resolv/ns_parse.c

   1 /*
   2  * Copyright (c) 1996,1999 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
  18 #if !defined(_LIBC) && !defined(lint)
  19 static const char rcsid[] = "$BINDId: ns_parse.c,v 8.13 1999/10/13 16:39:35 vixie Exp $";
  20 #endif
  21
  22 /* Import. */
  23
  24 #include <sys/types.h>
  25
  26 #include <netinet/in.h>
  27 #include <arpa/nameser.h>
  28
  29 #include <errno.h>
  30 #include <resolv.h>
  31 #include <string.h>
  32
  33 /* Forward. */
  34
  35 static void     setsection(ns_msg *msg, ns_sect sect);
  36
  37 /* Macros. */
  38
  39 #define RETERR(err) do { __set_errno (err); return (-1); } while (0)
  40
  41 /* Public. */
  42
  43 /* These need to be in the same order as the nres.h:ns_flag enum. */
  44 struct _ns_flagdata _ns_flagdata[16] = {
  45         { 0x8000, 15 },         /* qr. */
  46         { 0x7800, 11 },         /* opcode. */
  47         { 0x0400, 10 },         /* aa. */
  48         { 0x0200, 9 },          /* tc. */
  49         { 0x0100, 8 },          /* rd. */
  50         { 0x0080, 7 },          /* ra. */
  51         { 0x0040, 6 },          /* z. */
  52         { 0x0020, 5 },          /* ad. */
  53         { 0x0010, 4 },          /* cd. */
  54         { 0x000f, 0 },          /* rcode. */
  55         { 0x0000, 0 },          /* expansion (1/6). */
  56         { 0x0000, 0 },          /* expansion (2/6). */
  57         { 0x0000, 0 },          /* expansion (3/6). */
  58         { 0x0000, 0 },          /* expansion (4/6). */
  59         { 0x0000, 0 },          /* expansion (5/6). */
  60         { 0x0000, 0 },          /* expansion (6/6). */
  61 };
  62
  63 int
  64 ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
  65         const u_char *optr = ptr;
  66
  67         for ((void)NULL; count > 0; count--) {
  68                 int b, rdlength;
  69
  70                 b = dn_skipname(ptr, eom);
  71                 if (b < 0)
  72                         RETERR(EMSGSIZE);
  73                 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
  74                 if (section != ns_s_qd) {
  75                         if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
  76                                 RETERR(EMSGSIZE);
  77                         ptr += NS_INT32SZ/*TTL*/;
  78                         NS_GET16(rdlength, ptr);
  79                         ptr += rdlength/*RData*/;
  80                 }
  81         }
  82         if (ptr > eom)
  83                 RETERR(EMSGSIZE);
  84         return (ptr - optr);
  85 }
  86
  87 int
  88 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
  89         const u_char *eom = msg + msglen;
  90         int i;
  91
  92         memset(handle, 0x5e, sizeof *handle);
  93         handle->_msg = msg;
  94         handle->_eom = eom;
  95         if (msg + NS_INT16SZ > eom)
  96                 RETERR(EMSGSIZE);
  97         NS_GET16(handle->_id, msg);
  98         if (msg + NS_INT16SZ > eom)
  99                 RETERR(EMSGSIZE);
 100         NS_GET16(handle->_flags, msg);
 101         for (i = 0; i < ns_s_max; i++) {
 102                 if (msg + NS_INT16SZ > eom)
 103                         RETERR(EMSGSIZE);
 104                 NS_GET16(handle->_counts[i], msg);
 105         }
 106         for (i = 0; i < ns_s_max; i++)
 107                 if (handle->_counts[i] == 0)
 108                         handle->_sections[i] = NULL;
 109                 else {
 110                         int b = ns_skiprr(msg, eom, (ns_sect)i,
 111                                           handle->_counts[i]);
 112
 113                         if (b < 0)
 114                                 return (-1);
 115                         handle->_sections[i] = msg;
 116                         msg += b;
 117                 }
 118         if (msg != eom)
 119                 RETERR(EMSGSIZE);
 120         setsection(handle, ns_s_max);
 121         return (0);
 122 }
 123
 124 int
 125 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
 126         int b;
 127
 128         /* Make section right. */
 129         if (section < 0 || section >= ns_s_max)
 130                 RETERR(ENODEV);
 131         if (section != handle->_sect)
 132                 setsection(handle, section);
 133
 134         /* Make rrnum right. */
 135         if (rrnum == -1)
 136                 rrnum = handle->_rrnum;
 137         if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
 138                 RETERR(ENODEV);
 139         if (rrnum < handle->_rrnum)
 140                 setsection(handle, section);
 141         if (rrnum > handle->_rrnum) {
 142                 b = ns_skiprr(handle->_ptr, handle->_eom, section,
 143                               rrnum - handle->_rrnum);
 144
 145                 if (b < 0)
 146                         return (-1);
 147                 handle->_ptr += b;
 148                 handle->_rrnum = rrnum;
 149         }
 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 + NS_INT16SZ > handle->_eom)
 158                 RETERR(EMSGSIZE);
 159         NS_GET16(rr->type, handle->_ptr);
 160         NS_GET16(rr->rr_class, handle->_ptr);
 161         if (section == ns_s_qd) {
 162                 rr->ttl = 0;
 163                 rr->rdlength = 0;
 164                 rr->rdata = NULL;
 165         } else {
 166                 if (handle->_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
 167                         RETERR(EMSGSIZE);
 168                 NS_GET32(rr->ttl, handle->_ptr);
 169                 NS_GET16(rr->rdlength, handle->_ptr);
 170                 if (handle->_ptr + rr->rdlength > handle->_eom)
 171                         RETERR(EMSGSIZE);
 172                 rr->rdata = handle->_ptr;
 173                 handle->_ptr += rr->rdlength;
 174         }
 175         if (++handle->_rrnum > handle->_counts[(int)section])
 176                 setsection(handle, (ns_sect)((int)section + 1));
 177
 178         /* All done. */
 179         return (0);
 180 }
 181
 182 /* Private. */
 183
 184 static void
 185 setsection(ns_msg *msg, ns_sect sect) {
 186         msg->_sect = sect;
 187         if (sect == ns_s_max) {
 188                 msg->_rrnum = -1;
 189                 msg->_ptr = NULL;
 190         } else {
 191                 msg->_rrnum = 0;
 192                 msg->_ptr = msg->_sections[(int)sect];
 193         }
 194 }