The Tor Browser: netwerk/sctp/src/user_mbuf.c@6474c204b198 (annotated)

netwerk/sctp/src/user_mbuf.c@6474c204b198 (annotated)

netwerk/sctp/src/user_mbuf.c

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rwxr-xr-x

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /*-
  * Copyright (c) 1982, 1986, 1988, 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. 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.
  *
  */
 /*
  *  __Userspace__ version of /usr/src/sys/kern/kern_mbuf.c
  *  We are initializing two zones for Mbufs and Clusters.
  *
  */
 #include <stdio.h>
 #include <string.h>
 /* #include <sys/param.h> This defines MSIZE 256 */
 #if !defined(SCTP_SIMPLE_ALLOCATOR)
 #include "umem.h"
 #endif
 #include "user_mbuf.h"
 #include "user_environment.h"
 #include "user_atomic.h"
 #include "netinet/sctp_pcb.h"
 struct mbstat mbstat;
 #define KIPC_MAX_LINKHDR        4       /* int: max length of link header (see sys/sysclt.h) */
 #define KIPC_MAX_PROTOHDR	5	/* int: max length of network header (see sys/sysclt.h)*/
 int max_linkhdr = KIPC_MAX_LINKHDR;
 int max_protohdr = KIPC_MAX_PROTOHDR; /* Size of largest protocol layer header. */
 /*
  * Zones from which we allocate.
  */
 sctp_zone_t	zone_mbuf;
 sctp_zone_t	zone_clust;
 sctp_zone_t	zone_ext_refcnt;
 /* __Userspace__ clust_mb_args will be passed as callback data to mb_ctor_clust
  * and mb_dtor_clust.
  * Note: I had to use struct clust_args as an encapsulation for an mbuf pointer.
  * struct mbuf * clust_mb_args; does not work.
  */
 struct clust_args clust_mb_args;
 /* __Userspace__
  * Local prototypes.
  */
 static int	mb_ctor_mbuf(void *, void *, int);
 static int      mb_ctor_clust(void *, void *, int);
 static void	mb_dtor_mbuf(void *,  void *);
 static void	mb_dtor_clust(void *, void *);
 /***************** Functions taken from user_mbuf.h *************/
 static int mbuf_constructor_dup(struct mbuf *m, int pkthdr, short type)
 {
 	int flags = pkthdr;
 	if (type == MT_NOINIT)
 		return (0);
 	m->m_next = NULL;
 	m->m_nextpkt = NULL;
 	m->m_len = 0;
 	m->m_flags = flags;
 	m->m_type = type;
 	if (flags & M_PKTHDR) {
 		m->m_data = m->m_pktdat;
 		m->m_pkthdr.rcvif = NULL;
 		m->m_pkthdr.len = 0;
 		m->m_pkthdr.header = NULL;
 		m->m_pkthdr.csum_flags = 0;
 		m->m_pkthdr.csum_data = 0;
 		m->m_pkthdr.tso_segsz = 0;
 		m->m_pkthdr.ether_vtag = 0;
 		SLIST_INIT(&m->m_pkthdr.tags);
 	} else
 		m->m_data = m->m_dat;
 	return (0);
 }
 /* __Userspace__ */
 struct mbuf *
 m_get(int how, short type)
 {
 	struct mbuf *mret;
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 	struct mb_args mbuf_mb_args;
 	/* The following setter function is not yet being enclosed within
 	 * #if USING_MBUF_CONSTRUCTOR - #endif, until I have thoroughly tested
 	 * mb_dtor_mbuf. See comment there
 	 */
 	mbuf_mb_args.flags = 0;
 	mbuf_mb_args.type = type;
 #endif
 	/* Mbuf master zone, zone_mbuf, has already been
 	 * created in mbuf_init() */
 	mret = SCTP_ZONE_GET(zone_mbuf, struct mbuf);
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 	mb_ctor_mbuf(mret, &mbuf_mb_args, 0);
 #endif
 	/*mret =  ((struct mbuf *)umem_cache_alloc(zone_mbuf, UMEM_DEFAULT));*/
 	/* There are cases when an object available in the current CPU's
 	 * loaded magazine and in those cases the object's constructor is not applied.
 	 * If that is the case, then we are duplicating constructor initialization here,
 	 * so that the mbuf is properly constructed before returning it.
 	 */
 	if (mret) {
 #if USING_MBUF_CONSTRUCTOR
 		if (! (mret->m_type == type) ) {
 			mbuf_constructor_dup(mret, 0, type);
 		}
 #else
 		mbuf_constructor_dup(mret, 0, type);
 #endif
 	}
 	return mret;
 }
 /* __Userspace__ */
 struct mbuf *
 m_gethdr(int how, short type)
 {
 	struct mbuf *mret;
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 	struct mb_args mbuf_mb_args;
 	/* The following setter function is not yet being enclosed within
 	 * #if USING_MBUF_CONSTRUCTOR - #endif, until I have thoroughly tested
 	 * mb_dtor_mbuf. See comment there
 	 */
 	mbuf_mb_args.flags = M_PKTHDR;
 	mbuf_mb_args.type = type;
 #endif
 	mret = SCTP_ZONE_GET(zone_mbuf, struct mbuf);
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 	mb_ctor_mbuf(mret, &mbuf_mb_args, 0);
 #endif
 	/*mret = ((struct mbuf *)umem_cache_alloc(zone_mbuf, UMEM_DEFAULT));*/
 	/* There are cases when an object available in the current CPU's
 	 * loaded magazine and in those cases the object's constructor is not applied.
