tcp_get_socket

#include <rtl.h>

U8 tcp_get_socket (
    U8   type,          /* Type of TCP socket. */
    U8   tos,           /* Type Of Service. */
    U16  tout,          /* Idle timeout period before disconnecting. */
    U16 (*listener)(    /* Function to call when a TCP event occurs. */
        U8  socket,     /* Socket handle of the local machine. */
        U8  event,      /* TCP event such as connect, or close. */
        U8* ptr,        /* Pointer to IP address of remote machine, */
                        /*   or to buffer containing received data. */
        U16 par ));     /* Port number of remote machine, or length */
                        /* of received data. */

The tcp_get_socket function allocates a free TCP socket. The function initializes all the state variables of the TCP socket to the default state.

The argument type specifies the type of the TCP socket.

The argument tos specifies the IP Type Of Service. The most common value for tos is 0.

The argument tout specifies the idle timeout in seconds. The TCP connection is supervised by the keep alive timer. When the connection has been idle for more than tout seconds, TCPnet disconnects the the TCP connection or sends a keep-alive packet if TCP_TYPE_KEEP_ALIVE attribute is set.

The argument listener is the event listening function of the TCP socket. TCPnet calls the listener function whenever a TCP event occurs. The arguments to the listener function are:

• socket: TCP socket handle of the local machine.
• event: Specifies the type of event that occurred as shown in the table below.
• ptr: If event is TCP_EVT_DATA, ptr points to a buffer containing the received data. For all other events, ptr points to the IP address of the remote machine.
• par: If event is TCP_EVT_DATA, par specifies the number of bytes of data received. For all other events, par specifies the port number used by the remote machine.

TCPnet uses the return value of the callback function listener only when the event is TCP_EVT_CONREQ. It uses the return value to decide whether to accept or reject an incoming connection when the TCP socket is listening. If the listener function returns 1, TCPnet accepts the incoming connection. If the listener function returns 0, TCPnet rejects the incoming connection. You can thus define the listener function to selectively reject incoming connections from particular IP addresses.

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

note

• You must call the tcp_get_socket function before any other function calls to the TCP socket.
• You must define the listener function to use with the TCP socket.
• You must use the TCP_TYPE_KEEP_ALIVE attribute for a longstanding connection.

The tcp_get_socket function returns the handle of the allocated TCP socket. If the function could not allocate a socket, it returns 0.

tcp_connect, tcp_listen, tcp_release_socket, tcp_reset_window

#include <rtl.h>

U8 tcp_soc;

U16 tcp_callback (U8 soc, U8 event, U8 *ptr, U16 par) {
  /* This function is called on TCP event */
   ..
  switch (event) {
    case TCP_EVT_CONREQ:
      /* Remote host is trying to connect to our TCP socket. */
      /* 'ptr' points to Remote IP, 'par' holds the remote port. */
       ..
      /* Return 1 to accept connection, or 0 to reject connection */
      return (1);
    case TCP_EVT_ABORT:
      /* Connection was aborted */
       ..
      break;
    case TCP_EVT_CONNECT:
      /* Socket is connected to remote peer. */
       ..
      break;
    case TCP_EVT_CLOSE:
      /* Connection has been closed */
       ..
      break;
    case TCP_EVT_ACK:
      /* Our sent data has been acknowledged by remote peer */
       ..
      break;
    case TCP_EVT_DATA:
      /* TCP data frame has been received, 'ptr' points to data */
      /* Data length is 'par' bytes */
       ..
      break;
  }
  return (0);
}

void main (void) {

  init ();
  /* Initialize the TcpNet */
  init_TcpNet ();
  tcp_soc = tcp_get_socket (TCP_TYPE_SERVER, 0, 30, tcp_callback);
  if (tcp_soc != 0) {
    /* Start listening on TCP port 80 */
    tcp_listen (tcp_soc, 80);
  }

  while (1);
    /* Run main TcpNet 'thread' */
    main_TcpNet ();
     ..
  }
}