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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 | * | |
10 | * %sccs.include.redist.c% | |
11 | * | |
52ffa8dd | 12 | * @(#)hd_input.c 7.9 (Berkeley) %G% |
21e3a7bd | 13 | */ |
0f9bb9b6 | 14 | |
5548a02f KB |
15 | #include <sys/param.h> |
16 | #include <sys/systm.h> | |
17 | #include <sys/mbuf.h> | |
18 | #include <sys/domain.h> | |
19 | #include <sys/socket.h> | |
20 | #include <sys/protosw.h> | |
21 | #include <sys/errno.h> | |
22 | #include <sys/time.h> | |
23 | #include <sys/kernel.h> | |
0f9bb9b6 | 24 | |
5548a02f | 25 | #include <net/if.h> |
0f9bb9b6 | 26 | |
5548a02f KB |
27 | #include <netccitt/hdlc.h> |
28 | #include <netccitt/hd_var.h> | |
29 | #include <netccitt/x25.h> | |
0f9bb9b6 | 30 | |
52ffa8dd KS |
31 | static frame_reject(); |
32 | static rej_routine(); | |
33 | static free_iframes(); | |
0f9bb9b6 KS |
34 | /* |
35 | * HDLC INPUT INTERFACE | |
36 | * | |
37 | * This routine is called when the HDLC physical device has | |
38 | * completed reading a frame. | |
39 | */ | |
40 | ||
41 | hdintr () | |
42 | { | |
43 | register struct mbuf *m; | |
44 | register struct hdcb *hdp; | |
45 | register struct ifnet *ifp; | |
46 | register int s; | |
47 | static struct ifnet *lastifp; | |
48 | static struct hdcb *lasthdp; | |
49 | ||
50 | for (;;) { | |
51 | s = splimp (); | |
42963956 | 52 | IF_DEQUEUE (&hdintrq, m); |
0f9bb9b6 KS |
53 | splx (s); |
54 | if (m == 0) | |
55 | break; | |
56 | if (m->m_len < HDHEADERLN) { | |
57 | printf ("hdintr: packet too short (len=%d)\n", | |
58 | m->m_len); | |
59 | m_freem (m); | |
60 | continue; | |
61 | } | |
42963956 KS |
62 | if ((m->m_flags & M_PKTHDR) == 0) |
63 | panic("hdintr"); | |
64 | ifp = m->m_pkthdr.rcvif; | |
0f9bb9b6 KS |
65 | |
66 | /* | |
67 | * look up the appropriate hdlc control block | |
68 | */ | |
69 | ||
70 | if (ifp == lastifp) | |
71 | hdp = lasthdp; | |
72 | else { | |
73 | for (hdp = hdcbhead; hdp; hdp = hdp->hd_next) | |
74 | if (hdp->hd_ifp == ifp) | |
75 | break; | |
76 | if (hdp == 0) { | |
77 | printf ("hdintr: unknown interface %x\n", ifp); | |
78 | m_freem (m); | |
79 | continue; | |
80 | } | |
81 | lastifp = ifp; | |
82 | lasthdp = hdp; | |
83 | } | |
84 | ||
85 | /* Process_rxframe returns FALSE if the frame was NOT queued | |
86 | for the next higher layers. */ | |
87 | if (process_rxframe (hdp, m) == FALSE) | |
88 | m_freem (m); | |
89 | } | |
90 | } | |
91 | ||
92 | process_rxframe (hdp, fbuf) | |
93 | register struct hdcb *hdp; | |
94 | register struct mbuf *fbuf; | |
95 | { | |
96 | register int queued = FALSE, frametype, pf; | |
97 | register struct Hdlc_frame *frame; | |
98 | ||
99 | frame = mtod (fbuf, struct Hdlc_frame *); | |
100 | pf = ((struct Hdlc_iframe *) frame) -> pf; | |
101 | ||
102 | hd_trace (hdp, RX, frame); | |
103 | if (frame -> address != ADDRESS_A && frame -> address != ADDRESS_B) | |
104 | return (queued); | |
105 | ||
106 | switch ((frametype = hd_decode (hdp, frame)) + hdp->hd_state) { | |
