1 /*-
2 * Copyright (c) 1982, 1986, 1988, 1990, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)ip_output.c 8.3 (Berkeley) 1/21/94
30 */
31
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34
35 #include "opt_inet.h"
36 #include "opt_ipfw.h"
37 #include "opt_ipsec.h"
38 #include "opt_kdtrace.h"
39 #include "opt_mbuf_stress_test.h"
40 #include "opt_mpath.h"
41 #include "opt_route.h"
42 #include "opt_sctp.h"
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kernel.h>
47 #include <sys/malloc.h>
48 #include <sys/mbuf.h>
49 #include <sys/priv.h>
50 #include <sys/proc.h>
51 #include <sys/protosw.h>
52 #include <sys/sdt.h>
53 #include <sys/socket.h>
54 #include <sys/socketvar.h>
55 #include <sys/sysctl.h>
56 #include <sys/ucred.h>
57
58 #include <net/if.h>
59 #include <net/if_llatbl.h>
60 #include <net/netisr.h>
61 #include <net/pfil.h>
62 #include <net/route.h>
63 #include <net/flowtable.h>
64 #ifdef RADIX_MPATH
65 #include <net/radix_mpath.h>
66 #endif
67 #include <net/vnet.h>
68
69 #include <netinet/in.h>
70 #include <netinet/in_kdtrace.h>
71 #include <netinet/in_systm.h>
72 #include <netinet/ip.h>
73 #include <netinet/in_pcb.h>
74 #include <netinet/in_var.h>
75 #include <netinet/ip_var.h>
76 #include <netinet/ip_options.h>
77 #ifdef SCTP
78 #include <netinet/sctp.h>
79 #include <netinet/sctp_crc32.h>
80 #endif
81
82 #ifdef IPSEC
83 #include <netinet/ip_ipsec.h>
84 #include <netipsec/ipsec.h>
85 #endif /* IPSEC*/
86
87 #include <machine/in_cksum.h>
88
89 #include <security/mac/mac_framework.h>
90
91 VNET_DEFINE(u_short, ip_id);
92
93 #ifdef MBUF_STRESS_TEST
94 static int mbuf_frag_size = 0;
95 SYSCTL_INT(_net_inet_ip, OID_AUTO, mbuf_frag_size, CTLFLAG_RW,
96 &mbuf_frag_size, 0, "Fragment outgoing mbufs to this size");
97 #endif
98
99 static void ip_mloopback
100 (struct ifnet *, struct mbuf *, struct sockaddr_in *, int);
101
102
103 extern int in_mcast_loop;
104 extern struct protosw inetsw[];
105
106 /*
107 * IP output. The packet in mbuf chain m contains a skeletal IP
108 * header (with len, off, ttl, proto, tos, src, dst).
109 * The mbuf chain containing the packet will be freed.
110 * The mbuf opt, if present, will not be freed.
111 * If route ro is present and has ro_rt initialized, route lookup would be
112 * skipped and ro->ro_rt would be used. If ro is present but ro->ro_rt is NULL,
113 * then result of route lookup is stored in ro->ro_rt.
114 *
115 * In the IP forwarding case, the packet will arrive with options already
116 * inserted, so must have a NULL opt pointer.
117 */
118 int
ip_output(struct mbuf * m,struct mbuf * opt,struct route * ro,int flags,struct ip_moptions * imo,struct inpcb * inp)119 ip_output(struct mbuf *m, struct mbuf *opt, struct route *ro, int flags,
120 struct ip_moptions *imo, struct inpcb *inp)
121 {
122 struct ip *ip;
123 struct ifnet *ifp = NULL; /* keep compiler happy */
124 struct mbuf *m0;
125 int hlen = sizeof (struct ip);
126 int mtu;
127 int n; /* scratchpad */
128 int error = 0;
129 struct sockaddr_in *dst;
130 const struct sockaddr_in *gw;
131 struct in_ifaddr *ia;
132 int isbroadcast;
133 uint16_t ip_len, ip_off;
134 struct route iproute;
135 struct rtentry *rte; /* cache for ro->ro_rt */
136 struct in_addr odst;
137 struct m_tag *fwd_tag = NULL;
138 int have_ia_ref;
139 #ifdef IPSEC
140 int no_route_but_check_spd = 0;
141 #endif
142 M_ASSERTPKTHDR(m);
143
144 if (inp != NULL) {
145 INP_LOCK_ASSERT(inp);
146 M_SETFIB(m, inp->inp_inc.inc_fibnum);
147 if (inp->inp_flowtype != M_HASHTYPE_NONE) {
148 m->m_pkthdr.flowid = inp->inp_flowid;
149 M_HASHTYPE_SET(m, M_HASHTYPE_OPAQUE);
150 }
151 }
152
153 if (ro == NULL) {
154 ro = &iproute;
155 bzero(ro, sizeof (*ro));
156 }
157
158 #ifdef FLOWTABLE
159 if (ro->ro_rt == NULL)
160 (void )flowtable_lookup(AF_INET, m, ro);
161 #endif
162
163 if (opt) {
164 int len = 0;
165 m = ip_insertoptions(m, opt, &len);
166 if (len != 0)
167 hlen = len; /* ip->ip_hl is updated above */
168 }
169 ip = mtod(m, struct ip *);
170 ip_len = ntohs(ip->ip_len);
171 ip_off = ntohs(ip->ip_off);
172
173 /*
174 * Fill in IP header. If we are not allowing fragmentation,
175 * then the ip_id field is meaningless, but we don't set it
176 * to zero. Doing so causes various problems when devices along
177 * the path (routers, load balancers, firewalls, etc.) illegally
178 * disable DF on our packet. Note that a 16-bit counter
179 * will wrap around in less than 10 seconds at 100 Mbit/s on a
180 * medium with MTU 1500. See Steven M. Bellovin, "A Technique
181 * for Counting NATted Hosts", Proc. IMW'02, available at
182 * <http://www.cs.columbia.edu/~smb/papers/fnat.pdf>.
