3 * - main handling and parsing routine for received datagrams
7 * Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
9 * It is part of adns, which is
10 * Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
11 * Copyright (C) 1999-2000 Tony Finch <dot@dotat.at>
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2, or (at your option)
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
23 * You should have received a copy of the GNU General Public License
24 * along with this program; if not, write to the Free Software Foundation,
25 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
32 void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
33 int serv, int viatcp, struct timeval now) {
34 int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here;
35 int id, f1, f2, qdcount, ancount, nscount, arcount;
36 int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
37 int rrtype, rrclass, rdlength, rdstart;
38 int anstart, nsstart, arstart;
39 int ownermatched, l, nrrs;
40 unsigned long ttl, soattl;
41 const typeinfo *typei;
46 byte *newquery, *rrsdata;
49 if (dglen<DNS_HDRSIZE) {
50 adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
61 assert(cbyte == DNS_HDRSIZE);
73 adns__diag(ads,serv,0,"server sent us a query, not a response");
77 adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
82 /* See if we can find the relevant query, or leave qu=0 otherwise ... */
85 for (qu= viatcp ? ads->tcpw.head : ads->udpw.head; qu; qu= nqu) {
87 if (qu->id != id) continue;
88 if (dglen < qu->query_dglen) continue;
89 if (memcmp(qu->query_dgram+DNS_HDRSIZE,
91 qu->query_dglen-DNS_HDRSIZE))
94 assert(qu->state == query_tcpw);
96 assert(qu->state == query_tosend);
97 if (!(qu->udpsent & (1<<serv))) continue;
102 /* We're definitely going to do something with this query now */
103 if (viatcp) LIST_UNLINK(ads->tcpw,qu);
104 else LIST_UNLINK(ads->udpw,qu);
108 /* If we're going to ignore the packet, we return as soon as we have
109 * failed the query (if any) and printed the warning message (if
116 case rcode_formaterror:
117 adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
118 if (qu) adns__query_fail(qu,adns_s_rcodeformaterror);
121 if (qu) adns__query_fail(qu,adns_s_rcodeservfail);
122 else adns__debug(ads,serv,qu,"server failure on unidentifiable query");
125 adns__warn(ads,serv,qu,"server claims not to implement our query");
126 if (qu) adns__query_fail(qu,adns_s_rcodenotimplemented);
129 adns__debug(ads,serv,qu,"server refused our query");
130 if (qu) adns__query_fail(qu,adns_s_rcoderefused);
133 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
134 if (qu) adns__query_fail(qu,adns_s_rcodeunknown);
140 adns__diag(ads,serv,0,"server sent reply without quoting our question");
141 } else if (qdcount>1) {
142 adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
144 } else if (ads->iflags & adns_if_debug) {
145 adns__vbuf_init(&tempvb);
146 adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s",
147 id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE));
148 adns__vbuf_free(&tempvb);
153 /* We're definitely going to do something with this packet and this query now. */
155 anstart= qu->query_dglen;
158 /* Now, take a look at the answer section, and see if it is complete.
159 * If it has any CNAMEs we stuff them in the answer.
163 for (rri= 0; rri<ancount; rri++) {
165 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
166 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
168 if (st) { adns__query_fail(qu,st); return; }
169 if (rrtype == -1) goto x_truncated;
171 if (rrclass != DNS_CLASS_IN) {
172 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
173 rrclass,DNS_CLASS_IN);
177 if (ads->iflags & adns_if_debug) {
178 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
179 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rrstart));
183 if (rrtype == adns_r_cname &&
184 (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
185 if (qu->flags & adns_qf_cname_forbid) {
186 adns__query_fail(qu,adns_s_prohibitedcname);
188 } else if (qu->cname_dgram) { /* Ignore second and subsequent CNAME(s) */
189 adns__debug(ads,serv,qu,"allegedly canonical name %s is actually alias for %s",
191 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart));
192 adns__query_fail(qu,adns_s_prohibitedcname);
194 } else if (wantedrrs) { /* Ignore CNAME(s) after RR(s). */
195 adns__debug(ads,serv,qu,"ignoring CNAME (to %s) coexisting with RR",
196 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart));
198 qu->cname_begin= rdstart;
199 qu->cname_dglen= dglen;
200 st= adns__parse_domain(ads,serv,qu, &qu->vb,
201 qu->flags & adns_qf_quotefail_cname
203 dgram,dglen, &rdstart,rdstart+rdlength);
204 if (!qu->vb.used) goto x_truncated;
205 if (st) { adns__query_fail(qu,st); return; }
206 l= strlen(qu->vb.buf)+1;
207 qu->answer->cname= adns__alloc_preserved(qu,l);
208 if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; }
210 qu->cname_dgram= adns__alloc_mine(qu,dglen);
211 memcpy(qu->cname_dgram,dgram,dglen);
213 memcpy(qu->answer->cname,qu->vb.buf,l);
215 adns__update_expires(qu,ttl,now);
216 /* If we find the answer section truncated after this point we restart
217 * the query at the CNAME; if beforehand then we obviously have to use
218 * TCP. If there is no truncation we can use the whole answer if
219 * it contains the relevant info.
