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) {
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;
33 int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
34 int rrtype, rrclass, rdlength, rdstart, ownermatched, l;
35 int anstart, nsstart, arstart;
40 if (dglen<DNS_HDRSIZE) {
41 adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
51 assert(cbyte == DNS_HDRSIZE);
61 adns__diag(ads,serv,0,"server sent us a query, not a response");
65 adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
69 adns__diag(ads,serv,0,"server sent reply without quoting our question");
71 } else if (qdcount>1) {
72 adns__diag(ads,serv,0,"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->query_dglen) continue;
80 if (memcmp(qu->query_dgram+DNS_HDRSIZE,
82 qu->query_dglen-DNS_HDRSIZE))
86 anstart= qu->query_dglen;
88 adns__debug(ads,serv,0,"reply not found (id=%02x)",id);
92 LIST_UNLINK(ads->timew,qu);
93 /* We're definitely going to do something with this query now */
99 case rcode_formaterror:
100 adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
101 adns__query_fail(qu,adns_s_serverfaulty);
104 adns__query_fail(qu,adns_s_servfail);
107 adns__warn(ads,serv,qu,"server claims not to implement our query");
108 adns__query_fail(qu,adns_s_notimplemented);
111 adns__warn(ads,serv,qu,"server refused our query");
112 adns__query_fail(qu,adns_s_refused);
115 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
116 adns__query_fail(qu,adns_s_reasonunknown);
120 /* Now, take a look at the answer section, and see if it is complete.
121 * If it has any CNAMEs we stuff them in the answer.
124 for (rri= 0; rri<ancount; rri++) {
126 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
127 &rrtype,&rrclass,&rdlength,&rdstart,
129 if (st) adns__query_fail(qu,st);
130 if (rrtype == -1) goto x_truncated;
132 if (rrclass != DNS_CLASS_IN) {
133 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
134 rrclass,DNS_CLASS_IN);
138 if (ads->iflags & adns_if_debug) {
139 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
140 adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
141 dgram,dglen,rrstart));
145 if (rrtype == adns_r_cname &&
146 (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
147 if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */
148 qu->cname_dgram= adns__alloc_mine(qu,dglen);
149 if (!qu->cname_dgram) return;
150 qu->cname_begin= rdstart;
151 qu->cname_dglen= dglen;
152 st= adns__parse_domain(ads,serv,qu, &qu->vb,qu->flags,
153 dgram,dglen, &rdstart,rdstart+rdlength);
154 if (!qu->vb.used) goto x_truncated;
155 if (st) { adns__query_fail(qu,st); return; }
156 l= strlen(qu->vb.buf)+1;
157 qu->answer->cname= adns__alloc_interim(qu,l);
158 if (!qu->answer->cname) return;
159 memcpy(qu->answer->cname,qu->vb.buf,l);
160 /* If we find the answer section truncated after this point we restart
161 * the query at the CNAME; if beforehand then we obviously have to use
162 * TCP. If there is no truncation we can use the whole answer if
163 * it contains the relevant info.
166 adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
167 adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
168 dgram,dglen,rdstart),
171 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
174 adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
178 /* If we got here then the answer section is intact. */
182 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
184 if (rcode == rcode_nxdomain) {
185 adns__query_fail(qu,adns_s_nxdomain);
189 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
190 foundsoa= 0; foundns= 0;
191 for (rri= 0; rri<nscount; rri++) {
193 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
194 &rrtype,&rrclass,&rdlength,&rdstart, 0);
195 if (st) { adns__query_fail(qu,st); return; }
196 if (rrtype==-1) goto x_truncated;
197 if (rrclass != DNS_CLASS_IN) {
198 adns__diag(ads,serv,qu,
199 "ignoring authority RR with wrong class %d (expected IN=%d)",
200 rrclass,DNS_CLASS_IN);
203 if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; }
204 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
207 if (foundsoa || !foundns) {
208 /* Aha ! A NODATA response, good. */
209 adns__query_fail(qu,adns_s_nodata);
213 /* Now what ? No relevant answers, no SOA, and at least some NS's.
214 * Looks like a referral. Just one last chance ... if we came across
215 * a CNAME in this datagram then we should probably do our own CNAME
216 * lookup now in the hope that we won't get a referral again.
218 if (qu->cname_dgram == dgram) { cname_recurse(qu,0); return; }
220 /* Bloody hell, I thought we asked for recursion ? */
222 adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
225 adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
226 adns__query_fail(qu,adns_s_norecurse);
228 adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
229 adns__query_fail(qu,adns_s_serverfaulty);
234 /* Now, we have some RRs which we wanted. */
236 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
237 if (!qu->answer->rrs.untyped) return;
241 for (rri=0; rri<ancount; rri++) {
242 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
243 &rrtype,&rrclass,&rdlength,&rdstart,
245 assert(!st); assert(rrtype != -1);
246 if (rrclass != DNS_CLASS_IN ||
247 rrtype != (qu->typei->type & adns__rrt_typemask) ||
250 assert(qu->answer->nrrs<wantedrrs);
251 st= qu->typei->parse(qu,serv,
252 dgram,dglen, rdstart,rdstart+rdlength,
253 qu->answer->rrs.bytes+qu->answer->nrrs*qu->typei->rrsz);
254 if (st) { adns__query_fail(qu,st); return; }
255 if (rdstart==-1) goto x_truncated;
258 /* This may have generated some child queries ... */
259 if (qu->children.head) {
260 qu->state= query_child;
261 LIST_LINK_TAIL(ads->childw,qu);
265 adns__query_done(qu);
270 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
271 adns__query_fail(qu,adns_s_serverfaulty);
274 if (qu->cname_dgram) { cname_recurse(qu,adns_qf_usevc); return; }
275 adns__reset_cnameonly(qu);
276 qu->flags |= adns_qf_usevc;
277 adns__query_udp(qu,now);