 	 * If that is the case, then we are duplicating constructor initialization here,
 	 * so that the mbuf is properly constructed before returning it.
 	 */
 	if (mret) {
 #if USING_MBUF_CONSTRUCTOR
 		if (! ((mret->m_flags & M_PKTHDR) && (mret->m_type == type)) ) {
 			mbuf_constructor_dup(mret, M_PKTHDR, type);
 		}
 #else
 		mbuf_constructor_dup(mret, M_PKTHDR, type);
 #endif
 	}
 	return mret;
 }
 /* __Userspace__ */
 struct mbuf *
 m_free(struct mbuf *m)
 {
 	struct mbuf *n = m->m_next;
 	if (m->m_flags & M_EXT)
 		mb_free_ext(m);
 	else if ((m->m_flags & M_NOFREE) == 0) {
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 		mb_dtor_mbuf(m, NULL);
 #endif
 		SCTP_ZONE_FREE(zone_mbuf, m);
 	}
 		/*umem_cache_free(zone_mbuf, m);*/
 	return (n);
 }
 static int clust_constructor_dup(caddr_t m_clust, struct mbuf* m)
 {
 	u_int *refcnt;
 	int type, size;
 	/* Assigning cluster of MCLBYTES. TODO: Add jumbo frame functionality */
 	type = EXT_CLUSTER;
 	size = MCLBYTES;
 	refcnt = SCTP_ZONE_GET(zone_ext_refcnt, u_int);
 	/*refcnt = (u_int *)umem_cache_alloc(zone_ext_refcnt, UMEM_DEFAULT);*/
 	if (refcnt == NULL) {
 #if !defined(SCTP_SIMPLE_ALLOCATOR)
 		umem_reap();
 #endif
 		refcnt = SCTP_ZONE_GET(zone_ext_refcnt, u_int);
 		/*refcnt = (u_int *)umem_cache_alloc(zone_ext_refcnt, UMEM_DEFAULT);*/
 	}
 	*refcnt = 1;
 	if (m != NULL) {
 		m->m_ext.ext_buf = (caddr_t)m_clust;
 		m->m_data = m->m_ext.ext_buf;
 		m->m_flags |= M_EXT;
 		m->m_ext.ext_free = NULL;
 		m->m_ext.ext_args = NULL;
 		m->m_ext.ext_size = size;
 		m->m_ext.ext_type = type;
 		m->m_ext.ref_cnt = refcnt;
 	}
 	return (0);
 }
 /* __Userspace__ */
 void
 m_clget(struct mbuf *m, int how)
 {
 	caddr_t mclust_ret;
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 	struct clust_args clust_mb_args;
 #endif
 	if (m->m_flags & M_EXT) {
 		SCTPDBG(SCTP_DEBUG_USR, "%s: %p mbuf already has cluster\n", __func__, (void *)m);
 	}
 	m->m_ext.ext_buf = (char *)NULL;
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 	clust_mb_args.parent_mbuf = m;
 #endif
 	mclust_ret = SCTP_ZONE_GET(zone_clust, char);
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 	mb_ctor_clust(mclust_ret, &clust_mb_args, 0);
 #endif
 	/*mclust_ret = umem_cache_alloc(zone_clust, UMEM_DEFAULT);*/
 	/*
 	 On a cluster allocation failure, call umem_reap() and retry.
 	 */
 	if (mclust_ret == NULL) {
 #if !defined(SCTP_SIMPLE_ALLOCATOR)
 	/*	mclust_ret = SCTP_ZONE_GET(zone_clust, char);
 		mb_ctor_clust(mclust_ret, &clust_mb_args, 0);
 #else*/
 		umem_reap();
 		mclust_ret = SCTP_ZONE_GET(zone_clust, char);
 #endif
 		/*mclust_ret = umem_cache_alloc(zone_clust, UMEM_DEFAULT);*/
 		if (NULL == mclust_ret) {
 			SCTPDBG(SCTP_DEBUG_USR, "Memory allocation failure in %s\n", __func__);
 		}
 	}
 #if USING_MBUF_CONSTRUCTOR
 	if ((m->m_ext.ext_buf == NULL)) {
 		clust_constructor_dup(mclust_ret, m);
 	}
 #else
 	clust_constructor_dup(mclust_ret, m);
 #endif
 }
 /*
  * Unlink a tag from the list of tags associated with an mbuf.
  */
 static __inline void
 m_tag_unlink(struct mbuf *m, struct m_tag *t)
 {
 	SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
 }
 /*
  * Reclaim resources associated with a tag.
  */
 static __inline void
 m_tag_free(struct m_tag *t)
 {
 	(*t->m_tag_free)(t);
 }
 /*
  * Set up the contents of a tag.  Note that this does not fill in the free
  * method; the caller is expected to do that.
  *
  * XXX probably should be called m_tag_init, but that was already taken.
  */
 static __inline void
 m_tag_setup(struct m_tag *t, u_int32_t cookie, int type, int len)
 {
 	t->m_tag_id = type;
 	t->m_tag_len = len;
 	t->m_tag_cookie = cookie;
 }
 /************ End functions from user_mbuf.h  ******************/
 /************ End functions to substitute umem_cache_alloc and umem_cache_free **************/
 /* __Userspace__
  * TODO: mbuf_init must be called in the initialization routines
  * of userspace stack.
  */
 void
 mbuf_init(void *dummy)
 {
 	/*
 	 * __Userspace__Configure UMA zones for Mbufs and Clusters.
