3 * - main handling and parsing routine for received datagrams
6 * This file is part of adns, which is Copyright (C) 1997-1999 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.
27 void adns__procdgram(adns_state ads
, const byte
*dgram
, int dglen
,
28 int serv
, int viatcp
, struct timeval now
) {
29 int cbyte
, rrstart
, wantedrrs
, rri
, foundsoa
, foundns
, cname_here
;
30 int id
, f1
, f2
, qdcount
, ancount
, nscount
, arcount
;
31 int flg_ra
, flg_rd
, flg_tc
, flg_qr
, opcode
;
32 int rrtype
, rrclass
, rdlength
, rdstart
;
33 int anstart
, nsstart
, arstart
;
34 int ownermatched
, l
, nrrs
;
35 unsigned long ttl
, soattl
;
36 const typeinfo
*typei
;
41 byte
*newquery
, *rrsdata
;
44 if (dglen
<DNS_HDRSIZE
) {
45 adns__diag(ads
,serv
,0,"received datagram too short for message header (%d)",dglen
);
56 assert(cbyte
== DNS_HDRSIZE
);
68 adns__diag(ads
,serv
,0,"server sent us a query, not a response");
72 adns__diag(ads
,serv
,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode
);
76 adns__diag(ads
,serv
,0,"server sent reply without quoting our question");
78 } else if (qdcount
>1) {
79 adns__diag(ads
,serv
,0,"server claimed to answer %d questions with one message",
83 for (qu
= ads
->timew
.head
; qu
; qu
= nqu
) {
85 if (qu
->id
!= id
) continue;
86 if (dglen
< qu
->query_dglen
) continue;
87 if (memcmp(qu
->query_dgram
+DNS_HDRSIZE
,
89 qu
->query_dglen
-DNS_HDRSIZE
))
92 if (qu
->state
!= query_tcpsent
) continue;
94 if (qu
->state
!= query_tosend
) continue;
95 if (!(qu
->udpsent
& (1<<serv
))) continue;
100 if (ads
->iflags
& adns_if_debug
) {
101 adns__vbuf_init(&tempvb
);
102 adns__debug(ads
,serv
,0,"reply not found, id %02x, query owner %s",
103 id
, adns__diag_domain(ads
,serv
,0,&tempvb
,dgram
,dglen
,DNS_HDRSIZE
));
104 adns__vbuf_free(&tempvb
);
108 anstart
= qu
->query_dglen
;
111 LIST_UNLINK(ads
->timew
,qu
);
112 /* We're definitely going to do something with this query now */
118 case rcode_formaterror
:
119 adns__warn(ads
,serv
,qu
,"server cannot understand our query (Format Error)");
120 adns__query_fail(qu
,adns_s_rcodeformaterror
);
123 adns__query_fail(qu
,adns_s_rcodeservfail
);
126 adns__warn(ads
,serv
,qu
,"server claims not to implement our query");
127 adns__query_fail(qu
,adns_s_rcodenotimplemented
);
130 adns__warn(ads
,serv
,qu
,"server refused our query");
131 adns__query_fail(qu
,adns_s_rcoderefused
);
134 adns__warn(ads
,serv
,qu
,"server gave unknown response code %d",rcode
);
135 adns__query_fail(qu
,adns_s_rcodeunknown
);
139 /* Now, take a look at the answer section, and see if it is complete.
140 * If it has any CNAMEs we stuff them in the answer.
144 for (rri
= 0; rri
<ancount
; rri
++) {
146 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
147 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
,
149 if (st
) { adns__query_fail(qu
,st
); return; }
150 if (rrtype
== -1) goto x_truncated
;
152 if (rrclass
!= DNS_CLASS_IN
) {
153 adns__diag(ads
,serv
,qu
,"ignoring answer RR with wrong class %d (expected IN=%d)",
154 rrclass
,DNS_CLASS_IN
);
158 if (ads
->iflags
& adns_if_debug
) {
159 adns__debug(ads
,serv
,qu
,"ignoring RR with an unexpected owner %s",
160 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
, dgram
,dglen
,rrstart
));
164 if (rrtype
== adns_r_cname
&&
165 (qu
->typei
->type
& adns__rrt_typemask
) != adns_r_cname
) {
166 if (qu
->flags
& adns_qf_cname_forbid
) {
167 adns__query_fail(qu
,adns_s_prohibitedcname
);
169 } else if (qu
->cname_dgram
) { /* Ignore second and subsequent CNAME(s) */
170 adns__debug(ads
,serv
,qu
,"ignoring duplicate CNAME (%s, as well as %s)",
171 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
, dgram
,dglen
,rdstart
),
173 } else if (wantedrrs
) { /* Ignore CNAME(s) after RR(s). */
174 adns__debug(ads
,serv
,qu
,"ignoring CNAME (to %s) coexisting with RR",
175 adns__diag_domain(ads
,serv
,qu
, &qu
->vb
, dgram
,dglen
,rdstart
));
177 qu
->cname_begin
= rdstart
;
178 qu
->cname_dglen
= dglen
;
179 st
= adns__parse_domain(ads
,serv
,qu
, &qu
->vb
,
180 qu
->flags
& adns_qf_quoteok_cname ? pdf_quoteok
: 0,
181 dgram
,dglen
, &rdstart
,rdstart
+rdlength
);
182 if (!qu
->vb
.used
) goto x_truncated
;
183 if (st
) { adns__query_fail(qu
,st
); return; }
184 l
= strlen(qu
->vb
.buf
)+1;
185 qu
->answer
->cname
= adns__alloc_preserved(qu
,l
);
186 if (!qu
->answer
->cname
) { adns__query_fail(qu
,adns_s_nomemory
); return; }
188 qu
->cname_dgram
= adns__alloc_mine(qu
,dglen
);
189 memcpy(qu
->cname_dgram
,dgram
,dglen
);
191 memcpy(qu
->answer
->cname
,qu
->vb
.buf
,l
);
193 adns__update_expires(qu
,ttl
,now
);
194 /* If we find the answer section truncated after this point we restart
195 * the query at the CNAME; if beforehand then we obviously have to use
196 * TCP. If there is no truncation we can use the whole answer if
197 * it contains the relevant info.
