1/*
2 * Copyright (c) 1982, 1986, 1988, 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 * 3. 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_input.c	8.2 (Berkeley) 1/4/94
30 * ip_input.c,v 1.11 1994/11/16 10:17:08 jkh Exp
31 */
32
33/*
34 * Changes and additions relating to SLiRP are
35 * Copyright (c) 1995 Danny Gasparovski.
36 *
37 * Please read the file COPYRIGHT for the
38 * terms and conditions of the copyright.
39 */
40
41#include <slirp.h>
42#include <osdep.h>
43#include "ip_icmp.h"
44
45#ifdef LOG_ENABLED
46struct ipstat ipstat;
47#endif
48
49struct ipq ipq;
50
51static struct ip *ip_reass(register struct ip *ip,
52                           register struct ipq *fp);
53static void ip_freef(struct ipq *fp);
54static void ip_enq(register struct ipasfrag *p,
55                   register struct ipasfrag *prev);
56static void ip_deq(register struct ipasfrag *p);
57
58/*
59 * IP initialization: fill in IP protocol switch table.
60 * All protocols not implemented in kernel go to raw IP protocol handler.
61 */
62void
63ip_init(void)
64{
65	ipq.ip_link.next = ipq.ip_link.prev = &ipq.ip_link;
66	ip_id = tt.tv_sec & 0xffff;
67	udp_init();
68	tcp_init();
69}
70
71/*
72 * Ip input routine.  Checksum and byte swap header.  If fragmented
73 * try to reassemble.  Process options.  Pass to next level.
74 */
75void
76ip_input(struct mbuf *m)
77{
78	register struct ip *ip;
79	int hlen;
80
81	DEBUG_CALL("ip_input");
82	DEBUG_ARG("m = %lx", (long)m);
83	DEBUG_ARG("m_len = %d", m->m_len);
84
85	STAT(ipstat.ips_total++);
86
87	if (m->m_len < sizeof (struct ip)) {
88		STAT(ipstat.ips_toosmall++);
89		return;
90	}
91
92	ip = mtod(m, struct ip *);
93
94	if (ip->ip_v != IPVERSION) {
95		STAT(ipstat.ips_badvers++);
96		goto bad;
97	}
98
99	hlen = ip->ip_hl << 2;
100	if (hlen<sizeof(struct ip ) || hlen>m->m_len) {/* min header length */
101	  STAT(ipstat.ips_badhlen++);                     /* or packet too short */
102	  goto bad;
103	}
104
105        /* keep ip header intact for ICMP reply
106	 * ip->ip_sum = cksum(m, hlen);
107	 * if (ip->ip_sum) {
108	 */
109	if(cksum(m,hlen)) {
110	  STAT(ipstat.ips_badsum++);
111	  goto bad;
112	}
113
114	/*
115	 * Convert fields to host representation.
116	 */
117	NTOHS(ip->ip_len);
118	if (ip->ip_len < hlen) {
119		STAT(ipstat.ips_badlen++);
120		goto bad;
121	}
122	NTOHS(ip->ip_id);
123	NTOHS(ip->ip_off);
124
125	/*
126	 * Check that the amount of data in the buffers
127	 * is as at least much as the IP header would have us expect.
128	 * Trim mbufs if longer than we expect.
129	 * Drop packet if shorter than we expect.
130	 */
131	if (m->m_len < ip->ip_len) {
132		STAT(ipstat.ips_tooshort++);
133		goto bad;
134	}
135
136    if (slirp_restrict) {
137        if (memcmp(&ip->ip_dst.s_addr, &special_addr, 3)) {
138            if (ip->ip_dst.s_addr == 0xffffffff && ip->ip_p != IPPROTO_UDP)
139                goto bad;
140        } else {
141            int host = ntohl(ip->ip_dst.s_addr) & 0xff;
142            struct ex_list *ex_ptr;
143
144            if (host == 0xff)
145                goto bad;
146
147            for (ex_ptr = exec_list; ex_ptr; ex_ptr = ex_ptr->ex_next)
148                if (ex_ptr->ex_addr == host)
149                    break;
150
151            if (!ex_ptr)
152                goto bad;
153        }
154    }
155
156	/* Should drop packet if mbuf too long? hmmm... */
157	if (m->m_len > ip->ip_len)
158	   m_adj(m, ip->ip_len - m->m_len);
159
160	/* check ip_ttl for a correct ICMP reply */
161	if(ip->ip_ttl==0 || ip->ip_ttl==1) {
162	  icmp_error(m, ICMP_TIMXCEED,ICMP_TIMXCEED_INTRANS, 0,"ttl");
163	  goto bad;
164	}
165
166	/*
167	 * Process options and, if not destined for us,
168	 * ship it on.  ip_dooptions returns 1 when an
169	 * error was detected (causing an icmp message
170	 * to be sent and the original packet to be freed).
