[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_STAT
/*#define PULLDOWN_DEBUG*/

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

#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
88	#define PULLDOWN_STAT
89	/#define PULLDOWN_DEBUG/
90
91	#ifdef PULLDOWN_STAT
92	#if defined(__NetBSD__) \|\| (defined(__FreeBSD__) && __FreeBSD__ >= 3)
93	#include "opt_inet.h"
94	#endif
95	#endif
96
97	#include <sys/param.h>
98	#include <sys/systm.h>
99	#include <sys/proc.h>
100	#include <sys/malloc.h>
101	#include <sys/mbuf.h>
102	#if defined(PULLDOWN_STAT) && defined(INET6)
103	#include <netinet/in.h>
104	#include <netinet/ip6.h>
105	#include <netinet6/ip6_var.h>
106	#endif
107
108	/*
109	* ensure that [off, off + len) is contiguous on the mbuf chain "m".
110	* packet chain before "off" is kept untouched.
111	* if offp == NULL, the target will start at <retval, 0> on resulting chain.
112	* if offp != NULL, the target will start at <retval, *offp> on resulting chain.
113	*
114	* on error return (NULL return value), original "m" will be freed.
115	*
116	* XXX M_TRAILINGSPACE/M_LEADINGSPACE on shared cluster (sharedcluster)
117	*/
118	struct mbuf *
119	m_pulldown(m, off, len, offp)
120	struct mbuf *m;
121	int off, len;
122	int *offp;
123	{
124	struct mbuf n, o;
125	int hlen, tlen, olen;
126	int sharedcluster;
127	#if defined(PULLDOWN_STAT) && defined(INET6)
128	static struct mbuf *prev = NULL;
129	int prevlen = 0, prevmlen = 0;
130	#endif
131
132	/* check invalid arguments. */
133	if (m == NULL)
134	panic("m == NULL in m_pulldown()");
135	if (len > MCLBYTES) {
136	m_freem(m);
137	return NULL; /* impossible */
138	}
139
140	#if defined(PULLDOWN_STAT) && defined(INET6)
141	ip6stat.ip6s_pulldown++;
142	#endif
143
144	#if defined(PULLDOWN_STAT) && defined(INET6)
145	/* statistics for m_pullup */
146	ip6stat.ip6s_pullup++;
147	if (off + len > MHLEN)
148	ip6stat.ip6s_pullup_fail++;
149	else {
150	int dlen, mlen;
151
152	dlen = (prev == m) ? prevlen : m->m_len;
153	mlen = (prev == m) ? prevmlen : m->m_len + M_TRAILINGSPACE(m);
154
155	if (dlen >= off + len)
156	ip6stat.ip6s_pullup--; /* call will not be made! */
157	else if ((m->m_flags & M_EXT) != 0) {
158	ip6stat.ip6s_pullup_alloc++;
159	ip6stat.ip6s_pullup_copy++;
160	} else {
161	if (mlen >= off + len)
162	ip6stat.ip6s_pullup_copy++;
163	else {
164	ip6stat.ip6s_pullup_alloc++;
165	ip6stat.ip6s_pullup_copy++;
166	}
167	}
168
169	prevlen = off + len;
170	prevmlen = MHLEN;
171	}
172
173	/* statistics for m_pullup2 */
174	ip6stat.ip6s_pullup2++;
175	if (off + len > MCLBYTES)
176	ip6stat.ip6s_pullup2_fail++;
177	else {
178	int dlen, mlen;
179
180	dlen = (prev == m) ? prevlen : m->m_len;
181	mlen = (prev == m) ? prevmlen : m->m_len + M_TRAILINGSPACE(m);
182	prevlen = off + len;
183	prevmlen = mlen;
184
185	if (dlen >= off + len)
186	ip6stat.ip6s_pullup2--; /* call will not be made! */
187	else if ((m->m_flags & M_EXT) != 0) {
188	ip6stat.ip6s_pullup2_alloc++;
189	ip6stat.ip6s_pullup2_copy++;
190	prevmlen = (off + len > MHLEN) ? MCLBYTES : MHLEN;
191	} else {
192	if (mlen >= off + len)
193	ip6stat.ip6s_pullup2_copy++;
