e576be50 |
1 | /* |
2 | * reply.c |
3 | * - main handling and parsing routine for received datagrams |
4 | */ |
5 | /* |
ae8cc977 |
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.) |
e576be50 |
11 | * |
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) |
15 | * any later version. |
16 | * |
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. |
21 | * |
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. |
25 | */ |
4353a5c4 |
26 | |
e062dcae |
27 | #include <stdlib.h> |
4353a5c4 |
28 | |
e062dcae |
29 | #include "internal.h" |
b9de380c |
30 | |
98a3f706 |
31 | void adns__procdgram(adns_state ads, const byte *dgram, int dglen, |
ebf4877a |
32 | int serv, int viatcp, struct timeval now) { |
86e7b8d9 |
33 | int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here; |
3955725c |
34 | int id, f1, f2, qdcount, ancount, nscount, arcount; |
35 | int flg_ra, flg_rd, flg_tc, flg_qr, opcode; |
e062dcae |
36 | int rrtype, rrclass, rdlength, rdstart; |
faa52594 |
37 | int anstart, nsstart; |
88372443 |
38 | int ownermatched, l, nrrs; |
73dba56e |
39 | unsigned long ttl, soattl; |
e062dcae |
40 | const typeinfo *typei; |
98a3f706 |
41 | adns_query qu, nqu; |
42 | dns_rcode rcode; |
b9de380c |
43 | adns_status st; |
86e7b8d9 |
44 | vbuf tempvb; |
e062dcae |
45 | byte *newquery, *rrsdata; |
1dfe95d8 |
46 | parseinfo pai; |
ec477b9e |
47 | |
98a3f706 |
48 | if (dglen<DNS_HDRSIZE) { |
609133ee |
49 | adns__diag(ads,serv,0,"received datagram" |
50 | " too short for message header (%d)",dglen); |
ec477b9e |
51 | return; |
52 | } |
9557e604 |
53 | cbyte= 0; |
b9de380c |
54 | GET_W(cbyte,id); |
55 | GET_B(cbyte,f1); |
56 | GET_B(cbyte,f2); |
57 | GET_W(cbyte,qdcount); |
58 | GET_W(cbyte,ancount); |
59 | GET_W(cbyte,nscount); |
60 | GET_W(cbyte,arcount); |
98a3f706 |
61 | assert(cbyte == DNS_HDRSIZE); |
ec477b9e |
62 | |
31144a72 |
63 | flg_qr= f1&0x80; |
64 | opcode= (f1&0x78)>>3; |
e062dcae |
65 | flg_tc= f1&0x02; |
31144a72 |
66 | flg_rd= f1&0x01; |
0ba0614a |
67 | flg_ra= f2&0x80; |
86e7b8d9 |
68 | rcode= (f2&0x0f); |
0ba0614a |
69 | |
86e7b8d9 |
70 | cname_here= 0; |
71 | |
9557e604 |
72 | if (!flg_qr) { |
3955725c |
73 | adns__diag(ads,serv,0,"server sent us a query, not a response"); |
ec477b9e |
74 | return; |
75 | } |
31144a72 |
76 | if (opcode) { |
609133ee |
77 | adns__diag(ads,serv,0,"server sent us unknown opcode" |
78 | " %d (wanted 0=QUERY)",opcode); |
ec477b9e |
79 | return; |
80 | } |
16d7d2b5 |
81 | |
82 | qu= 0; |
83 | /* See if we can find the relevant query, or leave qu=0 otherwise ... */ |
84 | |
85 | if (qdcount == 1) { |
86 | for (qu= viatcp ? ads->tcpw.head : ads->udpw.head; qu; qu= nqu) { |
87 | nqu= qu->next; |
88 | if (qu->id != id) continue; |
89 | if (dglen < qu->query_dglen) continue; |
90 | if (memcmp(qu->query_dgram+DNS_HDRSIZE, |
91 | dgram+DNS_HDRSIZE, |
92 | qu->query_dglen-DNS_HDRSIZE)) |
93 | continue; |
94 | if (viatcp) { |
95 | assert(qu->state == query_tcpw); |
96 | } else { |
97 | assert(qu->state == query_tosend); |
98 | if (!(qu->udpsent & (1<<serv))) continue; |
99 | } |
100 | break; |
ebf4877a |
101 | } |
16d7d2b5 |
102 | if (qu) { |
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); |
86e7b8d9 |
106 | } |
ec477b9e |
107 | } |
98a3f706 |
108 | |
16d7d2b5 |
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 |
111 | * any). |
112 | */ |
b9de380c |
113 | switch (rcode) { |
114 | case rcode_noerror: |
115 | case rcode_nxdomain: |
ec477b9e |
116 | break; |
b9de380c |
117 | case rcode_formaterror: |
609133ee |
