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
|
/*
* Copyright (c) 1998-2000 Luigi Rizzo
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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.
*
* $FreeBSD$
*/
/*
* This code implements bridging in FreeBSD. It only acts on ethernet
* type of interfaces (others are still usable for routing).
* A bridging table holds the source MAC address/dest. interface for each
* known node. The table is indexed using an hash of the source address.
*
* Input packets are tapped near the beginning of ether_input(), and
* analysed by calling bridge_in(). Depending on the result, the packet
* can be forwarded to one or more output interfaces using bdg_forward(),
* and/or sent to the upper layer (e.g. in case of multicast).
*
* Output packets are intercepted near the end of ether_output(),
* the correct destination is selected calling bdg_dst_lookup(),
* and then forwarding is done using bdg_forward().
* Bridging is controlled by the sysctl variable net.link.ether.bridge
*
* The arp code is also modified to let a machine answer to requests
* irrespective of the port the request came from.
*
* In case of loops in the bridging topology, the bridge detects this
* event and temporarily mutes output bridging on one of the ports.
* Periodically, interfaces are unmuted by bdg_timeout().
* Muting is only implemented as a safety measure, and also as
* a mechanism to support a user-space implementation of the spanning
* tree algorithm. In the final release, unmuting will only occur
* because of explicit action of the user-level daemon.
*
* To build a bridging kernel, use the following option
* option BRIDGE
* and then at runtime set the sysctl variable to enable bridging.
*
* Only one interface is supposed to have addresses set (but
* there are no problems in practice if you set addresses for more
* than one interface).
* Bridging will act before routing, but nothing prevents a machine
* from doing both (modulo bugs in the implementation...).
*
* THINGS TO REMEMBER
* - bridging requires some (small) modifications to the interface
* driver. Not all of them have been changed, see the "ed" and "de"
* drivers as examples on how to operate.
* - bridging is incompatible with multicast routing on the same
* machine. There is not an easy fix to this.
* - loop detection is still not very robust.
* - the interface of bdg_forward() could be improved.
*/
#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/systm.h>
#include <sys/socket.h> /* for net/if.h */
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_types.h>
#include <netinet/in.h> /* for struct arpcom */
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/if_ether.h> /* for struct arpcom */
#include "opt_ipfw.h"
#include "opt_ipdn.h"
#if defined(IPFIREWALL)
#include <net/route.h>
#include <netinet/ip_fw.h>
#if defined(DUMMYNET)
#include <netinet/ip_dummynet.h>
#endif
#endif
#include <net/bridge.h>
/*
* For debugging, you can use the following macros.
* remember, rdtsc() only works on Pentium-class machines
quad_t ticks;
DDB(ticks = rdtsc();)
... interesting code ...
DDB(bdg_fw_ticks += (u_long)(rdtsc() - ticks) ; bdg_fw_count++ ;)
*
*/
#define DDB(x) x
#define DEB(x)
static void bdginit(void *);
static void flush_table(void);
static void bdg_promisc_on(void);
static void parse_bdg_cfg(void);
static int bdg_ipfw = 0 ;
int do_bridge = 0;
bdg_hash_table *bdg_table = NULL ;
/*
* System initialization
*/
SYSINIT(interfaces, SI_SUB_PROTO_IF, SI_ORDER_FIRST, bdginit, NULL)
/*
* We need additional info for the bridge. The bdg_ifp2sc[] array
* provides a pointer to this struct using the if_index.
* bdg_softc has a backpointer to the struct ifnet, the bridge
* flags, and a cluster (bridging occurs only between port of the
* same cluster).
