[apple/xnu.git] / bsd / netinet6 / ipcomp_input.c

/*	$KAME: ipcomp_input.c,v 1.11 2000/02/22 14:04:23 itojun Exp $	*/

/*
 * Copyright (C) 1999 WIDE Project.
 * 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. Neither the name of the project 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 PROJECT 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 PROJECT 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.
 */

/*
 * RFC2393 IP payload compression protocol (IPComp).
 */

#define _IP_VHL
#if (defined(__FreeBSD__) && __FreeBSD__ >= 3) || defined(__NetBSD__)
#include "opt_inet.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/syslog.h>

#include <net/if.h>
#include <net/route.h>
#include <net/netisr.h>
#include <net/zlib.h>
#include <kern/cpu_number.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/ip_ecn.h>

#if INET6
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#endif
#include <netinet6/ipcomp.h>

#include <netinet6/ipsec.h>
#include <netkey/key.h>
#include <netkey/keydb.h>
#include <netkey/key_debug.h>

#include <net/net_osdep.h>

#define IPLEN_FLIPPED


#if INET
extern struct protosw * ip_protox[];
#if defined(__bsdi__) || defined(__NetBSD__)
extern u_char ip_protox[];
#endif

void
ipcomp4_input(struct mbuf *m, int off)
{
	struct ip *ip;
	struct ipcomp *ipcomp;
	struct ipcomp_algorithm *algo;
	u_int16_t cpi;	/* host order */
	u_int16_t nxt;
	size_t hlen;
	int error;
	size_t newlen, olen;
	struct secasvar *sav = NULL;


	if (off + sizeof(struct ipcomp) > MHLEN) {
		/*XXX the restriction should be relaxed*/
		ipseclog((LOG_DEBUG, "IPv4 IPComp input: assumption failed "
		    "(header too long)\n"));
		ipsecstat.in_inval++;
		goto fail;
	}
	if (m->m_len < off + sizeof(struct ipcomp)) {
		m = m_pullup(m, off + sizeof(struct ipcomp));
		if (!m) {
			ipseclog((LOG_DEBUG, "IPv4 IPComp input: can't pullup;"
				"dropping the packet for simplicity\n"));
			ipsecstat.in_nomem++;
			goto fail;
		}
	} else if (m->m_len > off + sizeof(struct ipcomp)) {
		/* chop header part from the packet header chain */
		struct mbuf *n;
		MGETHDR(n, M_DONTWAIT, MT_HEADER);
		if (!n) {
			ipsecstat.in_nomem++;
			goto fail;
		}
		M_COPY_PKTHDR(n, m);
		MH_ALIGN(n, off + sizeof(struct ipcomp));
		n->m_len = off + sizeof(struct ipcomp);
		bcopy(mtod(m, caddr_t), mtod(n, caddr_t),
			off + sizeof(struct ipcomp));
		m_adj(m, off + sizeof(struct ipcomp));
		m->m_flags &= ~M_PKTHDR;
		n->m_next = m;
		m = n;
	}

	ip = mtod(m, struct ip *);
	ipcomp = (struct ipcomp *)(((caddr_t)ip) + off);
	nxt = ipcomp->comp_nxt;
#ifdef _IP_VHL
	hlen = IP_VHL_HL(ip->ip_vhl) << 2;
#else
	hlen = ip->ip_hl << 2;
#endif

	cpi = ntohs(ipcomp->comp_cpi);

	if (cpi >= IPCOMP_CPI_NEGOTIATE_MIN) {
		sav = key_allocsa(AF_INET, (caddr_t)&ip->ip_src,
			(caddr_t)&ip->ip_dst, IPPROTO_IPCOMP, htonl(cpi));
		if (sav != NULL
		 && (sav->state == SADB_SASTATE_MATURE
		  || sav->state == SADB_SASTATE_DYING)) {
			cpi = sav->alg_enc;	/*XXX*/
			/* other parameters to look at? */
		}
	}
	if (cpi < IPCOMP_MAX && ipcomp_algorithms[cpi].decompress != NULL)
		algo = &ipcomp_algorithms[cpi];
	else
		algo = NULL;
	if (!algo) {
		ipseclog((LOG_WARNING, "IPv4 IPComp input: unknown cpi %u\n",
			cpi));
		ipsecstat.in_nosa++;
		goto fail;
	}

