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assign SCCS numbers for ``June'' beta tape; not yet tested.
[unix-history] / usr / src / sys / netccitt / hd_input.c
/*
* Copyright (c) University of British Columbia, 1984
* Copyright (c) 1990 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.
*
* %sccs.include.redist.c%
*
* @(#)hd_input.c 7.3 (Berkeley) %G%
*/
#include "../h/param.h"
#include "../h/systm.h"
#include "../h/mbuf.h"
#include "../h/domain.h"
#include "../h/socket.h"
#include "../h/protosw.h"
#include "../h/errno.h"
#include "../h/time.h"
#include "../h/kernel.h"
#include "../net/if.h"
#include "../netccitt/hdlc.h"
#include "../netccitt/hd_var.h"
#include "../netccitt/x25.h"
/*
* 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_DEQUEUEIF(&hdintrq, m, ifp);
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;
}
/*
* 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_xcp);
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_xcp);
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_xcp);
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_xcp);
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_xcp);
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_xcp);
#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_xcp);
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);
}
/*
* This section tests the IFRAME for proper sequence. That is, it's
* sequence number N(S) MUST be equal to V(S).
*/
if (ns != hdp->hd_vr) {
hdp->hd_invalid_ns++;
if (pf || (hdp->hd_condition & REJ_CONDITION) == 0) {
hdp->hd_condition |= REJ_CONDITION;
/*
* Flush the transmit queue. This is ugly but we
* have no choice. A reject response must be
* immediately sent to the DCE. Failure to do so
* may result in another out of sequence iframe
* arriving (and thus sending another reject)
* before the first reject is transmitted. This
* will cause the DCE to receive two or more
* rejects back to back, which must never happen.
*/
hd_flush (hdp->hd_ifp);
hd_writeinternal (hdp, REJ, pf);
}
return (queued);
}
hdp->hd_condition &= ~REJ_CONDITION;
/*
* This section finally tests the IFRAME's sequence number against
* the window size (K) and the sequence number of the last frame
* we have acknowledged. If the IFRAME is completely correct then
* it is queued for the packet level.
*/
if (ns != (hdp->hd_lasttxnr + hdp->hd_xcp->xc_lwsize) % MODULUS) {
hdp->hd_vr = (hdp->hd_vr + 1) % MODULUS;
if (pf == 1) {
/* Must generate a RR or RNR with final bit on. */
hd_writeinternal (hdp, RR, POLLON);
} else
/*
* Hopefully we can piggyback the RR, if not we will generate
* a RR when T3 timer expires.
*/
if (hdp -> hd_rrtimer == 0)
hdp->hd_rrtimer = hd_t3;
/* Forward iframe to packet level of X.25. */
fbuf -> m_data += HDHEADERLN;
fbuf -> m_len -= HDHEADERLN;
#ifdef BSD4_3
fbuf->m_act = 0; /* probably not necessary */
#else
{
register struct mbuf *m;
for (m = fbuf; m -> m_next; m = m -> m_next)
m -> m_act = (struct mbuf *) 0;
m -> m_act = (struct mbuf *) 1;
}
#endif
pk_input (fbuf, hdp->hd_xcp);
queued = TRUE;
hd_start (hdp);
} else {
/*
* Here if the remote station has transmitted more iframes then
* the number which have been acknowledged plus K.
*/
hdp->hd_invalid_ns++;
frame_reject (hdp, W, frame);
}
return (queued);
}
/*
* This routine is used to determine if a value (the middle parameter)
* is between two other values. The low value is the first parameter
* the high value is the last parameter. The routine checks the middle
* value to see if it is within the range of the first and last values.
* The reason we need this routine is the values are modulo some base
* hence a simple test for greater or less than is not sufficient.
*/
bool
range_check (rear, value, front)
int rear,
value,
front;
{
register bool result = FALSE;
if (front > rear)
result = (rear <= value) && (value <= front);
else
result = (rear <= value) || (value <= front);
return (result);
}
/*
* This routine handles all the frame reject conditions which can
* arise as a result of secondary processing. The frame reject
* condition Y (frame length error) are handled elsewhere.
*/
static
frame_reject (hdp, rejectcode, frame)
struct hdcb *hdp;
struct Hdlc_iframe *frame;
{
register struct Frmr_frame *frmr = &hd_frmr;
frmr -> frmr_control = ((struct Hdlc_frame *) frame) -> control;
frmr -> frmr_ns = frame -> ns;
frmr -> frmr_f1_0 = 0;
frmr -> frmr_nr = frame -> nr;
frmr -> frmr_f2_0 = 0;
frmr -> frmr_0000 = 0;
frmr -> frmr_w = frmr -> frmr_x = frmr -> frmr_y =
frmr -> frmr_z = 0;
switch (rejectcode) {
case Z:
frmr -> frmr_z = 1;/* invalid N(R). */
break;
case Y:
frmr -> frmr_y = 1;/* iframe length error. */
break;
case X:
frmr -> frmr_x = 1;/* invalid information field. */
frmr -> frmr_w = 1;
break;
case W:
frmr -> frmr_w = 1;/* invalid N(S). */
}
hd_writeinternal (hdp, FRMR, POLLOFF);
hdp->hd_state = WAIT_SABM;
SET_TIMER (hdp);
}
/*
* This procedure is invoked when ever we receive a supervisor
* frame such as RR, RNR and REJ. All processing for these
* frames is done here.