*/
struct bdg_softc {
struct ifnet *ifp ;
/* ((struct arpcom *)ifp)->ac_enaddr is the eth. addr */
int flags ;
#define IFF_BDG_PROMISC 0x0001 /* set promisc mode on this if. */
#define IFF_MUTE 0x0002 /* mute this if for bridging. */
#define IFF_USED 0x0004 /* use this if for bridging. */
short cluster_id ; /* in network format */
u_long magic;
} ;
static struct bdg_stats bdg_stats ;
static struct bdg_softc *ifp2sc = NULL ;
/* XXX make it static of size BDG_MAX_PORTS */
#define USED(ifp) (ifp2sc[ifp->if_index].flags & IFF_USED)
#define MUTED(ifp) (ifp2sc[ifp->if_index].flags & IFF_MUTE)
#define MUTE(ifp) ifp2sc[ifp->if_index].flags |= IFF_MUTE
#define UNMUTE(ifp) ifp2sc[ifp->if_index].flags &= ~IFF_MUTE
#define CLUSTER(ifp) (ifp2sc[ifp->if_index].cluster_id)
#define IFP_CHK(ifp, x) \
if (ifp2sc[ifp->if_index].magic != 0xDEADBEEF) { x ; }
#define SAMECLUSTER(ifp,src) \
(src == NULL || CLUSTER(ifp) == CLUSTER(src) )
/*
* turn off promisc mode, optionally clear the IFF_USED flag
*/
static void
bdg_promisc_off(int clear_used)
{
struct ifnet *ifp ;
for (ifp = ifnet.tqh_first; ifp; ifp = ifp->if_link.tqe_next ) {
if ( (ifp2sc[ifp->if_index].flags & IFF_BDG_PROMISC) ) {
int s, ret ;
s = splimp();
ret = ifpromisc(ifp, 0);
splx(s);
ifp2sc[ifp->if_index].flags &= ~(IFF_BDG_PROMISC|IFF_MUTE) ;
if (clear_used)
ifp2sc[ifp->if_index].flags &= ~(IFF_USED) ;
printf(">> now %s%d promisc ON if_flags 0x%x bdg_flags 0x%x\n",
ifp->if_name, ifp->if_unit,
ifp->if_flags, ifp2sc[ifp->if_index].flags);
}
}
}
/*
* set promisc mode on the interfaces we use.
*/
static void
bdg_promisc_on()
{
struct ifnet *ifp ;
int s ;
for (ifp = ifnet.tqh_first; ifp; ifp = ifp->if_link.tqe_next ) {
if ( !USED(ifp) )
continue ;
if ( 0 == ( ifp->if_flags & IFF_UP) ) {
s = splimp();
if_up(ifp);
splx(s);
}
if ( !(ifp2sc[ifp->if_index].flags & IFF_BDG_PROMISC) ) {
int ret ;
s = splimp();
ret = ifpromisc(ifp, 1);
splx(s);
ifp2sc[ifp->if_index].flags |= IFF_BDG_PROMISC ;
printf(">> now %s%d promisc ON if_flags 0x%x bdg_flags 0x%x\n",
ifp->if_name, ifp->if_unit,
ifp->if_flags, ifp2sc[ifp->if_index].flags);
}
if (MUTED(ifp)) {
printf(">> unmuting %s%d\n", ifp->if_name, ifp->if_unit);
UNMUTE(ifp) ;
}
}
}
static int
sysctl_bdg (SYSCTL_HANDLER_ARGS)
{
int error, oldval = do_bridge ;
error = sysctl_handle_int(oidp,
oidp->oid_arg1, oidp->oid_arg2, req);
DEB( printf("called sysctl for bridge name %s arg2 %d val %d->%d\n",
oidp->oid_name, oidp->oid_arg2,
oldval, do_bridge); )
if (bdg_table == NULL)
do_bridge = 0 ;
if (oldval != do_bridge) {
flush_table();
if (do_bridge == 0)
bdg_promisc_off( 0 ); /* leave IFF_USED set */
else
bdg_promisc_on();
}
return error ;
}
static char bridge_cfg[256] = { "" } ;
/*
* parse the config string, set IFF_USED, name and cluster_id
* for all interfaces found.
