mdns: Don't pass mdns_recv return to the announce callback

mdns_recv returns -1 on error and 0 on success, but we don't invoke the
callback when mdns_recv fails, so we were passing a useless parameter
always equal to 0.

examples/announce.c

@@ -42,7 +42,7 @@ static bool stop(void *cbarg)
         return (sigflag ? true : false);
 }
 
-static void callback(void *cbarg, int r, const struct sockaddr *mdns_ip, const char* service)
+static void callback(void *cbarg, const struct sockaddr *mdns_ip, const char* service)
 {
         if ( service != NULL && strcmp( service, "_googlecast._tcp.local" ) )
             return;

include/microdns/microdns.h

@@ -83,7 +83,6 @@ typedef void (*mdns_listen_callback)(void*, int, const struct rr_entry *);
  * @brief mdns_announce_callback Will be invoked for each received question
  *
  * @param cookie The pointer provided as last parameter to mdns_serve
- * @param r The mdns_recv result
  * @param addr The address for which a probe was received
  * @param service The service being probed
  *
@@ -95,7 +94,7 @@ typedef void (*mdns_listen_callback)(void*, int, const struct rr_entry *);
  * service, so that the application can announce itself as it sees fit (for
  * instance it can announce both an A and AAAA records)
  */
-typedef void (*mdns_announce_callback)(void* cookie, int r,
+typedef void (*mdns_announce_callback)(void* cookie,
                                        const struct sockaddr *addr,
                                        const char* service);
 

src/mdns.c

@@ -824,7 +824,7 @@ mdns_serve(struct mdns_ctx *ctx, mdns_stop_func stop, void *p_cookie)
         /* Send the initial announce (RFC 6762 §8.3) */
         for (svc = ctx->services; svc; svc = svc->next) {
             for ( size_t i = 0; i < ctx->nb_conns; ++i ) {
-                svc->announce_callback(svc->p_cookie, 0,
+                svc->announce_callback(svc->p_cookie,
                                        (struct sockaddr*)&ctx->conns[i].intf_addr, NULL);
             }
         }
@@ -850,7 +850,7 @@ mdns_serve(struct mdns_ctx *ctx, mdns_stop_func stop, void *p_cookie)
 
                         for (svc = ctx->services; svc; svc = svc->next) {
                                 if (question->type == svc->type) {
-                                        svc->announce_callback(svc->p_cookie, r,
+                                        svc->announce_callback(svc->p_cookie,
                                                (struct sockaddr*)&ctx->conns[i].intf_addr,
                                                question->name);
                                         goto again;