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 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
);
82 /* See if we can find the relevant query, or leave qu=0 otherwise ... */
85 for (qu
= viatcp ? ads
->tcpw
.head
: ads
->udpw
.head
; qu
; qu
= nqu
) {
87 if (qu
->id
!= id
) continue;
88 if (dglen
< qu
->query_dglen
) continue;
89 if (memcmp(qu
->query_dgram
+DNS_HDRSIZE
,
91 qu
->query_dglen
-DNS_HDRSIZE
))
94 assert(qu
->state
== query_tcpw
);
96 assert(qu
->state
== query_tosend
);
97 if (!(qu
->udpsent
& (1<<serv
))) continue;
102 /* We're definitely going to do something with this query now */
103 if (viatcp
) LIST_UNLINK(ads
->tcpw
,qu
);
104 else LIST_UNLINK(ads
->udpw
,qu
);
108 /* If we're going to ignore the packet, we return as soon as we have
109 * failed the query (if any) and printed the warning message (if
116 case rcode_formaterror
:
117 adns__warn(ads
,serv
,qu
,"server cannot understand our query (Format Error)");
118 if (qu
) adns__query_fail(qu
,adns_s_rcodeformaterror
);
121 if (qu
) adns__query_fail(qu
,adns_s_rcodeservfail
);
122 else adns__debug(ads
,serv
,qu
,"server failure on unidentifiable query");
125 adns__warn(ads
,serv
,qu
,"server claims not to implement our query");
126 if (qu
) adns__query_fail(qu
,adns_s_rcodenotimplemented
);
129 adns__warn(ads
,serv
,qu
,"server refused our query");
130 if (qu
) adns__query_fail(qu
,adns_s_rcoderefused
);
133 adns__warn(ads
,serv
,qu
,"server gave unknown response code %d",rcode
);
134 if (qu
) adns__query_fail(qu
,adns_s_rcodeunknown
);
140 adns__diag(ads
,serv
,0,"server sent reply without quoting our question");
141 } else if (qdcount
>1) {
142 adns__diag(ads
,serv
,0,"server claimed to answer %d questions with one message",
144 } else if (ads
->iflags
& adns_if_debug
) {
145 adns__vbuf_init(&tempvb
);
146 adns__debug(ads
,serv
,0,"reply not found, id %02x, query owner %s",
147 id
, adns__diag_domain(ads
,serv
,0,&tempvb
,dgram
,dglen
,DNS_HDRSIZE
));
148 adns__vbuf_free(&tempvb
);
153 /* We're definitely going to do something with this packet and this query now. */
155 anstart
= qu
->query_dglen
;
158 /* Now, take a look at the answer section, and see if it is complete.
159 * If it has any CNAMEs we stuff them in the answer.
163 for (rri
= 0; rri
<ancount
; rri
++) {
165 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
166 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
,
168 if (st
) { adns__query_fail(qu
,st
); return; }
169 if (rrtype
== -1) goto x_truncated
;
171 if (rrclass
!= DNS_CLASS_IN
) {
172 adns__diag(ads
,serv
,qu
,"ignoring answer RR with wrong class %d (expected IN=%d)",
173 rrclass
,DNS_CLASS_IN
);
177 if (ads
->iflags
& adns_if_debug
) {
178 adns__debug(ads
,serv
,qu
,"ignoring RR with an unexpected owner %s",
179 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
, dgram
,dglen
,rrstart
));
183 if (rrtype
== adns_r_cname
&&
184 (qu
->typei
->type
& adns__rrt_typemask
) != adns_r_cname
) {
185 if (qu
->flags
& adns_qf_cname_forbid
) {
186 adns__query_fail(qu
,adns_s_prohibitedcname
);
188 } else if (qu
->cname_dgram
) { /* Ignore second and subsequent CNAME(s) */
189 adns__debug(ads
,serv
,qu
,"allegedly canonical name %s is actually alias for %s",
191 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
, dgram
,dglen
,rdstart
));
192 adns__query_fail(qu
,adns_s_prohibitedcname
);
194 } else if (wantedrrs
) { /* Ignore CNAME(s) after RR(s). */
195 adns__debug(ads
,serv
,qu
,"ignoring CNAME (to %s) coexisting with RR",
196 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
, dgram
,dglen
,rdstart
));
198 qu
->cname_begin
= rdstart
;
199 qu
->cname_dglen
= dglen
;
200 st
= adns__parse_domain(ads
,serv
,qu
, &qu
->vb
,
201 qu
->flags
& adns_qf_quotefail_cname ?
0 : pdf_quoteok
,
202 dgram
,dglen
, &rdstart
,rdstart
+rdlength
);
203 if (!qu
->vb
.used
) goto x_truncated
;
204 if (st
) { adns__query_fail(qu
,st
); return; }
205 l
= strlen(qu
->vb
.buf
)+1;
206 qu
->answer
->cname
= adns__alloc_preserved(qu
,l
);
207 if (!qu
->answer
->cname
) { adns__query_fail(qu
,adns_s_nomemory
); return; }
209 qu
->cname_dgram
= adns__alloc_mine(qu
,dglen
);
210 memcpy(qu
->cname_dgram
,dgram
,dglen
);
212 memcpy(qu
->answer
->cname
,qu
->vb
.buf
,l
);
214 adns__update_expires(qu
,ttl
,now
);
215 /* If we find the answer section truncated after this point we restart
216 * the query at the CNAME; if beforehand then we obviously have to use
217 * TCP. If there is no truncation we can use the whole answer if
218 * it contains the relevant info.
