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_tc;
  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   adns_answer *ans;
  20
  21   cbyte= 0;
  22
  23   if (dglen<DNS_HDRSIZE) {
  24     adns__diag(ads,serv,"received datagram too short for message header (%d)",dglen);
  25     return;
  26   }
  27   GET_W(cbyte,id);
  28   GET_B(cbyte,f1);
  29   GET_B(cbyte,f2);
  30   GET_W(cbyte,qdcount);
  31   GET_W(cbyte,ancount);
  32   GET_W(cbyte,nscount);
  33   GET_W(cbyte,arcount);
  34   assert(cbyte == DNS_HDRSIZE);
  35
  36   flg_tc= f1&0x20;
  37   flg_ra= f2&0x80;
  38
  39   if (f1&0x80) {
  40     adns__diag(ads,serv,"server sent us a query, not a response");
  41     return;
  42   }
  43   if (f1&0x70) {
  44     adns__diag(ads,serv,"server sent us unknown opcode %d (wanted 0=QUERY)",
  45                (f1>>4)&0x70);
  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   if (!(f1&0x01)) {
  75     adns__diag(ads,serv,"server thinks we didn't ask for recursive lookup");
  76     adns__query_fail(ads,qu,adns_s_serverfaulty);
  77     return;
  78   }
  79
  80   rcode= (f1&0x0f);
  81   switch (rcode) {
  82   case rcode_noerror:
  83   case rcode_nxdomain:
  84     break;
  85   case rcode_formaterror:
  86     adns__warn(ads,serv,"server cannot understand our query (Format Error)");
  87     adns__query_fail(ads,qu,adns_s_serverfaulty);
  88     return;
  89   case rcode_servfail:
  90     adns__query_fail(ads,qu,adns_s_servfail);
  91     return;
  92   case rcode_notimp:
  93     adns__warn(ads,serv,"server claims not to implement our query");
  94     adns__query_fail(ads,qu,adns_s_notimplemented);
  95     return;
  96   case rcode_refused:
  97     adns__warn(ads,serv,"server refused our query");
  98     adns__query_fail(ads,qu,adns_s_refused);
  99     return;
 100   default:
 101     adns__warn(ads,serv,"server gave unknown response code %d",rcode);
 102     adns__query_fail(ads,qu,adns_s_reasonunknown);
 103     return;
 104   }
 105
 106   /* Now, take a look at the answer section, and see if it is complete.
 107    * If it has any CNAMEs we stuff them in the answer.
 108    */
 109   wantedrrs= 0;
 110   for (rri= 0; rri<ancount; rri++) {
 111     rrstart= cbyte;
 112     if (qu->cnameoff >= 0) {
 113       st= adns__get_rr_temp(ads,qu,serv, dgram,dglen,&cbyte,
 114                             &rrtype,&rrclass,&rdlength,&rdstart,
 115                             dgram,dglen,qu->cnameoff, &ownermatched);
 116     } else {
 117       st= adns__get_rr_temp(ads,qu,serv, dgram,dglen,&cbyte,
 118                             &rrtype,&rrclass,&rdlength,&rdstart,
 119                             qu->querymsg,qu->querylen,DNS_HDRSIZE, &ownermatched);
 120     }
 121     if (st) adns__query_fail(ads,qu,st);
 122     if (rrtype == -1) goto x_truncated;
 123
 124     if (rrclass != DNS_CLASS_IN) {
 125       adns__diag(ads,serv,"ignoring answer RR with wrong class %d (expected IN=%d)",
 126                  rrclass,DNS_CLASS_IN);
 127       continue;
 128     }
 129     if (!ownermatched) {
 130       if (ads->iflags & adns_if_debug) {
 131         st= adns__get_domain_temp(ads,qu,serv, dgram,dglen,&rrstart,dglen, &ownerstart);
 132         if (st)
 133           adns__debug(ads,serv, "ignoring RR with an irrelevant owner"
 134                       " whose format is bad, code %d",st);
 135         else if (ownerstart>=0)
 136           adns__debug(ads,serv, "ignoring RR with an irrelevant owner"
 137                       " \"%s\"", qu->ans.buf+ownerstart);
 138         else
 139           adns__debug(ads,serv,"ignoring RR with an irrelevant truncated owner");
 140       }
 141       continue;
 142     }
 143     if (qu->cnameoff<0 &&
 144         (qu->typei->type & adns__rrt_typemask) != adns_r_cname &&
 145         rrtype == adns_r_cname) { /* Ignore second and subsequent CNAMEs */
 146       st= adns__get_domain_perm(ads,qu,serv, dgram,dglen,
 147                                 &rdstart,rdstart+rdlength,&qu->cnameoff);
 148       if (st) { adns__query_fail(ads,qu,st); return; }
 149       if (qu->cnameoff==-1) goto x_truncated;
 150       /* If we find the answer section truncated after this point we restart
 151        * the query at the CNAME; if beforehand then we obviously have to use
 152        * TCP.  If there is no truncation we can use the whole answer if
 153        * it contains the relevant info.
