Add client and server patching functionality to support custom authentication domain and token system

BUILD.md

@@ -36,19 +36,4 @@ npm run build:mac
 npm run build:all
 ```
 
-## Output
+Built executables will be in the `dist/` directory
-
-Built executables will be in the `dist/` directory:
-
-- **Windows**: `Hytale F2P Launcher Setup.exe` (NSIS installer) and `Hytale F2P Launcher.exe` (portable)
-- **Linux**: `Hytale F2P Launcher.AppImage` and `Hytale F2P Launcher.deb`
-- **macOS**: `Hytale F2P Launcher.dmg` and `Hytale F2P Launcher.zip`
-
-## Notes
-
-- Icons need to be placed in `build/` directory:
-  - `icon.ico` for Windows
-  - `icon.png` for Linux
-  - `icon.icns` for macOS
-- To build for macOS on non-Mac systems, you'll need to run it on a Mac or use a CI/CD service
-

SERVER.md

@@ -4,7 +4,7 @@
 
 **Download server file:**
 ```
-http://3.10.208.30:3002/server
+https://files.hytalef2p.com/server
 ```
 
 **Replace the file here:**  

backend/core/config.js

@@ -2,6 +2,35 @@ const fs = require('fs');
 const path = require('path');
 const os = require('os');
 
+// Default auth domain - can be overridden by env var or config
+const DEFAULT_AUTH_DOMAIN = 'sanasol.ws';
+
+// Get auth domain from env, config, or default
+function getAuthDomain() {
+  // First check environment variable
+  if (process.env.HYTALE_AUTH_DOMAIN) {
+    return process.env.HYTALE_AUTH_DOMAIN;
+  }
+  // Then check config file
+  const config = loadConfig();
+  if (config.authDomain) {
+    return config.authDomain;
+  }
+  // Fall back to default
+  return DEFAULT_AUTH_DOMAIN;
+}
+
+// Get full auth server URL
+function getAuthServerUrl() {
+  const domain = getAuthDomain();
+  return `https://sessions.${domain}`;
+}
+
+// Save auth domain to config
+function saveAuthDomain(domain) {
+  saveConfig({ authDomain: domain || DEFAULT_AUTH_DOMAIN });
+}
+
 function getAppDir() {
   const home = os.homedir();
   if (process.platform === 'win32') {
@@ -159,5 +188,10 @@ module.exports = {
   loadModsFromConfig,
   isFirstLaunch,
   markAsLaunched,
-  CONFIG_FILE
+  CONFIG_FILE,
+  // Auth domain config
+  DEFAULT_AUTH_DOMAIN,
+  getAuthDomain,
+  getAuthServerUrl,
+  saveAuthDomain
 };

backend/managers/gameLauncher.js

@@ -1,17 +1,105 @@
 const fs = require('fs');
 const path = require('path');
+const crypto = require('crypto');
 const { exec } = require('child_process');
 const { promisify } = require('util');
 const { spawn } = require('child_process');
+const { v4: uuidv4 } = require('uuid');
 const { getResolvedAppDir, findClientPath } = require('../core/paths');
 const { setupWaylandEnvironment } = require('../utils/platformUtils');
-const { saveUsername, saveInstallPath, loadJavaPath, getUuidForUser } = require('../core/config');
+const { saveUsername, saveInstallPath, loadJavaPath, getUuidForUser, getAuthServerUrl, getAuthDomain } = require('../core/config');
 const { resolveJavaPath, getJavaExec, getBundledJavaPath, detectSystemJava, JAVA_EXECUTABLE } = require('./javaManager');
 const { getInstalledClientVersion, getLatestClientVersion } = require('../services/versionManager');
 const { updateGameFiles } = require('./gameManager');
 
+// Client patcher for custom auth server (sanasol.ws)
+let clientPatcher = null;
+try {
+  clientPatcher = require('../utils/clientPatcher');
+} catch (err) {
+  console.log('[Launcher] Client patcher not available:', err.message);
+}
+
 const execAsync = promisify(exec);
 
+// Fetch tokens from the auth server (properly signed with server's Ed25519 key)
+async function fetchAuthTokens(uuid, name) {
+  const authServerUrl = getAuthServerUrl();
+  try {
+    console.log(`Fetching auth tokens from ${authServerUrl}/game-session/child`);
+