183 */
184 if ((flags & (IP_FORWARDING|IP_RAWOUTPUT)) == 0) {
185 ip->ip_v = IPVERSION;
186 ip->ip_hl = hlen >> 2;
187 ip->ip_id = ip_newid();
188 IPSTAT_INC(ips_localout);
189 } else {
190 /* Header already set, fetch hlen from there */
191 hlen = ip->ip_hl << 2;
192 }
193
194 /*
195 * dst/gw handling:
196 *
197 * dst can be rewritten but always point to &ro->ro_dst
198 * gw is readonly but can be pointed either to dst OR rt_gatewy
199 * therefore we need restore GW if we're re-doing lookup
200 */
201 gw = dst = (struct sockaddr_in *)&ro->ro_dst;
202 again:
203 ia = NULL;
204 have_ia_ref = 0;
205 /*
206 * If there is a cached route,
207 * check that it is to the same destination
208 * and is still up. If not, free it and try again.
209 * The address family should also be checked in case of sharing the
210 * cache with IPv6.
211 */
212 rte = ro->ro_rt;
213 if (rte && ((rte->rt_flags & RTF_UP) == 0 ||
214 rte->rt_ifp == NULL ||
215 !RT_LINK_IS_UP(rte->rt_ifp) ||
216 dst->sin_family != AF_INET ||
217 dst->sin_addr.s_addr != ip->ip_dst.s_addr)) {
218 RO_RTFREE(ro);
219 ro->ro_lle = NULL;
220 rte = NULL;
221 gw = dst;
222 }
223 if (rte == NULL && fwd_tag == NULL) {
224 bzero(dst, sizeof(*dst));
225 dst->sin_family = AF_INET;
226 dst->sin_len = sizeof(*dst);
227 dst->sin_addr = ip->ip_dst;
228 }
229 /*
230 * If routing to interface only, short circuit routing lookup.
231 * The use of an all-ones broadcast address implies this; an
232 * interface is specified by the broadcast address of an interface,
233 * or the destination address of a ptp interface.
234 */
235 if (flags & IP_SENDONES) {
236 if ((ia = ifatoia(ifa_ifwithbroadaddr(sintosa(dst)))) == NULL &&
237 (ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL) {
238 IPSTAT_INC(ips_noroute);
239 error = ENETUNREACH;
240 goto bad;
241 }
242 have_ia_ref = 1;
243 ip->ip_dst.s_addr = INADDR_BROADCAST;
244 dst->sin_addr = ip->ip_dst;
245 ifp = ia->ia_ifp;
246 ip->ip_ttl = 1;
247 isbroadcast = 1;
248 } else if (flags & IP_ROUTETOIF) {
249 if ((ia = ifatoia(ifa_ifwithdstaddr(sintosa(dst)))) == NULL &&
250 (ia = ifatoia(ifa_ifwithnet(sintosa(dst), 0))) == NULL) {
251 IPSTAT_INC(ips_noroute);
252 error = ENETUNREACH;
253 goto bad;
254 }
255 have_ia_ref = 1;
256 ifp = ia->ia_ifp;
257 ip->ip_ttl = 1;
258 isbroadcast = in_broadcast(dst->sin_addr, ifp);
259 } else if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) &&
260 imo != NULL && imo->imo_multicast_ifp != NULL) {
261 /*
262 * Bypass the normal routing lookup for multicast
263 * packets if the interface is specified.
264 */
265 ifp = imo->imo_multicast_ifp;
266 IFP_TO_IA(ifp, ia);
267 if (ia)
268 have_ia_ref = 1;
269 isbroadcast = 0; /* fool gcc */
270 } else {
271 /*
272 * We want to do any cloning requested by the link layer,
273 * as this is probably required in all cases for correct
274 * operation (as it is for ARP).
275 */
276 if (rte == NULL) {
277 #ifdef RADIX_MPATH
278 rtalloc_mpath_fib(ro,
279 ntohl(ip->ip_src.s_addr ^ ip->ip_dst.s_addr),
280 inp ? inp->inp_inc.inc_fibnum : M_GETFIB(m));
281 #else
282 in_rtalloc_ign(ro, 0,
283 inp ? inp->inp_inc.inc_fibnum : M_GETFIB(m));
284 #endif
285 rte = ro->ro_rt;
286 }
287 if (rte == NULL ||
288 rte->rt_ifp == NULL ||
289 !RT_LINK_IS_UP(rte->rt_ifp)) {
290 #ifdef IPSEC
291 /*
292 * There is no route for this packet, but it is
293 * possible that a matching SPD entry exists.
294 */
295 no_route_but_check_spd = 1;
296 mtu = 0; /* Silence GCC warning. */
297 goto sendit;
298 #endif
299 IPSTAT_INC(ips_noroute);
300 error = EHOSTUNREACH;
301 goto bad;
302 }
303 ia = ifatoia(rte->rt_ifa);
304 ifp = rte->rt_ifp;
305 counter_u64_add(rte->rt_pksent, 1);
306 if (rte->rt_flags & RTF_GATEWAY)
307 gw = (struct sockaddr_in *)rte->rt_gateway;
308 if (rte->rt_flags & RTF_HOST)
309 isbroadcast = (rte->rt_flags & RTF_BROADCAST);
310 else
311 isbroadcast = in_broadcast(gw->sin_addr, ifp);
312 }
313 /*
314 * Calculate MTU. If we have a route that is up, use that,
315 * otherwise use the interface's MTU.
316 */
317 if (rte != NULL && (rte->rt_flags & (RTF_UP|RTF_HOST))) {
318 /*
319 * This case can happen if the user changed the MTU
320 * of an interface after enabling IP on it. Because
321 * most netifs don't keep track of routes pointing to
322 * them, there is no way for one to update all its
323 * routes when the MTU is changed.