221 } else if (rrtype
== (qu
->typei
->type
& adns__rrt_typemask
)) {
224 adns__debug(ads
,serv
,qu
,"ignoring answer RR with irrelevant type %d",rrtype
);
228 /* We defer handling truncated responses here, in case there was a CNAME
229 * which we could use.
231 if (flg_tc
) goto x_truncated
;
236 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
238 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
239 foundsoa
= 0; soattl
= 0; foundns
= 0;
240 for (rri
= 0; rri
<nscount
; rri
++) {
242 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
243 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
, 0);
244 if (st
) { adns__query_fail(qu
,st
); return; }
245 if (rrtype
==-1) goto x_truncated
;
246 if (rrclass
!= DNS_CLASS_IN
) {
247 adns__diag(ads
,serv
,qu
,
248 "ignoring authority RR with wrong class %d (expected IN=%d)",
249 rrclass
,DNS_CLASS_IN
);
252 if (rrtype
== adns_r_soa_raw
) { foundsoa
= 1; soattl
= ttl
; break; }
253 else if (rrtype
== adns_r_ns_raw
) { foundns
= 1; }
256 if (rcode
== rcode_nxdomain
) {
257 /* We still wanted to look for the SOA so we could find the TTL. */
258 adns__update_expires(qu
,soattl
,now
);
260 if (qu
->flags
& adns_qf_search
) {
261 adns__search_next(ads
,qu
,now
);
263 adns__query_fail(qu
,adns_s_nxdomain
);
268 if (foundsoa
|| !foundns
) {
269 /* Aha ! A NODATA response, good. */
270 adns__update_expires(qu
,soattl
,now
);
271 adns__query_fail(qu
,adns_s_nodata
);
275 /* Now what ? No relevant answers, no SOA, and at least some NS's.
276 * Looks like a referral. Just one last chance ... if we came across
277 * a CNAME in this datagram then we should probably do our own CNAME
278 * lookup now in the hope that we won't get a referral again.
280 if (cname_here
) goto x_restartquery
;
282 /* Bloody hell, I thought we asked for recursion ? */
284 adns__diag(ads
,serv
,qu
,"server is not willing to do recursive lookups for us");
285 adns__query_fail(qu
,adns_s_norecurse
);
288 adns__diag(ads
,serv
,qu
,"server thinks we didn't ask for recursive lookup");
290 adns__diag(ads
,serv
,qu
,"server claims to do recursion, but gave us a referral");
291 adns__query_fail(qu
,adns_s_invalidresponse
);
296 /* Now, we have some RRs which we wanted. */
298 qu
->answer
->rrs
.untyped
= adns__alloc_interim(qu
,qu
->typei
->rrsz
*wantedrrs
);
299 if (!qu
->answer
->rrs
.untyped
) { adns__query_fail(qu
,adns_s_nomemory
); return; }
303 rrsdata
= qu
->answer
->rrs
.bytes
;
310 pai
.nsstart
= nsstart
;
311 pai
.nscount
= nscount
;
312 pai
.arcount
= arcount
;
315 for (rri
=0, nrrs
=0; rri
<ancount
; rri
++) {
316 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
317 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
,
319 assert(!st
); assert(rrtype
!= -1);
320 if (rrclass
!= DNS_CLASS_IN
||
321 rrtype
!= (qu
->typei
->type
& adns__rrt_typemask
) ||
324 adns__update_expires(qu
,ttl
,now
);
325 st
= typei
->parse(&pai
, rdstart
,rdstart
+rdlength
, rrsdata
+nrrs
*typei
->rrsz
);
326 if (st
) { adns__query_fail(qu
,st
); return; }
327 if (rdstart
==-1) goto x_truncated
;
330 assert(nrrs
==wantedrrs
);
331 qu
->answer
->nrrs
= nrrs
;
333 /* This may have generated some child queries ... */
334 if (qu
->children
.head
) {
335 qu
->state
= query_childw
;
336 LIST_LINK_TAIL(ads
->childw
,qu
);
339 adns__query_done(qu
);
345 adns__diag(ads
,serv
,qu
,"server sent datagram which points outside itself");
346 adns__query_fail(qu
,adns_s_invalidresponse
);
349 qu
->flags
|= adns_qf_usevc
;
352 if (qu
->cname_dgram
) {
353 st
= adns__mkquery_frdgram(qu
->ads
,&qu
->vb
,&qu
->id
,
354 qu
->cname_dgram
, qu
->cname_dglen
, qu
->cname_begin
,
355 qu
->typei
->type
, qu
->flags
);
356 if (st
) { adns__query_fail(qu
,st
); return; }
358 newquery
= realloc(qu
->query_dgram
,qu
->vb
.used
);
359 if (!newquery
) { adns__query_fail(qu
,adns_s_nomemory
); return; }
361 qu
->query_dgram
= newquery
;
362 qu
->query_dglen
= qu
->vb
.used
;
363 memcpy(newquery
,qu
->vb
.buf
,qu
->vb
.used
);
366 if (qu
->state
== query_tcpw
) qu
->state
= query_tosend
;
368 adns__reset_preserved(qu
);
369 adns__query_send(qu
,now
);