The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/xdr/xdr_mbuf.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2008 Isilon Inc http://www.isilon.com/
    5  * Authors: Doug Rabson <dfr@rabson.org>
    6  * Developed with Red Inc: Alfred Perlstein <alfred@freebsd.org>
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  */
   29 
   30 #include <sys/cdefs.h>
   31 __FBSDID("$FreeBSD: stable/12/sys/xdr/xdr_mbuf.c 326272 2017-11-27 15:23:17Z pfg $");
   32 
   33 #include <sys/param.h>
   34 #include <sys/systm.h>
   35 #include <sys/malloc.h>
   36 #include <sys/mbuf.h>
   37 
   38 #include <rpc/types.h>
   39 #include <rpc/xdr.h>
   40 
   41 static void xdrmbuf_destroy(XDR *);
   42 static bool_t xdrmbuf_getlong(XDR *, long *);
   43 static bool_t xdrmbuf_putlong(XDR *, const long *);
   44 static bool_t xdrmbuf_getbytes(XDR *, char *, u_int);
   45 static bool_t xdrmbuf_putbytes(XDR *, const char *, u_int);
   46 /* XXX: w/64-bit pointers, u_int not enough! */
   47 static u_int xdrmbuf_getpos(XDR *);
   48 static bool_t xdrmbuf_setpos(XDR *, u_int);
   49 static int32_t *xdrmbuf_inline(XDR *, u_int);
   50 
   51 static const struct     xdr_ops xdrmbuf_ops = {
   52         xdrmbuf_getlong,
   53         xdrmbuf_putlong,
   54         xdrmbuf_getbytes,
   55         xdrmbuf_putbytes,
   56         xdrmbuf_getpos,
   57         xdrmbuf_setpos,
   58         xdrmbuf_inline,
   59         xdrmbuf_destroy
   60 };
   61 
   62 /*
   63  * The procedure xdrmbuf_create initializes a stream descriptor for a
   64  * mbuf.
   65  */
   66 void
   67 xdrmbuf_create(XDR *xdrs, struct mbuf *m, enum xdr_op op)
   68 {
   69 
   70         KASSERT(m != NULL, ("xdrmbuf_create with NULL mbuf chain"));
   71         xdrs->x_op = op;
   72         xdrs->x_ops = &xdrmbuf_ops;
   73         xdrs->x_base = (char *) m;
   74         if (op == XDR_ENCODE) {
   75                 m = m_last(m);
   76                 xdrs->x_private = m;
   77                 xdrs->x_handy = m->m_len;
   78         } else {
   79                 xdrs->x_private = m;
   80                 xdrs->x_handy = 0;
   81         }
   82 }
   83 
   84 void
   85 xdrmbuf_append(XDR *xdrs, struct mbuf *madd)
   86 {
   87         struct mbuf *m;
   88 
   89         KASSERT(xdrs->x_ops == &xdrmbuf_ops && xdrs->x_op == XDR_ENCODE,
   90             ("xdrmbuf_append: invalid XDR stream"));
   91 
   92         if (m_length(madd, NULL) == 0) {
   93                 m_freem(madd);
   94                 return;
   95         }
   96         
   97         m = (struct mbuf *) xdrs->x_private;
   98         m->m_next = madd;
   99 
  100         m = m_last(madd);
  101         xdrs->x_private = m;
  102         xdrs->x_handy = m->m_len;
  103 }
  104 
  105 struct mbuf *
  106 xdrmbuf_getall(XDR *xdrs)
  107 {
  108         struct mbuf *m0, *m;
  109 
  110         KASSERT(xdrs->x_ops == &xdrmbuf_ops && xdrs->x_op == XDR_DECODE,
  111             ("xdrmbuf_append: invalid XDR stream"));
  112 
  113         m0 = (struct mbuf *) xdrs->x_base;
  114         m = (struct mbuf *) xdrs->x_private;
  115         if (m0 != m) {
  116                 while (m0->m_next != m)
  117                         m0 = m0->m_next;
  118                 m0->m_next = NULL;
  119                 xdrs->x_private = NULL;
  120         } else {
  121                 xdrs->x_base = NULL;
  122                 xdrs->x_private = NULL;
  123         }
  124 
  125         if (m)
  126                 m_adj(m, xdrs->x_handy);
  127         else
  128                 m = m_get(M_WAITOK, MT_DATA);
  129         return (m);
  130 }
  131 
  132 static void
  133 xdrmbuf_destroy(XDR *xdrs)
  134 {
  135 
  136         if (xdrs->x_op == XDR_DECODE && xdrs->x_base) {
  137                 m_freem((struct mbuf *) xdrs->x_base);
  138                 xdrs->x_base = NULL;
  139                 xdrs->x_private = NULL;
  140         }
  141 }
  142 
  143 static bool_t
  144 xdrmbuf_getlong(XDR *xdrs, long *lp)
  145 {
  146         int32_t *p;
  147         int32_t t;
  148 
  149         p = xdrmbuf_inline(xdrs, sizeof(int32_t));
  150         if (p) {
  151                 t = *p;
  152         } else {
  153                 xdrmbuf_getbytes(xdrs, (char *) &t, sizeof(int32_t));
  154         }
  155 
  156         *lp = ntohl(t);
  157         return (TRUE);
  158 }
  159 
  160 static bool_t
  161 xdrmbuf_putlong(xdrs, lp)
  162         XDR *xdrs;
  163         const long *lp;
  164 {
  165         int32_t *p;
  166         int32_t t = htonl(*lp);
  167 
  168         p = xdrmbuf_inline(xdrs, sizeof(int32_t));
  169         if (p) {
  170                 *p = t;
  171                 return (TRUE);
  172         } else {
  173                 return (xdrmbuf_putbytes(xdrs, (char *) &t, sizeof(int32_t)));
  174         }
  175 }
  176 
  177 static bool_t
  178 xdrmbuf_getbytes(XDR *xdrs, char *addr, u_int len)
  179 {
  180         struct mbuf *m = (struct mbuf *) xdrs->x_private;
  181         size_t sz;
  182 
  183         while (len > 0) {
  184                 /*
  185                  * Make sure we haven't hit the end.
