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 #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 const 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 #undef ns_msg_getflag
  64 int ns_msg_getflag(ns_msg handle, int flag) {
  65         return(((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift);
  66 }
  67
  68 int
  69 ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
  70         const u_char *optr = ptr;
  71
  72         for ((void)NULL; count > 0; count--) {
  73                 int b, rdlength;
  74
  75                 b = dn_skipname(ptr, eom);
  76                 if (b < 0)
  77                         RETERR(EMSGSIZE);
  78                 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
  79                 if (section != ns_s_qd) {
  80                         if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
  81                                 RETERR(EMSGSIZE);
  82                         ptr += NS_INT32SZ/*TTL*/;
  83                         NS_GET16(rdlength, ptr);
  84                         ptr += rdlength/*RData*/;
  85                 }
  86         }
  87         if (ptr > eom)
  88                 RETERR(EMSGSIZE);
  89         return (ptr - optr);
  90 }
  91 libresolv_hidden_def (ns_skiprr)
  92
  93 int
  94 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
  95         const u_char *eom = msg + msglen;
  96         int i;
  97
  98         memset(handle, 0x5e, sizeof *handle);
  99         handle->_msg = msg;
 100         handle->_eom = eom;
 101         if (msg + NS_INT16SZ > eom)
 102                 RETERR(EMSGSIZE);
 103         NS_GET16(handle->_id, msg);
 104         if (msg + NS_INT16SZ > eom)
 105                 RETERR(EMSGSIZE);
 106         NS_GET16(handle->_flags, msg);
 107         for (i = 0; i < ns_s_max; i++) {
 108                 if (msg + NS_INT16SZ > eom)
 109                         RETERR(EMSGSIZE);
 110                 NS_GET16(handle->_counts[i], msg);
 111         }
 112         for (i = 0; i < ns_s_max; i++)
 113                 if (handle->_counts[i] == 0)
 114                         handle->_sections[i] = NULL;
 115                 else {
 116                         int b = ns_skiprr(msg, eom, (ns_sect)i,
 117                                           handle->_counts[i]);
 118
 119                         if (b < 0)
 120                                 return (-1);
 121                         handle->_sections[i] = msg;
 122                         msg += b;
 123                 }
 124         if (msg != eom)
 125                 RETERR(EMSGSIZE);
 126         setsection(handle, ns_s_max);
 127         return (0);
 128 }
 129 libresolv_hidden_def (ns_initparse)
 130
 131 int
 132 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
 133         int b;
 134         int tmp;
 135
 136         /* Make section right. */
 137         tmp = section;
 138         if (tmp < 0 || section >= ns_s_max)
 139                 RETERR(ENODEV);
 140         if (section != handle->_sect)
 141                 setsection(handle, section);
 142
 143         /* Make rrnum right. */
 144         if (rrnum == -1)
 145                 rrnum = handle->_rrnum;
 146         if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
 147                 RETERR(ENODEV);
 148         if (rrnum < handle->_rrnum)
 149                 setsection(handle, section);
 150         if (rrnum > handle->_rrnum) {
 151                 b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
 152                               rrnum - handle->_rrnum);
 153
 154                 if (b < 0)
 155                         return (-1);
 156                 handle->_msg_ptr += b;
 157                 handle->_rrnum = rrnum;
 158         }
 159
 160         /* Do the parse. */
 161         b = dn_expand(handle->_msg, handle->_eom,
 162                       handle->_msg_ptr, rr->name, NS_MAXDNAME);
 163         if (b < 0)
 164                 return (-1);
 165         handle->_msg_ptr += b;
 166         if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
 167                 RETERR(EMSGSIZE);
 168         NS_GET16(rr->type, handle->_msg_ptr);
 169         NS_GET16(rr->rr_class, handle->_msg_ptr);
 170         if (section == ns_s_qd) {
 171                 rr->ttl = 0;
 172                 rr->rdlength = 0;
 173                 rr->rdata = NULL;
 174         } else {
 175                 if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
 176                         RETERR(EMSGSIZE);
 177                 NS_GET32(rr->ttl, handle->_msg_ptr);
 178                 NS_GET16(rr->rdlength, handle->_msg_ptr);
 179                 if (handle->_msg_ptr + rr->rdlength > handle->_eom)
 180                         RETERR(EMSGSIZE);
 181                 rr->rdata = handle->_msg_ptr;
 182                 handle->_msg_ptr += rr->rdlength;
 183         }
 184         if (++handle->_rrnum > handle->_counts[(int)section])
 185                 setsection(handle, (ns_sect)((int)section + 1));
 186
 187         /* All done. */
 188         return (0);
 189 }
 190 libresolv_hidden_def (ns_parserr)
 191
 192 /* Private. */
 193
 194 static void
 195 setsection(ns_msg *msg, ns_sect sect) {
 196         msg->_sect = sect;
 197         if (sect == ns_s_max) {
 198                 msg->_rrnum = -1;
 199                 msg->_msg_ptr = NULL;
 200         } else {
 201                 msg->_rrnum = 0;
 202                 msg->_msg_ptr = msg->_sections[(int)sect];
 203         }
 204 }
 205
 206 /*! \file */