454 lines
13 KiB
C
454 lines
13 KiB
C
/* $KAME: uipc_mbuf2.c,v 1.31 2001/11/28 11:08:53 itojun Exp $ */
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/* $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $ */
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/*-
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* Copyright (C) 1999 WIDE Project.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the project nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*-
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* Copyright (c) 1982, 1986, 1988, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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/*#define PULLDOWN_DEBUG*/
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#include "opt_mac.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mac.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/mutex.h>
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static MALLOC_DEFINE(M_PACKET_TAGS, "mbuf tags", "packet-attached information");
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/* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
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static struct mbuf *m_dup1(struct mbuf *, int, int, int);
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/*
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* ensure that [off, off + len) is contiguous on the mbuf chain "m".
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* packet chain before "off" is kept untouched.
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* if offp == NULL, the target will start at <retval, 0> on resulting chain.
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* if offp != NULL, the target will start at <retval, *offp> on resulting chain.
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*
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* on error return (NULL return value), original "m" will be freed.
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*
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* XXX: M_TRAILINGSPACE/M_LEADINGSPACE only permitted on writable ext_buf.
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*/
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struct mbuf *
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m_pulldown(struct mbuf *m, int off, int len, int *offp)
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{
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struct mbuf *n, *o;
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int hlen, tlen, olen;
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int writable;
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/* check invalid arguments. */
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if (m == NULL)
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panic("m == NULL in m_pulldown()");
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if (len > MCLBYTES) {
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m_freem(m);
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return NULL; /* impossible */
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}
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#ifdef PULLDOWN_DEBUG
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{
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struct mbuf *t;
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printf("before:");
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for (t = m; t; t = t->m_next)
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printf(" %d", t->m_len);
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printf("\n");
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}
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#endif
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n = m;
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while (n != NULL && off > 0) {
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if (n->m_len > off)
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break;
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off -= n->m_len;
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n = n->m_next;
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}
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/* be sure to point non-empty mbuf */
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while (n != NULL && n->m_len == 0)
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n = n->m_next;
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if (!n) {
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m_freem(m);
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return NULL; /* mbuf chain too short */
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}
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/*
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* XXX: This code is flawed because it considers a "writable" mbuf
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* data region to require all of the following:
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* (i) mbuf _has_ to have M_EXT set; if it is just a regular
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* mbuf, it is still not considered "writable."
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* (ii) since mbuf has M_EXT, the ext_type _has_ to be
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* EXT_CLUSTER. Anything else makes it non-writable.
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* (iii) M_WRITABLE() must evaluate true.
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* Ideally, the requirement should only be (iii).
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*
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* If we're writable, we're sure we're writable, because the ref. count
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* cannot increase from 1, as that would require posession of mbuf
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* n by someone else (which is impossible). However, if we're _not_
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* writable, we may eventually become writable )if the ref. count drops
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* to 1), but we'll fail to notice it unless we re-evaluate
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* M_WRITABLE(). For now, we only evaluate once at the beginning and
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* live with this.
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*/
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/*
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* XXX: This is dumb. If we're just a regular mbuf with no M_EXT,
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* then we're not "writable," according to this code.
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*/
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writable = 0;
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if ((n->m_flags & M_EXT) == 0 ||
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(n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n)))
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writable = 1;
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/*
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* the target data is on <n, off>.
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* if we got enough data on the mbuf "n", we're done.
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*/
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if ((off == 0 || offp) && len <= n->m_len - off && writable)
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goto ok;
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/*
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* when len <= n->m_len - off and off != 0, it is a special case.
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* len bytes from <n, off> sits in single mbuf, but the caller does
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* not like the starting position (off).
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* chop the current mbuf into two pieces, set off to 0.
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*/
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if (len <= n->m_len - off) {
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o = m_dup1(n, off, n->m_len - off, M_DONTWAIT);
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if (o == NULL) {
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m_freem(m);
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return NULL; /* ENOBUFS */
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}
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n->m_len = off;
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o->m_next = n->m_next;
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n->m_next = o;
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n = n->m_next;
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off = 0;
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goto ok;
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}
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/*
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* we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
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* and construct contiguous mbuf with m_len == len.
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* note that hlen + tlen == len, and tlen > 0.
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*/
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hlen = n->m_len - off;
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tlen = len - hlen;
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/*
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* ensure that we have enough trailing data on mbuf chain.
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* if not, we can do nothing about the chain.
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*/
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olen = 0;
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for (o = n->m_next; o != NULL; o = o->m_next)
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olen += o->m_len;
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if (hlen + olen < len) {
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m_freem(m);
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return NULL; /* mbuf chain too short */
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}
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/*
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* easy cases first.
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* we need to use m_copydata() to get data from <n->m_next, 0>.
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*/
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if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen
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&& writable) {
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m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
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n->m_len += tlen;
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m_adj(n->m_next, tlen);
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goto ok;
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}
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if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen
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&& writable) {
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n->m_next->m_data -= hlen;
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n->m_next->m_len += hlen;
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bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
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n->m_len -= hlen;
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n = n->m_next;
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off = 0;
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goto ok;
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}
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/*
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* now, we need to do the hard way. don't m_copy as there's no room
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* on both end.
