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;
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))
94 if (ads->iflags & adns_if_debug) {
95 adns__vbuf_init(&tempvb);
96 adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s",
97 id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE));
98 adns__vbuf_free(&tempvb);
102 anstart= qu->query_dglen;
105 LIST_UNLINK(ads->timew,qu);
106 /* We're definitely going to do something with this query now */
112 case rcode_formaterror:
113 adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
114 adns__query_fail(qu,adns_s_rcodeformaterror);
117 adns__query_fail(qu,adns_s_rcodeservfail);
120 adns__warn(ads,serv,qu,"server claims not to implement our query");
121 adns__query_fail(qu,adns_s_rcodenotimplemented);
124 adns__warn(ads,serv,qu,"server refused our query");
125 adns__query_fail(qu,adns_s_rcoderefused);
128 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
129 adns__query_fail(qu,adns_s_rcodeunknown);
133 /* Now, take a look at the answer section, and see if it is complete.
134 * If it has any CNAMEs we stuff them in the answer.
138 for (rri= 0; rri<ancount; rri++) {
140 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
141 &rrtype,&rrclass,&rdlength,&rdstart,
143 if (st) { adns__query_fail(qu,st); return; }
144 if (rrtype == -1) goto x_truncated;
146 if (rrclass != DNS_CLASS_IN) {
147 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
148 rrclass,DNS_CLASS_IN);
152 if (ads->iflags & adns_if_debug) {
153 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
154 adns__diag_domain(ads,serv,qu, &qu->vb, 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->flags & adns_qf_cname_forbid) {
161 adns__query_fail(qu,adns_s_prohibitedcname);
163 } else if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */
164 qu->cname_begin= rdstart;
165 qu->cname_dglen= dglen;
166 st= adns__parse_domain(ads,serv,qu, &qu->vb,
167 qu->flags & adns_qf_quoteok_cname ? pdf_quoteok : 0,
168 dgram,dglen, &rdstart,rdstart+rdlength);
169 if (!qu->vb.used) goto x_truncated;
170 if (st) { adns__query_fail(qu,st); return; }
171 l= strlen(qu->vb.buf)+1;
172 qu->answer->cname= adns__alloc_interim(qu,l);
173 if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; }
175 qu->cname_dgram= adns__alloc_mine(qu,dglen);
176 memcpy(qu->cname_dgram,dgram,dglen);
178 memcpy(qu->answer->cname,qu->vb.buf,l);
180 /* If we find the answer section truncated after this point we restart
181 * the query at the CNAME; if beforehand then we obviously have to use
182 * TCP. If there is no truncation we can use the whole answer if
183 * it contains the relevant info.
186 adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
187 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart),
190 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
193 adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
197 /* We defer handling truncated responses here, in case there was a CNAME
198 * which we could use.
200 if (flg_tc) goto x_truncated;
205 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
207 if (rcode == rcode_nxdomain) {
208 adns__query_fail(qu,adns_s_nxdomain);
212 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
213 foundsoa= 0; foundns= 0;
214 for (rri= 0; rri<nscount; rri++) {
216 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
217 &rrtype,&rrclass,&rdlength,&rdstart, 0);
218 if (st) { adns__query_fail(qu,st); return; }
219 if (rrtype==-1) goto x_truncated;
220 if (rrclass != DNS_CLASS_IN) {
221 adns__diag(ads,serv,qu,
222 "ignoring authority RR with wrong class %d (expected IN=%d)",
223 rrclass,DNS_CLASS_IN);
226 if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; }
227 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
230 if (foundsoa || !foundns) {
231 /* Aha ! A NODATA response, good. */
232 adns__query_fail(qu,adns_s_nodata);
236 /* Now what ? No relevant answers, no SOA, and at least some NS's.
237 * Looks like a referral. Just one last chance ... if we came across
238 * a CNAME in this datagram then we should probably do our own CNAME
239 * lookup now in the hope that we won't get a referral again.
241 if (cname_here) goto x_restartquery;
243 /* Bloody hell, I thought we asked for recursion ? */
245 adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
248 adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
249 adns__query_fail(qu,adns_s_norecurse);
251 adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
252 adns__query_fail(qu,adns_s_invalidresponse);
257 /* Now, we have some RRs which we wanted. */
259 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
260 if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nomemory); return; }
264 rrsdata= qu->answer->rrs.bytes;
271 pai.nsstart= nsstart;
272 pai.nscount= nscount;
273 pai.arcount= arcount;
276 for (rri=0, nrrs=0; rri<ancount; rri++) {
277 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
278 &rrtype,&rrclass,&rdlength,&rdstart,
280 assert(!st); assert(rrtype != -1);
281 if (rrclass != DNS_CLASS_IN ||
282 rrtype != (qu->typei->type & adns__rrt_typemask) ||
285 st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz);
286 if (st) { adns__query_fail(qu,st); return; }
287 if (rdstart==-1) goto x_truncated;
290 assert(nrrs==wantedrrs);
291 qu->answer->nrrs= nrrs;
293 /* This may have generated some child queries ... */
294 if (qu->children.head) {
295 qu->state= query_child;
296 LIST_LINK_TAIL(ads->childw,qu);
300 adns__query_done(qu);
306 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
307 adns__query_fail(qu,adns_s_invalidresponse);
310 qu->flags |= adns_qf_usevc;
314 if (qu->cname_dgram) {
315 st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id,
316 qu->cname_dgram, qu->cname_dglen, qu->cname_begin,
317 qu->typei->type, qu->flags);
318 if (st) { adns__query_fail(qu,st); return; }
320 newquery= realloc(qu->query_dgram,qu->vb.used);
321 if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; }
323 qu->query_dgram= newquery;
324 qu->query_dglen= qu->vb.used;
325 memcpy(newquery,qu->vb.buf,qu->vb.used);
328 adns__reset_cnameonly(qu);
329 adns__query_udp(qu,now);