fix: NCD UAF, conn_mgr invite protocol, node_id derivation, link reuse

node_conn_direct:
- ncd_init_cb: skip UP when links_up==0, ncd_up_cb delivers when link comes up
- close/force_close: handle_count safety checks, callback clearing
- open/open_node case 2: create links on reused dead conn
- ncd_create_links: skip duplicate link on same conn (stale->etcp==conn)
- set_callback: optional callback change on live handle

conn_mgr:
- cm_ncd_callback: DOWN only delivers event (handle stays alive)
- cm_ncd_callback: TIMEOUT force_close BEFORE cm_deliver_event
- cm_deliver_event: read handle fields to locals before callback (reentrany-safe)
- INVITE_INFO_REQ/RESP: add duplicate cmd byte for direct-send protocol
- cm_handle_invite_info_resp: search invite by group_id in channel conn_mgr

Android:
- node_id computed by sc_derive_node_id_from_pubkey in C, not Kotlin
- utun_bridge_join_channel: recompute node_id, log mismatch
- invite_link_c: compute nodeId from pubkey via sc_derive_node_id_from_pubkey
- NativeLib.deriveNodeId, InviteLink.kt uses C function

tools/chatgui-android/app/src/main/java/com/utun/chat/data/InviteLink.kt

@@ -62,15 +62,6 @@ data class InviteData(
 object InviteLink {
     private const val PREFIX = "utun://"
 
-    fun deriveNodeId(pubkey: ByteArray): Long {
-        val md = MessageDigest.getInstance("SHA-256")
-        val hash = md.digest(pubkey)
-        var id = 0L
-        for (i in 0 until 8)
-            id = (id shl 8) or (hash[i].toLong() and 0xFF)
-        return id and 0x7FFFFFFFFFFFFFFFL
-    }
-
     fun decode(link: String): InviteData? {
         LogManager.addLog("DEBUG", "INVITE", "decode: ${link.take(80)}")
         if (!link.startsWith(PREFIX)) {
@@ -140,7 +131,7 @@ object InviteLink {
         }
 
         if (pubkey == null || pubkey.size != INVITE_PUBKEY_SIZE) return null
-        val nodeId = deriveNodeId(pubkey)
+        val nodeId = NativeLib.deriveNodeId(pubkey)
         val pkHex = pubkey.take(8).joinToString("") { "%02x".format(it) }
         LogManager.addLog("INFO", "INVITE", "decode: ch=0x%016x node=0x%016x pk=%s... addrs=%d".format(
             chId, nodeId, pkHex, addrs.size))

tools/chatgui-android/app/src/main/java/com/utun/chat/data/NativeLib.kt

@@ -7,7 +7,6 @@ interface ChatEventCallback {
 }
 
 object NativeLib {
-    private var running = false
 
     init {
         System.loadLibrary("utun")
@@ -24,16 +23,13 @@ object NativeLib {
 
     /** Start full uTun instance from INI config text */
     fun start(configText: String): Boolean {
-        if (running) return true
-        val ok = nativeStart(configText)
-        if (ok) running = true
-        return ok
+        if (isReady()) return true
+        return nativeStart(configText)
     }
 
     fun stop() {
-        if (!running) return
+        if (!isReady()) return
         nativeStop()
-        running = false
     }
 
     fun setEventCallback(cb: ChatEventCallback) {
@@ -42,16 +38,13 @@ object NativeLib {
         })
     }
 
-    fun destroy() {
-        nativeDestroy()
-        running = false
-    }
+    fun destroy() { nativeDestroy() }
 
     fun restart(dbPath: String, controlPort: Int, configText: String): Boolean {
         return nativeRestart(configText)
     }
 
-    fun isReady(): Boolean = running
+    fun isReady(): Boolean = nativeIsRunning()
 
     fun getMyNodeId(): Long = nativeGetMyNodeId()
 
