lib/libc/net/ns_parse.c

   1 /*
   2  * Copyright (c) 1996 by Internet Software Consortium.
   3  *
   4  * Permission to use, copy, modify, and distribute this software for any
   5  * purpose with or without fee is hereby granted, provided that the above
   6  * copyright notice and this permission notice appear in all copies.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
   9  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  10  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  11  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  12  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  13  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  14  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  15  * SOFTWARE.
  16  *
  17  * $FreeBSD: src/lib/libc/net/ns_parse.c,v 1.3 1999/08/28 00:00:14 peter Exp $
  18  * $DragonFly: src/lib/libc/net/ns_parse.c,v 1.2 2003/06/17 04:26:44 dillon Exp $
  19  */
  20
  21 #include <sys/types.h>
  22
  23 #include <netinet/in.h>
  24 #include <arpa/nameser.h>
  25
  26 #include <errno.h>
  27 #include <resolv.h>
  28 #include <string.h>
  29
  30 /* These need to be in the same order as the nres.h:ns_flag enum. */
  31 struct _ns_flagdata _ns_flagdata[16] = {
  32         { 0x8000, 15 },         /* qr. */
  33         { 0x7800, 11 },         /* opcode. */
  34         { 0x0400, 10 },         /* aa. */
  35         { 0x0200, 9 },          /* tc. */
  36         { 0x0100, 8 },          /* rd. */
  37         { 0x0080, 7 },          /* ra. */
  38         { 0x0040, 6 },          /* z. */
  39         { 0x0020, 5 },          /* ad. */
  40         { 0x0010, 4 },          /* cd. */
  41         { 0x000f, 0 },          /* rcode. */
  42         { 0x0000, 0 },          /* expansion (1/6). */
  43         { 0x0000, 0 },          /* expansion (2/6). */
  44         { 0x0000, 0 },          /* expansion (3/6). */
  45         { 0x0000, 0 },          /* expansion (4/6). */
  46         { 0x0000, 0 },          /* expansion (5/6). */
  47         { 0x0000, 0 },          /* expansion (6/6). */
  48 };
  49
  50 static int
  51 skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
  52         const u_char *optr = ptr;
  53
  54         for ((void)NULL; count > 0; count--) {
  55                 int b, rdlength;
  56
  57                 b = dn_skipname(ptr, eom);
  58                 if (b < 0)
  59                         goto emsgsize;
  60                 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
  61                 if (section != ns_s_qd) {
  62                         if (ptr + NS_INT32SZ > eom)
  63                                 goto emsgsize;
  64                         ptr += NS_INT32SZ/*TTL*/;
  65                         if (ptr + NS_INT16SZ > eom)
  66                                 goto emsgsize;
  67                         NS_GET16(rdlength, ptr);
  68                         ptr += rdlength/*RData*/;
  69                 }
  70         }
  71         if (ptr > eom)
  72                 goto emsgsize;
  73         return (ptr - optr);
  74  emsgsize:
  75         errno = EMSGSIZE;
  76         return (-1);
  77 }
  78
  79 int
  80 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
  81         const u_char *eom = msg + msglen;
  82         int i;
  83
  84         memset(handle, 0x5e, sizeof *handle);
  85         handle->_msg = msg;
  86         handle->_eom = eom;
  87         if (msg + NS_INT16SZ > eom)
  88                 goto emsgsize;
  89         NS_GET16(handle->_id, msg);
  90         if (msg + NS_INT16SZ > eom)
  91                 goto emsgsize;
  92         NS_GET16(handle->_flags, msg);
  93         for (i = 0; i < ns_s_max; i++) {
  94                 if (msg + NS_INT16SZ > eom)
  95                         goto emsgsize;
  96                 NS_GET16(handle->_counts[i], msg);
  97         }
  98         for (i = 0; i < ns_s_max; i++)
  99                 if (handle->_counts[i] == 0)
 100                         handle->_sections[i] = NULL;
 101                 else {
 102                         int b = skiprr(msg, eom, (ns_sect)i,
 103                                        handle->_counts[i]);
 104
 105                         if (b < 0)
 106                                 return (-1);
 107                         handle->_sections[i] = msg;
 108                         msg += b;
 109                 }
 110         if (msg != eom)
 111                 goto emsgsize;
 112         handle->_sect = ns_s_max;
 113         handle->_rrnum = -1;
 114         handle->_ptr = NULL;
 115         return (0);
 116  emsgsize:
 117         errno = EMSGSIZE;
 118         return (-1);
 119 }
 120
 121 int
 122 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
 123         int b;
 124
 125         /* Make section right. */
 126         if (section < 0 || section >= ns_s_max)
 127                 goto enodev;
 128         if ((int)section != (int)handle->_sect) {
 129                 handle->_sect = section;
 130                 handle->_rrnum = 0;
 131                 handle->_ptr = handle->_sections[(int)section];
 132         }
 133
 134         /* Make rrnum right. */
 135         if (rrnum == -1)
 136                 rrnum = handle->_rrnum;
 137         if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
 138                 goto enodev;
 139         if (rrnum < handle->_rrnum) {
 140                 handle->_rrnum = 0;
 141                 handle->_ptr = handle->_sections[(int)section];
 142         }
 143
 144         b = skiprr(handle->_msg, handle->_eom, section,
 145                    rrnum - handle->_rrnum);
 146         if (b < 0)
 147                 return (-1);
 148         handle->_ptr += b;
 149         handle->_rrnum = rrnum;
 150
 151         /* Do the parse. */
 152         b = dn_expand(handle->_msg, handle->_eom,
 153                       handle->_ptr, rr->name, NS_MAXDNAME);
 154         if (b < 0)
 155                 return (-1);
 156         handle->_ptr += b;
 157         if (handle->_ptr + NS_INT16SZ > handle->_eom)
 158                 goto emsgsize;
 159         NS_GET16(rr->type, handle->_ptr);
 160         if (handle->_ptr + NS_INT16SZ > handle->_eom)
 161                 goto emsgsize;
 162         NS_GET16(rr->rr_class, handle->_ptr);
 163         if (section == ns_s_qd) {
 164                 rr->ttl = 0;
 165                 rr->rdlength = 0;
 166                 rr->rdata = NULL;
 167         } else {
 168                 if (handle->_ptr + NS_INT32SZ > handle->_eom)
 169                         goto emsgsize;
 170                 NS_GET32(rr->ttl, handle->_ptr);
 171                 if (handle->_ptr + NS_INT16SZ > handle->_eom)
 172                         goto emsgsize;
 173                 NS_GET16(rr->rdlength, handle->_ptr);
 174                 if (handle->_ptr + rr->rdlength > handle->_eom)
 175                         goto emsgsize;
 176                 rr->rdata = handle->_ptr;
 177                 handle->_ptr += rr->rdlength;
 178         }
 179         handle->_rrnum++;
 180
 181         /* All done. */
 182         return (0);
 183  enodev:
 184         errno = ENODEV;
 185         return (-1);
 186  emsgsize:
 187         errno = EMSGSIZE;
 188         return (-1);
 189 }