hd_input.c

早期freebsd实现

/*
 * Copyright (c) University of British Columbia, 1984
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Laboratory for Computation Vision and the Computer Science Department
 * of the University of British Columbia.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)hd_input.c	8.1 (Berkeley) 6/10/93
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/socket.h>
#include <sys/protosw.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>

#include <net/if.h>

#include <netccitt/hdlc.h>
#include <netccitt/hd_var.h>
#include <netccitt/x25.h>

static frame_reject();
static rej_routine();
static free_iframes();
/*
 *      HDLC INPUT INTERFACE
 *
 *      This routine is called when the HDLC physical device has
 *      completed reading a frame.
 */

hdintr ()
{
	register struct mbuf *m;
	register struct hdcb *hdp;
	register struct ifnet *ifp;
	register int s;
	static struct ifnet *lastifp;
	static struct hdcb *lasthdp;

	for (;;) {
		s = splimp ();
		IF_DEQUEUE (&hdintrq, m);
		splx (s);
		if (m == 0)
			break;
		if (m->m_len < HDHEADERLN) {
			printf ("hdintr: packet too short (len=%d)\n",
				m->m_len);
			m_freem (m);
			continue;
		}
		if ((m->m_flags & M_PKTHDR) == 0)
			panic("hdintr");
		ifp = m->m_pkthdr.rcvif;

		/*
		 * look up the appropriate hdlc control block
		 */

		if (ifp == lastifp)
			hdp = lasthdp;
		else {
			for (hdp = hdcbhead; hdp; hdp = hdp->hd_next)
				if (hdp->hd_ifp == ifp)
					break;
			if (hdp == 0) {
				printf ("hdintr: unknown interface %x\n", ifp);
				m_freem (m);
				continue;
			}
			lastifp = ifp;
			lasthdp = hdp;
		}

		/* Process_rxframe returns FALSE if the frame was NOT queued
		   for the next higher layers. */
		if (process_rxframe (hdp, m) == FALSE)
			m_freem (m);
	}
}

process_rxframe (hdp, fbuf)
register struct hdcb *hdp;
register struct mbuf *fbuf;
{
	register int queued = FALSE, frametype, pf;
	register struct Hdlc_frame *frame;

	frame = mtod (fbuf, struct Hdlc_frame *);
	pf = ((struct Hdlc_iframe *) frame) -> pf;

	hd_trace (hdp, RX, frame);
	if (frame -> address != ADDRESS_A && frame -> address != ADDRESS_B)
		return (queued);

	switch ((frametype = hd_decode (hdp, frame)) + hdp->hd_state) {
	case DM + DISC_SENT:
	case UA + DISC_SENT:
		/*
		 * Link now closed.  Leave timer running
		 * so hd_timer() can periodically check the
		 * status of interface driver flag bit IFF_UP.
		 */
		hdp->hd_state = DISCONNECTED;
		break;

	case DM + INIT:
	case UA + INIT:
		/*
		 * This is a non-standard state change needed for DCEs
		 * that do dynamic link selection.  We can't go into the
		 * usual "SEND DM" state because a DM is a SARM in LAP.
		 */
		hd_writeinternal (hdp, SABM, POLLOFF);
		hdp->hd_state = SABM_SENT;
		SET_TIMER (hdp);
		break;

	case SABM + DM_SENT: 
	case SABM + WAIT_SABM: 
		hd_writeinternal (hdp, UA, pf);
	case UA + SABM_SENT: 
	case UA + WAIT_UA: 
		KILL_TIMER (hdp);
		hd_initvars (hdp);
		hdp->hd_state = ABM;
		hd_message (hdp, "Link level operational");
		/* Notify the packet level - to send RESTART. */
		(void) pk_ctlinput (PRC_LINKUP, hdp->hd_pkp);
		break;

	case SABM + SABM_SENT: 
		/* Got a SABM collision. Acknowledge the remote's SABM
		   via UA but still wait for UA. */
		hd_writeinternal (hdp, UA, pf);
		break;

	case SABM + ABM: 
		/* Request to reset the link from the remote. */
		KILL_TIMER (hdp);
		hd_message (hdp, "Link reset");
#ifdef HDLCDEBUG
		hd_dumptrace (hdp);
#endif
		hd_flush (hdp->hd_ifp);
		hd_writeinternal (hdp, UA, pf);
		hd_initvars (hdp);
		(void) pk_ctlinput (PRC_LINKRESET, hdp->hd_pkp);
		hdp->hd_resets++;
		break;

	case SABM + WAIT_UA: 
		hd_writeinternal (hdp, UA, pf);
		break;

