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