Introduce API for sequential reads/writes (build/dissect) of mbuf chains.

Reviewed by:	Ian Dowse <iedowse@maths.tcd.ie>,
		Bosko Milekic <bmilekic@technokratis.com>,
		Julian Elischer <julian@elischer.org> and arch@/net@
Obtained from:	smbfs

sys/conf/NOTES

@@ -413,6 +413,9 @@ options 	NETATALKDEBUG		#Appletalk debugging
 #options 	NS			#Xerox NS protocols
 #options 	NSIP			#XNS over IP
 
+# mchain library. It can be either loaded as KLD or compiled into kernel
+options 	LIBMCHAIN
+
 # netgraph(4). Enable the base netgraph code with the NETGRAPH option.
 # Individual node types can be enabled with the corresponding option
 # listed below; however, this is not strictly necessary as netgraph

sys/conf/files

@@ -697,6 +697,7 @@ kern/subr_diskslice.c	standard
 kern/subr_eventhandler.c	standard
 kern/subr_kobj.c	standard
 kern/subr_log.c		standard
+kern/subr_mchain.c	optional libmchain
 kern/subr_module.c	standard
 kern/subr_prf.c		standard
 kern/subr_prof.c	standard

sys/conf/options

@@ -262,6 +262,7 @@ IPSTEALTH
 IPX			opt_ipx.h
 IPXIP			opt_ipx.h
 IPTUNNEL		opt_ipx.h
+LIBMCHAIN
 NCP			opt_ncp.h
 NETATALK		opt_atalk.h
 PPP_BSDCOMP		opt_ppp.h

sys/i386/conf/NOTES

@@ -413,6 +413,9 @@ options 	NETATALKDEBUG		#Appletalk debugging
 #options 	NS			#Xerox NS protocols
 #options 	NSIP			#XNS over IP
 
+# mchain library. It can be either loaded as KLD or compiled into kernel
+options 	LIBMCHAIN
+
 # netgraph(4). Enable the base netgraph code with the NETGRAPH option.
 # Individual node types can be enabled with the corresponding option
 # listed below; however, this is not strictly necessary as netgraph

