e576be50 |
1 | /* |
2 | * reply.c |
3 | * - main handling and parsing routine for received datagrams |
4 | */ |
5 | /* |
d942707d |
6 | * This file is |
3d5cde09 |
7 | * Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk> |
d942707d |
8 | * |
9 | * It is part of adns, which is |
3d5cde09 |
10 | * Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk> |
bef232ae |
11 | * Copyright (C) 1999-2000 Tony Finch <dot@dotat.at> |
e576be50 |
12 | * |
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) |
16 | * any later version. |
17 | * |
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. |
22 | * |
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. |
26 | */ |
4353a5c4 |
27 | |
e062dcae |
28 | #include <stdlib.h> |
4353a5c4 |
29 | |
e062dcae |
30 | #include "internal.h" |
b9de380c |
31 | |
98a3f706 |
32 | void adns__procdgram(adns_state ads, const byte *dgram, int dglen, |
ebf4877a |
33 | int serv, int viatcp, struct timeval now) { |
86e7b8d9 |
34 | int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here; |
3955725c |
35 | int id, f1, f2, qdcount, ancount, nscount, arcount; |
36 | int flg_ra, flg_rd, flg_tc, flg_qr, opcode; |
e062dcae |
37 | int rrtype, rrclass, rdlength, rdstart; |
98a3f706 |
38 | int anstart, nsstart, arstart; |
88372443 |
39 | int ownermatched, l, nrrs; |
73dba56e |
40 | unsigned long ttl, soattl; |
e062dcae |
41 | const typeinfo *typei; |
98a3f706 |
42 | adns_query qu, nqu; |
43 | dns_rcode rcode; |
b9de380c |
44 | adns_status st; |
86e7b8d9 |
45 | vbuf tempvb; |
e062dcae |
46 | byte *newquery, *rrsdata; |
1dfe95d8 |
47 | parseinfo pai; |
ec477b9e |
48 | |
98a3f706 |
49 | if (dglen<DNS_HDRSIZE) { |
609133ee |
50 | adns__diag(ads,serv,0,"received datagram" |
51 | " too short for message header (%d)",dglen); |
ec477b9e |
52 | return; |
53 | } |
9557e604 |
54 | cbyte= 0; |
b9de380c |
55 | GET_W(cbyte,id); |
56 | GET_B(cbyte,f1); |
57 | GET_B(cbyte,f2); |
58 | GET_W(cbyte,qdcount); |
59 | GET_W(cbyte,ancount); |
60 | GET_W(cbyte,nscount); |
61 | GET_W(cbyte,arcount); |
98a3f706 |
62 | assert(cbyte == DNS_HDRSIZE); |
ec477b9e |
63 | |
31144a72 |
64 | flg_qr= f1&0x80; |
65 | opcode= (f1&0x78)>>3; |
e062dcae |
66 | flg_tc= f1&0x02; |
31144a72 |
67 | flg_rd= f1&0x01; |
0ba0614a |
68 | flg_ra= f2&0x80; |
86e7b8d9 |
69 | rcode= (f2&0x0f); |
0ba0614a |
70 | |
86e7b8d9 |
71 | cname_here= 0; |
72 | |
9557e604 |
73 | if (!flg_qr) { |
3955725c |
74 | adns__diag(ads,serv,0,"server sent us a query, not a response"); |
ec477b9e |
75 | return; |
76 | } |
31144a72 |
77 | if (opcode) { |
609133ee |
78 | adns__diag(ads,serv,0,"server sent us unknown opcode" |
79 | " %d (wanted 0=QUERY)",opcode); |
ec477b9e |
80 | return; |
81 | } |
16d7d2b5 |
82 | |
83 | qu= 0; |
84 | /* See if we can find the relevant query, or leave qu=0 otherwise ... */ |
85 | |
86 | if (qdcount == 1) { |
87 | for (qu= viatcp ? ads->tcpw.head : ads->udpw.head; qu; qu= nqu) { |
88 | nqu= qu->next; |
89 | if (qu->id != id) continue; |
90 | if (dglen < qu->query_dglen) continue; |
91 | if (memcmp(qu->query_dgram+DNS_HDRSIZE, |
92 | dgram+DNS_HDRSIZE, |
93 | qu->query_dglen-DNS_HDRSIZE)) |
94 | continue; |
95 | if (viatcp) { |
96 | assert(qu->state == query_tcpw); |
97 | } else { |
98 | assert(qu->state == query_tosend); |
99 | if (!(qu->udpsent & (1<<serv))) continue; |
100 | } |
101 | break; |
ebf4877a |
102 | } |
16d7d2b5 |
103 | if (qu) { |
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); |
86e7b8d9 |
107 | } |
ec477b9e |
108 | } |
98a3f706 |
109 | |
16d7d2b5 |
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 |
112 | * any). |
113 | */ |
b9de380c |