107 | case DM + DISC_SENT: | |
108 | case UA + DISC_SENT: | |
109 | /* | |
110 | * Link now closed. Leave timer running | |
111 | * so hd_timer() can periodically check the | |
112 | * status of interface driver flag bit IFF_UP. | |
113 | */ | |
114 | hdp->hd_state = DISCONNECTED; | |
115 | break; | |
116 | ||
117 | case DM + INIT: | |
118 | case UA + INIT: | |
119 | /* | |
120 | * This is a non-standard state change needed for DCEs | |
121 | * that do dynamic link selection. We can't go into the | |
122 | * usual "SEND DM" state because a DM is a SARM in LAP. | |
123 | */ | |
124 | hd_writeinternal (hdp, SABM, POLLOFF); | |
125 | hdp->hd_state = SABM_SENT; | |
126 | SET_TIMER (hdp); | |
127 | break; | |
128 | ||
129 | case SABM + DM_SENT: | |
130 | case SABM + WAIT_SABM: | |
131 | hd_writeinternal (hdp, UA, pf); | |
132 | case UA + SABM_SENT: | |
133 | case UA + WAIT_UA: | |
134 | KILL_TIMER (hdp); | |
135 | hd_initvars (hdp); | |
136 | hdp->hd_state = ABM; | |
137 | hd_message (hdp, "Link level operational"); | |
138 | /* Notify the packet level - to send RESTART. */ | |
315951e8 | 139 | (void) pk_ctlinput (PRC_LINKUP, hdp->hd_pkp); |
0f9bb9b6 KS |
140 | break; |
141 | ||
142 | case SABM + SABM_SENT: | |
143 | /* Got a SABM collision. Acknowledge the remote's SABM | |
144 | via UA but still wait for UA. */ | |
145 | hd_writeinternal (hdp, UA, pf); | |
146 | break; | |
147 | ||
148 | case SABM + ABM: | |
149 | /* Request to reset the link from the remote. */ | |
150 | KILL_TIMER (hdp); | |
151 | hd_message (hdp, "Link reset"); | |
152 | #ifdef HDLCDEBUG | |
153 | hd_dumptrace (hdp); | |
154 | #endif | |
155 | hd_flush (hdp->hd_ifp); | |
156 | hd_writeinternal (hdp, UA, pf); | |
157 | hd_initvars (hdp); | |
315951e8 | 158 | (void) pk_ctlinput (PRC_LINKRESET, hdp->hd_pkp); |
0f9bb9b6 KS |
159 | hdp->hd_resets++; |
160 | break; | |
161 | ||
162 | case SABM + WAIT_UA: | |
163 | hd_writeinternal (hdp, UA, pf); | |
164 | break; | |
165 | ||
166 | case DM + ABM: | |
167 | hd_message (hdp, "DM received: link down"); | |
168 | #ifdef HDLCDEBUG | |
169 | hd_dumptrace (hdp); | |
170 | #endif | |
315951e8 | 171 | (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp); |
0f9bb9b6 KS |
172 | hd_flush (hdp->hd_ifp); |
173 | case DM + DM_SENT: | |
174 | case DM + WAIT_SABM: | |
175 | case DM + WAIT_UA: | |
176 | hd_writeinternal (hdp, SABM, pf); | |
177 | hdp->hd_state = SABM_SENT; | |
178 | SET_TIMER (hdp); | |
179 | break; | |
180 | ||
181 | case DISC + INIT: | |
182 | case DISC + DM_SENT: | |
183 | case DISC + SABM_SENT: | |
184 | /* Note: This is a non-standard state change. */ | |
185 | hd_writeinternal (hdp, UA, pf); | |
186 | hd_writeinternal (hdp, SABM, POLLOFF); | |
187 | hdp->hd_state = SABM_SENT; | |
188 | SET_TIMER (hdp); | |
189 | break; | |
190 | ||
191 | case DISC + WAIT_UA: | |
192 | hd_writeinternal (hdp, DM, pf); | |
193 | SET_TIMER (hdp); | |
194 | hdp->hd_state = DM_SENT; | |
195 | break; | |
196 | ||
197 | case DISC + ABM: | |
