Obtain IP adress for MDNS automatically

tutorials/udp/mdns-client/main.c

@@ -15,7 +15,6 @@ static void mdns_ev_handler(struct mg_connection *c, int ev, void *ev_data) {
 }
 
 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
@@ -24,10 +23,6 @@ int main(void) {
   // Desired name must NOT have any dots in it, nor a domain
   c = mg_mdns_listen(&mgr, mdns_ev_handler, "Mongoose");  // Start mDNS server
   if (c == NULL) return 1;
-  // 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));
   if (!mg_mdns_query(c, s_theone, MG_DNS_RTYPE_A)) return 1;
 
   for (;;) mg_mgr_poll(&mgr, 1000);  // Event loop

tutorials/udp/mdns-sd-server/main.c

@@ -15,7 +15,10 @@
 // Desired name must NOT have any dots in it, nor a domain
 #define MDNS_NAME "mongoose-device"
 #define WEB_SERVER_ADDR "http://0.0.0.0:8000"  // port is hardcoded below
-#define RESPONSE_IP "192.168.69.11"
+
+// When not using our built-in TCP/IP stack, Mongoose responds with the address
+// of the interface in which the request came in. If, for some reason, you want
+// to use some other address, fill req->addr. See: mdns-client advanced example
 
 #ifdef ADVANCED_EXAMPLE
 // A TXT record data containing JSON, if actually needed.
@@ -80,7 +83,8 @@ static void mdns_ev_handler(struct mg_connection *c, int ev, void *ev_data) {
                req->rr->atype == MG_DNS_RTYPE_TXT) {
       // Mongoose already checked the host name for us, otherwise we need to do
       // that ourselves first, then check for service name in db
-      struct mg_dnssd_record *r = (struct mg_dnssd_record *) dnssd_lookup(req->reqname);
+      struct mg_dnssd_record *r =
+          (struct mg_dnssd_record *) dnssd_lookup(req->reqname);
       if (r == NULL) return;
       req->r = r;
       req->is_resp = true;
@@ -107,17 +111,12 @@ static void http_ev_handler(struct mg_connection *c, int ev, void *ev_data) {
 int main(void) {
   struct mg_mgr mgr;
   static struct mg_connection *c;
-  uint32_t response_ip = inet_addr(RESPONSE_IP);
 
   mg_log_set(MG_LL_DEBUG);  // Set log level
   mg_mgr_init(&mgr);        // Initialise event manager
 
   c = mg_mdns_listen(&mgr, mdns_ev_handler, MDNS_NAME);
   if (c == NULL) return 1;
-  // 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));
 
   mg_http_listen(&mgr, WEB_SERVER_ADDR, http_ev_handler, NULL);
 

tutorials/udp/mdns-server/main.c

@@ -3,23 +3,45 @@
 
 #include "mongoose.h"
 
+#ifdef ADVANCED_EXAMPLE
+static void mdns_ev_handler(struct mg_connection *c, int ev, void *ev_data);
+#endif
+
 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
+#ifndef ADVANCED_EXAMPLE
   c = mg_mdns_listen(&mgr, NULL, "Mongoose");  // Start mDNS server
+#else
+  c = mg_mdns_listen(&mgr, mdns_ev_handler, "Mongoose");  // Start mDNS server
+#endif
   if (c == NULL) return 1;
-  // 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;
 }
+
+// When not using our built-in TCP/IP stack, Mongoose responds with the address
+// of the interface in which the request came in. If, for some reason, you want
+// to use some other address, catch the MG_EV_MDNS_REQ event for MG_DNS_RTYPE_A
+// requests, and fill your desired address
+#ifdef ADVANCED_EXAMPLE
+static void mdns_ev_handler(struct mg_connection *c, int ev, void *ev_data) {
+  if (ev == MG_EV_MDNS_REQ) {
+    struct mg_mdns_req *req = (struct mg_mdns_req *) ev_data;
+    if (req->rr->atype == MG_DNS_RTYPE_A) {
+      struct mg_addr myaddr;
+      memset(&myaddr, 0, sizeof(myaddr));
+      myaddr.addr.ip4 = MG_IPV4(1, 2, 3, 4);
+      req->addr = &myaddr;
+    }
+  }
+  (void) c;
+}
+#endif