resolv/ns_parse.c

   1 /*
   2  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (c) 1996,1999 by Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  15  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* Import. */
  19
  20 #include <sys/types.h>
  21
  22 #include <netinet/in.h>
  23 #include <arpa/nameser.h>
  24
  25 #include <errno.h>
  26 #include <resolv.h>
  27 #include <string.h>
  28
  29 /* Forward. */
  30
  31 static void     setsection(ns_msg *msg, ns_sect sect);
  32
  33 /* Macros. */
  34
  35 #define RETERR(err) do { __set_errno (err); return (-1); } while (0)
  36
  37 /* Public. */
  38
  39 /* These need to be in the same order as the nres.h:ns_flag enum. */
  40 const struct _ns_flagdata _ns_flagdata[16] = {
  41         { 0x8000, 15 },         /*%< qr. */
  42         { 0x7800, 11 },         /*%< opcode. */
  43         { 0x0400, 10 },         /*%< aa. */
  44         { 0x0200, 9 },          /*%< tc. */
  45         { 0x0100, 8 },          /*%< rd. */
  46         { 0x0080, 7 },          /*%< ra. */
  47         { 0x0040, 6 },          /*%< z. */
  48         { 0x0020, 5 },          /*%< ad. */
  49         { 0x0010, 4 },          /*%< cd. */
  50         { 0x000f, 0 },          /*%< rcode. */
  51         { 0x0000, 0 },          /*%< expansion (1/6). */
  52         { 0x0000, 0 },          /*%< expansion (2/6). */
  53         { 0x0000, 0 },          /*%< expansion (3/6). */
  54         { 0x0000, 0 },          /*%< expansion (4/6). */
  55         { 0x0000, 0 },          /*%< expansion (5/6). */
  56         { 0x0000, 0 },          /*%< expansion (6/6). */
  57 };
  58
  59 #undef ns_msg_getflag
  60 int ns_msg_getflag(ns_msg handle, int flag) {
  61         return(((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift);
  62 }
  63
  64 int
  65 ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
  66         const u_char *optr = ptr;
  67
  68         for ((void)NULL; count > 0; count--) {
  69                 int b, rdlength;
  70
  71                 b = dn_skipname(ptr, eom);
  72                 if (b < 0)
  73                         RETERR(EMSGSIZE);
  74                 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
  75                 if (section != ns_s_qd) {
  76                         if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
  77                                 RETERR(EMSGSIZE);
  78                         ptr += NS_INT32SZ/*TTL*/;
  79                         NS_GET16(rdlength, ptr);
  80                         ptr += rdlength/*RData*/;
  81                 }
  82         }
  83         if (ptr > eom)
  84                 RETERR(EMSGSIZE);
  85         return (ptr - optr);
  86 }
  87 libresolv_hidden_def (ns_skiprr)
  88
  89 int
  90 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
  91         const u_char *eom = msg + msglen;
  92         int i;
  93
  94         memset(handle, 0x5e, sizeof *handle);
  95         handle->_msg = msg;
  96         handle->_eom = eom;
  97         if (msg + NS_INT16SZ > eom)
  98                 RETERR(EMSGSIZE);
  99         NS_GET16(handle->_id, msg);
 100         if (msg + NS_INT16SZ > eom)
 101                 RETERR(EMSGSIZE);
 102         NS_GET16(handle->_flags, msg);
 103         for (i = 0; i < ns_s_max; i++) {
 104                 if (msg + NS_INT16SZ > eom)
 105                         RETERR(EMSGSIZE);
 106                 NS_GET16(handle->_counts[i], msg);
 107         }
 108         for (i = 0; i < ns_s_max; i++)
 109                 if (handle->_counts[i] == 0)
 110                         handle->_sections[i] = NULL;
 111                 else {
 112                         int b = ns_skiprr(msg, eom, (ns_sect)i,
 113                                           handle->_counts[i]);
 114
 115                         if (b < 0)
 116                                 return (-1);
 117                         handle->_sections[i] = msg;
 118                         msg += b;
 119                 }
 120         if (msg != eom)
 121                 RETERR(EMSGSIZE);
 122         setsection(handle, ns_s_max);
 123         return (0);
 124 }
 125 libresolv_hidden_def (ns_initparse)
 126
 127 int
 128 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
 129         int b;
 130         int tmp;
 131
 132         /* Make section right. */
 133         tmp = section;
 134         if (tmp < 0 || section >= ns_s_max)
 135                 RETERR(ENODEV);
 136         if (section != handle->_sect)
 137                 setsection(handle, section);
 138
 139         /* Make rrnum right. */
 140         if (rrnum == -1)
 141                 rrnum = handle->_rrnum;
 142         if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
 143                 RETERR(ENODEV);
 144         if (rrnum < handle->_rrnum)
 145                 setsection(handle, section);
 146         if (rrnum > handle->_rrnum) {
 147                 b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
 148                               rrnum - handle->_rrnum);
 149
 150                 if (b < 0)
 151                         return (-1);
 152                 handle->_msg_ptr += b;
 153                 handle->_rrnum = rrnum;
 154         }
 155
 156         /* Do the parse. */
 157         b = __libc_dn_expand (handle->_msg, handle->_eom,
 158                               handle->_msg_ptr, rr->name, NS_MAXDNAME);
 159         if (b < 0)
 160                 return (-1);
 161         handle->_msg_ptr += b;
 162         if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
 163                 RETERR(EMSGSIZE);
 164         NS_GET16(rr->type, handle->_msg_ptr);
 165         NS_GET16(rr->rr_class, handle->_msg_ptr);
 166         if (section == ns_s_qd) {
 167                 rr->ttl = 0;
 168                 rr->rdlength = 0;
 169                 rr->rdata = NULL;
 170         } else {
 171                 if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
 172                         RETERR(EMSGSIZE);
 173                 NS_GET32(rr->ttl, handle->_msg_ptr);
 174                 NS_GET16(rr->rdlength, handle->_msg_ptr);
 175                 if (handle->_msg_ptr + rr->rdlength > handle->_eom)
 176                         RETERR(EMSGSIZE);
 177                 rr->rdata = handle->_msg_ptr;
 178                 handle->_msg_ptr += rr->rdlength;
 179         }
 180         if (++handle->_rrnum > handle->_counts[(int)section])
 181                 setsection(handle, (ns_sect)((int)section + 1));
 182
 183         /* All done. */
 184         return (0);
 185 }
 186 libresolv_hidden_def (ns_parserr)
 187
 188 /* Private. */
 189
 190 static void
 191 setsection(ns_msg *msg, ns_sect sect) {
 192         msg->_sect = sect;
 193         if (sect == ns_s_max) {
 194                 msg->_rrnum = -1;
 195                 msg->_msg_ptr = NULL;
 196         } else {
 197                 msg->_rrnum = 0;
 198                 msg->_msg_ptr = msg->_sections[(int)sect];
 199         }
 200 }
 201
 202 /*! \file */