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) 1997-2000,2003,2006,2014-2016  Ian Jackson
   8  *    Copyright (C) 2014  Mark Wooding
   9  *    Copyright (C) 1999-2000,2003,2006  Tony Finch
  10  *    Copyright (C) 1991 Massachusetts Institute of Technology
  11  *  (See the file INSTALL for full details.)
  12  *
  13  *  This program is free software; you can redistribute it and/or modify
  14  *  it under the terms of the GNU General Public License as published by
  15  *  the Free Software Foundation; either version 3, or (at your option)
  16  *  any later version.
  17  *
  18  *  This program is distributed in the hope that it will be useful,
  19  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  *  GNU General Public License for more details.
  22  *
  23  *  You should have received a copy of the GNU General Public License
  24  *  along with this program; if not, write to the Free Software Foundation.
  25  */
  26
  27 #include "internal.h"
  28
  29 static int vbuf_append_quoted1035(vbuf *vb, const byte *buf, int len) {
  30   char qbuf[10];
  31   int i, ch;
  32
  33   while (len) {
  34     qbuf[0]= 0;
  35     for (i=0; i<len; i++) {
  36       ch= buf[i];
  37       if (ch <= ' ' || ch >= 127) {
  38         sprintf(qbuf,"\\%03o",ch);
  39         break;
  40       } else if (!ctype_domainunquoted(ch)) {
  41         sprintf(qbuf,"\\%c",ch);
  42         break;
  43       }
  44     }
  45     if (!adns__vbuf_append(vb,buf,i) ||
  46         !adns__vbuf_append(vb,qbuf,strlen(qbuf)))
  47       return 0;
  48     if (i<len) i++;
  49     buf+= i;
  50     len-= i;
  51   }
  52   return 1;
  53 }
  54
  55 void adns__findlabel_start(findlabel_state *fls, adns_state ads,
  56                            int serv, adns_query qu,
  57                            const byte *dgram, int dglen, int max,
  58                            int dmbegin, int *dmend_rlater) {
  59   fls->ads= ads;
  60   fls->qu= qu;
  61   fls->serv= serv;
  62   fls->dgram= dgram;
  63   fls->dglen= dglen;
  64   fls->max= max;
  65   fls->cbyte= dmbegin;
  66   fls->namelen= 0;
  67   fls->dmend_r= dmend_rlater;
  68 }
  69
  70 adns_status adns__findlabel_next(findlabel_state *fls,
  71                                  int *lablen_r, int *labstart_r) {
  72   int lablen, jumpto;
  73   const char *dgram;
  74
  75   dgram= fls->dgram;
  76   for (;;) {
  77     if (fls->cbyte >= fls->dglen) goto x_truncated;
  78     if (fls->cbyte >= fls->max) goto x_badresponse;
  79     GET_B(fls->cbyte,lablen);
  80     if (!(lablen & 0x0c0)) break;
  81     if ((lablen & 0x0c0) != 0x0c0) return adns_s_unknownformat;
  82     if (fls->cbyte >= fls->dglen) goto x_truncated;
  83     if (fls->cbyte >= fls->max) goto x_badresponse;
  84     GET_B(fls->cbyte,jumpto);
  85     jumpto |= (lablen&0x3f)<<8;
  86     if (fls->dmend_r) *(fls->dmend_r)= fls->cbyte;
  87     fls->cbyte= jumpto;
  88     fls->dmend_r= 0; fls->max= fls->dglen+1;
  89   }
  90   if (labstart_r) *labstart_r= fls->cbyte;
  91   if (lablen) {
  92     if (fls->namelen) fls->namelen++;
  93     fls->namelen+= lablen;
  94     if (fls->namelen > DNS_MAXDOMAIN) return adns_s_answerdomaintoolong;
  95     fls->cbyte+= lablen;
  96     if (fls->cbyte > fls->dglen) goto x_truncated;
  97     if (fls->cbyte > fls->max) goto x_badresponse;
  98   } else {
  99     if (fls->dmend_r) *(fls->dmend_r)= fls->cbyte;
 100   }
 101   *lablen_r= lablen;
 102   return adns_s_ok;
 103
 104  x_truncated:
 105   *lablen_r= -1;
 106   return adns_s_ok;
 107
 108  x_badresponse:
 109   adns__diag(fls->ads,fls->serv,fls->qu,
 110              "label in domain runs beyond end of domain");
 111   return adns_s_invalidresponse;
 112 }
 113
 114 adns_status adns__parse_domain(adns_state ads, int serv, adns_query qu,
 115                                vbuf *vb, parsedomain_flags flags,
 116                                const byte *dgram, int dglen, int *cbyte_io,
 117                                int max) {
 118   findlabel_state fls;
 119
 120   adns__findlabel_start(&fls,ads, serv,qu, dgram,dglen,max,
 121                         *cbyte_io,cbyte_io);
 122   vb->used= 0;
 123   return adns__parse_domain_more(&fls,ads,qu, vb,flags,dgram);
 124 }
 125
 126 adns_status adns__parse_domain_more(findlabel_state *fls, adns_state ads,
 127                                     adns_query qu, vbuf *vb,
 128                                     parsedomain_flags flags,
 129                                     const byte *dgram) {
 130   int lablen, labstart, i, ch, first;
 131   adns_status st;
 132
 133   first= 1;
 134   for (;;) {
 135     st= adns__findlabel_next(fls,&lablen,&labstart);