*/
static void
parse_bdg_cfg()
{
char *p, *beg ;
int i, l, cluster;
struct bdg_softc *b;
for (p= bridge_cfg; *p ; p++) {
/* interface names begin with [a-z] and continue up to ':' */
if (*p < 'a' || *p > 'z')
continue ;
for ( beg = p ; *p && *p != ':' ; p++ )
;
if (*p == 0) /* end of string, ':' not found */
return ;
l = p - beg ; /* length of name string */
p++ ;
DDB(printf("-- match beg(%d) <%s> p <%s>\n", l, beg, p);)
for (cluster = 0 ; *p && *p >= '0' && *p <= '9' ; p++)
cluster = cluster*10 + (*p -'0');
/*
* now search in bridge strings
*/
for (i=0, b = ifp2sc ; i < if_index ; i++, b++) {
char buf[32];
struct ifnet *ifp = b->ifp ;
if (ifp == NULL)
continue;
sprintf(buf, "%s%d", ifp->if_name, ifp->if_unit);
if (!strncmp(beg, buf, l)) { /* XXX not correct for >10 if! */
b->cluster_id = htons(cluster) ;
b->flags |= IFF_USED ;
sprintf(bdg_stats.s[ifp->if_index].name+l,
":%d", cluster);
DDB(printf("--++ found %s\n",
bdg_stats.s[ifp->if_index].name);)
break ;
}
}
}
}
static int
sysctl_bdg_cfg (SYSCTL_HANDLER_ARGS)
{
int error = 0 ;
char oldval[256] ;
strcpy(oldval, bridge_cfg) ;
error = sysctl_handle_string(oidp,
bridge_cfg, oidp->oid_arg2, req);
DEB(
printf("called sysctl for bridge name %s arg2 %d err %d val %s->%s\n",
oidp->oid_name, oidp->oid_arg2,
error,
oldval, bridge_cfg);
)
if (strcmp(oldval, bridge_cfg)) {
bdg_promisc_off( 1 ); /* reset previously-used interfaces */
flush_table();
parse_bdg_cfg(); /* and set new ones... */
if (do_bridge)
bdg_promisc_on(); /* re-enable interfaces */
}
return error ;
}
SYSCTL_DECL(_net_link_ether);
SYSCTL_PROC(_net_link_ether, OID_AUTO, bridge_cfg, CTLTYPE_STRING|CTLFLAG_RW,
&bridge_cfg, sizeof(bridge_cfg), &sysctl_bdg_cfg, "A",
"Bridge configuration");
SYSCTL_PROC(_net_link_ether, OID_AUTO, bridge, CTLTYPE_INT|CTLFLAG_RW,
&do_bridge, 0, &sysctl_bdg, "I", "Bridging");
SYSCTL_INT(_net_link_ether, OID_AUTO, bridge_ipfw, CTLFLAG_RW,
&bdg_ipfw,0,"Pass bridged pkts through firewall");
int bdg_ipfw_drops;
SYSCTL_INT(_net_link_ether, OID_AUTO, bridge_ipfw_drop,
CTLFLAG_RW, &bdg_ipfw_drops,0,"");
int bdg_ipfw_colls;
SYSCTL_INT(_net_link_ether, OID_AUTO, bridge_ipfw_collisions,
CTLFLAG_RW, &bdg_ipfw_colls,0,"");
#if 1 /* diagnostic vars */
int bdg_in_count = 0 , bdg_in_ticks = 0 , bdg_fw_count = 0, bdg_fw_ticks = 0 ;
SYSCTL_INT(_net_link_ether, OID_AUTO, bdginc, CTLFLAG_RW, &bdg_in_count,0,"");
SYSCTL_INT(_net_link_ether, OID_AUTO, bdgint, CTLFLAG_RW, &bdg_in_ticks,0,"");
SYSCTL_INT(_net_link_ether, OID_AUTO, bdgfwc, CTLFLAG_RW, &bdg_fw_count,0,"");
SYSCTL_INT(_net_link_ether, OID_AUTO, bdgfwt, CTLFLAG_RW, &bdg_fw_ticks,0,"");
#endif
SYSCTL_STRUCT(_net_link_ether, PF_BDG, bdgstats,
CTLFLAG_RD, &bdg_stats , bdg_stats, "bridge statistics");
static int bdg_loops ;
/*
* completely flush the bridge table.