	/* chop ipcomp header */
	ipcomp = NULL;
	m->m_len -= sizeof(struct ipcomp);
	m->m_pkthdr.len -= sizeof(struct ipcomp);
#ifdef IPLEN_FLIPPED
	ip->ip_len -= sizeof(struct ipcomp);
#else
	ip->ip_len = htons(ntohs(ip->ip_len) - sizeof(struct ipcomp));
#endif

	olen = m->m_pkthdr.len;
	newlen = m->m_pkthdr.len - off;
	error = (*algo->decompress)(m, m->m_next, &newlen);
	if (error != 0) {
		if (error == EINVAL)
			ipsecstat.in_inval++;
		else if (error == ENOBUFS)
			ipsecstat.in_nomem++;
		m = NULL;
		goto fail;
	}
	ipsecstat.in_comphist[cpi]++;

	/*
	 * returning decompressed packet onto icmp is meaningless.
	 * mark it decrypted to prevent icmp from attaching original packet.
	 */
	m->m_flags |= M_DECRYPTED;

	m->m_pkthdr.len = off + newlen;
	ip = mtod(m, struct ip *);
    {
	size_t len;
#ifdef IPLEN_FLIPPED
	len = ip->ip_len;
#else
	len = ntohs(ip->ip_len);
#endif
	/*
	 * be careful about underflow.  also, do not assign exact value
	 * as ip_len is manipulated differently on *BSDs.
	 */
	len += m->m_pkthdr.len;
	len -= olen;
	if (len & ~0xffff) {
		/* packet too big after decompress */
		ipsecstat.in_inval++;
		goto fail;
	}
#ifdef IPLEN_FLIPPED
	ip->ip_len = len & 0xffff;
#else
	ip->ip_len = htons(len & 0xffff);
#endif
	ip->ip_p = nxt;
    }

	if (sav) {
		key_sa_recordxfer(sav, m);
		key_freesav(sav);
		sav = NULL;
	}

	if (nxt != IPPROTO_DONE)
		(*ip_protox[nxt]->pr_input)(m, off);
	else
		m_freem(m);
	m = NULL;

	ipsecstat.in_success++;
	return;

fail:
	if (sav)
		key_freesav(sav);
	if (m)
		m_freem(m);
	return;
}
#endif /* INET */

#if INET6
int
ipcomp6_input(mp, offp)
	struct mbuf **mp;
	int *offp;
{
	struct mbuf *m, *md;
	int off;
	struct ip6_hdr *ip6;
	struct mbuf *ipcompm;
	struct ipcomp *ipcomp;
	struct ipcomp_algorithm *algo;
	u_int16_t cpi;	/* host order */
	u_int16_t nxt;
	int error;
	size_t newlen;
	struct secasvar *sav = NULL;

	m = *mp;
	off = *offp;

	IP6_EXTHDR_CHECK(m, off, sizeof(struct ipcomp), IPPROTO_DONE);

    {
	int skip;
	struct mbuf *n;
	struct mbuf *p, *q;
	size_t l;

	skip = off;
	for (n = m; n && skip > 0; n = n->m_next) {
		if (n->m_len <= skip) {
			skip -= n->m_len;
			continue;
		}
		break;
	}
	if (!n) {
		ipseclog((LOG_DEBUG, "IPv6 IPComp input: wrong mbuf chain\n"));
		ipsecstat.in_inval++;
		goto fail;
	}
	if (n->m_len < skip + sizeof(struct ipcomp)) {
		ipseclog((LOG_DEBUG, "IPv6 IPComp input: wrong mbuf chain\n"));
		ipsecstat.in_inval++;
		goto fail;
	}
	ip6 = mtod(m, struct ip6_hdr *);
	ipcompm = n;
	ipcomp = (struct ipcomp *)(mtod(n, caddr_t) + skip);
	if (n->m_len > skip + sizeof(struct ipcomp)) {
		/* split mbuf to ease the following steps*/
		l = n->m_len - (skip + sizeof(struct ipcomp));
		p = m_copym(n, skip + sizeof(struct ipcomp), l , M_DONTWAIT);
		if (!p) {
			ipsecstat.in_nomem++;
			goto fail;
		}
		for (q = p; q && q->m_next; q = q->m_next)
			;
		q->m_next = n->m_next;
		n->m_next = p;
		n->m_len -= l;
		md = p;
	} else
		md = n->m_next;
    }

