98db6da3 |
1 | /* |
2 | * reply.c |
3 | * - main handling and parsing routine for received datagrams |
4 | */ |
5 | /* |
a79ac5ba |
6 | * This file is |
7 | * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk> |
8 | * |
9 | * It is part of adns, which is |
10 | * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk> |
11 | * Copyright (C) 1999 Tony Finch <dot@dotat.at> |
98db6da3 |
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 | */ |
d05cc330 |
27 | |
f2ad23ee |
28 | #include <stdlib.h> |
d05cc330 |
29 | |
f2ad23ee |
30 | #include "internal.h" |
54ed1d64 |
31 | |
5c596e4d |
32 | void adns__procdgram(adns_state ads, const byte *dgram, int dglen, |
c84b7355 |
33 | int serv, int viatcp, struct timeval now) { |
1e9efa71 |
34 | int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here; |
11c8bf9b |
35 | int id, f1, f2, qdcount, ancount, nscount, arcount; |
36 | int flg_ra, flg_rd, flg_tc, flg_qr, opcode; |
f2ad23ee |
37 | int rrtype, rrclass, rdlength, rdstart; |
5c596e4d |
38 | int anstart, nsstart, arstart; |
f318f883 |
39 | int ownermatched, l, nrrs; |
2c7b101b |
40 | unsigned long ttl, soattl; |
f2ad23ee |
41 | const typeinfo *typei; |
5c596e4d |
42 | adns_query qu, nqu; |
43 | dns_rcode rcode; |
54ed1d64 |
44 | adns_status st; |
1e9efa71 |
45 | vbuf tempvb; |
f2ad23ee |
46 | byte *newquery, *rrsdata; |
26eb6bdc |
47 | parseinfo pai; |
168e26fe |
48 | |
5c596e4d |
49 | if (dglen<DNS_HDRSIZE) { |
11c8bf9b |
50 | adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen); |
168e26fe |
51 | return; |
52 | } |
9a2b67d4 |
53 | cbyte= 0; |
54ed1d64 |
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); |
5c596e4d |
61 | assert(cbyte == DNS_HDRSIZE); |
168e26fe |
62 | |
7f702335 |
63 | flg_qr= f1&0x80; |
64 | opcode= (f1&0x78)>>3; |
f2ad23ee |
65 | flg_tc= f1&0x02; |
7f702335 |
66 | flg_rd= f1&0x01; |
8312a1c2 |
67 | flg_ra= f2&0x80; |
1e9efa71 |
68 | rcode= (f2&0x0f); |
8312a1c2 |
69 | |
1e9efa71 |
70 | cname_here= 0; |
71 | |
9a2b67d4 |
72 | if (!flg_qr) { |
11c8bf9b |
73 | adns__diag(ads,serv,0,"server sent us a query, not a response"); |
168e26fe |
74 | return; |
75 | } |
7f702335 |
76 | if (opcode) { |
11c8bf9b |
77 | adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode); |
168e26fe |
78 | return; |
79 | } |
47eed012 |
80 | |
81 | qu= 0; |
82 | /* See if we can find the relevant query, or leave qu=0 otherwise ... */ |
83 | |
84 | if (qdcount == 1) { |
85 | for (qu= viatcp ? ads->tcpw.head : ads->udpw.head; qu; qu= nqu) { |
86 | nqu= qu->next; |
87 | if (qu->id != id) continue; |
88 | if (dglen < qu->query_dglen) continue; |
89 | if (memcmp(qu->query_dgram+DNS_HDRSIZE, |
90 | dgram+DNS_HDRSIZE, |
91 | qu->query_dglen-DNS_HDRSIZE)) |
92 | continue; |
93 | if (viatcp) { |
94 | assert(qu->state == query_tcpw); |
95 | } else { |
96 | assert(qu->state == query_tosend); |
97 | if (!(qu->udpsent & (1<<serv))) continue; |
98 | } |
99 | break; |
c84b7355 |
100 | } |
47eed012 |
101 | if (qu) { |
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); |
1e9efa71 |
105 | } |
168e26fe |
106 | } |
5c596e4d |
107 | |
47eed012 |
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 |
110 | * any). |
111 | */ |
54ed1d64 |
112 | switch (rcode) { |
113 | case rcode_noerror: |
