/* Tiny I/O callback called on recv/send I/O events on idle connections.
* It simply sets the CO_FL_SOCK_RD_SH flag so that si_idle_conn_wake_cb()
* is notified and can kill the connection.
*/
static void si_idle_conn_null_cb(struct connection *conn)
{
if (conn->flags & (CO_FL_ERROR | CO_FL_SOCK_RD_SH))
return;
if (fdtab[conn->t.sock.fd].ev & (FD_POLL_ERR|FD_POLL_HUP)) {
fdtab[conn->t.sock.fd].linger_risk = 0;
conn->flags |= CO_FL_SOCK_RD_SH;
}
else {
conn_drain(conn);
}
/* disable draining if we were called and have no drain function */
if (!conn->ctrl->drain)
__conn_data_stop_recv(conn);
}
/**
* 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();
}
}