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.
25 static void cname_recurse(adns_state ads, adns_query qu, adns_queryflags xflags) {
29 void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
30 int serv, struct timeval now) {
31 int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns;
32 int id, f1, f2, qdcount, ancount, nscount, arcount, flg_ra, flg_rd, flg_tc, opcode;
33 int rrtype, rrclass, rdlength, rdstart, ownermatched, ownerstart;
34 int anstart, nsstart, arstart;
40 if (dglen<DNS_HDRSIZE) {
41 adns__diag(ads,serv,"received datagram too short for message header (%d)",dglen);
51 assert(cbyte == DNS_HDRSIZE);
61 adns__diag(ads,serv,"server sent us a query, not a response");
65 adns__diag(ads,serv,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
69 adns__diag(ads,serv,"server sent reply without quoting our question");
71 } else if (qdcount>1) {
72 adns__diag(ads,serv,"server claimed to answer %d questions with one message",
76 for (qu= ads->timew.head; qu; qu= nqu) {
78 if (qu->id != id) continue;
79 if (dglen < qu->querylen) continue;
80 if (memcmp(qu->querymsg+DNS_HDRSIZE,dgram+DNS_HDRSIZE,qu->querylen-DNS_HDRSIZE))
84 assert(qu->cnameoff == -1);
85 anstart= qu->querylen;
87 adns__debug(ads,serv,"reply not found (id=%02x)",id);
91 LIST_UNLINK(ads->timew,qu);
92 /* We're definitely going to do something with this query now */
98 case rcode_formaterror:
99 adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
100 adns__query_fail(ads,qu,adns_s_serverfaulty);
103 adns__query_fail(ads,qu,adns_s_servfail);
106 adns__warn(ads,serv,qu,"server claims not to implement our query");
107 adns__query_fail(ads,qu,adns_s_notimplemented);
110 adns__warn(ads,serv,qu,"server refused our query");
111 adns__query_fail(ads,qu,adns_s_refused);
114 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
115 adns__query_fail(ads,qu,adns_s_reasonunknown);
119 /* Now, take a look at the answer section, and see if it is complete.
120 * If it has any CNAMEs we stuff them in the answer.
123 for (rri= 0; rri<ancount; rri++) {
125 if (qu->cname_dgram >= 0) {
126 st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
127 &rrtype,&rrclass,&rdlength,&rdstart,
128 qu->cname_dgram,qu->cname_dglen,qu->cname_begin, &ownermatched);
130 st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
131 &rrtype,&rrclass,&rdlength,&rdstart,
132 qu->querymsg,qu->querylen,DNS_HDRSIZE, &ownermatched);
134 if (st) adns__query_fail(ads,qu,st);
135 if (rrtype == -1) goto x_truncated;
137 if (rrclass != DNS_CLASS_IN) {
138 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
139 rrclass,DNS_CLASS_IN);
143 if (ads->iflags & adns_if_debug) {
144 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
145 adns__diag_domain(ads,serv,&qu->vb,qu->flags,
146 dgram,dglen,rrstart,dglen));
150 if (rrtype == adns_r_cname &&
151 (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
152 if (!qu->cname_str) { /* Ignore second and subsequent CNAMEs */
153 qu->cname_begin= rdstart;
154 qu->cname_dgram= dgram;
155 qu->cname_dglen= dglen;
156 st= adns__parse_domain(ads,serv,&qu->vb,qu->flags,
157 dgram,dglen, &rdstart,rdstart+rdlength);
158 if (!vb.used) goto x_truncated;
159 if (st) { adns__query_fail(ads,qu,st); return; }
160 qu->answer->cname= adns__savestring(qu);
161 if (!qu->answer->cname) return;
162 /* If we find the answer section truncated after this point we restart
163 * the query at the CNAME; if beforehand then we obviously have to use
164 * TCP. If there is no truncation we can use the whole answer if
165 * it contains the relevant info.
168 adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
169 adns__diag_domain(ads,serv,&qu->vb,qu->flags,
170 dgram,dglen, rdstart,rdstart+rdlength),
173 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
176 adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
180 /* If we got here then the answer section is intact. */
184 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
186 if (rcode == rcode_nxdomain) {
187 adns__query_finish(ads,qu,adns_s_nxdomain);
191 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
192 foundsoa= 0; foundns= 0;
193 for (rri= 0; rri<nscount; rri++) {
195 st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
196 &rrtype,&rrclass,&rdlength,&rdstart,
198 if (st) { adns__query_fail(ads,qu,st); return; }
199 if (rrtype==-1) goto x_truncated;
200 if (rrclass != DNS_CLASS_IN) {
201 adns__diag(ads,serv,qu,
202 "ignoring authority RR with wrong class %d (expected IN=%d)",
203 rrclass,DNS_CLASS_IN);
206 if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; }
207 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
210 if (foundsoa || !foundns) {
211 /* Aha ! A NODATA response, good. */
212 adns__query_finish(ads,qu,adns_s_nodata);
216 /* Now what ? No relevant answers, no SOA, and at least some NS's.
217 * Looks like a referral. Just one last chance ... if we came across
218 * a CNAME in this datagram then we should probably do our own CNAME
219 * lookup now in the hope that we won't get a referral again.
221 if (qu->cname_dgram == dgram) { cname_recurse(ads,qu,0); return; }
223 /* Bloody hell, I thought we asked for recursion ? */
225 adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
228 adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
229 adns__query_fail(ads,qu,adns_s_norecurse);
231 adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
232 adns__query_fail(ads,qu,adns_s_serverfaulty);
237 /* Now, we have some RRs which we wanted. */
239 qu->ans->rrs= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
240 if (!qu->ans->rrs) return;
244 for (rri=0; rri<ancount; rri++) {
245 if (qu->cname_dgram >= 0) {
246 st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
247 &rrtype,&rrclass,&rdlength,&rdstart,
248 qu->cname_dgram,qu->cname_dglen,qu->cname_begin, &ownermatched);
250 st= adns__findrr(ads,serv, dgram,dglen,&cbyte,
251 &rrtype,&rrclass,&rdlength,&rdstart,
252 qu->querymsg,qu->querylen,DNS_HDRSIZE, &ownermatched);
254 assert(!st); assert(rrtype != -1);
255 if (rrclass != DNS_CLASS_IN ||
256 rrtype != (qu->typei->type & adns__rrt_typemask) ||
259 assert(qu->ans->nrrs<wantedrrs);
260 st= qu->typei->parse(ads,qu,serv,
261 dgram,dglen, &rdstart,rdstart+rdlength,
262 qu->ans->rrs.bytes+qu->ans->nrrs*quj->typei->rrsz);
263 if (st) { adns__query_fail(ads,qu,st); return; }
264 if (rdstart==-1) goto x_truncated;
267 /* This may have generated some child queries ... */
268 if (qu->children.head) {
269 qu->state= query_child;
270 LIST_LINK_TAIL(ads->childw,qu);
274 adns__query_finish(ads,qu,adns_s_ok);
279 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
280 adns__query_fail(ads,qu,adns_s_serverfaulty);
283 if (qu->cname_dgram) { cname_recurse(ads,qu,adns_qf_usevc); return; }
284 adns__reset_cnameonly(ads,qu);
285 qu->flags |= adns_qf_usevc;
286 adns__query_udp(ads,qu,now);