453 lines
12 KiB
C
453 lines
12 KiB
C
/* $FreeBSD$ */
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/*
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* IPsec-specific mbuf routines.
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*/
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#include "opt_param.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/mbuf.h>
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#include <sys/socket.h>
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#include <net/route.h>
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#include <netinet/in.h>
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#include <netipsec/ipsec.h>
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extern struct mbuf *m_getptr(struct mbuf *, int, int *);
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/*
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* Create a writable copy of the mbuf chain. While doing this
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* we compact the chain with a goal of producing a chain with
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* at most two mbufs. The second mbuf in this chain is likely
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* to be a cluster. The primary purpose of this work is to create
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* a writable packet for encryption, compression, etc. The
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* secondary goal is to linearize the data so the data can be
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* passed to crypto hardware in the most efficient manner possible.
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*/
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struct mbuf *
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m_clone(struct mbuf *m0)
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{
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struct mbuf *m, *mprev;
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struct mbuf *n, *mfirst, *mlast;
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int len, off;
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KASSERT(m0 != NULL, ("m_clone: null mbuf"));
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mprev = NULL;
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for (m = m0; m != NULL; m = mprev->m_next) {
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/*
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* Regular mbufs are ignored unless there's a cluster
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* in front of it that we can use to coalesce. We do
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* the latter mainly so later clusters can be coalesced
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* also w/o having to handle them specially (i.e. convert
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* mbuf+cluster -> cluster). This optimization is heavily
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* influenced by the assumption that we're running over
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* Ethernet where MCLBYTES is large enough that the max
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* packet size will permit lots of coalescing into a
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* single cluster. This in turn permits efficient
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* crypto operations, especially when using hardware.
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*/
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if ((m->m_flags & M_EXT) == 0) {
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if (mprev && (mprev->m_flags & M_EXT) &&
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m->m_len <= M_TRAILINGSPACE(mprev)) {
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/* XXX: this ignores mbuf types */
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memcpy(mtod(mprev, caddr_t) + mprev->m_len,
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mtod(m, caddr_t), m->m_len);
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mprev->m_len += m->m_len;
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mprev->m_next = m->m_next; /* unlink from chain */
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m_free(m); /* reclaim mbuf */
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newipsecstat.ips_mbcoalesced++;
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} else {
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mprev = m;
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}
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continue;
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}
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/*
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* Writable mbufs are left alone (for now).
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*/
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if (!MEXT_IS_REF(m)) {
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mprev = m;
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continue;
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}
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/*
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* Not writable, replace with a copy or coalesce with
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* the previous mbuf if possible (since we have to copy
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* it anyway, we try to reduce the number of mbufs and
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* clusters so that future work is easier).
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*/
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KASSERT(m->m_flags & M_EXT,
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("m_clone: m_flags 0x%x", m->m_flags));
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/* NB: we only coalesce into a cluster or larger */
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if (mprev != NULL && (mprev->m_flags & M_EXT) &&
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m->m_len <= M_TRAILINGSPACE(mprev)) {
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/* XXX: this ignores mbuf types */
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memcpy(mtod(mprev, caddr_t) + mprev->m_len,
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mtod(m, caddr_t), m->m_len);
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mprev->m_len += m->m_len;
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mprev->m_next = m->m_next; /* unlink from chain */
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m_free(m); /* reclaim mbuf */
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newipsecstat.ips_clcoalesced++;
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continue;
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}
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/*
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* Allocate new space to hold the copy...
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*/
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/* XXX why can M_PKTHDR be set past the first mbuf? */
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if (mprev == NULL && (m->m_flags & M_PKTHDR)) {
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/*
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* NB: if a packet header is present we must
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* allocate the mbuf separately from any cluster
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* because M_MOVE_PKTHDR will smash the data
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* pointer and drop the M_EXT marker.
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*/
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MGETHDR(n, M_DONTWAIT, m->m_type);
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if (n == NULL) {
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m_freem(m0);
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return (NULL);
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}
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M_MOVE_PKTHDR(n, m);
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MCLGET(n, M_DONTWAIT);
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if ((n->m_flags & M_EXT) == 0) {
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m_free(n);
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m_freem(m0);
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return (NULL);
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}
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} else {
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n = m_getcl(M_DONTWAIT, m->m_type, m->m_flags);
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if (n == NULL) {
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m_freem(m0);
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return (NULL);
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}
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}
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/*
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* ... and copy the data. We deal with jumbo mbufs
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* (i.e. m_len > MCLBYTES) by splitting them into
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* clusters. We could just malloc a buffer and make
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* it external but too many device drivers don't know
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* how to break up the non-contiguous memory when
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* doing DMA.