 	 * (TODO: m_getcl() - using packet secondary zone).
 	 * There is no provision for trash_init and trash_fini in umem.
 	 *
 	 */
  /* zone_mbuf = umem_cache_create(MBUF_MEM_NAME, MSIZE, 0,
 				mb_ctor_mbuf, mb_dtor_mbuf, NULL,
 				&mbuf_mb_args,
 				NULL, 0);
 	zone_mbuf = umem_cache_create(MBUF_MEM_NAME, MSIZE, 0, NULL, NULL, NULL, NULL, NULL, 0);*/
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 	SCTP_ZONE_INIT(zone_mbuf, MBUF_MEM_NAME, MSIZE, 0);
 #else
 	zone_mbuf = umem_cache_create(MBUF_MEM_NAME, MSIZE, 0,
 	                              mb_ctor_mbuf, mb_dtor_mbuf, NULL,
 	                              NUULL,
 	                              NULL, 0);
 #endif
 	/*zone_ext_refcnt = umem_cache_create(MBUF_EXTREFCNT_MEM_NAME, sizeof(u_int), 0,
 				NULL, NULL, NULL,
 				NULL,
 				NULL, 0);*/
 	SCTP_ZONE_INIT(zone_ext_refcnt, MBUF_EXTREFCNT_MEM_NAME, sizeof(u_int), 0);
   /*zone_clust = umem_cache_create(MBUF_CLUSTER_MEM_NAME, MCLBYTES, 0,
 				 mb_ctor_clust, mb_dtor_clust, NULL,
 				 &clust_mb_args,
 				 NULL, 0);
 	zone_clust = umem_cache_create(MBUF_CLUSTER_MEM_NAME, MCLBYTES, 0, NULL, NULL, NULL, NULL, NULL,0);*/
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 	SCTP_ZONE_INIT(zone_clust, MBUF_CLUSTER_MEM_NAME, MCLBYTES, 0);
 #else
 	zone_clust = umem_cache_create(MBUF_CLUSTER_MEM_NAME, MCLBYTES, 0,
 								   mb_ctor_clust, mb_dtor_clust, NULL,
 								   &clust_mb_args,
 								   NULL, 0);
 #endif
 	/* uma_prealloc() goes here... */
 	/* __Userspace__ Add umem_reap here for low memory situation?
 	 *
 	 */
 	/*
 	 * [Re]set counters and local statistics knobs.
 	 *
 	 */
 	mbstat.m_mbufs = 0;
 	mbstat.m_mclusts = 0;
 	mbstat.m_drain = 0;
 	mbstat.m_msize = MSIZE;
 	mbstat.m_mclbytes = MCLBYTES;
 	mbstat.m_minclsize = MINCLSIZE;
 	mbstat.m_mlen = MLEN;
 	mbstat.m_mhlen = MHLEN;
 	mbstat.m_numtypes = MT_NTYPES;
 	mbstat.m_mcfail = mbstat.m_mpfail = 0;
 	mbstat.sf_iocnt = 0;
 	mbstat.sf_allocwait = mbstat.sf_allocfail = 0;
 }
 /*
  * __Userspace__
  *
  * Constructor for Mbuf master zone. We have a different constructor
  * for allocating the cluster.
  *
  * The 'arg' pointer points to a mb_args structure which
  * contains call-specific information required to support the
  * mbuf allocation API.  See user_mbuf.h.
  *
  * The flgs parameter below can be UMEM_DEFAULT or UMEM_NOFAIL depending on what
  * was passed when umem_cache_alloc was called.
  * TODO: Use UMEM_NOFAIL in umem_cache_alloc and also define a failure handler
  * and call umem_nofail_callback(my_failure_handler) in the stack initialization routines
  * The advantage of using UMEM_NOFAIL is that we don't have to check if umem_cache_alloc
  * was successful or not. The failure handler would take care of it, if we use the UMEM_NOFAIL
  * flag.
  *
  * NOTE Ref: http://docs.sun.com/app/docs/doc/819-2243/6n4i099p2?l=en&a=view&q=umem_zalloc)
  * The umem_nofail_callback() function sets the **process-wide** UMEM_NOFAIL callback.
  * It also mentions that umem_nofail_callback is Evolving.
  *
  */
 static int
 mb_ctor_mbuf(void *mem, void *arg, int flgs)
 {
 #if USING_MBUF_CONSTRUCTOR
 	struct mbuf *m;
 	struct mb_args *args;
 	int flags;
 	short type;
 	m = (struct mbuf *)mem;
 	args = (struct mb_args *)arg;
 	flags = args->flags;
 	type = args->type;
 	/*
 	 * The mbuf is initialized later.
 	 *
 	 */
 	if (type == MT_NOINIT)
 		return (0);
 	m->m_next = NULL;
 	m->m_nextpkt = NULL;
 	m->m_len = 0;
 	m->m_flags = flags;
 	m->m_type = type;
 	if (flags & M_PKTHDR) {
 		m->m_data = m->m_pktdat;
 		m->m_pkthdr.rcvif = NULL;
 		m->m_pkthdr.len = 0;
 		m->m_pkthdr.header = NULL;
 		m->m_pkthdr.csum_flags = 0;
 		m->m_pkthdr.csum_data = 0;
 		m->m_pkthdr.tso_segsz = 0;
 		m->m_pkthdr.ether_vtag = 0;
 		SLIST_INIT(&m->m_pkthdr.tags);
 	} else
 		m->m_data = m->m_dat;
 #endif
 	return (0);
 }
 /*
  * __Userspace__
  * The Mbuf master zone destructor.