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*/
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if (len > MLEN)
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o = m_getcl(M_DONTWAIT, m->m_type, 0);
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else
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o = m_get(M_DONTWAIT, m->m_type);
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if (!o) {
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m_freem(m);
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return NULL; /* ENOBUFS */
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}
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/* get hlen from <n, off> into <o, 0> */
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o->m_len = hlen;
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bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
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n->m_len -= hlen;
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/* get tlen from <n->m_next, 0> into <o, hlen> */
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m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
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o->m_len += tlen;
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m_adj(n->m_next, tlen);
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o->m_next = n->m_next;
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n->m_next = o;
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n = o;
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off = 0;
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ok:
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#ifdef PULLDOWN_DEBUG
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{
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struct mbuf *t;
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printf("after:");
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for (t = m; t; t = t->m_next)
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printf("%c%d", t == n ? '*' : ' ', t->m_len);
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printf(" (off=%d)\n", off);
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}
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#endif
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if (offp)
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*offp = off;
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return n;
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}
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static struct mbuf *
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m_dup1(struct mbuf *m, int off, int len, int wait)
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{
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struct mbuf *n;
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int copyhdr;
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if (len > MCLBYTES)
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return NULL;
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if (off == 0 && (m->m_flags & M_PKTHDR) != 0)
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copyhdr = 1;
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else
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copyhdr = 0;
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if (len >= MINCLSIZE) {
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if (copyhdr == 1)
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n = m_getcl(wait, m->m_type, M_PKTHDR);
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else
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n = m_getcl(wait, m->m_type, 0);
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} else {
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if (copyhdr == 1)
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n = m_gethdr(wait, m->m_type);
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else
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n = m_get(wait, m->m_type);
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}
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if (!n)
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return NULL; /* ENOBUFS */
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if (copyhdr && !m_dup_pkthdr(n, m, wait)) {
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m_free(n);
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return NULL;
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}
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m_copydata(m, off, len, mtod(n, caddr_t));
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n->m_len = len;
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return n;
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}
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/* Free a packet tag. */
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void
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m_tag_free_default(struct m_tag *t)
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{
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#ifdef MAC
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if (t->m_tag_id == PACKET_TAG_MACLABEL)
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mac_destroy_mbuf_tag(t);
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#endif
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free(t, M_PACKET_TAGS);
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}
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/* Get a packet tag structure along with specified data following. */
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struct m_tag *
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m_tag_alloc(u_int32_t cookie, int type, int len, int wait)
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{
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struct m_tag *t;
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MBUF_CHECKSLEEP(wait);
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if (len < 0)
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return NULL;
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t = malloc(len + sizeof(struct m_tag), M_PACKET_TAGS, wait);
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if (t == NULL)
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return NULL;
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m_tag_setup(t, cookie, type, len);
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t->m_tag_free = m_tag_free_default;
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return t;
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}
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/* Unlink and free a packet tag. */
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void
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m_tag_delete(struct mbuf *m, struct m_tag *t)
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{
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KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
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m_tag_unlink(m, t);
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m_tag_free(t);
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}
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/* Unlink and free a packet tag chain, starting from given tag. */
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void
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m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
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{
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struct m_tag *p, *q;
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KASSERT(m, ("m_tag_delete_chain: null mbuf"));
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if (t != NULL)
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p = t;
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else
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p = SLIST_FIRST(&m->m_pkthdr.tags);
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if (p == NULL)
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return;
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while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
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m_tag_delete(m, q);
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m_tag_delete(m, p);
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}
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/*
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* Strip off all tags that would normally vanish when
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* passing through a network interface. Only persistent
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* tags will exist after this; these are expected to remain
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* so long as the mbuf chain exists, regardless of the
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* path the mbufs take.
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*/
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void
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m_tag_delete_nonpersistent(struct mbuf *m)
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{
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struct m_tag *p, *q;
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SLIST_FOREACH_SAFE(p, &m->m_pkthdr.tags, m_tag_link, q)
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if ((p->m_tag_id & MTAG_PERSISTENT) == 0)
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m_tag_delete(m, p);
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}
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/* Find a tag, starting from a given position. */
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struct m_tag *
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m_tag_locate(struct mbuf *m, u_int32_t cookie, int type, struct m_tag *t)
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{
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struct m_tag *p;
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KASSERT(m, ("m_tag_locate: null mbuf"));
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if (t == NULL)
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p = SLIST_FIRST(&m->m_pkthdr.tags);
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else
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p = SLIST_NEXT(t, m_tag_link);
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while (p != NULL) {
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if (p->m_tag_cookie == cookie && p->m_tag_id == type)
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return p;
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p = SLIST_NEXT(p, m_tag_link);
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}
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return NULL;
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}
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/* Copy a single tag. */
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struct m_tag *
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m_tag_copy(struct m_tag *t, int how)
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{
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struct m_tag *p;
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MBUF_CHECKSLEEP(how);
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KASSERT(t, ("m_tag_copy: null tag"));
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p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
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if (p == NULL)
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return (NULL);
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#ifdef MAC
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/*
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* XXXMAC: we should probably pass off the initialization, and
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* copying here? can we hide that PACKET_TAG_MACLABEL is
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* special from the mbuf code?
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*/
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if (t->m_tag_id == PACKET_TAG_MACLABEL) {
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if (mac_init_mbuf_tag(p, how) != 0) {
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m_tag_free(p);
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return (NULL);
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}
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mac_copy_mbuf_tag(t, p);
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} else
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#endif
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bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
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return p;
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}
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/*
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* Copy two tag chains. The destination mbuf (to) loses any attached
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* tags even if the operation fails. This should not be a problem, as
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* m_tag_copy_chain() is typically called with a newly-allocated
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* destination mbuf.
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*/
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int
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m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how)
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{
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struct m_tag *p, *t, *tprev = NULL;
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MBUF_CHECKSLEEP(how);
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KASSERT(to && from,
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("m_tag_copy_chain: null argument, to %p from %p", to, from));
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m_tag_delete_chain(to, NULL);
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SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
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t = m_tag_copy(p, how);
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if (t == NULL) {
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m_tag_delete_chain(to, NULL);
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return 0;
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}
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if (tprev == NULL)
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SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
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else
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SLIST_INSERT_AFTER(tprev, t, m_tag_link);
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tprev = t;
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}
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return 1;
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}
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