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

   1 /**/
   2
   3 #include "internal.h"
   4
   5 int vbuf__append_quoted1035(vbuf *vb, const byte *buf, int len) {
   6   char qbuf[10];
   7   int i, ch;
   8
   9   while (len) {
  10     qbuf[0]= 0;
  11     for (i=0; i<len; i++) {
  12       ch= buf[i];
  13       if (ch == '.' || ch == '"' || ch == '(' || ch == ')' ||
  14           ch == '@' || ch == ';' || ch == '$') {
  15         sprintf(qbuf,"\\%c",ch);
  16         break;
  17       } else if (ch <= ' ' || ch >= 127) {
  18         sprintf(qbuf,"\\%03o",ch);
  19         break;
  20       }
  21     }
  22     if (!adns__vbuf_append(vb,buf,i) || !adns__vbuf_append(vb,qbuf,strlen(qbuf)))
  23       return 0;
  24     buf+= i; len-= i;
  25   }
  26   return 1;
  27 }
  28
  29 void adns__findlabel_start(findlabel_state *fls,
  30                            adns_state ads, int serv,
  31                            const byte *dgram, int dglen, int max,
  32                            int dmbegin, int *dmend_rlater) {
  33   fls->ads= ads;
  34   fls->serv= serv;
  35   fls->dgram= dgram;
  36   fls->dglen= dglen;
  37   fls->max= max;
  38   fls->cbyte= dmbegin;
  39   fls->namelen= 0;
  40   fls->dmend_r= dmend_rlater;
  41   fls->namelen_r= namelen_rlater;
  42 }
  43
  44 adns_status adns__findlabel_next(findlabel_state fls,
  45                                  int *lablen_r, int *labstart_r) {
  46   int lablen, jumped;
  47
  48   jumped= 0;
  49   for (;;) {
  50     fls->cbyte += 2;
  51     if (fls->cbyte > fls->dglen) goto x_truncated;
  52     if (fls->cbyte > fls->max) goto x_serverfaulty;
  53     GET_W(fls->cbyte-2,lablen);
  54     if (!(lablen & 0x0c000)) break;
  55     if ((lablen & 0x0c000) != 0x0c000) return adns_s_unknownreply;
  56     if (jumped++) {
  57       adns__diag(ads,fls->serv,fls->qu,"compressed datagram contains loop");
  58       return adns_s_serverfaulty;
  59     }
  60     if (fls->dmend_r) *(fls->dmend_r)= fls->cbyte;
  61     fls->cbyte= DNS_HDRSIZE+(lablen&0x3fff);
  62     fls->dmend_r= 0; fls->max= fls->dglen+1;
  63   }
  64   if (lablen) {
  65     if (fls->namelen) fls->namelen++;
  66     fls->namelen+= lablen;
  67     if (fls->namelen > DNS_MAXDOMAIN) return adns_s_domaintoolong;
  68     fls->cbyte+= lablen;
  69     if (fls->cbyte > fls->dglen) goto x_truncated;
  70     if (fls->cbyte > fls->max) goto x_serverfaulty;
  71   } else {
  72     if (fls->dmend_r) *(fls->dmend_r)= fls->cbyte;
  73     if (fls->namelen_r) *(fls->namelen_r)= fls->namelen;
  74   }
  75   if (labstart_r) *labstart_r= fls->cbyte;
  76   *lablen_r= lablen;
  77   return adns_s_ok;
  78
  79  x_truncated:
  80   *lablen_r= -1;
  81   return adns_s_ok;
  82
  83  x_serverfaulty:
  84   adns__diag(ads,fls->serv,fls->qu,"label in domain runs beyond end of domain");
  85   return adns_s_serverfaulty;
  86 }
  87
  88 adns_status adns__parse_domain(adns_state ads, int serv, vbuf *vb, int flags,
  89                                const byte *dgram, int dglen,
  90                                int *cbyte_io, int max) {
  91   findlabel_state fls;
  92
  93   int cbyte, lablen, labstart, namelen, i, ch;
  94   adns_status st;
  95
  96   ands__findlabel_start(&fls,ads,serv, dgram,dglen,max, *cbyte_io,cbyte_io);
  97   vb->used= 0;
  98   for (;;) {
  99     st= adns__findlabel_next(&fls,&lablen,&labstart);
 100     if (st) return st;
 101     if (lablen<0) { vb->used=0; return adns_s_ok; }
 102     if (!lablen) break;
 103     if (vb->used)
 104       if (!adns__vbuf_append(&qu->ans,".",1)) return adns_s_nolocalmem;
 105     if (flags & adns_qf_anyquote) {
 106       if (!vbuf__append_quoted1035(&qu->ans,dgram+labstart,lablen))
 107         return adns_s_nolocalmem;
 108     } else {
 109       if (!ctype_alpha(dgram[labstart])) return adns_s_invaliddomain;
 110       for (i= labstart+1; i<labstart+lablen; i++) {
 111         ch= dgram[i];
 112         if (ch != '-' && !ctype_alpha(ch) && !ctype_digit(ch))
 113           return adns_s_invaliddomain;
 114       }
 115       if (!adns__vbuf_append(&qu->ans,dgram+labstart,lablen))
 116         return adns_s_nolocalmem;
 117     }
 118   }
 119   if (!adns__vbuf_append(&qu->ans,"",1)) return adns_s_nolocalmem;