+    const response = await fetch(`${authServerUrl}/game-session/child`, {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json'
+      },
+      body: JSON.stringify({
+        uuid: uuid,
+        name: name,
+        scopes: ['hytale:server', 'hytale:client']
+      })
+    });
+
+    if (!response.ok) {
+      throw new Error(`Auth server returned ${response.status}`);
+    }
+
+    const data = await response.json();
+    console.log('Auth tokens received from server');
+
+    return {
+      identityToken: data.IdentityToken || data.identityToken,
+      sessionToken: data.SessionToken || data.sessionToken
+    };
+  } catch (error) {
+    console.error('Failed to fetch auth tokens:', error.message);
+    // Fallback to local generation if server unavailable
+    return generateLocalTokens(uuid, name);
+  }
+}
+
+// Fallback: Generate tokens locally (won't pass signature validation but allows offline testing)
+function generateLocalTokens(uuid, name) {
+  console.log('Using locally generated tokens (fallback mode)');
+  const authServerUrl = getAuthServerUrl();
+  const now = Math.floor(Date.now() / 1000);
+  const exp = now + 36000;
+
+  const header = Buffer.from(JSON.stringify({
+    alg: 'EdDSA',
+    kid: '2025-10-01',
+    typ: 'JWT'
+  })).toString('base64url');
+
+  const identityPayload = Buffer.from(JSON.stringify({
+    sub: uuid,
+    name: name,
+    username: name,
+    entitlements: ['game.base'],
+    scope: 'hytale:server hytale:client',
+    iat: now,
+    exp: exp,
+    iss: authServerUrl,
+    jti: uuidv4()
+  })).toString('base64url');
+
+  const sessionPayload = Buffer.from(JSON.stringify({
+    sub: uuid,
+    scope: 'hytale:server',
+    iat: now,
+    exp: exp,
+    iss: authServerUrl,
+    jti: uuidv4()
+  })).toString('base64url');
+
+  const signature = crypto.randomBytes(64).toString('base64url');
+
+  return {
+    identityToken: `${header}.${identityPayload}.${signature}`,
+    sessionToken: `${header}.${sessionPayload}.${signature}`
+  };
+}
+
 async function launchGame(playerName = 'Player', progressCallback, javaPathOverride, installPathOverride) {
   const customAppDir = getResolvedAppDir(installPathOverride);
   const customGameDir = path.join(customAppDir, 'release', 'package', 'game', 'latest');
@@ -53,6 +141,51 @@ async function launchGame(playerName = 'Player', progressCallback, javaPathOverr
     }
   }
 
+  const uuid = getUuidForUser(playerName);
+
+  // Fetch tokens from auth server
+  if (progressCallback) {
+    progressCallback('Fetching authentication tokens...', null, null, null, null);
+  }
+  const { identityToken, sessionToken } = await fetchAuthTokens(uuid, playerName);
+
+  // Patch client and server binaries to use custom auth server (BEFORE signing on macOS)
+  const authDomain = getAuthDomain();
+  if (clientPatcher) {
+    try {
+      if (progressCallback) {
+        progressCallback('Patching game for custom server...', null, null, null, null);
+      }
+      console.log(`Patching game binaries for ${authDomain}...`);
+
+      const patchResult = await clientPatcher.ensureClientPatched(gameLatest, (msg, percent) => {
+        console.log(`[Patcher] ${msg}`);
+        if (progressCallback && msg) {
+          progressCallback(msg, percent, null, null, null);
+        }
+      });
+
+      if (patchResult.success) {
+        if (patchResult.alreadyPatched) {
+          console.log(`Game already patched for ${authDomain}`);
+        } else {
+          console.log(`Game patched successfully (${patchResult.patchCount} total occurrences)`);
+          if (patchResult.client) {
+            console.log(`  Client: ${patchResult.client.patchCount || 0} occurrences`);
+          }
+          if (patchResult.server) {
+            console.log(`  Server: ${patchResult.server.patchCount || 0} occurrences`);