	case DM + ABM: 
		hd_message (hdp, "DM received: link down");
#ifdef HDLCDEBUG
		hd_dumptrace (hdp);
#endif
		(void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp);
		hd_flush (hdp->hd_ifp);
	case DM + DM_SENT: 
	case DM + WAIT_SABM: 
	case DM + WAIT_UA: 
		hd_writeinternal (hdp, SABM, pf);
		hdp->hd_state = SABM_SENT;
		SET_TIMER (hdp);
		break;

	case DISC + INIT:
	case DISC + DM_SENT: 
	case DISC + SABM_SENT: 
		/* Note: This is a non-standard state change. */
		hd_writeinternal (hdp, UA, pf);
		hd_writeinternal (hdp, SABM, POLLOFF);
		hdp->hd_state = SABM_SENT;
		SET_TIMER (hdp);
		break;

	case DISC + WAIT_UA: 
		hd_writeinternal (hdp, DM, pf);
		SET_TIMER (hdp);
		hdp->hd_state = DM_SENT;
		break;

	case DISC + ABM: 
		hd_message (hdp, "DISC received: link down");
		(void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp);
	case DISC + WAIT_SABM: 
		hd_writeinternal (hdp, UA, pf);
		hdp->hd_state = DM_SENT;
		SET_TIMER (hdp);
		break;

	case UA + ABM: 
		hd_message (hdp, "UA received: link down");
		(void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp);
	case UA + WAIT_SABM: 
		hd_writeinternal (hdp, DM, pf);
		hdp->hd_state = DM_SENT;
		SET_TIMER (hdp);
		break;

	case FRMR + DM_SENT: 
		hd_writeinternal (hdp, SABM, pf);
		hdp->hd_state = SABM_SENT;
		SET_TIMER (hdp);
		break;

	case FRMR + WAIT_SABM: 
		hd_writeinternal (hdp, DM, pf);
		hdp->hd_state = DM_SENT;
		SET_TIMER (hdp);
		break;

	case FRMR + ABM: 
		hd_message (hdp, "FRMR received: link down");
		(void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp);
#ifdef HDLCDEBUG
		hd_dumptrace (hdp);
#endif
		hd_flush (hdp->hd_ifp);
		hd_writeinternal (hdp, SABM, pf);
		hdp->hd_state = WAIT_UA;
		SET_TIMER (hdp);
		break;

	case RR + ABM: 
	case RNR + ABM: 
	case REJ + ABM: 
		process_sframe (hdp, (struct Hdlc_sframe *)frame, frametype);
		break;

	case IFRAME + ABM: 
		queued = process_iframe (hdp, fbuf, (struct Hdlc_iframe *)frame);
		break;

	case IFRAME + SABM_SENT: 
	case RR + SABM_SENT: 
	case RNR + SABM_SENT: 
	case REJ + SABM_SENT: 
		hd_writeinternal (hdp, DM, POLLON);
		hdp->hd_state = DM_SENT;
		SET_TIMER (hdp);
		break;

	case IFRAME + WAIT_SABM: 
	case RR + WAIT_SABM: 
	case RNR + WAIT_SABM: 
	case REJ + WAIT_SABM: 
		hd_writeinternal (hdp, FRMR, POLLOFF);
		SET_TIMER (hdp);
		break;

	case ILLEGAL + SABM_SENT: 
		hdp->hd_unknown++;
		hd_writeinternal (hdp, DM, POLLOFF);
		hdp->hd_state = DM_SENT;
		SET_TIMER (hdp);
		break;

	case ILLEGAL + ABM: 
		hd_message (hdp, "Unknown frame received: link down");
		(void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp);
	case ILLEGAL + WAIT_SABM:
		hdp->hd_unknown++;
#ifdef HDLCDEBUG
		hd_dumptrace (hdp);
#endif
		hd_writeinternal (hdp, FRMR, POLLOFF);
		hdp->hd_state = WAIT_SABM;
		SET_TIMER (hdp);
		break;
	}

	return (queued);
}

process_iframe (hdp, fbuf, frame)
register struct hdcb *hdp;
struct mbuf *fbuf;
register struct Hdlc_iframe *frame;
{
	register int    nr = frame -> nr,
	                ns = frame -> ns,
	                pf = frame -> pf;
	register int    queued = FALSE;

	/* 
	 *  Validate the iframe's N(R) value. It's N(R) value must be in
	 *   sync with our V(S) value and our "last received nr".
	 */

	if (valid_nr (hdp, nr, FALSE) == FALSE) {
		frame_reject (hdp, Z, frame);
		return (queued);
	}