	nxt = ipcomp->comp_nxt;
	cpi = ntohs(ipcomp->comp_cpi);

	if (cpi >= IPCOMP_CPI_NEGOTIATE_MIN) {
		sav = key_allocsa(AF_INET6, (caddr_t)&ip6->ip6_src,
			(caddr_t)&ip6->ip6_dst, IPPROTO_IPCOMP, htonl(cpi));
		if (sav != NULL
		 && (sav->state == SADB_SASTATE_MATURE
		  || sav->state == SADB_SASTATE_DYING)) {
			cpi = sav->alg_enc;	/*XXX*/
			/* other parameters to look at? */
		}
	}
	if (cpi < IPCOMP_MAX && ipcomp_algorithms[cpi].decompress != NULL)
		algo = &ipcomp_algorithms[cpi];
	else
		algo = NULL;
	if (!algo) {
		ipseclog((LOG_WARNING, "IPv6 IPComp input: unknown cpi %u; "
			"dropping the packet for simplicity\n", cpi));
		ipsec6stat.in_nosa++;
		goto fail;
	}

	newlen = m->m_pkthdr.len - off - sizeof(struct ipcomp);
	error = (*algo->decompress)(m, md, &newlen);
	if (error != 0) {
		if (error == EINVAL)
			ipsec6stat.in_inval++;
		else if (error == ENOBUFS)
			ipsec6stat.in_nomem++;
		m = NULL;
		goto fail;
	}
	ipsec6stat.in_comphist[cpi]++;
	m->m_pkthdr.len = off + sizeof(struct ipcomp) + newlen;

	/*
	 * returning decompressed packet onto icmp is meaningless.
	 * mark it decrypted to prevent icmp from attaching original packet.
	 */
	m->m_flags |= M_DECRYPTED;

    {
	char *prvnxtp;

	/* chop IPComp header */
	prvnxtp = ip6_get_prevhdr(m, off);
	*prvnxtp = nxt;
	ipcompm->m_len -= sizeof(struct ipcomp);
	ipcompm->m_pkthdr.len -= sizeof(struct ipcomp);

	/* adjust payload length */
	ip6 = mtod(m, struct ip6_hdr *);
	if (((m->m_pkthdr.len - sizeof(struct ip6_hdr)) & ~0xffff) != 0)
		ip6->ip6_plen = 0;	/*now a jumbogram*/
	else
		ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr));
    }

	if (sav) {
		key_sa_recordxfer(sav, m);
		key_freesav(sav);
		sav = NULL;
	}
	*offp = off;
	*mp = m;
	ipsec6stat.in_success++;
	return nxt;