114 | switch (rcode) { |
115 | case rcode_noerror: |
116 | case rcode_nxdomain: |
ec477b9e |
117 | break; |
b9de380c |
118 | case rcode_formaterror: |
609133ee |
119 | adns__warn(ads,serv,qu,"server cannot understand our query" |
120 | " (Format Error)"); |
16d7d2b5 |
121 | if (qu) adns__query_fail(qu,adns_s_rcodeformaterror); |
ec477b9e |
122 | return; |
98a3f706 |
123 | case rcode_servfail: |
16d7d2b5 |
124 | if (qu) adns__query_fail(qu,adns_s_rcodeservfail); |
c3ccdc54 |
125 | else adns__debug(ads,serv,qu,"server failure on unidentifiable query"); |
ec477b9e |
126 | return; |
b9de380c |
127 | case rcode_notimp: |
31144a72 |
128 | adns__warn(ads,serv,qu,"server claims not to implement our query"); |
16d7d2b5 |
129 | if (qu) adns__query_fail(qu,adns_s_rcodenotimplemented); |
b9de380c |
130 | return; |
131 | case rcode_refused: |
d00d4b99 |
132 | adns__debug(ads,serv,qu,"server refused our query"); |
16d7d2b5 |
133 | if (qu) adns__query_fail(qu,adns_s_rcoderefused); |
b9de380c |
134 | return; |
135 | default: |
31144a72 |
136 | adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode); |
16d7d2b5 |
137 | if (qu) adns__query_fail(qu,adns_s_rcodeunknown); |
138 | return; |
139 | } |
140 | |
141 | if (!qu) { |
142 | if (!qdcount) { |
143 | adns__diag(ads,serv,0,"server sent reply without quoting our question"); |
144 | } else if (qdcount>1) { |
609133ee |
145 | adns__diag(ads,serv,0,"server claimed to answer %d" |
146 | " questions with one message", qdcount); |
16d7d2b5 |
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", |
609133ee |
150 | id, adns__diag_domain(ads,serv,0,&tempvb, |
151 | dgram,dglen,DNS_HDRSIZE)); |
16d7d2b5 |
152 | adns__vbuf_free(&tempvb); |
153 | } |
b9de380c |
154 | return; |
155 | } |
156 | |
609133ee |
157 | /* We're definitely going to do something with this packet and this |
158 | * query now. */ |
16d7d2b5 |
159 | |
160 | anstart= qu->query_dglen; |
161 | arstart= -1; |
162 | |
b9de380c |
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. |
165 | */ |
166 | wantedrrs= 0; |
86e7b8d9 |
167 | cbyte= anstart; |
b9de380c |
168 | for (rri= 0; rri<ancount; rri++) { |
169 | rrstart= cbyte; |
3955725c |
170 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
171 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
3955725c |
172 | &ownermatched); |
86e7b8d9 |
173 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
174 | if (rrtype == -1) goto x_truncated; |
175 | |
b9de380c |
176 | if (rrclass != DNS_CLASS_IN) { |
609133ee |
177 | adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d" |
178 | " (expected IN=%d)", rrclass,DNS_CLASS_IN); |
b9de380c |
179 | continue; |
180 | } |
0ba0614a |
181 | if (!ownermatched) { |
98a3f706 |
182 | if (ads->iflags & adns_if_debug) { |
31144a72 |
183 | adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s", |
609133ee |
184 | adns__diag_domain(ads,serv,qu, &qu->vb, |
185 | dgram,dglen,rrstart)); |
0ba0614a |
186 | } |
b9de380c |
187 | continue; |
188 | } |
2a6d6736 |
189 | if (rrtype == adns_r_cname && |
31144a72 |
190 | (qu->typei->type & adns__rrt_typemask) != adns_r_cname) { |
4b707d8b |
191 | if (qu->flags & adns_qf_cname_forbid) { |
192 | adns__query_fail(qu,adns_s_prohibitedcname); |
193 | return; |
636b69b1 |
194 | } else if (qu->cname_dgram) { /* Ignore second and subsequent CNAME(s) */ |
609133ee |
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)); |
05db5bce |
199 | adns__query_fail(qu,adns_s_prohibitedcname); |
200 | return; |
636b69b1 |
201 | } else if (wantedrrs) { /* Ignore CNAME(s) after RR(s). */ |
202 | adns__debug(ads,serv,qu,"ignoring CNAME (to %s) coexisting with RR", |
