#
/* in_open.c */

/* EMACS_MODES: c !fill */


/* Internet protocol layer for the MIT network system.  The following
 * routines are included:
 *	in_open		Open an internet connection
 *
 * 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_open (prot, fhost, fsock, lsock)

/* Open an internet connection on the specified protocol, to the
 * specified foreign host, with the specified local and foreign
 * sockets.  Note that any or all of the arguments may be NULL
 * to indicate that field is to be ignored in packet demultiplexing.
 * Also get the local net header/trailer sizes for this connection.
 * Finally, get the maximum fragment size for this connection and,
 * allocate a packet buffer of the maximum fragment size for
 * later use in packet fragmentation.
 * Note that this routine must be called before attempting to
 * allocate a packet for this connection.
 * Return the file descriptor, or -1 for error (with the error
 * specified in the global variable in_err).
 *
 * Arguments:
 */

unshort	prot;				/* InterNet protocol ID */
in_name	fhost;				/* foreign host addr */
unshort	fsock;				/* foreign socket */
unshort	lsock;				/* local socket */
{
	struct	netdf	ndf;		/* net connection definition */
	reg	struct	netdf	*nf;	/* ptr. to ndf */
	reg	int	fd;		/* file descriptor */
	int	ht[2];			/* array for ioctl */
	struct	{			/* for frag. size ioctl */
		in_name f_name;		/* host addr */
		int	f_size;		/* max. frag size */
	} frgsiz;
	
	nf = &ndf;
	nf->nd_prot1 = MITINET;		/* set up connection definition */
	nf->nd_prot2 = prot;
	nf->nd_fhost = fhost;
	nf->nd_fsock = fsock;
	nf->nd_lsock = lsock;
	
	if ((fd = netopen (NETDEV, nf)) < 0) {
		in_err = errno;
		return (-1);		/* failed to open conn */
	}
	
	if (!in_inited)	{		/* init in layer if needed */
		in_inited = TRUE;
		ioctl (fd, NIOCGETHT, ht); /* get header/trailer sizes */
		lnhsiz = ht[0];
		lntsiz = ht[1];
		ioctl (fd, NIOCGETHOST, &mymach); /* get my in addr */
		signal (SIGAIO, net_intrpt);
	}
	frgsiz.f_name = fhost;
	ioctl (fd, NIONWRITE, &frgsiz);	/* get max. frag size */
	in_frgbuf[fd].fg_size = frgsiz.f_size & ~(FRAGGRAIN - 1);
	in_frgbuf[fd].fg_buf = in_alloc (frgsiz.f_size - sizeof(struct ip), 0);
	return (fd);
}