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"
51 " too short for message header (%d)",dglen);
62 assert(cbyte == DNS_HDRSIZE);
74 adns__diag(ads,serv,0,"server sent us a query, not a response");
78 adns__diag(ads,serv,0,"server sent us unknown opcode"
79 " %d (wanted 0=QUERY)",opcode);
84 /* See if we can find the relevant query, or leave qu=0 otherwise ... */
87 for (qu= viatcp ? ads->tcpw.head : ads->udpw.head; qu; qu= nqu) {
89 if (qu->id != id) continue;
90 if (dglen < qu->query_dglen) continue;
91 if (memcmp(qu->query_dgram+DNS_HDRSIZE,
93 qu->query_dglen-DNS_HDRSIZE))
96 assert(qu->state == query_tcpw);
98 assert(qu->state == query_tosend);
99 if (!(qu->udpsent & (1<<serv))) continue;
104 /* We're definitely going to do something with this query now */
105 if (viatcp) LIST_UNLINK(ads->tcpw,qu);
106 else LIST_UNLINK(ads->udpw,qu);
110 /* If we're going to ignore the packet, we return as soon as we have
111 * failed the query (if any) and printed the warning message (if
118 case rcode_formaterror:
119 adns__warn(ads,serv,qu,"server cannot understand our query"
121 if (qu) adns__query_fail(qu,adns_s_rcodeformaterror);
124 if (qu) adns__query_fail(qu,adns_s_rcodeservfail);
125 else adns__debug(ads,serv,qu,"server failure on unidentifiable query");
128 adns__warn(ads,serv,qu,"server claims not to implement our query");
129 if (qu) adns__query_fail(qu,adns_s_rcodenotimplemented);
132 adns__debug(ads,serv,qu,"server refused our query");
133 if (qu) adns__query_fail(qu,adns_s_rcoderefused);
136 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
137 if (qu) adns__query_fail(qu,adns_s_rcodeunknown);
143 adns__diag(ads,serv,0,"server sent reply without quoting our question");
144 } else if (qdcount>1) {
145 adns__diag(ads,serv,0,"server claimed to answer %d"
146 " questions with one message", qdcount);
147 } else if (ads->iflags & adns_if_debug) {
148 adns__vbuf_init(&tempvb);
149 adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s",
150 id, adns__diag_domain(ads,serv,0,&tempvb,
151 dgram,dglen,DNS_HDRSIZE));
152 adns__vbuf_free(&tempvb);
157 /* We're definitely going to do something with this packet and this
160 anstart= qu->query_dglen;
163 /* Now, take a look at the answer section, and see if it is complete.
164 * If it has any CNAMEs we stuff them in the answer.
168 for (rri= 0; rri<ancount; rri++) {
170 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
171 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
173 if (st) { adns__query_fail(qu,st); return; }
174 if (rrtype == -1) goto x_truncated;
176 if (rrclass != DNS_CLASS_IN) {
177 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d"
178 " (expected IN=%d)", rrclass,DNS_CLASS_IN);
182 if (ads->iflags & adns_if_debug) {
183 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
184 adns__diag_domain(ads,serv,qu, &qu->vb,
185 dgram,dglen,rrstart));
189 if (rrtype == adns_r_cname &&
190 (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
191 if (qu->flags & adns_qf_cname_forbid) {
192 adns__query_fail(qu,adns_s_prohibitedcname);
194 } else if (qu->cname_dgram) { /* Ignore second and subsequent CNAME(s) */
195 adns__debug(ads,serv,qu,"allegedly canonical name %s"
196 " is actually alias for %s", qu->answer->cname,
197 adns__diag_domain(ads,serv,qu, &qu->vb,
198 dgram,dglen,rdstart));
199 adns__query_fail(qu,adns_s_prohibitedcname);
201 } else if (wantedrrs) { /* Ignore CNAME(s) after RR(s). */
202 adns__debug(ads,serv,qu,"ignoring CNAME (to %s) coexisting with RR",
203 adns__diag_domain(ads,serv,qu, &qu->vb,
204 dgram,dglen,rdstart));
206 qu->cname_begin= rdstart;
207 qu->cname_dglen= dglen;
208 st= adns__parse_domain(ads,serv,qu, &qu->vb,
209 qu->flags & adns_qf_quotefail_cname
211 dgram,dglen, &rdstart,rdstart+rdlength);
212 if (!qu->vb.used) goto x_truncated;
213 if (st) { adns__query_fail(qu,st); return; }
214 l= strlen(qu->vb.buf)+1;
215 qu->answer->cname= adns__alloc_preserved(qu,l);
216 if (!qu->answer->cname) {
217 adns__query_fail(qu,adns_s_nomemory);
221 qu->cname_dgram= adns__alloc_mine(qu,dglen);
222 memcpy(qu->cname_dgram,dgram,dglen);
224 memcpy(qu->answer->cname,qu->vb.buf,l);
226 adns__update_expires(qu,ttl,now);
227 /* If we find the answer section truncated after this point we restart
228 * the query at the CNAME; if beforehand then we obviously have to use
229 * TCP. If there is no truncation we can use the whole answer if
230 * it contains the relevant info.
