98db6da3 |
1 | /* |
2 | * reply.c |
3 | * - main handling and parsing routine for received datagrams |
4 | */ |
5 | /* |
3ff64957 |
6 | * This file is part of adns, which is Copyright (C) 1997-1999 Ian Jackson |
98db6da3 |
7 | * |
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) |
11 | * any later version. |
12 | * |
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. |
17 | * |
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. |
21 | */ |
d05cc330 |
22 | |
f2ad23ee |
23 | #include <stdlib.h> |
24 | #include <string.h> |
d05cc330 |
25 | |
f2ad23ee |
26 | #include "internal.h" |
54ed1d64 |
27 | |
5c596e4d |
28 | void adns__procdgram(adns_state ads, const byte *dgram, int dglen, |
29 | int serv, struct timeval now) { |
1e9efa71 |
30 | int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here; |
11c8bf9b |
31 | int id, f1, f2, qdcount, ancount, nscount, arcount; |
32 | int flg_ra, flg_rd, flg_tc, flg_qr, opcode; |
f2ad23ee |
33 | int rrtype, rrclass, rdlength, rdstart; |
5c596e4d |
34 | int anstart, nsstart, arstart; |
f318f883 |
35 | int ownermatched, l, nrrs; |
2c7b101b |
36 | unsigned long ttl, soattl; |
f2ad23ee |
37 | const typeinfo *typei; |
5c596e4d |
38 | adns_query qu, nqu; |
39 | dns_rcode rcode; |
54ed1d64 |
40 | adns_status st; |
1e9efa71 |
41 | vbuf tempvb; |
f2ad23ee |
42 | byte *newquery, *rrsdata; |
26eb6bdc |
43 | parseinfo pai; |
168e26fe |
44 | |
5c596e4d |
45 | if (dglen<DNS_HDRSIZE) { |
11c8bf9b |
46 | adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen); |
168e26fe |
47 | return; |
48 | } |
9a2b67d4 |
49 | cbyte= 0; |
54ed1d64 |
50 | GET_W(cbyte,id); |
51 | GET_B(cbyte,f1); |
52 | GET_B(cbyte,f2); |
53 | GET_W(cbyte,qdcount); |
54 | GET_W(cbyte,ancount); |
55 | GET_W(cbyte,nscount); |
56 | GET_W(cbyte,arcount); |
5c596e4d |
57 | assert(cbyte == DNS_HDRSIZE); |
168e26fe |
58 | |
7f702335 |
59 | flg_qr= f1&0x80; |
60 | opcode= (f1&0x78)>>3; |
f2ad23ee |
61 | flg_tc= f1&0x02; |
7f702335 |
62 | flg_rd= f1&0x01; |
8312a1c2 |
63 | flg_ra= f2&0x80; |
1e9efa71 |
64 | rcode= (f2&0x0f); |
8312a1c2 |
65 | |
1e9efa71 |
66 | cname_here= 0; |
67 | |
9a2b67d4 |
68 | if (!flg_qr) { |
11c8bf9b |
69 | adns__diag(ads,serv,0,"server sent us a query, not a response"); |
168e26fe |
70 | return; |
71 | } |
7f702335 |
72 | if (opcode) { |
11c8bf9b |
73 | adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode); |
168e26fe |
74 | return; |
75 | } |
76 | if (!qdcount) { |
11c8bf9b |
77 | adns__diag(ads,serv,0,"server sent reply without quoting our question"); |
168e26fe |
78 | return; |
79 | } else if (qdcount>1) { |
11c8bf9b |
80 | adns__diag(ads,serv,0,"server claimed to answer %d questions with one message", |
168e26fe |
81 | qdcount); |
82 | return; |
83 | } |
5c596e4d |
84 | for (qu= ads->timew.head; qu; qu= nqu) { |
168e26fe |
85 | nqu= qu->next; |
86 | if (qu->id != id) continue; |
11c8bf9b |
87 | if (dglen < qu->query_dglen) continue; |
88 | if (memcmp(qu->query_dgram+DNS_HDRSIZE, |
89 | dgram+DNS_HDRSIZE, |
90 | qu->query_dglen-DNS_HDRSIZE)) |
54ed1d64 |
91 | continue; |
168e26fe |
92 | break; |
93 | } |
94 | if (!qu) { |
1e9efa71 |
95 | if (ads->iflags & adns_if_debug) { |
96 | adns__vbuf_init(&tempvb); |
97 | adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s", |
cd363ffd |
98 | id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE)); |
1e9efa71 |
