mdw@git.distorted.org.uk Git - adns/blob - src/parse.c

   1 /*
   2  * parse.c
   3  * - parsing assistance functions (mainly for domains inside datagrams)
   4  */
   5 /*
   6  *  This file is part of adns, which is Copyright (C) 1997, 1998 Ian Jackson
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 2, or (at your option)
  11  *  any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to the Free Software Foundation,
  20  *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  21  */
  22
  23 #include "internal.h"
  24
  25 int vbuf__append_quoted1035(vbuf *vb, const byte *buf, int len) {
  26   char qbuf[10];
  27   int i, ch;
  28
  29   while (len) {
  30     qbuf[0]= 0;
  31     for (i=0; i<len; i++) {
  32       ch= buf[i];
  33       if (ch == '.' || ch == '"' || ch == '(' || ch == ')' ||
  34           ch == '@' || ch == ';' || ch == '$') {
  35         sprintf(qbuf,"\\%c",ch);
  36         break;
  37       } else if (ch <= ' ' || ch >= 127) {
  38         sprintf(qbuf,"\\%03o",ch);
  39         break;
  40       }
  41     }
  42     if (!adns__vbuf_append(vb,buf,i) || !adns__vbuf_append(vb,qbuf,strlen(qbuf)))
  43       return 0;
  44     buf+= i; len-= i;
  45   }
  46   return 1;
  47 }
  48
  49 void adns__findlabel_start(findlabel_state *fls, adns_state ads,
  50                            int serv, adns_query qu,
  51                            const byte *dgram, int dglen, int max,
  52                            int dmbegin, int *dmend_rlater) {
  53   fls->ads= ads;
  54   fls->qu= qu;
  55   fls->serv= serv;
  56   fls->dgram= dgram;
  57   fls->dglen= dglen;
  58   fls->max= max;
  59   fls->cbyte= dmbegin;
  60   fls->namelen= 0;
  61   fls->dmend_r= dmend_rlater;
  62 }
  63
  64 adns_status adns__findlabel_next(findlabel_state *fls,
  65                                  int *lablen_r, int *labstart_r) {
  66   int lablen, jumped, jumpto;
  67   const char *dgram;
  68
  69   jumped= 0;
  70   dgram= fls->dgram;
  71   for (;;) {
  72     if (fls->cbyte >= fls->dglen) goto x_truncated;
  73     if (fls->cbyte >= fls->max) goto x_serverfaulty;
  74     GET_B(fls->cbyte,lablen);
  75     if (!(lablen & 0x0c0)) break;
  76     if ((lablen & 0x0c0) != 0x0c0) return adns_s_unknownreply;
  77     if (jumped++) {
  78       adns__diag(fls->ads,fls->serv,fls->qu,"compressed datagram contains loop");
  79       return adns_s_serverfaulty;
  80     }
  81     if (fls->cbyte >= fls->dglen) goto x_truncated;
  82     if (fls->cbyte >= fls->max) goto x_serverfaulty;
  83     GET_B(fls->cbyte,jumpto);
  84     jumpto |= (lablen&0x3f)<<8;
  85     if (fls->dmend_r) *(fls->dmend_r)= fls->cbyte;
  86     fls->cbyte= jumpto;
  87     fls->dmend_r= 0; fls->max= fls->dglen+1;
  88   }
  89   if (labstart_r) *labstart_r= fls->cbyte;
  90   if (lablen) {
  91     if (fls->namelen) fls->namelen++;
  92     fls->namelen+= lablen;
  93     if (fls->namelen > DNS_MAXDOMAIN) return adns_s_domaintoolong;
  94     fls->cbyte+= lablen;
  95     if (fls->cbyte > fls->dglen) goto x_truncated;
  96     if (fls->cbyte > fls->max) goto x_serverfaulty;
  97   } else {
  98     if (fls->dmend_r) *(fls->dmend_r)= fls->cbyte;
  99   }
 100   *lablen_r= lablen;
 101 /*if (labstart_r) fprintf(stderr,"label %d >%.*s<\n",lablen,lablen,fls->dgram+*labstart_r);*/
 102   return adns_s_ok;
 103
 104  x_truncated:
 105   *lablen_r= -1;
 106   return adns_s_ok;
 107
 108  x_serverfaulty:
 109   adns__diag(fls->ads,fls->serv,fls->qu,"label in domain runs beyond end of domain");
 110   return adns_s_serverfaulty;
 111 }
 112
 113 adns_status adns__parse_domain(adns_state ads, int serv, adns_query qu,
 114                                vbuf *vb, int flags,
 115                                const byte *dgram, int dglen, int *cbyte_io, int max) {
 116   findlabel_state fls;
 117
 118   int lablen, labstart, i, ch;
 119   adns_status st;
 120
 121   adns__findlabel_start(&fls,ads, serv,qu, dgram,dglen,max, *cbyte_io,cbyte_io);
 122   vb->used= 0;
 123   for (;;) {
 124     st= adns__findlabel_next(&fls,&lablen,&labstart);
 125     if (st) return st;
 126     if (lablen<0) { vb->used=0; return adns_s_ok; }
 127     if (!lablen) break;
 128     if (vb->used)
 129       if (!adns__vbuf_append(vb,".",1)) return adns_s_nolocalmem;
 130     if (flags & adns_qf_anyquote) {
 131       if (!vbuf__append_quoted1035(vb,dgram+labstart,lablen))
 132         return adns_s_nolocalmem;
 133     } else {
 134       ch= dgram[labstart];
 135       if (!ctype_alpha(ch) && !ctype_digit(ch)) return adns_s_invalidanswerdomain;
 136       for (i= labstart+1; i<labstart+lablen; i++) {
 137         ch= dgram[i];
 138         if (ch != '-' && !ctype_alpha(ch) && !ctype_digit(ch))
 139           return adns_s_invalidanswerdomain;
 140       }
 141       if (!adns__vbuf_append(vb,dgram+labstart,lablen))
 142         return adns_s_nolocalmem;
 143     }
 144   }
 145   if (!adns__vbuf_append(vb,"",1)) return adns_s_nolocalmem;
 146   return adns_s_ok;
 147 }
 148
 149 static adns_status findrr_intern(adns_query qu, int serv,
 150                                  const byte *dgram, int dglen, int *cbyte_io,
 151                                  int *type_r, int *class_r, int *rdlen_r, int *rdstart_r,
 152                                  const byte *eo_dgram, int eo_dglen, int eo_cbyte,
 153                                  int *eo_matched_r) {
 154   /* Like adns__findrr_checked, except that the datagram to compare
 155    * with can be specified explicitly.
