Unique description of a bidirectional network communication channel. More...

#include <net.h>

Data Fields
uint32_t	error_code

uint32_t	dest_addr

uint16_t	dest_port

uint16_t	ip_tos

uint32_t	src_addr

uint16_t	src_port

uint16_t	res_align2

void *	user_pointer

uint32_t	res_align3 [2]

struct in_struct	in

uint32_t	res [SO_SPARE]

uint32_t	mc_dest_addr

uint32_t	mc_group_addr

uint16_t	mc_dest_port

uint16_t	mc_src_port

uint16_t	proto

uint32_t	option

uint32_t	status

struct out_struct	out

uint8_t	data_type

uint8_t	data_shift

Detailed Description

Main structure to hold all information about a current connection (refer to Sockets). Each connection must have its own socket structure. Use socket_open() to acquire a new socket for a new connection. socket_open() returns a pointer to SOCKET, which is an abbreviation to socket_struct.

Not all socket_struct members are user accessible. Please make sure not to use res[SO_SPARE], which holds important internal information about the current connection (such as connection status, DNS sockets, timing and retransmit values, timeouts etc.). However it is possible to use res_align3[2] and *user_pointer as free scratch registers for application specific use.

The most important user accessible member is error_code. If a transmit function returns a SOCKET_ERROR the user should check the reason:

E.g. in a TCP callback function

switch (socket->error_code & SO_ERROR_MASK)
{
    case SO_NO_ERROR:
        //******************************************************************
        // data received successfully
        //******************************************************************
        break;
    case SO_CONNECTION_ESTABLISHED:
        //******************************************************************
        // connection established
        //******************************************************************
        break;
    case SO_CONNECTION_CLOSED:
        //******************************************************************
        // connection closed
        //******************************************************************
        break;
    case SO_TIMED_OUT:
        //******************************************************************
        // connection timed out, peer not available
        // shutdown connection to prevent a dangling socket
        //******************************************************************
        shutdown (so, 10L);
        CPrintf (" connection closed\r\n");
        break;
    default:
        //******************************************************************
        // else print error
        //******************************************************************
        net_print_error (socket->error_code, CPrintf);
        break;
}

Field Documentation

uint32_t error_code

Socket Error Code

See also: net_send(), net_recv()

uint32_t dest_addr

socket destination address information
it can be used to determine destinations address after successful net_recv()

uint16_t dest_port

socket destination port information
it can be used to determine destinations port after successful net_recv()

uint16_t ip_tos

IP type of service
use immediately before net_send() or after net_recv()

bit 15..8 : receive TOS
bit 7..0 : send TOS

uint32_t src_addr

Local address

uint16_t src_port

Local port

uint16_t res_align2

32 bit alignment.

user_pointer

Free for custom use as a general purpose pointer

Useful to attach additional data to a specific socket
E.g. in example Echo.c:

//**************************************************************************
// attach buffer control structure to socket
//  (required for NBufferAcquireBuffer() later)
//**************************************************************************
tcp_echo_so-> user_pointer = (void *)&bcontrol;