From 7b9b312dcd92f2f570f4f018149d13869d69a5c5 Mon Sep 17 00:00:00 2001
From: mrambossek <git@rambossek.at>
Date: Fri, 31 Jul 2026 22:13:13 +0200
Subject: [PATCH] beacon: own-IP filter (shared-LAN fix) +
 wireless-debugging-off warning
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Live multi-device test exposed two things:
- On a shared LAN, NsdManager discovers EVERY device's
  _adb-tls-connect._tcp advertisement, so a phone reported the tablet's
  port for its own IP (crossed). Now only accept the resolved service
  whose host matches this device's own wlan0 IP.
- When Wireless debugging is turned off, adbd drops its mDNS
  advertisement (onServiceLost) — the app now says so plainly in the
  status line and the ongoing notification ("Wireless debugging appears
  OFF — re-enable it"), instead of a vague "waiting".

Verified with phone + tablet on the same LAN: correct per-device ports,
both auto-connected.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
---
 .../app/echo_lot/adbbeacon/BeaconService.kt   | 26 ++++++++++++++++---
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/echolot-app/adb-beacon/src/main/kotlin/app/echo_lot/adbbeacon/BeaconService.kt b/echolot-app/adb-beacon/src/main/kotlin/app/echo_lot/adbbeacon/BeaconService.kt
index 48395f6..dfd2eb7 100644
--- a/echolot-app/adb-beacon/src/main/kotlin/app/echo_lot/adbbeacon/BeaconService.kt
+++ b/echolot-app/adb-beacon/src/main/kotlin/app/echo_lot/adbbeacon/BeaconService.kt
@@ -62,7 +62,13 @@ class BeaconService : Service() {
             override fun onStopDiscoveryFailed(t: String?, code: Int) {}
             override fun onDiscoveryStarted(t: String?) {}
             override fun onDiscoveryStopped(t: String?) {}
-            override fun onServiceLost(s: NsdServiceInfo?) { currentPort = -1 }
+            override fun onServiceLost(s: NsdServiceInfo?) {
+                // adbd stops advertising when Wireless debugging is turned off.
+                currentPort = -1
+                val warn = "⚠ Wireless debugging appears OFF (adb mDNS service gone) — re-enable it"
+                Status.set(warn)
+                updateNotification(warn)
+            }
             override fun onServiceFound(s: NsdServiceInfo?) {
                 if (s == null) return
                 resolve(s)
@@ -79,8 +85,14 @@ class BeaconService : Service() {
         nsd.resolveService(info, object : NsdManager.ResolveListener {
             override fun onResolveFailed(s: NsdServiceInfo?, code: Int) {}
             override fun onServiceResolved(s: NsdServiceInfo?) {
-                val port = s?.port ?: return
-                currentPort = port
+                s ?: return
+                // On a shared LAN, NsdManager discovers EVERY device's adb
+                // advertisement — accept only the one whose host is THIS device's
+                // own IP, else we'd report a neighbour's port for our IP.
+                val host = s.host?.hostAddress
+                val mine = wifiIpv4()
+                if (host != null && mine != null && host != mine) return
+                currentPort = s.port
                 scope.launch { report() }
             }
         })
@@ -89,7 +101,13 @@ class BeaconService : Service() {
     private fun report() {
         val ip = wifiIpv4() ?: run { Status.set("no wlan0 IPv4 (is wifi up?)"); return }
         val port = currentPort
-        if (port <= 0) { Status.set("$ip — waiting for wireless-debug port"); return }
+        if (port <= 0) {
+            // No adb advertisement: either discovery hasn't landed yet, or (usually) Wireless
+            // debugging is off. Say so plainly.
+            val warn = "⚠ $ip — no wireless-debug port. Is Wireless debugging ON?"
+            Status.set(warn); updateNotification(warn)
+            return
+        }
         val device = android.os.Build.MODEL.replace(Regex("[^A-Za-z0-9_.-]"), "_")
         val body = """{"device":"$device","ip":"$ip","port":$port}"""
         // Send over a VALIDATED internet network — the wireless-debug wifi is often a restricted