lib/libc/nameser/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  * $Id: ns_parse.c,v 1.9 2007/08/27 03:32:26 marka Exp $
  18  */
  19
  20 /* Import. */
  21
  22 #include "port_before.h"
  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 #include "port_after.h"
  34
  35 /* Forward. */
  36
  37 static void     setsection(ns_msg *msg, ns_sect sect);
  38
  39 /* Macros. */
  40
  41 #if !defined(SOLARIS2) || defined(__COVERITY__)
  42 #define RETERR(err) do { errno = (err); return (-1); } while (0)
  43 #else
  44 #define RETERR(err) \
  45         do { errno = (err); if (errno == errno) return (-1); } while (0)
  46 #endif
  47
  48 /* Public. */
  49
  50 /* These need to be in the same order as the nres.h:ns_flag enum. */
  51 struct _ns_flagdata _ns_flagdata[16] = {
  52         { 0x8000, 15 },         /*%< qr. */
  53         { 0x7800, 11 },         /*%< opcode. */
  54         { 0x0400, 10 },         /*%< aa. */
  55         { 0x0200, 9 },          /*%< tc. */
  56         { 0x0100, 8 },          /*%< rd. */
  57         { 0x0080, 7 },          /*%< ra. */
  58         { 0x0040, 6 },          /*%< z. */
  59         { 0x0020, 5 },          /*%< ad. */
  60         { 0x0010, 4 },          /*%< cd. */
  61         { 0x000f, 0 },          /*%< rcode. */
  62         { 0x0000, 0 },          /*%< expansion (1/6). */
  63         { 0x0000, 0 },          /*%< expansion (2/6). */
  64         { 0x0000, 0 },          /*%< expansion (3/6). */
  65         { 0x0000, 0 },          /*%< expansion (4/6). */
  66         { 0x0000, 0 },          /*%< expansion (5/6). */
  67         { 0x0000, 0 },          /*%< expansion (6/6). */
  68 };
  69
  70 int ns_msg_getflag(ns_msg handle, int flag) {
  71         return(((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift);
  72 }
  73
  74 int
  75 ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {
  76         const u_char *optr = ptr;
  77
  78         for ((void)NULL; count > 0; count--) {
  79                 int b, rdlength;
  80
  81                 b = dn_skipname(ptr, eom);
  82                 if (b < 0)
  83                         RETERR(EMSGSIZE);
  84                 ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;
  85                 if (section != ns_s_qd) {
  86                         if (ptr + NS_INT32SZ + NS_INT16SZ > eom)
  87                                 RETERR(EMSGSIZE);
  88                         ptr += NS_INT32SZ/*TTL*/;
  89                         NS_GET16(rdlength, ptr);
  90                         ptr += rdlength/*RData*/;
  91                 }
  92         }
  93         if (ptr > eom)
  94                 RETERR(EMSGSIZE);
  95         return (ptr - optr);
  96 }
  97
  98 int
  99 ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
 100         const u_char *eom = msg + msglen;
 101         int i;
 102
 103         memset(handle, 0x5e, sizeof *handle);
 104         handle->_msg = msg;
 105         handle->_eom = eom;
 106         if (msg + NS_INT16SZ > eom)
 107                 RETERR(EMSGSIZE);
 108         NS_GET16(handle->_id, msg);
 109         if (msg + NS_INT16SZ > eom)
 110                 RETERR(EMSGSIZE);
 111         NS_GET16(handle->_flags, msg);
 112         for (i = 0; i < ns_s_max; i++) {
 113                 if (msg + NS_INT16SZ > eom)
 114                         RETERR(EMSGSIZE);
 115                 NS_GET16(handle->_counts[i], msg);
 116         }
 117         for (i = 0; i < ns_s_max; i++)
 118                 if (handle->_counts[i] == 0)
 119                         handle->_sections[i] = NULL;
 120                 else {
 121                         int b = ns_skiprr(msg, eom, (ns_sect)i,
 122                                           handle->_counts[i]);
 123
 124                         if (b < 0)
 125                                 return (-1);
 126                         handle->_sections[i] = msg;
 127                         msg += b;
 128                 }
 129         if (msg != eom)
 130                 RETERR(EMSGSIZE);
 131         setsection(handle, ns_s_max);
 132         return (0);
 133 }
 134
 135 int
 136 ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {
 137         int b;
 138         int tmp;
 139
 140         /* Make section right. */
 141         tmp = section;
 142         if (tmp < 0 || section >= ns_s_max)
 143                 RETERR(ENODEV);
 144         if (section != handle->_sect)
 145                 setsection(handle, section);
 146
 147         /* Make rrnum right. */
 148         if (rrnum == -1)
 149                 rrnum = handle->_rrnum;
 150         if (rrnum < 0 || rrnum >= handle->_counts[(int)section])
 151                 RETERR(ENODEV);
 152         if (rrnum < handle->_rrnum)
 153                 setsection(handle, section);
 154         if (rrnum > handle->_rrnum) {
 155                 b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,
 156                               rrnum - handle->_rrnum);
 157
 158                 if (b < 0)
 159                         return (-1);
 160                 handle->_msg_ptr += b;
 161                 handle->_rrnum = rrnum;
 162         }
 163
 164         /* Do the parse. */
 165         b = dn_expand(handle->_msg, handle->_eom,
 166                       handle->_msg_ptr, rr->name, NS_MAXDNAME);
 167         if (b < 0)
 168                 return (-1);
 169         handle->_msg_ptr += b;
 170         if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)
 171                 RETERR(EMSGSIZE);
 172         NS_GET16(rr->type, handle->_msg_ptr);
 173         NS_GET16(rr->rr_class, handle->_msg_ptr);
 174         if (section == ns_s_qd) {
 175                 rr->ttl = 0;
 176                 rr->rdlength = 0;
 177                 rr->rdata = NULL;
 178         } else {
 179                 if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)
 180                         RETERR(EMSGSIZE);
 181                 NS_GET32(rr->ttl, handle->_msg_ptr);
 182                 NS_GET16(rr->rdlength, handle->_msg_ptr);
 183                 if (handle->_msg_ptr + rr->rdlength > handle->_eom)
 184                         RETERR(EMSGSIZE);
 185                 rr->rdata = handle->_msg_ptr;
 186                 handle->_msg_ptr += rr->rdlength;
 187         }
 188         if (++handle->_rrnum > handle->_counts[(int)section])
 189                 setsection(handle, (ns_sect)((int)section + 1));
 190
 191         /* All done. */
 192         return (0);
 193 }
 194
 195 /* Private. */
 196
 197 static void
 198 setsection(ns_msg *msg, ns_sect sect) {
 199         msg->_sect = sect;
 200         if (sect == ns_s_max) {
 201                 msg->_rrnum = -1;
 202                 msg->_msg_ptr = NULL;
 203         } else {
 204                 msg->_rrnum = 0;
 205                 msg->_msg_ptr = msg->_sections[(int)sect];
 206         }
 207 }
 208
 209 /*! \file */