3 * - main handling and parsing routine for received datagrams
7 * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
9 * It is part of adns, which is
10 * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
11 * Copyright (C) 1999 Tony Finch <dot@dotat.at>
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2, or (at your option)
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
23 * You should have received a copy of the GNU General Public License
24 * along with this program; if not, write to the Free Software Foundation,
25 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
32 void adns__procdgram(adns_state ads
, const byte
*dgram
, int dglen
,
33 int serv
, int viatcp
, struct timeval now
) {
34 int cbyte
, rrstart
, wantedrrs
, rri
, foundsoa
, foundns
, cname_here
;
35 int id
, f1
, f2
, qdcount
, ancount
, nscount
, arcount
;
36 int flg_ra
, flg_rd
, flg_tc
, flg_qr
, opcode
;
37 int rrtype
, rrclass
, rdlength
, rdstart
;
38 int anstart
, nsstart
, arstart
;
39 int ownermatched
, l
, nrrs
;
40 unsigned long ttl
, soattl
;
41 const typeinfo
*typei
;
46 byte
*newquery
, *rrsdata
;
49 if (dglen
<DNS_HDRSIZE
) {
50 adns__diag(ads
,serv
,0,"received datagram too short for message header (%d)",dglen
);
61 assert(cbyte
== DNS_HDRSIZE
);
73 adns__diag(ads
,serv
,0,"server sent us a query, not a response");
77 adns__diag(ads
,serv
,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode
);
81 adns__diag(ads
,serv
,0,"server sent reply without quoting our question");
83 } else if (qdcount
>1) {
84 adns__diag(ads
,serv
,0,"server claimed to answer %d questions with one message",
88 for (qu
= viatcp ? ads
->tcpw
.head
: ads
->udpw
.head
; qu
; qu
= nqu
) {
90 if (qu
->id
!= id
) continue;
91 if (dglen
< qu
->query_dglen
) continue;
92 if (memcmp(qu
->query_dgram
+DNS_HDRSIZE
,
94 qu
->query_dglen
-DNS_HDRSIZE
))
97 assert(qu
->state
== query_tcpw
);
99 assert(qu
->state
== query_tosend
);
100 if (!(qu
->udpsent
& (1<<serv
))) continue;
105 if (ads
->iflags
& adns_if_debug
) {
106 adns__vbuf_init(&tempvb
);
107 adns__debug(ads
,serv
,0,"reply not found, id %02x, query owner %s",
108 id
, adns__diag_domain(ads
,serv
,0,&tempvb
,dgram
,dglen
,DNS_HDRSIZE
));
109 adns__vbuf_free(&tempvb
);
113 anstart
= qu
->query_dglen
;
116 if (viatcp
) LIST_UNLINK(ads
->tcpw
,qu
);
117 else LIST_UNLINK(ads
->udpw
,qu
);
118 /* We're definitely going to do something with this query now */
124 case rcode_formaterror
:
125 adns__warn(ads
,serv
,qu
,"server cannot understand our query (Format Error)");
126 adns__query_fail(qu
,adns_s_rcodeformaterror
);
129 adns__query_fail(qu
,adns_s_rcodeservfail
);
132 adns__warn(ads
,serv
,qu
,"server claims not to implement our query");
133 adns__query_fail(qu
,adns_s_rcodenotimplemented
);
136 adns__warn(ads
,serv
,qu
,"server refused our query");
137 adns__query_fail(qu
,adns_s_rcoderefused
);
140 adns__warn(ads
,serv
,qu
,"server gave unknown response code %d",rcode
);
141 adns__query_fail(qu
,adns_s_rcodeunknown
);
145 /* Now, take a look at the answer section, and see if it is complete.
146 * If it has any CNAMEs we stuff them in the answer.