  186                  */
  187                 if (!m) {
  188                         return (FALSE);
  189                 }
  190 
  191                 /*
  192                  * See how much we can get from this mbuf.
  193                  */
  194                 sz = m->m_len - xdrs->x_handy;
  195                 if (sz > len)
  196                         sz = len;
  197                 bcopy(mtod(m, const char *) + xdrs->x_handy, addr, sz);
  198 
  199                 addr += sz;
  200                 xdrs->x_handy += sz;
  201                 len -= sz;
  202 
  203                 if (xdrs->x_handy == m->m_len) {
  204                         m = m->m_next;
  205                         xdrs->x_private = (void *) m;
  206                         xdrs->x_handy = 0;
  207                 }
  208         }
  209         
  210         return (TRUE);
  211 }
  212 
  213 static bool_t
  214 xdrmbuf_putbytes(XDR *xdrs, const char *addr, u_int len)
  215 {
  216         struct mbuf *m = (struct mbuf *) xdrs->x_private;
  217         struct mbuf *n;
  218         size_t sz;
  219 
  220         while (len > 0) {
  221                 sz = M_TRAILINGSPACE(m) + (m->m_len - xdrs->x_handy);
  222                 if (sz > len)
  223                         sz = len;
  224                 bcopy(addr, mtod(m, char *) + xdrs->x_handy, sz);
  225                 addr += sz;
  226                 xdrs->x_handy += sz;
  227                 if (xdrs->x_handy > m->m_len)
  228                         m->m_len = xdrs->x_handy;
  229                 len -= sz;
  230 
  231                 if (xdrs->x_handy == m->m_len && M_TRAILINGSPACE(m) == 0) {
  232                         if (!m->m_next) {
  233                                 if (m->m_flags & M_EXT)
  234                                         n = m_getcl(M_WAITOK, m->m_type, 0);
  235                                 else
  236                                         n = m_get(M_WAITOK, m->m_type);
  237                                 m->m_next = n;
  238                         }
  239                         m = m->m_next;
  240                         xdrs->x_private = (void *) m;
  241                         xdrs->x_handy = 0;
  242                 }
  243         }
  244         
  245         return (TRUE);
  246 }
  247 
  248 static u_int
  249 xdrmbuf_getpos(XDR *xdrs)
  250 {
  251         struct mbuf *m0 = (struct mbuf *) xdrs->x_base;
  252         struct mbuf *m = (struct mbuf *) xdrs->x_private;
  253         u_int pos = 0;
  254 
  255         while (m0 && m0 != m) {
  256                 pos += m0->m_len;
  257                 m0 = m0->m_next;
  258         }
  259         KASSERT(m0, ("Corrupted mbuf chain"));
  260 
  261         return (pos + xdrs->x_handy);
  262 }
  263 
  264 static bool_t
  265 xdrmbuf_setpos(XDR *xdrs, u_int pos)
  266 {
  267         struct mbuf *m = (struct mbuf *) xdrs->x_base;
  268 
  269         while (m && pos > m->m_len) {
  270                 pos -= m->m_len;
  271                 m = m->m_next;
  272         }
  273         KASSERT(m, ("Corrupted mbuf chain"));
  274 
  275         xdrs->x_private = (void *) m;
  276         xdrs->x_handy = pos;
  277 
  278         return (TRUE);
  279 }
  280 
  281 static int32_t *
  282 xdrmbuf_inline(XDR *xdrs, u_int len)
  283 {
  284         struct mbuf *m = (struct mbuf *) xdrs->x_private;
  285         size_t available;
  286         char *p;
  287 
  288         if (!m)
  289                 return (0);
  290         if (xdrs->x_op == XDR_ENCODE) {
  291                 available = M_TRAILINGSPACE(m) + (m->m_len - xdrs->x_handy);
  292         } else {
  293                 available = m->m_len - xdrs->x_handy;
  294         }
  295 
  296         if (available >= len) {
  297                 p = mtod(m, char *) + xdrs->x_handy;
  298                 if (((uintptr_t) p) & (sizeof(int32_t) - 1))
  299                         return (0);
  300                 xdrs->x_handy += len;
  301                 if (xdrs->x_handy > m->m_len)
  302                         m->m_len = xdrs->x_handy;
  303                 return ((int32_t *) p);
  304         }
  305 
  306         return (0);
  307 }

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