sys/kern/subr_mchain.c

@@ -0,0 +1,549 @@
+/*
+ * Copyright (c) 2000, 2001 Boris Popov
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *    This product includes software developed by Boris Popov.
+ * 4. Neither the name of the author nor the names of any co-contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/errno.h>
+#include <sys/mbuf.h>
+#include <sys/module.h>
+#include <sys/uio.h>
+
+#include <sys/mchain.h>
+
+MODULE_VERSION(libmchain, 1);
+
+#define MBERROR(format, args...) printf("%s(%d): "format, __FUNCTION__ , \
+				    __LINE__ ,## args)
+
+#define MBPANIC(format, args...) printf("%s(%d): "format, __FUNCTION__ , \
+				    __LINE__ ,## args)
+
+/*
+ * Various helper functions
+ */
+int
+m_fixhdr(struct mbuf *m0)
+{
+	struct mbuf *m = m0;
+	int len = 0;
+
+	while (m) {
+		len += m->m_len;
+		m = m->m_next;
+	}
+	m0->m_pkthdr.len = len;
+	return len;
+}
+
+int
+mb_init(struct mbchain *mbp)
+{
+	struct mbuf *m;
+
+	m = m_gethdr(M_TRYWAIT, MT_DATA);
+	if (m == NULL) 
+		return ENOBUFS;
+	m->m_pkthdr.rcvif = NULL;
+	m->m_len = 0;
+	mb_initm(mbp, m);
+	return 0;
+}
+
+void
+mb_initm(struct mbchain *mbp, struct mbuf *m)
+{
+	bzero(mbp, sizeof(*mbp));
+	mbp->mb_top = mbp->mb_cur = m;
+	mbp->mb_mleft = M_TRAILINGSPACE(m);
+}
+
+void
+mb_done(struct mbchain *mbp)
+{
+	if (mbp->mb_top) {
+		m_freem(mbp->mb_top);
+		mbp->mb_top = NULL;
+	}
+}
+
+struct mbuf *
+mb_detach(struct mbchain *mbp)
+{
+	struct mbuf *m;
+
+	m = mbp->mb_top;
+	mbp->mb_top = NULL;
+	return m;
+}
+
+int
+mb_fixhdr(struct mbchain *mbp)
+{
+	return mbp->mb_top->m_pkthdr.len = m_fixhdr(mbp->mb_top);
+}
+
+/*
+ * Check if object of size 'size' fit to the current position and
+ * allocate new mbuf if not. Advance pointers and increase length of mbuf(s).
+ * Return pointer to the object placeholder or NULL if any error occured.
+ * Note: size should be <= MLEN 
+ */
+caddr_t
+mb_reserve(struct mbchain *mbp, int size)
+{
+	struct mbuf *m, *mn;
+	caddr_t bpos;
+
+	if (size > MLEN)
+		panic("mb_reserve: size = %d\n", size);
+	m = mbp->mb_cur;
+	if (mbp->mb_mleft < size) {
+		mn = m_get(M_TRYWAIT, MT_DATA);
+		if (mn == NULL)
+			return NULL;
+		mbp->mb_cur = m->m_next = mn;
+		m = mn;
+		m->m_len = 0;
+		mbp->mb_mleft = M_TRAILINGSPACE(m);
+	}
+	mbp->mb_mleft -= size;
+	mbp->mb_count += size;
+	bpos = mtod(m, caddr_t) + m->m_len;
+	m->m_len += size;
+	return bpos;
+}
+
+int
+mb_put_uint8(struct mbchain *mbp, u_int8_t x)
+{
+	return mb_put_mem(mbp, (caddr_t)&x, sizeof(x), MB_MSYSTEM);
+}
+
+int
+mb_put_uint16be(struct mbchain *mbp, u_int16_t x)
+{
+	x = htobes(x);
+	return mb_put_mem(mbp, (caddr_t)&x, sizeof(x), MB_MSYSTEM);
+}
+
+int
+mb_put_uint16le(struct mbchain *mbp, u_int16_t x)
+{
+	x = htoles(x);
+	return mb_put_mem(mbp, (caddr_t)&x, sizeof(x), MB_MSYSTEM);
+}
+
+int
+mb_put_uint32be(struct mbchain *mbp, u_int32_t x)
+{
+	x = htobel(x);
+	return mb_put_mem(mbp, (caddr_t)&x, sizeof(x), MB_MSYSTEM);
+}
+
+int
+mb_put_uint32le(struct mbchain *mbp, u_int32_t x)
+{
+	x = htolel(x);
+	return mb_put_mem(mbp, (caddr_t)&x, sizeof(x), MB_MSYSTEM);
+}
+
+int
+mb_put_int64be(struct mbchain *mbp, int64_t x)
+{
+	x = htobeq(x);
+	return mb_put_mem(mbp, (caddr_t)&x, sizeof(x), MB_MSYSTEM);
+}
+
+int
+mb_put_int64le(struct mbchain *mbp, int64_t x)
+{
+	x = htoleq(x);
+	return mb_put_mem(mbp, (caddr_t)&x, sizeof(x), MB_MSYSTEM);
