3 * - main handling and parsing routine for received datagrams
6 * This file is part of adns, which is Copyright (C) 1997-1999 Ian Jackson
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)
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.
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.
27 void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
28 int serv, int viatcp, struct timeval now) {
29 int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here;
30 int id, f1, f2, qdcount, ancount, nscount, arcount;
31 int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
32 int rrtype, rrclass, rdlength, rdstart;
33 int anstart, nsstart, arstart;
34 int ownermatched, l, nrrs;
35 unsigned long ttl, soattl;
36 const typeinfo *typei;
41 byte *newquery, *rrsdata;
44 if (dglen<DNS_HDRSIZE) {
45 adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
56 assert(cbyte == DNS_HDRSIZE);
68 adns__diag(ads,serv,0,"server sent us a query, not a response");
72 adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
76 adns__diag(ads,serv,0,"server sent reply without quoting our question");
78 } else if (qdcount>1) {
79 adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
83 for (qu= ads->timew.head; qu; qu= nqu) {
85 if (qu->id != id) continue;
86 if (dglen < qu->query_dglen) continue;
87 if (memcmp(qu->query_dgram+DNS_HDRSIZE,
89 qu->query_dglen-DNS_HDRSIZE))
92 if (qu->state != query_tcpsent) continue;
94 if (qu->state != query_tosend) continue;
95 if (!(qu->udpsent & (1<<serv))) continue;
100 if (ads->iflags & adns_if_debug) {
101 adns__vbuf_init(&tempvb);
102 adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s",
103 id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE));
104 adns__vbuf_free(&tempvb);
108 anstart= qu->query_dglen;
111 LIST_UNLINK(ads->timew,qu);
112 /* We're definitely going to do something with this query now */
118 case rcode_formaterror:
119 adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
120 adns__query_fail(qu,adns_s_rcodeformaterror);
123 adns__query_fail(qu,adns_s_rcodeservfail);
126 adns__warn(ads,serv,qu,"server claims not to implement our query");
127 adns__query_fail(qu,adns_s_rcodenotimplemented);
130 adns__warn(ads,serv,qu,"server refused our query");
131 adns__query_fail(qu,adns_s_rcoderefused);
134 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
135 adns__query_fail(qu,adns_s_rcodeunknown);
139 /* Now, take a look at the answer section, and see if it is complete.
140 * If it has any CNAMEs we stuff them in the answer.
144 for (rri= 0; rri<ancount; rri++) {
146 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
147 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
149 if (st) { adns__query_fail(qu,st); return; }
150 if (rrtype == -1) goto x_truncated;
152 if (rrclass != DNS_CLASS_IN) {
153 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
154 rrclass,DNS_CLASS_IN);
158 if (ads->iflags & adns_if_debug) {
159 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
160 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rrstart));
164 if (rrtype == adns_r_cname &&
165 (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
166 if (qu->flags & adns_qf_cname_forbid) {
167 adns__query_fail(qu,adns_s_prohibitedcname);
169 } else if (qu->cname_dgram) { /* Ignore second and subsequent CNAME(s) */
170 adns__debug(ads,serv,qu,"allegedly canonical name %s is actually alias for %s",
172 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart));
173 adns__query_fail(qu,adns_s_prohibitedcname);
175 } else if (wantedrrs) { /* Ignore CNAME(s) after RR(s). */
176 adns__debug(ads,serv,qu,"ignoring CNAME (to %s) coexisting with RR",
177 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart));
179 qu->cname_begin= rdstart;
180 qu->cname_dglen= dglen;
181 st= adns__parse_domain(ads,serv,qu, &qu->vb,
182 qu->flags & adns_qf_quoteok_cname ? pdf_quoteok : 0,
183 dgram,dglen, &rdstart,rdstart+rdlength);
184 if (!qu->vb.used) goto x_truncated;
185 if (st) { adns__query_fail(qu,st); return; }
186 l= strlen(qu->vb.buf)+1;
187 qu->answer->cname= adns__alloc_preserved(qu,l);
188 if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; }
190 qu->cname_dgram= adns__alloc_mine(qu,dglen);
191 memcpy(qu->cname_dgram,dgram,dglen);
193 memcpy(qu->answer->cname,qu->vb.buf,l);
195 adns__update_expires(qu,ttl,now);
196 /* If we find the answer section truncated after this point we restart
197 * the query at the CNAME; if beforehand then we obviously have to use
198 * TCP. If there is no truncation we can use the whole answer if
199 * it contains the relevant info.
