Unknown condition satisfaction in pthread cond timedwait - c

Question

There's something going on in my code that I didn't intend.
I've got a program with several threads. One thread reads a rfid chip and saves the rfid code string into a global struct variable. There are also some other threads that are opened when a client, which is supposed to get the string, connects to the program on a certain socket. They are on a timed waiting (pthread_cond_timedwait) for the reading thread to broadcast a pthread condition variable (thread->done) that signals that a rfid chip was read and there is a new string to be sent to the clients. Now to the problem: the pthread_cond_timedwait in the sending thread shall only be satisfied when a new string is ready to be sent, but it also triggers when a new client thread is opened. The client threads start with the function below. I hope I explained my problem clearly and anyone can help me with the problem.
code of the sending function:
void* send_data(void* arg)
{
int client_id;
int status_timeout;
struct timespec timeout;
struct Thread_parameter *thread = (struct Thread_parameter*)arg;
pthread_condattr_t attr;
pthread_condattr_init(&attr);
pthread_condattr_setclock(&attr, CLOCK_MONOTONIC);
pthread_cond_init(&thread->done, &attr);
// read the client id from struct
pthread_mutex_lock(&thread->mutex);
client_id = thread->t_client_id;
pthread_mutex_unlock(&thread->mutex);
while (1)
{
// wait for string
while (1)
{
pthread_mutex_lock(&thread->mutex);
status_timeout = ETIMEDOUT;
while (1)
{
clock_gettime(CLOCK_MONOTONIC, &timeout);
timeout.tv_sec += 1;
status_timeout = pthread_cond_timedwait(&thread->done, &thread->mutex, &timeout);
// Timeout
if (status_timeout == ETIMEDOUT)
{
if (is_connected(client_id))
continue;
else
{
log_output("Lost connection to client '%i'", client_id);
pthread_mutex_unlock(&thread->mutex);
pthread_exit(NULL);
}
}
else if (status_timeout == 0)
{
// condition satisfied
break;
}
}
pthread_mutex_unlock(&thread->mutex);
break;
}
// send the string to the client when the condition is satisfied
while (1)
{
pthread_mutex_lock(&thread->mutex);
if (send(client_id, thread->t_chip_id, CHIP_ID_LENGTH, MSG_NOSIGNAL) >= 0)
{
pthread_mutex_unlock(&thread->mutex);
log_output("Successfully sent data to client '%i'", client_id);
break;
}
else
{
pthread_mutex_unlock(&thread->mutex);
// sending not successful, check if client is still connected
if (is_connected(client_id))
continue;
else
{
close(client_id);
log_output("Lost connection to client '%i'", client_id);
pthread_exit(NULL);
}
}
}
}
}