*/
process_sframe (hdp, frame, frametype)
register struct hdcb *hdp;
register struct Hdlc_sframe *frame;
int frametype;
{
register int nr = frame -> nr, pf = frame -> pf, pollbit = 0;
if (valid_nr (hdp, nr, pf) == TRUE) {
switch (frametype) {
case RR:
hdp->hd_condition &= ~REMOTE_RNR_CONDITION;
break;
case RNR:
hdp->hd_condition |= REMOTE_RNR_CONDITION;
hdp->hd_retxcnt = 0;
break;
case REJ:
hdp->hd_condition &= ~REMOTE_RNR_CONDITION;
rej_routine (hdp, nr);
}
if (pf == 1) {
hdp->hd_retxcnt = 0;
hdp->hd_condition &= ~TIMER_RECOVERY_CONDITION;
/* If any iframes have been queued because of the
timer condition, transmit then now. */
if (hdp->hd_condition & REMOTE_RNR_CONDITION) {
/* Remote is busy or timer condition, so only
send one. */
if (hdp->hd_vs != hdp->hd_retxqi)
hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], pollbit);
}
else /* Flush the retransmit list first. */
while (hdp->hd_vs != hdp->hd_retxqi)
hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], POLLOFF);
}
hd_start (hdp);
} else
frame_reject (hdp, Z, (struct Hdlc_iframe *)frame); /* Invalid N(R). */
}
/*
* This routine tests the validity of the N(R) which we have received.
* If it is ok, then all the iframes which it acknowledges (if any)
* will be freed.
*/
bool
valid_nr (hdp, nr, finalbit)
register struct hdcb *hdp;
register int finalbit;
{
/* Make sure it really does acknowledge something. */
if (hdp->hd_lastrxnr == nr)
return (TRUE);
/*
* This section validates the frame's N(R) value. It's N(R) value
* must be in syncronization with our V(S) value and our "last
* received nr" variable. If it is correct then we are able to send
* more IFRAME's, else frame reject condition is entered.
*/
if (range_check (hdp->hd_lastrxnr, nr, hdp->hd_vs) == FALSE) {
if ((hdp->hd_condition & TIMER_RECOVERY_CONDITION) &&
range_check (hdp->hd_vs, nr, hdp->hd_xx) == TRUE)
hdp->hd_vs = nr;
else {
hdp->hd_invalid_nr++;
return (FALSE);
}
}
/*
* If we get to here, we do have a valid frame but it might be out
* of sequence. However, we should still accept the receive state
* number N(R) since it has already passed our previous test and it
* does acknowledge frames which we are sending.
*/
KILL_TIMER (hdp);
free_iframes (hdp, &nr, finalbit);/* Free all acknowledged iframes */
if (nr != hdp->hd_vs)
SET_TIMER (hdp);
return (TRUE);
}
/*
* This routine determines how many iframes need to be retransmitted.
* It then resets the Send State Variable V(S) to accomplish this.
*/
static
rej_routine (hdp, rejnr)
register struct hdcb *hdp;
register int rejnr;
{
register int anchor;
/*
* Flush the output queue. Any iframes queued for
* transmission will be out of sequence.
*/
hd_flush (hdp->hd_ifp);
/*
* Determine how many frames should be re-transmitted. In the case
* of a normal REJ this should be 1 to K. In the case of a timer
* recovery REJ (ie. a REJ with the Final Bit on) this could be 0.
*/
anchor = hdp->hd_vs;
if (hdp->hd_condition & TIMER_RECOVERY_CONDITION)
anchor = hdp->hd_xx;
anchor = (anchor - rejnr + 8) % MODULUS;
if (anchor > 0) {
/* There is at least one iframe to retransmit. */
KILL_TIMER (hdp);
hdp->hd_vs = rejnr;
while (hdp->hd_vs != hdp->hd_retxqi)
hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], POLLOFF);
}
hd_start (hdp);
}
/*
* This routine frees iframes from the retransmit queue. It is called
* when a previously written iframe is acknowledged.
*/
static
free_iframes (hdp, nr, finalbit)
register struct hdcb *hdp;
int *nr;
register int finalbit;
{
register int i, k;
/*
* We need to do the following because of a funny quirk in the
* protocol. This case occures when in Timer recovery condition
* we get a N(R) which acknowledges all the outstanding iframes
* but with the Final Bit off. In this case we need to save the last
* iframe for possible retransmission even though it has already been
* acknowledged!
*/
if ((hdp->hd_condition & TIMER_RECOVERY_CONDITION) && *nr == hdp->hd_xx && finalbit == 0) {
*nr = (*nr - 1 + 8) % MODULUS;
/* printf ("QUIRK\n"); */
}
k = (*nr - hdp->hd_lastrxnr + 8) % MODULUS;
/* Loop here freeing all acknowledged iframes. */
for (i = 0; i < k; ++i) {
m_freem (hdp->hd_retxq[hdp->hd_lastrxnr]);
hdp->hd_retxq[hdp->hd_lastrxnr] = 0;
hdp->hd_lastrxnr = (hdp->hd_lastrxnr + 1) % MODULUS;
}
}
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.