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21e3a7bd KS |
1 | /* |
2 | * Copyright (c) University of British Columbia, 1984 | |
3 | * Copyright (c) 1990 The Regents of the University of California. | |
4 | * All rights reserved. | |
5 | * | |
6 | * This code is derived from software contributed to Berkeley by | |
7 | * the Laboratory for Computation Vision and the Computer Science Department | |
8 | * of the University of British Columbia. | |
9 | * | |
af359dea C |
10 | * Redistribution and use in source and binary forms, with or without |
11 | * modification, are permitted provided that the following conditions | |
12 | * are met: | |
13 | * 1. Redistributions of source code must retain the above copyright | |
14 | * notice, this list of conditions and the following disclaimer. | |
15 | * 2. Redistributions in binary form must reproduce the above copyright | |
16 | * notice, this list of conditions and the following disclaimer in the | |
17 | * documentation and/or other materials provided with the distribution. | |
18 | * 3. All advertising materials mentioning features or use of this software | |
19 | * must display the following acknowledgement: | |
20 | * This product includes software developed by the University of | |
21 | * California, Berkeley and its contributors. | |
22 | * 4. Neither the name of the University nor the names of its contributors | |
23 | * may be used to endorse or promote products derived from this software | |
24 | * without specific prior written permission. | |
21e3a7bd | 25 | * |
af359dea C |
26 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
27 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
28 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
29 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
30 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
31 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
32 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
33 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
34 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
35 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
36 | * SUCH DAMAGE. | |
37 | * | |
38 | * @(#)hd_input.c 7.7 (Berkeley) 5/29/91 | |
21e3a7bd | 39 | */ |
0f9bb9b6 | 40 | |
4507dea2 KS |
41 | #include "param.h" |
42 | #include "systm.h" | |
43 | #include "mbuf.h" | |
44 | #include "domain.h" | |
45 | #include "socket.h" | |
46 | #include "protosw.h" | |
47 | #include "errno.h" | |
48 | #include "time.h" | |
49 | #include "kernel.h" | |
0f9bb9b6 KS |
50 | |
51 | #include "../net/if.h" | |
52 | ||
4507dea2 KS |
53 | #include "hdlc.h" |
54 | #include "hd_var.h" | |
55 | #include "x25.h" | |
0f9bb9b6 KS |
56 | |
57 | /* | |
58 | * HDLC INPUT INTERFACE | |
59 | * | |
60 | * This routine is called when the HDLC physical device has | |
61 | * completed reading a frame. | |
62 | */ | |
63 | ||
64 | hdintr () | |
65 | { | |
66 | register struct mbuf *m; | |
67 | register struct hdcb *hdp; | |
68 | register struct ifnet *ifp; | |
69 | register int s; | |
42963956 | 70 | extern struct ifqueue pkintrq; |
0f9bb9b6 KS |
71 | static struct ifnet *lastifp; |
72 | static struct hdcb *lasthdp; | |
73 | ||
74 | for (;;) { | |
75 | s = splimp (); | |
42963956 | 76 | IF_DEQUEUE (&hdintrq, m); |
0f9bb9b6 KS |
