[apple/xnu.git] / bsd / kern / uipc_mbuf2.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*	$NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej 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.
 */

/*
 * Copyright (c) 1982, 1986, 1988, 1991, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)uipc_mbuf.c	8.4 (Berkeley) 2/14/95
 */


/*#define PULLDOWN_DEBUG*/

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#if defined(PULLDOWN_STAT) && defined(INET6)
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#endif

/*
 * ensure that [off, off + len) is contiguous on the mbuf chain "m".
 * packet chain before "off" is kept untouched.
 * if offp == NULL, the target will start at <retval, 0> on resulting chain.
 * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
 *
 * on error return (NULL return value), original "m" will be freed.
 *
 * XXX M_TRAILINGSPACE/M_LEADINGSPACE on shared cluster (sharedcluster)
 */
struct mbuf *
m_pulldown(m, off, len, offp)
	struct mbuf *m;
	int off, len;
	int *offp;
{
	struct mbuf *n, *o;
	int hlen, tlen, olen;
	int sharedcluster;
#if defined(PULLDOWN_STAT) && defined(INET6)
	static struct mbuf *prev = NULL;
	int prevlen = 0, prevmlen = 0;
#endif

	/* check invalid arguments. */
	if (m == NULL)
		panic("m == NULL in m_pulldown()");
	if (len > MCLBYTES) {
		m_freem(m);
		return NULL;	/* impossible */
	}

#if defined(PULLDOWN_STAT) && defined(INET6)
	ip6stat.ip6s_pulldown++;
#endif

#if defined(PULLDOWN_STAT) && defined(INET6)
	/* statistics for m_pullup */
	ip6stat.ip6s_pullup++;
	if (off + len > MHLEN)
		ip6stat.ip6s_pullup_fail++;
	else {
		int dlen, mlen;

		dlen = (prev == m) ? prevlen : m->m_len;
		mlen = (prev == m) ? prevmlen : m->m_len + M_TRAILINGSPACE(m);

		if (dlen >= off + len)
			ip6stat.ip6s_pullup--; /* call will not be made! */
		else if ((m->m_flags & M_EXT) != 0) {
			ip6stat.ip6s_pullup_alloc++;
			ip6stat.ip6s_pullup_copy++;
		} else {
			if (mlen >= off + len)
				ip6stat.ip6s_pullup_copy++;
			else {
				ip6stat.ip6s_pullup_alloc++;
				ip6stat.ip6s_pullup_copy++;
			}
		}

		prevlen = off + len;
		prevmlen = MHLEN;
	}

	/* statistics for m_pullup2 */
	ip6stat.ip6s_pullup2++;
	if (off + len > MCLBYTES)
		ip6stat.ip6s_pullup2_fail++;
	else {
		int dlen, mlen;

		dlen = (prev == m) ? prevlen : m->m_len;
		mlen = (prev == m) ? prevmlen : m->m_len + M_TRAILINGSPACE(m);
		prevlen = off + len;
		prevmlen = mlen;

		if (dlen >= off + len)
			ip6stat.ip6s_pullup2--; /* call will not be made! */
		else if ((m->m_flags & M_EXT) != 0) {
			ip6stat.ip6s_pullup2_alloc++;
			ip6stat.ip6s_pullup2_copy++;
			prevmlen = (off + len > MHLEN) ? MCLBYTES : MHLEN;
		} else {
			if (mlen >= off + len)
				ip6stat.ip6s_pullup2_copy++;
			else {
				ip6stat.ip6s_pullup2_alloc++;
				ip6stat.ip6s_pullup2_copy++;
				prevmlen = (off + len > MHLEN) ? MCLBYTES
							       : MHLEN;
			}
		}
	}

	prev = m;
#endif

#ifdef PULLDOWN_DEBUG
    {
	struct mbuf *t;
	printf("before:");
	for (t = m; t; t = t->m_next)
		printf(" %d", t->m_len);
	printf("\n");
    }
#endif
	n = m;
	while (n != NULL && off > 0) {
		if (n->m_len > off)
			break;
		off -= n->m_len;
		n = n->m_next;
	}
	/* be sure to point non-empty mbuf */
	while (n != NULL && n->m_len == 0)
		n = n->m_next;
	if (!n) {
		m_freem(m);
		return NULL;	/* mbuf chain too short */
	}