*/
static void
flush_table()
{
int s,i;
if (bdg_table == NULL)
return ;
s = splimp();
for (i=0; i< HASH_SIZE; i++)
bdg_table[i].name= NULL; /* clear table */
splx(s);
}
/*
* called periodically to flush entries etc.
*/
static void
bdg_timeout(void *dummy)
{
static int slowtimer = 0 ;
if (do_bridge) {
static int age_index = 0 ; /* index of table position to age */
int l = age_index + HASH_SIZE/4 ;
/*
* age entries in the forwarding table.
*/
if (l > HASH_SIZE)
l = HASH_SIZE ;
for (; age_index < l ; age_index++)
if (bdg_table[age_index].used)
bdg_table[age_index].used = 0 ;
else if (bdg_table[age_index].name) {
/* printf("xx flushing stale entry %d\n", age_index); */
bdg_table[age_index].name = NULL ;
}
if (age_index >= HASH_SIZE)
age_index = 0 ;
if (--slowtimer <= 0 ) {
slowtimer = 5 ;
bdg_promisc_on() ; /* we just need unmute, really */
bdg_loops = 0 ;
}
}
timeout(bdg_timeout, (void *)0, 2*hz );
}
/*
* local MAC addresses are held in a small array. This makes comparisons
* much faster.
*/
unsigned char bdg_addresses[6*BDG_MAX_PORTS];
int bdg_ports ;
/*
* initialization of bridge code. This needs to be done after all
* interfaces have been configured.
*/
static void
bdginit(void *dummy)
{
int i ;
struct ifnet *ifp;
struct arpcom *ac ;
u_char *eth_addr ;
struct bdg_softc *bp;
if (bdg_table == NULL)
bdg_table = (struct hash_table *)
malloc(HASH_SIZE * sizeof(struct hash_table),
M_IFADDR, M_WAITOK);
flush_table();
ifp2sc = malloc(BDG_MAX_PORTS * sizeof(struct bdg_softc),
M_IFADDR, M_WAITOK );
bzero(ifp2sc, BDG_MAX_PORTS * sizeof(struct bdg_softc) );
bzero(&bdg_stats, sizeof(bdg_stats) );
bdg_ports = 0 ;
eth_addr = bdg_addresses ;
printf("BRIDGE 990810, have %d interfaces\n", if_index);
for (i = 0 , ifp = ifnet.tqh_first ; i < if_index ;
i++, ifp = ifp->if_link.tqe_next)
if (ifp->if_type == IFT_ETHER) { /* ethernet ? */
bp = &ifp2sc[ifp->if_index] ;
ac = (struct arpcom *)ifp;
sprintf(bridge_cfg + strlen(bridge_cfg),
"%s%d:1,", ifp->if_name, ifp->if_unit);
printf("-- index %d %s type %d phy %d addrl %d addr %6D\n",
ifp->if_index,
bdg_stats.s[ifp->if_index].name,
(int)ifp->if_type, (int) ifp->if_physical,
(int)ifp->if_addrlen,
ac->ac_enaddr, "." );
bcopy(ac->ac_enaddr, eth_addr, 6);
eth_addr += 6 ;
bp->ifp = ifp ;
bp->flags = IFF_USED ;
bp->cluster_id = htons(1) ;
bp->magic = 0xDEADBEEF ;
sprintf(bdg_stats.s[ifp->if_index].name,
"%s%d:%d", ifp->if_name, ifp->if_unit,
ntohs(bp->cluster_id));
bdg_ports ++ ;
}
bdg_timeout(0);
do_bridge=0;
}
/*
* bridge_in() is invoked to perform bridging decision on input packets.
*
* On Input:
* eh Ethernet header of the incoming packet.
*
* On Return: destination of packet, one of
* BDG_BCAST broadcast
* BDG_MCAST multicast
* BDG_LOCAL is only for a local address (do not forward)
* BDG_DROP drop the packet
* ifp ifp of the destination interface.
