3 * - main handling and parsing routine for received datagrams
7 * Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
9 * It is part of adns, which is
10 * Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
11 * Copyright (C) 1999-2000 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"
51 " too short for message header (%d)",dglen
);
62 assert(cbyte
== DNS_HDRSIZE
);
74 adns__diag(ads
,serv
,0,"server sent us a query, not a response");
78 adns__diag(ads
,serv
,0,"server sent us unknown opcode"
79 " %d (wanted 0=QUERY)",opcode
);
84 /* See if we can find the relevant query, or leave qu=0 otherwise ... */
87 for (qu
= viatcp ? ads
->tcpw
.head
: ads
->udpw
.head
; qu
; qu
= nqu
) {
89 if (qu
->id
!= id
) continue;
90 if (dglen
< qu
->query_dglen
) continue;
91 if (memcmp(qu
->query_dgram
+DNS_HDRSIZE
,
93 qu
->query_dglen
-DNS_HDRSIZE
))
96 assert(qu
->state
== query_tcpw
);
98 assert(qu
->state
== query_tosend
);
99 if (!(qu
->udpsent
& (1<<serv
))) continue;
104 /* We're definitely going to do something with this query now */
105 if (viatcp
) LIST_UNLINK(ads
->tcpw
,qu
);
106 else LIST_UNLINK(ads
->udpw
,qu
);
110 /* If we're going to ignore the packet, we return as soon as we have
111 * failed the query (if any) and printed the warning message (if
118 case rcode_formaterror
:
119 adns__warn(ads
,serv
,qu
,"server cannot understand our query"
121 if (qu
) adns__query_fail(qu
,adns_s_rcodeformaterror
);
124 if (qu
) adns__query_fail(qu
,adns_s_rcodeservfail
);
125 else adns__debug(ads
,serv
,qu
,"server failure on unidentifiable query");
128 adns__warn(ads
,serv
,qu
,"server claims not to implement our query");
129 if (qu
) adns__query_fail(qu
,adns_s_rcodenotimplemented
);
132 adns__debug(ads
,serv
,qu
,"server refused our query");
133 if (qu
) adns__query_fail(qu
,adns_s_rcoderefused
);
136 adns__warn(ads
,serv
,qu
,"server gave unknown response code %d",rcode
);
137 if (qu
) adns__query_fail(qu
,adns_s_rcodeunknown
);
143 adns__diag(ads
,serv
,0,"server sent reply without quoting our question");
144 } else if (qdcount
>1) {
145 adns__diag(ads
,serv
,0,"server claimed to answer %d"
146 " questions with one message", qdcount
);
147 } else if (ads
->iflags
& adns_if_debug
) {
148 adns__vbuf_init(&tempvb
);
149 adns__debug(ads
,serv
,0,"reply not found, id %02x, query owner %s",
150 id
, adns__diag_domain(ads
,serv
,0,&tempvb
,
151 dgram
,dglen
,DNS_HDRSIZE
));
152 adns__vbuf_free(&tempvb
);
157 /* We're definitely going to do something with this packet and this
160 anstart
= qu
->query_dglen
;
163 /* Now, take a look at the answer section, and see if it is complete.
164 * If it has any CNAMEs we stuff them in the answer.
168 for (rri
= 0; rri
<ancount
; rri
++) {
170 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
171 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
,
173 if (st
) { adns__query_fail(qu
,st
); return; }
174 if (rrtype
== -1) goto x_truncated
;
176 if (rrclass
!= DNS_CLASS_IN
) {
177 adns__diag(ads
,serv
,qu
,"ignoring answer RR with wrong class %d"
178 " (expected IN=%d)", rrclass
,DNS_CLASS_IN
);
182 if (ads
->iflags
& adns_if_debug
) {
183 adns__debug(ads
,serv
,qu
,"ignoring RR with an unexpected owner %s",
184 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
,
185 dgram
,dglen
,rrstart
));
189 if (rrtype
== adns_r_cname
&&
190 (qu
->typei
->type
& adns__rrt_typemask
) != adns_r_cname
) {
191 if (qu
->flags
& adns_qf_cname_forbid
) {
192 adns__query_fail(qu
,adns_s_prohibitedcname
);
194 } else if (qu
->cname_dgram
) { /* Ignore second and subsequent CNAME(s) */
195 adns__debug(ads
,serv
,qu
,"allegedly canonical name %s"
196 " is actually alias for %s", qu
->answer
->cname
,
197 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
,
198 dgram
,dglen
,rdstart
));
199 adns__query_fail(qu
,adns_s_prohibitedcname
);
201 } else if (wantedrrs
) { /* Ignore CNAME(s) after RR(s). */
202 adns__debug(ads
,serv
,qu
,"ignoring CNAME (to %s) coexisting with RR",
203 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
,
204 dgram
,dglen
,rdstart
));
206 qu
->cname_begin
= rdstart
;
207 qu
->cname_dglen
= dglen
;
208 st
= adns__parse_domain(ads
,serv
,qu
, &qu
->vb
,
209 qu
->flags
& adns_qf_quotefail_cname
211 dgram
,dglen
, &rdstart
,rdstart
+rdlength
);
212 if (!qu
->vb
.used
) goto x_truncated
;
213 if (st
) { adns__query_fail(qu
,st
); return; }
214 l
= strlen(qu
->vb
.buf
)+1;
215 qu
->answer
->cname
= adns__alloc_preserved(qu
,l
);
216 if (!qu
->answer
->cname
) {
217 adns__query_fail(qu
,adns_s_nomemory
);
221 qu
->cname_dgram
= adns__alloc_mine(qu
,dglen
);
222 memcpy(qu
->cname_dgram
,dgram
,dglen
);
224 memcpy(qu
->answer
->cname
,qu
->vb
.buf
,l
);
226 adns__update_expires(qu
,ttl
,now
);
227 /* If we find the answer section truncated after this point we restart
228 * the query at the CNAME; if beforehand then we obviously have to use
229 * TCP. If there is no truncation we can use the whole answer if
230 * it contains the relevant info.