194	else {
195	ip6stat.ip6s_pullup2_alloc++;
196	ip6stat.ip6s_pullup2_copy++;
197	prevmlen = (off + len > MHLEN) ? MCLBYTES
198	: MHLEN;
199	}
200	}
201	}
202
203	prev = m;
204	#endif
205
206	#ifdef PULLDOWN_DEBUG
207	{
208	struct mbuf *t;
209	printf("before:");
210	for (t = m; t; t = t->m_next)
211	printf(" %d", t->m_len);
212	printf("\n");
213	}
214	#endif
215	n = m;
216	while (n != NULL && off > 0) {
217	if (n->m_len > off)
218	break;
219	off -= n->m_len;
220	n = n->m_next;
221	}
222	/* be sure to point non-empty mbuf */
223	while (n != NULL && n->m_len == 0)
224	n = n->m_next;
225	if (!n) {
226	m_freem(m);
227	return NULL; /* mbuf chain too short */
228	}
229
230	/*
231	* the target data is on <n, off>.
232	* if we got enough data on the mbuf "n", we're done.
233	*/
234	if ((off == 0 \|\| offp) && len <= n->m_len - off)
235	goto ok;
236
237	#if defined(PULLDOWN_STAT) && defined(INET6)
238	ip6stat.ip6s_pulldown_copy++;
239	#endif
240
241	/*
242	* when len < n->m_len - off and off != 0, it is a special case.
243	* len bytes from <n, off> sits in single mbuf, but the caller does
244	* not like the starting position (off).
245	* chop the current mbuf into two pieces, set off to 0.
246	*/
247	if (len < n->m_len - off) {
248	o = m_copym(n, off, n->m_len - off, M_DONTWAIT);
249	if (o == NULL) {
250	m_freem(m);
251	return NULL; /* ENOBUFS */
252	}
253	n->m_len = off;
254	o->m_next = n->m_next;
255	n->m_next = o;
256	n = n->m_next;
257	off = 0;
258	goto ok;
259	}
260
261	/*
262	* we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
263	* and construct contiguous mbuf with m_len == len.
264	* note that hlen + tlen == len, and tlen > 0.
265	*/
266	hlen = n->m_len - off;
267	tlen = len - hlen;
268
269	/*
270	* ensure that we have enough trailing data on mbuf chain.
271	* if not, we can do nothing about the chain.
272	*/
273	olen = 0;
274	for (o = n->m_next; o != NULL; o = o->m_next)
275	olen += o->m_len;
276	if (hlen + olen < len) {
277	m_freem(m);
278	return NULL; /* mbuf chain too short */
279	}
280
281	/*
282	* easy cases first.
283	* we need to use m_copydata() to get data from <n->m_next, 0>.
284	*/
285	if ((n->m_flags & M_EXT) == 0)
286	sharedcluster = 0;
287	else {
288	#ifdef __bsdi__
289	if (n->m_ext.ext_func)
290	#else
291	if (n->m_ext.ext_free)
292	#endif
293	sharedcluster = 1;
294	#ifdef __NetBSD__
295	else if (MCLISREFERENCED(n))
296	#else
297	else if (mclrefcnt[mtocl(n->m_ext.ext_buf)] > 1)
298	#endif
299	sharedcluster = 1;
300	else
301	sharedcluster = 0;
302	}
303	if ((off == 0 \|\| offp) && M_TRAILINGSPACE(n) >= tlen
304	&& !sharedcluster) {
305	m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
306	n->m_len += tlen;
307	m_adj(n->m_next, tlen);
308	goto ok;
309	}
310	if ((off == 0 \|\| offp) && M_LEADINGSPACE(n->m_next) >= hlen
311	&& !sharedcluster) {
312	n->m_next->m_data -= hlen;
313	n->m_next->m_len += hlen;
314	bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
315	n->m_len -= hlen;
316	n = n->m_next;
317	off = 0;
318	goto ok;
319	}
320
321	/*
322	* now, we need to do the hard way. don't m_copy as there's no room
323	* on both end.
