int keepalive(MQTTClient *c)
{
int rc = SUCCESS;
if (c->keepAliveInterval == 0) {
goto exit;
}
if (TimerIsExpired(&c->last_sent) || TimerIsExpired(&c->last_received)) {
if (c->ping_outstanding && TimerIsExpired(&c->ping_wait)) {
rc = FAILURE; /* PINGRESP not received in keepalive interval */
} else {
Timer timer;
TimerInit(&timer);
TimerCountdownMS(&timer, 1000);
int len = MQTTSerialize_pingreq(c->buf, c->buf_size);
if (len > 0 && (rc = sendPacket(c, len, &timer)) == SUCCESS) { // send the ping packet
c->ping_outstanding = 1;
TimerCountdownMS(&c->ping_wait, CONFIG_MQTT_PING_TIMEOUT);
}
}
}
exit:
return rc;
}
int waitfor(MQTTClient* c, int packet_type, Timer* timer)
{
int rc = FAILURE;
do {
if (TimerIsExpired(timer))
break; // we timed out
} while ((rc = cycle(c, timer)) != packet_type);
return rc;
}
int MQTTYield(MQTTClient *c, int timeout_ms)
{
int rc = SUCCESS;
Timer timer;
TimerInit(&timer);
TimerCountdownMS(&timer, timeout_ms);
do {
if (cycle(c, &timer) < 0) {
rc = FAILURE;
break;
}
} while (!TimerIsExpired(&timer));
return rc;
}
static int sendPacket(MQTTClient* c, int length, Timer* timer)
{
int rc = FAILURE, sent = 0;
while ((sent < length) && !TimerIsExpired(timer)) {
rc = c->ipstack->mqttwrite(c->ipstack, &c->buf[sent], length, TimerLeftMS(timer));
if (rc < 0)
break;
sent += rc;
}
/*
The send progress only send the packet to the socket buffer
we dont know if it successeds, default it is SUCCESS
*/
if (sent == length) {
rc = SUCCESS;
} else {
rc = FAILURE;
}
return rc;
}
static int sendPacket(MQTTClient *c, int length, Timer *timer)
{
int rc = FAILURE,
sent = 0;
while (sent < length && !TimerIsExpired(timer)) {
rc = c->ipstack->mqttwrite(c->ipstack, &c->buf[sent], length, TimerLeftMS(timer));
if (rc < 0) { // there was an error writing the data
break;
}
sent += rc;
}
if (sent == length) {
TimerCountdown(&c->last_sent, c->keepAliveInterval); // record the fact that we have successfully sent the packet
rc = SUCCESS;
} else {
rc = FAILURE;
}
return rc;
}
int keepalive(MQTTClient* c)
{
int rc = SUCCESS;
if (c->keepAliveInterval == 0) {
rc = SUCCESS;
goto exit;
}
if (TimerIsExpired(&c->ping_timer)) {
printf("keep alive counter expired\n");
if (!c->ping_outstanding) {
printf("keep alive counter reset\n");
//Set the pingreq send timeout
Timer timer;
TimerInit(&timer);
TimerCountdownMS(&timer, 1000);
int len = MQTTSerialize_pingreq(c->buf, c->buf_size);
/* If the sendPacket success, the keep alive works with keepAliveInterval */
if (len > 0 && (rc = sendPacket(c, len, &timer)) == SUCCESS) {// send the ping packet
c->ping_outstanding = 1;
TimerCountdown(&c->ping_timer, c->keepAliveInterval); // record the fact that we have successfully sent the packet
} else {
rc = FAILURE;
}
} else {
printf("keep alive counter failure\n");
rc = FAILURE;
}
}
exit:
return rc;
}
