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

   1 /**/
   2
   3 #include "internal.h"
   4
   5 static void cname_recurse(adns_state ads, adns_query qu, adns_queryflags xflags) {
   6   abort(); /* FIXME */
   7 }
   8
   9 void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
  10                      int serv, struct timeval now) {
  11   int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns;
  12   int id, f1, f2, qdcount, ancount, nscount, arcount, flg_ra, flg_rd, flg_tc, opcode;
  13   int rrtype, rrclass, rdlength, rdstart, ownermatched, ownerstart;
  14   int anstart, nsstart, arstart;
  15   int currentrrs;
  16   adns_query qu, nqu;
  17   dns_rcode rcode;
  18   adns_status st;
  19   vbuf vb;
  20 #error init and free vb properly
  21
  22   if (dglen<DNS_HDRSIZE) {
  23     adns__diag(ads,serv,"received datagram too short for message header (%d)",dglen);
  24     return;
  25   }
  26   GET_W(cbyte,id);
  27   GET_B(cbyte,f1);
  28   GET_B(cbyte,f2);
  29   GET_W(cbyte,qdcount);
  30   GET_W(cbyte,ancount);
  31   GET_W(cbyte,nscount);
  32   GET_W(cbyte,arcount);
  33   assert(cbyte == DNS_HDRSIZE);
  34
  35   flg_qr= f1&0x80;
  36   opcode= (f1&0x78)>>3;
  37   flg_tc= f1&0x20;
  38   flg_rd= f1&0x01;
  39   flg_ra= f2&0x80;
  40   rcode= (f1&0x0f);
  41
  42   if (flg_qr) {
  43     adns__diag(ads,serv,"server sent us a query, not a response");
  44     return;
  45   }
  46   if (opcode) {
  47     adns__diag(ads,serv,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
  48     return;
  49   }
  50   if (!qdcount) {
  51     adns__diag(ads,serv,"server sent reply without quoting our question");
  52     return;
  53   } else if (qdcount>1) {
  54     adns__diag(ads,serv,"server claimed to answer %d questions with one message",
  55                qdcount);
  56     return;
  57   }
  58   for (qu= ads->timew.head; qu; qu= nqu) {
  59     nqu= qu->next;
  60     if (qu->id != id) continue;
  61     if (dglen < qu->querylen) continue;
  62     if (memcmp(qu->querymsg+DNS_HDRSIZE,dgram+DNS_HDRSIZE,qu->querylen-DNS_HDRSIZE))
  63       continue;
  64     break;
  65   }
  66   assert(qu->cnameoff == -1);
  67   anstart= qu->querylen;
  68   if (!qu) {
  69     adns__debug(ads,serv,"reply not found (id=%02x)",id);
  70     return;
  71   }
  72
  73   LIST_UNLINK(ads->timew,qu);
  74   /* We're definitely going to do something with this query now */
  75
  76   switch (rcode) {
  77   case rcode_noerror:
  78   case rcode_nxdomain:
  79     break;
  80   case rcode_formaterror:
  81     adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
  82     adns__query_fail(ads,qu,adns_s_serverfaulty);
  83     return;
  84   case rcode_servfail:
  85     adns__query_fail(ads,qu,adns_s_servfail);
  86     return;
  87   case rcode_notimp:
  88     adns__warn(ads,serv,qu,"server claims not to implement our query");
  89     adns__query_fail(ads,qu,adns_s_notimplemented);
  90     return;
  91   case rcode_refused:
  92     adns__warn(ads,serv,qu,"server refused our query");
  93     adns__query_fail(ads,qu,adns_s_refused);
  94     return;
  95   default:
  96     adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
  97     adns__query_fail(ads,qu,adns_s_reasonunknown);
  98     return;
  99   }
 100
 101   /* Now, take a look at the answer section, and see if it is complete.
 102    * If it has any CNAMEs we stuff them in the answer.
 103    */
 104   wantedrrs= 0;
 105   for (rri= 0; rri<ancount; rri++) {
 106     rrstart= cbyte;
 107     if (qu->cname_dgram >= 0) {
 108       st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
 109                        &rrtype,&rrclass,&rdlength,&rdstart,
 110                        qu->cname_dgram,qu->cname_dglen,qu->cname_begin, &ownermatched);
 111     } else {
 112       st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
 113                        &rrtype,&rrclass,&rdlength,&rdstart,
 114                        qu->querymsg,qu->querylen,DNS_HDRSIZE, &ownermatched);
 115     }
 116     if (st) adns__query_fail(ads,qu,st);
 117     if (rrtype == -1) goto x_truncated;
 118
 119     if (rrclass != DNS_CLASS_IN) {
 120       adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
 121                  rrclass,DNS_CLASS_IN);
 122       continue;
 123     }
 124     if (!ownermatched) {
 125       if (ads->iflags & adns_if_debug) {
 126         adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
 127                     adns__diag_domain(ads,serv,&vb,qu->flags,
 128                                       dgram,dglen,rrstart,dglen));
 129       }
 130       continue;
 131     }
 132     if (rrtype == adns_r_cname &&
 133         (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
 134       if (!qu->cname_str) { /* Ignore second and subsequent CNAMEs */
 135         qu->cname_begin= rdstart;
 136         qu->cname_dgram= dgram;
 137         qu->cname_dglen= dglen;
 138         st= adns__parse_domain(ads,serv,&vb,qu->flags,
 139                                dgram,dglen, &rdstart,rdstart+rdlength);
 140         if (!vb.used) goto x_truncated;
 141         if (st) { adns__query_fail(ads,qu,st); return; }
 142         qu->cname_str= adns__vbuf_extractstring(&vb);
 143         /* If we find the answer section truncated after this point we restart
 144          * the query at the CNAME; if beforehand then we obviously have to use
 145          * TCP.  If there is no truncation we can use the whole answer if
 146          * it contains the relevant info.