  * This would be called in response to umem_cache_destroy
  * TODO: Recheck if this is what we want to do in this destructor.
  * (Note: the number of times mb_dtor_mbuf is called is equal to the
  * number of individual mbufs allocated from zone_mbuf.
  */
 static void
 mb_dtor_mbuf(void *mem, void *arg)
 {
 	struct mbuf *m;
 	m = (struct mbuf *)mem;
 	if ((m->m_flags & M_PKTHDR) != 0) {
 		m_tag_delete_chain(m, NULL);
 	}
 }
 /* __Userspace__
  * The Cluster zone constructor.
  *
  * Here the 'arg' pointer points to the Mbuf which we
  * are configuring cluster storage for.  If 'arg' is
  * empty we allocate just the cluster without setting
  * the mbuf to it.  See mbuf.h.
  */
 static int
 mb_ctor_clust(void *mem, void *arg, int flgs)
 {
 #if USING_MBUF_CONSTRUCTOR
 	struct mbuf *m;
 	struct clust_args * cla;
 	u_int *refcnt;
 	int type, size;
 	sctp_zone_t zone;
 	/* Assigning cluster of MCLBYTES. TODO: Add jumbo frame functionality */
 	type = EXT_CLUSTER;
 	zone = zone_clust;
 	size = MCLBYTES;
 	cla = (struct clust_args *)arg;
 	m = cla->parent_mbuf;
 	refcnt = SCTP_ZONE_GET(zone_ext_refcnt, u_int);
 	/*refcnt = (u_int *)umem_cache_alloc(zone_ext_refcnt, UMEM_DEFAULT);*/
 	*refcnt = 1;
 	if (m != NULL) {
 		m->m_ext.ext_buf = (caddr_t)mem;
 		m->m_data = m->m_ext.ext_buf;
 		m->m_flags |= M_EXT;
 		m->m_ext.ext_free = NULL;
 		m->m_ext.ext_args = NULL;
 		m->m_ext.ext_size = size;
 		m->m_ext.ext_type = type;
 		m->m_ext.ref_cnt = refcnt;
 	}
 #endif
 	return (0);
 }
 /* __Userspace__ */
 static void
 mb_dtor_clust(void *mem, void *arg)
 {
   /* mem is of type caddr_t.  In sys/types.h we have typedef char * caddr_t;  */
   /* mb_dtor_clust is called at time of umem_cache_destroy() (the number of times
    * mb_dtor_clust is called is equal to the number of individual mbufs allocated
    * from zone_clust. Similarly for mb_dtor_mbuf).
    * At this point the following:
    *  struct mbuf *m;
    *   m = (struct mbuf *)arg;
    *  assert (*(m->m_ext.ref_cnt) == 0); is not meaningful since  m->m_ext.ref_cnt = NULL;
    *  has been done in mb_free_ext().
    */
 }
 /* Unlink and free a packet tag. */
 void
 m_tag_delete(struct mbuf *m, struct m_tag *t)
 {
 	KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", (void *)m, (void *)t));
 	m_tag_unlink(m, t);
 	m_tag_free(t);
 }
 /* Unlink and free a packet tag chain, starting from given tag. */
 void
 m_tag_delete_chain(struct mbuf *m, struct m_tag *t)
 {
 	struct m_tag *p, *q;
 	KASSERT(m, ("m_tag_delete_chain: null mbuf"));
 	if (t != NULL)
 		p = t;
 	else
 		p = SLIST_FIRST(&m->m_pkthdr.tags);
 	if (p == NULL)
 		return;
 	while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
 		m_tag_delete(m, q);
 	m_tag_delete(m, p);
 }
 #if 0
 static void
 sctp_print_mbuf_chain(struct mbuf *m)
 {
 	SCTP_DEBUG_USR(SCTP_DEBUG_USR, "Printing mbuf chain %p.\n", (void *)m);
 	for(; m; m=m->m_next) {
 		SCTP_DEBUG_USR(SCTP_DEBUG_USR, "%p: m_len = %ld, m_type = %x, m_next = %p.\n", (void *)m, m->m_len, m->m_type, (void *)m->m_next);
 		if (m->m_flags & M_EXT)
 			SCTP_DEBUG_USR(SCTP_DEBUG_USR, "%p: extend_size = %d, extend_buffer = %p, ref_cnt = %d.\n", (void *)m, m->m_ext.ext_size, (void *)m->m_ext.ext_buf, *(m->m_ext.ref_cnt));
 	}
 }
 #endif
 /*
  * Free an entire chain of mbufs and associated external buffers, if
  * applicable.
  */
 void
 m_freem(struct mbuf *mb)
 {
 	while (mb != NULL)
 		mb = m_free(mb);
 }
 /*
  * __Userspace__
  * clean mbufs with M_EXT storage attached to them
  * if the reference count hits 1.
  */
 void
 mb_free_ext(struct mbuf *m)
 {
 	int skipmbuf;
 	KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
 	KASSERT(m->m_ext.ref_cnt != NULL, ("%s: ref_cnt not set", __func__));
 	/*
 	 * check if the header is embedded in the cluster
 	 */
 	skipmbuf = (m->m_flags & M_NOFREE);
 	/* Free the external attached storage if this
 	 * mbuf is the only reference to it.
 	 *__Userspace__ TODO: jumbo frames
 	 *
 	*/
 	/* NOTE: We had the same code that SCTP_DECREMENT_AND_CHECK_REFCOUNT
 	         reduces to here before but the IPHONE malloc commit had changed
 	         this to compare to 0 instead of 1 (see next line).  Why?