+}
+
+int
+mb_put_mem(struct mbchain *mbp, c_caddr_t source, int size, int type)
+{
+	struct mbuf *m;
+	caddr_t dst;
+	c_caddr_t src;
+	int cplen, error, mleft, count;
+
+	m = mbp->mb_cur;
+	mleft = mbp->mb_mleft;
+
+	while (size > 0) {
+		if (mleft == 0) {
+			if (m->m_next == NULL) {
+				m = m_getm(m, size, M_TRYWAIT, MT_DATA);
+				if (m == NULL)
+					return ENOBUFS;
+			}
+			m = m->m_next;
+			mleft = M_TRAILINGSPACE(m);
+			continue;
+		}
+		cplen = mleft > size ? size : mleft;
+		dst = mtod(m, caddr_t) + m->m_len;
+		switch (type) {
+		    case MB_MCUSTOM:
+			error = mbp->mb_copy(mbp, source, dst, cplen);
+			if (error)
+				return error;
+			break;
+		    case MB_MINLINE:
+			for (src = source, count = cplen; count; count--)
+				*dst++ = *src++;
+			break;
+		    case MB_MSYSTEM:
+			bcopy(source, dst, cplen);
+			break;
+		    case MB_MUSER:
+			error = copyin(source, dst, cplen);
+			if (error)
+				return error;
+			break;
+		    case MB_MZERO:
+			bzero(dst, cplen);
+			break;
+		}
+		size -= cplen;
+		source += cplen;
+		m->m_len += cplen;
+		mleft -= cplen;
+		mbp->mb_count += cplen;
+	}
+	mbp->mb_cur = m;
+	mbp->mb_mleft = mleft;
+	return 0;
+}
+
+int
+mb_put_mbuf(struct mbchain *mbp, struct mbuf *m)
+{
+	mbp->mb_cur->m_next = m;
+	while (m) {
+		mbp->mb_count += m->m_len;
+		if (m->m_next == NULL)
+			break;
+		m = m->m_next;
+	}
+	mbp->mb_mleft = M_TRAILINGSPACE(m);
+	mbp->mb_cur = m;
+	return 0;
+}
+
+/*
+ * copies a uio scatter/gather list to an mbuf chain.
+ * NOTE: can ony handle iovcnt == 1
+ */
+int
+mb_put_uio(struct mbchain *mbp, struct uio *uiop, int size)
+{
+	long left;
+	int mtype, error;
+
+#ifdef DIAGNOSTIC
+	if (uiop->uio_iovcnt != 1)
+		MBPANIC("iovcnt != 1");
+#endif
+	mtype = (uiop->uio_segflg == UIO_SYSSPACE) ? MB_MSYSTEM : MB_MUSER;
+
+	while (size > 0) {
+		left = uiop->uio_iov->iov_len;
+		if (left > size)
+			left = size;
+		error = mb_put_mem(mbp, uiop->uio_iov->iov_base, left, mtype);
+		if (error)
+			return error;
+		uiop->uio_offset += left;
+		uiop->uio_resid -= left;
+		uiop->uio_iov->iov_base += left;
+		uiop->uio_iov->iov_len -= left;
+		size -= left;
+	}
+	return 0;
+}
+
+/*
+ * Routines for fetching data from an mbuf chain
+ */
+int
+md_init(struct mdchain *mdp)
+{
+	struct mbuf *m;
+
+	m = m_gethdr(M_TRYWAIT, MT_DATA);
+	if (m == NULL) 
+		return ENOBUFS;
+	m->m_pkthdr.rcvif = NULL;
+	m->m_len = 0;
+	md_initm(mdp, m);
+	return 0;
+}
+
+void
+md_initm(struct mdchain *mdp, struct mbuf *m)
+{
+	bzero(mdp, sizeof(*mdp));
+	mdp->md_top = mdp->md_cur = m;
+	mdp->md_pos = mtod(m, u_char*);
+}
+
+void
+md_done(struct mdchain *mdp)
+{
+	if (mdp->md_top) {
+		m_freem(mdp->md_top);
+		mdp->md_top = NULL;
+	}
+}
+
+/*
+ * Append a separate mbuf chain. It is caller responsibility to prevent
+ * multiple calls to fetch/record routines.
+ */
+void
+md_append_record(struct mdchain *mdp, struct mbuf *top)
+{
+	struct mbuf *m;
+
+	if (mdp->md_top == NULL) {
+		md_initm(mdp, top);
+		return;
+	}
+	m = mdp->md_top;
+	while (m->m_nextpkt)
+		m = m->m_nextpkt;
+	m->m_nextpkt = top;
+	top->m_nextpkt = NULL;
+	return;
+}
+
+/*
+ * Put next record in place of existing
+ */
+int
+md_next_record(struct mdchain *mdp)
+{
+	struct mbuf *m;
+
+	if (mdp->md_top == NULL)
+		return ENOENT;
+	m = mdp->md_top->m_nextpkt;
+	md_done(mdp);
+	if (m == NULL)