609133ee |
203 | adns__diag_domain(ads,serv,qu, &qu->vb, |
204 | dgram,dglen,rdstart)); |
636b69b1 |
205 | } else { |
31144a72 |
206 | qu->cname_begin= rdstart; |
31144a72 |
207 | qu->cname_dglen= dglen; |
828d89bd |
208 | st= adns__parse_domain(ads,serv,qu, &qu->vb, |
ac015392 |
209 | qu->flags & adns_qf_quotefail_cname |
210 | ? 0 : pdf_quoteok, |
31144a72 |
211 | dgram,dglen, &rdstart,rdstart+rdlength); |
3955725c |
212 | if (!qu->vb.used) goto x_truncated; |
213 | if (st) { adns__query_fail(qu,st); return; } |
214 | l= strlen(qu->vb.buf)+1; |
8b3d55e3 |
215 | qu->answer->cname= adns__alloc_preserved(qu,l); |
609133ee |
216 | if (!qu->answer->cname) { |
217 | adns__query_fail(qu,adns_s_nomemory); |
218 | return; |
219 | } |
e062dcae |
220 | |
221 | qu->cname_dgram= adns__alloc_mine(qu,dglen); |
222 | memcpy(qu->cname_dgram,dgram,dglen); |
223 | |
3955725c |
224 | memcpy(qu->answer->cname,qu->vb.buf,l); |
86e7b8d9 |
225 | cname_here= 1; |
73dba56e |
226 | adns__update_expires(qu,ttl,now); |
31144a72 |
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. |
231 | */ |
31144a72 |
232 | } |
98a3f706 |
233 | } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) { |
b9de380c |
234 | wantedrrs++; |
235 | } else { |
609133ee |
236 | adns__debug(ads,serv,qu,"ignoring answer RR" |
237 | " with irrelevant type %d",rrtype); |
b9de380c |
238 | } |
239 | } |
240 | |
e062dcae |
241 | /* We defer handling truncated responses here, in case there was a CNAME |
242 | * which we could use. |
243 | */ |
244 | if (flg_tc) goto x_truncated; |
245 | |
b9de380c |
246 | nsstart= cbyte; |
247 | |
248 | if (!wantedrrs) { |
609133ee |
249 | /* Oops, NODATA or NXDOMAIN or perhaps a referral |
250 | * (which would be a problem) */ |
b9de380c |
251 | |
609133ee |
252 | /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records |
253 | * in authority section */ |
73dba56e |
254 | foundsoa= 0; soattl= 0; foundns= 0; |
b9de380c |
255 | for (rri= 0; rri<nscount; rri++) { |
0ba0614a |
256 | rrstart= cbyte; |
3955725c |
257 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
258 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0); |
3955725c |
259 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
260 | if (rrtype==-1) goto x_truncated; |
261 | if (rrclass != DNS_CLASS_IN) { |
31144a72 |
262 | adns__diag(ads,serv,qu, |
609133ee |
263 | "ignoring authority RR with wrong class %d" |
264 | " (expected IN=%d)", rrclass,DNS_CLASS_IN); |
0ba0614a |
265 | continue; |
266 | } |
73dba56e |
267 | if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; } |
0ba0614a |
268 | else if (rrtype == adns_r_ns_raw) { foundns= 1; } |
b9de380c |
269 | } |
73dba56e |
270 | |
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); |
660d7d3b |
274 | |
ac015392 |
275 | if (qu->flags & adns_qf_search && !qu->cname_dgram) { |
660d7d3b |
276 | adns__search_next(ads,qu,now); |
277 | } else { |
278 | adns__query_fail(qu,adns_s_nxdomain); |
279 | } |
73dba56e |
280 | return; |
281 | } |
0ba0614a |
282 | |
283 | if (foundsoa || !foundns) { |
284 | /* Aha ! A NODATA response, good. */ |
73dba56e |
285 | adns__update_expires(qu,soattl,now); |
3955725c |
286 | adns__query_fail(qu,adns_s_nodata); |
0ba0614a |
287 | return; |
288 | } |
289 | |
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 |
31144a72 |
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. |
0ba0614a |
294 | */ |
e062dcae |
295 | if (cname_here) goto x_restartquery; |
0ba0614a |
296 | |
297 | /* Bloody hell, I thought we asked for recursion ? */ |
298 | if (!flg_ra) { |
609133ee |
