3 * - main handling and parsing routine for received datagrams
6 * This file is part of adns, which is
7 * Copyright (C) 1997-2000,2003,2006 Ian Jackson
8 * Copyright (C) 1999-2000,2003,2006 Tony Finch
9 * Copyright (C) 1991 Massachusetts Institute of Technology
10 * (See the file INSTALL for full details.)
12 * This program is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License as published by
14 * the Free Software Foundation; either version 2, or (at your option)
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software Foundation,
24 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
31 void adns__procdgram(adns_state ads
, const byte
*dgram
, int dglen
,
32 int serv
, int viatcp
, struct timeval now
) {
33 int cbyte
, rrstart
, wantedrrs
, rri
, foundsoa
, foundns
, cname_here
;
34 int id
, f1
, f2
, qdcount
, ancount
, nscount
, arcount
;
35 int flg_ra
, flg_rd
, flg_tc
, flg_qr
, opcode
;
36 int rrtype
, rrclass
, rdlength
, rdstart
;
38 int ownermatched
, l
, nrrs
;
39 unsigned long ttl
, soattl
;
40 const typeinfo
*typei
;
45 byte
*newquery
, *rrsdata
;
48 if (dglen
<DNS_HDRSIZE
) {
49 adns__diag(ads
,serv
,0,"received datagram"
50 " 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"
78 " %d (wanted 0=QUERY)",opcode
);
83 /* See if we can find the relevant query, or leave qu=0 otherwise ... */
86 for (qu
= viatcp ? ads
->tcpw
.head
: ads
->udpw
.head
; qu
; qu
= nqu
) {
88 if (qu
->id
!= id
) continue;
89 if (dglen
< qu
->query_dglen
) continue;
90 if (memcmp(qu
->query_dgram
+DNS_HDRSIZE
,
92 qu
->query_dglen
-DNS_HDRSIZE
))
95 assert(qu
->state
== query_tcpw
);
97 assert(qu
->state
== query_tosend
);
98 if (!(qu
->udpsent
& (1<<serv
))) continue;
103 /* We're definitely going to do something with this query now */
104 if (viatcp
) LIST_UNLINK(ads
->tcpw
,qu
);
105 else LIST_UNLINK(ads
->udpw
,qu
);
109 /* If we're going to ignore the packet, we return as soon as we have
110 * failed the query (if any) and printed the warning message (if
117 case rcode_formaterror
:
118 adns__warn(ads
,serv
,qu
,"server cannot understand our query"
120 if (qu
) adns__query_fail(qu
,adns_s_rcodeformaterror
);
123 if (qu
) adns__query_fail(qu
,adns_s_rcodeservfail
);
124 else adns__debug(ads
,serv
,qu
,"server failure on unidentifiable query");
127 adns__warn(ads
,serv
,qu
,"server claims not to implement our query");
128 if (qu
) adns__query_fail(qu
,adns_s_rcodenotimplemented
);
131 adns__debug(ads
,serv
,qu
,"server refused our query");
132 if (qu
) adns__query_fail(qu
,adns_s_rcoderefused
);
135 adns__warn(ads
,serv
,qu
,"server gave unknown response code %d",rcode
);
136 if (qu
) adns__query_fail(qu
,adns_s_rcodeunknown
);
142 adns__diag(ads
,serv
,0,"server sent reply without quoting our question");
143 } else if (qdcount
>1) {
144 adns__diag(ads
,serv
,0,"server claimed to answer %d"
145 " questions with one message", qdcount
);
146 } else if (ads
->iflags
& adns_if_debug
) {
147 adns__vbuf_init(&tempvb
);
148 adns__debug(ads
,serv
,0,"reply not found, id %02x, query owner %s",
149 id
, adns__diag_domain(ads
,serv
,0,&tempvb
,
150 dgram
,dglen
,DNS_HDRSIZE
));
151 adns__vbuf_free(&tempvb
);
156 /* We're definitely going to do something with this packet and this
159 anstart
= qu
->query_dglen
;
161 /* Now, take a look at the answer section, and see if it is complete.
162 * If it has any CNAMEs we stuff them in the answer.