+		return ENOENT;
+	md_initm(mdp, m);
+	return 0;
+}
+
+int
+md_get_uint8(struct mdchain *mdp, u_int8_t *x)
+{
+	return md_get_mem(mdp, x, 1, MB_MINLINE);
+}
+
+int
+md_get_uint16(struct mdchain *mdp, u_int16_t *x)
+{
+	return md_get_mem(mdp, (caddr_t)x, 2, MB_MINLINE);
+}
+
+int
+md_get_uint16le(struct mdchain *mdp, u_int16_t *x)
+{
+	u_int16_t v;
+	int error = md_get_uint16(mdp, &v);
+
+	*x = letohs(v);
+	return error;
+}
+
+int
+md_get_uint16be(struct mdchain *mdp, u_int16_t *x) {
+	u_int16_t v;
+	int error = md_get_uint16(mdp, &v);
+
+	*x = betohs(v);
+	return error;
+}
+
+int
+md_get_uint32(struct mdchain *mdp, u_int32_t *x)
+{
+	return md_get_mem(mdp, (caddr_t)x, 4, MB_MINLINE);
+}
+
+int
+md_get_uint32be(struct mdchain *mdp, u_int32_t *x)
+{
+	u_int32_t v;
+	int error;
+
+	error = md_get_uint32(mdp, &v);
+	*x = betohl(v);
+	return error;
+}
+
+int
+md_get_uint32le(struct mdchain *mdp, u_int32_t *x)
+{
+	u_int32_t v;
+	int error;
+
+	error = md_get_uint32(mdp, &v);
+	*x = letohl(v);
+	return error;
+}
+
+int
+md_get_int64(struct mdchain *mdp, int64_t *x)
+{
+	return md_get_mem(mdp, (caddr_t)x, 8, MB_MINLINE);
+}
+
+int
+md_get_int64be(struct mdchain *mdp, int64_t *x)
+{
+	int64_t v;
+	int error;
+
+	error = md_get_int64(mdp, &v);
+	*x = betohq(v);
+	return error;
+}
+
+int
+md_get_int64le(struct mdchain *mdp, int64_t *x)
+{
+	int64_t v;
+	int error;
+
+	error = md_get_int64(mdp, &v);
+	*x = letohq(v);
+	return error;
+}
+
+int
+md_get_mem(struct mdchain *mdp, caddr_t target, int size, int type)
+{
+	struct mbuf *m = mdp->md_cur;
+	int error;
+	u_int count;
+	u_char *s;
+	
+	while (size > 0) {
+		if (m == NULL) {
+			MBERROR("incomplete copy\n");
+			return EBADRPC;
+		}
+		s = mdp->md_pos;
+		count = mtod(m, u_char*) + m->m_len - s;
+		if (count == 0) {
+			mdp->md_cur = m = m->m_next;
+			if (m)
+				s = mdp->md_pos = mtod(m, caddr_t);
+			continue;
+		}
+		if (count > size)
+			count = size;
+		size -= count;
+		mdp->md_pos += count;
+		if (target == NULL)
+			continue;
+		switch (type) {
+		    case MB_MUSER:
+			error = copyout(s, target, count);
+			if (error)
+				return error;
+			break;
+		    case MB_MSYSTEM:
+			bcopy(s, target, count);
+			break;
+		    case MB_MINLINE:
+			while (count--)
+				*target++ = *s++;
+			continue;
+		}
+		target += count;
+	}
+	return 0;
+}
+
+int
+md_get_mbuf(struct mdchain *mdp, int size, struct mbuf **ret)
+{
+	struct mbuf *m = mdp->md_cur, *rm;
+
+	rm = m_copym(m, mdp->md_pos - mtod(m, u_char*), size, M_TRYWAIT);
+	if (rm == NULL)
+		return EBADRPC;
+	md_get_mem(mdp, NULL, size, MB_MZERO);
+	*ret = rm;
+	return 0;
+}
+
+int
+md_get_uio(struct mdchain *mdp, struct uio *uiop, int size)
+{
+	char *uiocp;
+	long left;
+	int mtype, error;
+
+	mtype = (uiop->uio_segflg == UIO_SYSSPACE) ? MB_MSYSTEM : MB_MUSER;
+	while (size > 0) {
+		if (uiop->uio_iovcnt <= 0 || uiop->uio_iov == NULL)
+			return EFBIG;
+		left = uiop->uio_iov->iov_len;
+		uiocp = uiop->uio_iov->iov_base;
+		if (left > size)
+			left = size;
+		error = md_get_mem(mdp, uiocp, left, mtype);
+		if (error)
+			return error;
+		uiop->uio_offset += left;
+		uiop->uio_resid -= left;
+		if (uiop->uio_iov->iov_len <= size) {
+			uiop->uio_iovcnt--;
+			uiop->uio_iov++;
+		} else {
+			uiop->uio_iov->iov_base += left;
+			uiop->uio_iov->iov_len -= left;
+		}
+		size -= left;
+	}
+	return 0;
+}