 156    *
 157    * If the caller thinks they know what the owner of the RR ought to
 158    * be they can pass in details in eo_*: this is another (or perhaps
 159    * the same datagram), and a pointer to where the putative owner
 160    * starts in that datagram.  In this case *eo_matched_r will be set
 161    * to 1 if the datagram matched or 0 if it did not.  Either
 162    * both eo_dgram and eo_matched_r must both be non-null, or they
 163    * must both be null (in which case eo_dglen and eo_cbyte will be ignored).
 164    * The eo datagram and contained owner domain MUST be valid and
 165    * untruncated.
 166    */
 167   findlabel_state fls, eo_fls;
 168   int cbyte;
 169
 170   int tmp, rdlen, mismatch;
 171   int lablen, labstart, ch;
 172   int eo_lablen, eo_labstart, eo_ch;
 173   adns_status st;
 174
 175   cbyte= *cbyte_io;
 176
 177   adns__findlabel_start(&fls,qu->ads, serv,qu, dgram,dglen,dglen,cbyte,&cbyte);
 178   if (eo_dgram) {
 179     adns__findlabel_start(&eo_fls,qu->ads, -1,0, eo_dgram,eo_dglen,eo_dglen,eo_cbyte,0);
 180     mismatch= 0;
 181   } else {
 182     mismatch= 1;
 183   }
 184
 185   for (;;) {
 186     st= adns__findlabel_next(&fls,&lablen,&labstart);
 187     if (st) return st;
 188     if (lablen<0) goto x_truncated;
 189
 190     if (!mismatch) {
 191       st= adns__findlabel_next(&eo_fls,&eo_lablen,&eo_labstart);
 192       assert(!st); assert(eo_lablen>=0);
 193       if (lablen != eo_lablen) mismatch= 1;
 194       while (!mismatch && eo_lablen-- > 0) {
 195         ch= dgram[labstart++]; if (ctype_alpha(ch)) ch &= ~32;
 196         eo_ch= eo_dgram[eo_labstart++]; if (ctype_alpha(eo_ch)) eo_ch &= ~32;
 197         if (ch != eo_ch) mismatch= 1;
 198       }
 199     }
 200     if (!lablen) break;
 201   }
 202   if (eo_matched_r) *eo_matched_r= !mismatch;
 203
 204   if (cbyte+10>dglen) goto x_truncated;
 205   GET_W(cbyte,tmp); *type_r= tmp;
 206   GET_W(cbyte,tmp); *class_r= tmp;
 207   cbyte+= 4; /* we skip the TTL */
 208   GET_W(cbyte,rdlen); if (rdlen_r) *rdlen_r= rdlen;
 209   if (rdstart_r) *rdstart_r= cbyte;
 210   cbyte+= rdlen;
 211   if (cbyte>dglen) goto x_truncated;
 212   *cbyte_io= cbyte;
 213   return adns_s_ok;
 214
 215  x_truncated:
 216   *type_r= -1;
 217   return 0;
 218 }
 219
 220 adns_status adns__findrr(adns_query qu, int serv,
 221                          const byte *dgram, int dglen, int *cbyte_io,
 222                          int *type_r, int *class_r, int *rdlen_r, int *rdstart_r,
 223                          int *ownermatchedquery_r) {
 224   if (!ownermatchedquery_r) {
 225     return findrr_intern(qu,serv,
 226                          dgram,dglen,cbyte_io,
 227                          type_r,class_r,rdlen_r,rdstart_r,
 228                          0,0,0, 0);
 229   } else if (!qu->cname_dgram) {
 230     return findrr_intern(qu,serv,
 231                          dgram,dglen,cbyte_io,
 232                          type_r,class_r,rdlen_r,rdstart_r,
 233                          qu->query_dgram,qu->query_dglen,DNS_HDRSIZE,
 234                          ownermatchedquery_r);
 235   } else {
 236     return findrr_intern(qu,serv,
 237                          dgram,dglen,cbyte_io,
 238                          type_r,class_r,rdlen_r,rdstart_r,
 239                          qu->cname_dgram,qu->cname_dglen,qu->cname_begin,
 240                          ownermatchedquery_r);
 241   }
 242 }