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

   1 /*
   2  * reply.c
   3  * - main handling and parsing routine for received datagrams
   4  */
   5 /*
   6  *  This file is part of adns, which is Copyright (C) 1997, 1998 Ian Jackson
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 2, or (at your option)
  11  *  any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to the Free Software Foundation,
  20  *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  21  */
  22
  23 #include "internal.h"
  24
  25 static void cname_recurse(adns_state ads, adns_query qu, adns_queryflags xflags) {
  26   abort(); /* FIXME */
  27 }
  28
  29 void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
  30                      int serv, struct timeval now) {
  31   int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns;
  32   int id, f1, f2, qdcount, ancount, nscount, arcount, flg_ra, flg_rd, flg_tc, opcode;
  33   int rrtype, rrclass, rdlength, rdstart, ownermatched, ownerstart;
  34   int anstart, nsstart, arstart;
  35   int currentrrs;
  36   adns_query qu, nqu;
  37   dns_rcode rcode;
  38   adns_status st;
  39
  40   if (dglen<DNS_HDRSIZE) {
  41     adns__diag(ads,serv,"received datagram too short for message header (%d)",dglen);
  42     return;
  43   }
  44   GET_W(cbyte,id);
  45   GET_B(cbyte,f1);
  46   GET_B(cbyte,f2);
  47   GET_W(cbyte,qdcount);
  48   GET_W(cbyte,ancount);
  49   GET_W(cbyte,nscount);
  50   GET_W(cbyte,arcount);
  51   assert(cbyte == DNS_HDRSIZE);
  52
  53   flg_qr= f1&0x80;
  54   opcode= (f1&0x78)>>3;
  55   flg_tc= f1&0x20;
  56   flg_rd= f1&0x01;
  57   flg_ra= f2&0x80;
  58   rcode= (f1&0x0f);
  59
  60   if (flg_qr) {
  61     adns__diag(ads,serv,"server sent us a query, not a response");
  62     return;
  63   }
  64   if (opcode) {
  65     adns__diag(ads,serv,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
  66     return;
  67   }
  68   if (!qdcount) {
  69     adns__diag(ads,serv,"server sent reply without quoting our question");
  70     return;
  71   } else if (qdcount>1) {
  72     adns__diag(ads,serv,"server claimed to answer %d questions with one message",
  73                qdcount);
  74     return;
  75   }
  76   for (qu= ads->timew.head; qu; qu= nqu) {
  77     nqu= qu->next;
  78     if (qu->id != id) continue;
  79     if (dglen < qu->querylen) continue;
  80     if (memcmp(qu->querymsg+DNS_HDRSIZE,dgram+DNS_HDRSIZE,qu->querylen-DNS_HDRSIZE))
  81       continue;
  82     break;
  83   }
  84   assert(qu->cnameoff == -1);
  85   anstart= qu->querylen;
  86   if (!qu) {
  87     adns__debug(ads,serv,"reply not found (id=%02x)",id);
  88     return;
  89   }
  90
  91   LIST_UNLINK(ads->timew,qu);
  92   /* We're definitely going to do something with this query now */
  93
  94   switch (rcode) {
  95   case rcode_noerror:
  96   case rcode_nxdomain:
  97     break;
  98   case rcode_formaterror:
  99     adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
 100     adns__query_fail(ads,qu,adns_s_serverfaulty);
 101     return;
 102   case rcode_servfail:
 103     adns__query_fail(ads,qu,adns_s_servfail);
 104     return;
 105   case rcode_notimp:
 106     adns__warn(ads,serv,qu,"server claims not to implement our query");
 107     adns__query_fail(ads,qu,adns_s_notimplemented);
 108     return;
 109   case rcode_refused:
 110     adns__warn(ads,serv,qu,"server refused our query");
 111     adns__query_fail(ads,qu,adns_s_refused);
 112     return;
 113   default:
 114     adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
 115     adns__query_fail(ads,qu,adns_s_reasonunknown);
 116     return;
 117   }
 118
 119   /* Now, take a look at the answer section, and see if it is complete.
 120    * If it has any CNAMEs we stuff them in the answer.
 121    */
 122   wantedrrs= 0;
 123   for (rri= 0; rri<ancount; rri++) {
 124     rrstart= cbyte;
 125     if (qu->cname_dgram >= 0) {
 126       st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
 127                        &rrtype,&rrclass,&rdlength,&rdstart,
 128                        qu->cname_dgram,qu->cname_dglen,qu->cname_begin, &ownermatched);
 129     } else {
 130       st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
 131                        &rrtype,&rrclass,&rdlength,&rdstart,
 132                        qu->querymsg,qu->querylen,DNS_HDRSIZE, &ownermatched);
 133     }
 134     if (st) adns__query_fail(ads,qu,st);
 135     if (rrtype == -1) goto x_truncated;
 136
 137     if (rrclass != DNS_CLASS_IN) {
 138       adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
 139                  rrclass,DNS_CLASS_IN);
 140       continue;
 141     }
 142     if (!ownermatched) {
 143       if (ads->iflags & adns_if_debug) {
 144         adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
 145                     adns__diag_domain(ads,serv,&qu->vb,qu->flags,
 146                                       dgram,dglen,rrstart,dglen));
 147       }
 148       continue;
 149     }
 150     if (rrtype == adns_r_cname &&
 151         (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
 152       if (!qu->cname_str) { /* Ignore second and subsequent CNAMEs */
 153         qu->cname_begin= rdstart;
 154         qu->cname_dgram= dgram;
 155         qu->cname_dglen= dglen;
 156         st= adns__parse_domain(ads,serv,&qu->vb,qu->flags,
 157                                dgram,dglen, &rdstart,rdstart+rdlength);
 158         if (!vb.used) goto x_truncated;
 159         if (st) { adns__query_fail(ads,qu,st); return; }
 160         qu->answer->cname= adns__savestring(qu);
 161         if (!qu->answer->cname) return;
 162         /* If we find the answer section truncated after this point we restart
 163          * the query at the CNAME; if beforehand then we obviously have to use
 164          * TCP.  If there is no truncation we can use the whole answer if
 165          * it contains the relevant info.