sys/modules/Makefile

@@ -9,7 +9,7 @@ _random=	random
 SUBDIR=	3dfx accf_data accf_http agp aha amr an aue \
 	cam ccd cd9660 coda cue dc de ed fdesc fxp if_disc if_ef \
 	if_ppp if_sl if_tap if_tun ip6fw ipfilter ipfw ispfw joy kue \
-	linux lnc md mfs mii mlx msdos ncp netgraph nfs ntfs nullfs \
+	libmchain linux lnc md mfs mii mlx msdos ncp netgraph nfs ntfs nullfs \
 	nwfs pcn portal procfs ${_random}  \
 	rl rp sf sis sk sn sound sppp ste sym syscons sysvipc ti tl twe tx \
 	udbp ugen uhid ukbd ulpt umapfs umass umodem ums union urio usb \

sys/modules/libmchain/Makefile

@@ -0,0 +1,8 @@
+# $FreeBSD$
+
+.PATH: ${.CURDIR}/../../kern
+
+KMOD=	libmchain
+SRCS=	subr_mchain.c
+
+.include <bsd.kmod.mk>

sys/sys/mchain.h

@@ -0,0 +1,155 @@
+/*
+ * Copyright (c) 2000, 2001 Boris Popov
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *    This product includes software developed by Boris Popov.
+ * 4. Neither the name of the author nor the names of any co-contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+#ifndef _SYS_MCHAIN_H_
+#define _SYS_MCHAIN_H_
+
+#include <machine/endian.h>
+
+/*
+ * This macros probably belongs to the endian.h
+ */
+#if (BYTE_ORDER == LITTLE_ENDIAN)
+
+#define htoles(x)	((u_int16_t)(x))
+#define letohs(x)	((u_int16_t)(x))
+#define	htolel(x)	((u_int32_t)(x))
+#define	letohl(x)	((u_int32_t)(x))
+#define	htoleq(x)	((int64_t)(x))
+#define	letohq(x)	((int64_t)(x))
+
+#define htobes(x)	(htons(x))
+#define betohs(x)	(ntohs(x))
+#define htobel(x)	(htonl(x))
+#define betohl(x)	(ntohl(x))
+
+static __inline int64_t
+htobeq(int64_t x)
+{
+	return (int64_t)htonl((u_int32_t)(x >> 32)) |
+	    (int64_t)htonl((u_int32_t)(x & 0xffffffff)) << 32;
+}
+
+static __inline int64_t
+betohq(int64_t x)
+{
+	return (int64_t)ntohl((u_int32_t)(x >> 32)) |
+	    (int64_t)ntohl((u_int32_t)(x & 0xffffffff)) << 32;
+}
+
+#else	/* (BYTE_ORDER == LITTLE_ENDIAN) */
+
+#error "Macros for Big-Endians are incomplete"
+
+/*
+#define htoles(x)	((u_int16_t)(x))
+#define letohs(x)	((u_int16_t)(x))
+#define	htolel(x)	((u_int32_t)(x))
+#define	letohl(x)	((u_int32_t)(x))
+*/
+#endif	/* (BYTE_ORDER == LITTLE_ENDIAN) */
+
+
+#ifdef _KERNEL
+
+/*
+ * Type of copy for mb_{put|get}_mem()
+ */
+#define	MB_MSYSTEM	0		/* use bcopy() */
+#define MB_MUSER	1		/* use copyin()/copyout() */
+#define MB_MINLINE	2		/* use an inline copy loop */
+#define	MB_MZERO	3		/* bzero(), mb_put_mem only */
+#define	MB_MCUSTOM	4		/* use an user defined function */
+
+struct mbuf;
+struct mbchain;
+
