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.
28 void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
29 int serv, int viatcp, struct timeval now) {
30 int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here;
31 int id, f1, f2, qdcount, ancount, nscount, arcount;
32 int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
33 int rrtype, rrclass, rdlength, rdstart;
34 int anstart, nsstart, arstart;
35 int ownermatched, l, nrrs;
36 unsigned long ttl, soattl;
37 const typeinfo *typei;
42 byte *newquery, *rrsdata;
45 if (dglen<DNS_HDRSIZE) {
46 adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
57 assert(cbyte == DNS_HDRSIZE);
69 adns__diag(ads,serv,0,"server sent us a query, not a response");
73 adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
77 adns__diag(ads,serv,0,"server sent reply without quoting our question");
79 } else if (qdcount>1) {
80 adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
84 for (qu= ads->timew.head; qu; qu= nqu) {
86 if (qu->id != id) continue;
87 if (dglen < qu->query_dglen) continue;
88 if (memcmp(qu->query_dgram+DNS_HDRSIZE,
90 qu->query_dglen-DNS_HDRSIZE))
93 if (qu->state != query_tcpsent) continue;
95 if (qu->state != query_tosend) continue;
96 if (!(qu->udpsent & (1<<serv))) continue;
101 if (ads->iflags & adns_if_debug) {
102 adns__vbuf_init(&tempvb);
103 adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s",
104 id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE));
105 adns__vbuf_free(&tempvb);
109 anstart= qu->query_dglen;
112 LIST_UNLINK(ads->timew,qu);
113 /* We're definitely going to do something with this query now */
119 case rcode_formaterror:
120 adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
121 adns__query_fail(qu,adns_s_rcodeformaterror);
124 adns__query_fail(qu,adns_s_rcodeservfail);
127 adns__warn(ads,serv,qu,"server claims not to implement our query");
128 adns__query_fail(qu,adns_s_rcodenotimplemented);
131 adns__warn(ads,serv,qu,"server refused our query");
132 adns__query_fail(qu,adns_s_rcoderefused);
135 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
136 adns__query_fail(qu,adns_s_rcodeunknown);
140 /* Now, take a look at the answer section, and see if it is complete.
141 * If it has any CNAMEs we stuff them in the answer.
145 for (rri= 0; rri<ancount; rri++) {
147 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
148 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
150 if (st) { adns__query_fail(qu,st); return; }
151 if (rrtype == -1) goto x_truncated;
153 if (rrclass != DNS_CLASS_IN) {
154 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
155 rrclass,DNS_CLASS_IN);
159 if (ads->iflags & adns_if_debug) {
160 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
161 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rrstart));
165 if (rrtype == adns_r_cname &&
166 (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
167 if (qu->flags & adns_qf_cname_forbid) {
168 adns__query_fail(qu,adns_s_prohibitedcname);
170 } else if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */
171 qu->cname_begin= rdstart;
172 qu->cname_dglen= dglen;
173 st= adns__parse_domain(ads,serv,qu, &qu->vb,
174 qu->flags & adns_qf_quoteok_cname ? pdf_quoteok : 0,
175 dgram,dglen, &rdstart,rdstart+rdlength);
176 if (!qu->vb.used) goto x_truncated;
177 if (st) { adns__query_fail(qu,st); return; }
178 l= strlen(qu->vb.buf)+1;
179 qu->answer->cname= adns__alloc_preserved(qu,l);
180 if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; }
182 qu->cname_dgram= adns__alloc_mine(qu,dglen);
183 memcpy(qu->cname_dgram,dgram,dglen);
185 memcpy(qu->answer->cname,qu->vb.buf,l);
187 adns__update_expires(qu,ttl,now);
188 /* If we find the answer section truncated after this point we restart
189 * the query at the CNAME; if beforehand then we obviously have to use
190 * TCP. If there is no truncation we can use the whole answer if
191 * it contains the relevant info.
194 adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
195 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart),
198 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
201 adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
205 /* We defer handling truncated responses here, in case there was a CNAME
206 * which we could use.
208 if (flg_tc) goto x_truncated;
213 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
215 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
216 foundsoa= 0; soattl= 0; foundns= 0;
217 for (rri= 0; rri<nscount; rri++) {
219 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
220 &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0);
221 if (st) { adns__query_fail(qu,st); return; }
222 if (rrtype==-1) goto x_truncated;
223 if (rrclass != DNS_CLASS_IN) {
224 adns__diag(ads,serv,qu,
225 "ignoring authority RR with wrong class %d (expected IN=%d)",
226 rrclass,DNS_CLASS_IN);
229 if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; }
230 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
233 if (rcode == rcode_nxdomain) {
234 /* We still wanted to look for the SOA so we could find the TTL. */
235 adns__update_expires(qu,soattl,now);
237 if (qu->flags & adns_qf_search) {
238 adns__search_next(ads,qu,now);
240 adns__query_fail(qu,adns_s_nxdomain);
245 if (foundsoa || !foundns) {
246 /* Aha ! A NODATA response, good. */
247 adns__update_expires(qu,soattl,now);
248 adns__query_fail(qu,adns_s_nodata);
252 /* Now what ? No relevant answers, no SOA, and at least some NS's.
253 * Looks like a referral. Just one last chance ... if we came across
254 * a CNAME in this datagram then we should probably do our own CNAME
255 * lookup now in the hope that we won't get a referral again.
257 if (cname_here) goto x_restartquery;
259 /* Bloody hell, I thought we asked for recursion ? */
261 adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
264 adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
265 adns__query_fail(qu,adns_s_norecurse);
267 adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
268 adns__query_fail(qu,adns_s_invalidresponse);
273 /* Now, we have some RRs which we wanted. */
275 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
276 if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nomemory); return; }
280 rrsdata= qu->answer->rrs.bytes;
287 pai.nsstart= nsstart;
288 pai.nscount= nscount;
289 pai.arcount= arcount;
292 for (rri=0, nrrs=0; rri<ancount; rri++) {
293 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
294 &rrtype,&rrclass,&ttl, &rdlength,&rdstart,
296 assert(!st); assert(rrtype != -1);
297 if (rrclass != DNS_CLASS_IN ||
298 rrtype != (qu->typei->type & adns__rrt_typemask) ||
301 adns__update_expires(qu,ttl,now);
302 st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz);
303 if (st) { adns__query_fail(qu,st); return; }
304 if (rdstart==-1) goto x_truncated;
307 assert(nrrs==wantedrrs);
308 qu->answer->nrrs= nrrs;
310 /* This may have generated some child queries ... */
311 if (qu->children.head) {
312 qu->state= query_child;
313 LIST_LINK_TAIL(ads->childw,qu);
316 adns__query_done(qu);
322 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
323 adns__query_fail(qu,adns_s_invalidresponse);
326 qu->flags |= adns_qf_usevc;
329 if (qu->cname_dgram) {
330 st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id,
331 qu->cname_dgram, qu->cname_dglen, qu->cname_begin,
332 qu->typei->type, qu->flags);
333 if (st) { adns__query_fail(qu,st); return; }
335 newquery= realloc(qu->query_dgram,qu->vb.used);
336 if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; }
338 qu->query_dgram= newquery;
339 qu->query_dglen= qu->vb.used;
340 memcpy(newquery,qu->vb.buf,qu->vb.used);
343 if (qu->state == query_tcpsent) qu->state= query_tosend;
344 adns__reset_preserved(qu);
345 adns__query_send(qu,now);