77 | splx (s); |
78 | if (m == 0) | |
79 | break; | |
80 | if (m->m_len < HDHEADERLN) { | |
81 | printf ("hdintr: packet too short (len=%d)\n", | |
82 | m->m_len); | |
83 | m_freem (m); | |
84 | continue; | |
85 | } | |
42963956 KS |
86 | if ((m->m_flags & M_PKTHDR) == 0) |
87 | panic("hdintr"); | |
88 | ifp = m->m_pkthdr.rcvif; | |
0f9bb9b6 KS |
89 | |
90 | /* | |
91 | * look up the appropriate hdlc control block | |
92 | */ | |
93 | ||
94 | if (ifp == lastifp) | |
95 | hdp = lasthdp; | |
96 | else { | |
97 | for (hdp = hdcbhead; hdp; hdp = hdp->hd_next) | |
98 | if (hdp->hd_ifp == ifp) | |
99 | break; | |
100 | if (hdp == 0) { | |
101 | printf ("hdintr: unknown interface %x\n", ifp); | |
102 | m_freem (m); | |
103 | continue; | |
104 | } | |
105 | lastifp = ifp; | |
106 | lasthdp = hdp; | |
107 | } | |
108 | ||
109 | /* Process_rxframe returns FALSE if the frame was NOT queued | |
110 | for the next higher layers. */ | |
111 | if (process_rxframe (hdp, m) == FALSE) | |
112 | m_freem (m); | |
113 | } | |
42963956 KS |
114 | if (pkintrq.ifq_len) |
115 | pkintr (); | |
0f9bb9b6 KS |
116 | } |
117 | ||
118 | process_rxframe (hdp, fbuf) | |
119 | register struct hdcb *hdp; | |
120 | register struct mbuf *fbuf; | |
121 | { | |
122 | register int queued = FALSE, frametype, pf; | |
123 | register struct Hdlc_frame *frame; | |
124 | ||
125 | frame = mtod (fbuf, struct Hdlc_frame *); | |
126 | pf = ((struct Hdlc_iframe *) frame) -> pf; | |
127 | ||
128 | hd_trace (hdp, RX, frame); | |
129 | if (frame -> address != ADDRESS_A && frame -> address != ADDRESS_B) | |
130 | return (queued); | |
131 | ||
132 | switch ((frametype = hd_decode (hdp, frame)) + hdp->hd_state) { | |
133 | case DM + DISC_SENT: | |
134 | case UA + DISC_SENT: | |
135 | /* | |
136 | * Link now closed. Leave timer running | |
137 | * so hd_timer() can periodically check the | |
138 | * status of interface driver flag bit IFF_UP. | |
139 | */ | |
140 | hdp->hd_state = DISCONNECTED; | |
141 | break; | |
142 | ||
143 | case DM + INIT: | |
144 | case UA + INIT: | |
145 | /* | |
146 | * This is a non-standard state change needed for DCEs | |
147 | * that do dynamic link selection. We can't go into the | |
148 | * usual "SEND DM" state because a DM is a SARM in LAP. | |
149 | */ | |
150 | hd_writeinternal (hdp, SABM, POLLOFF); | |
151 | hdp->hd_state = SABM_SENT; | |
152 | SET_TIMER (hdp); | |
153 | break; | |
154 | ||
155 | case SABM + DM_SENT: | |
156 | case SABM + WAIT_SABM: | |
157 | hd_writeinternal (hdp, UA, pf); | |
158 | case UA + SABM_SENT: | |
159 | case UA + WAIT_UA: | |
160 | KILL_TIMER (hdp); | |
161 | hd_initvars (hdp); | |
162 | hdp->hd_state = ABM; | |
163 | hd_message (hdp, "Link level operational"); | |
164 | /* Notify the packet level - to send RESTART. */ | |
af359dea | 165 | (void) pk_ctlinput (PRC_LINKUP, hdp->hd_pkp); |
0f9bb9b6 KS |
166 | break; |
167 | ||
168 | case SABM + SABM_SENT: | |
169 | /* Got a SABM collision. Acknowledge the remote's SABM | |
170 | via UA but still wait for UA. */ | |
171 | hd_writeinternal (hdp, UA, pf); | |
172 | break; | |
173 | ||
174 | case SABM + ABM: | |
175 | /* Request to reset the link from the remote. */ | |
176 | KILL_TIMER (hdp); | |
177 | hd_message (hdp, "Link reset"); | |
178 | #ifdef HDLCDEBUG | |
179 | hd_dumptrace (hdp); | |