	/*
	 * the target data is on <n, off>.
	 * if we got enough data on the mbuf "n", we're done.
	 */
	if ((off == 0 || offp) && len <= n->m_len - off)
		goto ok;

#if defined(PULLDOWN_STAT) && defined(INET6)
	ip6stat.ip6s_pulldown_copy++;
#endif

	/*
	 * when len < n->m_len - off and off != 0, it is a special case.
	 * len bytes from <n, off> sits in single mbuf, but the caller does
	 * not like the starting position (off).
	 * chop the current mbuf into two pieces, set off to 0.
	 */
	if (len < n->m_len - off) {
		o = m_copym(n, off, n->m_len - off, M_DONTWAIT);
		if (o == NULL) {
			m_freem(m);
			return NULL;	/* ENOBUFS */
		}
		n->m_len = off;
		o->m_next = n->m_next;
		n->m_next = o;
		n = n->m_next;
		off = 0;
		goto ok;
	}

	/*
	 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
	 * and construct contiguous mbuf with m_len == len.
	 * note that hlen + tlen == len, and tlen > 0.
	 */
	hlen = n->m_len - off;
	tlen = len - hlen;

	/*
	 * ensure that we have enough trailing data on mbuf chain.
	 * if not, we can do nothing about the chain.
	 */
	olen = 0;
	for (o = n->m_next; o != NULL; o = o->m_next)
		olen += o->m_len;
	if (hlen + olen < len) {
		m_freem(m);
		return NULL;	/* mbuf chain too short */
	}

	/*
	 * easy cases first.
	 * we need to use m_copydata() to get data from <n->m_next, 0>.
	 */
	if ((n->m_flags & M_EXT) == 0)
		sharedcluster = 0;
	else {
#ifdef __bsdi__
		if (n->m_ext.ext_func)
#else
		if (n->m_ext.ext_free)
#endif
			sharedcluster = 1;
#ifdef __NetBSD__
		else if (MCLISREFERENCED(n))
#else
		else if (mclrefcnt[mtocl(n->m_ext.ext_buf)] > 1)
#endif
			sharedcluster = 1;
		else
			sharedcluster = 0;
	}
	if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen
	 && !sharedcluster) {
		m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
		n->m_len += tlen;
		m_adj(n->m_next, tlen);
		goto ok;
	}
	if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen
	 && !sharedcluster) {
		n->m_next->m_data -= hlen;
		n->m_next->m_len += hlen;
		bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
		n->m_len -= hlen;
		n = n->m_next;
		off = 0;
		goto ok;
	}

	/*
	 * now, we need to do the hard way.  don't m_copy as there's no room
	 * on both end.
	 */
#if defined(PULLDOWN_STAT) && defined(INET6)
	ip6stat.ip6s_pulldown_alloc++;
#endif
	MGET(o, M_DONTWAIT, m->m_type);
	if (o == NULL) {
		m_freem(m);
		return NULL;	/* ENOBUFS */
	}
	if (len > MHLEN) {	/* use MHLEN just for safety */
		MCLGET(o, M_DONTWAIT);
		if ((o->m_flags & M_EXT) == 0) {
			m_freem(m);
			m_free(o);
			return NULL;	/* ENOBUFS */
		}
	}
	/* get hlen from <n, off> into <o, 0> */
	o->m_len = hlen;
	bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
	n->m_len -= hlen;
	/* get tlen from <n->m_next, 0> into <o, hlen> */
	m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
	o->m_len += tlen;
	m_adj(n->m_next, tlen);
	o->m_next = n->m_next;
	n->m_next = o;
	n = o;
	off = 0;

ok:
#ifdef PULLDOWN_DEBUG
    {
	struct mbuf *t;
	printf("after:");
	for (t = m; t; t = t->m_next)
		printf("%c%d", t == n ? '*' : ' ', t->m_len);
	printf(" (off=%d)\n", off);
    }
#endif
	if (offp)
		*offp = off;
	return n;
}