171	 */
172/* We do no IP options */
173/*	if (hlen > sizeof (struct ip) && ip_dooptions(m))
174 *		goto next;
175 */
176	/*
177	 * If offset or IP_MF are set, must reassemble.
178	 * Otherwise, nothing need be done.
179	 * (We could look in the reassembly queue to see
180	 * if the packet was previously fragmented,
181	 * but it's not worth the time; just let them time out.)
182	 *
183	 * XXX This should fail, don't fragment yet
184	 */
185	if (ip->ip_off &~ IP_DF) {
186	  register struct ipq *fp;
187      struct qlink *l;
188		/*
189		 * Look for queue of fragments
190		 * of this datagram.
191		 */
192		for (l = ipq.ip_link.next; l != &ipq.ip_link; l = l->next) {
193            fp = container_of(l, struct ipq, ip_link);
194            if (ip->ip_id == fp->ipq_id &&
195                    ip->ip_src.s_addr == fp->ipq_src.s_addr &&
196                    ip->ip_dst.s_addr == fp->ipq_dst.s_addr &&
197                    ip->ip_p == fp->ipq_p)
198		    goto found;
199        }
200        fp = NULL;
201	found:
202
203		/*
204		 * Adjust ip_len to not reflect header,
205		 * set ip_mff if more fragments are expected,
206		 * convert offset of this to bytes.
207		 */
208		ip->ip_len -= hlen;
209		if (ip->ip_off & IP_MF)
210		  ip->ip_tos |= 1;
211		else
212		  ip->ip_tos &= ~1;
213
214		ip->ip_off <<= 3;
215
216		/*
217		 * If datagram marked as having more fragments
218		 * or if this is not the first fragment,
219		 * attempt reassembly; if it succeeds, proceed.
220		 */
221		if (ip->ip_tos & 1 || ip->ip_off) {
222			STAT(ipstat.ips_fragments++);
223			ip = ip_reass(ip, fp);
224                        if (ip == NULL)
225				return;
226			STAT(ipstat.ips_reassembled++);
227			m = dtom(ip);
228		} else
229			if (fp)
230		   	   ip_freef(fp);
231
232	} else
233		ip->ip_len -= hlen;
234
235	/*
236	 * Switch out to protocol's input routine.
237	 */
238	STAT(ipstat.ips_delivered++);
239	switch (ip->ip_p) {
240	 case IPPROTO_TCP:
241		tcp_input(m, hlen, (struct socket *)NULL);
242		break;
243	 case IPPROTO_UDP:
244		udp_input(m, hlen);
245		break;
246	 case IPPROTO_ICMP:
247		icmp_input(m, hlen);
248		break;
249	 default:
250		STAT(ipstat.ips_noproto++);
251		m_free(m);
252	}
253	return;
254bad:
255	m_freem(m);
256	return;
257}
258
259#define iptofrag(P) ((struct ipasfrag *)(((char*)(P)) - sizeof(struct qlink)))
260#define fragtoip(P) ((struct ip*)(((char*)(P)) + sizeof(struct qlink)))
261/*
262 * Take incoming datagram fragment and try to
263 * reassemble it into whole datagram.  If a chain for
264 * reassembly of this datagram already exists, then it
265 * is given as fp; otherwise have to make a chain.
266 */
267static struct ip *
268ip_reass(register struct ip *ip, register struct ipq *fp)
269{
270	register struct mbuf *m = dtom(ip);
271	register struct ipasfrag *q;
272	int hlen = ip->ip_hl << 2;
273	int i, next;
274
275	DEBUG_CALL("ip_reass");
276	DEBUG_ARG("ip = %lx", (long)ip);
277	DEBUG_ARG("fp = %lx", (long)fp);
278	DEBUG_ARG("m = %lx", (long)m);
279
280	/*
281	 * Presence of header sizes in mbufs
282	 * would confuse code below.
283         * Fragment m_data is concatenated.
284	 */
285	m->m_data += hlen;
286	m->m_len -= hlen;
287
288	/*
289	 * If first fragment to arrive, create a reassembly queue.