180 | #endif | |
181 | hd_flush (hdp->hd_ifp); | |
182 | hd_writeinternal (hdp, UA, pf); | |
183 | hd_initvars (hdp); | |
af359dea | 184 | (void) pk_ctlinput (PRC_LINKRESET, hdp->hd_pkp); |
0f9bb9b6 KS |
185 | hdp->hd_resets++; |
186 | break; | |
187 | ||
188 | case SABM + WAIT_UA: | |
189 | hd_writeinternal (hdp, UA, pf); | |
190 | break; | |
191 | ||
192 | case DM + ABM: | |
193 | hd_message (hdp, "DM received: link down"); | |
194 | #ifdef HDLCDEBUG | |
195 | hd_dumptrace (hdp); | |
196 | #endif | |
af359dea | 197 | (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp); |
0f9bb9b6 KS |
198 | hd_flush (hdp->hd_ifp); |
199 | case DM + DM_SENT: | |
200 | case DM + WAIT_SABM: | |
201 | case DM + WAIT_UA: | |
202 | hd_writeinternal (hdp, SABM, pf); | |
203 | hdp->hd_state = SABM_SENT; | |
204 | SET_TIMER (hdp); | |
205 | break; | |
206 | ||
207 | case DISC + INIT: | |
208 | case DISC + DM_SENT: | |
209 | case DISC + SABM_SENT: | |
210 | /* Note: This is a non-standard state change. */ | |
211 | hd_writeinternal (hdp, UA, pf); | |
212 | hd_writeinternal (hdp, SABM, POLLOFF); | |
213 | hdp->hd_state = SABM_SENT; | |
214 | SET_TIMER (hdp); | |
215 | break; | |
216 | ||
217 | case DISC + WAIT_UA: | |
218 | hd_writeinternal (hdp, DM, pf); | |
219 | SET_TIMER (hdp); | |
220 | hdp->hd_state = DM_SENT; | |
221 | break; | |
222 | ||
223 | case DISC + ABM: | |
224 | hd_message (hdp, "DISC received: link down"); | |
af359dea | 225 | (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp); |
0f9bb9b6 KS |
226 | case DISC + WAIT_SABM: |
227 | hd_writeinternal (hdp, UA, pf); | |
228 | hdp->hd_state = DM_SENT; | |
229 | SET_TIMER (hdp); | |
230 | break; | |
231 | ||
232 | case UA + ABM: | |
233 | hd_message (hdp, "UA received: link down"); | |
af359dea | 234 | (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp); |
0f9bb9b6 KS |
235 | case UA + WAIT_SABM: |
236 | hd_writeinternal (hdp, DM, pf); | |
237 | hdp->hd_state = DM_SENT; | |
238 | SET_TIMER (hdp); | |
239 | break; | |
240 | ||
241 | case FRMR + DM_SENT: | |
242 | hd_writeinternal (hdp, SABM, pf); | |
243 | hdp->hd_state = SABM_SENT; | |
244 | SET_TIMER (hdp); | |
245 | break; | |
246 | ||
247 | case FRMR + WAIT_SABM: | |
248 | hd_writeinternal (hdp, DM, pf); | |
249 | hdp->hd_state = DM_SENT; | |
250 | SET_TIMER (hdp); | |
251 | break; | |
252 | ||
253 | case FRMR + ABM: | |
254 | hd_message (hdp, "FRMR received: link down"); | |
af359dea | 255 | (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp); |
0f9bb9b6 KS |
256 | #ifdef HDLCDEBUG |
257 | hd_dumptrace (hdp); | |
258 | #endif | |
259 | hd_flush (hdp->hd_ifp); | |
260 | hd_writeinternal (hdp, SABM, pf); | |
261 | hdp->hd_state = WAIT_UA; | |
262 | SET_TIMER (hdp); | |
263 | break; | |
264 | ||
265 | case RR + ABM: | |
266 | case RNR + ABM: | |
267 | case REJ + ABM: | |
268 | process_sframe (hdp, (struct Hdlc_sframe *)frame, frametype); | |
269 | break; | |
270 | ||
271 | case IFRAME + ABM: | |
272 | queued = process_iframe (hdp, fbuf, (struct Hdlc_iframe *)frame); | |
273 | break; | |
274 | ||
275 | case IFRAME + SABM_SENT: | |
276 | case RR + SABM_SENT: | |
277 | case RNR + SABM_SENT: | |
278 | case REJ + SABM_SENT: | |
279 | hd_writeinternal (hdp, DM, POLLON); | |
280 | hdp->hd_state = DM_SENT; | |
281 | SET_TIMER (hdp); | |
