summaryrefslogtreecommitdiffstats
path: root/sys/net/if_sl.c
blob: b57eb93e8ba9f272ab12e15626c9646a6290ffb3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
/*
 * Copyright (c) 1987, 1989, 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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.
 *
 *	@(#)if_sl.c	8.6 (Berkeley) 2/1/94
 * $FreeBSD$
 */

/*
 * Serial Line interface
 *
 * Rick Adams
 * Center for Seismic Studies
 * 1300 N 17th Street, Suite 1450
 * Arlington, Virginia 22209
 * (703)276-7900
 * rick@seismo.ARPA
 * seismo!rick
 *
 * Pounded on heavily by Chris Torek (chris@mimsy.umd.edu, umcp-cs!chris).
 * N.B.: this belongs in netinet, not net, the way it stands now.
 * Should have a link-layer type designation, but wouldn't be
 * backwards-compatible.
 *
 * Converted to 4.3BSD Beta by Chris Torek.
 * Other changes made at Berkeley, based in part on code by Kirk Smith.
 * W. Jolitz added slip abort.
 *
 * Hacked almost beyond recognition by Van Jacobson (van@helios.ee.lbl.gov).
 * Added priority queuing for "interactive" traffic; hooks for TCP
 * header compression; ICMP filtering (at 2400 baud, some cretin
 * pinging you can use up all your bandwidth).  Made low clist behavior
 * more robust and slightly less likely to hang serial line.
 * Sped up a bunch of things.
 *
 * Note that splimp() is used throughout to block both (tty) input
 * interrupts and network activity; thus, splimp must be >= spltty.
 */

#include "opt_inet.h"
#include "opt_slip.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/proc.h>
#include <sys/dkstat.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/fcntl.h>
#include <sys/signalvar.h>
#include <sys/tty.h>
#include <sys/clist.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/module.h>
#include <sys/proc.h>

#include <net/if.h>
#include <net/if_types.h>
#include <net/netisr.h>

#if INET
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#else
#error "Huh? Slip without inet?"
#endif

#include <net/slcompress.h>
#include <net/if_slvar.h>
#include <net/slip.h>

#include <net/bpf.h>

static MALLOC_DEFINE(M_SL, "sl", "SLIP Interface");

/*
 * SLRMAX is a hard limit on input packet size.  To simplify the code
 * and improve performance, we require that packets fit in an mbuf
 * cluster, and if we get a compressed packet, there's enough extra
 * room to expand the header into a max length tcp/ip header (128
 * bytes).  So, SLRMAX can be at most
 *	MCLBYTES - 128
 *
 * SLMTU is the default transmit MTU. The transmit MTU should be kept
 * small enough so that interactive use doesn't suffer, but large
 * enough to provide good performance. 552 is a good choice for SLMTU
 * because it is high enough to not fragment TCP packets being routed
 * through this host. Packet fragmentation is bad with SLIP because
 * fragment headers aren't compressed. The previous assumptions about
 * the best MTU value don't really hold when using modern modems with
 * BTLZ data compression because the modem buffers play a much larger
 * role in interactive performance than the MTU. The MTU can be changed
 * at any time to suit the specific environment with ifconfig(8), and
 * its maximum value is defined as SLTMAX. SLTMAX must not be so large
 * that it would overflow the stack if BPF is configured (XXX; if_ppp.c
 * handles this better).
 *
 * SLIP_HIWAT is the amount of data that will be queued 'downstream'
 * of us (i.e., in clists waiting to be picked up by the tty output
 * interrupt).  If we queue a lot of data downstream, it's immune to
 * our t.o.s. queuing.
 * E.g., if SLIP_HIWAT is 1024, the interactive traffic in mixed
 * telnet/ftp will see a 1 sec wait, independent of the mtu (the
 * wait is dependent on the ftp window size but that's typically
 * 1k - 4k).  So, we want SLIP_HIWAT just big enough to amortize
 * the cost (in idle time on the wire) of the tty driver running
 * off the end of its clists & having to call back slstart for a
 * new packet.  For a tty interface with any buffering at all, this
 * cost will be zero.  Even with a totally brain dead interface (like
 * the one on a typical workstation), the cost will be <= 1 character
 * time.  So, setting SLIP_HIWAT to ~100 guarantees that we'll lose
 * at most 1% while maintaining good interactive response.
 */
#define	BUFOFFSET	(128+sizeof(struct ifnet **)+SLIP_HDRLEN)
#define	SLRMAX		(MCLBYTES - BUFOFFSET)
#define	SLBUFSIZE	(SLRMAX + BUFOFFSET)
#ifndef SLMTU
#define	SLMTU		552		/* default MTU */
#endif
#define	SLTMAX		1500		/* maximum MTU */
#define	SLIP_HIWAT	roundup(50,CBSIZE)
#define	CLISTRESERVE	1024		/* Can't let clists get too low */

