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
   7  *    Copyright (C) 1997-2000,2003,2006,2014  Ian Jackson
   8  *    Copyright (C) 1999-2000,2003,2006  Tony Finch
   9  *    Copyright (C) 1991 Massachusetts Institute of Technology
  10  *  (See the file INSTALL for full details.)
  11  *
  12  *  This program is free software; you can redistribute it and/or modify
  13  *  it under the terms of the GNU General Public License as published by
  14  *  the Free Software Foundation; either version 3, or (at your option)
  15  *  any later version.
  16  *
  17  *  This program is distributed in the hope that it will be useful,
  18  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20  *  GNU General Public License for more details.
  21  *
  22  *  You should have received a copy of the GNU General Public License
  23  *  along with this program; if not, write to the Free Software Foundation.
  24  */
  25
  26 #include "internal.h"
  27
  28 int vbuf__append_quoted1035(vbuf *vb, const byte *buf, int len) {
  29   char qbuf[10];
  30   int i, ch;
  31
  32   while (len) {
  33     qbuf[0]= 0;
  34     for (i=0; i<len; i++) {
  35       ch= buf[i];
  36       if (ch <= ' ' || ch >= 127) {
  37         sprintf(qbuf,"\\%03o",ch);
  38         break;
  39       } else if (!ctype_domainunquoted(ch)) {
  40         sprintf(qbuf,"\\%c",ch);
  41         break;
  42       }
  43     }
  44     if (!adns__vbuf_append(vb,buf,i) ||
  45         !adns__vbuf_append(vb,qbuf,strlen(qbuf)))
  46       return 0;
  47     if (i<len) i++;
  48     buf+= i;
  49     len-= i;
  50   }
  51   return 1;
  52 }
  53
  54 void adns__findlabel_start(findlabel_state *fls, adns_state ads,
  55                            int serv, adns_query qu,
  56                            const byte *dgram, int dglen, int max,
  57                            int dmbegin, int *dmend_rlater) {
  58   fls->ads= ads;
  59   fls->qu= qu;
  60   fls->serv= serv;
  61   fls->dgram= dgram;
  62   fls->dglen= dglen;
  63   fls->max= max;
  64   fls->cbyte= dmbegin;
  65   fls->namelen= 0;
  66   fls->dmend_r= dmend_rlater;
  67 }
  68
  69 adns_status adns__findlabel_next(findlabel_state *fls,
  70                                  int *lablen_r, int *labstart_r) {
  71   int lablen, jumpto;
  72   const char *dgram;
  73
  74   dgram= fls->dgram;
  75   for (;;) {
  76     if (fls->cbyte >= fls->dglen) goto x_truncated;
  77     if (fls->cbyte >= fls->max) goto x_badresponse;
  78     GET_B(fls->cbyte,lablen);
  79     if (!(lablen & 0x0c0)) break;
  80     if ((lablen & 0x0c0) != 0x0c0) return adns_s_unknownformat;
  81     if (fls->cbyte >= fls->dglen) goto x_truncated;
  82     if (fls->cbyte >= fls->max) goto x_badresponse;
  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_answerdomaintoolong;
  94     fls->cbyte+= lablen;
  95     if (fls->cbyte > fls->dglen) goto x_truncated;
  96     if (fls->cbyte > fls->max) goto x_badresponse;
  97   } else {
  98     if (fls->dmend_r) *(fls->dmend_r)= fls->cbyte;
  99   }
 100   *lablen_r= lablen;
 101   return adns_s_ok;
 102
 103  x_truncated:
 104   *lablen_r= -1;
 105   return adns_s_ok;
 106
 107  x_badresponse:
 108   adns__diag(fls->ads,fls->serv,fls->qu,
 109              "label in domain runs beyond end of domain");
 110   return adns_s_invalidresponse;
 111 }
 112
 113 adns_status adns__parse_domain(adns_state ads, int serv, adns_query qu,
 114                                vbuf *vb, parsedomain_flags flags,
 115                                const byte *dgram, int dglen, int *cbyte_io,
 116                                int max) {
 117   findlabel_state fls;
 118
 119   adns__findlabel_start(&fls,ads, serv,qu, dgram,dglen,max,
 120                         *cbyte_io,cbyte_io);
 121   vb->used= 0;
 122   return adns__parse_domain_more(&fls,ads,qu, vb,flags,dgram);
 123 }
 124
 125 adns_status adns__parse_domain_more(findlabel_state *fls, adns_state ads,
 126                                     adns_query qu, vbuf *vb,
 127                                     parsedomain_flags flags,
 128                                     const byte *dgram) {
 129   int lablen, labstart, i, ch, first;
 130   adns_status st;
 131
 132   first= 1;
 133   for (;;) {
 134     st= adns__findlabel_next(fls,&lablen,&labstart);
 135     if (st) return st;
 136     if (lablen<0) { vb->used=0; return adns_s_ok; }
 137     if (!lablen) break;
 138     if (first) {
 139       first= 0;
 140     } else {
