Multibale connection in Contiki-ng Stack error - c

Question

I'm trying to implement my version of clustering in Contiki-ng. I took some inspiration from this code: Clustring example
What I did basically was that I created two connection:
static struct simple_udp_connection broad_conn;
static struct simple_udp_connection uni_conn;
However, though the code compiles and starts running in cooja, it stops showing me an error in the stack. I traced the error message and it looked like it came from this part of the code in stack-check.c:
if(p >= (uint8_t*)GET_STACK_ORIGIN()) {
/* This means the stack is screwed. */
return -1;
}
actual = stack_check_get_usage();
allowed = stack_check_get_reserved_size();
if(actual < 0 || allowed < 0) {
LOG_ERR("Check in inconsistent state: %" PRId32 " vs. %" PRId32 "\n", actual, allowed);
There is no memory overflow, and besides the callback functions, there is nothing in the code. The only thing that I think off is that it's because of the connections, but I just don't see why.
This is the code of nodes.c:
#include "contiki.h"
#include "simple-udp.h"
#include "sys/log.h"
#define LOG_MODULE "SensorNode"
#define LOG_LEVEL LOG_LEVEL_INFO
#define UDP_PORT_BROADCAST 1234
#define UDP_PORT_UNICAST 4321
static struct simple_udp_connection broadcast_conn;
static struct simple_udp_connection unicast_conn;
static uip_ipaddr_t CH_address;
PROCESS(nodes_process, "Nodes");
AUTOSTART_PROCESSES(&nodes_process);
/*---------------------------------Not Me------------------------------------------*/
static void
broadcast_receiver(struct simple_udp_connection *c,
const uip_ipaddr_t *sender_addr,
uint16_t sender_port,
const uip_ipaddr_t *receiver_addr,
uint16_t receiver_port,
const uint8_t *data,
uint16_t datalen)
{
LOG_INFO("Received broadcast '%.*s' from ", datalen, (char *) data);
LOG_INFO_6ADDR(sender_addr);
LOG_INFO_("\n");
uip_ipaddr_copy(&CH_address, sender_addr);
}
/*---------------------------------------------------------------------------*/
static void
unicast_receiver(struct simple_udp_connection *c,
const uip_ipaddr_t *sender_addr,
uint16_t sender_port,
const uip_ipaddr_t *receiver_addr,
uint16_t receiver_port,
const uint8_t *data,
uint16_t datalen)
{
LOG_INFO("Received reply '%.*s' from ", datalen, (char *) data);
LOG_INFO_6ADDR(sender_addr);
LOG_INFO_("\n");
}
/*---------------------------------------------------------------------------*/
PROCESS_THREAD(nodes_process, ev, data)
{
static struct etimer periodic_timer;
static unsigned count;
static char str[32];
PROCESS_BEGIN();
/* Not me also */
/* Initialize UDP broadcast connection */
simple_udp_register(&broadcast_conn, UDP_PORT_BROADCAST, NULL,
UDP_PORT_BROADCAST, broadcast_receiver);
/* Initialize UDP unicast connection */
simple_udp_register(&unicast_conn, UDP_PORT_UNICAST, NULL,
UDP_PORT_UNICAST, unicast_receiver);
/* Send messages to the clusterhead every 60 seconds */
etimer_set(&periodic_timer, 60*CLOCK_SECOND);
while(1) {
PROCESS_WAIT_EVENT_UNTIL(etimer_expired(&periodic_timer));
LOG_INFO("Sending message %u to ", count);
LOG_INFO_6ADDR(&CH_address);
LOG_INFO_("\n");
snprintf(str, sizeof(str), "hello %d", count);
simple_udp_sendto(&unicast_conn, str, strlen(str), &CH_address);
count++;
etimer_reset(&periodic_timer);
}
PROCESS_END();
}
Any help in explaining this would be great.
Thank you.