118 | adns__warn(ads,serv,qu,"server cannot understand our query" |
119 | " (Format Error)"); |
16d7d2b5 |
120 | if (qu) adns__query_fail(qu,adns_s_rcodeformaterror); |
ec477b9e |
121 | return; |
98a3f706 |
122 | case rcode_servfail: |
16d7d2b5 |
123 | if (qu) adns__query_fail(qu,adns_s_rcodeservfail); |
c3ccdc54 |
124 | else adns__debug(ads,serv,qu,"server failure on unidentifiable query"); |
ec477b9e |
125 | return; |
b9de380c |
126 | case rcode_notimp: |
31144a72 |
127 | adns__warn(ads,serv,qu,"server claims not to implement our query"); |
16d7d2b5 |
128 | if (qu) adns__query_fail(qu,adns_s_rcodenotimplemented); |
b9de380c |
129 | return; |
130 | case rcode_refused: |
d00d4b99 |
131 | adns__debug(ads,serv,qu,"server refused our query"); |
16d7d2b5 |
132 | if (qu) adns__query_fail(qu,adns_s_rcoderefused); |
b9de380c |
133 | return; |
134 | default: |
31144a72 |
135 | adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode); |
16d7d2b5 |
136 | if (qu) adns__query_fail(qu,adns_s_rcodeunknown); |
137 | return; |
138 | } |
139 | |
140 | if (!qu) { |
141 | if (!qdcount) { |
142 | adns__diag(ads,serv,0,"server sent reply without quoting our question"); |
143 | } else if (qdcount>1) { |
609133ee |
144 | adns__diag(ads,serv,0,"server claimed to answer %d" |
145 | " questions with one message", qdcount); |
16d7d2b5 |
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", |
609133ee |
149 | id, adns__diag_domain(ads,serv,0,&tempvb, |
150 | dgram,dglen,DNS_HDRSIZE)); |
16d7d2b5 |
151 | adns__vbuf_free(&tempvb); |
152 | } |
b9de380c |
153 | return; |
154 | } |
155 | |
609133ee |
156 | /* We're definitely going to do something with this packet and this |
157 | * query now. */ |
16d7d2b5 |
158 | |
159 | anstart= qu->query_dglen; |
16d7d2b5 |
160 | |
b9de380c |
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. |
163 | */ |
164 | wantedrrs= 0; |
86e7b8d9 |
165 | cbyte= anstart; |
b9de380c |
166 | for (rri= 0; rri<ancount; rri++) { |
167 | rrstart= cbyte; |
3955725c |
168 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
169 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
3955725c |
170 | &ownermatched); |
86e7b8d9 |
171 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
172 | if (rrtype == -1) goto x_truncated; |
173 | |
b9de380c |
174 | if (rrclass != DNS_CLASS_IN) { |
609133ee |
175 | adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d" |
176 | " (expected IN=%d)", rrclass,DNS_CLASS_IN); |
b9de380c |
177 | continue; |
178 | } |
0ba0614a |
179 | if (!ownermatched) { |
98a3f706 |
180 | if (ads->iflags & adns_if_debug) { |
31144a72 |
181 | adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s", |
609133ee |
182 | adns__diag_domain(ads,serv,qu, &qu->vb, |
183 | dgram,dglen,rrstart)); |
0ba0614a |
184 | } |
b9de380c |
185 | continue; |
186 | } |
2a6d6736 |
187 | if (rrtype == adns_r_cname && |
2c6eb096 |
188 | (qu->answer->type & adns_rrt_typemask) != adns_r_cname) { |
4b707d8b |
189 | if (qu->flags & adns_qf_cname_forbid) { |
190 | adns__query_fail(qu,adns_s_prohibitedcname); |
191 | return; |
636b69b1 |
192 | } else if (qu->cname_dgram) { /* Ignore second and subsequent CNAME(s) */ |
609133ee |
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)); |
05db5bce |
197 | adns__query_fail(qu,adns_s_prohibitedcname); |
198 | return; |
636b69b1 |
199 | } else if (wantedrrs) { /* Ignore CNAME(s) after RR(s). */ |
200 | adns__debug(ads,serv,qu,"ignoring CNAME (to %s) coexisting with RR", |
609133ee |
201 | adns__diag_domain(ads,serv,qu, &qu->vb, |
202 | dgram,dglen,rdstart)); |
636b69b1 |