282 | break; | |
283 | ||
284 | case IFRAME + WAIT_SABM: | |
285 | case RR + WAIT_SABM: | |
286 | case RNR + WAIT_SABM: | |
287 | case REJ + WAIT_SABM: | |
288 | hd_writeinternal (hdp, FRMR, POLLOFF); | |
289 | SET_TIMER (hdp); | |
290 | break; | |
291 | ||
292 | case ILLEGAL + SABM_SENT: | |
293 | hdp->hd_unknown++; | |
294 | hd_writeinternal (hdp, DM, POLLOFF); | |
295 | hdp->hd_state = DM_SENT; | |
296 | SET_TIMER (hdp); | |
297 | break; | |
298 | ||
299 | case ILLEGAL + ABM: | |
300 | hd_message (hdp, "Unknown frame received: link down"); | |
af359dea | 301 | (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp); |
0f9bb9b6 KS |
302 | case ILLEGAL + WAIT_SABM: |
303 | hdp->hd_unknown++; | |
304 | #ifdef HDLCDEBUG | |
305 | hd_dumptrace (hdp); | |
306 | #endif | |
307 | hd_writeinternal (hdp, FRMR, POLLOFF); | |
308 | hdp->hd_state = WAIT_SABM; | |
309 | SET_TIMER (hdp); | |
310 | break; | |
311 | } | |
312 | ||
313 | return (queued); | |
314 | } | |
315 | ||
316 | process_iframe (hdp, fbuf, frame) | |
317 | register struct hdcb *hdp; | |
318 | struct mbuf *fbuf; | |
319 | register struct Hdlc_iframe *frame; | |
320 | { | |
321 | register int nr = frame -> nr, | |
322 | ns = frame -> ns, | |
323 | pf = frame -> pf; | |
324 | register int queued = FALSE; | |
325 | ||
326 | /* | |
327 | * Validate the iframe's N(R) value. It's N(R) value must be in | |
328 | * sync with our V(S) value and our "last received nr". | |
329 | */ | |
330 | ||
331 | if (valid_nr (hdp, nr, FALSE) == FALSE) { | |
332 | frame_reject (hdp, Z, frame); | |
333 | return (queued); | |
334 | } | |
335 | ||
336 | ||
337 | /* | |
338 | * This section tests the IFRAME for proper sequence. That is, it's | |
339 | * sequence number N(S) MUST be equal to V(S). | |
340 | */ | |
341 | ||
342 | if (ns != hdp->hd_vr) { | |
343 | hdp->hd_invalid_ns++; | |
344 | if (pf || (hdp->hd_condition & REJ_CONDITION) == 0) { | |
345 | hdp->hd_condition |= REJ_CONDITION; | |
346 | /* | |
347 | * Flush the transmit queue. This is ugly but we | |
348 | * have no choice. A reject response must be | |
349 | * immediately sent to the DCE. Failure to do so | |
350 | * may result in another out of sequence iframe | |
351 | * arriving (and thus sending another reject) | |
352 | * before the first reject is transmitted. This | |
353 | * will cause the DCE to receive two or more | |
354 | * rejects back to back, which must never happen. | |
355 | */ | |
356 | hd_flush (hdp->hd_ifp); | |
357 | hd_writeinternal (hdp, REJ, pf); | |
358 | } | |
359 | return (queued); | |
360 | } | |
361 | hdp->hd_condition &= ~REJ_CONDITION; | |
362 | ||
363 | /* | |
364 | * This section finally tests the IFRAME's sequence number against | |
365 | * the window size (K) and the sequence number of the last frame | |
366 | * we have acknowledged. If the IFRAME is completely correct then | |
367 | * it is queued for the packet level. | |
368 | */ | |
369 | ||
af359dea C |
370 | if (ns != (hdp -> hd_lasttxnr + hdp -> hd_xcp -> xc_lwsize) % MODULUS) { |
371 | hdp -> hd_vr = (hdp -> hd_vr + 1) % MODULUS; | |
0f9bb9b6 KS |
372 | if (pf == 1) { |
373 | /* Must generate a RR or RNR with final bit on. */ | |
374 | hd_writeinternal (hdp, RR, POLLON); | |
375 | } else | |
376 | /* | |