202 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
205 adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
209 /* We defer handling truncated responses here, in case there was a CNAME
210 * which we could use.
212 if (flg_tc) goto x_truncated;
217 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
219 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
220 foundsoa= 0; soattl= 0; foundns= 0;
221 for (rri= 0; rri<nscount; rri++) {
223 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
224 &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0);
225 if (st) { adns__query_fail(qu,st); return; }
226 if (rrtype==-1) goto x_truncated;
227 if (rrclass != DNS_CLASS_IN) {
228 adns__diag(ads,serv,qu,
229 "ignoring authority RR with wrong class %d (expected IN=%d)",
230 rrclass,DNS_CLASS_IN);
233 if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; }
234 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
237 if (rcode == rcode_nxdomain) {
238 /* We still wanted to look for the SOA so we could find the TTL. */
239 adns__update_expires(qu,soattl,now);
241 if (qu->flags & adns_qf_search) {
242 adns__search_next(ads,qu,now);
244 adns__query_fail(qu,adns_s_nxdomain);
249 if (foundsoa || !foundns) {
250 /* Aha ! A NODATA response, good. */
251 adns__update_expires(qu,soattl,now);
252 adns__query_fail(qu,adns_s_nodata);
256 /* Now what ? No relevant answers, no SOA, and at least some NS's.
257 * Looks like a referral. Just one last chance ... if we came across
258 * a CNAME in this datagram then we should probably do our own CNAME
259 * lookup now in the hope that we won't get a referral again.
261 if (cname_here) goto x_restartquery;
263 /* Bloody hell, I thought we asked for recursion ? */
265 adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
268 adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
269 adns__query_fail(qu,adns_s_norecurse);
271 adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
272 adns__query_fail(qu,adns_s_invalidresponse);
277 /* Now, we have some RRs which we wanted. */
279 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
280 if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nomemory); return; }
284 rrsdata= qu->answer->rrs.bytes;
291 pai.nsstart= nsstart;
292 pai.nscount= nscount;
293 pai.arcount= arcount;
296 for (rri=0, nrrs=0; rri<ancount; rri++) {
297 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
298 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
300 assert(!st); assert(rrtype != -1);
301 if (rrclass != DNS_CLASS_IN ||
302 rrtype != (qu->typei->type & adns__rrt_typemask) ||
305 adns__update_expires(qu,ttl,now);
306 st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz);
307 if (st) { adns__query_fail(qu,st); return; }
308 if (rdstart==-1) goto x_truncated;
311 assert(nrrs==wantedrrs);
312 qu->answer->nrrs= nrrs;
314 /* This may have generated some child queries ... */
315 if (qu->children.head) {
316 qu->state= query_child;
317 LIST_LINK_TAIL(ads->childw,qu);
320 adns__query_done(qu);
326 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
327 adns__query_fail(qu,adns_s_invalidresponse);
330 qu->flags |= adns_qf_usevc;
333 if (qu->cname_dgram) {
334 st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id,
335 qu->cname_dgram, qu->cname_dglen, qu->cname_begin,
336 qu->typei->type, qu->flags);
337 if (st) { adns__query_fail(qu,st); return; }
339 newquery= realloc(qu->query_dgram,qu->vb.used);
340 if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; }
342 qu->query_dgram= newquery;
343 qu->query_dglen= qu->vb.used;
344 memcpy(newquery,qu->vb.buf,qu->vb.used);
347 if (qu->state == query_tcpsent) qu->state= query_tosend;
348 adns__reset_preserved(qu);
349 adns__query_send(qu,now);