233 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
236 adns__debug(ads,serv,qu,"ignoring answer RR"
237 " with irrelevant type %d",rrtype);
241 /* We defer handling truncated responses here, in case there was a CNAME
242 * which we could use.
244 if (flg_tc) goto x_truncated;
249 /* Oops, NODATA or NXDOMAIN or perhaps a referral
250 * (which would be a problem) */
252 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records
253 * in authority section */
254 foundsoa= 0; soattl= 0; foundns= 0;
255 for (rri= 0; rri<nscount; rri++) {
257 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
258 &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0);
259 if (st) { adns__query_fail(qu,st); return; }
260 if (rrtype==-1) goto x_truncated;
261 if (rrclass != DNS_CLASS_IN) {
262 adns__diag(ads,serv,qu,
263 "ignoring authority RR with wrong class %d"
264 " (expected IN=%d)", rrclass,DNS_CLASS_IN);
267 if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; }
268 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
271 if (rcode == rcode_nxdomain) {
272 /* We still wanted to look for the SOA so we could find the TTL. */
273 adns__update_expires(qu,soattl,now);
275 if (qu->flags & adns_qf_search && !qu->cname_dgram) {
276 adns__search_next(ads,qu,now);
278 adns__query_fail(qu,adns_s_nxdomain);
283 if (foundsoa || !foundns) {
284 /* Aha ! A NODATA response, good. */
285 adns__update_expires(qu,soattl,now);
286 adns__query_fail(qu,adns_s_nodata);
290 /* Now what ? No relevant answers, no SOA, and at least some NS's.
291 * Looks like a referral. Just one last chance ... if we came across
292 * a CNAME in this datagram then we should probably do our own CNAME
293 * lookup now in the hope that we won't get a referral again.
295 if (cname_here) goto x_restartquery;
297 /* Bloody hell, I thought we asked for recursion ? */
299 adns__diag(ads,serv,qu,"server is not willing"
300 " to do recursive lookups for us");
301 adns__query_fail(qu,adns_s_norecurse);
304 adns__diag(ads,serv,qu,"server thinks"
305 " we didn't ask for recursive lookup");
307 adns__debug(ads,serv,qu,"server claims to do recursion,"
308 " but gave us a referral");
309 adns__query_fail(qu,adns_s_invalidresponse);
314 /* Now, we have some RRs which we wanted. */
316 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
317 if (!qu->answer->rrs.untyped) {
318 adns__query_fail(qu,adns_s_nomemory);
324 rrsdata= qu->answer->rrs.bytes;
331 pai.nsstart= nsstart;
332 pai.nscount= nscount;
333 pai.arcount= arcount;
336 for (rri=0, nrrs=0; rri<ancount; rri++) {
337 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
338 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
340 assert(!st); assert(rrtype != -1);
341 if (rrclass != DNS_CLASS_IN ||
342 rrtype != (qu->typei->type & adns__rrt_typemask) ||
345 adns__update_expires(qu,ttl,now);
346 st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz);
347 if (st) { adns__query_fail(qu,st); return; }
348 if (rdstart==-1) goto x_truncated;
351 assert(nrrs==wantedrrs);
352 qu->answer->nrrs= nrrs;
354 /* This may have generated some child queries ... */
355 if (qu->children.head) {
356 qu->state= query_childw;
357 LIST_LINK_TAIL(ads->childw,qu);
360 adns__query_done(qu);
366 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
367 adns__query_fail(qu,adns_s_invalidresponse);
370 qu->flags |= adns_qf_usevc;
373 if (qu->cname_dgram) {
374 st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id,
375 qu->cname_dgram,qu->cname_dglen,qu->cname_begin,
376 qu->typei->type, qu->flags);
377 if (st) { adns__query_fail(qu,st); return; }
379 newquery= realloc(qu->query_dgram,qu->vb.used);
380 if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; }
382 qu->query_dgram= newquery;
383 qu->query_dglen= qu->vb.used;
384 memcpy(newquery,qu->vb.buf,qu->vb.used);
387 if (qu->state == query_tcpw) qu->state= query_tosend;
389 adns__reset_preserved(qu);
390 adns__query_send(qu,now);