200 } else if (rrtype
== (qu
->typei
->type
& adns__rrt_typemask
)) {
203 adns__debug(ads
,serv
,qu
,"ignoring answer RR with irrelevant type %d",rrtype
);
207 /* We defer handling truncated responses here, in case there was a CNAME
208 * which we could use.
210 if (flg_tc
) goto x_truncated
;
215 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
217 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
218 foundsoa
= 0; soattl
= 0; foundns
= 0;
219 for (rri
= 0; rri
<nscount
; rri
++) {
221 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
222 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
, 0);
223 if (st
) { adns__query_fail(qu
,st
); return; }
224 if (rrtype
==-1) goto x_truncated
;
225 if (rrclass
!= DNS_CLASS_IN
) {
226 adns__diag(ads
,serv
,qu
,
227 "ignoring authority RR with wrong class %d (expected IN=%d)",
228 rrclass
,DNS_CLASS_IN
);
231 if (rrtype
== adns_r_soa_raw
) { foundsoa
= 1; soattl
= ttl
; break; }
232 else if (rrtype
== adns_r_ns_raw
) { foundns
= 1; }
235 if (rcode
== rcode_nxdomain
) {
236 /* We still wanted to look for the SOA so we could find the TTL. */
237 adns__update_expires(qu
,soattl
,now
);
239 if (qu
->flags
& adns_qf_search
) {
240 adns__search_next(ads
,qu
,now
);
242 adns__query_fail(qu
,adns_s_nxdomain
);
247 if (foundsoa
|| !foundns
) {
248 /* Aha ! A NODATA response, good. */
249 adns__update_expires(qu
,soattl
,now
);
250 adns__query_fail(qu
,adns_s_nodata
);
254 /* Now what ? No relevant answers, no SOA, and at least some NS's.
255 * Looks like a referral. Just one last chance ... if we came across
256 * a CNAME in this datagram then we should probably do our own CNAME
257 * lookup now in the hope that we won't get a referral again.
259 if (cname_here
) goto x_restartquery
;
261 /* Bloody hell, I thought we asked for recursion ? */
263 adns__diag(ads
,serv
,qu
,"server thinks we didn't ask for recursive lookup");
266 adns__diag(ads
,serv
,qu
,"server is not willing to do recursive lookups for us");
267 adns__query_fail(qu
,adns_s_norecurse
);
269 adns__diag(ads
,serv
,qu
,"server claims to do recursion, but gave us a referral");
270 adns__query_fail(qu
,adns_s_invalidresponse
);
275 /* Now, we have some RRs which we wanted. */
277 qu
->answer
->rrs
.untyped
= adns__alloc_interim(qu
,qu
->typei
->rrsz
*wantedrrs
);
278 if (!qu
->answer
->rrs
.untyped
) { adns__query_fail(qu
,adns_s_nomemory
); return; }
282 rrsdata
= qu
->answer
->rrs
.bytes
;
289 pai
.nsstart
= nsstart
;
290 pai
.nscount
= nscount
;
291 pai
.arcount
= arcount
;
294 for (rri
=0, nrrs
=0; rri
<ancount
; rri
++) {
295 st
= adns__findrr(qu
,serv
, dgram
,dglen
,&cbyte
,
296 &rrtype
,&rrclass
,&ttl
, &rdlength
,&rdstart
,
298 assert(!st
); assert(rrtype
!= -1);
299 if (rrclass
!= DNS_CLASS_IN
||
300 rrtype
!= (qu
->typei
->type
& adns__rrt_typemask
) ||
303 adns__update_expires(qu
,ttl
,now
);
304 st
= typei
->parse(&pai
, rdstart
,rdstart
+rdlength
, rrsdata
+nrrs
*typei
->rrsz
);
305 if (st
) { adns__query_fail(qu
,st
); return; }
306 if (rdstart
==-1) goto x_truncated
;
309 assert(nrrs
==wantedrrs
);
310 qu
->answer
->nrrs
= nrrs
;
312 /* This may have generated some child queries ... */
313 if (qu
->children
.head
) {
314 qu
->state
= query_child
;
315 LIST_LINK_TAIL(ads
->childw
,qu
);
318 adns__query_done(qu
);
324 adns__diag(ads
,serv
,qu
,"server sent datagram which points outside itself");
325 adns__query_fail(qu
,adns_s_invalidresponse
);
328 qu
->flags
|= adns_qf_usevc
;
331 if (qu
->cname_dgram
) {
332 st
= adns__mkquery_frdgram(qu
->ads
,&qu
->vb
,&qu
->id
,
333 qu
->cname_dgram
, qu
->cname_dglen
, qu
->cname_begin
,
334 qu
->typei
->type
, qu
->flags
);
335 if (st
) { adns__query_fail(qu
,st
); return; }
337 newquery
= realloc(qu
->query_dgram
,qu
->vb
.used
);
338 if (!newquery
) { adns__query_fail(qu
,adns_s_nomemory
); return; }
340 qu
->query_dgram
= newquery
;
341 qu
->query_dglen
= qu
->vb
.used
;
342 memcpy(newquery
,qu
->vb
.buf
,qu
->vb
.used
);
345 if (qu
->state
== query_tcpsent
) qu
->state
= query_tosend
;
346 adns__reset_preserved(qu
);
347 adns__query_send(qu
,now
);