*
* Forwarding is not done directly to give a chance to some drivers
* to fetch more of the packet, or simply drop it completely.
*/
struct ifnet *
bridge_in(struct ifnet *ifp, struct ether_header *eh)
{
int index;
struct ifnet *dst , *old ;
int dropit = MUTED(ifp) ;
/*
* hash the source address
*/
index= HASH_FN(eh->ether_shost);
bdg_table[index].used = 1 ;
old = bdg_table[index].name ;
if ( old ) { /* the entry is valid. */
IFP_CHK(old, printf("bridge_in-- reading table\n") );
if (!BDG_MATCH( eh->ether_shost, bdg_table[index].etheraddr) ) {
bdg_ipfw_colls++ ;
bdg_table[index].name = NULL ;
} else if (old != ifp) {
/*
* found a loop. Either a machine has moved, or there
* is a misconfiguration/reconfiguration of the network.
* First, do not forward this packet!
* Record the relocation anyways; then, if loops persist,
* suspect a reconfiguration and disable forwarding
* from the old interface.
*/
bdg_table[index].name = ifp ; /* relocate address */
printf("-- loop (%d) %6D to %s%d from %s%d (%s)\n",
bdg_loops, eh->ether_shost, ".",
ifp->if_name, ifp->if_unit,
old->if_name, old->if_unit,
MUTED(old) ? "muted":"active");
dropit = 1 ;
if ( !MUTED(old) ) {
if (++bdg_loops > 10)
MUTE(old) ;
}
}
}
/*
* now write the source address into the table
*/
if (bdg_table[index].name == NULL) {
DEB(printf("new addr %6D at %d for %s%d\n",
eh->ether_shost, ".", index, ifp->if_name, ifp->if_unit);)
bcopy(eh->ether_shost, bdg_table[index].etheraddr, 6);
bdg_table[index].name = ifp ;
}
dst = bridge_dst_lookup(eh);
/* Return values:
* BDG_BCAST, BDG_MCAST, BDG_LOCAL, BDG_UNKNOWN, BDG_DROP, ifp.
* For muted interfaces, the first 3 are changed in BDG_LOCAL,
* and others to BDG_DROP. Also, for incoming packets, ifp is changed
* to BDG_DROP in case ifp == src . These mods are not necessary
* for outgoing packets from ether_output().
*/
BDG_STAT(ifp, BDG_IN);
switch ((int)dst) {
case (int)BDG_BCAST:
case (int)BDG_MCAST:
case (int)BDG_LOCAL:
case (int)BDG_UNKNOWN:
case (int)BDG_DROP:
BDG_STAT(ifp, dst);
break ;
default :
if (dst == ifp || dropit )
BDG_STAT(ifp, BDG_DROP);
else
BDG_STAT(ifp, BDG_FORWARD);
break ;
}
if ( dropit ) {
if (dst == BDG_BCAST || dst == BDG_MCAST || dst == BDG_LOCAL)
return BDG_LOCAL ;
else
return BDG_DROP ;
} else {
return (dst == ifp ? BDG_DROP : dst ) ;
}
}
/*
* Forward to dst, excluding src port and muted interfaces.
* The packet is freed if possible (i.e. surely not of interest for
* the upper layer), otherwise a copy is left for use by the caller
* (pointer in *m0).
*
* It would be more efficient to make bdg_forward() always consume
* the packet, leaving to the caller the task to check if it needs a copy
* and get one in case. As it is now, bdg_forward() can sometimes make
* a copy whereas it is not necessary.
*
* INPUT:
* *m0 -- ptr to pkt (not null at call time)
* *dst -- destination (special value or ifnet *)
* (*m0)->m_pkthdr.rcvif -- NULL only for output pkts.