114 | case rcode_nxdomain: |
168e26fe |
115 | break; |
54ed1d64 |
116 | case rcode_formaterror: |
7f702335 |
117 | adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)"); |
47eed012 |
118 | if (qu) adns__query_fail(qu,adns_s_rcodeformaterror); |
168e26fe |
119 | return; |
5c596e4d |
120 | case rcode_servfail: |
47eed012 |
121 | if (qu) adns__query_fail(qu,adns_s_rcodeservfail); |
122 | else adns__warn(ads,serv,qu,"server failure on unidentifiable query"); |
168e26fe |
123 | return; |
54ed1d64 |
124 | case rcode_notimp: |
7f702335 |
125 | adns__warn(ads,serv,qu,"server claims not to implement our query"); |
47eed012 |
126 | if (qu) adns__query_fail(qu,adns_s_rcodenotimplemented); |
54ed1d64 |
127 | return; |
128 | case rcode_refused: |
7f702335 |
129 | adns__warn(ads,serv,qu,"server refused our query"); |
47eed012 |
130 | if (qu) adns__query_fail(qu,adns_s_rcoderefused); |
54ed1d64 |
131 | return; |
132 | default: |
7f702335 |
133 | adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode); |
47eed012 |
134 | if (qu) adns__query_fail(qu,adns_s_rcodeunknown); |
135 | return; |
136 | } |
137 | |
138 | if (!qu) { |
139 | if (!qdcount) { |
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", |
143 | qdcount); |
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); |
149 | } |
54ed1d64 |
150 | return; |
151 | } |
152 | |
47eed012 |
153 | /* We're definitely going to do something with this packet and this query now. */ |
154 | |
155 | anstart= qu->query_dglen; |
156 | arstart= -1; |
157 | |
54ed1d64 |
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. |
160 | */ |
161 | wantedrrs= 0; |
1e9efa71 |
162 | cbyte= anstart; |
54ed1d64 |
163 | for (rri= 0; rri<ancount; rri++) { |
164 | rrstart= cbyte; |
11c8bf9b |
165 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
2c7b101b |
166 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
11c8bf9b |
167 | &ownermatched); |
1e9efa71 |
168 | if (st) { adns__query_fail(qu,st); return; } |
8312a1c2 |
169 | if (rrtype == -1) goto x_truncated; |
170 | |
54ed1d64 |
171 | if (rrclass != DNS_CLASS_IN) { |
7f702335 |
172 | adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)", |
54ed1d64 |
173 | rrclass,DNS_CLASS_IN); |
174 | continue; |
175 | } |
8312a1c2 |
176 | if (!ownermatched) { |
5c596e4d |
177 | if (ads->iflags & adns_if_debug) { |
7f702335 |
178 | adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s", |
cd363ffd |
179 | adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rrstart)); |
8312a1c2 |
180 | } |
54ed1d64 |
181 | continue; |
182 | } |
940c3875 |
183 | if (rrtype == adns_r_cname && |
7f702335 |
184 | (qu->typei->type & adns__rrt_typemask) != adns_r_cname) { |
59fbb06a |
185 | if (qu->flags & adns_qf_cname_forbid) { |
186 | adns__query_fail(qu,adns_s_prohibitedcname); |
187 | return; |
125de2a9 |
188 | } else if (qu->cname_dgram) { /* Ignore second and subsequent CNAME(s) */ |
9dbde8ca |
189 | adns__debug(ads,serv,qu,"allegedly canonical name %s is actually alias for %s", |
190 | qu->answer->cname, |
191 | adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart)); |
192 | adns__query_fail(qu,adns_s_prohibitedcname); |
193 | return; |
125de2a9 |
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)); |
197 | } else { |