198 | hd_message (hdp, "DISC received: link down"); | |
315951e8 | 199 | (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp); |
0f9bb9b6 KS |
200 | case DISC + WAIT_SABM: |
201 | hd_writeinternal (hdp, UA, pf); | |
202 | hdp->hd_state = DM_SENT; | |
203 | SET_TIMER (hdp); | |
204 | break; | |
205 | ||
206 | case UA + ABM: | |
207 | hd_message (hdp, "UA received: link down"); | |
315951e8 | 208 | (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp); |
0f9bb9b6 KS |
209 | case UA + WAIT_SABM: |
210 | hd_writeinternal (hdp, DM, pf); | |
211 | hdp->hd_state = DM_SENT; | |
212 | SET_TIMER (hdp); | |
213 | break; | |
214 | ||
215 | case FRMR + DM_SENT: | |
216 | hd_writeinternal (hdp, SABM, pf); | |
217 | hdp->hd_state = SABM_SENT; | |
218 | SET_TIMER (hdp); | |
219 | break; | |
220 | ||
221 | case FRMR + WAIT_SABM: | |
222 | hd_writeinternal (hdp, DM, pf); | |
223 | hdp->hd_state = DM_SENT; | |
224 | SET_TIMER (hdp); | |
225 | break; | |
226 | ||
227 | case FRMR + ABM: | |
228 | hd_message (hdp, "FRMR received: link down"); | |
315951e8 | 229 | (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp); |
0f9bb9b6 KS |
230 | #ifdef HDLCDEBUG |
231 | hd_dumptrace (hdp); | |
232 | #endif | |
233 | hd_flush (hdp->hd_ifp); | |
234 | hd_writeinternal (hdp, SABM, pf); | |
235 | hdp->hd_state = WAIT_UA; | |
236 | SET_TIMER (hdp); | |
237 | break; | |
238 | ||
239 | case RR + ABM: | |
240 | case RNR + ABM: | |
241 | case REJ + ABM: | |
242 | process_sframe (hdp, (struct Hdlc_sframe *)frame, frametype); | |
243 | break; | |
244 | ||
245 | case IFRAME + ABM: | |
246 | queued = process_iframe (hdp, fbuf, (struct Hdlc_iframe *)frame); | |
247 | break; | |
248 | ||
249 | case IFRAME + SABM_SENT: | |
250 | case RR + SABM_SENT: | |
251 | case RNR + SABM_SENT: | |
252 | case REJ + SABM_SENT: | |
253 | hd_writeinternal (hdp, DM, POLLON); | |
254 | hdp->hd_state = DM_SENT; | |
255 | SET_TIMER (hdp); | |
256 | break; | |
257 | ||
258 | case IFRAME + WAIT_SABM: | |
259 | case RR + WAIT_SABM: | |
260 | case RNR + WAIT_SABM: | |
261 | case REJ + WAIT_SABM: | |
262 | hd_writeinternal (hdp, FRMR, POLLOFF); | |
263 | SET_TIMER (hdp); | |
264 | break; | |
265 | ||
266 | case ILLEGAL + SABM_SENT: | |
267 | hdp->hd_unknown++; | |
268 | hd_writeinternal (hdp, DM, POLLOFF); | |
269 | hdp->hd_state = DM_SENT; | |
270 | SET_TIMER (hdp); | |
271 | break; | |
272 | ||
273 | case ILLEGAL + ABM: | |
274 | hd_message (hdp, "Unknown frame received: link down"); | |
315951e8 | 275 | (void) pk_ctlinput (PRC_LINKDOWN, hdp->hd_pkp); |
0f9bb9b6 KS |
276 | case ILLEGAL + WAIT_SABM: |
277 | hdp->hd_unknown++; | |
278 | #ifdef HDLCDEBUG | |
279 | hd_dumptrace (hdp); | |
280 | #endif | |
281 | hd_writeinternal (hdp, FRMR, POLLOFF); | |
282 | hdp->hd_state = WAIT_SABM; | |
283 | SET_TIMER (hdp); | |
284 | break; | |
285 | } | |
286 | ||
287 | return (queued); | |
288 | } | |
289 | ||
290 | process_iframe (hdp, fbuf, frame) | |
291 | register struct hdcb *hdp; | |
292 | struct mbuf *fbuf; | |
293 | register struct Hdlc_iframe *frame; | |