166 for (rri
= 0; rri
<ancount
; rri
++) {
168 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
169 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
,
171 if (st
) { adns__query_fail(qu
,st
); return; }
172 if (rrtype
== -1) goto x_truncated
;
174 if (rrclass
!= DNS_CLASS_IN
) {
175 adns__diag(ads
,serv
,qu
,"ignoring answer RR with wrong class %d"
176 " (expected IN=%d)", rrclass
,DNS_CLASS_IN
);
180 if (ads
->iflags
& adns_if_debug
) {
181 adns__debug(ads
,serv
,qu
,"ignoring RR with an unexpected owner %s",
182 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
,
183 dgram
,dglen
,rrstart
));
187 if (rrtype
== adns_r_cname
&&
188 (qu
->answer
->type
& adns_rrt_typemask
) != adns_r_cname
) {
189 if (qu
->flags
& adns_qf_cname_forbid
) {
190 adns__query_fail(qu
,adns_s_prohibitedcname
);
192 } else if (qu
->cname_dgram
) { /* Ignore second and subsequent CNAME(s) */
193 adns__debug(ads
,serv
,qu
,"allegedly canonical name %s"
194 " is actually alias for %s", qu
->answer
->cname
,
195 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
,
196 dgram
,dglen
,rdstart
));
197 adns__query_fail(qu
,adns_s_prohibitedcname
);
199 } else if (wantedrrs
) { /* Ignore CNAME(s) after RR(s). */
200 adns__debug(ads
,serv
,qu
,"ignoring CNAME (to %s) coexisting with RR",
201 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
,
202 dgram
,dglen
,rdstart
));
204 qu
->cname_begin
= rdstart
;
205 qu
->cname_dglen
= dglen
;
206 st
= adns__parse_domain(ads
,serv
,qu
, &qu
->vb
,
207 qu
->flags
& adns_qf_quotefail_cname
209 dgram
,dglen
, &rdstart
,rdstart
+rdlength
);
210 if (!qu
->vb
.used
) goto x_truncated
;
211 if (st
) { adns__query_fail(qu
,st
); return; }
212 l
= strlen(qu
->vb
.buf
)+1;
213 qu
->answer
->cname
= adns__alloc_preserved(qu
,l
);
214 if (!qu
->answer
->cname
) {
215 adns__query_fail(qu
,adns_s_nomemory
);
219 qu
->cname_dgram
= adns__alloc_mine(qu
,dglen
);
220 memcpy(qu
->cname_dgram
,dgram
,dglen
);
222 memcpy(qu
->answer
->cname
,qu
->vb
.buf
,l
);
224 adns__update_expires(qu
,ttl
,now
);
225 /* If we find the answer section truncated after this point we restart
226 * the query at the CNAME; if beforehand then we obviously have to use
227 * TCP. If there is no truncation we can use the whole answer if
228 * it contains the relevant info.
231 } else if (rrtype
== (qu
->answer
->type
& adns_rrt_typemask
)) {
234 adns__debug(ads
,serv
,qu
,"ignoring answer RR"
235 " with irrelevant type %d",rrtype
);
239 /* We defer handling truncated responses here, in case there was a CNAME
240 * which we could use.
242 if (flg_tc
) goto x_truncated
;
247 /* Oops, NODATA or NXDOMAIN or perhaps a referral
248 * (which would be a problem) */
250 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records
251 * in authority section */
252 foundsoa
= 0; soattl
= 0; foundns
= 0;
253 for (rri
= 0; rri
<nscount
; rri
++) {
255 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
256 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
, 0);
257 if (st
) { adns__query_fail(qu
,st
); return; }
258 if (rrtype
==-1) goto x_truncated
;
259 if (rrclass
!= DNS_CLASS_IN
) {
260 adns__diag(ads
,serv
,qu
,
261 "ignoring authority RR with wrong class %d"
262 " (expected IN=%d)", rrclass
,DNS_CLASS_IN
);
265 if (rrtype
== adns_r_soa_raw
) { foundsoa
= 1; soattl
= ttl
; break; }
266 else if (rrtype
== adns_r_ns_raw
) { foundns
= 1; }
269 if (rcode
== rcode_nxdomain
) {
270 /* We still wanted to look for the SOA so we could find the TTL. */
271 adns__update_expires(qu
,soattl
,now
);
273 if (qu
->flags
& adns_qf_search
&& !qu
->cname_dgram
) {
274 adns__search_next(ads
,qu
,now
);
276 adns__query_fail(qu
,adns_s_nxdomain
);
281 if (foundsoa
|| !foundns
) {
282 /* Aha ! A NODATA response, good. */
283 adns__update_expires(qu
,soattl
,now
);
284 adns__query_fail(qu
,adns_s_nodata
);
288 /* Now what ? No relevant answers, no SOA, and at least some NS's.