377 | * Hopefully we can piggyback the RR, if not we will generate | |
378 | * a RR when T3 timer expires. | |
379 | */ | |
380 | if (hdp -> hd_rrtimer == 0) | |
381 | hdp->hd_rrtimer = hd_t3; | |
382 | ||
383 | /* Forward iframe to packet level of X.25. */ | |
b84e7ca8 | 384 | fbuf -> m_data += HDHEADERLN; |
0f9bb9b6 | 385 | fbuf -> m_len -= HDHEADERLN; |
761493c1 | 386 | fbuf -> m_pkthdr.len -= HDHEADERLN; |
af359dea | 387 | fbuf -> m_pkthdr.rcvif = (struct ifnet *)hdp -> hd_pkp; |
0f9bb9b6 KS |
388 | #ifdef BSD4_3 |
389 | fbuf->m_act = 0; /* probably not necessary */ | |
390 | #else | |
391 | { | |
392 | register struct mbuf *m; | |
393 | ||
394 | for (m = fbuf; m -> m_next; m = m -> m_next) | |
395 | m -> m_act = (struct mbuf *) 0; | |
396 | m -> m_act = (struct mbuf *) 1; | |
397 | } | |
398 | #endif | |
af359dea | 399 | pk_input (fbuf); |
0f9bb9b6 KS |
400 | queued = TRUE; |
401 | hd_start (hdp); | |
402 | } else { | |
403 | /* | |
404 | * Here if the remote station has transmitted more iframes then | |
405 | * the number which have been acknowledged plus K. | |
406 | */ | |
407 | hdp->hd_invalid_ns++; | |
408 | frame_reject (hdp, W, frame); | |
409 | } | |
410 | return (queued); | |
411 | } | |
412 | ||
413 | /* | |
414 | * This routine is used to determine if a value (the middle parameter) | |
415 | * is between two other values. The low value is the first parameter | |
416 | * the high value is the last parameter. The routine checks the middle | |
417 | * value to see if it is within the range of the first and last values. | |
418 | * The reason we need this routine is the values are modulo some base | |
419 | * hence a simple test for greater or less than is not sufficient. | |
420 | */ | |
421 | ||
422 | bool | |
423 | range_check (rear, value, front) | |
424 | int rear, | |
425 | value, | |
426 | front; | |
427 | { | |
428 | register bool result = FALSE; | |
429 | ||
430 | if (front > rear) | |
431 | result = (rear <= value) && (value <= front); | |
432 | else | |
433 | result = (rear <= value) || (value <= front); | |
434 | ||
435 | return (result); | |
436 | } | |
437 | ||
438 | /* | |
439 | * This routine handles all the frame reject conditions which can | |
440 | * arise as a result of secondary processing. The frame reject | |
441 | * condition Y (frame length error) are handled elsewhere. | |
442 | */ | |
443 | ||
444 | static | |
445 | frame_reject (hdp, rejectcode, frame) | |
446 | struct hdcb *hdp; | |
447 | struct Hdlc_iframe *frame; | |
448 | { | |
449 | register struct Frmr_frame *frmr = &hd_frmr; | |
450 | ||
451 | frmr -> frmr_control = ((struct Hdlc_frame *) frame) -> control; | |
452 | ||
453 | frmr -> frmr_ns = frame -> ns; | |
454 | frmr -> frmr_f1_0 = 0; | |
455 | frmr -> frmr_nr = frame -> nr; | |
456 | frmr -> frmr_f2_0 = 0; | |
457 | ||
458 | frmr -> frmr_0000 = 0; | |
459 | frmr -> frmr_w = frmr -> frmr_x = frmr -> frmr_y = | |
460 | frmr -> frmr_z = 0; | |
461 | switch (rejectcode) { | |
462 | case Z: | |
463 | frmr -> frmr_z = 1;/* invalid N(R). */ | |
464 | break; | |
465 | ||
466 | case Y: | |
467 | frmr -> frmr_y = 1;/* iframe length error. */ | |
468 | break; | |
469 | ||
470 | case X: | |
471 | frmr -> frmr_x = 1;/* invalid information field. */ | |
472 | frmr -> frmr_w = 1; | |
473 | break; | |
474 | ||
475 | case W: | |
