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 Ian Jackson
   7  *  and contributors (see the file INSTALL for full details).
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License as published by
  11  *  the Free Software Foundation; either version 3, or (at your option)
  12  *  any later version.
  13  *
  14  *  This program is distributed in the hope that it will be useful,
  15  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  *  GNU General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License
  20  *  along with this program; if not, write to the Free Software Foundation.
  21  */
  22
  23 #include "internal.h"
  24
  25 static 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 >= 127) {
  34         sprintf(qbuf,"\\%03o",ch);
  35         break;
  36       } else if (!ctype_domainunquoted(ch)) {
  37         sprintf(qbuf,"\\%c",ch);
  38         break;
  39       }
  40     }
  41     if (!adns__vbuf_append(vb,buf,i) ||
  42         !adns__vbuf_append(vb,qbuf,strlen(qbuf)))
  43       return 0;
  44     if (i<len) i++;
  45     buf+= i;
  46     len-= i;
  47   }
  48   return 1;
  49 }
  50
  51 void adns__findlabel_start(findlabel_state *fls, adns_state ads,
  52                            int serv, adns_query qu,
  53                            const byte *dgram, int dglen, int max,
  54                            int dmbegin, int *dmend_rlater) {
  55   fls->ads= ads;
  56   fls->qu= qu;
  57   fls->serv= serv;
  58   fls->dgram= dgram;
  59   fls->dglen= dglen;
  60   fls->max= max;
  61   fls->cbyte= dmbegin;
  62   fls->namelen= 0;
  63   fls->dmend_r= dmend_rlater;
  64 }
  65
  66 adns_status adns__findlabel_next(findlabel_state *fls,
  67                                  int *lablen_r, int *labstart_r) {
  68   int lablen, jumpto;
  69   const char *dgram;
  70   int had_pointer= 0;
  71
  72   dgram= fls->dgram;
  73   for (;;) {
  74     if (fls->cbyte >= fls->dglen) goto x_truncated;
  75     if (fls->cbyte >= fls->max) goto x_badresponse;
  76     GET_B(fls->cbyte,lablen);
  77     if (!(lablen & 0x0c0)) break;
  78     if ((lablen & 0x0c0) != 0x0c0) return adns_s_unknownformat;
  79     if (fls->cbyte >= fls->dglen) goto x_truncated;
  80     if (fls->cbyte >= fls->max) goto x_badresponse;
  81     if (had_pointer++ >= 2) goto x_loop;
  82     GET_B(fls->cbyte,jumpto);
  83     jumpto |= (lablen&0x3f)<<8;
  84     if (fls->dmend_r) *(fls->dmend_r)= fls->cbyte;
  85     fls->cbyte= jumpto;
  86     fls->dmend_r= 0; fls->max= fls->dglen+1;
  87   }
  88   if (labstart_r) *labstart_r= fls->cbyte;
  89   if (lablen) {
  90     if (fls->namelen) fls->namelen++;
  91     fls->namelen+= lablen;
  92     if (fls->namelen > DNS_MAXDOMAIN) return adns_s_answerdomaintoolong;
  93     fls->cbyte+= lablen;
  94     if (fls->cbyte > fls->dglen) goto x_truncated;
  95     if (fls->cbyte > fls->max) goto x_badresponse;
  96   } else {
  97     if (fls->dmend_r) *(fls->dmend_r)= fls->cbyte;
  98   }
  99   *lablen_r= lablen;
 100   return adns_s_ok;
 101
 102  x_truncated:
 103   *lablen_r= -1;
 104   return adns_s_ok;
 105
 106  x_badresponse:
 107   adns__diag(fls->ads,fls->serv,fls->qu,
 108              "label in domain runs or points outside of packet");
 109   return adns_s_invalidresponse;
 110
 111  x_loop:
 112   adns__diag(fls->ads,fls->serv,fls->qu,
 113              "compressed label pointer chain");
 114   return adns_s_invalidresponse;
 115 }
 116
 117 adns_status adns__parse_domain(adns_state ads, int serv, adns_query qu,
 118                                vbuf *vb, parsedomain_flags flags,
 119                                const byte *dgram, int dglen, int *cbyte_io,
 120                                int max) {
 121   findlabel_state fls;
 122
 123   adns__findlabel_start(&fls,ads, serv,qu, dgram,dglen,max,
 124                         *cbyte_io,cbyte_io);
 125   vb->used= 0;
 126   return adns__parse_domain_more(&fls,ads,qu, vb,flags,dgram);
 127 }
 128
 129 adns_status adns__parse_domain_more(findlabel_state *fls, adns_state ads,
 130                                     adns_query qu, vbuf *vb,
 131                                     parsedomain_flags flags,
 132                                     const byte *dgram) {
 133   int lablen, labstart, i, ch, first;
 134   adns_status st;
 135
 136   first= 1;
 137   for (;;) {
 138     st= adns__findlabel_next(fls,&lablen,&labstart);
 139     if (st) return st;
 140     if (lablen<0) { vb->used=0; return adns_s_ok; }
 141     if (!lablen) break;
 142     if (first) {
 143       first= 0;