324 */
325 if (rte->rt_mtu > ifp->if_mtu)
326 rte->rt_mtu = ifp->if_mtu;
327 mtu = rte->rt_mtu;
328 } else {
329 mtu = ifp->if_mtu;
330 }
331 /* Catch a possible divide by zero later. */
332 KASSERT(mtu > 0, ("%s: mtu %d <= 0, rte=%p (rt_flags=0x%08x) ifp=%p",
333 __func__, mtu, rte, (rte != NULL) ? rte->rt_flags : 0, ifp));
334 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) {
335 m->m_flags |= M_MCAST;
336 /*
337 * IP destination address is multicast. Make sure "gw"
338 * still points to the address in "ro". (It may have been
339 * changed to point to a gateway address, above.)
340 */
341 gw = dst;
342 /*
343 * See if the caller provided any multicast options
344 */
345 if (imo != NULL) {
346 ip->ip_ttl = imo->imo_multicast_ttl;
347 if (imo->imo_multicast_vif != -1)
348 ip->ip_src.s_addr =
349 ip_mcast_src ?
350 ip_mcast_src(imo->imo_multicast_vif) :
351 INADDR_ANY;
352 } else
353 ip->ip_ttl = IP_DEFAULT_MULTICAST_TTL;
354 /*
355 * Confirm that the outgoing interface supports multicast.
356 */
357 if ((imo == NULL) || (imo->imo_multicast_vif == -1)) {
358 if ((ifp->if_flags & IFF_MULTICAST) == 0) {
359 IPSTAT_INC(ips_noroute);
360 error = ENETUNREACH;
361 goto bad;
362 }
363 }
364 /*
365 * If source address not specified yet, use address
366 * of outgoing interface.
367 */
368 if (ip->ip_src.s_addr == INADDR_ANY) {
369 /* Interface may have no addresses. */
370 if (ia != NULL)
371 ip->ip_src = IA_SIN(ia)->sin_addr;
372 }
373
374 if ((imo == NULL && in_mcast_loop) ||
375 (imo && imo->imo_multicast_loop)) {
376 /*
377 * Loop back multicast datagram if not expressly
378 * forbidden to do so, even if we are not a member
379 * of the group; ip_input() will filter it later,
380 * thus deferring a hash lookup and mutex acquisition
381 * at the expense of a cheap copy using m_copym().
382 */
383 ip_mloopback(ifp, m, dst, hlen);
384 } else {
385 /*
386 * If we are acting as a multicast router, perform
387 * multicast forwarding as if the packet had just
388 * arrived on the interface to which we are about
389 * to send. The multicast forwarding function
390 * recursively calls this function, using the
391 * IP_FORWARDING flag to prevent infinite recursion.
392 *
393 * Multicasts that are looped back by ip_mloopback(),
394 * above, will be forwarded by the ip_input() routine,
395 * if necessary.
396 */
397 if (V_ip_mrouter && (flags & IP_FORWARDING) == 0) {
398 /*
399 * If rsvp daemon is not running, do not
400 * set ip_moptions. This ensures that the packet
401 * is multicast and not just sent down one link
402 * as prescribed by rsvpd.
403 */
404 if (!V_rsvp_on)
405 imo = NULL;
406 if (ip_mforward &&
407 ip_mforward(ip, ifp, m, imo) != 0) {
408 m_freem(m);
409 goto done;
410 }
411 }
412 }
413
414 /*
415 * Multicasts with a time-to-live of zero may be looped-
416 * back, above, but must not be transmitted on a network.
417 * Also, multicasts addressed to the loopback interface
418 * are not sent -- the above call to ip_mloopback() will
419 * loop back a copy. ip_input() will drop the copy if
420 * this host does not belong to the destination group on
421 * the loopback interface.
422 */
423 if (ip->ip_ttl == 0 || ifp->if_flags & IFF_LOOPBACK) {
424 m_freem(m);
425 goto done;
426 }
427
428 goto sendit;
429 }
430
431 /*
432 * If the source address is not specified yet, use the address
433 * of the outoing interface.
434 */
435 if (ip->ip_src.s_addr == INADDR_ANY) {
436 /* Interface may have no addresses. */
437 if (ia != NULL) {
438 ip->ip_src = IA_SIN(ia)->sin_addr;
439 }
440 }
441
442 /*
443 * Verify that we have any chance at all of being able to queue the
444 * packet or packet fragments, unless ALTQ is enabled on the given
445 * interface in which case packetdrop should be done by queueing.
446 */
447 n = ip_len / mtu + 1; /* how many fragments ? */
448 if (
449 #ifdef ALTQ
450 (!ALTQ_IS_ENABLED(&ifp->if_snd)) &&
451 #endif /* ALTQ */
452 (ifp->if_snd.ifq_len + n) >= ifp->if_snd.ifq_maxlen ) {
453 error = ENOBUFS;
454 IPSTAT_INC(ips_odropped);
455 ifp->if_snd.ifq_drops += n;
456 goto bad;
457 }
458
459 /*
460 * Look for broadcast address and
461 * verify user is allowed to send
462 * such a packet.
463 */
464 if (isbroadcast) {
465 if ((ifp->if_flags & IFF_BROADCAST) == 0) {
466 error = EADDRNOTAVAIL;
467 goto bad;
468 }
469 if ((flags & IP_ALLOWBROADCAST) == 0) {
470 error = EACCES;
471 goto bad;
472 }
473 /* don't allow broadcast messages to be fragmented */
474 if (ip_len > mtu) {
475 error = EMSGSIZE;
476 goto bad;
477 }
478 m->m_flags |= M_BCAST;
479 } else {
480 m->m_flags &= ~M_BCAST;
481 }
482
483 sendit:
484 #ifdef IPSEC
485 switch(ip_ipsec_output(&m, inp, &flags, &error)) {
486 case 1:
487 goto bad;
488 case -1:
489 goto done;
490 case 0:
491 default:
492 break; /* Continue with packet processing. */
493 }
494 /*
495 * Check if there was a route for this packet; return error if not.