290	 */
291        if (fp == NULL) {
292	  struct mbuf *t;
293	  if ((t = m_get()) == NULL) goto dropfrag;
294	  fp = mtod(t, struct ipq *);
295	  insque(&fp->ip_link, &ipq.ip_link);
296	  fp->ipq_ttl = IPFRAGTTL;
297	  fp->ipq_p = ip->ip_p;
298	  fp->ipq_id = ip->ip_id;
299	  fp->frag_link.next = fp->frag_link.prev = &fp->frag_link;
300	  fp->ipq_src = ip->ip_src;
301	  fp->ipq_dst = ip->ip_dst;
302	  q = (struct ipasfrag *)fp;
303	  goto insert;
304	}
305
306	/*
307	 * Find a segment which begins after this one does.
308	 */
309	for (q = fp->frag_link.next; q != (struct ipasfrag *)&fp->frag_link;
310            q = q->ipf_next)
311		if (q->ipf_off > ip->ip_off)
312			break;
313
314	/*
315	 * If there is a preceding segment, it may provide some of
316	 * our data already.  If so, drop the data from the incoming
317	 * segment.  If it provides all of our data, drop us.
318	 */
319	if (q->ipf_prev != &fp->frag_link) {
320        struct ipasfrag *pq = q->ipf_prev;
321		i = pq->ipf_off + pq->ipf_len - ip->ip_off;
322		if (i > 0) {
323			if (i >= ip->ip_len)
324				goto dropfrag;
325			m_adj(dtom(ip), i);
326			ip->ip_off += i;
327			ip->ip_len -= i;
328		}
329	}
330
331	/*
332	 * While we overlap succeeding segments trim them or,
333	 * if they are completely covered, dequeue them.
334	 */
335	while (q != (struct ipasfrag*)&fp->frag_link &&
336            ip->ip_off + ip->ip_len > q->ipf_off) {
337		i = (ip->ip_off + ip->ip_len) - q->ipf_off;
338		if (i < q->ipf_len) {
339			q->ipf_len -= i;
340			q->ipf_off += i;
341			m_adj(dtom(q), i);
342			break;
343		}
344		q = q->ipf_next;
345		m_freem(dtom(q->ipf_prev));
346		ip_deq(q->ipf_prev);
347	}
348
349insert:
350	/*
351	 * Stick new segment in its place;
352	 * check for complete reassembly.
353	 */
354	ip_enq(iptofrag(ip), q->ipf_prev);
355	next = 0;
356	for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link;
357            q = q->ipf_next) {
358		if (q->ipf_off != next)
359                        return NULL;
360		next += q->ipf_len;
361	}
362	if (((struct ipasfrag *)(q->ipf_prev))->ipf_tos & 1)
363                return NULL;
364
365	/*
366	 * Reassembly is complete; concatenate fragments.
367	 */
368    q = fp->frag_link.next;
369	m = dtom(q);
370
371	q = (struct ipasfrag *) q->ipf_next;
372	while (q != (struct ipasfrag*)&fp->frag_link) {
373	  struct mbuf *t = dtom(q);
374	  q = (struct ipasfrag *) q->ipf_next;
375	  m_cat(m, t);
376	}
377
378	/*
379	 * Create header for new ip packet by
380	 * modifying header of first packet;
381	 * dequeue and discard fragment reassembly header.
382	 * Make header visible.
383	 */
384	q = fp->frag_link.next;
385
386	/*
387	 * If the fragments concatenated to an mbuf that's
388	 * bigger than the total size of the fragment, then and
389	 * m_ext buffer was alloced. But fp->ipq_next points to
390	 * the old buffer (in the mbuf), so we must point ip
391	 * into the new buffer.
392	 */
393	if (m->m_flags & M_EXT) {
394	  int delta = (char *)q - m->m_dat;
395	  q = (struct ipasfrag *)(m->m_ext + delta);
396	}
397
398	/* DEBUG_ARG("ip = %lx", (long)ip);
399	 * ip=(struct ipasfrag *)m->m_data; */
400
401    ip = fragtoip(q);
402	ip->ip_len = next;
403	ip->ip_tos &= ~1;
404	ip->ip_src = fp->ipq_src;
405	ip->ip_dst = fp->ipq_dst;
406	remque(&fp->ip_link);
407	(void) m_free(dtom(fp));
408	m->m_len += (ip->ip_hl << 2);
409	m->m_data -= (ip->ip_hl << 2);
410
411	return ip;
412
413dropfrag:
414	STAT(ipstat.ips_fragdropped++);
415	m_freem(m);
416        return NULL;
417}
418
419/*
420 * Free a fragment reassembly header and all
421 * associated datagrams.