@@ -66,6 +59,7 @@ object NativeLib {
         nativeJoinChannel(channelId, nodeId, pubkey, addrs, addrCount)
         LogManager.addLog("INFO", "JNI", "joinChannel: native returned")
     }
+    fun deriveNodeId(pubkey: ByteArray): Long = nativeDeriveNodeId(pubkey)
     fun connectChannel(channelId: String) { nativeConnectChannel(channelId) }
     fun getChannels(): String = nativeGetChannels() ?: "[]"
     fun getMessages(channelId: String, limit: Int = 50): String = nativeGetMessages(channelId, limit) ?: "[]"
@@ -124,6 +118,7 @@ object NativeLib {
     private external fun nativeCreateChannel(name: String, channelId: String)
     private external fun nativeConnectNode(address: String, port: Int, pubkeyHex: String)
     private external fun nativeJoinChannel(channelId: Long, nodeId: Long, pubkey: ByteArray, addrs: ByteArray, addrCount: Int)
+    private external fun nativeDeriveNodeId(pubkey: ByteArray): Long
     private external fun nativeConnectChannel(channelId: String)
     private external fun nativeGetChannels(): String?
     private external fun nativeGetMessages(channelId: String, limit: Int): String?
@@ -138,6 +133,7 @@ object NativeLib {
     private external fun nativeRestart(configText: String): Boolean
     private external fun nativePing()
     private external fun nativeIsResponsive(): Boolean
+    private external fun nativeIsRunning(): Boolean
 
     /* ── Channel members JNI ── */
     private external fun nativeGetChannelMembers(channelId: String): String?

tools/chatgui-android/app/src/main/java/com/utun/chat/viewmodel/ChatViewModel.kt

@@ -95,7 +95,7 @@ class ChatViewModel : ViewModel() {
         viewModelScope.launch {
             while (isActive) {
                 delay(3000)
-                if (!dbReady || !NativeLib.isReady()) continue
+                if (!dbReady || !NativeLib.isReady()) { _isStuck.value = true; continue }
                 NativeLib.ping()
                 delay(100)
                 _isStuck.value = !NativeLib.isResponsive()

tools/chatgui-android/jni_bridge/android_jni_bridge.c

@@ -22,6 +22,7 @@
 #include "../../../src/utun_instance.h"
 #include "../../../src/transport_layer/etcp.h"
 #include "../../../src/transport_layer/etcp_connections.h"
+#include "../../../src/transport_layer/secure_channel.h"
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -215,14 +216,18 @@ void utun_bridge_join_channel(uint64_t channel_id, uint64_t node_id,
                                 const uint8_t* pubkey_bin,
                                 const uint8_t* addrs_data, int addr_count,
                                 int addrs_data_len) {
+    uint64_t real_node_id = sc_derive_node_id_from_pubkey(pubkey_bin);
+    if (real_node_id != node_id)
+        bridge_log(BLEV_WARN, "join: node_id Kotlin=0x%016llx != C=0x%016llx — using C value",
+                   (unsigned long long)node_id, (unsigned long long)real_node_id);
     bridge_log(BLEV_INFO, "join ch=%llu node=0x%016llx addrs=%d len=%d",
-               (unsigned long long)channel_id, (unsigned long long)node_id, addr_count, addrs_data_len);
+               (unsigned long long)channel_id, (unsigned long long)real_node_id, addr_count, addrs_data_len);
     if (!pubkey_bin || !addrs_data || addr_count <= 0) {
         bridge_log(BLEV_ERROR, "join invalid args");
         utun_bridge_event(6, "{\"node_id\":0,\"result\":-7}");  /* CHAT_EVT_CONNECT_RESULT */
         return;
     }
-    chat_sync_connect_from_invite(channel_id, node_id, pubkey_bin, addrs_data, addr_count, addrs_data_len);
+    chat_sync_connect_from_invite(channel_id, real_node_id, pubkey_bin, addrs_data, addr_count, addrs_data_len);
 }
 
 void utun_bridge_connect_channel(const char* channel_id) {
@@ -1131,6 +1136,20 @@ JNIEXPORT void JNICALL Java_com_utun_chat_data_NativeLib_nativeJoinChannel(
     (*env)->ReleaseByteArrayElements(env, pubkey, (jbyte*)pk, JNI_ABORT);
 }
 
+/* ── nativeDeriveNodeId ── */
+
+JNIEXPORT jlong JNICALL Java_com_utun_chat_data_NativeLib_nativeDeriveNodeId(
+    JNIEnv* env, jobject thiz, jbyteArray pubkey) {
+    (void)thiz;
+    if (!pubkey) return 0;
+    jsize pk_len = (*env)->GetArrayLength(env, pubkey);
+    if (pk_len < 32) return 0;
+    uint8_t* pk = (uint8_t*)(*env)->GetByteArrayElements(env, pubkey, NULL);
+    uint64_t node_id = sc_derive_node_id_from_pubkey(pk);
+    (*env)->ReleaseByteArrayElements(env, pubkey, (jbyte*)pk, JNI_ABORT);
+    return (jlong)node_id;
+}
+
 /* ── nativeSetEventCallback(eventCb) ── */
 