299 | adns__diag(ads,serv,qu,"server is not willing" |
300 | " to do recursive lookups for us"); |
3955725c |
301 | adns__query_fail(qu,adns_s_norecurse); |
31144a72 |
302 | } else { |
d8ae4748 |
303 | if (!flg_rd) |
609133ee |
304 | adns__diag(ads,serv,qu,"server thinks" |
305 | " we didn't ask for recursive lookup"); |
d8ae4748 |
306 | else |
609133ee |
307 | adns__debug(ads,serv,qu,"server claims to do recursion," |
308 | " but gave us a referral"); |
ea1e31e3 |
309 | adns__query_fail(qu,adns_s_invalidresponse); |
0ba0614a |
310 | } |
b9de380c |
311 | return; |
312 | } |
313 | |
0ba0614a |
314 | /* Now, we have some RRs which we wanted. */ |
b9de380c |
315 | |
3955725c |
316 | qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs); |
609133ee |
317 | if (!qu->answer->rrs.untyped) { |
318 | adns__query_fail(qu,adns_s_nomemory); |
319 | return; |
320 | } |
98a3f706 |
321 | |
e062dcae |
322 | typei= qu->typei; |
98a3f706 |
323 | cbyte= anstart; |
e062dcae |
324 | rrsdata= qu->answer->rrs.bytes; |
1dfe95d8 |
325 | |
326 | pai.ads= qu->ads; |
327 | pai.qu= qu; |
328 | pai.serv= serv; |
329 | pai.dgram= dgram; |
330 | pai.dglen= dglen; |
331 | pai.nsstart= nsstart; |
332 | pai.nscount= nscount; |
333 | pai.arcount= arcount; |
7da21070 |
334 | pai.now= now; |
1dfe95d8 |
335 | |
336 | for (rri=0, nrrs=0; rri<ancount; rri++) { |
3955725c |
337 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
338 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
3955725c |
339 | &ownermatched); |
98a3f706 |
340 | assert(!st); assert(rrtype != -1); |
341 | if (rrclass != DNS_CLASS_IN || |
31144a72 |
342 | rrtype != (qu->typei->type & adns__rrt_typemask) || |
343 | !ownermatched) |
98a3f706 |
344 | continue; |
73dba56e |
345 | adns__update_expires(qu,ttl,now); |
1dfe95d8 |
346 | st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz); |
3955725c |
347 | if (st) { adns__query_fail(qu,st); return; } |
31144a72 |
348 | if (rdstart==-1) goto x_truncated; |
e062dcae |
349 | nrrs++; |
98a3f706 |
350 | } |
e062dcae |
351 | assert(nrrs==wantedrrs); |
352 | qu->answer->nrrs= nrrs; |
b9de380c |
353 | |
98a3f706 |
354 | /* This may have generated some child queries ... */ |
355 | if (qu->children.head) { |
f7f83b4a |
356 | qu->state= query_childw; |
98a3f706 |
357 | LIST_LINK_TAIL(ads->childw,qu); |
358 | return; |
b9de380c |
359 | } |
3955725c |
360 | adns__query_done(qu); |
98a3f706 |
361 | return; |
0ba0614a |
362 | |
e576be50 |
363 | x_truncated: |
e062dcae |
364 | |
98a3f706 |
365 | if (!flg_tc) { |
31144a72 |
366 | adns__diag(ads,serv,qu,"server sent datagram which points outside itself"); |
ea1e31e3 |
367 | adns__query_fail(qu,adns_s_invalidresponse); |
98a3f706 |
368 | return; |
369 | } |
98a3f706 |
370 | qu->flags |= adns_qf_usevc; |
e062dcae |
371 | |
372 | x_restartquery: |
e062dcae |
373 | if (qu->cname_dgram) { |
374 | st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id, |
609133ee |
375 | qu->cname_dgram,qu->cname_dglen,qu->cname_begin, |
e062dcae |
376 | qu->typei->type, qu->flags); |
377 | if (st) { adns__query_fail(qu,st); return; } |
378 | |
379 | newquery= realloc(qu->query_dgram,qu->vb.used); |
ea1e31e3 |
380 | if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; } |
e062dcae |
381 | |
382 | qu->query_dgram= newquery; |
383 | qu->query_dglen= qu->vb.used; |
384 | memcpy(newquery,qu->vb.buf,qu->vb.used); |
385 | } |
386 | |
f7f83b4a |
387 | if (qu->state == query_tcpw) qu->state= query_tosend; |
388 | qu->retries= 0; |
8b3d55e3 |
389 | adns__reset_preserved(qu); |
d8c062fa |
390 | adns__query_send(qu,now); |
98a3f706 |
391 | } |