324	*/
325	#if defined(PULLDOWN_STAT) && defined(INET6)
326	ip6stat.ip6s_pulldown_alloc++;
327	#endif
328	MGET(o, M_DONTWAIT, m->m_type);
329	if (o == NULL) {
330	m_freem(m);
331	return NULL; /* ENOBUFS */
332	}
333	if (len > MHLEN) { /* use MHLEN just for safety */
334	MCLGET(o, M_DONTWAIT);
335	if ((o->m_flags & M_EXT) == 0) {
336	m_freem(m);
337	m_free(o);
338	return NULL; /* ENOBUFS */
339	}
340	}
341	/* get hlen from <n, off> into <o, 0> */
342	o->m_len = hlen;
343	bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
344	n->m_len -= hlen;
345	/* get tlen from <n->m_next, 0> into <o, hlen> */
346	m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
347	o->m_len += tlen;
348	m_adj(n->m_next, tlen);
349	o->m_next = n->m_next;
350	n->m_next = o;
351	n = o;
352	off = 0;
353
354	ok:
355	#ifdef PULLDOWN_DEBUG
356	{
357	struct mbuf *t;
358	printf("after:");
359	for (t = m; t; t = t->m_next)
360	printf("%c%d", t == n ? '*' : ' ', t->m_len);
361	printf(" (off=%d)\n", off);
362	}
363	#endif
364	if (offp)
365	*offp = off;
366	return n;
367	}
368
369	/*
370	* pkthdr.aux chain manipulation.
371	* we don't allow clusters at this moment.
372	*/
373	struct mbuf *
374	m_aux_add(m, af, type)
375	struct mbuf *m;
376	int af, type;
377	{
378	struct mbuf *n;
379	struct mauxtag *t;
380
381	if ((m->m_flags & M_PKTHDR) == 0)
382	return NULL;
383
384	n = m_aux_find(m, af, type);
385	if (n)
386	return n;
387
0b4e3aa0	388	MGET(n, M_WAIT, m->m_type);
1c79356b A	389	if (n == NULL)
	390	return NULL;
	391
	392	t = mtod(n, struct mauxtag *);
	393	t->af = af;
	394	t->type = type;
	395	n->m_data += sizeof(struct mauxtag);
	396	n->m_len = 0;
	397	n->m_next = m->m_pkthdr.aux;
	398	m->m_pkthdr.aux = n;
	399	return n;
	400	}
	401
	402	struct mbuf *
	403	m_aux_find(m, af, type)
	404	struct mbuf *m;
	405	int af, type;
	406	{
	407	struct mbuf *n;
	408	struct mauxtag *t;
	409
	410	if ((m->m_flags & M_PKTHDR) == 0)
	411	return NULL;
	412
	413	for (n = m->m_pkthdr.aux; n; n = n->m_next) {
	414	t = (struct mauxtag *)n->m_dat;
	415	if (t->af == af && t->type == type)
	416	return n;
	417	}
	418	return NULL;
	419	}
	420
	421	void
	422	m_aux_delete(m, victim)
	423	struct mbuf *m;
	424	struct mbuf *victim;
	425	{
	426	struct mbuf n, prev, *next;
	427	struct mauxtag *t;
	428
	429	if ((m->m_flags & M_PKTHDR) == 0)
	430	return;
	431
	432	prev = NULL;
	433	n = m->m_pkthdr.aux;
	434	while (n) {
	435	t = (struct mauxtag *)n->m_dat;
	436	next = n->m_next;
	437	if (n == victim) {
	438	if (prev)
	439	prev->m_next = n->m_next;
	440	else
	441	m->m_pkthdr.aux = n->m_next;
	442	n->m_next = NULL;
	443	m_free(n);
	444	} else
	445	prev = n;
	446	n = next;
	447	}
	448	}