3 * - main handling and parsing routine for received datagrams
6 * This file is part of adns, which is
7 * Copyright (C) 1997-2000,2003,2006,2014-2016 Ian Jackson
8 * Copyright (C) 2014 Mark Wooding
9 * Copyright (C) 1999-2000,2003,2006 Tony Finch
10 * Copyright (C) 1991 Massachusetts Institute of Technology
11 * (See the file INSTALL for full details.)
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 3, 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.
31 void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
32 int serv, int viatcp, struct timeval now) {
33 int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here;
34 int id, f1, f2, qdcount, ancount, nscount, arcount;
35 int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
36 int rrtype, rrclass, rdlength, rdstart;
38 int ownermatched, l, nrrs;
39 unsigned long ttl, soattl;
40 const typeinfo *typei;
45 byte *newquery, *rrsdata;
48 if (dglen<DNS_HDRSIZE) {
49 adns__diag(ads,serv,0,"received datagram"
50 " 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"
78 " %d (wanted 0=QUERY)",opcode);
83 /* See if we can find the relevant query, or leave qu=0 otherwise ... */
86 for (qu= viatcp ? ads->tcpw.head : ads->udpw.head; qu; qu= nqu) {
88 if (qu->id != id) continue;
89 if (dglen < qu->query_dglen) continue;
90 if (memcmp(qu->query_dgram+DNS_HDRSIZE,
92 qu->query_dglen-DNS_HDRSIZE))
95 assert(qu->state == query_tcpw);
97 assert(qu->state == query_tosend);
98 if (!(qu->udpsent & (1<<serv))) continue;
103 /* We're definitely going to do something with this query now */
104 if (viatcp) LIST_UNLINK(ads->tcpw,qu);
105 else LIST_UNLINK(ads->udpw,qu);
109 /* If we're going to ignore the packet, we return as soon as we have
110 * failed the query (if any) and printed the warning message (if
117 case rcode_formaterror:
118 adns__warn(ads,serv,qu,"server cannot understand our query"
120 if (qu) adns__query_fail(qu,adns_s_rcodeformaterror);
123 if (qu) adns__query_fail(qu,adns_s_rcodeservfail);
124 else adns__debug(ads,serv,qu,"server failure on unidentifiable query");
127 adns__warn(ads,serv,qu,"server claims not to implement our query");
128 if (qu) adns__query_fail(qu,adns_s_rcodenotimplemented);
131 adns__debug(ads,serv,qu,"server refused our query");
132 if (qu) adns__query_fail(qu,adns_s_rcoderefused);
135 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
136 if (qu) adns__query_fail(qu,adns_s_rcodeunknown);
142 adns__diag(ads,serv,0,"server sent reply without quoting our question");
143 } else if (qdcount>1) {
144 adns__diag(ads,serv,0,"server claimed to answer %d"
145 " questions with one message", qdcount);
146 } else if (ads->iflags & adns_if_debug) {
147 adns__vbuf_init(&tempvb);
148 adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s",
149 id, adns__diag_domain(ads,serv,0,&tempvb,
150 dgram,dglen,DNS_HDRSIZE));
151 adns__vbuf_free(&tempvb);
156 /* We're definitely going to do something with this packet and this
159 anstart= qu->query_dglen;
161 /* Now, take a look at the answer section, and see if it is complete.
162 * If it has any CNAMEs we stuff them in the answer.
166 for (rri= 0; rri<ancount; rri++) {
168 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
169 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
171 if (st) { adns__query_fail(qu,st); return; }
172 if (rrtype == -1) goto x_truncated;
174 if (rrclass != DNS_CLASS_IN) {
175 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d"
176 " (expected IN=%d)", rrclass,DNS_CLASS_IN);
180 if (ads->iflags & adns_if_debug) {
181 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
182 adns__diag_domain(ads,serv,qu, &qu->vb,
183 dgram,dglen,rrstart));
187 if (rrtype == adns_r_cname &&
188 (qu->answer->type & adns_rrt_typemask) != adns_r_cname) {
189 if (qu->flags & adns_qf_cname_forbid) {
190 adns__query_fail(qu,adns_s_prohibitedcname);
192 } else if (qu->cname_dgram) { /* Ignore second and subsequent CNAME(s) */
193 adns__debug(ads,serv,qu,"allegedly canonical name %s"
194 " is actually alias for %s", qu->answer->cname,
195 adns__diag_domain(ads,serv,qu, &qu->vb,
196 dgram,dglen,rdstart));
197 adns__query_fail(qu,adns_s_prohibitedcname);
199 } else if (wantedrrs) { /* Ignore CNAME(s) after RR(s). */
200 adns__debug(ads,serv,qu,"ignoring CNAME (to %s) coexisting with RR",
201 adns__diag_domain(ads,serv,qu, &qu->vb,
202 dgram,dglen,rdstart));
204 qu->cname_begin= rdstart;
205 qu->cname_dglen= dglen;
206 st= adns__parse_domain(ads,serv,qu, &qu->vb,
207 qu->flags & adns_qf_quotefail_cname
209 dgram,dglen, &rdstart,rdstart+rdlength);
210 if (!qu->vb.used) goto x_truncated;
211 if (st) { adns__query_fail(qu,st); return; }
212 l= strlen(qu->vb.buf)+1;
213 qu->answer->cname= adns__alloc_preserved(qu,l);
214 if (!qu->answer->cname) {
215 adns__query_fail(qu,adns_s_nomemory);
219 qu->cname_dgram= adns__alloc_mine(qu,dglen);
220 memcpy(qu->cname_dgram,dgram,dglen);
222 memcpy(qu->answer->cname,qu->vb.buf,l);
224 adns__update_expires(qu,ttl,now);
225 /* If we find the answer section truncated after this point we restart
226 * the query at the CNAME; if beforehand then we obviously have to use
227 * TCP. If there is no truncation we can use the whole answer if
228 * it contains the relevant info.
