Hello,
I am having some trouble retrieving the mqtt topic which are published on, and the data within.
I've used the mqtt_simple as a starting point.
static int subscribe(void)
{
memset(example, 0, sizeof(example));
memset(example1, 0, sizeof(example1));
memset(example2, 0, sizeof(example2));
fetch_topic();
strcpy(example1, example);
strcpy(example2, example);
strcat(example, "/fota");
strcat(example1, "/position");
strcat(example1, "/status");
strcat(example2, "/position");
printf(example);
printf(example1);
printf(example2);
struct mqtt_topic subscribe_topics[] = {
{
.topic = {
.utf8 = example,
.size = strlen(example)
},
.qos = MQTT_QOS_1_AT_LEAST_ONCE
},
{
.topic = {
.utf8 = example1,
.size = strlen(example1)
},
.qos = MQTT_QOS_1_AT_LEAST_ONCE
},
{
.topic = {
.utf8 = example2,
.size = strlen(example2)
},
.qos = MQTT_QOS_1_AT_LEAST_ONCE
}
};
const struct mqtt_subscription_list subscription_list = {
.list = subscribe_topics,
.list_count = ARRAY_SIZE(subscribe_topics),
.message_id = 1234
};
printk("Subscribing to: %s len %u\n", example,
(unsigned int)strlen(example));
printk("Subscribing to: %s len %u\n", example1,
(unsigned int)strlen(example1));
printk("Subscribing to: %s len %u\n", example2,
(unsigned int)strlen(example2));
return mqtt_subscribe(&client, &subscription_list);
}
/**@brief Function to read the published payload.
*/
static int publish_get_payload(struct mqtt_client *c, size_t length)
{
memset(payload_buf, 0, sizeof(payload_buf));
uint8_t *buf = payload_buf;
uint8_t *end = buf + length;
if (length > sizeof(payload_buf)) {
return -EMSGSIZE;
}
while (buf < end) {
int ret = mqtt_read_publish_payload(c, buf, end - buf);
if (ret < 0) {
int err;
if (ret != -EAGAIN) {
return ret;
}
printk("mqtt_read_publish_payload: EAGAIN\n");
err = poll(&fds, 1,
CONFIG_MQTT_KEEPALIVE * MSEC_PER_SEC);
if (err > 0 && (fds.revents & POLLIN) == POLLIN) {
continue;
} else {
return -EIO;
}
}
if (ret == 0) {
return -EIO;
}
buf += ret;
}
return 0;
}
/**@brief MQTT client event handler
*/
void mqtt_evt_handler(struct mqtt_client *const c,
const struct mqtt_evt *evt)
{
int err;
switch (evt->type) {
case MQTT_EVT_CONNACK:
if (evt->result != 0) {
printk("MQTT connect failed %d\n", evt->result);
break;
}
printk("[%s:%d] MQTT client connected!\n", __func__, __LINE__);
#if defined(CONFIG_MQTT_LIB_TLS)
printk("Connected with TLS\n");
#endif
subscribe();
break;
case MQTT_EVT_DISCONNECT:
printk("[%s:%d] MQTT client disconnected %d\n", __func__,
__LINE__, evt->result);
break;
case MQTT_EVT_PUBLISH: {
const struct mqtt_publish_param *p = &evt->param.publish;
printk("[%s:%d] MQTT PUBLISH result=%d len=%d\n", __func__,
__LINE__, evt->result, p->message.payload.len);
err = publish_get_payload(c, p->message.payload.len);
if (err >= 0) {
data_print("Received: ", payload_buf,
p->message.payload.len);
printk("len=%d\n", p->message.payload.len);
printk("Topic: %s\n", evt->param.publish.message);
/* Echo back received data */
/*
data_publish(&client, MQTT_QOS_1_AT_LEAST_ONCE,
payload_buf, p->message.payload.len);
*/
} else {
printk("mqtt_read_publish_payload: Failed! %d\n", err);
printk("Disconnecting MQTT client...\n");
err = mqtt_disconnect(c);
if (err) {
printk("Could not disconnect: %d\n", err);
}
}
} break;
case MQTT_EVT_PUBACK:
if (evt->result != 0) {
printk("MQTT PUBACK error %d\n", evt->result);
break;
}
printk("[%s:%d] PUBACK packet id: %u\n", __func__, __LINE__,
evt->param.puback.message_id);
break;
case MQTT_EVT_SUBACK:
if (evt->result != 0) {
printk("MQTT SUBACK error %d\n", evt->result);
break;
}
printk("[%s:%d] SUBACK packet id: %u\n", __func__, __LINE__,
evt->param.suback.message_id);
break;
case MQTT_EVT_PINGRESP:
if (evt->result != 0) {
printk("MQTT PINGRESP error %d\n", evt->result);
}
break;
default:
printk("[%s:%d] default: %d\n", __func__, __LINE__,
evt->type);
break;
}
}
/**@brief Resolves the configured hostname and
* initializes the MQTT broker structure
*/
I managed to printk, the momentary topic, used with : printk("Topic: %s\n", evt->param.publish.message);
If I publish to another topic, which is longer in size, the result will look like this :
Topic: es400/89470060190924044097/position/status
[mqtt_evt_handler:572] MQTT PUBLISH result=0 len=1
Received: K
len=1
Topic: es400/89470060190924044097/fotation/status
[mqtt_evt_handler:572] MQTT PUBLISH result=0 len=1
Received: K
len=1
---
I need a way to store the topic so that I can differenciate between the published topic, and also store the data within a variable for later use.
Any ideas will be appreciated.
Regards, David