 166          */
 167       } else {
 168         adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
 169                     adns__diag_domain(ads,serv,&qu->vb,qu->flags,
 170                                       dgram,dglen, rdstart,rdstart+rdlength),
 171                     qu->cname_str);
 172       }
 173     } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
 174       wantedrrs++;
 175     } else {
 176       adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
 177     }
 178   }
 179
 180   /* If we got here then the answer section is intact. */
 181   nsstart= cbyte;
 182
 183   if (!wantedrrs) {
 184     /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
 185
 186     if (rcode == rcode_nxdomain) {
 187       adns__query_finish(ads,qu,adns_s_nxdomain);
 188       return;
 189     }
 190
 191     /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
 192     foundsoa= 0; foundns= 0;
 193     for (rri= 0; rri<nscount; rri++) {
 194       rrstart= cbyte;
 195       st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
 196                        &rrtype,&rrclass,&rdlength,&rdstart,
 197                        0,0,0,0);
 198       if (st) { adns__query_fail(ads,qu,st); return; }
 199       if (rrtype==-1) goto x_truncated;
 200       if (rrclass != DNS_CLASS_IN) {
 201         adns__diag(ads,serv,qu,
 202                    "ignoring authority RR with wrong class %d (expected IN=%d)",
 203                    rrclass,DNS_CLASS_IN);
 204         continue;
 205       }
 206       if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; }
 207       else if (rrtype == adns_r_ns_raw) { foundns= 1; }
 208     }
 209
 210     if (foundsoa || !foundns) {
 211       /* Aha !  A NODATA response, good. */
 212       adns__query_finish(ads,qu,adns_s_nodata);
 213       return;
 214     }
 215
 216     /* Now what ?  No relevant answers, no SOA, and at least some NS's.
 217      * Looks like a referral.  Just one last chance ... if we came across
 218      * a CNAME in this datagram then we should probably do our own CNAME
 219      * lookup now in the hope that we won't get a referral again.
 220      */
 221     if (qu->cname_dgram == dgram) { cname_recurse(ads,qu,0); return; }
 222
 223     /* Bloody hell, I thought we asked for recursion ? */
 224     if (flg_rd) {
 225       adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
 226     }
 227     if (!flg_ra) {
 228       adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
 229       adns__query_fail(ads,qu,adns_s_norecurse);
 230     } else {
 231       adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
 232       adns__query_fail(ads,qu,adns_s_serverfaulty);
 233     }
 234     return;
 235   }
 236
 237   /* Now, we have some RRs which we wanted. */
 238
 239   qu->ans->rrs= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
 240   if (!qu->ans->rrs) return;
 241
 242   cbyte= anstart;
 243   arstart= -1;
 244   for (rri=0; rri<ancount; rri++) {
 245     if (qu->cname_dgram >= 0) {
 246       st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
 247                        &rrtype,&rrclass,&rdlength,&rdstart,
 248                        qu->cname_dgram,qu->cname_dglen,qu->cname_begin, &ownermatched);
 249     } else {
 250       st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
 251                        &rrtype,&rrclass,&rdlength,&rdstart,
 252                        qu->querymsg,qu->querylen,DNS_HDRSIZE, &ownermatched);
 253     }
 254     assert(!st); assert(rrtype != -1);
 255     if (rrclass != DNS_CLASS_IN ||
 256         rrtype != (qu->typei->type & adns__rrt_typemask) ||
 257         !ownermatched)
 258       continue;
 259     assert(qu->ans->nrrs<wantedrrs);
 260     st= qu->typei->parse(ads,qu,serv,
 261                          dgram,dglen, &rdstart,rdstart+rdlength,
 262                          qu->ans->rrs.bytes+qu->ans->nrrs*quj->typei->rrsz);
 263     if (st) { adns__query_fail(ads,qu,st); return; }
 264     if (rdstart==-1) goto x_truncated;
 265   }
 266
 267   /* This may have generated some child queries ... */
 268   if (qu->children.head) {
 269     qu->state= query_child;
 270     LIST_LINK_TAIL(ads->childw,qu);
 271     return;
 272   }
 273
 274   adns__query_finish(ads,qu,adns_s_ok);
 275   return;
 276
 277  x_truncated:
 278   if (!flg_tc) {
 279     adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
 280     adns__query_fail(ads,qu,adns_s_serverfaulty);
 281     return;
 282   }
 283   if (qu->cname_dgram) { cname_recurse(ads,qu,adns_qf_usevc); return; }
 284   adns__reset_cnameonly(ads,qu);
 285   qu->flags |= adns_qf_usevc;
 286   adns__query_udp(ads,qu,now);
 287 }