Add UDP multicast support on linux.

We tested it an it works.

This is really hacky to say the least.

arch/portduino/portduino.ini

@@ -1,6 +1,6 @@
 ; The Portduino based 'native' environment. Currently supported on Linux targets with real LoRa hardware (or simulated).
 [portduino_base]
-platform = https://github.com/meshtastic/platform-native.git#562d189828f09fbf4c4093b3c0104bae9d8e9ff9
+platform = symlink://../platform-native
 framework = arduino
 
 build_src_filter = 
@@ -34,10 +34,12 @@ build_flags =
   -Isrc/platform/portduino
   -DRADIOLIB_EEPROM_UNSUPPORTED
   -DPORTDUINO_LINUX_HARDWARE
+  -DHAS_UDP_MULTICAST
   -lpthread
   -lstdc++fs
   -lbluetooth
   -lgpiod
   -lyaml-cpp
   -li2c
+  -luv
   -std=c++17

src/main.cpp

@@ -822,6 +822,10 @@ void setup()
 #ifdef HAS_UDP_MULTICAST
     LOG_DEBUG("Start multicast thread");
     udpThread = new UdpMulticastThread();
+#ifdef ARCH_PORTDUINO
+    // FIXME: portduino does not ever call onNetworkConnected so call it here because I don't know what happen if I call onNetworkConnected there
+    udpThread->start();
+#endif
 #endif
     service = new MeshService();
     service->init();

src/mesh/udp/UdpMulticastThread.h

@@ -23,7 +23,12 @@ class UdpMulticastThread : public concurrency::OSThread
     void start()
     {
         if (udp.listenMulticast(udpIpAddress, UDP_MULTICAST_DEFAUL_PORT)) {
-            LOG_DEBUG("UDP Listening on IP: %s", WiFi.localIP().toString().c_str());
+            #if !defined(ARCH_PORTDUINO)
+                // FIXME(PORTDUINO): arduino lacks IPAddress::toString()
+                LOG_DEBUG("UDP Listening on IP: %s", WiFi.localIP().toString().c_str());
+            #else
+                LOG_DEBUG("UDP Listening");
+            #endif
             udp.onPacket([this](AsyncUDPPacket packet) { onReceive(packet); });
         } else {
             LOG_DEBUG("Failed to listen on UDP");
@@ -33,7 +38,10 @@ class UdpMulticastThread : public concurrency::OSThread
     void onReceive(AsyncUDPPacket packet)
     {
         size_t packetLength = packet.length();
-        LOG_DEBUG("UDP broadcast from: %s, len=%u", packet.remoteIP().toString().c_str(), packetLength);
+        #ifndef ARCH_PORTDUINO
+            // FIXME(PORTDUINO): arduino lacks IPAddress::toString()
+            LOG_DEBUG("UDP broadcast from: %s, len=%u", packet.remoteIP().toString().c_str(), packetLength);
+        #endif
         meshtastic_MeshPacket mp;
         LOG_DEBUG("Decoding MeshPacket from UDP len=%u", packetLength);
         bool isPacketDecoded = pb_decode_from_bytes(packet.data(), packetLength, &meshtastic_MeshPacket_msg, &mp);
@@ -48,9 +56,14 @@ class UdpMulticastThread : public concurrency::OSThread
 
     bool onSend(const meshtastic_MeshPacket *mp)
     {
-        if (!mp || WiFi.status() != WL_CONNECTED) {
+        if (!mp || !udp) {
             return false;
         }
+        #if !defined(ARCH_PORTDUINO)
+        if (WiFi.status() != WL_CONNECTED) {
+            return false;
+        }
+        #endif
         LOG_DEBUG("Broadcasting packet over UDP (id=%u)", mp->id);
         uint8_t buffer[meshtastic_MeshPacket_size];
         size_t encodedLength = pb_encode_to_bytes(buffer, sizeof(buffer), &meshtastic_MeshPacket_msg, mp);