/*
 * pkthdr.aux chain manipulation.
 * we don't allow clusters at this moment. 
 */
struct mbuf *
m_aux_add(m, af, type)
	struct mbuf *m;
	int af, type;
{
	struct mbuf *n;
	struct mauxtag *t;

	if ((m->m_flags & M_PKTHDR) == 0)
		return NULL;

	n = m_aux_find(m, af, type);
	if (n)
		return n;

	MGET(n, M_WAIT, m->m_type);
	if (n == NULL)
		return NULL;

	t = mtod(n, struct mauxtag *);
	t->af = af;
	t->type = type;
	n->m_data += sizeof(struct mauxtag);
	n->m_len = 0;
	n->m_next = m->m_pkthdr.aux;
	m->m_pkthdr.aux = n;
	return n;
}

struct mbuf *
m_aux_find(m, af, type)
	struct mbuf *m;
	int af, type;
{
	struct mbuf *n;
	struct mauxtag *t;

	if ((m->m_flags & M_PKTHDR) == 0)
		return NULL;

	for (n = m->m_pkthdr.aux; n; n = n->m_next) {
		t = (struct mauxtag *)n->m_dat;
		if (t->af == af && t->type == type)
			return n;
	}
	return NULL;
}

void
m_aux_delete(m, victim)
	struct mbuf *m;
	struct mbuf *victim;
{
	struct mbuf *n, *prev, *next;
	struct mauxtag *t;

	if ((m->m_flags & M_PKTHDR) == 0)
		return;

