MQTT configure connection parameters not working

[Palonso]

Hi,

I'm trying to connect to an MQTT server and I found the next problem.

when setting the parameters one by one, like this:

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esp_mqtt_client_config_t mqtt_cfg;
memset(&mqtt_cfg, 0, sizeof(esp_mqtt_client_config_t));
mqtt_cfg.host = (char *)hostname;
mqtt_cfg.port = port;
mqtt_cfg.client_id = (char *)client_id;
mqtt_cfg.username = (char *)username;
mqtt_cfg.password = (char *)password;
mqtt_cfg.cert_pem = (const char *)mqttserver_pub_pem_start;
esp_mqtt_set_config(mqtt_client, &mqtt_cfg);

the ESP can't connect to the server and I get the next log output:

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I (6178) esp_netif_handlers: sta ip: 192.168.1.22, mask: 255.255.255.0, gw: 192.168.1.1
I (6178) mqtt: MQTT_EVENT_BEFORE_CONNECT
E (6258) TRANS_TCP: DNS lookup failed err=202 res=0x0
E (6258) MQTT_CLIENT: Error transport connect
I (6258) mqtt: MQTT_EVENT_ERROR
I (6258) mqtt: MQTT_EVENT_DISCONNECTED

BUT when setting the parameters like this:

Code: Select all

esp_mqtt_client_config_t mqtt_cfg = 
{
	.uri = (char *)hostname,
	.cert_pem = (const char *)mqttserver_pub_pem_start,
	.port = port,
	.client_id = (char *)client_id,
	.username = (char *)username,
	.password = (char *)password,
};
esp_mqtt_set_config(mqtt_client, &mqtt_cfg);

I'm able to connect to the server and got the next log output:

Code: Select all

I (4159) esp_netif_handlers: sta ip: 192.168.1.22, mask: 255.255.255.0, gw: 192.168.1.1
I (4159) mqtt: MQTT_EVENT_BEFORE_CONNECT
I (6339) mqtt: MQTT_EVENT_CONNECTED

Does anybody knows where is the problem with one way of configuring the MQTT server parameters and the other?

Best regards,
P

[PeterR]

You need to supply the initialisers. Also would help to know if you are compiling C or C++.
Something in the structure wants to be true or else you get the DNS error.
memset() is always a good idea but in your case you want a member to be true. Won't take you long to examine the structure & trial & error.

May help to note that the initialiser rules changed between C & C++. In your code what you do not set will (typically) be non zero and so true.
Memset the structure then set what you want & sleep at night knowing that all is defined. If not sure what to set then examine the structure and binary chop setting bools till you find the flag.

[Palonso]

I found that the difference with one way and the other is the member I was setting.

In one I was setting the host and the other the uri wich may seem to be the same but are really different.

Thanks for the advice.