/*
 * SLIP ABORT ESCAPE MECHANISM:
 *	(inspired by HAYES modem escape arrangement)
 *	1sec escape 1sec escape 1sec escape { 1sec escape 1sec escape }
 *	within window time signals a "soft" exit from slip mode by remote end
 *	if the IFF_DEBUG flag is on.
 */
#define	ABT_ESC		'\033'	/* can't be t_intr - distant host must know it*/
#define	ABT_IDLE	1	/* in seconds - idle before an escape */
#define	ABT_COUNT	3	/* count of escapes for abort */
#define	ABT_WINDOW	(ABT_COUNT*2+2)	/* in seconds - time to count */

static LIST_HEAD(sl_list, sl_softc) sl_list;

#define FRAME_END	 	0xc0		/* Frame End */
#define FRAME_ESCAPE		0xdb		/* Frame Esc */
#define TRANS_FRAME_END	 	0xdc		/* transposed frame end */
#define TRANS_FRAME_ESCAPE 	0xdd		/* transposed frame esc */

static int slisstatic(int);
static void slmarkstatic(int);
static struct sl_softc *slcreate(void);
static void sldestroy(struct sl_softc *sc);
static struct mbuf *sl_btom(struct sl_softc *, int);
static timeout_t sl_keepalive;
static timeout_t sl_outfill;
static l_close_t	slclose;
static l_rint_t		slinput;
static l_ioctl_t	sltioctl;
static int	slioctl(struct ifnet *, u_long, caddr_t);
static int	slopen(dev_t, struct tty *);
static int	sloutput(struct ifnet *,
	    struct mbuf *, struct sockaddr *, struct rtentry *);
static int	slstart(struct tty *);

static struct linesw slipdisc = {
	slopen,		slclose,	l_noread,	l_nowrite,
	sltioctl,	slinput,	slstart,	ttymodem,
	FRAME_END
};

/*
 * Called from boot code to establish sl interfaces.
 */
static int
sl_modevent(module_t mod, int type, void *data) 
{ 
	switch (type) { 
	case MOD_LOAD: 
		linesw[SLIPDISC] = slipdisc;
		LIST_INIT(&sl_list);
		break; 
	case MOD_UNLOAD: 
		printf("if_sl module unload - not possible for this module type\n"); 
		return EINVAL; 
	} 
	return 0; 
} 

static moduledata_t sl_mod = { 
	"if_sl", 
	sl_modevent, 
	0
}; 

DECLARE_MODULE(if_sl, sl_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);

static int *st_unit_list;
static size_t st_unit_max = 0;

static int
slisstatic(unit)
	int unit;
{
	size_t i;

	for (i = 0; i < st_unit_max; i++)
		if (st_unit_list[i] == unit)
			return 1;
	return 0;
}

static void
slmarkstatic(unit)
	int unit;
{
	int *t;

	if (slisstatic(unit))
		return;

	MALLOC(t, int *, sizeof(int) * (st_unit_max+1), M_SL, M_NOWAIT);
	if (t == NULL)
		return;

	if (st_unit_list) {
		bcopy(st_unit_list, t, sizeof(int) * st_unit_max);
		free(st_unit_list, M_SL);
	}
	st_unit_list = t;
	st_unit_list[st_unit_max] = unit;
	st_unit_max++;
}

static struct sl_softc *
slcreate()
{
	struct sl_softc *sc, *nc;
	int unit;
	struct mbuf *m;