	prev = NULL;
	n = m->m_pkthdr.aux;
	while (n) {
		t = (struct mauxtag *)n->m_dat;
		next = n->m_next;
		if (n == victim) {
			if (prev)
				prev->m_next = n->m_next;
			else
				m->m_pkthdr.aux = n->m_next;
			n->m_next = NULL;
			m_free(n);
		} else
			prev = n;
		n = next;
	}
}
Commit	Line	Data
1c79356b A	1	/*
	2	* Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
	6	* The contents of this file constitute Original Code as defined in and
	7	* are subject to the Apple Public Source License Version 1.1 (the
	8	* "License"). You may not use this file except in compliance with the
	9	* License. Please obtain a copy of the License at
	10	* http://www.apple.com/publicsource and read it before using this file.
	11	*
	12	* This Original Code and all software distributed under the License are
	13	* distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	14	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	15	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	16	* FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
	17	* License for the specific language governing rights and limitations
	18	* under the License.
	19	*
	20	* @APPLE_LICENSE_HEADER_END@
	21	*/
	22	/* $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $ */
	23
	24	/*
	25	* Copyright (C) 1999 WIDE Project.
	26	* All rights reserved.
	27	*
	28	* Redistribution and use in source and binary forms, with or without
	29	* modification, are permitted provided that the following conditions
	30	* are met:
	31	* 1. Redistributions of source code must retain the above copyright
	32	* notice, this list of conditions and the following disclaimer.
	33	* 2. Redistributions in binary form must reproduce the above copyright
	34	* notice, this list of conditions and the following disclaimer in the
	35	* documentation and/or other materials provided with the distribution.
	36	* 3. Neither the name of the project nor the names of its contributors
	37	* may be used to endorse or promote products derived from this software
	38	* without specific prior written permission.
	39	*
	40	* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
	41	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	42	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	43	* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
	44	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	45	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	46	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	47	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	48	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	49	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	50	* SUCH DAMAGE.
	51	*/
	52
	53	/*
	54	* Copyright (c) 1982, 1986, 1988, 1991, 1993
	55	* The Regents of the University of California. All rights reserved.
	56	*
	57	* Redistribution and use in source and binary forms, with or without
	58	* modification, are permitted provided that the following conditions
	59	* are met:
	60	* 1. Redistributions of source code must retain the above copyright
	61	* notice, this list of conditions and the following disclaimer.
	62	* 2. Redistributions in binary form must reproduce the above copyright
	63	* notice, this list of conditions and the following disclaimer in the
	64	* documentation and/or other materials provided with the distribution.
65	* 3. All advertising materials mentioning features or use of this software
66	* must display the following acknowledgement:
67	* This product includes software developed by the University of
68	* California, Berkeley and its contributors.
69	* 4. Neither the name of the University nor the names of its contributors
70	* may be used to endorse or promote products derived from this software
71	* without specific prior written permission.
72	*
73	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
74	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
75	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
76	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
77	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
78	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
79	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
80	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
81	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
82	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