 JNIEXPORT void JNICALL Java_com_utun_chat_data_NativeLib_nativeSetEventCallback(
@@ -1233,6 +1252,12 @@ JNIEXPORT jboolean JNICALL Java_com_utun_chat_data_NativeLib_nativeIsResponsive(
     return utun_bridge_is_responsive() ? JNI_TRUE : JNI_FALSE;
 }
 
+JNIEXPORT jboolean JNICALL Java_com_utun_chat_data_NativeLib_nativeIsRunning(
+    JNIEnv* env, jobject thiz) {
+    (void)env; (void)thiz;
+    return instance_lite_is_running() ? JNI_TRUE : JNI_FALSE;
+}
+
 JNIEXPORT void JNICALL Java_com_utun_chat_data_NativeLib_nativePing(
     JNIEnv* env, jobject thiz) {
     (void)env; (void)thiz;

tools/chatgui-android/libutun_lite/instance_lite.c

@@ -309,6 +309,7 @@ static void restart_trampoline(void* arg) {
     if (!new_config) {
         IL_LOGE("restart: parse_config failed");
         g_running = 0;
+        g_inst = NULL;
         return;
     }
 
@@ -342,12 +343,14 @@ static void restart_trampoline(void* arg) {
     } else {
         IL_LOGE("restart: SQLite reopen failed rc=%d", rc);
         g_running = 0;
+        g_inst = NULL;
         return;
     }
 
     if (utun_instance_init(g_inst) != 0) {
         IL_LOGE("restart: utun_instance_init failed");
         g_running = 0;
+        g_inst = NULL;
         return;
     }
 
@@ -360,7 +363,13 @@ static void restart_trampoline(void* arg) {
 }
 
 void instance_lite_restart(const char* new_config_text) {
-    if (!g_ua || !g_inst || !new_config_text) return;
+    if (!new_config_text) return;
+    if (!g_ua || !g_inst || !g_running) {
+        IL_LOGI("restart: instance dead, doing hard restart via stop+start");
+        if (g_inst) instance_lite_stop();
+        instance_lite_start(new_config_text);
+        return;
+    }
     IL_LOGI("restart: posting to uasync");
     char* copy = u_strdup(new_config_text);
     if (!copy) return;
@@ -384,11 +393,13 @@ void instance_lite_ping(void) {
 }
 
 int instance_lite_is_responsive(void) {
+    if (!g_ua || !g_inst || !g_running) return 0;
+    if (g_ping_id == 0) return 0;
     return (g_pong_id == g_ping_id) ? 1 : 0;
 }
 
 int instance_lite_is_running(void) {
-    return g_inst != NULL ? 1 : 0;
+    return (g_inst != NULL && g_running) ? 1 : 0;
 }
 
 struct UASYNC* instance_lite_get_uasync(void) {

tools/chatgui-android/libutun_lite/invite_link_c.c

@@ -3,6 +3,8 @@
 #include <stdlib.h>
 #include <stdio.h>
 
+#include "../../../src/transport_layer/secure_channel.h"
+
 #define INVITE_PREFIX     "utun://"
 #define INVITE_PREFIX_LEN 7
 
@@ -81,7 +83,6 @@ int invite_link_decode(const char* link, size_t link_len, struct InviteDataC* ou
     for (int i = 0; i < 8; i++)
         chId = (chId << 8) | raw[off++];
     out->channelId = chId;
-    out->nodeId = 0;
     memset(out->pubkey, 0, INVITE_PUBKEY_SIZE);
     out->addrCount = 0;
 
@@ -99,6 +100,7 @@ int invite_link_decode(const char* link, size_t link_len, struct InviteDataC* ou
         }
         if (first_block) {
             memcpy(out->pubkey, raw + off, INVITE_PUBKEY_SIZE);
+            out->nodeId = sc_derive_node_id_from_pubkey(out->pubkey);
             first_block = 0;
         }
         off += 32;