233 } else if (rrtype
== (qu
->typei
->type
& adns__rrt_typemask
)) {
236 adns__debug(ads
,serv
,qu
,"ignoring answer RR"
237 " with irrelevant type %d",rrtype
);
241 /* We defer handling truncated responses here, in case there was a CNAME
242 * which we could use.
244 if (flg_tc
) goto x_truncated
;
249 /* Oops, NODATA or NXDOMAIN or perhaps a referral
250 * (which would be a problem) */
252 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records
253 * in authority section */
254 foundsoa
= 0; soattl
= 0; foundns
= 0;
255 for (rri
= 0; rri
<nscount
; rri
++) {
257 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
258 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
, 0);
259 if (st
) { adns__query_fail(qu
,st
); return; }
260 if (rrtype
==-1) goto x_truncated
;
261 if (rrclass
!= DNS_CLASS_IN
) {
262 adns__diag(ads
,serv
,qu
,
263 "ignoring authority RR with wrong class %d"
264 " (expected IN=%d)", rrclass
,DNS_CLASS_IN
);
267 if (rrtype
== adns_r_soa_raw
) { foundsoa
= 1; soattl
= ttl
; break; }
268 else if (rrtype
== adns_r_ns_raw
) { foundns
= 1; }
271 if (rcode
== rcode_nxdomain
) {
272 /* We still wanted to look for the SOA so we could find the TTL. */
273 adns__update_expires(qu
,soattl
,now
);
275 if (qu
->flags
& adns_qf_search
&& !qu
->cname_dgram
) {
276 adns__search_next(ads
,qu
,now
);
278 adns__query_fail(qu
,adns_s_nxdomain
);
283 if (foundsoa
|| !foundns
) {
284 /* Aha ! A NODATA response, good. */
285 adns__update_expires(qu
,soattl
,now
);
286 adns__query_fail(qu
,adns_s_nodata
);
290 /* Now what ? No relevant answers, no SOA, and at least some NS's.
291 * Looks like a referral. Just one last chance ... if we came across
292 * a CNAME in this datagram then we should probably do our own CNAME
293 * lookup now in the hope that we won't get a referral again.
295 if (cname_here
) goto x_restartquery
;
297 /* Bloody hell, I thought we asked for recursion ? */
299 adns__diag(ads
,serv
,qu
,"server is not willing"
300 " to do recursive lookups for us");
301 adns__query_fail(qu
,adns_s_norecurse
);
304 adns__diag(ads
,serv
,qu
,"server thinks"
305 " we didn't ask for recursive lookup");
307 adns__debug(ads
,serv
,qu
,"server claims to do recursion,"
308 " but gave us a referral");
309 adns__query_fail(qu
,adns_s_invalidresponse
);
314 /* Now, we have some RRs which we wanted. */
316 qu
->answer
->rrs
.untyped
= adns__alloc_interim(qu
,qu
->typei
->rrsz
*wantedrrs
);
317 if (!qu
->answer
->rrs
.untyped
) {
318 adns__query_fail(qu
,adns_s_nomemory
);
324 rrsdata
= qu
->answer
->rrs
.bytes
;
331 pai
.nsstart
= nsstart
;
332 pai
.nscount
= nscount
;
333 pai
.arcount
= arcount
;
336 for (rri
=0, nrrs
=0; rri
<ancount
; rri
++) {
337 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
338 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
,
340 assert(!st
); assert(rrtype
!= -1);
341 if (rrclass
!= DNS_CLASS_IN
||
342 rrtype
!= (qu
->typei
->type
& adns__rrt_typemask
) ||
345 adns__update_expires(qu
,ttl
,now
);
346 st
= typei
->parse(&pai
, rdstart
,rdstart
+rdlength
, rrsdata
+nrrs
*typei
->rrsz
);
347 if (st
) { adns__query_fail(qu
,st
); return; }
348 if (rdstart
==-1) goto x_truncated
;
351 assert(nrrs
==wantedrrs
);
352 qu
->answer
->nrrs
= nrrs
;
354 /* This may have generated some child queries ... */
355 if (qu
->children
.head
) {
356 qu
->state
= query_childw
;
357 LIST_LINK_TAIL(ads
->childw
,qu
);
360 adns__query_done(qu
);
366 adns__diag(ads
,serv
,qu
,"server sent datagram which points outside itself");
367 adns__query_fail(qu
,adns_s_invalidresponse
);
370 qu
->flags
|= adns_qf_usevc
;
373 if (qu
->cname_dgram
) {
374 st
= adns__mkquery_frdgram(qu
->ads
,&qu
->vb
,&qu
->id
,
375 qu
->cname_dgram
,qu
->cname_dglen
,qu
->cname_begin
,
376 qu
->typei
->type
, qu
->flags
);
377 if (st
) { adns__query_fail(qu
,st
); return; }
379 newquery
= realloc(qu
->query_dgram
,qu
->vb
.used
);
380 if (!newquery
) { adns__query_fail(qu
,adns_s_nomemory
); return; }
382 qu
->query_dgram
= newquery
;
383 qu
->query_dglen
= qu
->vb
.used
;
384 memcpy(newquery
,qu
->vb
.buf
,qu
->vb
.used
);
387 if (qu
->state
== query_tcpw
) qu
->state
= query_tosend
;
389 adns__reset_preserved(qu
);
390 adns__query_send(qu
,now
);