3 * - main handling and parsing routine for received datagrams
7 * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
9 * It is part of adns, which is
10 * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
11 * Copyright (C) 1999 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);
81 adns__diag(ads,serv,0,"server sent reply without quoting our question");
83 } else if (qdcount>1) {
84 adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
88 for (qu= ads->timew.head; qu; qu= nqu) {
90 if (qu->id != id) continue;
91 if (dglen < qu->query_dglen) continue;
92 if (memcmp(qu->query_dgram+DNS_HDRSIZE,
94 qu->query_dglen-DNS_HDRSIZE))
97 if (qu->state != query_tcpsent) continue;
99 if (qu->state != query_tosend) continue;
100 if (!(qu->udpsent & (1<<serv))) continue;
105 if (ads->iflags & adns_if_debug) {
106 adns__vbuf_init(&tempvb);
107 adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s",
108 id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE));
109 adns__vbuf_free(&tempvb);
113 anstart= qu->query_dglen;
116 LIST_UNLINK(ads->timew,qu);
117 /* We're definitely going to do something with this query now */
123 case rcode_formaterror:
124 adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
125 adns__query_fail(qu,adns_s_rcodeformaterror);
128 adns__query_fail(qu,adns_s_rcodeservfail);
131 adns__warn(ads,serv,qu,"server claims not to implement our query");
132 adns__query_fail(qu,adns_s_rcodenotimplemented);
135 adns__warn(ads,serv,qu,"server refused our query");
136 adns__query_fail(qu,adns_s_rcoderefused);
139 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
140 adns__query_fail(qu,adns_s_rcodeunknown);
144 /* Now, take a look at the answer section, and see if it is complete.
145 * If it has any CNAMEs we stuff them in the answer.
149 for (rri= 0; rri<ancount; rri++) {
151 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
152 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
154 if (st) { adns__query_fail(qu,st); return; }
155 if (rrtype == -1) goto x_truncated;
157 if (rrclass != DNS_CLASS_IN) {
158 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
159 rrclass,DNS_CLASS_IN);
163 if (ads->iflags & adns_if_debug) {
164 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
165 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rrstart));
169 if (rrtype == adns_r_cname &&
170 (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
171 if (qu->flags & adns_qf_cname_forbid) {
172 adns__query_fail(qu,adns_s_prohibitedcname);
174 } else if (qu->cname_dgram) { /* Ignore second and subsequent CNAME(s) */
175 adns__debug(ads,serv,qu,"allegedly canonical name %s is actually alias for %s",
177 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart));
178 adns__query_fail(qu,adns_s_prohibitedcname);
180 } else if (wantedrrs) { /* Ignore CNAME(s) after RR(s). */
181 adns__debug(ads,serv,qu,"ignoring CNAME (to %s) coexisting with RR",
182 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart));
184 qu->cname_begin= rdstart;
185 qu->cname_dglen= dglen;
186 st= adns__parse_domain(ads,serv,qu, &qu->vb,
187 qu->flags & adns_qf_quoteok_cname ? pdf_quoteok : 0,
188 dgram,dglen, &rdstart,rdstart+rdlength);
189 if (!qu->vb.used) goto x_truncated;
190 if (st) { adns__query_fail(qu,st); return; }
191 l= strlen(qu->vb.buf)+1;
192 qu->answer->cname= adns__alloc_preserved(qu,l);
193 if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; }
195 qu->cname_dgram= adns__alloc_mine(qu,dglen);
196 memcpy(qu->cname_dgram,dgram,dglen);
198 memcpy(qu->answer->cname,qu->vb.buf,l);
200 adns__update_expires(qu,ttl,now);
201 /* If we find the answer section truncated after this point we restart
202 * the query at the CNAME; if beforehand then we obviously have to use
203 * TCP. If there is no truncation we can use the whole answer if
204 * it contains the relevant info.
207 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
210 adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
214 /* We defer handling truncated responses here, in case there was a CNAME
215 * which we could use.
217 if (flg_tc) goto x_truncated;
222 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
224 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
225 foundsoa= 0; soattl= 0; foundns= 0;
226 for (rri= 0; rri<nscount; rri++) {
228 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
229 &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0);
230 if (st) { adns__query_fail(qu,st); return; }
231 if (rrtype==-1) goto x_truncated;
232 if (rrclass != DNS_CLASS_IN) {
233 adns__diag(ads,serv,qu,
234 "ignoring authority RR with wrong class %d (expected IN=%d)",
235 rrclass,DNS_CLASS_IN);
238 if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; }
239 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
242 if (rcode == rcode_nxdomain) {
243 /* We still wanted to look for the SOA so we could find the TTL. */
244 adns__update_expires(qu,soattl,now);
246 if (qu->flags & adns_qf_search) {
247 adns__search_next(ads,qu,now);
249 adns__query_fail(qu,adns_s_nxdomain);
254 if (foundsoa || !foundns) {
255 /* Aha ! A NODATA response, good. */
256 adns__update_expires(qu,soattl,now);
257 adns__query_fail(qu,adns_s_nodata);
261 /* Now what ? No relevant answers, no SOA, and at least some NS's.
262 * Looks like a referral. Just one last chance ... if we came across
263 * a CNAME in this datagram then we should probably do our own CNAME
264 * lookup now in the hope that we won't get a referral again.
266 if (cname_here) goto x_restartquery;
268 /* Bloody hell, I thought we asked for recursion ? */
270 adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
273 adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
274 adns__query_fail(qu,adns_s_norecurse);
276 adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
277 adns__query_fail(qu,adns_s_invalidresponse);
282 /* Now, we have some RRs which we wanted. */
284 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
285 if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nomemory); return; }
289 rrsdata= qu->answer->rrs.bytes;
296 pai.nsstart= nsstart;
297 pai.nscount= nscount;
298 pai.arcount= arcount;
301 for (rri=0, nrrs=0; rri<ancount; rri++) {
302 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
303 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
305 assert(!st); assert(rrtype != -1);
306 if (rrclass != DNS_CLASS_IN ||
307 rrtype != (qu->typei->type & adns__rrt_typemask) ||
310 adns__update_expires(qu,ttl,now);
311 st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz);
312 if (st) { adns__query_fail(qu,st); return; }
313 if (rdstart==-1) goto x_truncated;
316 assert(nrrs==wantedrrs);
317 qu->answer->nrrs= nrrs;
319 /* This may have generated some child queries ... */
320 if (qu->children.head) {
321 qu->state= query_child;
322 LIST_LINK_TAIL(ads->childw,qu);
325 adns__query_done(qu);
331 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
332 adns__query_fail(qu,adns_s_invalidresponse);
335 qu->flags |= adns_qf_usevc;
338 if (qu->cname_dgram) {
339 st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id,
340 qu->cname_dgram, qu->cname_dglen, qu->cname_begin,
341 qu->typei->type, qu->flags);
342 if (st) { adns__query_fail(qu,st); return; }
344 newquery= realloc(qu->query_dgram,qu->vb.used);
345 if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; }
347 qu->query_dgram= newquery;
348 qu->query_dglen= qu->vb.used;
349 memcpy(newquery,qu->vb.buf,qu->vb.used);
352 if (qu->state == query_tcpsent) qu->state= query_tosend;
353 adns__reset_preserved(qu);
354 adns__query_send(qu,now);