fail:
	if (m)
		m_freem(m);
	if (sav)
		key_freesav(sav);
	return IPPROTO_DONE;
}
#endif /* INET6 */
Commit	Line	Data
1c79356b A	1	/* $KAME: ipcomp_input.c,v 1.11 2000/02/22 14:04:23 itojun Exp $ */
	2
	3	/*
	4	* Copyright (C) 1999 WIDE Project.
	5	* All rights reserved.
	6	*
	7	* Redistribution and use in source and binary forms, with or without
	8	* modification, are permitted provided that the following conditions
	9	* are met:
	10	* 1. Redistributions of source code must retain the above copyright
	11	* notice, this list of conditions and the following disclaimer.
	12	* 2. Redistributions in binary form must reproduce the above copyright
	13	* notice, this list of conditions and the following disclaimer in the
	14	* documentation and/or other materials provided with the distribution.
	15	* 3. Neither the name of the project nor the names of its contributors
	16	* may be used to endorse or promote products derived from this software
	17	* without specific prior written permission.
	18	*
	19	* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
	20	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	21	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	22	* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
	23	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	24	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	25	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	26	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	27	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	28	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	29	* SUCH DAMAGE.
	30	*/
	31
	32	/*
	33	* RFC2393 IP payload compression protocol (IPComp).
	34	*/
	35
	36	#define _IP_VHL
	37	#if (defined(__FreeBSD__) && __FreeBSD__ >= 3) \|\| defined(__NetBSD__)
	38	#include "opt_inet.h"
	39	#endif
	40
	41	#include <sys/param.h>
	42	#include <sys/systm.h>
	43	#include <sys/malloc.h>
	44	#include <sys/mbuf.h>
	45	#include <sys/domain.h>
	46	#include <sys/protosw.h>
	47	#include <sys/socket.h>
	48	#include <sys/errno.h>
	49	#include <sys/time.h>
	50	#include <sys/kernel.h>
	51	#include <sys/syslog.h>
	52
	53	#include <net/if.h>
	54	#include <net/route.h>
	55	#include <net/netisr.h>
	56	#include <net/zlib.h>
	57	#include <kern/cpu_number.h>
	58
	59	#include <netinet/in.h>
	60	#include <netinet/in_systm.h>
	61	#include <netinet/in_var.h>
	62	#include <netinet/ip.h>
	63	#include <netinet/ip_var.h>
	64	#include <netinet/ip_ecn.h>
65
66	#if INET6
67	#include <netinet/ip6.h>
68	#include <netinet6/ip6_var.h>
69	#endif
70	#include <netinet6/ipcomp.h>
71
72	#include <netinet6/ipsec.h>
73	#include <netkey/key.h>
74	#include <netkey/keydb.h>
75	#include <netkey/key_debug.h>
76
77	#include <net/net_osdep.h>
78
79	#define IPLEN_FLIPPED
80
81
82	#if INET
83	extern struct protosw * ip_protox[];
84	#if defined(__bsdi__) \|\| defined(__NetBSD__)
85	extern u_char ip_protox[];
86	#endif
87
88	void
89	ipcomp4_input(struct mbuf *m, int off)
90	{
91	struct ip *ip;
92	struct ipcomp *ipcomp;
93	struct ipcomp_algorithm *algo;
94	u_int16_t cpi; /* host order */
95	u_int16_t nxt;
96	size_t hlen;
97	int error;
98	size_t newlen, olen;
99	struct secasvar *sav = NULL;
100
101
102	if (off + sizeof(struct ipcomp) > MHLEN) {
103	/XXX the restriction should be relaxed/
104	ipseclog((LOG_DEBUG, "IPv4 IPComp input: assumption failed "
105	"(header too long)\n"));
106	ipsecstat.in_inval++;
107	goto fail;
108	}
109	if (m->m_len < off + sizeof(struct ipcomp)) {
110	m = m_pullup(m, off + sizeof(struct ipcomp));