496 */
497 if (no_route_but_check_spd) {
498 IPSTAT_INC(ips_noroute);
499 error = EHOSTUNREACH;
500 goto bad;
501 }
502 /* Update variables that are affected by ipsec4_output(). */
503 ip = mtod(m, struct ip *);
504 hlen = ip->ip_hl << 2;
505 #endif /* IPSEC */
506
507 /* Jump over all PFIL processing if hooks are not active. */
508 if (!PFIL_HOOKED(&V_inet_pfil_hook))
509 goto passout;
510
511 /* Run through list of hooks for output packets. */
512 odst.s_addr = ip->ip_dst.s_addr;
513 error = pfil_run_hooks(&V_inet_pfil_hook, &m, ifp, PFIL_OUT, inp);
514 if (error != 0 || m == NULL)
515 goto done;
516
517 ip = mtod(m, struct ip *);
518
519 /* See if destination IP address was changed by packet filter. */
520 if (odst.s_addr != ip->ip_dst.s_addr) {
521 m->m_flags |= M_SKIP_FIREWALL;
522 /* If destination is now ourself drop to ip_input(). */
523 if (in_localip(ip->ip_dst)) {
524 m->m_flags |= M_FASTFWD_OURS;
525 if (m->m_pkthdr.rcvif == NULL)
526 m->m_pkthdr.rcvif = V_loif;
527 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
528 m->m_pkthdr.csum_flags |=
529 CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
530 m->m_pkthdr.csum_data = 0xffff;
531 }
532 m->m_pkthdr.csum_flags |=
533 CSUM_IP_CHECKED | CSUM_IP_VALID;
534 #ifdef SCTP
535 if (m->m_pkthdr.csum_flags & CSUM_SCTP)
536 m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
537 #endif
538 error = netisr_queue(NETISR_IP, m);
539 goto done;
540 } else {
541 if (have_ia_ref)
542 ifa_free(&ia->ia_ifa);
543 goto again; /* Redo the routing table lookup. */
544 }
545 }
546
547 /* See if local, if yes, send it to netisr with IP_FASTFWD_OURS. */
548 if (m->m_flags & M_FASTFWD_OURS) {
549 if (m->m_pkthdr.rcvif == NULL)
550 m->m_pkthdr.rcvif = V_loif;
551 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
552 m->m_pkthdr.csum_flags |=
553 CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
554 m->m_pkthdr.csum_data = 0xffff;
555 }
556 #ifdef SCTP
557 if (m->m_pkthdr.csum_flags & CSUM_SCTP)
558 m->m_pkthdr.csum_flags |= CSUM_SCTP_VALID;
559 #endif
560 m->m_pkthdr.csum_flags |=
561 CSUM_IP_CHECKED | CSUM_IP_VALID;
562
563 error = netisr_queue(NETISR_IP, m);
564 goto done;
565 }
566 /* Or forward to some other address? */
567 if ((m->m_flags & M_IP_NEXTHOP) &&
568 (fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL)) != NULL) {
569 bcopy((fwd_tag+1), dst, sizeof(struct sockaddr_in));
570 m->m_flags |= M_SKIP_FIREWALL;
571 m->m_flags &= ~M_IP_NEXTHOP;
572 m_tag_delete(m, fwd_tag);
573 if (have_ia_ref)
574 ifa_free(&ia->ia_ifa);
575 goto again;
576 }
577
578 passout:
579 /* 127/8 must not appear on wire - RFC1122. */
580 if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
581 (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
582 if ((ifp->if_flags & IFF_LOOPBACK) == 0) {
583 IPSTAT_INC(ips_badaddr);
584 error = EADDRNOTAVAIL;
585 goto bad;
586 }
587 }
588
589 m->m_pkthdr.csum_flags |= CSUM_IP;
590 if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA & ~ifp->if_hwassist) {
591 in_delayed_cksum(m);
592 m->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
593 }
594 #ifdef SCTP
595 if (m->m_pkthdr.csum_flags & CSUM_SCTP & ~ifp->if_hwassist) {
596 sctp_delayed_cksum(m, (uint32_t)(ip->ip_hl << 2));
597 m->m_pkthdr.csum_flags &= ~CSUM_SCTP;
598 }
599 #endif
600
601 /*
602 * If small enough for interface, or the interface will take
603 * care of the fragmentation for us, we can just send directly.
604 */
605 if (ip_len <= mtu ||
606 (m->m_pkthdr.csum_flags & ifp->if_hwassist & CSUM_TSO) != 0 ||
607 ((ip_off & IP_DF) == 0 && (ifp->if_hwassist & CSUM_FRAGMENT))) {
608 ip->ip_sum = 0;
609 if (m->m_pkthdr.csum_flags & CSUM_IP & ~ifp->if_hwassist) {
610 ip->ip_sum = in_cksum(m, hlen);
611 m->m_pkthdr.csum_flags &= ~CSUM_IP;
612 }
613
614 /*
615 * Record statistics for this interface address.
616 * With CSUM_TSO the byte/packet count will be slightly
617 * incorrect because we count the IP+TCP headers only
618 * once instead of for every generated packet.
619 */
620 if (!(flags & IP_FORWARDING) && ia) {
621 if (m->m_pkthdr.csum_flags & CSUM_TSO)
622 ia->ia_ifa.if_opackets +=
623 m->m_pkthdr.len / m->m_pkthdr.tso_segsz;
624 else
625 ia->ia_ifa.if_opackets++;
626 ia->ia_ifa.if_obytes += m->m_pkthdr.len;
627 }
628 #ifdef MBUF_STRESS_TEST
629 if (mbuf_frag_size && m->m_pkthdr.len > mbuf_frag_size)
630 m = m_fragment(m, M_NOWAIT, mbuf_frag_size);
631 #endif
632 /*
633 * Reset layer specific mbuf flags
634 * to avoid confusing lower layers.
635 */
636 m_clrprotoflags(m);
637 IP_PROBE(send, NULL, NULL, ip, ifp, ip, NULL);
638 error = (*ifp->if_output)(ifp, m,
639 (const struct sockaddr *)gw, ro);
640 goto done;
641 }
642
643 /* Balk when DF bit is set or the interface didn't support TSO. */
644 if ((ip_off & IP_DF) || (m->m_pkthdr.csum_flags & CSUM_TSO)) {
645 error = EMSGSIZE;
646 IPSTAT_INC(ips_cantfrag);
647 goto bad;
648 }
649
650 /*
651 * Too large for interface; fragment if possible. If successful,
652 * on return, m will point to a list of packets to be sent.