+typedef int mb_copy_t(struct mbchain *mbp, c_caddr_t src, caddr_t dst, int len);
+
+struct mbchain {
+	struct mbuf *	mb_top;		/* head of mbufs chain */
+	struct mbuf * 	mb_cur;		/* current mbuf */
+	int		mb_mleft;	/* free space in the current mbuf */
+	int		mb_count;	/* total number of bytes */
+	mb_copy_t *	mb_copy;	/* user defined copy function */
+	void *		mb_udata;	/* user data */
+};
+
+struct mdchain {
+	struct mbuf *	md_top;		/* head of mbufs chain */
+	struct mbuf * 	md_cur;		/* current mbuf */
+	u_char *	md_pos;		/* offset in the current mbuf */
+};
+
+int  m_fixhdr(struct mbuf *m);
+
+int  mb_init(struct mbchain *mbp);
+void mb_initm(struct mbchain *mbp, struct mbuf *m);
+void mb_done(struct mbchain *mbp);
+struct mbuf *mb_detach(struct mbchain *mbp);
+int  mb_fixhdr(struct mbchain *mbp);
+caddr_t mb_reserve(struct mbchain *mbp, int size);
+
+int  mb_put_uint8(struct mbchain *mbp, u_int8_t x);
+int  mb_put_uint16be(struct mbchain *mbp, u_int16_t x);
+int  mb_put_uint16le(struct mbchain *mbp, u_int16_t x);
+int  mb_put_uint32be(struct mbchain *mbp, u_int32_t x);
+int  mb_put_uint32le(struct mbchain *mbp, u_int32_t x);
+int  mb_put_int64be(struct mbchain *mbp, int64_t x);
+int  mb_put_int64le(struct mbchain *mbp, int64_t x);
+int  mb_put_mem(struct mbchain *mbp, c_caddr_t source, int size, int type);
+int  mb_put_mbuf(struct mbchain *mbp, struct mbuf *m);
+int  mb_put_uio(struct mbchain *mbp, struct uio *uiop, int size);
+
+int  md_init(struct mdchain *mdp);
+void md_initm(struct mdchain *mbp, struct mbuf *m);
+void md_done(struct mdchain *mdp);
+void md_append_record(struct mdchain *mdp, struct mbuf *top);
+int  md_next_record(struct mdchain *mdp);
+int  md_get_uint8(struct mdchain *mdp, u_int8_t *x);
+int  md_get_uint16(struct mdchain *mdp, u_int16_t *x);
+int  md_get_uint16le(struct mdchain *mdp, u_int16_t *x);
+int  md_get_uint16be(struct mdchain *mdp, u_int16_t *x);
+int  md_get_uint32(struct mdchain *mdp, u_int32_t *x);
+int  md_get_uint32be(struct mdchain *mdp, u_int32_t *x);
+int  md_get_uint32le(struct mdchain *mdp, u_int32_t *x);
+int  md_get_int64(struct mdchain *mdp, int64_t *x);
+int  md_get_int64be(struct mdchain *mdp, int64_t *x);
+int  md_get_int64le(struct mdchain *mdp, int64_t *x);
+int  md_get_mem(struct mdchain *mdp, caddr_t target, int size, int type);
+int  md_get_mbuf(struct mdchain *mdp, int size, struct mbuf **m);
+int  md_get_uio(struct mdchain *mdp, struct uio *uiop, int size);
+
+#endif	/* ifdef _KERNEL */
+
+#endif	/* !_SYS_MCHAIN_H_ */