422 */
423static void
424ip_freef(struct ipq *fp)
425{
426	register struct ipasfrag *q, *p;
427
428	for (q = fp->frag_link.next; q != (struct ipasfrag*)&fp->frag_link; q = p) {
429		p = q->ipf_next;
430		ip_deq(q);
431		m_freem(dtom(q));
432	}
433	remque(&fp->ip_link);
434	(void) m_free(dtom(fp));
435}
436
437/*
438 * Put an ip fragment on a reassembly chain.
439 * Like insque, but pointers in middle of structure.
440 */
441static void
442ip_enq(register struct ipasfrag *p, register struct ipasfrag *prev)
443{
444	DEBUG_CALL("ip_enq");
445	DEBUG_ARG("prev = %lx", (long)prev);
446	p->ipf_prev =  prev;
447	p->ipf_next = prev->ipf_next;
448	((struct ipasfrag *)(prev->ipf_next))->ipf_prev = p;
449	prev->ipf_next = p;
450}
451
452/*
453 * To ip_enq as remque is to insque.
454 */
455static void
456ip_deq(register struct ipasfrag *p)
457{
458	((struct ipasfrag *)(p->ipf_prev))->ipf_next = p->ipf_next;
459	((struct ipasfrag *)(p->ipf_next))->ipf_prev = p->ipf_prev;
460}
461
462/*
463 * IP timer processing;
464 * if a timer expires on a reassembly
465 * queue, discard it.
466 */
467void
468ip_slowtimo(void)
469{
470    struct qlink *l;
471
472	DEBUG_CALL("ip_slowtimo");
473
474    l = ipq.ip_link.next;
475
476        if (l == NULL)
477	   return;
478
479	while (l != &ipq.ip_link) {
480        struct ipq *fp = container_of(l, struct ipq, ip_link);
481        l = l->next;
482		if (--fp->ipq_ttl == 0) {
483			STAT(ipstat.ips_fragtimeout++);
484			ip_freef(fp);
485		}
486	}
487}
488
489/*
490 * Do option processing on a datagram,
491 * possibly discarding it if bad options are encountered,
492 * or forwarding it if source-routed.
493 * Returns 1 if packet has been forwarded/freed,
494 * 0 if the packet should be processed further.
495 */
496
497#ifdef notdef
498
499int
500ip_dooptions(m)
501	struct mbuf *m;
502{
503	register struct ip *ip = mtod(m, struct ip *);
504	register u_char *cp;
505	register struct ip_timestamp *ipt;
506	register struct in_ifaddr *ia;
507/*	int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0; */
508	int opt, optlen, cnt, off, code, type, forward = 0;
509	struct in_addr *sin, dst;
510typedef u_int32_t n_time;
511	n_time ntime;
512
513	dst = ip->ip_dst;
514	cp = (u_char *)(ip + 1);
515	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
516	for (; cnt > 0; cnt -= optlen, cp += optlen) {
517		opt = cp[IPOPT_OPTVAL];
518		if (opt == IPOPT_EOL)
519			break;
520		if (opt == IPOPT_NOP)
521			optlen = 1;
522		else {
523			optlen = cp[IPOPT_OLEN];
524			if (optlen <= 0 || optlen > cnt) {
525				code = &cp[IPOPT_OLEN] - (u_char *)ip;
526				goto bad;
527			}
528		}
529		switch (opt) {
530
531		default:
532			break;
533
534		/*
535		 * Source routing with record.
536		 * Find interface with current destination address.
537		 * If none on this machine then drop if strictly routed,
538		 * or do nothing if loosely routed.
539		 * Record interface address and bring up next address
540		 * component.  If strictly routed make sure next
541		 * address is on directly accessible net.
542		 */
543		case IPOPT_LSRR:
544		case IPOPT_SSRR:
545			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
546				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
547				goto bad;
548			}
549			ipaddr.sin_addr = ip->ip_dst;
550			ia = (struct in_ifaddr *)
551				ifa_ifwithaddr((struct sockaddr *)&ipaddr);
552			if (ia == 0) {
553				if (opt == IPOPT_SSRR) {
554					type = ICMP_UNREACH;
555					code = ICMP_UNREACH_SRCFAIL;
556					goto bad;
557				}
558				/*
559				 * Loose routing, and not at next destination
560				 * yet; nothing to do except forward.
561				 */
562				break;
563			}
564			off--;			/ * 0 origin *  /
565			if (off > optlen - sizeof(struct in_addr)) {
566				/*
567				 * End of source route.  Should be for us.