+          }
+        }
+      } else {
+        console.warn('Game patching failed:', patchResult.error);
+      }
+    } catch (patchError) {
+      console.warn('Game patching failed (game may not connect to custom server):', patchError.message);
+    }
+  }
+
+  // macOS: Sign binaries AFTER patching so the patched binaries have valid signatures
   if (process.platform === 'darwin') {
     try {
       const appBundle = path.join(gameLatest, 'Client', 'Hytale.app');
@@ -66,10 +199,10 @@ async function launchGame(playerName = 'Player', progressCallback, javaPathOverr
 
       if (fs.existsSync(appBundle)) {
         await signPath(appBundle, true);
-        console.log('Signed macOS app bundle');
+        console.log('Signed macOS app bundle (after patching)');
       } else {
         await signPath(path.dirname(clientPath), true);
-        console.log('Signed macOS client binary');
+        console.log('Signed macOS client binary (after patching)');
       }
 
       if (javaBin && fs.existsSync(javaBin)) {
@@ -85,7 +218,7 @@ async function launchGame(playerName = 'Player', progressCallback, javaPathOverr
       if (fs.existsSync(serverDir)) {
         await execAsync(`xattr -cr "${serverDir}"`).catch(() => {});
         await execAsync(`find "${serverDir}" -type f -perm +111 -exec codesign --force --sign - {} \\;`).catch(() => {});
-        console.log('Signed server binaries');
+        console.log('Signed server binaries (after patching)');
       }
 
       if (javaBin && fs.existsSync(javaBin)) {
@@ -113,13 +246,14 @@ exec "$REAL_JAVA" "\${ARGS[@]}"
     }
   }
 
-  const uuid = getUuidForUser(playerName);
   const args = [
     '--app-dir', gameLatest,
     '--java-exec', javaBin,
-    '--auth-mode', 'offline',
+    '--auth-mode', 'authenticated',
     '--uuid', uuid,
     '--name', playerName,
+    '--identity-token', identityToken,
+    '--session-token', sessionToken,
     '--user-dir', userDataDir
   ];
 

backend/utils/clientPatcher.js

@@ -0,0 +1,511 @@
+const fs = require('fs');
+const path = require('path');
+const crypto = require('crypto');
+const AdmZip = require('adm-zip');
+
+// Domain configuration
+const ORIGINAL_DOMAIN = 'hytale.com';
+
+// Get target domain from config or environment
+function getTargetDomain() {
+  // Check environment variable first
+  if (process.env.HYTALE_AUTH_DOMAIN) {
+    return process.env.HYTALE_AUTH_DOMAIN;
+  }
+  // Try to load from config
+  try {
+    const { getAuthDomain } = require('../core/config');
+    return getAuthDomain();
+  } catch (e) {
+    // Config not available, use default
+    return 'sanasol.ws';
+  }
+}
+
+// Default domain - must be exactly 10 characters (same as hytale.com)
+const DEFAULT_NEW_DOMAIN = 'sanasol.ws';
+
+/**
+ * Patches HytaleClient and HytaleServer binaries to replace hytale.com with custom domain
+ * This allows the game to connect to a custom authentication server
+ */
+class ClientPatcher {
+  constructor() {
+    this.patchedFlag = '.patched_custom';
+  }
+
+  /**
+   * Get the target domain for patching
+   */
+  getNewDomain() {
+    const domain = getTargetDomain();
+    // Validate domain length matches original
+    if (domain.length !== ORIGINAL_DOMAIN.length) {
+      console.warn(`Warning: Domain "${domain}" length (${domain.length}) doesn't match original "${ORIGINAL_DOMAIN}" (${ORIGINAL_DOMAIN.length})`);
+      console.warn(`Using default domain: ${DEFAULT_NEW_DOMAIN}`);
+      return DEFAULT_NEW_DOMAIN;
+    }
+    return domain;
+  }
+
+  /**
+   * Convert a string to UTF-16LE bytes (how .NET stores strings)
+   */
+  stringToUtf16LE(str) {
+    const buf = Buffer.alloc(str.length * 2);
+    for (let i = 0; i < str.length; i++) {