99 | adns__vbuf_free(&tempvb); |
100 | } |
168e26fe |
101 | return; |
102 | } |
1e9efa71 |
103 | anstart= qu->query_dglen; |
f318f883 |
104 | arstart= -1; |
5c596e4d |
105 | |
106 | LIST_UNLINK(ads->timew,qu); |
107 | /* We're definitely going to do something with this query now */ |
108 | |
54ed1d64 |
109 | switch (rcode) { |
110 | case rcode_noerror: |
111 | case rcode_nxdomain: |
168e26fe |
112 | break; |
54ed1d64 |
113 | case rcode_formaterror: |
7f702335 |
114 | adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)"); |
9b86645c |
115 | adns__query_fail(qu,adns_s_rcodeformaterror); |
168e26fe |
116 | return; |
5c596e4d |
117 | case rcode_servfail: |
9b86645c |
118 | adns__query_fail(qu,adns_s_rcodeservfail); |
168e26fe |
119 | return; |
54ed1d64 |
120 | case rcode_notimp: |
7f702335 |
121 | adns__warn(ads,serv,qu,"server claims not to implement our query"); |
9b86645c |
122 | adns__query_fail(qu,adns_s_rcodenotimplemented); |
54ed1d64 |
123 | return; |
124 | case rcode_refused: |
7f702335 |
125 | adns__warn(ads,serv,qu,"server refused our query"); |
9b86645c |
126 | adns__query_fail(qu,adns_s_rcoderefused); |
54ed1d64 |
127 | return; |
128 | default: |
7f702335 |
129 | adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode); |
9b86645c |
130 | adns__query_fail(qu,adns_s_rcodeunknown); |
54ed1d64 |
131 | return; |
132 | } |
133 | |
134 | /* Now, take a look at the answer section, and see if it is complete. |
135 | * If it has any CNAMEs we stuff them in the answer. |
136 | */ |
137 | wantedrrs= 0; |
1e9efa71 |
138 | cbyte= anstart; |
54ed1d64 |
139 | for (rri= 0; rri<ancount; rri++) { |
140 | rrstart= cbyte; |
11c8bf9b |
141 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
2c7b101b |
142 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
11c8bf9b |
143 | &ownermatched); |
1e9efa71 |
144 | if (st) { adns__query_fail(qu,st); return; } |
8312a1c2 |
145 | if (rrtype == -1) goto x_truncated; |
146 | |
54ed1d64 |
147 | if (rrclass != DNS_CLASS_IN) { |
7f702335 |
148 | adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)", |
54ed1d64 |
149 | rrclass,DNS_CLASS_IN); |
150 | continue; |
151 | } |
8312a1c2 |
152 | if (!ownermatched) { |
5c596e4d |
153 | if (ads->iflags & adns_if_debug) { |
7f702335 |
154 | adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s", |
cd363ffd |
155 | adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rrstart)); |
8312a1c2 |
156 | } |
54ed1d64 |
157 | continue; |
158 | } |
940c3875 |
159 | if (rrtype == adns_r_cname && |
7f702335 |
160 | (qu->typei->type & adns__rrt_typemask) != adns_r_cname) { |
59fbb06a |
161 | if (qu->flags & adns_qf_cname_forbid) { |
162 | adns__query_fail(qu,adns_s_prohibitedcname); |
163 | return; |
164 | } else if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */ |
7f702335 |
165 | qu->cname_begin= rdstart; |
7f702335 |
166 | qu->cname_dglen= dglen; |
cd363ffd |
167 | st= adns__parse_domain(ads,serv,qu, &qu->vb, |
168 | qu->flags & adns_qf_quoteok_cname ? pdf_quoteok : 0, |
7f702335 |
169 | dgram,dglen, &rdstart,rdstart+rdlength); |
11c8bf9b |
170 | if (!qu->vb.used) goto x_truncated; |
171 | if (st) { adns__query_fail(qu,st); return; } |
172 | l= strlen(qu->vb.buf)+1; |
173 | qu->answer->cname= adns__alloc_interim(qu,l); |
9b86645c |
174 | if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; } |
f2ad23ee |