568				 */
569				save_rte(cp, ip->ip_src);
570				break;
571			}
572			/*
573			 * locate outgoing interface
574			 */
575			bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
576			    sizeof(ipaddr.sin_addr));
577			if (opt == IPOPT_SSRR) {
578#define	INA	struct in_ifaddr *
579#define	SA	struct sockaddr *
580 			    if ((ia = (INA)ifa_ifwithdstaddr((SA)&ipaddr)) == 0)
581				ia = (INA)ifa_ifwithnet((SA)&ipaddr);
582			} else
583				ia = ip_rtaddr(ipaddr.sin_addr);
584			if (ia == 0) {
585				type = ICMP_UNREACH;
586				code = ICMP_UNREACH_SRCFAIL;
587				goto bad;
588			}
589			ip->ip_dst = ipaddr.sin_addr;
590			bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
591			    (caddr_t)(cp + off), sizeof(struct in_addr));
592			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
593			/*
594			 * Let ip_intr's mcast routing check handle mcast pkts
595			 */
596			forward = !IN_MULTICAST(ntohl(ip->ip_dst.s_addr));
597			break;
598
599		case IPOPT_RR:
600			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
601				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
602				goto bad;
603			}
604			/*
605			 * If no space remains, ignore.
606			 */
607			off--;			 * 0 origin *
608			if (off > optlen - sizeof(struct in_addr))
609				break;
610			bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
611			    sizeof(ipaddr.sin_addr));
612			/*
613			 * locate outgoing interface; if we're the destination,
614			 * use the incoming interface (should be same).
615			 */
616			if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
617			    (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
618				type = ICMP_UNREACH;
619				code = ICMP_UNREACH_HOST;
620				goto bad;
621			}
622			bcopy((caddr_t)&(IA_SIN(ia)->sin_addr),
623			    (caddr_t)(cp + off), sizeof(struct in_addr));
624			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
625			break;
626
627		case IPOPT_TS:
628			code = cp - (u_char *)ip;
629			ipt = (struct ip_timestamp *)cp;
630			if (ipt->ipt_len < 5)
631				goto bad;
632			if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
633				if (++ipt->ipt_oflw == 0)
634					goto bad;
635				break;
636			}
637			sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
638			switch (ipt->ipt_flg) {
639
640			case IPOPT_TS_TSONLY:
641				break;
642
643			case IPOPT_TS_TSANDADDR:
644				if (ipt->ipt_ptr + sizeof(n_time) +
645				    sizeof(struct in_addr) > ipt->ipt_len)
646					goto bad;
647				ipaddr.sin_addr = dst;
648				ia = (INA)ifaof_ i f p foraddr((SA)&ipaddr,
649							    m->m_pkthdr.rcvif);
650				if (ia == 0)
651					continue;
652				bcopy((caddr_t)&IA_SIN(ia)->sin_addr,
653				    (caddr_t)sin, sizeof(struct in_addr));
654				ipt->ipt_ptr += sizeof(struct in_addr);
655				break;
656
657			case IPOPT_TS_PRESPEC:
658				if (ipt->ipt_ptr + sizeof(n_time) +
659				    sizeof(struct in_addr) > ipt->ipt_len)
660					goto bad;
661				bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
662				    sizeof(struct in_addr));
663				if (ifa_ifwithaddr((SA)&ipaddr) == 0)
664					continue;
665				ipt->ipt_ptr += sizeof(struct in_addr);
666				break;
667
668			default:
669				goto bad;
670			}
671			ntime = iptime();
672			bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
673			    sizeof(n_time));
674			ipt->ipt_ptr += sizeof(n_time);
675		}
676	}
677	if (forward) {
678		ip_forward(m, 1);
679		return (1);
680	}
681		}
682	}
683	return (0);
684bad:
685	/* ip->ip_len -= ip->ip_hl << 2;   XXX icmp_error adds in hdr length */
686
687/* Not yet */
688 	icmp_error(m, type, code, 0, 0);
689
690	STAT(ipstat.ips_badoptions++);
691	return (1);
692}
693
694#endif /* notdef */
695
696/*
697 * Strip out IP options, at higher
698 * level protocol in the kernel.
699 * Second argument is buffer to which options
700 * will be moved, and return value is their length.
701 * (XXX) should be deleted; last arg currently ignored.
702 */
703void
704ip_stripoptions(register struct mbuf *m, struct mbuf *mopt)
705{
706	register int i;
707	struct ip *ip = mtod(m, struct ip *);
708	register caddr_t opts;
709	int olen;
710
711	olen = (ip->ip_hl<<2) - sizeof (struct ip);
712	opts = (caddr_t)(ip + 1);
713	i = m->m_len - (sizeof (struct ip) + olen);
714	memcpy(opts, opts  + olen, (unsigned)i);
715	m->m_len -= olen;
716
717	ip->ip_hl = sizeof(struct ip) >> 2;
718}
719