 144     } else {
 145       if (!adns__vbuf_append(vb,".",1)) return adns_s_nomemory;
 146     }
 147     if (flags & pdf_quoteok) {
 148       if (!vbuf_append_quoted1035(vb,dgram+labstart,lablen))
 149         return adns_s_nomemory;
 150     } else {
 151       ch= dgram[labstart];
 152       if (!ctype_alpha(ch) && !ctype_digit(ch))
 153         return adns_s_answerdomaininvalid;
 154       for (i= labstart+1; i<labstart+lablen; i++) {
 155         ch= dgram[i];
 156         if (ch != '-' && !ctype_alpha(ch) && !ctype_digit(ch))
 157           return adns_s_answerdomaininvalid;
 158       }
 159       if (!adns__vbuf_append(vb,dgram+labstart,lablen))
 160         return adns_s_nomemory;
 161     }
 162   }
 163   if (!adns__vbuf_append(vb,"",1)) return adns_s_nomemory;
 164   return adns_s_ok;
 165 }
 166
 167 bool adns__labels_equal(const byte *a, int al, const byte *b, int bl) {
 168   if (al != bl) return 0;
 169   while (al-- > 0) {
 170     int ac= ctype_toupper(*a++);
 171     int bc= ctype_toupper(*b++);
 172     if (ac != bc) return 0;
 173   }
 174   return 1;
 175 }
 176
 177 adns_status adns__findrr_anychk(adns_query qu, int serv,
 178                                 const byte *dgram, int dglen, int *cbyte_io,
 179                                 int *type_r, int *class_r,
 180                                 unsigned long *ttl_r,
 181                                 int *rdlen_r, int *rdstart_r,
 182                                 const byte *eo_dgram, int eo_dglen,
 183                                 int eo_cbyte, int *eo_matched_r) {
 184   findlabel_state fls, eo_fls_buf;
 185   findlabel_state *eo_fls; /* 0 iff we know it's not matching eo_... */
 186   int cbyte;
 187
 188   int tmp, rdlen;
 189   unsigned long ttl;
 190   int lablen, labstart;
 191   int eo_lablen, eo_labstart;
 192   adns_status st;
 193
 194   cbyte= *cbyte_io;
 195
 196   adns__findlabel_start(&fls,qu->ads, serv,qu, dgram,dglen,dglen,cbyte,&cbyte);
 197   if (eo_dgram) {
 198     eo_fls= &eo_fls_buf;
 199     adns__findlabel_start(eo_fls,qu->ads, -1,0,
 200                           eo_dgram,eo_dglen,eo_dglen,eo_cbyte,0);
 201   } else {
 202     eo_fls= 0;
 203   }
 204
 205   for (;;) {
 206     st= adns__findlabel_next(&fls,&lablen,&labstart);
 207     if (st) return st;
 208     if (lablen<0) goto x_truncated;
 209
 210     if (eo_fls) {
 211       st= adns__findlabel_next(eo_fls,&eo_lablen,&eo_labstart);
 212       assert(!st); assert(eo_lablen>=0);
 213       if (!adns__labels_equal(dgram+labstart, lablen,
 214                               eo_dgram+eo_labstart, eo_lablen))
 215         eo_fls= 0;
 216     }
 217     if (!lablen) break;
 218   }
 219   if (eo_matched_r) *eo_matched_r= !!eo_fls;
 220
 221   if (cbyte+10>dglen) goto x_truncated;
 222   GET_W(cbyte,tmp); *type_r= tmp;
 223   GET_W(cbyte,tmp); *class_r= tmp;
 224
 225   GET_L(cbyte,ttl);
 226   if (ttl > MAXTTLBELIEVE) ttl= MAXTTLBELIEVE;
 227   *ttl_r= ttl;
 228
 229   GET_W(cbyte,rdlen); if (rdlen_r) *rdlen_r= rdlen;
 230   if (rdstart_r) *rdstart_r= cbyte;
 231   cbyte+= rdlen;
 232   if (cbyte>dglen) goto x_truncated;
 233   *cbyte_io= cbyte;
 234   return adns_s_ok;
 235
 236  x_truncated:
 237   *type_r= -1;
 238   return 0;
 239 }
 240
 241 adns_status adns__findrr(adns_query qu, int serv,
 242                          const byte *dgram, int dglen, int *cbyte_io,
 243                          int *type_r, int *class_r, unsigned long *ttl_r,
 244                          int *rdlen_r, int *rdstart_r,
 245                          int *ownermatchedquery_r) {
 246   if (!ownermatchedquery_r) {
 247     return adns__findrr_anychk(qu,serv,
 248                                dgram,dglen,cbyte_io,
 249                                type_r,class_r,ttl_r,rdlen_r,rdstart_r,
 250                                0,0,0, 0);
 251   } else if (!qu->cname_dgram) {
 252     return adns__findrr_anychk(qu,serv,
 253                                dgram,dglen,cbyte_io,
 254                                type_r,class_r,ttl_r,rdlen_r,rdstart_r,
 255                                qu->query_dgram,qu->query_dglen,DNS_HDRSIZE,
 256                                ownermatchedquery_r);
 257   } else {
 258     return adns__findrr_anychk(qu,serv,
 259                                dgram,dglen,cbyte_io,
 260                                type_r,class_r,ttl_r,rdlen_r,rdstart_r,
 261                                qu->cname_dgram,qu->cname_dglen,qu->cname_begin,
 262                                ownermatchedquery_r);
 263   }
 264 }