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*/
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len = m->m_len;
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off = 0;
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mfirst = n;
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mlast = NULL;
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for (;;) {
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int cc = min(len, MCLBYTES);
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memcpy(mtod(n, caddr_t), mtod(m, caddr_t) + off, cc);
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n->m_len = cc;
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if (mlast != NULL)
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mlast->m_next = n;
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mlast = n;
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newipsecstat.ips_clcopied++;
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len -= cc;
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if (len <= 0)
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break;
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off += cc;
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n = m_getcl(M_DONTWAIT, m->m_type, m->m_flags);
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if (n == NULL) {
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m_freem(mfirst);
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m_freem(m0);
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return (NULL);
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}
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}
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n->m_next = m->m_next;
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if (mprev == NULL)
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m0 = mfirst; /* new head of chain */
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else
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mprev->m_next = mfirst; /* replace old mbuf */
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m_free(m); /* release old mbuf */
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mprev = mfirst;
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}
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return (m0);
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}
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/*
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* Make space for a new header of length hlen at skip bytes
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* into the packet. When doing this we allocate new mbufs only
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* when absolutely necessary. The mbuf where the new header
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* is to go is returned together with an offset into the mbuf.
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* If NULL is returned then the mbuf chain may have been modified;
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* the caller is assumed to always free the chain.
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*/
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struct mbuf *
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m_makespace(struct mbuf *m0, int skip, int hlen, int *off)
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{
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struct mbuf *m;
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unsigned remain;
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KASSERT(m0 != NULL, ("m_dmakespace: null mbuf"));
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KASSERT(hlen < MHLEN, ("m_makespace: hlen too big: %u", hlen));
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for (m = m0; m && skip > m->m_len; m = m->m_next)
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skip -= m->m_len;
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if (m == NULL)
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return (NULL);
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/*
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* At this point skip is the offset into the mbuf m
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* where the new header should be placed. Figure out
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* if there's space to insert the new header. If so,
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* and copying the remainder makese sense then do so.
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* Otherwise insert a new mbuf in the chain, splitting
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* the contents of m as needed.
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*/
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remain = m->m_len - skip; /* data to move */
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if (hlen > M_TRAILINGSPACE(m)) {
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struct mbuf *n;
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/* XXX code doesn't handle clusters XXX */
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KASSERT(remain < MLEN,
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("m_makespace: remainder too big: %u", remain));
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/*
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* Not enough space in m, split the contents
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* of m, inserting new mbufs as required.
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*
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* NB: this ignores mbuf types.
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*/
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MGET(n, M_DONTWAIT, MT_DATA);
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if (n == NULL)
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return (NULL);
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n->m_next = m->m_next; /* splice new mbuf */
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m->m_next = n;
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newipsecstat.ips_mbinserted++;
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if (hlen <= M_TRAILINGSPACE(m) + remain) {
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/*
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* New header fits in the old mbuf if we copy
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* the remainder; just do the copy to the new
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* mbuf and we're good to go.
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*/
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memcpy(mtod(n, caddr_t),
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mtod(m, caddr_t) + skip, remain);
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n->m_len = remain;
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m->m_len = skip + hlen;
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*off = skip;
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} else {
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/*
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* No space in the old mbuf for the new header.
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* Make space in the new mbuf and check the
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* remainder'd data fits too. If not then we
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* must allocate an additional mbuf (yech).
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*/
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n->m_len = 0;
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if (remain + hlen > M_TRAILINGSPACE(n)) {
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struct mbuf *n2;
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MGET(n2, M_DONTWAIT, MT_DATA);
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/* NB: new mbuf is on chain, let caller free */
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if (n2 == NULL)
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return (NULL);
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n2->m_len = 0;
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memcpy(mtod(n2, caddr_t),
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mtod(m, caddr_t) + skip, remain);
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n2->m_len = remain;
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/* splice in second mbuf */
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n2->m_next = n->m_next;
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n->m_next = n2;
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newipsecstat.ips_mbinserted++;
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} else {
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memcpy(mtod(n, caddr_t) + hlen,
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mtod(m, caddr_t) + skip, remain);
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n->m_len += remain;
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}
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m->m_len -= remain;
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n->m_len += hlen;
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m = n; /* header is at front ... */
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*off = 0; /* ... of new mbuf */
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}
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} else {
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/*
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* Copy the remainder to the back of the mbuf
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* so there's space to write the new header.
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*/
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/* XXX can this be memcpy? does it handle overlap? */
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ovbcopy(mtod(m, caddr_t) + skip,
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mtod(m, caddr_t) + skip + hlen, remain);
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m->m_len += hlen;
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*off = skip;
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}
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m0->m_pkthdr.len += hlen; /* adjust packet length */
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return m;
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}
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/*
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* m_pad(m, n) pads <m> with <n> bytes at the end. The packet header
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* length is updated, and a pointer to the first byte of the padding
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* (which is guaranteed to be all in one mbuf) is returned.