222 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
225 adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
229 /* We defer handling truncated responses here, in case there was a CNAME
230 * which we could use.
232 if (flg_tc) goto x_truncated;
237 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
239 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
240 foundsoa= 0; soattl= 0; foundns= 0;
241 for (rri= 0; rri<nscount; rri++) {
243 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
244 &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0);
245 if (st) { adns__query_fail(qu,st); return; }
246 if (rrtype==-1) goto x_truncated;
247 if (rrclass != DNS_CLASS_IN) {
248 adns__diag(ads,serv,qu,
249 "ignoring authority RR with wrong class %d (expected IN=%d)",
250 rrclass,DNS_CLASS_IN);
253 if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; }
254 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
257 if (rcode == rcode_nxdomain) {
258 /* We still wanted to look for the SOA so we could find the TTL. */
259 adns__update_expires(qu,soattl,now);
261 if (qu->flags & adns_qf_search && !qu->cname_dgram) {
262 adns__search_next(ads,qu,now);
264 adns__query_fail(qu,adns_s_nxdomain);
269 if (foundsoa || !foundns) {
270 /* Aha ! A NODATA response, good. */
271 adns__update_expires(qu,soattl,now);
272 adns__query_fail(qu,adns_s_nodata);
276 /* Now what ? No relevant answers, no SOA, and at least some NS's.
277 * Looks like a referral. Just one last chance ... if we came across
278 * a CNAME in this datagram then we should probably do our own CNAME
279 * lookup now in the hope that we won't get a referral again.
281 if (cname_here) goto x_restartquery;
283 /* Bloody hell, I thought we asked for recursion ? */
285 adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
286 adns__query_fail(qu,adns_s_norecurse);
289 adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
291 adns__debug(ads,serv,qu,"server claims to do recursion, but gave us a referral");
292 adns__query_fail(qu,adns_s_invalidresponse);
297 /* Now, we have some RRs which we wanted. */
299 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
300 if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nomemory); return; }
304 rrsdata= qu->answer->rrs.bytes;
311 pai.nsstart= nsstart;
312 pai.nscount= nscount;
313 pai.arcount= arcount;
316 for (rri=0, nrrs=0; rri<ancount; rri++) {
317 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
318 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
320 assert(!st); assert(rrtype != -1);
321 if (rrclass != DNS_CLASS_IN ||
322 rrtype != (qu->typei->type & adns__rrt_typemask) ||
325 adns__update_expires(qu,ttl,now);
326 st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz);
327 if (st) { adns__query_fail(qu,st); return; }
328 if (rdstart==-1) goto x_truncated;
331 assert(nrrs==wantedrrs);
332 qu->answer->nrrs= nrrs;
334 /* This may have generated some child queries ... */
335 if (qu->children.head) {
336 qu->state= query_childw;
337 LIST_LINK_TAIL(ads->childw,qu);
340 adns__query_done(qu);
346 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
347 adns__query_fail(qu,adns_s_invalidresponse);
350 qu->flags |= adns_qf_usevc;
353 if (qu->cname_dgram) {
354 st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id,
355 qu->cname_dgram, qu->cname_dglen, qu->cname_begin,
356 qu->typei->type, qu->flags);
357 if (st) { adns__query_fail(qu,st); return; }
359 newquery= realloc(qu->query_dgram,qu->vb.used);
360 if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; }
362 qu->query_dgram= newquery;
363 qu->query_dglen= qu->vb.used;
364 memcpy(newquery,qu->vb.buf,qu->vb.used);
367 if (qu->state == query_tcpw) qu->state= query_tosend;
369 adns__reset_preserved(qu);
370 adns__query_send(qu,now);