	MALLOC(sc, struct sl_softc *, sizeof(*sc), M_SL, M_WAITOK | M_ZERO);

	m = m_gethdr(M_TRYWAIT, MT_DATA);
	if (m != NULL) {
		MCLGET(m, M_TRYWAIT);
		if ((m->m_flags & M_EXT) == 0) {
			m_free(m);
			m = NULL;
		}
	}

	if (m == NULL) {
		printf("sl: can't allocate buffer\n");
		free(sc, M_SL);
		return (NULL);
	}

	sc->sc_ep = mtod(m, u_char *) + SLBUFSIZE;
	sc->sc_mbuf = m;
	sc->sc_buf = sc->sc_ep - SLRMAX;
	sc->sc_mp = sc->sc_buf;
	sl_compress_init(&sc->sc_comp, -1);

	sc->sc_if.if_softc = sc;
	sc->sc_if.if_name = "sl";
	sc->sc_if.if_mtu = SLMTU;
	sc->sc_if.if_flags =
#ifdef SLIP_IFF_OPTS
	    SLIP_IFF_OPTS;
#else
	    IFF_POINTOPOINT | SC_AUTOCOMP | IFF_MULTICAST;
#endif
	sc->sc_if.if_type = IFT_SLIP;
	sc->sc_if.if_ioctl = slioctl;
	sc->sc_if.if_output = sloutput;
	sc->sc_if.if_snd.ifq_maxlen = 50;
	sc->sc_fastq.ifq_maxlen = 32;
	sc->sc_if.if_linkmib = sc;
	sc->sc_if.if_linkmiblen = sizeof *sc;
	mtx_init(&sc->sc_fastq.ifq_mtx, "sl_fastq", NULL, MTX_DEF);

	/*
	 * Find a suitable unit number.
	 */
	for (unit=0; ; unit++) {
		if (slisstatic(unit))
			continue;
		LIST_FOREACH(nc, &sl_list, sl_next) {
			if (nc->sc_if.if_unit == unit)
				continue;
		}
		break;
	}
	sc->sc_if.if_unit = unit;
	LIST_INSERT_HEAD(&sl_list, sc, sl_next);

	if_attach(&sc->sc_if);
	bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);

	return sc;
}


/*
 * Line specific open routine.
 * Attach the given tty to the first available sl unit.
 */
/* ARGSUSED */
static int
slopen(dev, tp)
	dev_t dev;
	register struct tty *tp;
{
	register struct sl_softc *sc;
	int s, error;

	error = suser(curthread);
	if (error)
		return (error);

	if (tp->t_line == SLIPDISC)
		return (0);

	if ((sc = slcreate()) == NULL)
		return (ENOBUFS);

	tp->t_sc = (caddr_t)sc;
	sc->sc_ttyp = tp;
	sc->sc_if.if_baudrate = tp->t_ospeed;
	ttyflush(tp, FREAD | FWRITE);
	tp->t_line = SLIPDISC;

	/*
	 * We don't use t_canq or t_rawq, so reduce their
	 * cblock resources to 0.  Reserve enough cblocks
	 * for t_outq to guarantee that we can fit a full
	 * packet if the SLIP_HIWAT check allows slstart()
	 * to loop.  Use the same value for the cblock
	 * limit since the reserved blocks should always
	 * be enough.  Reserving cblocks probably makes
	 * the CLISTRESERVE check unnecessary and wasteful.
	 */
	clist_alloc_cblocks(&tp->t_canq, 0, 0);
	clist_alloc_cblocks(&tp->t_outq,
	    SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
	    SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
	clist_alloc_cblocks(&tp->t_rawq, 0, 0);

	s = splnet();
	if_up(&sc->sc_if);
	splx(s);
	return (0);
}

static void
sldestroy(struct sl_softc *sc)
{
	bpfdetach(&sc->sc_if);
	if_detach(&sc->sc_if);
	LIST_REMOVE(sc, sl_next);
	m_free(sc->sc_mbuf);
	mtx_destroy(&sc->sc_fastq.ifq_mtx);
	if (sc->bpfbuf)
		free(sc->bpfbuf, M_SL);
	free(sc, M_SL);
}

/*
 * Line specific close routine.
 * Detach the tty from the sl unit.
 */
static int
slclose(tp,flag)
	struct tty *tp;
	int flag;
{
	register struct sl_softc *sc;
	int s;

	ttyflush(tp, FREAD | FWRITE);
	/*
	 * XXX the placement of the following spl is misleading.  tty
	 * interrupts must be blocked across line discipline switches
	 * and throughout closes to avoid races.
	 */
	s = splimp();		/* actually, max(spltty, splnet) */
	clist_free_cblocks(&tp->t_outq);
	tp->t_line = 0;
	sc = (struct sl_softc *)tp->t_sc;
	if (sc != NULL) {
		if (sc->sc_outfill) {
			sc->sc_outfill = 0;
			untimeout(sl_outfill, sc, sc->sc_ofhandle);
		}
		if (sc->sc_keepalive) {
			sc->sc_keepalive = 0;
			untimeout(sl_keepalive, sc, sc->sc_kahandle);
		}
		if_down(&sc->sc_if);
		sc->sc_ttyp = NULL;
		tp->t_sc = NULL;
		sldestroy(sc);
	}
	splx(s);
	return 0;
}

