Added MDNS and driver support for multicast

tutorials/udp/mdns-server/main.c

@@ -0,0 +1,24 @@
+// Copyright (c) 2022 Cesanta Software Limited
+// All rights reserved
+
+#include "mongoose.h"
+
+int main(void) {
+  uint32_t response_ip = inet_addr("192.168.69.11");
+  struct mg_mgr mgr;
+  static struct mg_connection *c;
+  mg_log_set(MG_LL_DEBUG);  // Set log level
+  mg_mgr_init(&mgr);        // Initialise event manager
+
+  // Desired name must NOT have any dots in it, nor a domain
+  c = mg_mdns_listen(&mgr, "Mongoose");  // Start mDNS server
+  // if not using our built-in TCP/IP stack, pass the IP address you want to
+  // use as a response, this depends on your underlying TCP/IP stack and number
+  // of interfaces available
+  memcpy(c->data, &response_ip, sizeof(response_ip));
+
+  for (;;) mg_mgr_poll(&mgr, 1000);  // Event loop
+
+  mg_mgr_free(&mgr);
+  return 0;
+}