203 | } else { |
31144a72 |
204 | qu->cname_begin= rdstart; |
31144a72 |
205 | qu->cname_dglen= dglen; |
828d89bd |
206 | st= adns__parse_domain(ads,serv,qu, &qu->vb, |
ac015392 |
207 | qu->flags & adns_qf_quotefail_cname |
208 | ? 0 : pdf_quoteok, |
31144a72 |
209 | dgram,dglen, &rdstart,rdstart+rdlength); |
3955725c |
210 | if (!qu->vb.used) goto x_truncated; |
211 | if (st) { adns__query_fail(qu,st); return; } |
212 | l= strlen(qu->vb.buf)+1; |
8b3d55e3 |
213 | qu->answer->cname= adns__alloc_preserved(qu,l); |
609133ee |
214 | if (!qu->answer->cname) { |
215 | adns__query_fail(qu,adns_s_nomemory); |
216 | return; |
217 | } |
e062dcae |
218 | |
219 | qu->cname_dgram= adns__alloc_mine(qu,dglen); |
220 | memcpy(qu->cname_dgram,dgram,dglen); |
221 | |
3955725c |
222 | memcpy(qu->answer->cname,qu->vb.buf,l); |
86e7b8d9 |
223 | cname_here= 1; |
73dba56e |
224 | adns__update_expires(qu,ttl,now); |
31144a72 |
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. |
229 | */ |
31144a72 |
230 | } |
2c6eb096 |
231 | } else if (rrtype == (qu->answer->type & adns_rrt_typemask)) { |
b9de380c |
232 | wantedrrs++; |
233 | } else { |
609133ee |
234 | adns__debug(ads,serv,qu,"ignoring answer RR" |
235 | " with irrelevant type %d",rrtype); |
b9de380c |
236 | } |
237 | } |
238 | |
e062dcae |
239 | /* We defer handling truncated responses here, in case there was a CNAME |
240 | * which we could use. |
241 | */ |
242 | if (flg_tc) goto x_truncated; |
243 | |
b9de380c |
244 | nsstart= cbyte; |
245 | |
246 | if (!wantedrrs) { |
609133ee |
247 | /* Oops, NODATA or NXDOMAIN or perhaps a referral |
248 | * (which would be a problem) */ |
b9de380c |
249 | |
609133ee |
250 | /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records |
251 | * in authority section */ |
73dba56e |
252 | foundsoa= 0; soattl= 0; foundns= 0; |
b9de380c |
253 | for (rri= 0; rri<nscount; rri++) { |
0ba0614a |
254 | rrstart= cbyte; |
3955725c |
255 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
256 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0); |
3955725c |
257 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
258 | if (rrtype==-1) goto x_truncated; |
259 | if (rrclass != DNS_CLASS_IN) { |
31144a72 |
260 | adns__diag(ads,serv,qu, |
609133ee |
261 | "ignoring authority RR with wrong class %d" |
262 | " (expected IN=%d)", rrclass,DNS_CLASS_IN); |
0ba0614a |
263 | continue; |
264 | } |
73dba56e |
265 | if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; } |
0ba0614a |
266 | else if (rrtype == adns_r_ns_raw) { foundns= 1; } |
b9de380c |
267 | } |
73dba56e |
268 | |
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); |
660d7d3b |
272 | |
ac015392 |
273 | if (qu->flags & adns_qf_search && !qu->cname_dgram) { |
660d7d3b |
274 | adns__search_next(ads,qu,now); |
275 | } else { |
276 | adns__query_fail(qu,adns_s_nxdomain); |
277 | } |
73dba56e |
278 | return; |
279 | } |
0ba0614a |
280 | |
281 | if (foundsoa || !foundns) { |
282 | /* Aha ! A NODATA response, good. */ |
73dba56e |
283 | adns__update_expires(qu,soattl,now); |
3955725c |
284 | adns__query_fail(qu,adns_s_nodata); |
0ba0614a |
285 | return; |
286 | } |
287 | |
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 |
31144a72 |
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. |
0ba0614a |
292 | */ |
e062dcae |
293 | if (cname_here) goto x_restartquery; |
0ba0614a |
294 | |
295 | /* Bloody hell, I thought we asked for recursion ? */ |
296 | if (!flg_ra) { |
609133ee |
297 | adns__diag(ads,serv,qu,"server is not willing" |
298 | " to do recursive lookups for us"); |