294 | { | |
295 | register int nr = frame -> nr, | |
296 | ns = frame -> ns, | |
297 | pf = frame -> pf; | |
298 | register int queued = FALSE; | |
299 | ||
300 | /* | |
301 | * Validate the iframe's N(R) value. It's N(R) value must be in | |
302 | * sync with our V(S) value and our "last received nr". | |
303 | */ | |
304 | ||
305 | if (valid_nr (hdp, nr, FALSE) == FALSE) { | |
306 | frame_reject (hdp, Z, frame); | |
307 | return (queued); | |
308 | } | |
309 | ||
310 | ||
311 | /* | |
312 | * This section tests the IFRAME for proper sequence. That is, it's | |
313 | * sequence number N(S) MUST be equal to V(S). | |
314 | */ | |
315 | ||
316 | if (ns != hdp->hd_vr) { | |
317 | hdp->hd_invalid_ns++; | |
318 | if (pf || (hdp->hd_condition & REJ_CONDITION) == 0) { | |
319 | hdp->hd_condition |= REJ_CONDITION; | |
320 | /* | |
321 | * Flush the transmit queue. This is ugly but we | |
322 | * have no choice. A reject response must be | |
323 | * immediately sent to the DCE. Failure to do so | |
324 | * may result in another out of sequence iframe | |
325 | * arriving (and thus sending another reject) | |
326 | * before the first reject is transmitted. This | |
327 | * will cause the DCE to receive two or more | |
328 | * rejects back to back, which must never happen. | |
329 | */ | |
330 | hd_flush (hdp->hd_ifp); | |
331 | hd_writeinternal (hdp, REJ, pf); | |
332 | } | |
333 | return (queued); | |
334 | } | |
335 | hdp->hd_condition &= ~REJ_CONDITION; | |
336 | ||
337 | /* | |
338 | * This section finally tests the IFRAME's sequence number against | |
339 | * the window size (K) and the sequence number of the last frame | |
340 | * we have acknowledged. If the IFRAME is completely correct then | |
341 | * it is queued for the packet level. | |
342 | */ | |
343 | ||
315951e8 KS |
344 | if (ns != (hdp -> hd_lasttxnr + hdp -> hd_xcp -> xc_lwsize) % MODULUS) { |
345 | hdp -> hd_vr = (hdp -> hd_vr + 1) % MODULUS; | |
0f9bb9b6 KS |
346 | if (pf == 1) { |
347 | /* Must generate a RR or RNR with final bit on. */ | |
348 | hd_writeinternal (hdp, RR, POLLON); | |
349 | } else | |
350 | /* | |
351 | * Hopefully we can piggyback the RR, if not we will generate | |
352 | * a RR when T3 timer expires. | |
353 | */ | |
354 | if (hdp -> hd_rrtimer == 0) | |
355 | hdp->hd_rrtimer = hd_t3; | |
356 | ||
357 | /* Forward iframe to packet level of X.25. */ | |
b84e7ca8 | 358 | fbuf -> m_data += HDHEADERLN; |
0f9bb9b6 | 359 | fbuf -> m_len -= HDHEADERLN; |
761493c1 | 360 | fbuf -> m_pkthdr.len -= HDHEADERLN; |
315951e8 | 361 | fbuf -> m_pkthdr.rcvif = (struct ifnet *)hdp -> hd_pkp; |
0f9bb9b6 KS |
362 | #ifdef BSD4_3 |
363 | fbuf->m_act = 0; /* probably not necessary */ | |
364 | #else | |
365 | { | |
366 | register struct mbuf *m; | |
367 | ||
368 | for (m = fbuf; m -> m_next; m = m -> m_next) | |
369 | m -> m_act = (struct mbuf *) 0; | |
370 | m -> m_act = (struct mbuf *) 1; | |
371 | } | |
372 | #endif | |
315951e8 | 373 | pk_input (fbuf); |
0f9bb9b6 KS |