111	if (!m) {
112	ipseclog((LOG_DEBUG, "IPv4 IPComp input: can't pullup;"
113	"dropping the packet for simplicity\n"));
114	ipsecstat.in_nomem++;
115	goto fail;
116	}
117	} else if (m->m_len > off + sizeof(struct ipcomp)) {
118	/* chop header part from the packet header chain */
119	struct mbuf *n;
120	MGETHDR(n, M_DONTWAIT, MT_HEADER);
121	if (!n) {
122	ipsecstat.in_nomem++;
123	goto fail;
124	}
125	M_COPY_PKTHDR(n, m);
126	MH_ALIGN(n, off + sizeof(struct ipcomp));
127	n->m_len = off + sizeof(struct ipcomp);
128	bcopy(mtod(m, caddr_t), mtod(n, caddr_t),
129	off + sizeof(struct ipcomp));
130	m_adj(m, off + sizeof(struct ipcomp));
131	m->m_flags &= ~M_PKTHDR;
132	n->m_next = m;
133	m = n;
134	}
135
136	ip = mtod(m, struct ip *);
137	ipcomp = (struct ipcomp *)(((caddr_t)ip) + off);
138	nxt = ipcomp->comp_nxt;
139	#ifdef _IP_VHL
140	hlen = IP_VHL_HL(ip->ip_vhl) << 2;
141	#else
142	hlen = ip->ip_hl << 2;
143	#endif
144
145	cpi = ntohs(ipcomp->comp_cpi);
146
147	if (cpi >= IPCOMP_CPI_NEGOTIATE_MIN) {
148	sav = key_allocsa(AF_INET, (caddr_t)&ip->ip_src,
149	(caddr_t)&ip->ip_dst, IPPROTO_IPCOMP, htonl(cpi));
150	if (sav != NULL
151	&& (sav->state == SADB_SASTATE_MATURE
152	\|\| sav->state == SADB_SASTATE_DYING)) {
153	cpi = sav->alg_enc; /XXX/
154	/* other parameters to look at? */
155	}
156	}
157	if (cpi < IPCOMP_MAX && ipcomp_algorithms[cpi].decompress != NULL)
158	algo = &ipcomp_algorithms[cpi];
159	else
160	algo = NULL;
161	if (!algo) {
162	ipseclog((LOG_WARNING, "IPv4 IPComp input: unknown cpi %u\n",
163	cpi));
164	ipsecstat.in_nosa++;
165	goto fail;
166	}
167
168	/* chop ipcomp header */
169	ipcomp = NULL;
170	m->m_len -= sizeof(struct ipcomp);
171	m->m_pkthdr.len -= sizeof(struct ipcomp);
172	#ifdef IPLEN_FLIPPED
173	ip->ip_len -= sizeof(struct ipcomp);
174	#else
175	ip->ip_len = htons(ntohs(ip->ip_len) - sizeof(struct ipcomp));
176	#endif
177
178	olen = m->m_pkthdr.len;
179	newlen = m->m_pkthdr.len - off;
180	error = (*algo->decompress)(m, m->m_next, &newlen);
181	if (error != 0) {
182	if (error == EINVAL)
183	ipsecstat.in_inval++;
184	else if (error == ENOBUFS)
185	ipsecstat.in_nomem++;
186	m = NULL;
187	goto fail;
188	}
189	ipsecstat.in_comphist[cpi]++;
190
191	/*
192	* returning decompressed packet onto icmp is meaningless.
193	* mark it decrypted to prevent icmp from attaching original packet.
194	*/
195	m->m_flags \|= M_DECRYPTED;
196
197	m->m_pkthdr.len = off + newlen;
198	ip = mtod(m, struct ip *);
199	{
200	size_t len;
201	#ifdef IPLEN_FLIPPED
202	len = ip->ip_len;
203	#else
204	len = ntohs(ip->ip_len);
205	#endif
206	/*
207	* be careful about underflow. also, do not assign exact value
208	* as ip_len is manipulated differently on *BSDs.
209	*/
210	len += m->m_pkthdr.len;
211	len -= olen;
212	if (len & ~0xffff) {
213	/* packet too big after decompress */
214	ipsecstat.in_inval++;
215	goto fail;
216	}
217	#ifdef IPLEN_FLIPPED
218	ip->ip_len = len & 0xffff;
219	#else
220	ip->ip_len = htons(len & 0xffff);
221	#endif
222	ip->ip_p = nxt;
223	}
224
225	if (sav) {
226	key_sa_recordxfer(sav, m);
227	key_freesav(sav);
228	sav = NULL;
229	}
230
231	if (nxt != IPPROTO_DONE)
232	(*ip_protox[nxt]->pr_input)(m, off);
233	else
234	m_freem(m);
235	m = NULL;
236
237	ipsecstat.in_success++;
238	return;
239
240	fail:
241	if (sav)
242	key_freesav(sav);
243	if (m)
244	m_freem(m);
245	return;
246	}
247	#endif /* INET */
248
249	#if INET6
250	int
251	ipcomp6_input(mp, offp)
252	struct mbuf **mp;
253	int *offp;
254	{
255	struct mbuf m, md;
256	int off;