83	* SUCH DAMAGE.
84	*
85	* @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
86	*/
87
1c79356b	88
9bccf70c	89	/#define PULLDOWN_DEBUG/
1c79356b A	90
	91	#include <sys/param.h>
	92	#include <sys/systm.h>
	93	#include <sys/proc.h>
	94	#include <sys/malloc.h>
	95	#include <sys/mbuf.h>
	96	#if defined(PULLDOWN_STAT) && defined(INET6)
	97	#include <netinet/in.h>
	98	#include <netinet/ip6.h>
	99	#include <netinet6/ip6_var.h>
	100	#endif
	101
	102	/*
	103	* ensure that [off, off + len) is contiguous on the mbuf chain "m".
	104	* packet chain before "off" is kept untouched.
	105	* if offp == NULL, the target will start at <retval, 0> on resulting chain.
	106	* if offp != NULL, the target will start at <retval, *offp> on resulting chain.
	107	*
	108	* on error return (NULL return value), original "m" will be freed.
	109	*
	110	* XXX M_TRAILINGSPACE/M_LEADINGSPACE on shared cluster (sharedcluster)
	111	*/
	112	struct mbuf *
	113	m_pulldown(m, off, len, offp)
	114	struct mbuf *m;
	115	int off, len;
	116	int *offp;
	117	{
	118	struct mbuf n, o;
	119	int hlen, tlen, olen;
	120	int sharedcluster;
	121	#if defined(PULLDOWN_STAT) && defined(INET6)
	122	static struct mbuf *prev = NULL;
	123	int prevlen = 0, prevmlen = 0;
	124	#endif
	125
	126	/* check invalid arguments. */
	127	if (m == NULL)
	128	panic("m == NULL in m_pulldown()");
	129	if (len > MCLBYTES) {
	130	m_freem(m);
	131	return NULL; /* impossible */
	132	}
	133
	134	#if defined(PULLDOWN_STAT) && defined(INET6)
	135	ip6stat.ip6s_pulldown++;
	136	#endif
	137
	138	#if defined(PULLDOWN_STAT) && defined(INET6)
	139	/* statistics for m_pullup */
	140	ip6stat.ip6s_pullup++;
	141	if (off + len > MHLEN)
	142	ip6stat.ip6s_pullup_fail++;
	143	else {
	144	int dlen, mlen;
	145
	146	dlen = (prev == m) ? prevlen : m->m_len;
	147	mlen = (prev == m) ? prevmlen : m->m_len + M_TRAILINGSPACE(m);
	148
	149	if (dlen >= off + len)
	150	ip6stat.ip6s_pullup--; /* call will not be made! */
	151	else if ((m->m_flags & M_EXT) != 0) {
	152	ip6stat.ip6s_pullup_alloc++;
	153	ip6stat.ip6s_pullup_copy++;
154	} else {
155	if (mlen >= off + len)
156	ip6stat.ip6s_pullup_copy++;
157	else {
158	ip6stat.ip6s_pullup_alloc++;
159	ip6stat.ip6s_pullup_copy++;
160	}
161	}
162
163	prevlen = off + len;
164	prevmlen = MHLEN;
165	}
166
167	/* statistics for m_pullup2 */
168	ip6stat.ip6s_pullup2++;
169	if (off + len > MCLBYTES)
170	ip6stat.ip6s_pullup2_fail++;
171	else {
172	int dlen, mlen;
173
174	dlen = (prev == m) ? prevlen : m->m_len;
175	mlen = (prev == m) ? prevmlen : m->m_len + M_TRAILINGSPACE(m);
176	prevlen = off + len;
177	prevmlen = mlen;
178
179	if (dlen >= off + len)
180	ip6stat.ip6s_pullup2--; /* call will not be made! */
181	else if ((m->m_flags & M_EXT) != 0) {
182	ip6stat.ip6s_pullup2_alloc++;
183	ip6stat.ip6s_pullup2_copy++;
184	prevmlen = (off + len > MHLEN) ? MCLBYTES : MHLEN;
185	} else {
186	if (mlen >= off + len)
187	ip6stat.ip6s_pullup2_copy++;
188	else {
189	ip6stat.ip6s_pullup2_alloc++;
190	ip6stat.ip6s_pullup2_copy++;
191	prevmlen = (off + len > MHLEN) ? MCLBYTES
192	: MHLEN;
193	}
194	}
195	}
196
197	prev = m;
198	#endif
199
200	#ifdef PULLDOWN_DEBUG
201	{
202	struct mbuf *t;
203	printf("before:");
204	for (t = m; t; t = t->m_next)
205	printf(" %d", t->m_len);
206	printf("\n");
207	}
208	#endif
209	n = m;
210	while (n != NULL && off > 0) {
211	if (n->m_len > off)
212	break;
213	off -= n->m_len;
214	n = n->m_next;
215	}
216	/* be sure to point non-empty mbuf */
217	while (n != NULL && n->m_len == 0)
218	n = n->m_next;
219	if (!n) {
220	m_freem(m);
221	return NULL; /* mbuf chain too short */
222	}
223
224	/*
225	* the target data is on <n, off>.
226	* if we got enough data on the mbuf "n", we're done.
227	*/
228	if ((off == 0 \|\| offp) && len <= n->m_len - off)
229	goto ok;
230
231	#if defined(PULLDOWN_STAT) && defined(INET6)
232	ip6stat.ip6s_pulldown_copy++;
233	#endif
234
235	/*
236	* when len < n->m_len - off and off != 0, it is a special case.
237	* len bytes from <n, off> sits in single mbuf, but the caller does
238	* not like the starting position (off).
239	* chop the current mbuf into two pieces, set off to 0.
240	*/
241	if (len < n->m_len - off) {
242	o = m_copym(n, off, n->m_len - off, M_DONTWAIT);
243	if (o == NULL) {
244	m_freem(m);
245	return NULL; /* ENOBUFS */
246	}
247	n->m_len = off;
248	o->m_next = n->m_next;
249	n->m_next = o;