/*
 * Line specific (tty) ioctl routine.
 * Provide a way to get the sl unit number.
 */
/* ARGSUSED */
static int
sltioctl(tp, cmd, data, flag, td)
	struct tty *tp;
	u_long cmd;
	caddr_t data;
	int flag;
	struct thread *td;
{
	struct sl_softc *sc = (struct sl_softc *)tp->t_sc, *nc;
	int s, unit, wasup;

	s = splimp();
	switch (cmd) {
	case SLIOCGUNIT:
		*(int *)data = sc->sc_if.if_unit;
		break;

	case SLIOCSUNIT:
		unit = *(u_int *)data;
		if (unit < 0) {
			splx(s);
			return (ENXIO);
		}
		if (sc->sc_if.if_unit != unit) {
			LIST_FOREACH(nc, &sl_list, sl_next) {
				if (nc->sc_if.if_unit == *(u_int *)data) {
						splx(s);
						return (ENXIO);
				}
			}

			wasup = sc->sc_if.if_flags & IFF_UP;
			bpfdetach(&sc->sc_if);
			if_detach(&sc->sc_if);
			LIST_REMOVE(sc, sl_next);
			sc->sc_if.if_unit = unit;
			LIST_INSERT_HEAD(&sl_list, sc, sl_next);
			if_attach(&sc->sc_if);
			bpfattach(&sc->sc_if, DLT_SLIP, SLIP_HDRLEN);
			if (wasup)
				if_up(&sc->sc_if);
			else
				if_down(&sc->sc_if);
			clist_alloc_cblocks(&tp->t_outq,
			    SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1,
			    SLIP_HIWAT + 2 * sc->sc_if.if_mtu + 1);
		}
		slmarkstatic(unit);
		break;

	case SLIOCSKEEPAL:
		sc->sc_keepalive = *(u_int *)data * hz;
		if (sc->sc_keepalive) {
			sc->sc_flags |= SC_KEEPALIVE;
			sc->sc_kahandle = timeout(sl_keepalive, sc,
						  sc->sc_keepalive);
		} else {
			if ((sc->sc_flags & SC_KEEPALIVE) != 0) {
				untimeout(sl_keepalive, sc, sc->sc_kahandle);
				sc->sc_flags &= ~SC_KEEPALIVE;
			}
		}
		break;

	case SLIOCGKEEPAL:
		*(int *)data = sc->sc_keepalive / hz;
		break;

	case SLIOCSOUTFILL:
		sc->sc_outfill = *(u_int *)data * hz;
		if (sc->sc_outfill) {
			sc->sc_flags |= SC_OUTWAIT;
			sc->sc_ofhandle = timeout(sl_outfill, sc,
						  sc->sc_outfill);
		} else {
			if ((sc->sc_flags & SC_OUTWAIT) != 0) {
				untimeout(sl_outfill, sc, sc->sc_ofhandle);
				sc->sc_flags &= ~SC_OUTWAIT;
			}
		}
		break;

	case SLIOCGOUTFILL:
		*(int *)data = sc->sc_outfill / hz;
		break;

	default:
		splx(s);
		return (ENOIOCTL);
	}
	splx(s);
	return (0);
}

/*
 * Queue a packet.  Start transmission if not active.
 * Compression happens in slstart; if we do it here, IP TOS
 * will cause us to not compress "background" packets, because
 * ordering gets trashed.  It can be done for all packets in slstart.
 */
static int
sloutput(ifp, m, dst, rtp)
	struct ifnet *ifp;
	register struct mbuf *m;
	struct sockaddr *dst;
	struct rtentry *rtp;
{
	register struct sl_softc *sc = ifp->if_softc;
	register struct ip *ip;
	register struct ifqueue *ifq;
	int s;