 	        . .. this caused a huge memory leak in Linux.
 	*/
 #ifdef IPHONE
 	if (atomic_fetchadd_int(m->m_ext.ref_cnt, -1) == 0)
 #else
 	if (SCTP_DECREMENT_AND_CHECK_REFCOUNT(m->m_ext.ref_cnt))
 #endif
 	{
 		if (m->m_ext.ext_type == EXT_CLUSTER){
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 			mb_dtor_clust(m->m_ext.ext_buf, &clust_mb_args);
 #endif
 			SCTP_ZONE_FREE(zone_clust, m->m_ext.ext_buf);
 			SCTP_ZONE_FREE(zone_ext_refcnt, (u_int*)m->m_ext.ref_cnt);
 			m->m_ext.ref_cnt = NULL;
 		}
 	}
 	if (skipmbuf)
 		return;
 	/* __Userspace__ Also freeing the storage for ref_cnt
 	 * Free this mbuf back to the mbuf zone with all m_ext
 	 * information purged.
 	 */
 	m->m_ext.ext_buf = NULL;
 	m->m_ext.ext_free = NULL;
 	m->m_ext.ext_args = NULL;
 	m->m_ext.ref_cnt = NULL;
 	m->m_ext.ext_size = 0;
 	m->m_ext.ext_type = 0;
 	m->m_flags &= ~M_EXT;
 #if defined(SCTP_SIMPLE_ALLOCATOR)
 	mb_dtor_mbuf(m, NULL);
 #endif
 	SCTP_ZONE_FREE(zone_mbuf, m);
 	/*umem_cache_free(zone_mbuf, m);*/
 }
 /*
  * "Move" mbuf pkthdr from "from" to "to".
  * "from" must have M_PKTHDR set, and "to" must be empty.
  */
 void
 m_move_pkthdr(struct mbuf *to, struct mbuf *from)
 {
 	to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
 	if ((to->m_flags & M_EXT) == 0)
 		to->m_data = to->m_pktdat;
 	to->m_pkthdr = from->m_pkthdr;		/* especially tags */
 	SLIST_INIT(&from->m_pkthdr.tags);	/* purge tags from src */
 	from->m_flags &= ~M_PKTHDR;
 }
 /*
  * Rearange an mbuf chain so that len bytes are contiguous
  * and in the data area of an mbuf (so that mtod and dtom
  * will work for a structure of size len).  Returns the resulting
  * mbuf chain on success, frees it and returns null on failure.
  * If there is room, it will add up to max_protohdr-len extra bytes to the
  * contiguous region in an attempt to avoid being called next time.
  */
 struct mbuf *
 m_pullup(struct mbuf *n, int len)
 {
 	struct mbuf *m;
 	int count;
 	int space;
 	/*
 	 * If first mbuf has no cluster, and has room for len bytes
 	 * without shifting current data, pullup into it,
 	 * otherwise allocate a new mbuf to prepend to the chain.
 	 */
 	if ((n->m_flags & M_EXT) == 0 &&
 	    n->m_data + len < &n->m_dat[MLEN] && n->m_next) {
 		if (n->m_len >= len)
 			return (n);
 		m = n;
 		n = n->m_next;
 		len -= m->m_len;
 	} else {
 		if (len > MHLEN)
 			goto bad;
 		MGET(m, M_NOWAIT, n->m_type);
 		if (m == NULL)
 			goto bad;
 		m->m_len = 0;
 		if (n->m_flags & M_PKTHDR)
 			M_MOVE_PKTHDR(m, n);
 	}
 	space = &m->m_dat[MLEN] - (m->m_data + m->m_len);
 	do {
 		count = min(min(max(len, max_protohdr), space), n->m_len);
 		bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len,
 		  (u_int)count);
 		len -= count;
 		m->m_len += count;
 		n->m_len -= count;
 		space -= count;
 		if (n->m_len)
 			n->m_data += count;
 		else
 			n = m_free(n);
 	} while (len > 0 && n);
 	if (len > 0) {
 		(void) m_free(m);
 		goto bad;
 	}
 	m->m_next = n;
 	return (m);
 bad:
 	m_freem(n);
 	mbstat.m_mpfail++;	/* XXX: No consistency. */
 	return (NULL);
 }
 static struct mbuf *
 m_dup1(struct mbuf *m, int off, int len, int wait)
 {
 	struct mbuf *n = NULL;
 	int copyhdr;
 	if (len > MCLBYTES)
 		return NULL;
 	if (off == 0 && (m->m_flags & M_PKTHDR) != 0)
 		copyhdr = 1;
 	else
 		copyhdr = 0;
 	if (len >= MINCLSIZE) {
 		if (copyhdr == 1) {
 			m_clget(n, wait); /* TODO: include code for copying the header */
 			m_dup_pkthdr(n, m, wait);
 		} else
 			m_clget(n, wait);
 	} else {
 		if (copyhdr == 1)
 			n = m_gethdr(wait, m->m_type);
 		else
 			n = m_get(wait, m->m_type);
 	}
 	if (!n)
 		return NULL; /* ENOBUFS */
 	if (copyhdr && !m_dup_pkthdr(n, m, wait)) {
 		m_free(n);
 		return NULL;
 	}
 	m_copydata(m, off, len, mtod(n, caddr_t));
 	n->m_len = len;
 	return n;
 }
 /* Taken from sys/kern/uipc_mbuf2.c */
 struct mbuf *
 m_pulldown(struct mbuf *m, int off, int len, int *offp)
 {
 	struct mbuf *n, *o;
 	int hlen, tlen, olen;
 	int writable;
 	/* check invalid arguments. */
 	KASSERT(m, ("m == NULL in m_pulldown()"));
 	if (len > MCLBYTES) {
 		m_freem(m);
 		return NULL;    /* impossible */
 	}
 #ifdef PULLDOWN_DEBUG
 	{
 		struct mbuf *t;
 		SCTP_DEBUG_USR(SCTP_DEBUG_USR, "before:");
 		for (t = m; t; t = t->m_next)
 			SCTP_DEBUG_USR(SCTP_DEBUG_USR, " %d", t->m_len);