653 */
654 error = ip_fragment(ip, &m, mtu, ifp->if_hwassist);
655 if (error)
656 goto bad;
657 for (; m; m = m0) {
658 m0 = m->m_nextpkt;
659 m->m_nextpkt = 0;
660 if (error == 0) {
661 /* Record statistics for this interface address. */
662 if (ia != NULL) {
663 ia->ia_ifa.if_opackets++;
664 ia->ia_ifa.if_obytes += m->m_pkthdr.len;
665 }
666 /*
667 * Reset layer specific mbuf flags
668 * to avoid confusing upper layers.
669 */
670 m_clrprotoflags(m);
671
672 IP_PROBE(send, NULL, NULL, ip, ifp, ip, NULL);
673 error = (*ifp->if_output)(ifp, m,
674 (const struct sockaddr *)gw, ro);
675 } else
676 m_freem(m);
677 }
678
679 if (error == 0)
680 IPSTAT_INC(ips_fragmented);
681
682 done:
683 if (ro == &iproute)
684 RO_RTFREE(ro);
685 if (have_ia_ref)
686 ifa_free(&ia->ia_ifa);
687 return (error);
688 bad:
689 m_freem(m);
690 goto done;
691 }
692
693 /*
694 * Create a chain of fragments which fit the given mtu. m_frag points to the
695 * mbuf to be fragmented; on return it points to the chain with the fragments.
696 * Return 0 if no error. If error, m_frag may contain a partially built
697 * chain of fragments that should be freed by the caller.
698 *
699 * if_hwassist_flags is the hw offload capabilities (see if_data.ifi_hwassist)
700 */
701 int
ip_fragment(struct ip * ip,struct mbuf ** m_frag,int mtu,u_long if_hwassist_flags)702 ip_fragment(struct ip *ip, struct mbuf **m_frag, int mtu,
703 u_long if_hwassist_flags)
704 {
705 int error = 0;
706 int hlen = ip->ip_hl << 2;
707 int len = (mtu - hlen) & ~7; /* size of payload in each fragment */
708 int off;
709 struct mbuf *m0 = *m_frag; /* the original packet */
710 int firstlen;
711 struct mbuf **mnext;
712 int nfrags;
713 uint16_t ip_len, ip_off;
714
715 ip_len = ntohs(ip->ip_len);
716 ip_off = ntohs(ip->ip_off);
717
718 if (ip_off & IP_DF) { /* Fragmentation not allowed */
719 IPSTAT_INC(ips_cantfrag);
720 return EMSGSIZE;
721 }
722
723 /*
724 * Must be able to put at least 8 bytes per fragment.
725 */
726 if (len < 8)
727 return EMSGSIZE;
728
729 /*
730 * If the interface will not calculate checksums on
731 * fragmented packets, then do it here.
732 */
733 if (m0->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
734 in_delayed_cksum(m0);
735 m0->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
736 }
737 #ifdef SCTP
738 if (m0->m_pkthdr.csum_flags & CSUM_SCTP) {
739 sctp_delayed_cksum(m0, hlen);
740 m0->m_pkthdr.csum_flags &= ~CSUM_SCTP;
741 }
742 #endif
743 if (len > PAGE_SIZE) {
744 /*
745 * Fragment large datagrams such that each segment
746 * contains a multiple of PAGE_SIZE amount of data,
747 * plus headers. This enables a receiver to perform
748 * page-flipping zero-copy optimizations.
749 *
750 * XXX When does this help given that sender and receiver
751 * could have different page sizes, and also mtu could
752 * be less than the receiver's page size ?
753 */
754 int newlen;
755
756 off = MIN(mtu, m0->m_pkthdr.len);
757
758 /*
759 * firstlen (off - hlen) must be aligned on an
760 * 8-byte boundary
761 */
762 if (off < hlen)
763 goto smart_frag_failure;
764 off = ((off - hlen) & ~7) + hlen;
765 newlen = (~PAGE_MASK) & mtu;
766 if ((newlen + sizeof (struct ip)) > mtu) {
767 /* we failed, go back the default */
768 smart_frag_failure:
769 newlen = len;
770 off = hlen + len;
771 }
772 len = newlen;
773
774 } else {
775 off = hlen + len;
776 }
777
778 firstlen = off - hlen;
779 mnext = &m0->m_nextpkt; /* pointer to next packet */
780
781 /*
782 * Loop through length of segment after first fragment,
783 * make new header and copy data of each part and link onto chain.
784 * Here, m0 is the original packet, m is the fragment being created.
785 * The fragments are linked off the m_nextpkt of the original
786 * packet, which after processing serves as the first fragment.
787 */
788 for (nfrags = 1; off < ip_len; off += len, nfrags++) {
789 struct ip *mhip; /* ip header on the fragment */
790 struct mbuf *m;
791 int mhlen = sizeof (struct ip);
792
793 m = m_gethdr(M_NOWAIT, MT_DATA);
794 if (m == NULL) {
795 error = ENOBUFS;
796 IPSTAT_INC(ips_odropped);
797 goto done;
798 }
799 /*
800 * make sure the flowid and flowtype are the same for the
801 * fragmented mbufs
802 */
803 M_HASHTYPE_SET(m, M_HASHTYPE_GET(m0));
804 m->m_pkthdr.flowid = m0->m_pkthdr.flowid;
805 /* copy multicast flags, if any */
806 m->m_flags |= (m0->m_flags & M_MCAST);
807 /*
808 * In the first mbuf, leave room for the link header, then
809 * copy the original IP header including options. The payload
810 * goes into an additional mbuf chain returned by m_copym().
