dist/dhcp/minires/ns_parse.c

   1 /*
   2  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (c) 1996-2003 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  *   Internet Systems Consortium, Inc.
  18  *   950 Charter Street
  19  *   Redwood City, CA 94063
  20  *   <info@isc.org>
  21  *   http://www.isc.org/
  22  */
  23
  24 #ifndef lint
  25 static const char rcsid[] = "$Id: ns_parse.c,v 1.6 2005/08/11 17:13:26 drochner Exp $";
  26 #endif
  27
  28 /* Import. */
  29
  30 #include <sys/types.h>
  31
  32 #include <netinet/in.h>
  33 #include <sys/socket.h>
  34
  35 #include <errno.h>
  36 #include <string.h>
  37
  38 #include "minires/minires.h"
  39 #include "arpa/nameser.h"
  40
  41 /* Forward. */
  42
  43 static void     setsection(ns_msg *msg, ns_sect sect);
  44
  45 /* Macros. */
  46
  47 /* Public. */
  48
  49 /* These need to be in the same order as the nres.h:ns_flag enum. */
  50 struct _ns_flagdata _ns_flagdata[16] = {
  51         { 0x8000, 15 },         /* qr. */
  52         { 0x7800, 11 },         /* opcode. */
  53         { 0x0400, 10 },         /* aa. */
  54         { 0x0200, 9 },          /* tc. */
  55         { 0x0100, 8 },          /* rd. */
  56         { 0x0080, 7 },          /* ra. */
  57         { 0x0040, 6 },          /* z. */
  58         { 0x0020, 5 },          /* ad. */
  59         { 0x0010, 4 },          /* cd. */
  60         { 0x000f, 0 },          /* rcode. */
  61         { 0x0000, 0 },          /* expansion (1/6). */
  62         { 0x0000, 0 },          /* expansion (2/6). */
  63         { 0x0000, 0 },          /* expansion (3/6). */
  64         { 0x0000, 0 },          /* expansion (4/6). */
  65         { 0x0000, 0 },          /* expansion (5/6). */
  66         { 0x0000, 0 },          /* expansion (6/6). */
  67 };
  68
  69 isc_result_t
  70 ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count,
  71           int *rc) {
  72         const u_char *optr = ptr;
  73
  74         for ((void)NULL; count > 0; count--) {
  75                 int b, rdlength;
  76
  77                 b = dn_skipname(ptr, eom);
  78                 if (b < 0)
  79                         return ISC_R_INCOMPLETE;
  80                 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
  81                 if (section != ns_s_qd) {
  82                         if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
  83                                 return ISC_R_INCOMPLETE;
  84                         ptr += NS_INT32SZ/*TTL*/;
  85                         rdlength = getUShort(ptr);
  86                         ptr += 2;
  87                         ptr += rdlength/*RData*/;
  88                 }
  89         }
  90         if (ptr > eom)
  91                 return ISC_R_INCOMPLETE;
  92         if (rc)
  93                 *rc = ptr - optr;
  94         return ISC_R_SUCCESS;
  95 }
  96
  97 isc_result_t
  98 ns_initparse(const u_char *msg, unsigned msglen, ns_msg *handle) {
  99         const u_char *eom = msg + msglen;
 100         int i;
 101
 102         memset(handle, 0x5e, sizeof *handle);
 103         handle->_msg = msg;
 104         handle->_eom = eom;
 105         if (msg + NS_INT16SZ > eom)
 106                 return ISC_R_INCOMPLETE;
 107         handle->_id = getUShort (msg);
 108         msg += 2;
 109         if (msg + NS_INT16SZ > eom)
 110                 return ISC_R_INCOMPLETE;
 111         handle->_flags = getUShort (msg);
 112         msg += 2;
 113         for (i = 0; i < ns_s_max; i++) {
 114                 if (msg + NS_INT16SZ > eom)
 115                         return ISC_R_INCOMPLETE;
 116                 handle->_counts[i] = getUShort (msg);
 117                 msg += 2;
 118         }
 119         for (i = 0; i < ns_s_max; i++)
 120                 if (handle->_counts[i] == 0)
 121                         handle->_sections[i] = NULL;
 122                 else {
 123                         int b;
 124                         isc_result_t status =
 125                                 ns_skiprr(msg, eom, (ns_sect)i,
 126                                           handle->_counts[i], &b);
 127
 128                         if (status != ISC_R_SUCCESS)
 129                                 return STATUS;
 130                         handle->_sections[i] = msg;
 131                         msg += b;
 132                 }
 133         if (msg != eom)
 134                 return ISC_R_INCOMPLETE;
 135         setsection(handle, ns_s_max);
 136         return ISC_R_SUCCESS;
 137 }
 138
 139 isc_result_t
 140 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
 141         int b;
 142         isc_result_t status;
 143         int tmp; /* XXX used to force a signed comparison below */
 144
 145         /* Make section right. */
 146         if ((tmp = section) < 0 || section >= ns_s_max)
 147                 return ISC_R_NOTIMPLEMENTED;
 148         if (section != handle->_sect)
 149                 setsection(handle, section);
 150
 151         /* Make rrnum right. */
 152         if (rrnum == -1)
 153                 rrnum = handle->_rrnum;
 154         if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
 155                 return ISC_R_UNKNOWNATTRIBUTE;
 156         if (rrnum < handle->_rrnum)
 157                 setsection(handle, section);
 158         if (rrnum > handle->_rrnum) {
 159                 status = ns_skiprr(handle->_ptr, handle->_eom, section,
 160                               rrnum - handle->_rrnum, &b);
 161
 162                 if (status != ISC_R_SUCCESS)
 163                         return status;
 164                 handle->_ptr += b;
 165                 handle->_rrnum = rrnum;
 166         }
 167
 168         /* Do the parse. */
 169         b = dn_expand(handle->_msg, handle->_eom,
 170                       handle->_ptr, rr->name, NS_MAXDNAME);
 171         if (b < 0)
 172                 return ISC_R_FORMERR;
 173         handle->_ptr += b;
 174         if (handle->_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
 175                 return ISC_R_INCOMPLETE;
 176         rr->type = getUShort (handle->_ptr);
 177         handle -> _ptr += 2;
 178         rr->rr_class = getUShort (handle->_ptr);
 179         handle -> _ptr += 2;
 180         if (section == ns_s_qd) {
 181                 rr->ttl = 0;
 182                 rr->rdlength = 0;
 183                 rr->rdata = NULL;
 184         } else {
 185                 if (handle->_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
 186                         return ISC_R_INCOMPLETE;
 187                 rr->ttl = getULong (handle->_ptr);
 188                 handle -> _ptr += 4;
 189                 rr->rdlength = getUShort (handle->_ptr);
 190                 handle -> _ptr += 2;
 191                 if (handle->_ptr + rr->rdlength > handle->_eom)
 192                         return ISC_R_INCOMPLETE;
 193                 rr->rdata = handle->_ptr;
 194                 handle->_ptr += rr->rdlength;
 195         }
 196         if (++handle->_rrnum > handle->_counts[(int)section])
 197                 setsection(handle, (ns_sect)((int)section + 1));
 198
 199         /* All done. */
 200         return ISC_R_SUCCESS;
 201 }
 202
 203 /* Private. */
 204
 205 static void
 206 setsection(ns_msg *msg, ns_sect sect) {
 207         msg->_sect = sect;
 208         if (sect == ns_s_max) {
 209                 msg->_rrnum = -1;
 210                 msg->_ptr = NULL;
 211         } else {
 212                 msg->_rrnum = 0;
 213                 msg->_ptr = msg->_sections[(int)sect];
 214         }
 215 }