void
rel_timer ()
{
/* Iterate over all the reliable connections */
rel_t *r;
for (r = rel_list; r != NULL; r = r->next) {
/* Poke the output, just in case it died on us */
rel_output(r);
/* Send window is [head of buffer queue, head of buffer queue + window size],
* so we iterate over the send window, and send anything that's timed out. */
int i = 0;
for (i = bq_get_head_seq(r->send_bq); rel_seqno_in_send_window(r,i); i++) {
/* This is just a safety check, in case we haven't read in this part
* of the send window yet */
if (!bq_element_buffered(r->send_bq, i)) continue;
/* Borrowed need_timer_in from rlib: just checks whether it's
* been r->timeout ms since elem->time_sent */
send_bq_element_t *elem = bq_get_element(r->send_bq, i);
if (need_timer_in (&(elem->time_sent), r->timeout) == 0) {
rel_send_buffered_pkt(r,elem);
}
}
}
}
/**
* Main loop. Handles the following:
* - Input from STDIN.
* - Messages from programs.
* - Packets from the socket.
* - Timeouts.
*/
void do_loop() {
char buf[MAX_PACKET_SIZE];
conn_t *conn = NULL;
while (true) {
memset(buf, 0, MAX_PACKET_SIZE);
poll(events, NUM_POLL + num_connected,
need_timer_in(&last_timeout, ctcp_cfg->timer));
/* Input from stdin. Server will only send to most-recently connected
client. */
if (!run_program && events[STDIN_FILENO].revents & POLLIN) {
conn = get_connections();
if (conn != NULL)
ctcp_read(conn->state);
}
/* See if we can output more. */
if (events[STDOUT_FILENO].revents & (POLLOUT | POLLHUP | POLLERR)) {
for (conn = get_connections(); conn; conn = conn->next) {
conn_drain(conn);
}
}
/* Poll for output received from running programs. Send to client
client associated with this program instance. */
if (run_program) {
conn = get_connections();
while (conn != NULL) {
if (conn->poll_fd->revents & POLLIN) {
ctcp_read(conn->state);
}
conn = conn->next;
}
}
/* Receive packet on socket from other hosts. Ignore packets if they are
not large enough or not for us. */
if (events[2].revents & POLLIN) {
conn = NULL;
int len = recv_filter(config->socket, buf, MAX_PACKET_SIZE, 0, &conn);
if (len >= FULL_HDR_SIZE) {
tcphdr_t *tcp_hdr = (tcphdr_t *) (buf + IP_HDR_SIZE);
/* Packet from an established connection. Pass to student code. */
if (conn != NULL) {
ctcp_segment_t *segment = convert_to_ctcp(conn, buf, len);
len = len - FULL_HDR_SIZE + sizeof(ctcp_segment_t);
/* Don't log or forward to student code if it's an ACK from a new
connection. */
if (tcp_hdr->th_sport == new_connection &&
(segment->flags & TH_ACK) &&
ntohl(segment->seqno) == 1 && ntohl(segment->ackno) == 1) {
new_connection = 0;
free(segment);
}
else {
if (log_file != -1 || test_debug_on) {
log_segment(log_file, config->ip_addr, config->port, conn,
segment, len, false, unix_socket);
}
ctcp_receive(conn->state, segment, len);
}
}
/* New connection. */
else if (tcp_hdr->th_flags & TH_SYN) {
conn_t *conn = tcp_new_connection(buf);
/* Start a new program associated with this client. */
if (run_program && conn)
execute_program(conn);
new_connection = tcp_hdr->th_sport;
}
}
}
/* Check if timer is up. */
if (need_timer_in(&last_timeout, ctcp_cfg->timer) == 0) {
ctcp_timer();
get_time(&last_timeout);
}
/* Delete connections if needed. */
delete_all_connections();
}
}