374 | queued = TRUE; |
375 | hd_start (hdp); | |
376 | } else { | |
377 | /* | |
378 | * Here if the remote station has transmitted more iframes then | |
379 | * the number which have been acknowledged plus K. | |
380 | */ | |
381 | hdp->hd_invalid_ns++; | |
382 | frame_reject (hdp, W, frame); | |
383 | } | |
384 | return (queued); | |
385 | } | |
386 | ||
387 | /* | |
388 | * This routine is used to determine if a value (the middle parameter) | |
389 | * is between two other values. The low value is the first parameter | |
390 | * the high value is the last parameter. The routine checks the middle | |
391 | * value to see if it is within the range of the first and last values. | |
392 | * The reason we need this routine is the values are modulo some base | |
393 | * hence a simple test for greater or less than is not sufficient. | |
394 | */ | |
395 | ||
396 | bool | |
397 | range_check (rear, value, front) | |
398 | int rear, | |
399 | value, | |
400 | front; | |
401 | { | |
402 | register bool result = FALSE; | |
403 | ||
404 | if (front > rear) | |
405 | result = (rear <= value) && (value <= front); | |
406 | else | |
407 | result = (rear <= value) || (value <= front); | |
408 | ||
409 | return (result); | |
410 | } | |
411 | ||
412 | /* | |
413 | * This routine handles all the frame reject conditions which can | |
414 | * arise as a result of secondary processing. The frame reject | |
415 | * condition Y (frame length error) are handled elsewhere. | |
416 | */ | |
417 | ||
418 | static | |
419 | frame_reject (hdp, rejectcode, frame) | |
420 | struct hdcb *hdp; | |
421 | struct Hdlc_iframe *frame; | |
422 | { | |
423 | register struct Frmr_frame *frmr = &hd_frmr; | |
424 | ||
425 | frmr -> frmr_control = ((struct Hdlc_frame *) frame) -> control; | |
426 | ||
427 | frmr -> frmr_ns = frame -> ns; | |
428 | frmr -> frmr_f1_0 = 0; | |
429 | frmr -> frmr_nr = frame -> nr; | |
430 | frmr -> frmr_f2_0 = 0; | |
431 | ||
432 | frmr -> frmr_0000 = 0; | |
433 | frmr -> frmr_w = frmr -> frmr_x = frmr -> frmr_y = | |
434 | frmr -> frmr_z = 0; | |
435 | switch (rejectcode) { | |
436 | case Z: | |
437 | frmr -> frmr_z = 1;/* invalid N(R). */ | |
438 | break; | |
439 | ||
440 | case Y: | |
441 | frmr -> frmr_y = 1;/* iframe length error. */ | |
442 | break; | |
443 | ||
444 | case X: | |
445 | frmr -> frmr_x = 1;/* invalid information field. */ | |
446 | frmr -> frmr_w = 1; | |
447 | break; | |
448 | ||
449 | case W: | |
450 | frmr -> frmr_w = 1;/* invalid N(S). */ | |
451 | } | |
452 | ||
453 | hd_writeinternal (hdp, FRMR, POLLOFF); | |
454 | ||
455 | hdp->hd_state = WAIT_SABM; | |
456 | SET_TIMER (hdp); | |
457 | } | |
458 | ||
459 | /* | |
460 | * This procedure is invoked when ever we receive a supervisor | |
461 | * frame such as RR, RNR and REJ. All processing for these | |
462 | * frames is done here. | |
463 | */ | |
464 | ||
465 | process_sframe (hdp, frame, frametype) | |
466 | register struct hdcb *hdp; | |
467 | register struct Hdlc_sframe *frame; | |