 141       if (!adns__vbuf_append(vb,".",1)) return adns_s_nomemory;
 142     }
 143     if (flags & pdf_quoteok) {
 144       if (!vbuf__append_quoted1035(vb,dgram+labstart,lablen))
 145         return adns_s_nomemory;
 146     } else {
 147       ch= dgram[labstart];
 148       if (!ctype_alpha(ch) && !ctype_digit(ch))
 149         return adns_s_answerdomaininvalid;
 150       for (i= labstart+1; i<labstart+lablen; i++) {
 151         ch= dgram[i];
 152         if (ch != '-' && !ctype_alpha(ch) && !ctype_digit(ch))
 153           return adns_s_answerdomaininvalid;
 154       }
 155       if (!adns__vbuf_append(vb,dgram+labstart,lablen))
 156         return adns_s_nomemory;
 157     }
 158   }
 159   if (!adns__vbuf_append(vb,"",1)) return adns_s_nomemory;
 160   return adns_s_ok;
 161 }
 162
 163 bool adns__labels_equal(const byte *a, int al, const byte *b, int bl) {
 164   if (al != bl) return 0;
 165   while (al-- > 0) {
 166     int ac= ctype_toupper(*a++);
 167     int bc= ctype_toupper(*b++);
 168     if (ac != bc) return 0;
 169   }
 170   return 1;
 171 }
 172
 173 adns_status adns__findrr_anychk(adns_query qu, int serv,
 174                                 const byte *dgram, int dglen, int *cbyte_io,
 175                                 int *type_r, int *class_r,
 176                                 unsigned long *ttl_r,
 177                                 int *rdlen_r, int *rdstart_r,
 178                                 const byte *eo_dgram, int eo_dglen,
 179                                 int eo_cbyte, int *eo_matched_r) {
 180   findlabel_state fls, eo_fls_buf;
 181   findlabel_state *eo_fls; /* 0 iff we know it's not matching eo_... */
 182   int cbyte;
 183
 184   int tmp, rdlen;
 185   unsigned long ttl;
 186   int lablen, labstart;
 187   int eo_lablen, eo_labstart;
 188   adns_status st;
 189
 190   cbyte= *cbyte_io;
 191
 192   adns__findlabel_start(&fls,qu->ads, serv,qu, dgram,dglen,dglen,cbyte,&cbyte);
 193   if (eo_dgram) {
 194     eo_fls= &eo_fls_buf;
 195     adns__findlabel_start(eo_fls,qu->ads, -1,0,
 196                           eo_dgram,eo_dglen,eo_dglen,eo_cbyte,0);
 197   } else {
 198     eo_fls= 0;
 199   }
 200
 201   for (;;) {
 202     st= adns__findlabel_next(&fls,&lablen,&labstart);
 203     if (st) return st;
 204     if (lablen<0) goto x_truncated;
 205
 206     if (eo_fls) {
 207       st= adns__findlabel_next(eo_fls,&eo_lablen,&eo_labstart);
 208       assert(!st); assert(eo_lablen>=0);
 209       if (!adns__labels_equal(dgram+labstart, lablen,
 210                               eo_dgram+eo_labstart, eo_lablen))
 211         eo_fls= 0;
 212     }
 213     if (!lablen) break;
 214   }
 215   if (eo_matched_r) *eo_matched_r= !!eo_fls;
 216
 217   if (cbyte+10>dglen) goto x_truncated;
 218   GET_W(cbyte,tmp); *type_r= tmp;
 219   GET_W(cbyte,tmp); *class_r= tmp;
 220
 221   GET_L(cbyte,ttl);
 222   if (ttl > MAXTTLBELIEVE) ttl= MAXTTLBELIEVE;
 223   *ttl_r= ttl;
 224
 225   GET_W(cbyte,rdlen); if (rdlen_r) *rdlen_r= rdlen;
 226   if (rdstart_r) *rdstart_r= cbyte;
 227   cbyte+= rdlen;
 228   if (cbyte>dglen) goto x_truncated;
 229   *cbyte_io= cbyte;
 230   return adns_s_ok;
 231
 232  x_truncated:
 233   *type_r= -1;
 234   return 0;
 235 }
 236
 237 adns_status adns__findrr(adns_query qu, int serv,
 238                          const byte *dgram, int dglen, int *cbyte_io,
 239                          int *type_r, int *class_r, unsigned long *ttl_r,
 240                          int *rdlen_r, int *rdstart_r,
 241                          int *ownermatchedquery_r) {
 242   if (!ownermatchedquery_r) {
 243     return adns__findrr_anychk(qu,serv,
 244                                dgram,dglen,cbyte_io,
 245                                type_r,class_r,ttl_r,rdlen_r,rdstart_r,
 246                                0,0,0, 0);
 247   } else if (!qu->cname_dgram) {
 248     return adns__findrr_anychk(qu,serv,
 249                                dgram,dglen,cbyte_io,
 250                                type_r,class_r,ttl_r,rdlen_r,rdstart_r,
 251                                qu->query_dgram,qu->query_dglen,DNS_HDRSIZE,
 252                                ownermatchedquery_r);
 253   } else {
 254     return adns__findrr_anychk(qu,serv,
 255                                dgram,dglen,cbyte_io,
 256                                type_r,class_r,ttl_r,rdlen_r,rdstart_r,
 257                                qu->cname_dgram,qu->cname_dglen,qu->cname_begin,
 258                                ownermatchedquery_r);
 259   }
 260 }