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_query qu, adns_queryflags xflags) {
26 adns__diag(qu->ads,-1,qu,"cname following not implemented fixme");
27 adns__query_fail(qu,adns_s_notimplemented);
30 void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
31 int serv, struct timeval now) {
32 int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here;
33 int id, f1, f2, qdcount, ancount, nscount, arcount;
34 int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
35 int rrtype, rrclass, rdlength, rdstart, ownermatched, l;
36 int anstart, nsstart, arstart;
42 if (dglen<DNS_HDRSIZE) {
43 adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
54 assert(cbyte == DNS_HDRSIZE);
66 adns__diag(ads,serv,0,"server sent us a query, not a response");
70 adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
74 adns__diag(ads,serv,0,"server sent reply without quoting our question");
76 } else if (qdcount>1) {
77 adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
81 for (qu= ads->timew.head; qu; qu= nqu) {
83 if (qu->id != id) continue;
84 if (dglen < qu->query_dglen) continue;
85 if (memcmp(qu->query_dgram+DNS_HDRSIZE,
87 qu->query_dglen-DNS_HDRSIZE))
92 if (ads->iflags & adns_if_debug) {
93 adns__vbuf_init(&tempvb);
94 adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s",
95 id, adns__diag_domain(ads,serv,0,&tempvb,adns_qf_anyquote,
96 dgram,dglen,DNS_HDRSIZE));
97 adns__vbuf_free(&tempvb);
101 anstart= qu->query_dglen;
103 LIST_UNLINK(ads->timew,qu);
104 /* We're definitely going to do something with this query now */
110 case rcode_formaterror:
111 adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
112 adns__query_fail(qu,adns_s_serverfaulty);
115 adns__query_fail(qu,adns_s_servfail);
118 adns__warn(ads,serv,qu,"server claims not to implement our query");
119 adns__query_fail(qu,adns_s_notimplemented);
122 adns__warn(ads,serv,qu,"server refused our query");
123 adns__query_fail(qu,adns_s_refused);
126 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
127 adns__query_fail(qu,adns_s_reasonunknown);
131 /* Now, take a look at the answer section, and see if it is complete.
132 * If it has any CNAMEs we stuff them in the answer.
136 for (rri= 0; rri<ancount; rri++) {
138 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
139 &rrtype,&rrclass,&rdlength,&rdstart,
141 if (st) { adns__query_fail(qu,st); return; }
142 if (rrtype == -1) goto x_truncated;
144 if (rrclass != DNS_CLASS_IN) {
145 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
146 rrclass,DNS_CLASS_IN);
150 if (ads->iflags & adns_if_debug) {
151 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
152 adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
153 dgram,dglen,rrstart));
157 if (rrtype == adns_r_cname &&
158 (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
159 if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */
160 qu->cname_dgram= adns__alloc_mine(qu,dglen);
161 if (!qu->cname_dgram) return;
162 qu->cname_begin= rdstart;
163 qu->cname_dglen= dglen;
164 st= adns__parse_domain(ads,serv,qu, &qu->vb,qu->flags,
165 dgram,dglen, &rdstart,rdstart+rdlength);
166 if (!qu->vb.used) goto x_truncated;
167 if (st) { adns__query_fail(qu,st); return; }
168 l= strlen(qu->vb.buf)+1;
169 qu->answer->cname= adns__alloc_interim(qu,l);
170 if (!qu->answer->cname) return;
171 memcpy(qu->answer->cname,qu->vb.buf,l);
173 /* If we find the answer section truncated after this point we restart
174 * the query at the CNAME; if beforehand then we obviously have to use
175 * TCP. If there is no truncation we can use the whole answer if
176 * it contains the relevant info.
179 adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
180 adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
181 dgram,dglen,rdstart),
184 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
187 adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
191 /* If we got here then the answer section is intact. */
195 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
197 if (rcode == rcode_nxdomain) {
198 adns__query_fail(qu,adns_s_nxdomain);
202 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
203 foundsoa= 0; foundns= 0;
204 for (rri= 0; rri<nscount; rri++) {
206 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
207 &rrtype,&rrclass,&rdlength,&rdstart, 0);
208 if (st) { adns__query_fail(qu,st); return; }
209 if (rrtype==-1) goto x_truncated;
210 if (rrclass != DNS_CLASS_IN) {
211 adns__diag(ads,serv,qu,
212 "ignoring authority RR with wrong class %d (expected IN=%d)",
213 rrclass,DNS_CLASS_IN);
216 if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; }
217 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
220 if (foundsoa || !foundns) {
221 /* Aha ! A NODATA response, good. */
222 adns__query_fail(qu,adns_s_nodata);
226 /* Now what ? No relevant answers, no SOA, and at least some NS's.
227 * Looks like a referral. Just one last chance ... if we came across
228 * a CNAME in this datagram then we should probably do our own CNAME
229 * lookup now in the hope that we won't get a referral again.
231 if (cname_here) { cname_recurse(qu,0); return; }
233 /* Bloody hell, I thought we asked for recursion ? */
235 adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
238 adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
239 adns__query_fail(qu,adns_s_norecurse);
241 adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
242 adns__query_fail(qu,adns_s_serverfaulty);
247 /* Now, we have some RRs which we wanted. */
249 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
250 if (!qu->answer->rrs.untyped) return;
254 for (rri=0; rri<ancount; rri++) {
255 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
256 &rrtype,&rrclass,&rdlength,&rdstart,
258 assert(!st); assert(rrtype != -1);
259 if (rrclass != DNS_CLASS_IN ||
260 rrtype != (qu->typei->type & adns__rrt_typemask) ||
263 assert(qu->answer->nrrs<wantedrrs);
264 st= qu->typei->parse(qu,serv,
265 dgram,dglen, rdstart,rdstart+rdlength,
266 qu->answer->rrs.bytes+qu->answer->nrrs*qu->typei->rrsz);
267 if (st) { adns__query_fail(qu,st); return; }
268 if (rdstart==-1) goto x_truncated;
272 /* This may have generated some child queries ... */
273 if (qu->children.head) {
274 qu->state= query_child;
275 LIST_LINK_TAIL(ads->childw,qu);
279 adns__query_done(qu);
284 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
285 adns__query_fail(qu,adns_s_serverfaulty);
288 if (qu->cname_dgram) { cname_recurse(qu,adns_qf_usevc); return; }
289 adns__reset_cnameonly(qu);
290 qu->flags |= adns_qf_usevc;
291 adns__query_udp(qu,now);