476 | frmr -> frmr_w = 1;/* invalid N(S). */ | |
477 | } | |
478 | ||
479 | hd_writeinternal (hdp, FRMR, POLLOFF); | |
480 | ||
481 | hdp->hd_state = WAIT_SABM; | |
482 | SET_TIMER (hdp); | |
483 | } | |
484 | ||
485 | /* | |
486 | * This procedure is invoked when ever we receive a supervisor | |
487 | * frame such as RR, RNR and REJ. All processing for these | |
488 | * frames is done here. | |
489 | */ | |
490 | ||
491 | process_sframe (hdp, frame, frametype) | |
492 | register struct hdcb *hdp; | |
493 | register struct Hdlc_sframe *frame; | |
494 | int frametype; | |
495 | { | |
496 | register int nr = frame -> nr, pf = frame -> pf, pollbit = 0; | |
497 | ||
498 | if (valid_nr (hdp, nr, pf) == TRUE) { | |
499 | switch (frametype) { | |
500 | case RR: | |
501 | hdp->hd_condition &= ~REMOTE_RNR_CONDITION; | |
502 | break; | |
503 | ||
504 | case RNR: | |
505 | hdp->hd_condition |= REMOTE_RNR_CONDITION; | |
506 | hdp->hd_retxcnt = 0; | |
507 | break; | |
508 | ||
509 | case REJ: | |
510 | hdp->hd_condition &= ~REMOTE_RNR_CONDITION; | |
511 | rej_routine (hdp, nr); | |
512 | } | |
513 | ||
514 | if (pf == 1) { | |
515 | hdp->hd_retxcnt = 0; | |
516 | hdp->hd_condition &= ~TIMER_RECOVERY_CONDITION; | |
517 | ||
42963956 KS |
518 | if (frametype == RR && hdp->hd_lastrxnr == hdp->hd_vs |
519 | && hdp->hd_timer == 0 && hdp->hd_txq.head == 0) | |
520 | hd_writeinternal(hdp, RR, pf); | |
521 | else | |
0f9bb9b6 KS |
522 | /* If any iframes have been queued because of the |
523 | timer condition, transmit then now. */ | |
524 | if (hdp->hd_condition & REMOTE_RNR_CONDITION) { | |
525 | /* Remote is busy or timer condition, so only | |
526 | send one. */ | |
527 | if (hdp->hd_vs != hdp->hd_retxqi) | |
528 | hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], pollbit); | |
529 | } | |
530 | else /* Flush the retransmit list first. */ | |
531 | while (hdp->hd_vs != hdp->hd_retxqi) | |
532 | hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], POLLOFF); | |
533 | } | |
534 | ||
535 | hd_start (hdp); | |
536 | } else | |
537 | frame_reject (hdp, Z, (struct Hdlc_iframe *)frame); /* Invalid N(R). */ | |
538 | } | |
539 | ||
540 | /* | |
541 | * This routine tests the validity of the N(R) which we have received. | |
542 | * If it is ok, then all the iframes which it acknowledges (if any) | |
543 | * will be freed. | |
544 | */ | |
545 | ||
546 | bool | |
547 | valid_nr (hdp, nr, finalbit) | |
548 | register struct hdcb *hdp; | |
549 | register int finalbit; | |
550 | { | |
551 | /* Make sure it really does acknowledge something. */ | |
552 | if (hdp->hd_lastrxnr == nr) | |
553 | return (TRUE); | |
554 | ||
555 | /* | |
556 | * This section validates the frame's N(R) value. It's N(R) value | |
557 | * must be in syncronization with our V(S) value and our "last | |
558 | * received nr" variable. If it is correct then we are able to send | |
559 | * more IFRAME's, else frame reject condition is entered. | |
560 | */ | |
561 | ||
562 | if (range_check (hdp->hd_lastrxnr, nr, hdp->hd_vs) == FALSE) { | |
563 | if ((hdp->hd_condition & TIMER_RECOVERY_CONDITION) && | |
564 | range_check (hdp->hd_vs, nr, hdp->hd_xx) == TRUE) | |
565 | hdp->hd_vs = nr; | |
566 | ||
567 | else { | |
568 | hdp->hd_invalid_nr++; | |
569 | return (FALSE); | |
570 | } | |