 		SCTP_DEBUG_USR(SCTP_DEBUG_USR, "\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 */
 	}
 	writable = 0;
 	if ((n->m_flags & M_EXT) == 0 ||
 	    (n->m_ext.ext_type == EXT_CLUSTER && M_WRITABLE(n)))
 		writable = 1;
 	/*
 	 * 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 && writable)
 		goto ok;
 	/*
 	 * 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_dup1(n, off, n->m_len - off, M_NOWAIT);
 		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 ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen
 	    && writable) {
 		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
 	    && writable) {
 		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 (len > MLEN)
 		m_clget(o, M_NOWAIT);
 		/* o = m_getcl(M_NOWAIT, m->m_type, 0);*/
 	else
 		o = m_get(M_NOWAIT, m->m_type);
 	if (!o) {
 		m_freem(m);
 		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;
 		SCTP_DEBUG_USR(SCTP_DEBUG_USR, "after:");
 		for (t = m; t; t = t->m_next)
 			SCTP_DEBUG_USR(SCTP_DEBUG_USR, "%c%d", t == n ? '*' : ' ', t->m_len);
 		SCTP_DEBUG_USR(SCTP_DEBUG_USR, " (off=%d)\n", off);
 	}
 #endif
 	if (offp)
 		*offp = off;
 	return n;
 }
 /*
  * Attach the the cluster from *m to *n, set up m_ext in *n
  * and bump the refcount of the cluster.
  */
 static void
 mb_dupcl(struct mbuf *n, struct mbuf *m)
 {
 	KASSERT((m->m_flags & M_EXT) == M_EXT, ("%s: M_EXT not set", __func__));
 	KASSERT(m->m_ext.ref_cnt != NULL, ("%s: ref_cnt not set", __func__));
 	KASSERT((n->m_flags & M_EXT) == 0, ("%s: M_EXT set", __func__));
 	if (*(m->m_ext.ref_cnt) == 1)
 		*(m->m_ext.ref_cnt) += 1;
 	else
 		atomic_add_int(m->m_ext.ref_cnt, 1);
 	n->m_ext.ext_buf = m->m_ext.ext_buf;
 	n->m_ext.ext_free = m->m_ext.ext_free;
 	n->m_ext.ext_args = m->m_ext.ext_args;
 	n->m_ext.ext_size = m->m_ext.ext_size;
 	n->m_ext.ref_cnt = m->m_ext.ref_cnt;
 	n->m_ext.ext_type = m->m_ext.ext_type;
 	n->m_flags |= M_EXT;
 }
 /*
  * Make a copy of an mbuf chain starting "off0" bytes from the beginning,
  * continuing for "len" bytes.  If len is M_COPYALL, copy to end of mbuf.
  * The wait parameter is a choice of M_TRYWAIT/M_NOWAIT from caller.
  * Note that the copy is read-only, because clusters are not copied,
  * only their reference counts are incremented.
  */
 struct mbuf *
 m_copym(struct mbuf *m, int off0, int len, int wait)
 {
 	struct mbuf *n, **np;
 	int off = off0;
 	struct mbuf *top;
 	int copyhdr = 0;
 	KASSERT(off >= 0, ("m_copym, negative off %d", off));
 	KASSERT(len >= 0, ("m_copym, negative len %d", len));
 	if (off == 0 && m->m_flags & M_PKTHDR)
 		copyhdr = 1;
 	while (off > 0) {
 		KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain"));
 		if (off < m->m_len)
 			break;
 		off -= m->m_len;
 		m = m->m_next;
 	}
 	np = &top;
 	top = 0;
 	while (len > 0) {
 		if (m == NULL) {
 			KASSERT(len == M_COPYALL, ("m_copym, length > size of mbuf chain"));
 			break;
 		}
 		if (copyhdr)
 			MGETHDR(n, wait, m->m_type);
 		else
 			MGET(n, wait, m->m_type);
 		*np = n;
 		if (n == NULL)
 			goto nospace;
 		if (copyhdr) {
 			if (!m_dup_pkthdr(n, m, wait))
 				goto nospace;
 			if (len == M_COPYALL)
 				n->m_pkthdr.len -= off0;
 			else
 				n->m_pkthdr.len = len;
 			copyhdr = 0;
 		}
 		n->m_len = min(len, m->m_len - off);
 		if (m->m_flags & M_EXT) {
 			n->m_data = m->m_data + off;
 			mb_dupcl(n, m);
 		} else
 			bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t),
 			    (u_int)n->m_len);
 		if (len != M_COPYALL)
 			len -= n->m_len;
 		off = 0;
 		m = m->m_next;
 		np = &n->m_next;
 	}
 	if (top == NULL)
             mbstat.m_mcfail++;	/* XXX: No consistency. */
 	return (top);
 nospace:
 	m_freem(top);
 	mbstat.m_mcfail++;	/* XXX: No consistency. */
 	return (NULL);
 }
 int
 m_tag_copy_chain(struct mbuf *to, struct mbuf *from, int how)
 {
 	struct m_tag *p, *t, *tprev = NULL;
 	KASSERT(to && from, ("m_tag_copy_chain: null argument, to %p from %p", (void *)to, (void *)from));
 	m_tag_delete_chain(to, NULL);
 	SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
 		t = m_tag_copy(p, how);
 		if (t == NULL) {
 			m_tag_delete_chain(to, NULL);
 			return 0;
 		}
 		if (tprev == NULL)
 			SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
 		else
 			SLIST_INSERT_AFTER(tprev, t, m_tag_link);
 		tprev = t;
 	}
 	return 1;
 }
 /*
  * Duplicate "from"'s mbuf pkthdr in "to".