 120   return adns_s_ok;
 121 }
 122
 123 const char *adns__diag_domain(adns_state ads, int serv, adns_query qu, vbuf *vb,
 124                               int flags, const byte *dgram, int dglen, int cbyte) {
 125   adns_status st;
 126
 127   st= adns__parse_domain(ads,serv,vb,qu->flags, dgram,dglen, &cbyte,dglen);
 128   if (st == adns_s_nomemory) {
 129     return "<cannot report domain... out of memory>";
 130   }
 131   if (st) {
 132     vb->used= 0;
 133     if (!(adns__vbuf_appendstr(vb,"<bad format... ") &&
 134           adns__vbuf_appendstr(vb,adns_strerror(st)) &&
 135           adns__vbuf_appendstr(vb,">") &&
 136           adns__vbuf_append(vb,"",1))) {
 137       return "<cannot report bad format... out of memory>";
 138     }
 139   }
 140   if (!vb.used) {
 141     adns__vbuf_appendstr(vb,"<truncated ...>");
 142     adns__vbuf_append(vb,"",1);
 143   }
 144   return vb->buf;
 145 }
 146
 147 adns_status adns__findrr(adns_state ads, int serv,
 148                          const byte *dgram, int dglen, int *cbyte_io,
 149                          int *type_r, int *class_r, int *rdlen_r, int *rdstart_r,
 150                          const byte *eo_dgram, int eo_dglen, int eo_cbyte,
 151                          int *eo_matched_r) {
 152   /* Finds the extent and some of the contents of an RR in a datagram
 153    * and does some checks.  The datagram is *dgram, length dglen, and
 154    * the RR starts at *cbyte_io (which is updated afterwards to point
 155    * to the end of the RR).
 156    *
 157    * The type, class and RRdata length and start are returned iff
 158    * the corresponding pointer variables are not null.  type_r and
 159    * class_r may not be null.
 160    *
 161    * If the caller thinks they know what the owner of the RR ought to
 162    * be they can pass in details in eo_*: this is another (or perhaps
 163    * the same datagram), and a pointer to where the putative owner
 164    * starts in that datagram.  In this case *eo_matched_r will be set
 165    * to 1 if the datagram matched or 0 if it did not.  Either
 166    * both eo_dgram and eo_matched_r must both be non-null, or they
 167    * must both be null (in which case eo_dglen and eo_cbyte will be ignored).
 168    * The eo datagram and contained owner domain MUST be valid and
 169    * untruncated.
 170    *
 171    * If there is truncation then *type_r will be set to -1 and
 172    * *cbyte_io, *class_r, *rdlen_r, *rdstart_r and *eo_matched_r will be
 173    * undefined.
 174    *
 175    * If an error is returned then *type_r will be undefined too.
 176    */
 177   findlabel_state fls, eo_fls;
 178   int cbyte;
 179
 180   int tmp, rdlen, mismatch;
 181   int max, lablen, labstart, namelen, ch;
 182   int eo_max, eo_lablen, eo_labstart, eo_namelen, eo_ch;
 183   adns_status st;
 184
 185   cbyte= *cbyte_io;
 186
 187   ands__findlabel_start(&fls,ads,serv, dgram,dglen,dglen,cbyte,&cbyte);
 188   if (eo_dgram) {
 189     ands__findlabel_start(&eo_fls,ads,serv, eo_dgram,eo_dglen,eo_dglen,eo_cbyte,0);
 190     mismatch= 0;
 191   } else {
 192     mismatch= 1;
 193   }
 194
 195   for (;;) {
 196     st= adns__findlabel_next(&fls,&lablen,&labstart);
 197     if (st) return st;
 198     if (lablen<0) goto x_truncated;
 199
 200     if (!mismatch) {
 201       st= adns__findlabel_next(&eo_fls,&eo_lablen,&eo_labstart);
 202       assert(!st); assert(eo_lablen>=0);
 203       if (lablen != eo_lablen) mismatch= 1;
 204       while (!mismatch && lablen-- > 0) {
 205         ch= dgram[labstart++]; if (ctype_alpha(ch)) ch &= ~32;
 206         eo_ch= eo_dgram[eo_labstart++]; if (ctype_alpha(eo_ch)) eo_ch &= ~32;
 207         if (ch != eo_ch) mismatch= 1;
 208       }
 209     }
 210   }
 211   if (eo_matched_r) *eo_matched_r= !mismatch;
 212
 213   if (cbyte+10>dglen) goto x_truncated;
 214   GET_W(cbyte,tmp); *type_r= tmp;
 215   GET_W(cbyte,tmp); *class_r= tmp;
 216   cbyte+= 4; /* we skip the TTL */
 217   GET_W(cbyte,rdlen); if (rdlen_r) *rdlen_r= tmp;
 218   if (rdstart_r) *rdstart_r= cbyte;
 219   cbyte+= rdlen;
 220   if (cbyte>dglen) goto x_truncated;
 221   *cbyte_io= cbyte;
 222   return adns_s_ok;
 223
 224  x_truncated:
 225   *type_r= -1;
 226   return 0;;
 227 }