811 */
812 m->m_data += max_linkhdr;
813 mhip = mtod(m, struct ip *);
814 *mhip = *ip;
815 if (hlen > sizeof (struct ip)) {
816 mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
817 mhip->ip_v = IPVERSION;
818 mhip->ip_hl = mhlen >> 2;
819 }
820 m->m_len = mhlen;
821 /* XXX do we need to add ip_off below ? */
822 mhip->ip_off = ((off - hlen) >> 3) + ip_off;
823 if (off + len >= ip_len)
824 len = ip_len - off;
825 else
826 mhip->ip_off |= IP_MF;
827 mhip->ip_len = htons((u_short)(len + mhlen));
828 m->m_next = m_copym(m0, off, len, M_NOWAIT);
829 if (m->m_next == NULL) { /* copy failed */
830 m_free(m);
831 error = ENOBUFS; /* ??? */
832 IPSTAT_INC(ips_odropped);
833 goto done;
834 }
835 m->m_pkthdr.len = mhlen + len;
836 m->m_pkthdr.rcvif = NULL;
837 #ifdef MAC
838 mac_netinet_fragment(m0, m);
839 #endif
840 m->m_pkthdr.csum_flags = m0->m_pkthdr.csum_flags;
841 mhip->ip_off = htons(mhip->ip_off);
842 mhip->ip_sum = 0;
843 if (m->m_pkthdr.csum_flags & CSUM_IP & ~if_hwassist_flags) {
844 mhip->ip_sum = in_cksum(m, mhlen);
845 m->m_pkthdr.csum_flags &= ~CSUM_IP;
846 }
847 *mnext = m;
848 mnext = &m->m_nextpkt;
849 }
850 IPSTAT_ADD(ips_ofragments, nfrags);
851
852 /*
853 * Update first fragment by trimming what's been copied out
854 * and updating header.
855 */
856 m_adj(m0, hlen + firstlen - ip_len);
857 m0->m_pkthdr.len = hlen + firstlen;
858 ip->ip_len = htons((u_short)m0->m_pkthdr.len);
859 ip->ip_off = htons(ip_off | IP_MF);
860 ip->ip_sum = 0;
861 if (m0->m_pkthdr.csum_flags & CSUM_IP & ~if_hwassist_flags) {
862 ip->ip_sum = in_cksum(m0, hlen);
863 m0->m_pkthdr.csum_flags &= ~CSUM_IP;
864 }
865
866 done:
867 *m_frag = m0;
868 return error;
869 }
870
871 void
in_delayed_cksum(struct mbuf * m)872 in_delayed_cksum(struct mbuf *m)
873 {
874 struct ip *ip;
875 uint16_t csum, offset, ip_len;
876
877 ip = mtod(m, struct ip *);
878 offset = ip->ip_hl << 2 ;
879 ip_len = ntohs(ip->ip_len);
880 csum = in_cksum_skip(m, ip_len, offset);
881 if (m->m_pkthdr.csum_flags & CSUM_UDP && csum == 0)
882 csum = 0xffff;
883 offset += m->m_pkthdr.csum_data; /* checksum offset */
884
885 /* find the mbuf in the chain where the checksum starts*/
886 while ((m != NULL) && (offset >= m->m_len)) {
887 offset -= m->m_len;
888 m = m->m_next;
889 }
890 KASSERT(m != NULL, ("in_delayed_cksum: checksum outside mbuf chain."));
891 KASSERT(offset + sizeof(u_short) <= m->m_len, ("in_delayed_cksum: checksum split between mbufs."));
892 *(u_short *)(m->m_data + offset) = csum;
893 }
894
895 /*
896 * IP socket option processing.
897 */
898 int
ip_ctloutput(struct socket * so,struct sockopt * sopt)899 ip_ctloutput(struct socket *so, struct sockopt *sopt)
900 {
901 struct inpcb *inp = sotoinpcb(so);
902 int error, optval;
903
904 error = optval = 0;
905 if (sopt->sopt_level != IPPROTO_IP) {
906 error = EINVAL;
907
908 if (sopt->sopt_level == SOL_SOCKET &&
909 sopt->sopt_dir == SOPT_SET) {
910 switch (sopt->sopt_name) {
911 case SO_REUSEADDR:
912 INP_WLOCK(inp);
913 if ((so->so_options & SO_REUSEADDR) != 0)
914 inp->inp_flags2 |= INP_REUSEADDR;
915 else
916 inp->inp_flags2 &= ~INP_REUSEADDR;
917 INP_WUNLOCK(inp);
918 error = 0;
919 break;
920 case SO_REUSEPORT:
921 INP_WLOCK(inp);
922 if ((so->so_options & SO_REUSEPORT) != 0)
923 inp->inp_flags2 |= INP_REUSEPORT;
924 else
925 inp->inp_flags2 &= ~INP_REUSEPORT;
926 INP_WUNLOCK(inp);
927 error = 0;
928 break;
929 case SO_SETFIB:
930 INP_WLOCK(inp);
931 inp->inp_inc.inc_fibnum = so->so_fibnum;
932 INP_WUNLOCK(inp);
933 error = 0;
934 break;
935 default:
936 break;
937 }
938 }
939 return (error);
940 }
941
942 switch (sopt->sopt_dir) {
943 case SOPT_SET:
944 switch (sopt->sopt_name) {
945 case IP_OPTIONS:
946 #ifdef notyet
947 case IP_RETOPTS:
948 #endif
949 {
950 struct mbuf *m;
951 if (sopt->sopt_valsize > MLEN) {
952 error = EMSGSIZE;