+      buf.writeUInt16LE(str.charCodeAt(i), i * 2);
+    }
+    return buf;
+  }
+
+  /**
+   * Convert a string to UTF-8 bytes (how Java stores strings)
+   */
+  stringToUtf8(str) {
+    return Buffer.from(str, 'utf8');
+  }
+
+  /**
+   * Find all occurrences of a pattern in a buffer
+   */
+  findAllOccurrences(buffer, pattern) {
+    const positions = [];
+    let pos = 0;
+    while (pos < buffer.length) {
+      const index = buffer.indexOf(pattern, pos);
+      if (index === -1) break;
+      positions.push(index);
+      pos = index + 1;
+    }
+    return positions;
+  }
+
+  /**
+   * UTF-8 domain replacement for Java JAR files.
+   * Java stores strings in UTF-8 format in the constant pool.
+   */
+  findAndReplaceDomainUtf8(data, oldDomain, newDomain) {
+    let count = 0;
+    const result = Buffer.from(data);
+
+    const oldUtf8 = this.stringToUtf8(oldDomain);
+    const newUtf8 = this.stringToUtf8(newDomain);
+
+    // Find all occurrences of the domain
+    const positions = this.findAllOccurrences(result, oldUtf8);
+
+    for (const pos of positions) {
+      // Replace the domain
+      newUtf8.copy(result, pos);
+      count++;
+      console.log(`  Patched UTF-8 occurrence at offset 0x${pos.toString(16)}`);
+    }
+
+    return { buffer: result, count };
+  }
+
+  /**
+   * Smart domain replacement that handles both null-terminated and non-null-terminated strings.
+   * .NET AOT stores some strings in various formats:
+   * - Standard UTF-16LE (each char is 2 bytes with \x00 high byte)
+   * - Length-prefixed where last char may have metadata byte instead of \x00
+   */
+  findAndReplaceDomainSmart(data, oldDomain, newDomain) {
+    let count = 0;
+    const result = Buffer.from(data);
+
+    // Get UTF-16LE bytes without the last character
+    const oldUtf16NoLast = this.stringToUtf16LE(oldDomain.slice(0, -1));
+    const newUtf16NoLast = this.stringToUtf16LE(newDomain.slice(0, -1));
+    const oldLastChar = this.stringToUtf16LE(oldDomain.slice(-1));
+    const newLastChar = this.stringToUtf16LE(newDomain.slice(-1));
+
+    // ASCII code of last characters
+    const oldLastCharByte = oldDomain.charCodeAt(oldDomain.length - 1);
+    const newLastCharByte = newDomain.charCodeAt(newDomain.length - 1);
+
+    // Find all occurrences of the domain without the last character
+    const positions = this.findAllOccurrences(result, oldUtf16NoLast);
+
+    for (const pos of positions) {
+      // Check if we have the last character following
+      const lastCharPos = pos + oldUtf16NoLast.length;
+      if (lastCharPos + 1 > result.length) continue;
+
+      // Read the byte at last char position
+      const lastCharFirstByte = result[lastCharPos];
+
+      // Check if first byte matches the last character of old domain
+      if (lastCharFirstByte === oldLastCharByte) {
+        // Replace all but last character
+        newUtf16NoLast.copy(result, pos);
+
+        // Replace just the first byte of the last character (preserve metadata byte if any)
+        result[lastCharPos] = newLastCharByte;
+
+        // If there's a proper null byte (standard UTF-16LE), also check/preserve it
+        if (lastCharPos + 1 < result.length) {
+          const secondByte = result[lastCharPos + 1];
+          // Log what type of occurrence this is
+          if (secondByte === 0x00) {
+            console.log(`  Patched UTF-16LE occurrence at offset 0x${pos.toString(16)}`);
+          } else {
+            console.log(`  Patched length-prefixed occurrence at offset 0x${pos.toString(16)} (metadata: 0x${secondByte.toString(16)})`);
+          }
+        }
+        count++;
+      }
+    }
+
+    return { buffer: result, count };
+  }
+
+  /**
+   * Check if the client binary has already been patched
+   */