7f702335 |
198 | qu->cname_begin= rdstart; |
7f702335 |
199 | qu->cname_dglen= dglen; |
cd363ffd |
200 | st= adns__parse_domain(ads,serv,qu, &qu->vb, |
201 | qu->flags & adns_qf_quoteok_cname ? pdf_quoteok : 0, |
7f702335 |
202 | dgram,dglen, &rdstart,rdstart+rdlength); |
11c8bf9b |
203 | if (!qu->vb.used) goto x_truncated; |
204 | if (st) { adns__query_fail(qu,st); return; } |
205 | l= strlen(qu->vb.buf)+1; |
1be24aef |
206 | qu->answer->cname= adns__alloc_preserved(qu,l); |
9b86645c |
207 | if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; } |
f2ad23ee |
208 | |
209 | qu->cname_dgram= adns__alloc_mine(qu,dglen); |
210 | memcpy(qu->cname_dgram,dgram,dglen); |
211 | |
11c8bf9b |
212 | memcpy(qu->answer->cname,qu->vb.buf,l); |
1e9efa71 |
213 | cname_here= 1; |
2c7b101b |
214 | adns__update_expires(qu,ttl,now); |
7f702335 |
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. |
219 | */ |
7f702335 |
220 | } |
5c596e4d |
221 | } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) { |
54ed1d64 |
222 | wantedrrs++; |
223 | } else { |
7f702335 |
224 | adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype); |
54ed1d64 |
225 | } |
226 | } |
227 | |
f2ad23ee |
228 | /* We defer handling truncated responses here, in case there was a CNAME |
229 | * which we could use. |
230 | */ |
231 | if (flg_tc) goto x_truncated; |
232 | |
54ed1d64 |
233 | nsstart= cbyte; |
234 | |
235 | if (!wantedrrs) { |
236 | /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */ |
54ed1d64 |
237 | |
238 | /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */ |
2c7b101b |
239 | foundsoa= 0; soattl= 0; foundns= 0; |
54ed1d64 |
240 | for (rri= 0; rri<nscount; rri++) { |
8312a1c2 |
241 | rrstart= cbyte; |
11c8bf9b |
242 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
2c7b101b |
243 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0); |
11c8bf9b |
244 | if (st) { adns__query_fail(qu,st); return; } |
8312a1c2 |
245 | if (rrtype==-1) goto x_truncated; |
246 | if (rrclass != DNS_CLASS_IN) { |
7f702335 |
247 | adns__diag(ads,serv,qu, |
248 | "ignoring authority RR with wrong class %d (expected IN=%d)", |
8312a1c2 |
249 | rrclass,DNS_CLASS_IN); |
250 | continue; |
251 | } |
2c7b101b |
252 | if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; } |
8312a1c2 |
253 | else if (rrtype == adns_r_ns_raw) { foundns= 1; } |
54ed1d64 |
254 | } |
2c7b101b |
255 | |
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); |
7e6a84a1 |
259 | |
260 | if (qu->flags & adns_qf_search) { |
261 | adns__search_next(ads,qu,now); |
262 | } else { |
263 | adns__query_fail(qu,adns_s_nxdomain); |
264 | } |
2c7b101b |
265 | return; |
266 | } |
8312a1c2 |
267 | |
268 | if (foundsoa || !foundns) { |
269 | /* Aha ! A NODATA response, good. */ |
2c7b101b |
270 | adns__update_expires(qu,soattl,now); |
11c8bf9b |
271 | adns__query_fail(qu,adns_s_nodata); |
8312a1c2 |
272 | return; |
273 | } |
274 | |
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 |
7f702335 |
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. |
8312a1c2 |
279 | */ |
f2ad23ee |
280 | if (cname_here) goto x_restartquery; |
8312a1c2 |
281 | |
282 | /* Bloody hell, I thought we asked for recursion ? */ |
7f702335 |
283 | if (flg_rd) { |