175 | |
176 | qu->cname_dgram= adns__alloc_mine(qu,dglen); |
177 | memcpy(qu->cname_dgram,dgram,dglen); |
178 | |
11c8bf9b |
179 | memcpy(qu->answer->cname,qu->vb.buf,l); |
1e9efa71 |
180 | cname_here= 1; |
2c7b101b |
181 | adns__update_expires(qu,ttl,now); |
7f702335 |
182 | /* If we find the answer section truncated after this point we restart |
183 | * the query at the CNAME; if beforehand then we obviously have to use |
184 | * TCP. If there is no truncation we can use the whole answer if |
185 | * it contains the relevant info. |
186 | */ |
187 | } else { |
188 | adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)", |
cd363ffd |
189 | adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart), |
11c8bf9b |
190 | qu->answer->cname); |
7f702335 |
191 | } |
5c596e4d |
192 | } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) { |
54ed1d64 |
193 | wantedrrs++; |
194 | } else { |
7f702335 |
195 | adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype); |
54ed1d64 |
196 | } |
197 | } |
198 | |
f2ad23ee |
199 | /* We defer handling truncated responses here, in case there was a CNAME |
200 | * which we could use. |
201 | */ |
202 | if (flg_tc) goto x_truncated; |
203 | |
54ed1d64 |
204 | nsstart= cbyte; |
205 | |
206 | if (!wantedrrs) { |
207 | /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */ |
54ed1d64 |
208 | |
209 | /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */ |
2c7b101b |
210 | foundsoa= 0; soattl= 0; foundns= 0; |
54ed1d64 |
211 | for (rri= 0; rri<nscount; rri++) { |
8312a1c2 |
212 | rrstart= cbyte; |
11c8bf9b |
213 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
2c7b101b |
214 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0); |
11c8bf9b |
215 | if (st) { adns__query_fail(qu,st); return; } |
8312a1c2 |
216 | if (rrtype==-1) goto x_truncated; |
217 | if (rrclass != DNS_CLASS_IN) { |
7f702335 |
218 | adns__diag(ads,serv,qu, |
219 | "ignoring authority RR with wrong class %d (expected IN=%d)", |
8312a1c2 |
220 | rrclass,DNS_CLASS_IN); |
221 | continue; |
222 | } |
2c7b101b |
223 | if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; } |
8312a1c2 |
224 | else if (rrtype == adns_r_ns_raw) { foundns= 1; } |
54ed1d64 |
225 | } |
2c7b101b |
226 | |
227 | if (rcode == rcode_nxdomain) { |
228 | /* We still wanted to look for the SOA so we could find the TTL. */ |
229 | adns__update_expires(qu,soattl,now); |
7e6a84a1 |
230 | |
231 | if (qu->flags & adns_qf_search) { |
232 | adns__search_next(ads,qu,now); |
233 | } else { |
234 | adns__query_fail(qu,adns_s_nxdomain); |
235 | } |
2c7b101b |
236 | return; |
237 | } |
8312a1c2 |
238 | |
239 | if (foundsoa || !foundns) { |
240 | /* Aha ! A NODATA response, good. */ |
2c7b101b |
241 | adns__update_expires(qu,soattl,now); |
11c8bf9b |
242 | adns__query_fail(qu,adns_s_nodata); |
8312a1c2 |
243 | return; |
244 | } |
245 | |
246 | /* Now what ? No relevant answers, no SOA, and at least some NS's. |
247 | * Looks like a referral. Just one last chance ... if we came across |
7f702335 |
248 | * a CNAME in this datagram then we should probably do our own CNAME |
249 | * lookup now in the hope that we won't get a referral again. |
8312a1c2 |
250 | */ |
f2ad23ee |
251 | if (cname_here) goto x_restartquery; |
8312a1c2 |
252 | |
253 | /* Bloody hell, I thought we asked for recursion ? */ |
7f702335 |
254 | if (flg_rd) { |