 147          */
 148       } else {
 149         adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
 150                     adns__diag_domain(ads,serv,&vb,qu->flags,
 151                                       dgram,dglen, rdstart,rdstart+rdlength),
 152                     qu->cname_str);
 153       }
 154     } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
 155       wantedrrs++;
 156     } else {
 157       adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
 158     }
 159   }
 160
 161   /* If we got here then the answer section is intact. */
 162   nsstart= cbyte;
 163
 164   if (!wantedrrs) {
 165     /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
 166
 167     if (rcode == rcode_nxdomain) {
 168       adns__query_finish(ads,qu,adns_s_nxdomain);
 169       return;
 170     }
 171
 172     /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
 173     foundsoa= 0; foundns= 0;
 174     for (rri= 0; rri<nscount; rri++) {
 175       rrstart= cbyte;
 176       st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
 177                        &rrtype,&rrclass,&rdlength,&rdstart,
 178                        0,0,0,0);
 179       if (st) { adns__query_fail(ads,qu,st); return; }
 180       if (rrtype==-1) goto x_truncated;
 181       if (rrclass != DNS_CLASS_IN) {
 182         adns__diag(ads,serv,qu,
 183                    "ignoring authority RR with wrong class %d (expected IN=%d)",
 184                    rrclass,DNS_CLASS_IN);
 185         continue;
 186       }
 187       if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; }
 188       else if (rrtype == adns_r_ns_raw) { foundns= 1; }
 189     }
 190
 191     if (foundsoa || !foundns) {
 192       /* Aha !  A NODATA response, good. */
 193       adns__query_finish(ads,qu,adns_s_nodata);
 194       return;
 195     }
 196
 197     /* Now what ?  No relevant answers, no SOA, and at least some NS's.
 198      * Looks like a referral.  Just one last chance ... if we came across
 199      * a CNAME in this datagram then we should probably do our own CNAME
 200      * lookup now in the hope that we won't get a referral again.
 201      */
 202     if (qu->cname_dgram == dgram) { cname_recurse(ads,qu,0); return; }
 203
 204     /* Bloody hell, I thought we asked for recursion ? */
 205     if (flg_rd) {
 206       adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
 207     }
 208     if (!flg_ra) {
 209       adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
 210       adns__query_fail(ads,qu,adns_s_norecurse);
 211     } else {
 212       adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
 213       adns__query_fail(ads,qu,adns_s_serverfaulty);
 214     }
 215     return;
 216   }
 217
 218   /* Now, we have some RRs which we wanted. */
 219
 220   if (!adns__vbuf_ensure(&qu->ansbuf,qu->typei->rrsz*wantedrrs)) {
 221     adns__query_fail(ads,qu,adns_s_nolocalmem);
 222     return;
 223   }
 224
 225   cbyte= anstart;
 226   currentrrs= 0;
 227   arstart= -1;
 228   qu->ansbuf.used= 0;
 229   for (rri=0; rri<ancount; rri++) {
 230     if (qu->cname_dgram >= 0) {
 231       st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
 232                        &rrtype,&rrclass,&rdlength,&rdstart,
 233                        qu->cname_dgram,qu->cname_dglen,qu->cname_begin, &ownermatched);
 234     } else {
 235       st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
 236                        &rrtype,&rrclass,&rdlength,&rdstart,
 237                        qu->querymsg,qu->querylen,DNS_HDRSIZE, &ownermatched);
 238     }
 239     assert(!st); assert(rrtype != -1);
 240     if (rrclass != DNS_CLASS_IN ||
 241         rrtype != (qu->typei->type & adns__rrt_typemask) ||
 242         !ownermatched)
 243       continue;
 244     assert(currentrrs<wantedrrs);
 245     qu->ansbuf.used += quj->typei->rrsz;
 246     st= qu->typei->parse(ads,qu,serv,&vb,
 247                          dgram,dglen, &rdstart,rdstart+rdlength,
 248                          (void*)(qu->ansbuf.buf+qu->ansbuf.used));
 249     if (st) { adns__query_fail(ads,qu,st); return; }
 250     if (rdstart==-1) goto x_truncated;
 251   }
 252
 253   /* This may have generated some child queries ... */
 254   if (qu->children.head) {
 255     qu->state= query_child;
 256     LIST_LINK_TAIL(ads->childw,qu);
 257     return;
 258   }
 259
 260   adns__query_finish(ads,qu,adns_s_ok);
 261   return;
 262
 263 x_truncated:
 264   if (!flg_tc) {
 265     adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
 266     adns__query_fail(ads,qu,adns_s_serverfaulty);
 267     return;
 268   }
 269   if (qu->cname_dgram) { cname_recurse(ads,qu,adns_qf_usevc); return; }
 270   ans= (adns_answer*)qu->ans.buf;
 271   ans->nrrs= 0;
 272   qu->ans.used= sizeof(adns_answer);
 273   qu->flags |= adns_qf_usevc;
 274   adns__query_udp(ads,qu,now);
 275 }