	/*
	 * `Cannot happen' (see slioctl).  Someday we will extend
	 * the line protocol to support other address families.
	 */
	if (dst->sa_family != AF_INET) {
		if_printf(ifp, "af%d not supported\n", dst->sa_family);
		m_freem(m);
		sc->sc_if.if_noproto++;
		return (EAFNOSUPPORT);
	}

	if (sc->sc_ttyp == NULL || !(ifp->if_flags & IFF_UP)) {
		m_freem(m);
		return (ENETDOWN);
	}
	if ((sc->sc_ttyp->t_state & TS_CONNECTED) == 0) {
		m_freem(m);
		return (EHOSTUNREACH);
	}
	ifq = &sc->sc_if.if_snd;
	ip = mtod(m, struct ip *);
	if (sc->sc_if.if_flags & SC_NOICMP && ip->ip_p == IPPROTO_ICMP) {
		m_freem(m);
		return (ENETRESET);		/* XXX ? */
	}
	if (ip->ip_tos & IPTOS_LOWDELAY)
		ifq = &sc->sc_fastq;
	if (! IF_HANDOFF(ifq, m, NULL)) {
		sc->sc_if.if_oerrors++;
		return (ENOBUFS);
	}
	s = splimp();
	if (sc->sc_ttyp->t_outq.c_cc == 0)
		slstart(sc->sc_ttyp);
	splx(s);
	return (0);
}

/*
 * Start output on interface.  Get another datagram
 * to send from the interface queue and map it to
 * the interface before starting output.
 */
static int
slstart(tp)
	register struct tty *tp;
{
	register struct sl_softc *sc = (struct sl_softc *)tp->t_sc;
	register struct mbuf *m;
	register u_char *cp;
	register struct ip *ip;
	int s;
	register int len = 0;

	for (;;) {
		/*
		 * Call output process whether or not there is more in the
		 * output queue.  We are being called in lieu of ttstart
		 * and must do what it would.
		 */
		(*tp->t_oproc)(tp);

		if (tp->t_outq.c_cc != 0) {
			if (sc != NULL)
				sc->sc_flags &= ~SC_OUTWAIT;
			if (tp->t_outq.c_cc > SLIP_HIWAT)
				return 0;
		}

		/*
		 * This happens briefly when the line shuts down.
		 */
		if (sc == NULL)
			return 0;

		/*
		 * Get a packet and send it to the interface.
		 */
		s = splimp();
		IF_DEQUEUE(&sc->sc_fastq, m);
		if (m)
			sc->sc_if.if_omcasts++;		/* XXX */
		else
			IF_DEQUEUE(&sc->sc_if.if_snd, m);
		splx(s);
		if (m == NULL)
			return 0;

		/*
		 * We do the header compression here rather than in sloutput
		 * because the packets will be out of order if we are using TOS
		 * queueing, and the connection id compression will get
		 * munged when this happens.
		 */
		if (sc->sc_if.if_bpf) {
			/*
			 * We need to save the TCP/IP header before it's
			 * compressed.  To avoid complicated code, we just
			 * copy the entire packet into a stack buffer (since
			 * this is a serial line, packets should be short
			 * and/or the copy should be negligible cost compared
			 * to the packet transmission time).
			 */
			register struct mbuf *m1 = m;
			register u_char *cp;

			if (sc->bpfbuf == NULL)
				MALLOC(sc->bpfbuf, u_char *,
				    SLTMAX + SLIP_HDRLEN, M_SL, M_NOWAIT);

			if (sc->bpfbuf) {
				cp = sc->bpfbuf + SLIP_HDRLEN;
				len = 0;
				do {
					register int mlen = m1->m_len;

					bcopy(mtod(m1, caddr_t), cp, mlen);
					cp += mlen;
					len += mlen;
				} while ((m1 = m1->m_next) != NULL);
			}
		}
		ip = mtod(m, struct ip *);
		if (ip->ip_v == IPVERSION && ip->ip_p == IPPROTO_TCP) {
			if (sc->sc_if.if_flags & SC_COMPRESS)
				*mtod(m, u_char *) |= sl_compress_tcp(m, ip,
				    &sc->sc_comp, 1);
		}
		if (sc->sc_if.if_bpf && sc->bpfbuf) {
			/*
			 * Put the SLIP pseudo-"link header" in place.  The
			 * compressed header is now at the beginning of the
			 * mbuf.
			 */
			sc->bpfbuf[SLX_DIR] = SLIPDIR_OUT;
			bcopy(mtod(m, caddr_t), &sc->bpfbuf[SLX_CHDR], CHDR_LEN);
			BPF_TAP(&sc->sc_if, sc->bpfbuf, len + SLIP_HDRLEN);
		}