284 | adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup"); |
285 | } |
8312a1c2 |
286 | if (!flg_ra) { |
7f702335 |
287 | adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us"); |
11c8bf9b |
288 | adns__query_fail(qu,adns_s_norecurse); |
7f702335 |
289 | } else { |
290 | adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral"); |
9b86645c |
291 | adns__query_fail(qu,adns_s_invalidresponse); |
8312a1c2 |
292 | } |
54ed1d64 |
293 | return; |
294 | } |
295 | |
8312a1c2 |
296 | /* Now, we have some RRs which we wanted. */ |
54ed1d64 |
297 | |
11c8bf9b |
298 | qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs); |
9b86645c |
299 | if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nomemory); return; } |
5c596e4d |
300 | |
f2ad23ee |
301 | typei= qu->typei; |
5c596e4d |
302 | cbyte= anstart; |
f2ad23ee |
303 | rrsdata= qu->answer->rrs.bytes; |
26eb6bdc |
304 | |
305 | pai.ads= qu->ads; |
306 | pai.qu= qu; |
307 | pai.serv= serv; |
308 | pai.dgram= dgram; |
309 | pai.dglen= dglen; |
310 | pai.nsstart= nsstart; |
311 | pai.nscount= nscount; |
312 | pai.arcount= arcount; |
ba1ddf08 |
313 | pai.now= now; |
26eb6bdc |
314 | |
315 | for (rri=0, nrrs=0; rri<ancount; rri++) { |
11c8bf9b |
316 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
2c7b101b |
317 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
11c8bf9b |
318 | &ownermatched); |
5c596e4d |
319 | assert(!st); assert(rrtype != -1); |
320 | if (rrclass != DNS_CLASS_IN || |
7f702335 |
321 | rrtype != (qu->typei->type & adns__rrt_typemask) || |
322 | !ownermatched) |
5c596e4d |
323 | continue; |
2c7b101b |
324 | adns__update_expires(qu,ttl,now); |
26eb6bdc |
325 | st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz); |
11c8bf9b |
326 | if (st) { adns__query_fail(qu,st); return; } |
7f702335 |
327 | if (rdstart==-1) goto x_truncated; |
f2ad23ee |
328 | nrrs++; |
5c596e4d |
329 | } |
f2ad23ee |
330 | assert(nrrs==wantedrrs); |
331 | qu->answer->nrrs= nrrs; |
54ed1d64 |
332 | |
5c596e4d |
333 | /* This may have generated some child queries ... */ |
334 | if (qu->children.head) { |
d0a057ac |
335 | qu->state= query_childw; |
5c596e4d |
336 | LIST_LINK_TAIL(ads->childw,qu); |
337 | return; |
54ed1d64 |
338 | } |
11c8bf9b |
339 | adns__query_done(qu); |
5c596e4d |
340 | return; |
8312a1c2 |
341 | |
98db6da3 |
342 | x_truncated: |
f2ad23ee |
343 | |
5c596e4d |
344 | if (!flg_tc) { |
7f702335 |
345 | adns__diag(ads,serv,qu,"server sent datagram which points outside itself"); |
9b86645c |
346 | adns__query_fail(qu,adns_s_invalidresponse); |
5c596e4d |
347 | return; |
348 | } |
5c596e4d |
349 | qu->flags |= adns_qf_usevc; |
f2ad23ee |
350 | |
351 | x_restartquery: |
f2ad23ee |
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; } |
357 | |
358 | newquery= realloc(qu->query_dgram,qu->vb.used); |
9b86645c |
359 | if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; } |
f2ad23ee |
360 | |
361 | qu->query_dgram= newquery; |
362 | qu->query_dglen= qu->vb.used; |
363 | memcpy(newquery,qu->vb.buf,qu->vb.used); |
364 | } |
365 | |
d0a057ac |
366 | if (qu->state == query_tcpw) qu->state= query_tosend; |
367 | qu->retries= 0; |
1be24aef |
368 | adns__reset_preserved(qu); |
24d52b13 |
369 | adns__query_send(qu,now); |
5c596e4d |
370 | } |