+  isPatchedAlready(clientPath) {
+    const newDomain = this.getNewDomain();
+    const patchFlagFile = clientPath + this.patchedFlag;
+    if (fs.existsSync(patchFlagFile)) {
+      try {
+        const flagData = JSON.parse(fs.readFileSync(patchFlagFile, 'utf8'));
+        // Check if patched with same target domain
+        if (flagData.targetDomain === newDomain) {
+          return true;
+        }
+      } catch (e) {
+        // Flag file corrupted, will re-patch
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Mark the client as patched
+   */
+  markAsPatched(clientPath) {
+    const newDomain = this.getNewDomain();
+    const patchFlagFile = clientPath + this.patchedFlag;
+    const flagData = {
+      patchedAt: new Date().toISOString(),
+      originalDomain: ORIGINAL_DOMAIN,
+      targetDomain: newDomain,
+      patcherVersion: '1.0.0'
+    };
+    fs.writeFileSync(patchFlagFile, JSON.stringify(flagData, null, 2));
+  }
+
+  /**
+   * Create a backup of the original client binary
+   */
+  backupClient(clientPath) {
+    const backupPath = clientPath + '.original';
+    if (!fs.existsSync(backupPath)) {
+      console.log(`  Creating backup at ${path.basename(backupPath)}`);
+      fs.copyFileSync(clientPath, backupPath);
+      return backupPath;
+    }
+    console.log('  Backup already exists');
+    return backupPath;
+  }
+
+  /**
+   * Restore the original client binary from backup
+   */
+  restoreClient(clientPath) {
+    const backupPath = clientPath + '.original';
+    if (fs.existsSync(backupPath)) {
+      fs.copyFileSync(backupPath, clientPath);
+      const patchFlagFile = clientPath + this.patchedFlag;
+      if (fs.existsSync(patchFlagFile)) {
+        fs.unlinkSync(patchFlagFile);
+      }
+      console.log('Client restored from backup');
+      return true;
+    }
+    console.log('No backup found to restore');
+    return false;
+  }
+
+  /**
+   * Patch the client binary to use the custom domain
+   * @param {string} clientPath - Path to the HytaleClient binary
+   * @param {function} progressCallback - Optional callback for progress updates
+   * @returns {object} Result object with success status and details
+   */
+  async patchClient(clientPath, progressCallback) {
+    const newDomain = this.getNewDomain();
+    console.log('=== Client Patcher ===');
+    console.log(`Target: ${clientPath}`);
+    console.log(`Replacing: ${ORIGINAL_DOMAIN} -> ${newDomain}`);
+
+    // Check if file exists
+    if (!fs.existsSync(clientPath)) {
+      const error = `Client binary not found: ${clientPath}`;
+      console.error(error);
+      return { success: false, error };
+    }
+
+    // Check if already patched
+    if (this.isPatchedAlready(clientPath)) {
+      console.log(`Client already patched for ${newDomain}, skipping`);
+      if (progressCallback) {
+        progressCallback('Client already patched', 100);
+      }
+      return { success: true, alreadyPatched: true, patchCount: 0 };
+    }
+
+    if (progressCallback) {
+      progressCallback('Preparing to patch client...', 10);
+    }
+
+    // Create backup
+    console.log('Creating backup...');
+    this.backupClient(clientPath);
+
+    if (progressCallback) {
+      progressCallback('Reading client binary...', 20);
+    }
+
+    // Read the binary
+    console.log('Reading client binary...');
+    const data = fs.readFileSync(clientPath);
+    console.log(`Binary size: ${(data.length / 1024 / 1024).toFixed(2)} MB`);
+
+    if (progressCallback) {
+      progressCallback('Patching domain references...', 50);
+    }
+
+    // Perform the domain replacement
+    console.log('Patching domain references...');
+    const { buffer: patchedData, count } = this.findAndReplaceDomainSmart(data, ORIGINAL_DOMAIN, newDomain);