		/*
		 * If system is getting low on clists, just flush our
		 * output queue (if the stuff was important, it'll get
		 * retransmitted). Note that SLTMAX is used instead of
		 * the current if_mtu setting because connections that
		 * have already been established still use the original
		 * (possibly larger) mss.
		 */
		if (cfreecount < CLISTRESERVE + SLTMAX) {
			m_freem(m);
			sc->sc_if.if_collisions++;
			continue;
		}

		sc->sc_flags &= ~SC_OUTWAIT;
		/*
		 * The extra FRAME_END will start up a new packet, and thus
		 * will flush any accumulated garbage.  We do this whenever
		 * the line may have been idle for some time.
		 */
		if (tp->t_outq.c_cc == 0) {
			++sc->sc_if.if_obytes;
			(void) putc(FRAME_END, &tp->t_outq);
		}

		while (m) {
			register u_char *ep;

			cp = mtod(m, u_char *); ep = cp + m->m_len;
			while (cp < ep) {
				/*
				 * Find out how many bytes in the string we can
				 * handle without doing something special.
				 */
				register u_char *bp = cp;

				while (cp < ep) {
					switch (*cp++) {
					case FRAME_ESCAPE:
					case FRAME_END:
						--cp;
						goto out;
					}
				}
				out:
				if (cp > bp) {
					/*
					 * Put n characters at once
					 * into the tty output queue.
					 */
					if (b_to_q((char *)bp, cp - bp,
					    &tp->t_outq))
						break;
					sc->sc_if.if_obytes += cp - bp;
				}
				/*
				 * If there are characters left in the mbuf,
				 * the first one must be special..
				 * Put it out in a different form.
				 */
				if (cp < ep) {
					if (putc(FRAME_ESCAPE, &tp->t_outq))
						break;
					if (putc(*cp++ == FRAME_ESCAPE ?
					   TRANS_FRAME_ESCAPE : TRANS_FRAME_END,
					   &tp->t_outq)) {
						(void) unputc(&tp->t_outq);
						break;
					}
					sc->sc_if.if_obytes += 2;
				}
			}
			m = m_free(m);
		}

		if (putc(FRAME_END, &tp->t_outq)) {
			/*
			 * Not enough room.  Remove a char to make room
			 * and end the packet normally.
			 * If you get many collisions (more than one or two
			 * a day) you probably do not have enough clists
			 * and you should increase "nclist" in param.c.
			 */
			(void) unputc(&tp->t_outq);
			(void) putc(FRAME_END, &tp->t_outq);
			sc->sc_if.if_collisions++;
		} else {
			++sc->sc_if.if_obytes;
			sc->sc_if.if_opackets++;
		}
	}
	return 0;
}

/*
 * Copy data buffer to mbuf chain; add ifnet pointer.
 */
static struct mbuf *
sl_btom(sc, len)
	register struct sl_softc *sc;
	register int len;
{
	struct mbuf *m, *newm;

	MGETHDR(m, M_DONTWAIT, MT_DATA);
	if (m == NULL)
		return (NULL);

	/*
	 * If we have more than MHLEN bytes, it's cheaper to
	 * queue the cluster we just filled & allocate a new one
	 * for the input buffer.  Otherwise, fill the mbuf we
	 * allocated above.  Note that code in the input routine
	 * guarantees that packet will fit in a cluster.
	 */
	if (len >= MHLEN) {
		MCLGET(m, M_DONTWAIT);
		if ((m->m_flags & M_EXT) == 0) {
			/*
			 * we couldn't get a cluster - if memory's this
			 * low, it's time to start dropping packets.
			 */
			(void) m_free(m);
			return (NULL);
		}
		/* Swap the new and old clusters */
		newm = m;
		m = sc->sc_mbuf;
		sc->sc_mbuf = newm;
		sc->sc_ep = mtod(newm, u_char *) + SLBUFSIZE;
		
		m->m_data = (caddr_t)sc->sc_buf;
	} else
		bcopy((caddr_t)sc->sc_buf, mtod(m, caddr_t), len);

	m->m_len = len;
	m->m_pkthdr.len = len;
	m->m_pkthdr.rcvif = &sc->sc_if;
	return (m);
}