231 } else if (rrtype == (qu->answer->type & adns_rrt_typemask)) {
234 adns__debug(ads,serv,qu,"ignoring answer RR"
235 " with irrelevant type %d",rrtype);
239 /* We defer handling truncated responses here, in case there was a CNAME
240 * which we could use.
242 if (flg_tc) goto x_truncated;
247 /* Oops, NODATA or NXDOMAIN or perhaps a referral
248 * (which would be a problem) */
250 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records
251 * in authority section */
252 foundsoa= 0; soattl= 0; foundns= 0;
253 for (rri= 0; rri<nscount; rri++) {
255 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
256 &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0);
257 if (st) { adns__query_fail(qu,st); return; }
258 if (rrtype==-1) goto x_truncated;
259 if (rrclass != DNS_CLASS_IN) {
260 adns__diag(ads,serv,qu,
261 "ignoring authority RR with wrong class %d"
262 " (expected IN=%d)", rrclass,DNS_CLASS_IN);
265 if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; }
266 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
269 if (rcode == rcode_nxdomain) {
270 /* We still wanted to look for the SOA so we could find the TTL. */
271 adns__update_expires(qu,soattl,now);
273 if (qu->flags & adns_qf_search && !qu->cname_dgram) {
274 adns__search_next(ads,qu,now);
276 adns__query_fail(qu,adns_s_nxdomain);
281 if (foundsoa || !foundns) {
282 /* Aha ! A NODATA response, good. */
283 adns__update_expires(qu,soattl,now);
284 adns__query_fail(qu,adns_s_nodata);
288 /* Now what ? No relevant answers, no SOA, and at least some NS's.
289 * Looks like a referral. Just one last chance ... if we came across
290 * a CNAME in this datagram then we should probably do our own CNAME
291 * lookup now in the hope that we won't get a referral again.
293 if (cname_here) goto x_restartquery;
295 /* Bloody hell, I thought we asked for recursion ? */
297 adns__diag(ads,serv,qu,"server is not willing"
298 " to do recursive lookups for us");
299 adns__query_fail(qu,adns_s_norecurse);
302 adns__diag(ads,serv,qu,"server thinks"
303 " we didn't ask for recursive lookup");
305 adns__debug(ads,serv,qu,"server claims to do recursion,"
306 " but gave us a referral");
307 adns__query_fail(qu,adns_s_invalidresponse);
312 /* Now, we have some RRs which we wanted. */
314 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->answer->rrsz*wantedrrs);
315 if (!qu->answer->rrs.untyped) {
316 adns__query_fail(qu,adns_s_nomemory);
322 rrsdata= qu->answer->rrs.bytes;
329 pai.nsstart= nsstart;
330 pai.nscount= nscount;
331 pai.arcount= arcount;
334 for (rri=0, nrrs=0; rri<ancount; rri++) {
335 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
336 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
338 assert(!st); assert(rrtype != -1);
339 if (rrclass != DNS_CLASS_IN ||
340 rrtype != (qu->answer->type & adns_rrt_typemask) ||
343 adns__update_expires(qu,ttl,now);
344 st= typei->parse(&pai, rdstart,rdstart+rdlength,
345 rrsdata+nrrs*qu->answer->rrsz);
346 if (st) { adns__query_fail(qu,st); return; }
347 if (rdstart==-1) goto x_truncated;
350 assert(nrrs==wantedrrs);
351 qu->answer->nrrs= nrrs;
353 /* This may have generated some child queries ... */
354 if (qu->children.head) {
355 qu->state= query_childw;
356 LIST_LINK_TAIL(ads->childw,qu);
359 adns__query_done(qu);
365 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
366 adns__query_fail(qu,adns_s_invalidresponse);
369 qu->flags |= adns_qf_usevc;
372 if (qu->cname_dgram) {
373 st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id,
374 qu->cname_dgram,qu->cname_dglen,qu->cname_begin,
375 qu->answer->type, qu->flags);
376 if (st) { adns__query_fail(qu,st); return; }
378 newquery= realloc(qu->query_dgram,qu->vb.used);
379 if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; }
381 qu->query_dgram= newquery;
382 qu->query_dglen= qu->vb.used;
383 memcpy(newquery,qu->vb.buf,qu->vb.used);
386 if (qu->state == query_tcpw) qu->state= query_tosend;
388 adns__reset_preserved(qu);
389 adns__query_send(qu,now);