From be5f0a9ade316b7bda9feeb668e6b80613f88e72 Mon Sep 17 00:00:00 2001
From: Ben Meadors <benmmeadors@gmail.com>
Date: Wed, 4 Feb 2026 11:15:38 -0600
Subject: [PATCH] Implement UDP multicast handler start/stop to ensure proper
 lifecycle (#9524)

* Implement UDP multicast handler start/stop to ensure proper lifecycle

* Add close method to AsyncUDP and improve UDP multicast handler lifecycle management

* Guard portduino
---
 src/mesh/udp/UdpMulticastHandler.h | 25 +++++++++++++++++++++++--
 src/mesh/wifi/WiFiAPClient.cpp     | 10 ++++++++++
 src/platform/nrf52/AsyncUDP.cpp    |  7 +++++++
 src/platform/nrf52/AsyncUDP.h      |  1 +
 4 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/src/mesh/udp/UdpMulticastHandler.h b/src/mesh/udp/UdpMulticastHandler.h
index 2df8686a3..d79b63ceb 100644
--- a/src/mesh/udp/UdpMulticastHandler.h
+++ b/src/mesh/udp/UdpMulticastHandler.h
@@ -22,10 +22,14 @@
 class UdpMulticastHandler final
 {
   public:
-    UdpMulticastHandler() { udpIpAddress = IPAddress(224, 0, 0, 69); }
+    UdpMulticastHandler() : isRunning(false) { udpIpAddress = IPAddress(224, 0, 0, 69); }
 
     void start()
     {
+        if (isRunning) {
+            LOG_DEBUG("UDP multicast already running");
+            return;
+        }
         if (udp.listenMulticast(udpIpAddress, UDP_MULTICAST_DEFAUL_PORT, 64)) {
 #if defined(ARCH_NRF52) || defined(ARCH_PORTDUINO)
             LOG_DEBUG("UDP Listening on IP: %u.%u.%u.%u:%u", udpIpAddress[0], udpIpAddress[1], udpIpAddress[2], udpIpAddress[3],
@@ -34,13 +38,29 @@ class UdpMulticastHandler final
             LOG_DEBUG("UDP Listening on IP: %s", WiFi.localIP().toString().c_str());
 #endif
             udp.onPacket([this](AsyncUDPPacket packet) { onReceive(packet); });
+            isRunning = true;
         } else {
             LOG_DEBUG("Failed to listen on UDP");
         }
     }
 
+    void stop()
+    {
+        if (!isRunning) {
+            return;
+        }
+        LOG_DEBUG("Stopping UDP multicast");
+#if defined(ARCH_ESP32) || defined(ARCH_NRF52)
+        udp.close();
+#endif
+        isRunning = false;
+    }
+
     void onReceive(AsyncUDPPacket packet)
     {
+        if (!isRunning) {
+            return;
+        }
         size_t packetLength = packet.length();
 #if defined(ARCH_NRF52)
         IPAddress ip = packet.remoteIP();
@@ -67,7 +87,7 @@ class UdpMulticastHandler final
 
     bool onSend(const meshtastic_MeshPacket *mp)
     {
-        if (!mp || !udp) {
+        if (!isRunning || !mp || !udp) {
             return false;
         }
 #if defined(ARCH_NRF52)
@@ -92,5 +112,6 @@ class UdpMulticastHandler final
   private:
     IPAddress udpIpAddress;
     AsyncUDP udp;
+    bool isRunning;
 };
 #endif // HAS_UDP_MULTICAST
\ No newline at end of file
diff --git a/src/mesh/wifi/WiFiAPClient.cpp b/src/mesh/wifi/WiFiAPClient.cpp
index a95dfa58f..5d05c7fc6 100644
--- a/src/mesh/wifi/WiFiAPClient.cpp
+++ b/src/mesh/wifi/WiFiAPClient.cpp
@@ -391,6 +391,11 @@ static void WiFiEvent(WiFiEvent_t event)
         LOG_INFO("Disconnected from WiFi access point");
 #ifdef WIFI_LED
         digitalWrite(WIFI_LED, LOW);
+#endif
+#if HAS_UDP_MULTICAST
+        if (udpHandler) {
+            udpHandler->stop();
+        }
 #endif
         if (!isReconnecting) {
             WiFi.disconnect(false, true);
@@ -417,6 +422,11 @@ static void WiFiEvent(WiFiEvent_t event)
         break;
     case ARDUINO_EVENT_WIFI_STA_LOST_IP:
         LOG_INFO("Lost IP address and IP address is reset to 0");
+#if HAS_UDP_MULTICAST
+        if (udpHandler) {
+            udpHandler->stop();
+        }
+#endif
         if (!isReconnecting) {
             WiFi.disconnect(false, true);
             syslog.disable();
diff --git a/src/platform/nrf52/AsyncUDP.cpp b/src/platform/nrf52/AsyncUDP.cpp
index 836fb1307..d119ffddb 100644
--- a/src/platform/nrf52/AsyncUDP.cpp
+++ b/src/platform/nrf52/AsyncUDP.cpp
@@ -36,6 +36,13 @@ bool AsyncUDP::writeTo(const uint8_t *data, size_t len, IPAddress ip, uint16_t p
     return udp.endPacket();
 }
 
+void AsyncUDP::close()
+{
+    udp.stop();
+    localPort = 0;
+    _onPacket = nullptr;
+}
+
 // AsyncUDPPacket
 AsyncUDPPacket::AsyncUDPPacket(EthernetUDP &source) : _udp(source), _remoteIP(source.remoteIP()), _remotePort(source.remotePort())
 {
diff --git a/src/platform/nrf52/AsyncUDP.h b/src/platform/nrf52/AsyncUDP.h
index e2b406ba9..718277309 100644
--- a/src/platform/nrf52/AsyncUDP.h
+++ b/src/platform/nrf52/AsyncUDP.h
@@ -22,6 +22,7 @@ class AsyncUDP : public Print, private concurrency::OSThread
 
     bool listenMulticast(IPAddress multicastIP, uint16_t port, uint8_t ttl = 64);
     bool writeTo(const uint8_t *data, size_t len, IPAddress ip, uint16_t port);
+    void close();
 
     size_t write(uint8_t b) override;
     size_t write(const uint8_t *data, size_t len) override;