 154        */
 155     } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
 156       wantedrrs++;
 157     } else {
 158       adns__debug(ads,serv,"ignoring answer RR with irrelevant type %d",rrtype);
 159     }
 160   }
 161
 162   /* If we got here then the answer section is intact. */
 163   nsstart= cbyte;
 164
 165   if (!wantedrrs) {
 166     /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
 167
 168     if (rcode == rcode_nxdomain) {
 169       adns__query_finish(ads,qu,adns_s_nxdomain);
 170       return;
 171     }
 172
 173     /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
 174     foundsoa= 0; foundns= 0;
 175     for (rri= 0; rri<nscount; rri++) {
 176       rrstart= cbyte;
 177       st= adns__get_rr_temp(ads,qu,serv, dgram,dglen,&cbyte,
 178                             &rrtype,&rrclass, &rdlength,&rdstart, 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,"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 then perhaps we should do our own CNAME lookup.
 199      */
 200     if (qu->cnameoff != -1) { cname_recurse(ads,qu,0); return; }
 201
 202     /* Bloody hell, I thought we asked for recursion ? */
 203     if (!flg_ra) {
 204       adns__diag(ads,serv,"server is not willing to do recursive lookups for us");
 205       adns__query_fail(ads,qu,adns_s_norecurse);
 206       return;
 207     }
 208     adns__diag(ads,serv,"server claims to do recursion, but gave us a referral");
 209     adns__query_fail(ads,qu,adns_s_serverfaulty);
 210     return;
 211   }
 212
 213   /* Now, we have some RRs which we wanted. */
 214
 215   qu->rrsoff= adns__vbuf_malloc(&qu->ans,qu->typei->rrsz*wantedrrs);
 216   if (qu->rrsoff == -1) adns__query_fail(ads,qu,adns_s_nolocalmem);
 217
 218   cbyte= anstart;
 219   currentrrs= 0;
 220   arstart= -1;
 221   for (rri=0; rri<ancount; rri++) {
 222     st= adns__get_rr_temp(ads,qu,serv, dgram,dglen,&cbyte,
 223                           &rrtype,&rrclass, &rdlength,&rdstart, 0,0,0,0);
 224     assert(!st); assert(rrtype != -1);
 225     if (rrclass != DNS_CLASS_IN ||
 226         rrtype != (qu->typei->type & adns__rrt_typemask))
 227       continue;
 228     assert(currentrrs<wantedrrs);
 229     st= qu->typei->get_fn(ads,qu,serv, dgram,dglen, &rdstart,rdstart+rdlength,
 230                           nsstart,arcount,&arstart, qu->rrsoff,&currentrrs);
 231     if (st) { adns__query_fail(ads,qu,st); return; }
 232     if (currentrrs==-1) goto x_truncated;
 233   }
 234
 235   /* This may have generated some child queries ... */
 236   if (qu->children.head) {
 237     qu->state= query_child;
 238     LIST_LINK_TAIL(ads->childw,qu);
 239     return;
 240   }
 241
 242   adns__query_finish(ads,qu,adns_s_ok);
 243   return;
 244
 245 x_truncated:
 246   if (!flg_tc) {
 247     adns__diag(ads,serv,"server sent datagram which points outside itself");
 248     adns__query_fail(ads,qu,adns_s_serverfaulty);
 249     return;
 250   }
 251   if (qu->cnameoff != -1) { cname_recurse(ads,qu,adns_qf_usevc); return; }
 252   qu->cnameoff= -1;
 253   qu->rrsoff= -1;
 254   ans= (adns_answer*)qu->ans.buf;
 255   ans->nrrs= 0;
 256   qu->ans.used= sizeof(adns_answer);
 257   qu->flags |= adns_qf_usevc;
 258   adns__query_udp(ads,qu,now);
 259 }