HP UX 11i v2 Networking Software manual Appendix a 157

	Sample Programs
	Connectionless Mode
AREA_SIZE,	/* maxlen = AREA_SIZE */
0,	/* len gets filled in for each message */
data_area	/* buf = data area */
};

/************************************************************************** get the next message from a stream; get_msg() returns one of the following defines

**************************************************************************/

#define GOT_CTRL	1	/* message has only a control part */
#define GOT_DATA	2	/*	message has only a data part */
#define GOT_BOTH	3	/*	message has both control and data parts */

int
get_msg(fd)
int	fd;	/* file descriptor */
{
int	flags = 0;	/* 0 ---> get any available message */
int	result = 0;	/* return value */

/*

zero first byte of control area so the caller can call check_ctrl without checking the get_msg return value; if there was only data in the message and the user was expecting control or control + data, then when he calls check_ctrl it will compare the expected primitive zero and print information about the primitive that it got.

*/

ctrl_area[0] = 0;

/* call getmsg and check for an error */ if(getmsg(fd, &ctrl_buf, &data_buf, &flags) < 0) {

printf(”error: getmsg failed, errno = %d\n”, errno); exit(1);

}

if(ctrl_buf.len > 0) { result = GOT_CTRL;

}

if(data_buf.len > 0) { result = GOT_DATA;

}

return(result);

}

/************************************************************************** check that control message is the expected message

**************************************************************************/

void
check_ctrl(ex_prim)
int	ex_prim;	/* the expected primitive */
{
dl_error_ack_t		*err_ack = (dl_error_ack_t *)ctrl_area;

/* did we get the expected		primitive? */
if(err_ack->dl_primitive	!= ex_prim) {
/* did we get a	control part */
if(ctrl_buf.len)	{
/* yup;	is it an ERROR_ACK? */

Appendix A 157