257	struct ip6_hdr *ip6;
258	struct mbuf *ipcompm;
259	struct ipcomp *ipcomp;
260	struct ipcomp_algorithm *algo;
261	u_int16_t cpi; /* host order */
262	u_int16_t nxt;
263	int error;
264	size_t newlen;
265	struct secasvar *sav = NULL;
266
267	m = *mp;
268	off = *offp;
269
270	IP6_EXTHDR_CHECK(m, off, sizeof(struct ipcomp), IPPROTO_DONE);
271
272	{
273	int skip;
274	struct mbuf *n;
275	struct mbuf p, q;
276	size_t l;
277
278	skip = off;
279	for (n = m; n && skip > 0; n = n->m_next) {
280	if (n->m_len <= skip) {
281	skip -= n->m_len;
282	continue;
283	}
284	break;
285	}
286	if (!n) {
287	ipseclog((LOG_DEBUG, "IPv6 IPComp input: wrong mbuf chain\n"));
288	ipsecstat.in_inval++;
289	goto fail;
290	}
291	if (n->m_len < skip + sizeof(struct ipcomp)) {
292	ipseclog((LOG_DEBUG, "IPv6 IPComp input: wrong mbuf chain\n"));
293	ipsecstat.in_inval++;
294	goto fail;
295	}
296	ip6 = mtod(m, struct ip6_hdr *);
297	ipcompm = n;
298	ipcomp = (struct ipcomp *)(mtod(n, caddr_t) + skip);
299	if (n->m_len > skip + sizeof(struct ipcomp)) {
300	/* split mbuf to ease the following steps*/
301	l = n->m_len - (skip + sizeof(struct ipcomp));
302	p = m_copym(n, skip + sizeof(struct ipcomp), l , M_DONTWAIT);
303	if (!p) {
304	ipsecstat.in_nomem++;
305	goto fail;
306	}
307	for (q = p; q && q->m_next; q = q->m_next)
308	;
309	q->m_next = n->m_next;
310	n->m_next = p;
311	n->m_len -= l;
312	md = p;
313	} else
314	md = n->m_next;
315	}
316
317	nxt = ipcomp->comp_nxt;
318	cpi = ntohs(ipcomp->comp_cpi);
319
320	if (cpi >= IPCOMP_CPI_NEGOTIATE_MIN) {
321	sav = key_allocsa(AF_INET6, (caddr_t)&ip6->ip6_src,
322	(caddr_t)&ip6->ip6_dst, IPPROTO_IPCOMP, htonl(cpi));
323	if (sav != NULL
324	&& (sav->state == SADB_SASTATE_MATURE
325	\|\| sav->state == SADB_SASTATE_DYING)) {
326	cpi = sav->alg_enc; /XXX/
327	/* other parameters to look at? */
328	}
329	}
330	if (cpi < IPCOMP_MAX && ipcomp_algorithms[cpi].decompress != NULL)
331	algo = &ipcomp_algorithms[cpi];
332	else
333	algo = NULL;
334	if (!algo) {
335	ipseclog((LOG_WARNING, "IPv6 IPComp input: unknown cpi %u; "
336	"dropping the packet for simplicity\n", cpi));
337	ipsec6stat.in_nosa++;
338	goto fail;
339	}
340
341	newlen = m->m_pkthdr.len - off - sizeof(struct ipcomp);
342	error = (*algo->decompress)(m, md, &newlen);
343	if (error != 0) {
344	if (error == EINVAL)
345	ipsec6stat.in_inval++;
346	else if (error == ENOBUFS)
347	ipsec6stat.in_nomem++;
348	m = NULL;
349	goto fail;
350	}
351	ipsec6stat.in_comphist[cpi]++;
352	m->m_pkthdr.len = off + sizeof(struct ipcomp) + newlen;
353
354	/*
355	* returning decompressed packet onto icmp is meaningless.
356	* mark it decrypted to prevent icmp from attaching original packet.
357	*/
358	m->m_flags \|= M_DECRYPTED;
359
360	{
361	char *prvnxtp;
362
363	/* chop IPComp header */
364	prvnxtp = ip6_get_prevhdr(m, off);
365	*prvnxtp = nxt;
366	ipcompm->m_len -= sizeof(struct ipcomp);
367	ipcompm->m_pkthdr.len -= sizeof(struct ipcomp);
368
369	/* adjust payload length */
370	ip6 = mtod(m, struct ip6_hdr *);
371	if (((m->m_pkthdr.len - sizeof(struct ip6_hdr)) & ~0xffff) != 0)
372	ip6->ip6_plen = 0; /now a jumbogram/
373	else
374	ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(struct ip6_hdr));
375	}
376
377	if (sav) {
378	key_sa_recordxfer(sav, m);
379	key_freesav(sav);
380	sav = NULL;
381	}
382	*offp = off;
383	*mp = m;
384	ipsec6stat.in_success++;
385	return nxt;
386
387	fail:
388	if (m)
389	m_freem(m);
390	if (sav)
391	key_freesav(sav);
392	return IPPROTO_DONE;
393	}
394	#endif /* INET6 */