MQTT disconnect message not implemented (IDFGH-835)

[gregjesl]

Duplicate issue of https://github.com/espressif/esp-mqtt/issues/97 (which does not appear to be tracked in your issue tracking database).

Issue

The MQTT client never sends the DISCONNECT packet to the broker. This results in the last will and testament always being sent, which is not the intended behavior.

Solution

I submitted the fix in https://github.com/espressif/esp-mqtt/pull/106

[gregjesl]

@david-cermak I targeted the idf branch in my pull request but I branched from the master branch. Should I branch from the idf branch for my pull request?

[david-cermak]

@gregjesl Thank you for your help with this issue!

Yes please keep the idf as target branch (will soon merge it to master), but you seem to have to rebase onto idf.

[gregjesl]

Closed per https://github.com/espressif/esp-mqtt/commit/caf5007b99df985b330683dfe2fa454c94633018

[gregjesl]

Reopened - submodule needs to be updated.

[mastertheknife]

Hi, This is also the case with ESP8266, on the latest SDK (RTOS v3.2 - released 22 days ago) As a temporary workaround for my project, i copied these changes into esp_mqtt_client_stop() and they work well. I can confirm that the change (and the subsequent one to only disconnect if connected: https://github.com/espressif/esp-mqtt/pull/118) work on the ESP8266:

--- mqtt_client.c.orig  2019-07-05 22:37:13.604686922 +0300
+++ mqtt_client.c   2019-07-05 22:53:15.787319054 +0300
@@ -788,6 +788,12 @@
 esp_err_t esp_mqtt_client_stop(esp_mqtt_client_handle_t client)
 {
     if (client->run) {
+        if(client->state == MQTT_STATE_CONNECTED) {
+            client->mqtt_state.outbound_message = mqtt_msg_disconnect(&client->mqtt_state.mqtt_connection);
+            if (mqtt_write_data(client) != ESP_OK) {
+                ESP_LOGE(TAG, "Error sending disconnect message");
+            }
+        }
         client->run = false;
         xEventGroupWaitBits(client->status_bits, STOPPED_BIT, false, true, portMAX_DELAY);
         client->state = MQTT_STATE_UNKNOWN;