+
+    if (count === 0) {
+      console.log('No occurrences of hytale.com found - binary may already be modified or has different format');
+      return { success: true, patchCount: 0, warning: 'No domain occurrences found' };
+    }
+
+    if (progressCallback) {
+      progressCallback('Writing patched binary...', 80);
+    }
+
+    // Write the patched binary
+    console.log('Writing patched binary...');
+    fs.writeFileSync(clientPath, patchedData);
+
+    // Mark as patched
+    this.markAsPatched(clientPath);
+
+    if (progressCallback) {
+      progressCallback('Patching complete', 100);
+    }
+
+    console.log(`Successfully patched ${count} occurrences`);
+    console.log('=== Patching Complete ===');
+
+    return { success: true, patchCount: count };
+  }
+
+  /**
+   * Patch the server JAR to use the custom domain
+   * JAR files are ZIP archives, so we need to extract, patch class files, and repackage
+   * @param {string} serverPath - Path to the HytaleServer.jar
+   * @param {function} progressCallback - Optional callback for progress updates
+   * @returns {object} Result object with success status and details
+   */
+  async patchServer(serverPath, progressCallback) {
+    const newDomain = this.getNewDomain();
+    console.log('=== Server Patcher ===');
+    console.log(`Target: ${serverPath}`);
+    console.log(`Replacing: ${ORIGINAL_DOMAIN} -> ${newDomain}`);
+
+    // Check if file exists
+    if (!fs.existsSync(serverPath)) {
+      const error = `Server JAR not found: ${serverPath}`;
+      console.error(error);
+      return { success: false, error };
+    }
+
+    // Check if already patched
+    if (this.isPatchedAlready(serverPath)) {
+      console.log(`Server already patched for ${newDomain}, skipping`);
+      if (progressCallback) {
+        progressCallback('Server already patched', 100);
+      }
+      return { success: true, alreadyPatched: true, patchCount: 0 };
+    }
+
+    if (progressCallback) {
+      progressCallback('Preparing to patch server...', 10);
+    }
+
+    // Create backup
+    console.log('Creating backup...');
+    this.backupClient(serverPath);
+
+    if (progressCallback) {
+      progressCallback('Extracting server JAR...', 20);
+    }
+
+    // Open the JAR file as a ZIP
+    console.log('Opening server JAR...');
+    const zip = new AdmZip(serverPath);
+    const entries = zip.getEntries();
+    console.log(`JAR contains ${entries.length} entries`);
+
+    if (progressCallback) {
+      progressCallback('Patching class files...', 40);
+    }
+
+    // Patch each entry that might contain domain strings
+    let totalCount = 0;
+    const oldUtf8 = this.stringToUtf8(ORIGINAL_DOMAIN);
+    const newUtf8 = this.stringToUtf8(newDomain);
+
+    for (const entry of entries) {
+      // Only patch class files and certain resource files
+      const name = entry.entryName;
+      if (name.endsWith('.class') || name.endsWith('.properties') ||
+          name.endsWith('.json') || name.endsWith('.xml') || name.endsWith('.yml')) {
+
+        const data = entry.getData();
+
+        // Check if this entry contains the domain
+        if (data.includes(oldUtf8)) {
+          const { buffer: patchedData, count } = this.findAndReplaceDomainUtf8(data, ORIGINAL_DOMAIN, newDomain);
+          if (count > 0) {
+            zip.updateFile(entry.entryName, patchedData);
+            console.log(`  Patched ${count} occurrences in ${name}`);
+            totalCount += count;
+          }
+        }
+      }
+    }
+
+    if (totalCount === 0) {
+      console.log('No occurrences of hytale.com found in server JAR entries');
+      return { success: true, patchCount: 0, warning: 'No domain occurrences found in JAR' };
+    }
+
+    if (progressCallback) {
