tcp_get_state

Summary

#include <rtl.h>

U8 tcp_get_state (
    U8 socket );    /* TCP socket to get the state of. */

Description

The tcp_get_state function determines the current state of the TCP socket. Your application can use the tcp_get_state function to monitor the progress when establishing a connection or when closing the connection. The most useful state values are TCP_STATE_CLOSED, TCP_STATE_LISTEN, and TCP_STATE_CONNECT. The argument socket specifies the handle of the socket to get the state of.

The tcp_get_state function is in the RL-TCPnet library. The prototype is defined in rtl.h.

Return Value

The tcp_get_state function returns the current state of the TCP socket.

State	Description
TCP_STATE_FREE	Socket is free and not allocated yet. The function cannot return this value.
TCP_STATE_CLOSED	Socket is allocated to an application but the connection is closed.
TCP_STATE_LISTEN	Socket is listening for incoming connections.
TCP_STATE_SYN_REC	Socket has received a TCP packet with the flag SYN set.
TCP_STATE_SYN_SENT	Socket has sent a TCP packet with the flag SYN set.
TCP_STATE_FINW1	Socket has sent a FIN packet, to start the closing of the connection.
TCP_STATE_FINW2	Socket has received acknowledgement from the remote machine for the FIN packet it sent out from the local machine. Socket is now waiting for a FIN packet from the remote machine.
TCP_STATE_CLOSING	Socket has received a FIN packet from the remote machine independently
TCP_STATE_LAST_ACK	Socket is waiting for the last ACK packet to the FIN packet it sent out.
TCP_STATE_TWAIT	Socket is waiting on a 2 ms timeout before closing the connection.
TCP_STATE_CONNECT	Socket has established a TCP connection. You can transfer data only in this state.

See Also

tcp_check_send

Example

#include <rtl.h>

void send_data () {
  U8 remip[4] = {192,168,1,100};
  U8 *sendbuf;

  switch (tcp_get_state (socket_tcp)) {
    case TCP_STATE_FREE:
    case TCP_STATE_CLOSED:
      /* Connection idle, send Connect Request. */
      tcp_connect (socket_tcp, Rem_IP, 1001, 0);
      break;
    case TCP_STATE_CONNECT:
      /* We are connected, send command to remote peer. */
      if (tcp_check_send (socket_tcp)) {
        /* OK, socket is ready to send data. */
        sendbuf = tcp_get_buf (2);
        sendbuf[0] = BLINKLED;
        sendbuf[1] = p2;
        tcp_send (socket_tcp, sendbuf, SENDLEN);
      }
      break;
  }
}