Add m-esr52 at 52.6.0

1 files changed, 1431 insertions, 0 deletions

diff --git a/netwerk/sctp/src/user_mbuf.c b/netwerk/sctp/src/user_mbuf.c
new file mode 100755
index 000000000..de8f0fbc8
--- /dev/null
+++ b/netwerk/sctp/src/user_mbuf.c
@@ -0,0 +1,1431 @@
+/*-
+ * 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);
+}