From b459a1dbd43af44ce20fbf61ed98331a77dd6987 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tam=C3=A1s=20Papp?= <pappt1216+github@gmail.com>
Date: Wed, 18 Jun 2025 20:32:35 +0200
Subject: [PATCH] Support new login payload on Client

---
 src/client.js      | 38 +++++++++++++++++++++++++++++++-------
 src/client/auth.js |  7 +++++++
 2 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/src/client.js b/src/client.js
index 472a777..7c05b39 100644
--- a/src/client.js
+++ b/src/client.js
@@ -141,19 +141,43 @@ class Client extends Connection {
     this.status = ClientStatus.Authenticating
     this.createClientChain(null, this.options.offline)
 
-    const chain = [
-      this.clientIdentityChain, // JWT we generated for auth
-      ...this.accessToken // Mojang + Xbox JWT from auth
-    ]
+    const useNewLogin = true // TODO: mcdata feature
+    let encodedLoginPayload
 
-    const encodedChain = JSON.stringify({ chain })
+    if (useNewLogin) {
+      const authType = this.options.offline
+        ? auth.AuthenticationType.SelfSigned
+        : auth.AuthenticationType.Full
 
-    debug('Auth chain', chain)
+      // TODO: implement the new login payload (Token field)
+      // Send the legacy token chain for now
+      const chain = [
+        this.clientIdentityChain,
+        ...this.accessToken
+      ]
+
+      encodedLoginPayload = JSON.stringify({
+        AuthenticationType: authType,
+        Token: '',
+        Certificate: JSON.stringify({ chain }), // Deprecated legacy certificate chain
+      })
+
+      debug('Login payload', encodedLoginPayload)
+    } else {
+      const chain = [
+        this.clientIdentityChain, // JWT we generated for auth
+        ...this.accessToken // Mojang + Xbox JWT from auth
+      ]
+
+      encodedLoginPayload = JSON.stringify({ chain })
+
+      debug('Auth chain', chain)
+    }
 
     this.write('login', {
       protocol_version: this.options.protocolVersion,
       tokens: {
-        identity: encodedChain,
+        identity: encodedLoginPayload,
         client: this.clientUserChain
       }
     })
diff --git a/src/client/auth.js b/src/client/auth.js
index 7a07d83..3703379 100644
--- a/src/client/auth.js
+++ b/src/client/auth.js
@@ -5,6 +5,12 @@ const debug = require('debug')('minecraft-protocol')
 const { uuidFrom } = require('../datatypes/util')
 const { RealmAPI } = require('prismarine-realms')
 
+const AuthenticationType = {
+  Full: 0, // The player's own token
+  Guest: 1, // Split screen sessions, the player is using the host's token
+  SelfSigned: 2, // Not authenticated
+}
+
 function validateOptions (options) {
   if (!options.profilesFolder) {
     options.profilesFolder = path.join(minecraftFolderPath, 'nmp-cache')
@@ -113,6 +119,7 @@ function postAuthenticate (client, profile, chains) {
 }
 
 module.exports = {
+  AuthenticationType,
   createOfflineSession,
   authenticate,
   realmAuthenticate