client.multiplayer.resolver.ServerAddress
+import net.minecraft.client.server.LanServer
+import net.minecraft.client.server.LanServerDetection
 import net.minecraft.network.chat.CommonComponents
 import net.minecraft.network.chat.Component
 import net.minecraft.server.network.EventLoopGroupHolder
 import net.minecraft.util.CommonColors
 import net.minecraft.util.Util
 import java.net.UnknownHostException
 import java.util.concurrent.CompletableFuture
+import java.util.concurrent.ConcurrentHashMap
 import java.util.concurrent.Future
 
 // GET /api/v1/client/servers
@@ -184,6 +189,70 @@ object ActiveServerList : EventListener {
 
     private val pingTasks = mutableListOf<Future<*>>()
 
+    // LAN server detection using vanilla Minecraft's LanServerDetection
+    private val lanServerList = LanServerDetection.LanServerList()
+    private var lanDetector: LanServerDetection.LanServerDetector? = null
+
+    // Track ServerData for each LAN server (for ping info)
+    private val lanServerData = ConcurrentHashMap<String, ServerData>()
+
+    init {
+        startLanDetection()
+    }
+
+    @Suppress("unused")
+    private val shutdownHandler = handler<ClientShutdownEvent> {
+        stopLanDetection()
+    }
+
+    private fun startLanDetection() {
+        try {
+            lanDetector = LanServerDetection.LanServerDetector(lanServerList).apply { start() }
+        } catch (e: Exception) {
+            logger.warn("Unable to start LAN server detection: {}", e.message)
+        }
+    }
+
+    private fun stopLanDetection() {
+        lanDetector?.interrupt()
+        lanDetector = null
+        lanServerData.clear()
+    }
+
+    /**
+     * Returns the list of currently detected LAN servers with full Server-compatible JSON fields.
+     * Uses negative IDs to avoid collision with regular server IDs.
+     */
+    fun getLanServers(): List<JsonObject> {
+        // Check for new servers from vanilla detector
+        lanServerList.takeDirtyServers()?.forEach { lanServer ->
+            val address = lanServer.address
+            if (!lanServerData.containsKey(address)) {
+                val serverData = ServerData(lanServer.motd, address, ServerData.Type.LAN)
+                lanServerData[address] = serverData
+                ping(serverData)
+            }
+        }
+
+        return lanServerData.entries.mapIndexed { index, (_, serverData) ->
+            val json = interopGson.toJsonTree(serverData)
+
+            if (!json.isJsonObject) {
+                logger.warn("Failed to convert LAN serverData to json")
+                return@mapIndexed null
+            }
+
+            json.asJsonObject.apply {
+                // Use negative IDs to distinguish from regular servers (e.g., -1, -2, ...)
+                addProperty("id", -(index + 1))
+                addProperty("lan", true)
+                // Add online status (ServerInfoSerializer uses status enum, frontend expects boolean)
+                addProperty("online", serverData.state() == ServerData.State.SUCCESSFUL ||
+                    serverData.state() == ServerData.State.INCOMPATIBLE)
+            }
+        }.filterNotNull()
+    }
+
     private fun cancelTasks() {
         pingTasks.forEach { it.cancel(true) }
         pingTasks.clear()
@@ -248,8 +317,18 @@ val ServerList.servers: List<ServerData>
 
 fun ServerList.getByAddress(address: String) = servers.firstOrNull { it.ip == address }
 
+// GET /api/v1/client/servers/lan
+private fun Routing.getLanServers() = get("/lan") {
+    runCatching {
+        val servers = JsonArray()
+        ActiveServerList.getLanServers().forEach { servers.add(it) }
+        call.respond(servers)
+    }.getOrElse { call.internalServerError("Failed to get LAN servers due to ${it.message}") }
+}
+
 internal fun Routing.serverListRoutes() = route("/servers") {
     getServers()
+    getLanServers()
     putAddServer()
     deleteServer()
     putEditServer()