MQTTClient_setCallbacks() will always create socket and not close it - c

Question

My System OS is Linux, Use C for development, My MQTT Library is "paho-MQTT"
The simple application below will run for a while before generating a "open too much files" error. I have attempted to diagnose using losf command to find out what is the fd not closed.
I believed I had traced the issue to the MQTT Function "MQTTClient_setCallbacks()" but that seems OK. Currently I'm unable to find out the true cause of the error.
Note: When this problem occurs, the device has no external network capability, so will be in an infinite loop attempting to connect.
My code is below as:
int InternalSock::MQTTSubscribe()
{
MQTTClient client;
MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
int rc;
int ch;
const char *TOPIC=ModTcpIPA->DC1SN[0];
const char *address;
if (ModTcpIPA->ThirdPartyMode == 1) {
address = "ws://52.163.118.233:8080"; //3rd party
}
else {
address = "ws://52.187.179.41:8080"; //delta
}
const char *client_id=ModTcpIPA->DC1SN[0];
char *chs = ModTcpIPA->DC1SN[0];
char **topic=&chs;
disconnectflag = 1;
ModTcpIPA->MQTTSubscribing = 0;
MQTTClient_create(&client, address, client_id, MQTTCLIENT_PERSISTENCE_NONE, NULL);
conn_opts.keepAliveInterval = 30;
conn_opts.cleansession = 0;
if (ModTcpIPA->ThirdPartyMode == 1) {
conn_opts.username = THIRDPARTYUSERNAME;
conn_opts.password = THIRDPARTYPASSWORD;
}
else {
conn_opts.username = DELTAUSERNAME;
conn_opts.password = DELTAPASSWORD;
}
conn_opts.MQTTVersion = MQTTVERSION_3_1;
while(!ModTcpIPA->CloseMQTTThread){
if(disconnectflag == 1){
MQTTClient_setCallbacks(client, NULL, connlost, msgarrvd, delivered);
disconnectflag = 0;
}
if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
{
//if(ModTcpIPA->CloudRegist_st == 1){
printf("Failed to connect, return code %d\n", rc);
//}
}else{
printf("Subscribing to topic %s\nfor client %s using QoS%d\n\n"
"Press Q<Enter> to quit\n\n", TOPIC, client_id, QOS);
MQTTClient_subscribe(client, TOPIC, QOS);
ModTcpIPA->MQTTSubscribing = 1;
while(disconnectflag == 0){
if(strlen(MQTTBuff)!= 0){
ParseMQTTMsg(&client);
}
sleep(1);
}
ModTcpIPA->MQTTSubscribing = 0;
MQTTClient_unsubscribe(client, TOPIC);
MQTTClient_disconnect(client, 10000);
}
sleep(3);
}
MQTTClient_destroy(&client);
return rc;
}
add callback functions:
void delivered(void *context, MQTTClient_deliveryToken dt)
{
printf("Message with token value %d delivery confirmed\n", dt);
deliveredtoken = dt;
}
int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message *message)
{
int i;
char* payloadptr;
printf("Message arrived\n");
printf(" topic: %s\n", topicName);
printf(" message: ");
payloadptr = (char*)message->payload;
for(i=0; i<message->payloadlen; i++)
{
putchar(*payloadptr++);
}
putchar('\n');
memset(MQTTBuff, '\0', sizeof(MQTTBuff));
memcpy(MQTTBuff, message->payload, message->payloadlen);
MQTTClient_freeMessage(&message);
MQTTClient_free(topicName);
return 1;
}
void connlost(void *context, char *cause)
{
printf("\nConnection lost\n");
printf(" cause: %s\n", cause);
disconnectflag = 1;
}