  * "from" must have M_PKTHDR set, and "to" must be empty.
  * In particular, this does a deep copy of the packet tags.
  */
 int
 m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how)
 {
 	to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT);
 	if ((to->m_flags & M_EXT) == 0)
 		to->m_data = to->m_pktdat;
 	to->m_pkthdr = from->m_pkthdr;
 	SLIST_INIT(&to->m_pkthdr.tags);
 	return (m_tag_copy_chain(to, from, MBTOM(how)));
 }
 /* Copy a single tag. */
 struct m_tag *
 m_tag_copy(struct m_tag *t, int how)
 {
 	struct m_tag *p;
 	KASSERT(t, ("m_tag_copy: null tag"));
 	p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
 	if (p == NULL)
 		return (NULL);
 	bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
 	return p;
 }
 /* Get a packet tag structure along with specified data following. */
 struct m_tag *
 m_tag_alloc(u_int32_t cookie, int type, int len, int wait)
 {
 	struct m_tag *t;
 	if (len < 0)
 		return NULL;
 	t = malloc(len + sizeof(struct m_tag));
 	if (t == NULL)
 		return NULL;
 	m_tag_setup(t, cookie, type, len);
 	t->m_tag_free = m_tag_free_default;
 	return t;
 }
 /* Free a packet tag. */
 void
 m_tag_free_default(struct m_tag *t)
 {
   free(t);
 }
 /*
  * Copy data from a buffer back into the indicated mbuf chain,
  * starting "off" bytes from the beginning, extending the mbuf
  * chain if necessary.
  */
 void
 m_copyback(struct mbuf *m0, int off, int len, caddr_t cp)
 {
 	int mlen;
 	struct mbuf *m = m0, *n;
 	int totlen = 0;
 	if (m0 == NULL)
 		return;
 	while (off > (mlen = m->m_len)) {
 		off -= mlen;
 		totlen += mlen;
 		if (m->m_next == NULL) {
 			n = m_get(M_NOWAIT, m->m_type);
 			if (n == NULL)
 				goto out;
 			bzero(mtod(n, caddr_t), MLEN);
 			n->m_len = min(MLEN, len + off);
 			m->m_next = n;
 		}
 		m = m->m_next;
 	}
 	while (len > 0) {
 		mlen = min (m->m_len - off, len);
 		bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen);
 		cp += mlen;
 		len -= mlen;
 		mlen += off;
 		off = 0;
 		totlen += mlen;
 		if (len == 0)
 			break;
 		if (m->m_next == NULL) {
 			n = m_get(M_NOWAIT, m->m_type);
 			if (n == NULL)
 				break;
 			n->m_len = min(MLEN, len);
 			m->m_next = n;
 		}
 		m = m->m_next;
 	}
 out:	if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen))
 		m->m_pkthdr.len = totlen;
 }
 /*
  * Lesser-used path for M_PREPEND:
  * allocate new mbuf to prepend to chain,
  * copy junk along.
  */
 struct mbuf *
 m_prepend(struct mbuf *m, int len, int how)
 {
 	struct mbuf *mn;
 	if (m->m_flags & M_PKTHDR)
 		MGETHDR(mn, how, m->m_type);
 	else
 		MGET(mn, how, m->m_type);
 	if (mn == NULL) {
 		m_freem(m);
 		return (NULL);
 	}
 	if (m->m_flags & M_PKTHDR)
 		M_MOVE_PKTHDR(mn, m);
 	mn->m_next = m;
 	m = mn;
 	if(m->m_flags & M_PKTHDR) {
 		if (len < MHLEN)
 			MH_ALIGN(m, len);
 	} else {
 		if (len < MLEN)
 			M_ALIGN(m, len);
 	}
 	m->m_len = len;
 	return (m);
 }
 /*
  * Copy data from an mbuf chain starting "off" bytes from the beginning,
  * continuing for "len" bytes, into the indicated buffer.
  */
 void
 m_copydata(const struct mbuf *m, int off, int len, caddr_t cp)
 {
 	u_int count;
 	KASSERT(off >= 0, ("m_copydata, negative off %d", off));
 	KASSERT(len >= 0, ("m_copydata, negative len %d", len));
 	while (off > 0) {
 		KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain"));
 		if (off < m->m_len)
 			break;
 		off -= m->m_len;
 		m = m->m_next;
 	}
 	while (len > 0) {
 		KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain"));
 		count = min(m->m_len - off, len);
 		bcopy(mtod(m, caddr_t) + off, cp, count);
 		len -= count;
 		cp += count;
 		off = 0;
 		m = m->m_next;
 	}
 }
 /*
  * Concatenate mbuf chain n to m.