571 | } | |
572 | ||
573 | /* | |
574 | * If we get to here, we do have a valid frame but it might be out | |
575 | * of sequence. However, we should still accept the receive state | |
576 | * number N(R) since it has already passed our previous test and it | |
577 | * does acknowledge frames which we are sending. | |
578 | */ | |
579 | ||
580 | KILL_TIMER (hdp); | |
581 | free_iframes (hdp, &nr, finalbit);/* Free all acknowledged iframes */ | |
582 | if (nr != hdp->hd_vs) | |
583 | SET_TIMER (hdp); | |
584 | ||
585 | return (TRUE); | |
586 | } | |
587 | ||
588 | /* | |
589 | * This routine determines how many iframes need to be retransmitted. | |
590 | * It then resets the Send State Variable V(S) to accomplish this. | |
591 | */ | |
592 | ||
593 | static | |
594 | rej_routine (hdp, rejnr) | |
595 | register struct hdcb *hdp; | |
596 | register int rejnr; | |
597 | { | |
598 | register int anchor; | |
599 | ||
600 | /* | |
601 | * Flush the output queue. Any iframes queued for | |
602 | * transmission will be out of sequence. | |
603 | */ | |
604 | ||
605 | hd_flush (hdp->hd_ifp); | |
606 | ||
607 | /* | |
608 | * Determine how many frames should be re-transmitted. In the case | |
609 | * of a normal REJ this should be 1 to K. In the case of a timer | |
610 | * recovery REJ (ie. a REJ with the Final Bit on) this could be 0. | |
611 | */ | |
612 | ||
613 | anchor = hdp->hd_vs; | |
614 | if (hdp->hd_condition & TIMER_RECOVERY_CONDITION) | |
615 | anchor = hdp->hd_xx; | |
616 | ||
617 | anchor = (anchor - rejnr + 8) % MODULUS; | |
618 | ||
619 | if (anchor > 0) { | |
620 | ||
621 | /* There is at least one iframe to retransmit. */ | |
622 | KILL_TIMER (hdp); | |
623 | hdp->hd_vs = rejnr; | |
624 | ||
625 | while (hdp->hd_vs != hdp->hd_retxqi) | |
626 | hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], POLLOFF); | |
627 | ||
628 | } | |
629 | hd_start (hdp); | |
630 | } | |
631 | ||
632 | /* | |
633 | * This routine frees iframes from the retransmit queue. It is called | |
634 | * when a previously written iframe is acknowledged. | |
635 | */ | |
636 | ||
637 | static | |
638 | free_iframes (hdp, nr, finalbit) | |
639 | register struct hdcb *hdp; | |
640 | int *nr; | |
641 | register int finalbit; | |
642 | ||
643 | { | |
644 | register int i, k; | |
645 | ||
646 | /* | |
647 | * We need to do the following because of a funny quirk in the | |
648 | * protocol. This case occures when in Timer recovery condition | |
649 | * we get a N(R) which acknowledges all the outstanding iframes | |
650 | * but with the Final Bit off. In this case we need to save the last | |
651 | * iframe for possible retransmission even though it has already been | |
652 | * acknowledged! | |
653 | */ | |
654 | ||
655 | if ((hdp->hd_condition & TIMER_RECOVERY_CONDITION) && *nr == hdp->hd_xx && finalbit == 0) { | |
656 | *nr = (*nr - 1 + 8) % MODULUS; | |
657 | /* printf ("QUIRK\n"); */ | |
658 | } | |
659 | ||
660 | k = (*nr - hdp->hd_lastrxnr + 8) % MODULUS; | |
661 | ||
662 | /* Loop here freeing all acknowledged iframes. */ | |
663 | for (i = 0; i < k; ++i) { | |
664 | m_freem (hdp->hd_retxq[hdp->hd_lastrxnr]); | |
665 | hdp->hd_retxq[hdp->hd_lastrxnr] = 0; | |
666 | hdp->hd_lastrxnr = (hdp->hd_lastrxnr + 1) % MODULUS; | |
667 | } | |
668 | ||
669 | } |