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*/
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caddr_t
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m_pad(struct mbuf *m, int n)
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{
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register struct mbuf *m0, *m1;
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register int len, pad;
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caddr_t retval;
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if (n <= 0) { /* No stupid arguments. */
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DPRINTF(("m_pad: pad length invalid (%d)\n", n));
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m_freem(m);
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return NULL;
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}
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len = m->m_pkthdr.len;
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pad = n;
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m0 = m;
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while (m0->m_len < len) {
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KASSERT(m0->m_next != NULL, ("m_pad: m0 null, len %u m_len %u", len, m0->m_len));/*XXX*/
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len -= m0->m_len;
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m0 = m0->m_next;
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}
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if (m0->m_len != len) {
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DPRINTF(("m_pad: length mismatch (should be %d instead of %d)\n",
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m->m_pkthdr.len, m->m_pkthdr.len + m0->m_len - len));
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m_freem(m);
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return NULL;
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}
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/* Check for zero-length trailing mbufs, and find the last one. */
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for (m1 = m0; m1->m_next; m1 = m1->m_next) {
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if (m1->m_next->m_len != 0) {
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DPRINTF(("m_pad: length mismatch (should be %d "
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"instead of %d)\n",
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m->m_pkthdr.len,
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m->m_pkthdr.len + m1->m_next->m_len));
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m_freem(m);
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return NULL;
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}
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m0 = m1->m_next;
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}
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if (pad > M_TRAILINGSPACE(m0)) {
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/* Add an mbuf to the chain. */
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MGET(m1, M_DONTWAIT, MT_DATA);
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if (m1 == 0) {
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m_freem(m0);
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DPRINTF(("m_pad: unable to get extra mbuf\n"));
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return NULL;
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}
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m0->m_next = m1;
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m0 = m1;
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m0->m_len = 0;
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}
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retval = m0->m_data + m0->m_len;
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m0->m_len += pad;
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m->m_pkthdr.len += pad;
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return retval;
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}
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/*
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* Remove hlen data at offset skip in the packet. This is used by
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* the protocols strip protocol headers and associated data (e.g. IV,
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* authenticator) on input.
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*/
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int
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m_striphdr(struct mbuf *m, int skip, int hlen)
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{
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struct mbuf *m1;
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int roff;
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/* Find beginning of header */
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m1 = m_getptr(m, skip, &roff);
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if (m1 == NULL)
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return (EINVAL);
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/* Remove the header and associated data from the mbuf. */
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if (roff == 0) {
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/* The header was at the beginning of the mbuf */
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newipsecstat.ips_input_front++;
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m_adj(m1, hlen);
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if ((m1->m_flags & M_PKTHDR) == 0)
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m->m_pkthdr.len -= hlen;
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} else if (roff + hlen >= m1->m_len) {
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struct mbuf *mo;
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/*
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* Part or all of the header is at the end of this mbuf,
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* so first let's remove the remainder of the header from
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* the beginning of the remainder of the mbuf chain, if any.
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*/
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newipsecstat.ips_input_end++;
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if (roff + hlen > m1->m_len) {
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/* Adjust the next mbuf by the remainder */
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m_adj(m1->m_next, roff + hlen - m1->m_len);
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/* The second mbuf is guaranteed not to have a pkthdr... */
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m->m_pkthdr.len -= (roff + hlen - m1->m_len);
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}
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/* Now, let's unlink the mbuf chain for a second...*/
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mo = m1->m_next;
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m1->m_next = NULL;
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/* ...and trim the end of the first part of the chain...sick */
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m_adj(m1, -(m1->m_len - roff));
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if ((m1->m_flags & M_PKTHDR) == 0)
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m->m_pkthdr.len -= (m1->m_len - roff);
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/* Finally, let's relink */
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m1->m_next = mo;
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} else {
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/*
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* The header lies in the "middle" of the mbuf; copy
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* the remainder of the mbuf down over the header.
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*/
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newipsecstat.ips_input_middle++;
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bcopy(mtod(m1, u_char *) + roff + hlen,
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mtod(m1, u_char *) + roff,
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m1->m_len - (roff + hlen));
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m1->m_len -= hlen;
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m->m_pkthdr.len -= hlen;
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}
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return (0);
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}
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/*
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* Diagnostic routine to check mbuf alignment as required by the
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* crypto device drivers (that use DMA).
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*/
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void
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m_checkalignment(const char* where, struct mbuf *m0, int off, int len)
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{
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int roff;
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struct mbuf *m = m_getptr(m0, off, &roff);
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caddr_t addr;
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if (m == NULL)
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return;
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printf("%s (off %u len %u): ", where, off, len);
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addr = mtod(m, caddr_t) + roff;
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do {
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int mlen;
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if (((uintptr_t) addr) & 3) {
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printf("addr misaligned %p,", addr);
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break;
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}
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mlen = m->m_len;
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if (mlen > len)
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mlen = len;
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len -= mlen;
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if (len && (mlen & 3)) {
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printf("len mismatch %u,", mlen);
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break;
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}
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m = m->m_next;
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addr = m ? mtod(m, caddr_t) : NULL;
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} while (m && len > 0);
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for (m = m0; m; m = m->m_next)
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printf(" [%p:%u]", mtod(m, caddr_t), m->m_len);
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printf("\n");
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}
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