150 for (rri
= 0; rri
<ancount
; rri
++) {
152 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
153 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
,
155 if (st
) { adns__query_fail(qu
,st
); return; }
156 if (rrtype
== -1) goto x_truncated
;
158 if (rrclass
!= DNS_CLASS_IN
) {
159 adns__diag(ads
,serv
,qu
,"ignoring answer RR with wrong class %d (expected IN=%d)",
160 rrclass
,DNS_CLASS_IN
);
164 if (ads
->iflags
& adns_if_debug
) {
165 adns__debug(ads
,serv
,qu
,"ignoring RR with an unexpected owner %s",
166 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
, dgram
,dglen
,rrstart
));
170 if (rrtype
== adns_r_cname
&&
171 (qu
->typei
->type
& adns__rrt_typemask
) != adns_r_cname
) {
172 if (qu
->flags
& adns_qf_cname_forbid
) {
173 adns__query_fail(qu
,adns_s_prohibitedcname
);
175 } else if (qu
->cname_dgram
) { /* Ignore second and subsequent CNAME(s) */
176 adns__debug(ads
,serv
,qu
,"allegedly canonical name %s is actually alias for %s",
178 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
, dgram
,dglen
,rdstart
));
179 adns__query_fail(qu
,adns_s_prohibitedcname
);
181 } else if (wantedrrs
) { /* Ignore CNAME(s) after RR(s). */
182 adns__debug(ads
,serv
,qu
,"ignoring CNAME (to %s) coexisting with RR",
183 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
, dgram
,dglen
,rdstart
));
185 qu
->cname_begin
= rdstart
;
186 qu
->cname_dglen
= dglen
;
187 st
= adns__parse_domain(ads
,serv
,qu
, &qu
->vb
,
188 qu
->flags
& adns_qf_quoteok_cname ? pdf_quoteok
: 0,
189 dgram
,dglen
, &rdstart
,rdstart
+rdlength
);
190 if (!qu
->vb
.used
) goto x_truncated
;
191 if (st
) { adns__query_fail(qu
,st
); return; }
192 l
= strlen(qu
->vb
.buf
)+1;
193 qu
->answer
->cname
= adns__alloc_preserved(qu
,l
);
194 if (!qu
->answer
->cname
) { adns__query_fail(qu
,adns_s_nomemory
); return; }
196 qu
->cname_dgram
= adns__alloc_mine(qu
,dglen
);
197 memcpy(qu
->cname_dgram
,dgram
,dglen
);
199 memcpy(qu
->answer
->cname
,qu
->vb
.buf
,l
);
201 adns__update_expires(qu
,ttl
,now
);
202 /* If we find the answer section truncated after this point we restart
203 * the query at the CNAME; if beforehand then we obviously have to use
204 * TCP. If there is no truncation we can use the whole answer if
205 * it contains the relevant info.
208 } else if (rrtype
== (qu
->typei
->type
& adns__rrt_typemask
)) {
211 adns__debug(ads
,serv
,qu
,"ignoring answer RR with irrelevant type %d",rrtype
);
215 /* We defer handling truncated responses here, in case there was a CNAME
216 * which we could use.
218 if (flg_tc
) goto x_truncated
;
223 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
225 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
226 foundsoa
= 0; soattl
= 0; foundns
= 0;
227 for (rri
= 0; rri
<nscount
; rri
++) {
229 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
230 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
, 0);
231 if (st
) { adns__query_fail(qu
,st
); return; }
232 if (rrtype
==-1) goto x_truncated
;
233 if (rrclass
!= DNS_CLASS_IN
) {
234 adns__diag(ads
,serv
,qu
,
235 "ignoring authority RR with wrong class %d (expected IN=%d)",
236 rrclass
,DNS_CLASS_IN
);
239 if (rrtype
== adns_r_soa_raw
) { foundsoa
= 1; soattl
= ttl
; break; }
240 else if (rrtype
== adns_r_ns_raw
) { foundns
= 1; }
243 if (rcode
== rcode_nxdomain
) {
244 /* We still wanted to look for the SOA so we could find the TTL. */
245 adns__update_expires(qu
,soattl
,now
);
247 if (qu
->flags
& adns_qf_search
) {
248 adns__search_next(ads
,qu
,now
);
250 adns__query_fail(qu
,adns_s_nxdomain
);
255 if (foundsoa
|| !foundns
) {
256 /* Aha ! A NODATA response, good. */
257 adns__update_expires(qu
,soattl
,now
);
258 adns__query_fail(qu
,adns_s_nodata
);
262 /* Now what ? No relevant answers, no SOA, and at least some NS's.
