#
/* in_read.c */

/* EMACS_MODES: c !fill */


/* Internet protocol layer for the MIT network system.  The following
 * routines are included:
 *	in_read		Read the next available packet from an internet conn.
 *
 * Note that use of this package requires the use of the standard I/O
 * library.
 */


#include	<err.h>
#include	<stdio.h>
#include	<ioctl.h>
#include	<ip.h>
#include	<netdefs.h>


in_read (fd, buf, len)

/* Read the next available internet packet for the specified connection from
 * the net into the specified buffer.  Return the length of the received
 * packet in bytes.
 * The macro in_data may be called to obtain a pointer to the start
 * of the data area of the packet.
 * If no packet is available (read returns NULL) or if the specified
 * buffer is too small, return 0.
 * Note: bad packets are simply dropped, and the dropped
 * packet count is incremented.
 *
 * Arguments:
 */

int	fd;				/* file descriptor for this conn. */
reg	caddr_t	buf;			/* buffer for received data */
int	len;				/* buffer size */
{
	reg	int	rcvlen;		/* length of actual received pkt */
	reg	int	maxlen;		/* max. inet packet length */
	
	if ((rcvlen = read (fd, buf, len)) <= (lnhsiz + IPHSIZ)) {
		ip_dropped++;
		return (0);
	}
	ip_rcvd++;
	return (rcvlen);
}