* OUTPUT:
* *m0 -- pointer to the packet (NULL if still existent)
*/
int
bdg_forward(struct mbuf **m0, struct ether_header *const eh, struct ifnet *dst)
{
struct ifnet *src = (*m0)->m_pkthdr.rcvif; /* could be NULL in output */
struct ifnet *ifp, *last = NULL ;
int error=0, s ;
int canfree = 0 ; /* can free the buf at the end if set */
int once = 0; /* loop only once */
struct mbuf *m ;
if (dst == BDG_DROP) { /* this should not happen */
printf("xx bdg_forward for BDG_DROP\n");
m_freem(*m0) ;
*m0 = NULL ;
return 0;
}
if (dst == BDG_LOCAL) { /* this should not happen as well */
printf("xx ouch, bdg_forward for local pkt\n");
return 0;
}
if (dst == BDG_BCAST || dst == BDG_MCAST || dst == BDG_UNKNOWN) {
ifp = ifnet.tqh_first ; /* scan all ports */
once = 0 ;
if (dst != BDG_UNKNOWN) /* need a copy for the local stack */
canfree = 0 ;
} else {
ifp = dst ;
once = 1 ;
}
if ( (u_int)(ifp) <= (u_int)BDG_FORWARD )
panic("bdg_forward: bad dst");
#ifdef IPFIREWALL
/*
* do filtering in a very similar way to what is done
* in ip_output. Only for IP packets, and only pass/fail/dummynet
* is supported. The tricky thing is to make sure that enough of
* the packet (basically, Eth+IP+TCP/UDP headers) is contiguous
* so that calls to m_pullup in ip_fw_chk will not kill the
* ethernet header.
*/
if (ip_fw_chk_ptr) {
struct ip_fw_chain *rule = NULL ;
int off;
struct ip *ip ;
m = *m0 ;
#ifdef DUMMYNET
if (m->m_type == MT_DUMMYNET) {
/*
* the packet was already tagged, so part of the
* processing was already done, and we need to go down.
*/
rule = (struct ip_fw_chain *)(m->m_data) ;
(*m0) = m = m->m_next ;
src = m->m_pkthdr.rcvif; /* could be NULL in output */
canfree = 1 ; /* for sure, a copy is not needed later. */
goto forward; /* HACK! I should obey the fw_one_pass */
}
#endif
if (bdg_ipfw == 0) /* this test must be here. */
goto forward ;
if (src == NULL)
goto forward ; /* do not apply to packets from ether_output */
if (ntohs(eh->ether_type) != ETHERTYPE_IP)
goto forward ; /* not an IP packet, ipfw is not appropriate */
/*
* In this section, canfree=1 means m is the same as *m0.
* canfree==0 means m is a copy. We need to make a copy here
* (to be destroyed on exit from the firewall section) because
* the firewall itself might destroy the packet.
* (This is not very smart... i should really change ipfw to
* leave the pkt alive!)
*/
if (canfree == 0 ) {
/*
* Need to make a copy (and for good measure, make sure that
* the header is contiguous). The original is still in *m0
*/
int needed = min(MHLEN, max_protohdr) ;
needed = min(needed, (*m0)->m_len ) ;
m = m_copypacket( (*m0), M_DONTWAIT);
if (m == NULL) {
printf("-- bdg: m_copypacket failed.\n") ;
return ENOBUFS ;
}
if (m->m_len < needed && (m = m_pullup(m, needed)) == NULL) {
printf("-- bdg: pullup failed.\n") ;
return ENOBUFS ;
}
}
/*
* before calling the firewall, swap fields the same as IP does.
* here we assume the pkt is an IP one and the header is contiguous
*/
ip = mtod(m, struct ip *);
NTOHS(ip->ip_len);
NTOHS(ip->ip_id);
NTOHS(ip->ip_off);
/*
* The third parameter to the firewall code is the dst. interface.
* Since we apply checks only on input pkts we use NULL.
*/
off = (*ip_fw_chk_ptr)(&ip, 0, NULL, NULL, &m, &rule, NULL);
if (m == NULL) { /* pkt discarded by firewall */
/*
* At this point, if canfree==1, m and *m0 were the same
* thing, so just clear ptr. Otherwise, leave it alone, the
* upper layer might still make use of it somewhere.