289 * Looks like a referral. Just one last chance ... if we came across
290 * a CNAME in this datagram then we should probably do our own CNAME
291 * lookup now in the hope that we won't get a referral again.
293 if (cname_here
) goto x_restartquery
;
295 /* Bloody hell, I thought we asked for recursion ? */
297 adns__diag(ads
,serv
,qu
,"server is not willing"
298 " to do recursive lookups for us");
299 adns__query_fail(qu
,adns_s_norecurse
);
302 adns__diag(ads
,serv
,qu
,"server thinks"
303 " we didn't ask for recursive lookup");
305 adns__debug(ads
,serv
,qu
,"server claims to do recursion,"
306 " but gave us a referral");
307 adns__query_fail(qu
,adns_s_invalidresponse
);
312 /* Now, we have some RRs which we wanted. */
314 qu
->answer
->rrs
.untyped
= adns__alloc_interim(qu
,qu
->typei
->rrsz
*wantedrrs
);
315 if (!qu
->answer
->rrs
.untyped
) {
316 adns__query_fail(qu
,adns_s_nomemory
);
322 rrsdata
= qu
->answer
->rrs
.bytes
;
329 pai
.nsstart
= nsstart
;
330 pai
.nscount
= nscount
;
331 pai
.arcount
= arcount
;
334 for (rri
=0, nrrs
=0; rri
<ancount
; rri
++) {
335 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
336 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
,
338 assert(!st
); assert(rrtype
!= -1);
339 if (rrclass
!= DNS_CLASS_IN
||
340 rrtype
!= (qu
->answer
->type
& adns_rrt_typemask
) ||
343 adns__update_expires(qu
,ttl
,now
);
344 st
= typei
->parse(&pai
, rdstart
,rdstart
+rdlength
, rrsdata
+nrrs
*typei
->rrsz
);
345 if (st
) { adns__query_fail(qu
,st
); return; }
346 if (rdstart
==-1) goto x_truncated
;
349 assert(nrrs
==wantedrrs
);
350 qu
->answer
->nrrs
= nrrs
;
352 /* This may have generated some child queries ... */
353 if (qu
->children
.head
) {
354 qu
->state
= query_childw
;
355 LIST_LINK_TAIL(ads
->childw
,qu
);
358 adns__query_done(qu
);
364 adns__diag(ads
,serv
,qu
,"server sent datagram which points outside itself");
365 adns__query_fail(qu
,adns_s_invalidresponse
);
368 qu
->flags
|= adns_qf_usevc
;
371 if (qu
->cname_dgram
) {
372 st
= adns__mkquery_frdgram(qu
->ads
,&qu
->vb
,&qu
->id
,
373 qu
->cname_dgram
,qu
->cname_dglen
,qu
->cname_begin
,
374 qu
->answer
->type
, qu
->flags
);
375 if (st
) { adns__query_fail(qu
,st
); return; }
377 newquery
= realloc(qu
->query_dgram
,qu
->vb
.used
);
378 if (!newquery
) { adns__query_fail(qu
,adns_s_nomemory
); return; }
380 qu
->query_dgram
= newquery
;
381 qu
->query_dglen
= qu
->vb
.used
;
382 memcpy(newquery
,qu
->vb
.buf
,qu
->vb
.used
);
385 if (qu
->state
== query_tcpw
) qu
->state
= query_tosend
;
387 adns__reset_preserved(qu
);
388 adns__query_send(qu
,now
);