255 | adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup"); |
256 | } |
8312a1c2 |
257 | if (!flg_ra) { |
7f702335 |
258 | adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us"); |
11c8bf9b |
259 | adns__query_fail(qu,adns_s_norecurse); |
7f702335 |
260 | } else { |
261 | adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral"); |
9b86645c |
262 | adns__query_fail(qu,adns_s_invalidresponse); |
8312a1c2 |
263 | } |
54ed1d64 |
264 | return; |
265 | } |
266 | |
8312a1c2 |
267 | /* Now, we have some RRs which we wanted. */ |
54ed1d64 |
268 | |
11c8bf9b |
269 | qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs); |
9b86645c |
270 | if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nomemory); return; } |
5c596e4d |
271 | |
f2ad23ee |
272 | typei= qu->typei; |
5c596e4d |
273 | cbyte= anstart; |
f2ad23ee |
274 | rrsdata= qu->answer->rrs.bytes; |
26eb6bdc |
275 | |
276 | pai.ads= qu->ads; |
277 | pai.qu= qu; |
278 | pai.serv= serv; |
279 | pai.dgram= dgram; |
280 | pai.dglen= dglen; |
281 | pai.nsstart= nsstart; |
282 | pai.nscount= nscount; |
283 | pai.arcount= arcount; |
ba1ddf08 |
284 | pai.now= now; |
26eb6bdc |
285 | |
286 | for (rri=0, nrrs=0; rri<ancount; rri++) { |
11c8bf9b |
287 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
2c7b101b |
288 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
11c8bf9b |
289 | &ownermatched); |
5c596e4d |
290 | assert(!st); assert(rrtype != -1); |
291 | if (rrclass != DNS_CLASS_IN || |
7f702335 |
292 | rrtype != (qu->typei->type & adns__rrt_typemask) || |
293 | !ownermatched) |
5c596e4d |
294 | continue; |
2c7b101b |
295 | adns__update_expires(qu,ttl,now); |
26eb6bdc |
296 | st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz); |
11c8bf9b |
297 | if (st) { adns__query_fail(qu,st); return; } |
7f702335 |
298 | if (rdstart==-1) goto x_truncated; |
f2ad23ee |
299 | nrrs++; |
5c596e4d |
300 | } |
f2ad23ee |
301 | assert(nrrs==wantedrrs); |
302 | qu->answer->nrrs= nrrs; |
54ed1d64 |
303 | |
5c596e4d |
304 | /* This may have generated some child queries ... */ |
305 | if (qu->children.head) { |
306 | qu->state= query_child; |
307 | LIST_LINK_TAIL(ads->childw,qu); |
308 | return; |
54ed1d64 |
309 | } |
168e26fe |
310 | |
11c8bf9b |
311 | adns__query_done(qu); |
5c596e4d |
312 | return; |
8312a1c2 |
313 | |
98db6da3 |
314 | x_truncated: |
f2ad23ee |
315 | |
5c596e4d |
316 | if (!flg_tc) { |
7f702335 |
317 | adns__diag(ads,serv,qu,"server sent datagram which points outside itself"); |
9b86645c |
318 | adns__query_fail(qu,adns_s_invalidresponse); |
5c596e4d |
319 | return; |
320 | } |
5c596e4d |
321 | qu->flags |= adns_qf_usevc; |
f2ad23ee |
322 | |
323 | x_restartquery: |
324 | |
325 | if (qu->cname_dgram) { |
326 | st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id, |
327 | qu->cname_dgram, qu->cname_dglen, qu->cname_begin, |
328 | qu->typei->type, qu->flags); |
329 | if (st) { adns__query_fail(qu,st); return; } |
330 | |
331 | newquery= realloc(qu->query_dgram,qu->vb.used); |
9b86645c |
332 | if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; } |
f2ad23ee |
333 | |
334 | qu->query_dgram= newquery; |
335 | qu->query_dglen= qu->vb.used; |
336 | memcpy(newquery,qu->vb.buf,qu->vb.used); |
337 | } |
338 | |
339 | adns__reset_cnameonly(qu); |
11c8bf9b |
340 | adns__query_udp(qu,now); |
5c596e4d |
341 | } |