953 break;
954 }
955 m = m_get(sopt->sopt_td ? M_WAITOK : M_NOWAIT, MT_DATA);
956 if (m == NULL) {
957 error = ENOBUFS;
958 break;
959 }
960 m->m_len = sopt->sopt_valsize;
961 error = sooptcopyin(sopt, mtod(m, char *), m->m_len,
962 m->m_len);
963 if (error) {
964 m_free(m);
965 break;
966 }
967 INP_WLOCK(inp);
968 error = ip_pcbopts(inp, sopt->sopt_name, m);
969 INP_WUNLOCK(inp);
970 return (error);
971 }
972
973 case IP_BINDANY:
974 if (sopt->sopt_td != NULL) {
975 error = priv_check(sopt->sopt_td,
976 PRIV_NETINET_BINDANY);
977 if (error)
978 break;
979 }
980 /* FALLTHROUGH */
981 case IP_TOS:
982 case IP_TTL:
983 case IP_MINTTL:
984 case IP_RECVOPTS:
985 case IP_RECVRETOPTS:
986 case IP_RECVDSTADDR:
987 case IP_RECVTTL:
988 case IP_RECVIF:
989 case IP_FAITH:
990 case IP_ONESBCAST:
991 case IP_DONTFRAG:
992 case IP_RECVTOS:
993 error = sooptcopyin(sopt, &optval, sizeof optval,
994 sizeof optval);
995 if (error)
996 break;
997
998 switch (sopt->sopt_name) {
999 case IP_TOS:
1000 inp->inp_ip_tos = optval;
1001 break;
1002
1003 case IP_TTL:
1004 inp->inp_ip_ttl = optval;
1005 break;
1006
1007 case IP_MINTTL:
1008 if (optval >= 0 && optval <= MAXTTL)
1009 inp->inp_ip_minttl = optval;
1010 else
1011 error = EINVAL;
1012 break;
1013
1014 #define OPTSET(bit) do { \
1015 INP_WLOCK(inp); \
1016 if (optval) \
1017 inp->inp_flags |= bit; \
1018 else \
1019 inp->inp_flags &= ~bit; \
1020 INP_WUNLOCK(inp); \
1021 } while (0)
1022
1023 case IP_RECVOPTS:
1024 OPTSET(INP_RECVOPTS);
1025 break;
1026
1027 case IP_RECVRETOPTS:
1028 OPTSET(INP_RECVRETOPTS);
1029 break;
1030
1031 case IP_RECVDSTADDR:
1032 OPTSET(INP_RECVDSTADDR);
1033 break;
1034
1035 case IP_RECVTTL:
1036 OPTSET(INP_RECVTTL);
1037 break;
1038
1039 case IP_RECVIF:
1040 OPTSET(INP_RECVIF);
1041 break;
1042
1043 case IP_FAITH:
1044 OPTSET(INP_FAITH);
1045 break;
1046
1047 case IP_ONESBCAST:
1048 OPTSET(INP_ONESBCAST);
1049 break;
1050 case IP_DONTFRAG:
1051 OPTSET(INP_DONTFRAG);
1052 break;
1053 case IP_BINDANY:
1054 OPTSET(INP_BINDANY);
1055 break;
1056 case IP_RECVTOS:
1057 OPTSET(INP_RECVTOS);
1058 break;
1059 }
1060 break;
1061 #undef OPTSET
1062
1063 /*
1064 * Multicast socket options are processed by the in_mcast
1065 * module.
1066 */
1067 case IP_MULTICAST_IF:
1068 case IP_MULTICAST_VIF:
1069 case IP_MULTICAST_TTL:
1070 case IP_MULTICAST_LOOP:
1071 case IP_ADD_MEMBERSHIP:
1072 case IP_DROP_MEMBERSHIP:
1073 case IP_ADD_SOURCE_MEMBERSHIP:
1074 case IP_DROP_SOURCE_MEMBERSHIP:
1075 case IP_BLOCK_SOURCE:
1076 case IP_UNBLOCK_SOURCE:
1077 case IP_MSFILTER:
1078 case MCAST_JOIN_GROUP:
1079 case MCAST_LEAVE_GROUP:
1080 case MCAST_JOIN_SOURCE_GROUP:
1081 case MCAST_LEAVE_SOURCE_GROUP:
1082 case MCAST_BLOCK_SOURCE:
1083 case MCAST_UNBLOCK_SOURCE:
1084 error = inp_setmoptions(inp, sopt);
1085 break;
1086
1087 case IP_PORTRANGE:
1088 error = sooptcopyin(sopt, &optval, sizeof optval,
1089 sizeof optval);
1090 if (error)
1091 break;
1092
1093 INP_WLOCK(inp);
1094 switch (optval) {
1095 case IP_PORTRANGE_DEFAULT:
1096 inp->inp_flags &= ~(INP_LOWPORT);
1097 inp->inp_flags &= ~(INP_HIGHPORT);
1098 break;
1099
1100 case IP_PORTRANGE_HIGH:
1101 inp->inp_flags &= ~(INP_LOWPORT);
1102 inp->inp_flags |= INP_HIGHPORT;
1103 break;
1104
1105 case IP_PORTRANGE_LOW:
1106 inp->inp_flags &= ~(INP_HIGHPORT);
1107 inp->inp_flags |= INP_LOWPORT;
1108 break;
1109
1110 default:
1111 error = EINVAL;
1112 break;
1113 }
1114 INP_WUNLOCK(inp);
1115 break;
1116
1117 #ifdef IPSEC
1118 case IP_IPSEC_POLICY:
1119 {
1120 caddr_t req;
1121 struct mbuf *m;
1122
1123 if ((error = soopt_getm(sopt, &m)) != 0) /* XXX */
1124 break;
1125 if ((error = soopt_mcopyin(sopt, m)) != 0) /* XXX */
1126 break;
1127 req = mtod(m, caddr_t);
1128 error = ipsec_set_policy(inp, sopt->sopt_name, req,
1129 m->m_len, (sopt->sopt_td != NULL) ?