3955725c |
299 | adns__query_fail(qu,adns_s_norecurse); |
31144a72 |
300 | } else { |
d8ae4748 |
301 | if (!flg_rd) |
609133ee |
302 | adns__diag(ads,serv,qu,"server thinks" |
303 | " we didn't ask for recursive lookup"); |
d8ae4748 |
304 | else |
609133ee |
305 | adns__debug(ads,serv,qu,"server claims to do recursion," |
306 | " but gave us a referral"); |
ea1e31e3 |
307 | adns__query_fail(qu,adns_s_invalidresponse); |
0ba0614a |
308 | } |
b9de380c |
309 | return; |
310 | } |
311 | |
0ba0614a |
312 | /* Now, we have some RRs which we wanted. */ |
b9de380c |
313 | |
3955725c |
314 | qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs); |
609133ee |
315 | if (!qu->answer->rrs.untyped) { |
316 | adns__query_fail(qu,adns_s_nomemory); |
317 | return; |
318 | } |
98a3f706 |
319 | |
e062dcae |
320 | typei= qu->typei; |
98a3f706 |
321 | cbyte= anstart; |
e062dcae |
322 | rrsdata= qu->answer->rrs.bytes; |
1dfe95d8 |
323 | |
324 | pai.ads= qu->ads; |
325 | pai.qu= qu; |
326 | pai.serv= serv; |
327 | pai.dgram= dgram; |
328 | pai.dglen= dglen; |
329 | pai.nsstart= nsstart; |
330 | pai.nscount= nscount; |
331 | pai.arcount= arcount; |
7da21070 |
332 | pai.now= now; |
1dfe95d8 |
333 | |
334 | for (rri=0, nrrs=0; rri<ancount; rri++) { |
3955725c |
335 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
336 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
3955725c |
337 | &ownermatched); |
98a3f706 |
338 | assert(!st); assert(rrtype != -1); |
339 | if (rrclass != DNS_CLASS_IN || |
2c6eb096 |
340 | rrtype != (qu->answer->type & adns_rrt_typemask) || |
31144a72 |
341 | !ownermatched) |
98a3f706 |
342 | continue; |
73dba56e |
343 | adns__update_expires(qu,ttl,now); |
1dfe95d8 |
344 | st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz); |
3955725c |
345 | if (st) { adns__query_fail(qu,st); return; } |
31144a72 |
346 | if (rdstart==-1) goto x_truncated; |
e062dcae |
347 | nrrs++; |
98a3f706 |
348 | } |
e062dcae |
349 | assert(nrrs==wantedrrs); |
350 | qu->answer->nrrs= nrrs; |
b9de380c |
351 | |
98a3f706 |
352 | /* This may have generated some child queries ... */ |
353 | if (qu->children.head) { |
f7f83b4a |
354 | qu->state= query_childw; |
98a3f706 |
355 | LIST_LINK_TAIL(ads->childw,qu); |
356 | return; |
b9de380c |
357 | } |
3955725c |
358 | adns__query_done(qu); |
98a3f706 |
359 | return; |
0ba0614a |
360 | |
e576be50 |
361 | x_truncated: |
e062dcae |
362 | |
98a3f706 |
363 | if (!flg_tc) { |
31144a72 |
364 | adns__diag(ads,serv,qu,"server sent datagram which points outside itself"); |
ea1e31e3 |
365 | adns__query_fail(qu,adns_s_invalidresponse); |
98a3f706 |
366 | return; |
367 | } |
98a3f706 |
368 | qu->flags |= adns_qf_usevc; |
e062dcae |
369 | |
370 | x_restartquery: |
e062dcae |
371 | if (qu->cname_dgram) { |
372 | st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id, |
609133ee |
373 | qu->cname_dgram,qu->cname_dglen,qu->cname_begin, |
2c6eb096 |
374 | qu->answer->type, qu->flags); |
e062dcae |
375 | if (st) { adns__query_fail(qu,st); return; } |
376 | |
377 | newquery= realloc(qu->query_dgram,qu->vb.used); |
ea1e31e3 |
378 | if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; } |
e062dcae |
379 | |
380 | qu->query_dgram= newquery; |
381 | qu->query_dglen= qu->vb.used; |
382 | memcpy(newquery,qu->vb.buf,qu->vb.used); |
383 | } |
384 | |
f7f83b4a |
385 | if (qu->state == query_tcpw) qu->state= query_tosend; |
386 | qu->retries= 0; |
8b3d55e3 |
387 | adns__reset_preserved(qu); |
d8c062fa |
388 | adns__query_send(qu,now); |
98a3f706 |
389 | } |