 136     if (st) return st;
 137     if (lablen<0) { vb->used=0; return adns_s_ok; }
 138     if (!lablen) break;
 139     if (first) {
 140       first= 0;
 141     } else {
 142       if (!adns__vbuf_append(vb,".",1)) return adns_s_nomemory;
 143     }
 144     if (flags & pdf_quoteok) {
 145       if (!vbuf_append_quoted1035(vb,dgram+labstart,lablen))
 146         return adns_s_nomemory;
 147     } else {
 148       ch= dgram[labstart];
 149       if (!ctype_alpha(ch) && !ctype_digit(ch))
 150         return adns_s_answerdomaininvalid;
 151       for (i= labstart+1; i<labstart+lablen; i++) {
 152         ch= dgram[i];
 153         if (ch != '-' && !ctype_alpha(ch) && !ctype_digit(ch))
 154           return adns_s_answerdomaininvalid;
 155       }
 156       if (!adns__vbuf_append(vb,dgram+labstart,lablen))
 157         return adns_s_nomemory;
 158     }
 159   }
 160   if (!adns__vbuf_append(vb,"",1)) return adns_s_nomemory;
 161   return adns_s_ok;
 162 }
 163
 164 bool adns__labels_equal(const byte *a, int al, const byte *b, int bl) {
 165   if (al != bl) return 0;
 166   while (al-- > 0) {
 167     int ac= ctype_toupper(*a++);
 168     int bc= ctype_toupper(*b++);
 169     if (ac != bc) return 0;
 170   }
 171   return 1;
 172 }
 173
 174 adns_status adns__findrr_anychk(adns_query qu, int serv,
 175                                 const byte *dgram, int dglen, int *cbyte_io,
 176                                 int *type_r, int *class_r,
 177                                 unsigned long *ttl_r,
 178                                 int *rdlen_r, int *rdstart_r,
 179                                 const byte *eo_dgram, int eo_dglen,
 180                                 int eo_cbyte, int *eo_matched_r) {
 181   findlabel_state fls, eo_fls_buf;
 182   findlabel_state *eo_fls; /* 0 iff we know it's not matching eo_... */
 183   int cbyte;
 184
 185   int tmp, rdlen;
 186   unsigned long ttl;
 187   int lablen, labstart;
 188   int eo_lablen, eo_labstart;
 189   adns_status st;
 190
 191   cbyte= *cbyte_io;
 192
 193   adns__findlabel_start(&fls,qu->ads, serv,qu, dgram,dglen,dglen,cbyte,&cbyte);
 194   if (eo_dgram) {
 195     eo_fls= &eo_fls_buf;
 196     adns__findlabel_start(eo_fls,qu->ads, -1,0,
 197                           eo_dgram,eo_dglen,eo_dglen,eo_cbyte,0);
 198   } else {
 199     eo_fls= 0;
 200   }
 201
 202   for (;;) {
 203     st= adns__findlabel_next(&fls,&lablen,&labstart);
 204     if (st) return st;
 205     if (lablen<0) goto x_truncated;
 206
 207     if (eo_fls) {
 208       st= adns__findlabel_next(eo_fls,&eo_lablen,&eo_labstart);
 209       assert(!st); assert(eo_lablen>=0);
 210       if (!adns__labels_equal(dgram+labstart, lablen,
 211                               eo_dgram+eo_labstart, eo_lablen))
 212         eo_fls= 0;
 213     }
 214     if (!lablen) break;
 215   }
 216   if (eo_matched_r) *eo_matched_r= !!eo_fls;
 217
 218   if (cbyte+10>dglen) goto x_truncated;
 219   GET_W(cbyte,tmp); *type_r= tmp;
 220   GET_W(cbyte,tmp); *class_r= tmp;
 221
 222   GET_L(cbyte,ttl);
 223   if (ttl > MAXTTLBELIEVE) ttl= MAXTTLBELIEVE;
 224   *ttl_r= ttl;
 225
 226   GET_W(cbyte,rdlen); if (rdlen_r) *rdlen_r= rdlen;
 227   if (rdstart_r) *rdstart_r= cbyte;
 228   cbyte+= rdlen;
 229   if (cbyte>dglen) goto x_truncated;
 230   *cbyte_io= cbyte;
 231   return adns_s_ok;
 232
 233  x_truncated:
 234   *type_r= -1;
 235   return 0;
 236 }
 237
 238 adns_status adns__findrr(adns_query qu, int serv,
 239                          const byte *dgram, int dglen, int *cbyte_io,
 240                          int *type_r, int *class_r, unsigned long *ttl_r,
 241                          int *rdlen_r, int *rdstart_r,
 242                          int *ownermatchedquery_r) {
 243   if (!ownermatchedquery_r) {
 244     return adns__findrr_anychk(qu,serv,
 245                                dgram,dglen,cbyte_io,
 246                                type_r,class_r,ttl_r,rdlen_r,rdstart_r,
 247                                0,0,0, 0);
 248   } else if (!qu->cname_dgram) {
 249     return adns__findrr_anychk(qu,serv,
 250                                dgram,dglen,cbyte_io,
 251                                type_r,class_r,ttl_r,rdlen_r,rdstart_r,
 252                                qu->query_dgram,qu->query_dglen,DNS_HDRSIZE,
 253                                ownermatchedquery_r);
 254   } else {
 255     return adns__findrr_anychk(qu,serv,
 256                                dgram,dglen,cbyte_io,
 257                                type_r,class_r,ttl_r,rdlen_r,rdstart_r,
 258                                qu->cname_dgram,qu->cname_dglen,qu->cname_begin,
 259                                ownermatchedquery_r);
 260   }
 261 }