3 * - main handling and parsing routine for received datagrams
6 * This file is part of adns, which is Copyright (C) 1997, 1998 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, 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, place;
36 const typeinfo *typei;
41 byte *newquery, *rrsdata;
43 if (dglen<DNS_HDRSIZE) {
44 adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
55 assert(cbyte == DNS_HDRSIZE);
67 adns__diag(ads,serv,0,"server sent us a query, not a response");
71 adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
75 adns__diag(ads,serv,0,"server sent reply without quoting our question");
77 } else if (qdcount>1) {
78 adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
82 for (qu= ads->timew.head; qu; qu= nqu) {
84 if (qu->id != id) continue;
85 if (dglen < qu->query_dglen) continue;
86 if (memcmp(qu->query_dgram+DNS_HDRSIZE,
88 qu->query_dglen-DNS_HDRSIZE))
93 if (ads->iflags & adns_if_debug) {
94 adns__vbuf_init(&tempvb);
95 adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s",
96 id, adns__diag_domain(ads,serv,0,&tempvb,adns_qf_anyquote,
97 dgram,dglen,DNS_HDRSIZE));
98 adns__vbuf_free(&tempvb);
102 anstart= qu->query_dglen;
104 LIST_UNLINK(ads->timew,qu);
105 /* We're definitely going to do something with this query now */
111 case rcode_formaterror:
112 adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
113 adns__query_fail(qu,adns_s_serverfaulty);
116 adns__query_fail(qu,adns_s_servfail);
119 adns__warn(ads,serv,qu,"server claims not to implement our query");
120 adns__query_fail(qu,adns_s_notimplemented);
123 adns__warn(ads,serv,qu,"server refused our query");
124 adns__query_fail(qu,adns_s_refused);
127 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
128 adns__query_fail(qu,adns_s_reasonunknown);
132 /* Now, take a look at the answer section, and see if it is complete.
133 * If it has any CNAMEs we stuff them in the answer.
137 for (rri= 0; rri<ancount; rri++) {
139 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
140 &rrtype,&rrclass,&rdlength,&rdstart,
142 if (st) { adns__query_fail(qu,st); return; }
143 if (rrtype == -1) goto x_truncated;
145 if (rrclass != DNS_CLASS_IN) {
146 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
147 rrclass,DNS_CLASS_IN);
151 if (ads->iflags & adns_if_debug) {
152 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
153 adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
154 dgram,dglen,rrstart));
158 if (rrtype == adns_r_cname && /* fixme - implement adns_qf_nocname */
159 (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
160 if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */
161 qu->cname_begin= rdstart;
162 qu->cname_dglen= dglen;
163 st= adns__parse_domain(ads,serv,qu, &qu->vb,qu->flags,
164 dgram,dglen, &rdstart,rdstart+rdlength);
165 if (!qu->vb.used) goto x_truncated;
166 if (st) { adns__query_fail(qu,st); return; }
167 l= strlen(qu->vb.buf)+1;
168 qu->answer->cname= adns__alloc_interim(qu,l);
169 if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nolocalmem); return; }
171 qu->cname_dgram= adns__alloc_mine(qu,dglen);
172 memcpy(qu->cname_dgram,dgram,dglen);
174 memcpy(qu->answer->cname,qu->vb.buf,l);
176 /* If we find the answer section truncated after this point we restart
177 * the query at the CNAME; if beforehand then we obviously have to use
178 * TCP. If there is no truncation we can use the whole answer if
179 * it contains the relevant info.
182 adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
183 adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
184 dgram,dglen,rdstart),
187 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
190 adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
194 /* We defer handling truncated responses here, in case there was a CNAME
195 * which we could use.
197 if (flg_tc) goto x_truncated;
202 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
204 if (rcode == rcode_nxdomain) {
205 adns__query_fail(qu,adns_s_nxdomain);
209 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
210 foundsoa= 0; foundns= 0;
211 for (rri= 0; rri<nscount; rri++) {
213 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
214 &rrtype,&rrclass,&rdlength,&rdstart, 0);
215 if (st) { adns__query_fail(qu,st); return; }
216 if (rrtype==-1) goto x_truncated;
217 if (rrclass != DNS_CLASS_IN) {
218 adns__diag(ads,serv,qu,
219 "ignoring authority RR with wrong class %d (expected IN=%d)",
220 rrclass,DNS_CLASS_IN);
223 if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; }
224 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
227 if (foundsoa || !foundns) {
228 /* Aha ! A NODATA response, good. */
229 adns__query_fail(qu,adns_s_nodata);
233 /* Now what ? No relevant answers, no SOA, and at least some NS's.
234 * Looks like a referral. Just one last chance ... if we came across
235 * a CNAME in this datagram then we should probably do our own CNAME
236 * lookup now in the hope that we won't get a referral again.
238 if (cname_here) goto x_restartquery;
240 /* Bloody hell, I thought we asked for recursion ? */
242 adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
245 adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
246 adns__query_fail(qu,adns_s_norecurse);
248 adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
249 adns__query_fail(qu,adns_s_serverfaulty);
254 /* Now, we have some RRs which we wanted. */
256 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
257 if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nolocalmem); return; }
262 rrsdata= qu->answer->rrs.bytes;
264 if (typei->diff_needswap) {
265 if (!adns__vbuf_ensure(&qu->vb,typei->rrsz)) {
266 adns__query_fail(qu,adns_s_nolocalmem);
272 for (rri=0; rri<ancount; rri++) {
273 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
274 &rrtype,&rrclass,&rdlength,&rdstart,
276 assert(!st); assert(rrtype != -1);
277 if (rrclass != DNS_CLASS_IN ||
278 rrtype != (qu->typei->type & adns__rrt_typemask) ||
281 st= typei->parse(qu,serv, dgram,dglen, rdstart,rdstart+rdlength,
282 rrsdata+nrrs*typei->rrsz);
283 if (st) { adns__query_fail(qu,st); return; }
284 if (rdstart==-1) goto x_truncated;
286 if (typei->diff_needswap) {
288 place>0 && typei->diff_needswap(rrsdata+(place-1)*typei->rrsz,
289 rrsdata+nrrs*typei->rrsz);
292 memcpy(qu->vb.buf,rrsdata+nrrs*typei->rrsz,typei->rrsz);
293 memmove(rrsdata+(place+1)*typei->rrsz,
294 rrsdata+place*typei->rrsz,
295 (nrrs-place)*typei->rrsz);
296 memcpy(rrsdata+place*typei->rrsz,qu->vb.buf,typei->rrsz);
301 assert(nrrs==wantedrrs);
302 qu->answer->nrrs= nrrs;
304 /* This may have generated some child queries ... */
305 if (qu->children.head) {
306 qu->state= query_child;
307 LIST_LINK_TAIL(ads->childw,qu);
311 adns__query_done(qu);
317 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
318 adns__query_fail(qu,adns_s_serverfaulty);
321 qu->flags |= adns_qf_usevc;
325 if (qu->cname_dgram) {
326 st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id,
327 qu->cname_dgram, qu->cname_dglen, qu->cname_begin,
328 qu->typei->type, qu->flags);
329 if (st) { adns__query_fail(qu,st); return; }
331 newquery= realloc(qu->query_dgram,qu->vb.used);
332 if (!newquery) { adns__query_fail(qu,adns_s_nolocalmem); return; }
334 qu->query_dgram= newquery;
335 qu->query_dglen= qu->vb.used;
336 memcpy(newquery,qu->vb.buf,qu->vb.used);
339 adns__reset_cnameonly(qu);
340 adns__query_udp(qu,now);