250	n = n->m_next;
251	off = 0;
252	goto ok;
253	}
254
255	/*
256	* we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
257	* and construct contiguous mbuf with m_len == len.
258	* note that hlen + tlen == len, and tlen > 0.
259	*/
260	hlen = n->m_len - off;
261	tlen = len - hlen;
262
263	/*
264	* ensure that we have enough trailing data on mbuf chain.
265	* if not, we can do nothing about the chain.
266	*/
267	olen = 0;
268	for (o = n->m_next; o != NULL; o = o->m_next)
269	olen += o->m_len;
270	if (hlen + olen < len) {
271	m_freem(m);
272	return NULL; /* mbuf chain too short */
273	}
274
275	/*
276	* easy cases first.
277	* we need to use m_copydata() to get data from <n->m_next, 0>.
278	*/
279	if ((n->m_flags & M_EXT) == 0)
280	sharedcluster = 0;
281	else {
282	#ifdef __bsdi__
283	if (n->m_ext.ext_func)
284	#else
285	if (n->m_ext.ext_free)
286	#endif
287	sharedcluster = 1;
288	#ifdef __NetBSD__
289	else if (MCLISREFERENCED(n))
290	#else
291	else if (mclrefcnt[mtocl(n->m_ext.ext_buf)] > 1)
292	#endif
293	sharedcluster = 1;
294	else
295	sharedcluster = 0;
296	}
297	if ((off == 0 \|\| offp) && M_TRAILINGSPACE(n) >= tlen
298	&& !sharedcluster) {
299	m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
300	n->m_len += tlen;
301	m_adj(n->m_next, tlen);
302	goto ok;
303	}
304	if ((off == 0 \|\| offp) && M_LEADINGSPACE(n->m_next) >= hlen
305	&& !sharedcluster) {
306	n->m_next->m_data -= hlen;
307	n->m_next->m_len += hlen;
308	bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
309	n->m_len -= hlen;
310	n = n->m_next;
311	off = 0;
312	goto ok;
313	}
314
315	/*
316	* now, we need to do the hard way. don't m_copy as there's no room
317	* on both end.
318	*/
319	#if defined(PULLDOWN_STAT) && defined(INET6)
320	ip6stat.ip6s_pulldown_alloc++;
321	#endif
322	MGET(o, M_DONTWAIT, m->m_type);
323	if (o == NULL) {
324	m_freem(m);
325	return NULL; /* ENOBUFS */
326	}
327	if (len > MHLEN) { /* use MHLEN just for safety */
328	MCLGET(o, M_DONTWAIT);
329	if ((o->m_flags & M_EXT) == 0) {
330	m_freem(m);
331	m_free(o);
332	return NULL; /* ENOBUFS */
333	}
334	}
335	/* get hlen from <n, off> into <o, 0> */
336	o->m_len = hlen;
337	bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
338	n->m_len -= hlen;
339	/* get tlen from <n->m_next, 0> into <o, hlen> */
340	m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
341	o->m_len += tlen;
342	m_adj(n->m_next, tlen);
343	o->m_next = n->m_next;
344	n->m_next = o;
345	n = o;
346	off = 0;
347
348	ok:
349	#ifdef PULLDOWN_DEBUG
350	{
351	struct mbuf *t;
352	printf("after:");
353	for (t = m; t; t = t->m_next)
354	printf("%c%d", t == n ? '*' : ' ', t->m_len);
355	printf(" (off=%d)\n", off);
356	}
357	#endif
358	if (offp)
359	*offp = off;
360	return n;
361	}
362
363	/*
364	* pkthdr.aux chain manipulation.
365	* we don't allow clusters at this moment.
366	*/
367	struct mbuf *
368	m_aux_add(m, af, type)
369	struct mbuf *m;
370	int af, type;
371	{
372	struct mbuf *n;
373	struct mauxtag *t;
374
375	if ((m->m_flags & M_PKTHDR) == 0)
376	return NULL;
377
378	n = m_aux_find(m, af, type);
379	if (n)
380	return n;
381
0b4e3aa0	382	MGET(n, M_WAIT, m->m_type);
1c79356b A	383	if (n == NULL)
	384	return NULL;
	385
	386	t = mtod(n, struct mauxtag *);
	387	t->af = af;
	388	t->type = type;
	389	n->m_data += sizeof(struct mauxtag);
	390	n->m_len = 0;
	391	n->m_next = m->m_pkthdr.aux;
	392	m->m_pkthdr.aux = n;
	393	return n;
	394	}
	395
	396	struct mbuf *
	397	m_aux_find(m, af, type)
	398	struct mbuf *m;
	399	int af, type;
	400	{
	401	struct mbuf *n;
	402	struct mauxtag *t;
	403
	404	if ((m->m_flags & M_PKTHDR) == 0)
	405	return NULL;
	406
	407	for (n = m->m_pkthdr.aux; n; n = n->m_next) {
	408	t = (struct mauxtag *)n->m_dat;
	409	if (t->af == af && t->type == type)
	410	return n;
	411	}
	412	return NULL;
	413	}
	414
	415	void
	416	m_aux_delete(m, victim)
	417	struct mbuf *m;
	418	struct mbuf *victim;
	419	{
	420	struct mbuf n, prev, *next;
	421	struct mauxtag *t;
	422
	423	if ((m->m_flags & M_PKTHDR) == 0)
	424	return;
	425
	426	prev = NULL;
	427	n = m->m_pkthdr.aux;
	428	while (n) {
	429	t = (struct mauxtag *)n->m_dat;
	430	next = n->m_next;
	431	if (n == victim) {
	432	if (prev)
	433	prev->m_next = n->m_next;
	434	else
	435	m->m_pkthdr.aux = n->m_next;
	436	n->m_next = NULL;
	437	m_free(n);
	438	} else
	439	prev = n;
	440	n = next;
	441	}
	442	}