+      progressCallback('Writing patched JAR...', 80);
+    }
+
+    // Write the patched JAR
+    console.log('Writing patched JAR...');
+    zip.writeZip(serverPath);
+
+    // Mark as patched
+    this.markAsPatched(serverPath);
+
+    if (progressCallback) {
+      progressCallback('Server patching complete', 100);
+    }
+
+    console.log(`Successfully patched ${totalCount} occurrences in server`);
+    console.log('=== Server Patching Complete ===');
+
+    return { success: true, patchCount: totalCount };
+  }
+
+  /**
+   * Find the client binary path based on platform
+   */
+  findClientPath(gameDir) {
+    const candidates = [];
+
+    if (process.platform === 'darwin') {
+      // macOS: Check both app bundle and direct binary
+      candidates.push(path.join(gameDir, 'Client', 'Hytale.app', 'Contents', 'MacOS', 'HytaleClient'));
+      candidates.push(path.join(gameDir, 'Client', 'HytaleClient'));
+    } else if (process.platform === 'win32') {
+      candidates.push(path.join(gameDir, 'Client', 'HytaleClient.exe'));
+    } else {
+      candidates.push(path.join(gameDir, 'Client', 'HytaleClient'));
+    }
+
+    for (const candidate of candidates) {
+      if (fs.existsSync(candidate)) {
+        return candidate;
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Find the server JAR path
+   */
+  findServerPath(gameDir) {
+    const candidates = [
+      path.join(gameDir, 'Server', 'HytaleServer.jar'),
+      path.join(gameDir, 'Server', 'server.jar')
+    ];
+
+    for (const candidate of candidates) {
+      if (fs.existsSync(candidate)) {
+        return candidate;
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Ensure both client and server are patched before launching
+   * @param {string} gameDir - Path to the game directory
+   * @param {function} progressCallback - Optional callback for progress updates
+   */
+  async ensureClientPatched(gameDir, progressCallback) {
+    const results = {
+      client: null,
+      server: null,
+      success: true
+    };
+
+    // Patch client
+    const clientPath = this.findClientPath(gameDir);
+    if (clientPath) {
+      if (progressCallback) {
+        progressCallback('Patching client binary...', 10);
+      }
+      results.client = await this.patchClient(clientPath, (msg, pct) => {
+        if (progressCallback) {
+          progressCallback(`Client: ${msg}`, pct ? pct / 2 : null);
+        }
+      });
+    } else {
+      console.warn('Could not find HytaleClient binary');
+      results.client = { success: false, error: 'Client binary not found' };
+    }
+
+    // Patch server
+    const serverPath = this.findServerPath(gameDir);
+    if (serverPath) {
+      if (progressCallback) {
+        progressCallback('Patching server JAR...', 50);
+      }
+      results.server = await this.patchServer(serverPath, (msg, pct) => {
+        if (progressCallback) {
+          progressCallback(`Server: ${msg}`, pct ? 50 + pct / 2 : null);
+        }
+      });
+    } else {
+      console.warn('Could not find HytaleServer.jar');
+      results.server = { success: false, error: 'Server JAR not found' };
+    }
+
+    // Calculate overall success
+    results.success = (results.client && results.client.success) || (results.server && results.server.success);
+    results.alreadyPatched = (results.client && results.client.alreadyPatched) && (results.server && results.server.alreadyPatched);
+    results.patchCount = (results.client ? results.client.patchCount || 0 : 0) + (results.server ? results.server.patchCount || 0 : 0);
+
+    if (progressCallback) {
+      progressCallback('Patching complete', 100);
+    }
+
+    return results;
+  }
+}
+
+// Export singleton instance
+module.exports = new ClientPatcher();