/*
 * tty interface receiver interrupt.
 */
static int
slinput(c, tp)
	register int c;
	register struct tty *tp;
{
	register struct sl_softc *sc;
	register struct mbuf *m;
	register int len;
	u_char chdr[CHDR_LEN];

	tk_nin++;
	sc = (struct sl_softc *)tp->t_sc;
	if (sc == NULL)
		return 0;
	if (c & TTY_ERRORMASK || (tp->t_state & TS_CONNECTED) == 0) {
		sc->sc_flags |= SC_ERROR;
		return 0;
	}
	c &= TTY_CHARMASK;

	++sc->sc_if.if_ibytes;

	if (sc->sc_if.if_flags & IFF_DEBUG) {
		if (c == ABT_ESC) {
			/*
			 * If we have a previous abort, see whether
			 * this one is within the time limit.
			 */
			if (sc->sc_abortcount &&
			    time_second >= sc->sc_starttime + ABT_WINDOW)
				sc->sc_abortcount = 0;
			/*
			 * If we see an abort after "idle" time, count it;
			 * record when the first abort escape arrived.
			 */
			if (time_second >= sc->sc_lasttime + ABT_IDLE) {
				if (++sc->sc_abortcount == 1)
					sc->sc_starttime = time_second;
				if (sc->sc_abortcount >= ABT_COUNT) {
					slclose(tp,0);
					return 0;
				}
			}
		} else
			sc->sc_abortcount = 0;
		sc->sc_lasttime = time_second;
	}

	switch (c) {

	case TRANS_FRAME_ESCAPE:
		if (sc->sc_escape)
			c = FRAME_ESCAPE;
		break;

	case TRANS_FRAME_END:
		if (sc->sc_escape)
			c = FRAME_END;
		break;

	case FRAME_ESCAPE:
		sc->sc_escape = 1;
		return 0;

	case FRAME_END:
		sc->sc_flags &= ~SC_KEEPALIVE;
		if(sc->sc_flags & SC_ERROR) {
			sc->sc_flags &= ~SC_ERROR;
			goto newpack;
		}
		len = sc->sc_mp - sc->sc_buf;
		if (len < 3)
			/* less than min length packet - ignore */
			goto newpack;

		if (sc->sc_if.if_bpf) {
			/*
			 * Save the compressed header, so we
			 * can tack it on later.  Note that we
			 * will end up copying garbage in some
			 * cases but this is okay.  We remember
			 * where the buffer started so we can
			 * compute the new header length.
			 */
			bcopy(sc->sc_buf, chdr, CHDR_LEN);
		}

		if ((c = (*sc->sc_buf & 0xf0)) != (IPVERSION << 4)) {
			if (c & 0x80)
				c = TYPE_COMPRESSED_TCP;
			else if (c == TYPE_UNCOMPRESSED_TCP)
				*sc->sc_buf &= 0x4f; /* XXX */
			/*
			 * We've got something that's not an IP packet.
			 * If compression is enabled, try to decompress it.
			 * Otherwise, if `auto-enable' compression is on and
			 * it's a reasonable packet, decompress it and then
			 * enable compression.  Otherwise, drop it.
			 */
			if (sc->sc_if.if_flags & SC_COMPRESS) {
				len = sl_uncompress_tcp(&sc->sc_buf, len,
							(u_int)c, &sc->sc_comp);
				if (len <= 0)
					goto error;
			} else if ((sc->sc_if.if_flags & SC_AUTOCOMP) &&
			    c == TYPE_UNCOMPRESSED_TCP && len >= 40) {
				len = sl_uncompress_tcp(&sc->sc_buf, len,
							(u_int)c, &sc->sc_comp);
				if (len <= 0)
					goto error;
				sc->sc_if.if_flags |= SC_COMPRESS;
			} else
				goto error;
		}
		if (sc->sc_if.if_bpf) {
			/*
			 * Put the SLIP pseudo-"link header" in place.
			 * We couldn't do this any earlier since
			 * decompression probably moved the buffer
			 * pointer.  Then, invoke BPF.
			 */
			register u_char *hp = sc->sc_buf - SLIP_HDRLEN;

			hp[SLX_DIR] = SLIPDIR_IN;
			bcopy(chdr, &hp[SLX_CHDR], CHDR_LEN);
			BPF_TAP(&sc->sc_if, hp, len + SLIP_HDRLEN);
		}
		m = sl_btom(sc, len);
		if (m == NULL)
			goto error;

		sc->sc_if.if_ipackets++;

		if ((sc->sc_if.if_flags & IFF_UP) == 0) {
			m_freem(m);
			goto newpack;
		}

		if (! IF_HANDOFF(&ipintrq, m, NULL)) {
			sc->sc_if.if_ierrors++;
			sc->sc_if.if_iqdrops++;
		} else {
			schednetisr(NETISR_IP);
		}
		goto newpack;
	}
	if (sc->sc_mp < sc->sc_ep) {
		*sc->sc_mp++ = c;
		sc->sc_escape = 0;
		return 0;
	}

