Missing merge from ESPNow cleanup

host/host_central_mast/src/main.cpp

@@ -61,8 +61,14 @@ void on_data_sent(const uint8_t *mac_addr, esp_now_send_status_t status) {
 
 void on_data_recv(const uint8_t *mac, const uint8_t *incomingData, int len) {
 
-    esp_log_write(ESP_LOG_INFO, TAG_ESPNOW, "Message received\n");
+    response response = {};
+    // send a host change msg if client is new, simplifies client
+    response.type = esp_now_is_peer_exist(mac) ? dataAck : hostChange;
+    esp_read_mac(response.mac, ESP_MAC_WIFI_STA);
+    response.time = rtc.getEpoch();
 
+    // this block needs to happen before we send the message, as it's not possible to
+    // send a message to an unregistered peer (i.e. new client)
     if (!esp_now_is_peer_exist(mac)) {
         esp_now_peer_info_t client = {};
         memcpy(client.peer_addr, mac, sizeof(uint8_t) * 6);
@@ -75,11 +81,6 @@ void on_data_recv(const uint8_t *mac, const uint8_t *incomingData, int len) {
         }
     }
 
-    // TODO: Think if response to client may contain error messages
-    response response = {};
-    response.type = dataAck;
-    esp_read_mac(response.mac, ESP_MAC_WIFI_STA);
-    response.time = rtc.getEpoch();
     esp_err_t success = esp_now_send(mac, (uint8_t *)&response, sizeof(response));
     esp_log_write(ESP_LOG_DEBUG, TAG_ESPNOW, (success == ESP_OK) ? "Response sent\n" : "Failed to respond\n");