468 | int frametype; | |
469 | { | |
470 | register int nr = frame -> nr, pf = frame -> pf, pollbit = 0; | |
471 | ||
472 | if (valid_nr (hdp, nr, pf) == TRUE) { | |
473 | switch (frametype) { | |
474 | case RR: | |
475 | hdp->hd_condition &= ~REMOTE_RNR_CONDITION; | |
476 | break; | |
477 | ||
478 | case RNR: | |
479 | hdp->hd_condition |= REMOTE_RNR_CONDITION; | |
480 | hdp->hd_retxcnt = 0; | |
481 | break; | |
482 | ||
483 | case REJ: | |
484 | hdp->hd_condition &= ~REMOTE_RNR_CONDITION; | |
485 | rej_routine (hdp, nr); | |
486 | } | |
487 | ||
488 | if (pf == 1) { | |
489 | hdp->hd_retxcnt = 0; | |
490 | hdp->hd_condition &= ~TIMER_RECOVERY_CONDITION; | |
491 | ||
42963956 KS |
492 | if (frametype == RR && hdp->hd_lastrxnr == hdp->hd_vs |
493 | && hdp->hd_timer == 0 && hdp->hd_txq.head == 0) | |
494 | hd_writeinternal(hdp, RR, pf); | |
495 | else | |
0f9bb9b6 KS |
496 | /* If any iframes have been queued because of the |
497 | timer condition, transmit then now. */ | |
498 | if (hdp->hd_condition & REMOTE_RNR_CONDITION) { | |
499 | /* Remote is busy or timer condition, so only | |
500 | send one. */ | |
501 | if (hdp->hd_vs != hdp->hd_retxqi) | |
502 | hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], pollbit); | |
503 | } | |
504 | else /* Flush the retransmit list first. */ | |
505 | while (hdp->hd_vs != hdp->hd_retxqi) | |
506 | hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], POLLOFF); | |
507 | } | |
508 | ||
509 | hd_start (hdp); | |
510 | } else | |
511 | frame_reject (hdp, Z, (struct Hdlc_iframe *)frame); /* Invalid N(R). */ | |
512 | } | |
513 | ||
514 | /* | |
515 | * This routine tests the validity of the N(R) which we have received. | |
516 | * If it is ok, then all the iframes which it acknowledges (if any) | |
517 | * will be freed. | |
518 | */ | |
519 | ||
520 | bool | |
521 | valid_nr (hdp, nr, finalbit) | |
522 | register struct hdcb *hdp; | |
523 | register int finalbit; | |
524 | { | |
525 | /* Make sure it really does acknowledge something. */ | |
526 | if (hdp->hd_lastrxnr == nr) | |
527 | return (TRUE); | |
528 | ||
529 | /* | |
530 | * This section validates the frame's N(R) value. It's N(R) value | |
531 | * must be in syncronization with our V(S) value and our "last | |
532 | * received nr" variable. If it is correct then we are able to send | |
533 | * more IFRAME's, else frame reject condition is entered. | |
534 | */ | |
535 | ||
536 | if (range_check (hdp->hd_lastrxnr, nr, hdp->hd_vs) == FALSE) { | |
537 | if ((hdp->hd_condition & TIMER_RECOVERY_CONDITION) && | |
538 | range_check (hdp->hd_vs, nr, hdp->hd_xx) == TRUE) | |
539 | hdp->hd_vs = nr; | |
540 | ||
541 | else { | |
542 | hdp->hd_invalid_nr++; | |
543 | return (FALSE); | |
544 | } | |
545 | } | |
546 | ||
547 | /* | |
548 | * If we get to here, we do have a valid frame but it might be out | |
549 | * of sequence. However, we should still accept the receive state | |
550 | * number N(R) since it has already passed our previous test and it | |