	/* can't put lower; would miss an extra frame */
	sc->sc_flags |= SC_ERROR;

error:
	sc->sc_if.if_ierrors++;
newpack:
	sc->sc_mp = sc->sc_buf = sc->sc_ep - SLRMAX;
	sc->sc_escape = 0;
	return 0;
}

/*
 * Process an ioctl request.
 */
static int
slioctl(ifp, cmd, data)
	register struct ifnet *ifp;
	u_long cmd;
	caddr_t data;
{
	register struct ifaddr *ifa = (struct ifaddr *)data;
	register struct ifreq *ifr = (struct ifreq *)data;
	register int s, error = 0;
	struct sl_softc *sc = ifp->if_softc;

	s = splimp();

	switch (cmd) {

	case SIOCSIFFLAGS:
		/*
		 * if.c will set the interface up even if we
		 * don't want it to.
		 */
		if (sc->sc_ttyp == NULL) {
			ifp->if_flags &= ~IFF_UP;
		}
		break;
	case SIOCSIFADDR:
		/*
		 * This is "historical" - set the interface up when
		 * setting the address.
		 */
		if (ifa->ifa_addr->sa_family == AF_INET) {
			if (sc->sc_ttyp != NULL)
				ifp->if_flags |= IFF_UP;
		} else {
			error = EAFNOSUPPORT;
		}
		break;

	case SIOCSIFDSTADDR:
		if (ifa->ifa_addr->sa_family != AF_INET)
			error = EAFNOSUPPORT;
		break;

	case SIOCADDMULTI:
	case SIOCDELMULTI:
		break;

	case SIOCSIFMTU:
		/*
		 * Set the interface MTU.
		 */
		if (ifr->ifr_mtu > SLTMAX)
			error = EINVAL;
		else {
			struct tty *tp;

			ifp->if_mtu = ifr->ifr_mtu;
			tp = sc->sc_ttyp;
			if (tp != NULL)
				clist_alloc_cblocks(&tp->t_outq,
				    SLIP_HIWAT + 2 * ifp->if_mtu + 1,
				    SLIP_HIWAT + 2 * ifp->if_mtu + 1);
		}
		break;

	default:
		error = EINVAL;
	}
	splx(s);
	return (error);
}

static void
sl_keepalive(chan)
	void *chan;
{
	struct sl_softc *sc = chan;

	if (sc->sc_keepalive) {
		if (sc->sc_flags & SC_KEEPALIVE) {
			if (sc->sc_ttyp->t_pgrp != NULL) {
				PGRP_LOCK(sc->sc_ttyp->t_pgrp);
				pgsignal (sc->sc_ttyp->t_pgrp, SIGURG, 1);
				PGRP_UNLOCK(sc->sc_ttyp->t_pgrp);
			}
		} else
			sc->sc_flags |= SC_KEEPALIVE;
		sc->sc_kahandle = timeout(sl_keepalive, sc, sc->sc_keepalive);
	} else {
		sc->sc_flags &= ~SC_KEEPALIVE;
	}
}

static void
sl_outfill(chan)
	void *chan;
{
	struct sl_softc *sc = chan;
	register struct tty *tp = sc->sc_ttyp;
	int s;

	if (sc->sc_outfill && tp != NULL) {
		if (sc->sc_flags & SC_OUTWAIT) {
			s = splimp ();
			++sc->sc_if.if_obytes;
			(void) putc(FRAME_END, &tp->t_outq);
			(*tp->t_oproc)(tp);
			splx (s);
		} else
			sc->sc_flags |= SC_OUTWAIT;
		sc->sc_ofhandle = timeout(sl_outfill, sc, sc->sc_outfill);
	} else {
		sc->sc_flags &= ~SC_OUTWAIT;
	}
}
OpenPOWER on IntegriCloud