  * Both chains must be of the same type (e.g. MT_DATA).
  * Any m_pkthdr is not updated.
  */
 void
 m_cat(struct mbuf *m, struct mbuf *n)
 {
 	while (m->m_next)
 		m = m->m_next;
 	while (n) {
 		if (m->m_flags & M_EXT ||
 		    m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) {
 			/* just join the two chains */
 			m->m_next = n;
 			return;
 		}
 		/* splat the data from one into the other */
 		bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, (u_int)n->m_len);
 		m->m_len += n->m_len;
 		n = m_free(n);
 	}
 }
 void
 m_adj(struct mbuf *mp, int req_len)
 {
 	int len = req_len;
 	struct mbuf *m;
 	int count;
 	if ((m = mp) == NULL)
 		return;
 	if (len >= 0) {
 		/*
 		 * Trim from head.
 		 */
 		while (m != NULL && len > 0) {
 			if (m->m_len <= len) {
 				len -= m->m_len;
 				m->m_len = 0;
 				m = m->m_next;
 			} else {
 				m->m_len -= len;
 				m->m_data += len;
 				len = 0;
 			}
 		}
 		m = mp;
 		if (mp->m_flags & M_PKTHDR)
 			m->m_pkthdr.len -= (req_len - len);
 	} else {
 		/*
 		 * Trim from tail.  Scan the mbuf chain,
 		 * calculating its length and finding the last mbuf.
 		 * If the adjustment only affects this mbuf, then just
 		 * adjust and return.  Otherwise, rescan and truncate
 		 * after the remaining size.
 		 */
 		len = -len;
 		count = 0;
 		for (;;) {
 			count += m->m_len;
 			if (m->m_next == (struct mbuf *)0)
 				break;
 			m = m->m_next;
 		}
 		if (m->m_len >= len) {
 			m->m_len -= len;
 			if (mp->m_flags & M_PKTHDR)
 				mp->m_pkthdr.len -= len;
 			return;
 		}
 		count -= len;
 		if (count < 0)
 			count = 0;
 		/*
 		 * Correct length for chain is "count".
 		 * Find the mbuf with last data, adjust its length,
 		 * and toss data from remaining mbufs on chain.
 		 */
 		m = mp;
 		if (m->m_flags & M_PKTHDR)
 			m->m_pkthdr.len = count;
 		for (; m; m = m->m_next) {
 			if (m->m_len >= count) {
 				m->m_len = count;
 				if (m->m_next != NULL) {
 					m_freem(m->m_next);
 					m->m_next = NULL;
 				}
 				break;
 			}
 			count -= m->m_len;
 		}
 	}
 }
 /* m_split is used within sctp_handle_cookie_echo. */
 /*
  * Partition an mbuf chain in two pieces, returning the tail --
  * all but the first len0 bytes.  In case of failure, it returns NULL and
  * attempts to restore the chain to its original state.
  *
  * Note that the resulting mbufs might be read-only, because the new
  * mbuf can end up sharing an mbuf cluster with the original mbuf if
  * the "breaking point" happens to lie within a cluster mbuf. Use the
  * M_WRITABLE() macro to check for this case.
  */
 struct mbuf *
 m_split(struct mbuf *m0, int len0, int wait)
 {
 	struct mbuf *m, *n;
 	u_int len = len0, remain;
 	/* MBUF_CHECKSLEEP(wait); */
 	for (m = m0; m && (int)len > m->m_len; m = m->m_next)
 		len -= m->m_len;
 	if (m == NULL)
 		return (NULL);
 	remain = m->m_len - len;
 	if (m0->m_flags & M_PKTHDR) {
 		MGETHDR(n, wait, m0->m_type);
 		if (n == NULL)
 			return (NULL);
 		n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif;
 		n->m_pkthdr.len = m0->m_pkthdr.len - len0;
 		m0->m_pkthdr.len = len0;
 		if (m->m_flags & M_EXT)
 			goto extpacket;
 		if (remain > MHLEN) {
 			/* m can't be the lead packet */
 			MH_ALIGN(n, 0);
 			n->m_next = m_split(m, len, wait);
 			if (n->m_next == NULL) {
 				(void) m_free(n);
 				return (NULL);
 			} else {
 				n->m_len = 0;
 				return (n);
 			}
 		} else
 			MH_ALIGN(n, remain);
 	} else if (remain == 0) {
 		n = m->m_next;
 		m->m_next = NULL;
 		return (n);
 	} else {
 		MGET(n, wait, m->m_type);
 		if (n == NULL)
 			return (NULL);
 		M_ALIGN(n, remain);
 	}
 extpacket:
 	if (m->m_flags & M_EXT) {
 		n->m_data = m->m_data + len;
 		mb_dupcl(n, m);
 	} else {
 		bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain);
 	}
 	n->m_len = remain;
 	m->m_len = len;
 	n->m_next = m->m_next;
 	m->m_next = NULL;
 	return (n);
 }
 int
 pack_send_buffer(caddr_t buffer, struct mbuf* mb){
 	int count_to_copy;
 	int total_count_copied = 0;
 	int offset = 0;
 	do {
 		count_to_copy = mb->m_len;
 		bcopy(mtod(mb, caddr_t), buffer+offset, count_to_copy);
 		offset += count_to_copy;
 		total_count_copied += count_to_copy;
 		mb = mb->m_next;
 	} while(mb);
 	return (total_count_copied);
 }

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netwerk/sctp/src/user_mbuf.c@6474c204b198 (annotated)

netwerk/sctp/src/user_mbuf.c