551 | * does acknowledge frames which we are sending. | |
552 | */ | |
553 | ||
554 | KILL_TIMER (hdp); | |
555 | free_iframes (hdp, &nr, finalbit);/* Free all acknowledged iframes */ | |
556 | if (nr != hdp->hd_vs) | |
557 | SET_TIMER (hdp); | |
558 | ||
559 | return (TRUE); | |
560 | } | |
561 | ||
562 | /* | |
563 | * This routine determines how many iframes need to be retransmitted. | |
564 | * It then resets the Send State Variable V(S) to accomplish this. | |
565 | */ | |
566 | ||
567 | static | |
568 | rej_routine (hdp, rejnr) | |
569 | register struct hdcb *hdp; | |
570 | register int rejnr; | |
571 | { | |
572 | register int anchor; | |
573 | ||
574 | /* | |
575 | * Flush the output queue. Any iframes queued for | |
576 | * transmission will be out of sequence. | |
577 | */ | |
578 | ||
579 | hd_flush (hdp->hd_ifp); | |
580 | ||
581 | /* | |
582 | * Determine how many frames should be re-transmitted. In the case | |
583 | * of a normal REJ this should be 1 to K. In the case of a timer | |
584 | * recovery REJ (ie. a REJ with the Final Bit on) this could be 0. | |
585 | */ | |
586 | ||
587 | anchor = hdp->hd_vs; | |
588 | if (hdp->hd_condition & TIMER_RECOVERY_CONDITION) | |
589 | anchor = hdp->hd_xx; | |
590 | ||
591 | anchor = (anchor - rejnr + 8) % MODULUS; | |
592 | ||
593 | if (anchor > 0) { | |
594 | ||
595 | /* There is at least one iframe to retransmit. */ | |
596 | KILL_TIMER (hdp); | |
597 | hdp->hd_vs = rejnr; | |
598 | ||
599 | while (hdp->hd_vs != hdp->hd_retxqi) | |
600 | hd_send_iframe (hdp, hdp->hd_retxq[hdp->hd_vs], POLLOFF); | |
601 | ||
602 | } | |
603 | hd_start (hdp); | |
604 | } | |
605 | ||
606 | /* | |
607 | * This routine frees iframes from the retransmit queue. It is called | |
608 | * when a previously written iframe is acknowledged. | |
609 | */ | |
610 | ||
611 | static | |
612 | free_iframes (hdp, nr, finalbit) | |
613 | register struct hdcb *hdp; | |
614 | int *nr; | |
615 | register int finalbit; | |
616 | ||
617 | { | |
618 | register int i, k; | |
619 | ||
620 | /* | |
621 | * We need to do the following because of a funny quirk in the | |
622 | * protocol. This case occures when in Timer recovery condition | |
623 | * we get a N(R) which acknowledges all the outstanding iframes | |
624 | * but with the Final Bit off. In this case we need to save the last | |
625 | * iframe for possible retransmission even though it has already been | |
626 | * acknowledged! | |
627 | */ | |
628 | ||
629 | if ((hdp->hd_condition & TIMER_RECOVERY_CONDITION) && *nr == hdp->hd_xx && finalbit == 0) { | |
630 | *nr = (*nr - 1 + 8) % MODULUS; | |
631 | /* printf ("QUIRK\n"); */ | |
632 | } | |
633 | ||
634 | k = (*nr - hdp->hd_lastrxnr + 8) % MODULUS; | |
635 | ||
636 | /* Loop here freeing all acknowledged iframes. */ | |
637 | for (i = 0; i < k; ++i) { | |
638 | m_freem (hdp->hd_retxq[hdp->hd_lastrxnr]); | |
639 | hdp->hd_retxq[hdp->hd_lastrxnr] = 0; | |
640 | hdp->hd_lastrxnr = (hdp->hd_lastrxnr + 1) % MODULUS; | |
641 | } | |
642 | ||
643 | } |