1130 sopt->sopt_td->td_ucred : NULL);
1131 m_freem(m);
1132 break;
1133 }
1134 #endif /* IPSEC */
1135
1136 default:
1137 error = ENOPROTOOPT;
1138 break;
1139 }
1140 break;
1141
1142 case SOPT_GET:
1143 switch (sopt->sopt_name) {
1144 case IP_OPTIONS:
1145 case IP_RETOPTS:
1146 if (inp->inp_options)
1147 error = sooptcopyout(sopt,
1148 mtod(inp->inp_options,
1149 char *),
1150 inp->inp_options->m_len);
1151 else
1152 sopt->sopt_valsize = 0;
1153 break;
1154
1155 case IP_TOS:
1156 case IP_TTL:
1157 case IP_MINTTL:
1158 case IP_RECVOPTS:
1159 case IP_RECVRETOPTS:
1160 case IP_RECVDSTADDR:
1161 case IP_RECVTTL:
1162 case IP_RECVIF:
1163 case IP_PORTRANGE:
1164 case IP_FAITH:
1165 case IP_ONESBCAST:
1166 case IP_DONTFRAG:
1167 case IP_BINDANY:
1168 case IP_RECVTOS:
1169 switch (sopt->sopt_name) {
1170
1171 case IP_TOS:
1172 optval = inp->inp_ip_tos;
1173 break;
1174
1175 case IP_TTL:
1176 optval = inp->inp_ip_ttl;
1177 break;
1178
1179 case IP_MINTTL:
1180 optval = inp->inp_ip_minttl;
1181 break;
1182
1183 #define OPTBIT(bit) (inp->inp_flags & bit ? 1 : 0)
1184
1185 case IP_RECVOPTS:
1186 optval = OPTBIT(INP_RECVOPTS);
1187 break;
1188
1189 case IP_RECVRETOPTS:
1190 optval = OPTBIT(INP_RECVRETOPTS);
1191 break;
1192
1193 case IP_RECVDSTADDR:
1194 optval = OPTBIT(INP_RECVDSTADDR);
1195 break;
1196
1197 case IP_RECVTTL:
1198 optval = OPTBIT(INP_RECVTTL);
1199 break;
1200
1201 case IP_RECVIF:
1202 optval = OPTBIT(INP_RECVIF);
1203 break;
1204
1205 case IP_PORTRANGE:
1206 if (inp->inp_flags & INP_HIGHPORT)
1207 optval = IP_PORTRANGE_HIGH;
1208 else if (inp->inp_flags & INP_LOWPORT)
1209 optval = IP_PORTRANGE_LOW;
1210 else
1211 optval = 0;
1212 break;
1213
1214 case IP_FAITH:
1215 optval = OPTBIT(INP_FAITH);
1216 break;
1217
1218 case IP_ONESBCAST:
1219 optval = OPTBIT(INP_ONESBCAST);
1220 break;
1221 case IP_DONTFRAG:
1222 optval = OPTBIT(INP_DONTFRAG);
1223 break;
1224 case IP_BINDANY:
1225 optval = OPTBIT(INP_BINDANY);
1226 break;
1227 case IP_RECVTOS:
1228 optval = OPTBIT(INP_RECVTOS);
1229 break;
1230 }
1231 error = sooptcopyout(sopt, &optval, sizeof optval);
1232 break;
1233
1234 /*
1235 * Multicast socket options are processed by the in_mcast
1236 * module.
1237 */
1238 case IP_MULTICAST_IF:
1239 case IP_MULTICAST_VIF:
1240 case IP_MULTICAST_TTL:
1241 case IP_MULTICAST_LOOP:
1242 case IP_MSFILTER:
1243 error = inp_getmoptions(inp, sopt);
1244 break;
1245
1246 #ifdef IPSEC
1247 case IP_IPSEC_POLICY:
1248 {
1249 struct mbuf *m = NULL;
1250 caddr_t req = NULL;
1251 size_t len = 0;
1252
1253 if (m != 0) {
1254 req = mtod(m, caddr_t);
1255 len = m->m_len;
1256 }
1257 error = ipsec_get_policy(sotoinpcb(so), req, len, &m);
1258 if (error == 0)
1259 error = soopt_mcopyout(sopt, m); /* XXX */
1260 if (error == 0)
1261 m_freem(m);
1262 break;
1263 }
1264 #endif /* IPSEC */
1265
1266 default:
1267 error = ENOPROTOOPT;
1268 break;
1269 }
1270 break;
1271 }
1272 return (error);
1273 }
1274
1275 /*
1276 * Routine called from ip_output() to loop back a copy of an IP multicast
1277 * packet to the input queue of a specified interface. Note that this
1278 * calls the output routine of the loopback "driver", but with an interface
1279 * pointer that might NOT be a loopback interface -- evil, but easier than
1280 * replicating that code here.
1281 */
1282 static void
ip_mloopback(struct ifnet * ifp,struct mbuf * m,struct sockaddr_in * dst,int hlen)1283 ip_mloopback(struct ifnet *ifp, struct mbuf *m, struct sockaddr_in *dst,
1284 int hlen)
1285 {
1286 register struct ip *ip;
1287 struct mbuf *copym;
1288
1289 /*
1290 * Make a deep copy of the packet because we're going to
1291 * modify the pack in order to generate checksums.
1292 */
1293 copym = m_dup(m, M_NOWAIT);
1294 if (copym != NULL && (copym->m_flags & M_EXT || copym->m_len < hlen))
1295 copym = m_pullup(copym, hlen);
1296 if (copym != NULL) {
1297 /* If needed, compute the checksum and mark it as valid. */
1298 if (copym->m_pkthdr.csum_flags & CSUM_DELAY_DATA) {
1299 in_delayed_cksum(copym);
1300 copym->m_pkthdr.csum_flags &= ~CSUM_DELAY_DATA;
1301 copym->m_pkthdr.csum_flags |=
1302 CSUM_DATA_VALID | CSUM_PSEUDO_HDR;
1303 copym->m_pkthdr.csum_data = 0xffff;
1304 }
1305 /*
1306 * We don't bother to fragment if the IP length is greater
1307 * than the interface's MTU. Can this possibly matter?
1308 */
1309 ip = mtod(copym, struct ip *);
1310 ip->ip_sum = 0;
1311 ip->ip_sum = in_cksum(copym, hlen);
1312 #if 1 /* XXX */
1313 if (dst->sin_family != AF_INET) {
1314 printf("ip_mloopback: bad address family %d\n",
1315 dst->sin_family);
1316 dst->sin_family = AF_INET;
1317 }
1318 #endif
1319 if_simloop(ifp, copym, dst->sin_family, 0);
1320 }
1321 }
1322