263 * Looks like a referral. Just one last chance ... if we came across
264 * a CNAME in this datagram then we should probably do our own CNAME
265 * lookup now in the hope that we won't get a referral again.
267 if (cname_here
) goto x_restartquery
;
269 /* Bloody hell, I thought we asked for recursion ? */
271 adns__diag(ads
,serv
,qu
,"server thinks we didn't ask for recursive lookup");
274 adns__diag(ads
,serv
,qu
,"server is not willing to do recursive lookups for us");
275 adns__query_fail(qu
,adns_s_norecurse
);
277 adns__diag(ads
,serv
,qu
,"server claims to do recursion, but gave us a referral");
278 adns__query_fail(qu
,adns_s_invalidresponse
);
283 /* Now, we have some RRs which we wanted. */
285 qu
->answer
->rrs
.untyped
= adns__alloc_interim(qu
,qu
->typei
->rrsz
*wantedrrs
);
286 if (!qu
->answer
->rrs
.untyped
) { adns__query_fail(qu
,adns_s_nomemory
); return; }
290 rrsdata
= qu
->answer
->rrs
.bytes
;
297 pai
.nsstart
= nsstart
;
298 pai
.nscount
= nscount
;
299 pai
.arcount
= arcount
;
302 for (rri
=0, nrrs
=0; rri
<ancount
; rri
++) {
303 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
304 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
,
306 assert(!st
); assert(rrtype
!= -1);
307 if (rrclass
!= DNS_CLASS_IN
||
308 rrtype
!= (qu
->typei
->type
& adns__rrt_typemask
) ||
311 adns__update_expires(qu
,ttl
,now
);
312 st
= typei
->parse(&pai
, rdstart
,rdstart
+rdlength
, rrsdata
+nrrs
*typei
->rrsz
);
313 if (st
) { adns__query_fail(qu
,st
); return; }
314 if (rdstart
==-1) goto x_truncated
;
317 assert(nrrs
==wantedrrs
);
318 qu
->answer
->nrrs
= nrrs
;
320 /* This may have generated some child queries ... */
321 if (qu
->children
.head
) {
322 qu
->state
= query_childw
;
323 LIST_LINK_TAIL(ads
->childw
,qu
);
326 adns__query_done(qu
);
332 adns__diag(ads
,serv
,qu
,"server sent datagram which points outside itself");
333 adns__query_fail(qu
,adns_s_invalidresponse
);
336 qu
->flags
|= adns_qf_usevc
;
339 if (qu
->cname_dgram
) {
340 st
= adns__mkquery_frdgram(qu
->ads
,&qu
->vb
,&qu
->id
,
341 qu
->cname_dgram
, qu
->cname_dglen
, qu
->cname_begin
,
342 qu
->typei
->type
, qu
->flags
);
343 if (st
) { adns__query_fail(qu
,st
); return; }
345 newquery
= realloc(qu
->query_dgram
,qu
->vb
.used
);
346 if (!newquery
) { adns__query_fail(qu
,adns_s_nomemory
); return; }
348 qu
->query_dgram
= newquery
;
349 qu
->query_dglen
= qu
->vb
.used
;
350 memcpy(newquery
,qu
->vb
.buf
,qu
->vb
.used
);
353 if (qu
->state
== query_tcpw
) qu
->state
= query_tosend
;
355 adns__reset_preserved(qu
);
356 adns__query_send(qu
,now
);