*/
if (canfree)
*m0 = NULL ;
return 0 ;
}
/*
* If we get here, the firewall has passed the pkt, but the
* mbuf pointer might have changed. Restore the fields NTOHS()'d.
* Then, if canfree==1, also restore *m0.
*/
HTONS(ip->ip_len);
HTONS(ip->ip_id);
HTONS(ip->ip_off);
if (canfree) /* m was a reference to *m0, so update *m0 */
*m0 = m ;
if (off == 0) { /* a PASS rule. */
if (canfree == 0) /* destroy the copy */
m_freem(m);
goto forward ;
}
#ifdef DUMMYNET
if (off & 0x10000) {
/*
* pass the pkt to dummynet. Need to include m, dst, rule.
* Dummynet consumes the packet in all cases.
*/
dummynet_io((off & 0xffff), DN_TO_BDG_FWD, m, dst, NULL, 0, rule, 0);
if (canfree) /* dummynet has consumed the original one */
*m0 = NULL ;
return 0 ;
}
#endif
/*
* XXX add divert/forward actions...
*/
/* if none of the above matches, we have to drop the pkt */
bdg_ipfw_drops++ ;
m_freem(m);
if (canfree == 0) /* m was a copy */
m_freem(*m0);
*m0 = NULL ;
return 0 ;
}
forward:
#endif /* IPFIREWALL */
/*
* Now *m0 is the only pkt left. If canfree != 0 the pkt might be
* used by the upper layers which could scramble header fields.
* (basically ntoh*() etc.). To avoid problems, make sure that
* all fields that might be changed by the local network stack are not
* in a cluster by calling m_pullup on *m0. We lose some efficiency
* but better than having packets corrupt!
*/
if (canfree == 0 ) {
int needed = min(MHLEN, max_protohdr) ;
needed = min(needed, (*m0)->m_len ) ;
if ((*m0)->m_len < needed && (*m0 = m_pullup(*m0, needed)) == NULL) {
printf("-- bdg: pullup failed.\n") ;
return ENOBUFS ;
}
}
for (;;) {
if (last) { /* need to forward packet */
if (canfree && once ) { /* no need to copy */
m = *m0 ;
*m0 = NULL ; /* original is gone */
} else /* on a P5-90, m_copypacket takes 540 ticks */
m = m_copypacket(*m0, M_DONTWAIT);
if (m == NULL) {
printf("bdg_forward: sorry, m_copy failed!\n");
return ENOBUFS ; /* the original is still there... */
}
/*
* Last part of ether_output: add header, queue pkt and start
* output if interface not yet active.
*/
M_PREPEND(m, ETHER_HDR_LEN, M_DONTWAIT);
if (m == NULL)
return ENOBUFS;
bcopy(eh, mtod(m, struct ether_header *), ETHER_HDR_LEN);
s = splimp();
if (IF_QFULL(&last->if_snd)) {
IF_DROP(&last->if_snd);
#if 0
MUTE(last); /* should I also mute ? */
#endif
splx(s);
m_freem(m); /* consume the pkt anyways */
error = ENOBUFS ;
} else {
last->if_obytes += m->m_pkthdr.len ;
if (m->m_flags & M_MCAST)
last->if_omcasts++;
IF_ENQUEUE(&last->if_snd, m);
if ((last->if_flags & IFF_OACTIVE) == 0)
(*last->if_start)(last);
splx(s);
}
BDG_STAT(last, BDG_OUT);
last = NULL ;
if (once)
break ;
}
if (ifp == NULL)
break ;
if (ifp != src && /* do not send to self */
USED(ifp) && /* if used for bridging */
! IF_QFULL(&ifp->if_snd) &&
(ifp->if_flags & (IFF_UP|IFF_RUNNING)) ==
(IFF_UP|IFF_RUNNING) &&
SAMECLUSTER(ifp, src) && !MUTED(ifp) )
last = ifp ;
ifp = ifp->if_link.tqe_next ;
if (ifp == NULL)
once = 1 ;
}
return error ;
}
|