e576be50 |
1 | /* |
2 | * reply.c |
3 | * - main handling and parsing routine for received datagrams |
4 | */ |
5 | /* |
d942707d |
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> |
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) { |
3955725c |
50 | adns__diag(ads,serv,0,"received datagram 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) { |
3955725c |
77 | adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode); |
ec477b9e |
78 | return; |
79 | } |
80 | if (!qdcount) { |
3955725c |
81 | adns__diag(ads,serv,0,"server sent reply without quoting our question"); |
ec477b9e |
82 | return; |
83 | } else if (qdcount>1) { |
3955725c |
84 | adns__diag(ads,serv,0,"server claimed to answer %d questions with one message", |
ec477b9e |
85 | qdcount); |
86 | return; |
87 | } |
98a3f706 |
88 | for (qu= ads->timew.head; qu; qu= nqu) { |
ec477b9e |
89 | nqu= qu->next; |
90 | if (qu->id != id) continue; |
3955725c |
91 | if (dglen < qu->query_dglen) continue; |
92 | if (memcmp(qu->query_dgram+DNS_HDRSIZE, |
93 | dgram+DNS_HDRSIZE, |
94 | qu->query_dglen-DNS_HDRSIZE)) |
b9de380c |
95 | continue; |
ebf4877a |
96 | if (viatcp) { |
97 | if (qu->state != query_tcpsent) continue; |
98 | } else { |
99 | if (qu->state != query_tosend) continue; |
100 | if (!(qu->udpsent & (1<<serv))) continue; |
101 | } |
ec477b9e |
102 | break; |
103 | } |
104 | if (!qu) { |
86e7b8d9 |
105 | if (ads->iflags & adns_if_debug) { |
106 | adns__vbuf_init(&tempvb); |
107 | adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s", |
828d89bd |
108 | id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE)); |
86e7b8d9 |
109 | adns__vbuf_free(&tempvb); |
110 | } |
ec477b9e |
111 | return; |
112 | } |
86e7b8d9 |
113 | anstart= qu->query_dglen; |
88372443 |
114 | arstart= -1; |
98a3f706 |
115 | |
116 | LIST_UNLINK(ads->timew,qu); |
117 | /* We're definitely going to do something with this query now */ |
118 | |
b9de380c |
119 | switch (rcode) { |
120 | case rcode_noerror: |
121 | case rcode_nxdomain: |
ec477b9e |
122 | break; |
b9de380c |
123 | case rcode_formaterror: |
31144a72 |
124 | adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)"); |
ea1e31e3 |
125 | adns__query_fail(qu,adns_s_rcodeformaterror); |
ec477b9e |
126 | return; |
98a3f706 |
127 | case rcode_servfail: |
ea1e31e3 |
128 | adns__query_fail(qu,adns_s_rcodeservfail); |
ec477b9e |
129 | return; |
b9de380c |
130 | case rcode_notimp: |
31144a72 |
131 | adns__warn(ads,serv,qu,"server claims not to implement our query"); |
ea1e31e3 |
132 | adns__query_fail(qu,adns_s_rcodenotimplemented); |
b9de380c |
133 | return; |
134 | case rcode_refused: |
31144a72 |
135 | adns__warn(ads,serv,qu,"server refused our query"); |
ea1e31e3 |
136 | adns__query_fail(qu,adns_s_rcoderefused); |
b9de380c |
137 | return; |
138 | default: |
31144a72 |
139 | adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode); |
ea1e31e3 |
140 | adns__query_fail(qu,adns_s_rcodeunknown); |
b9de380c |
141 | return; |
142 | } |
143 | |
144 | /* Now, take a look at the answer section, and see if it is complete. |
145 | * If it has any CNAMEs we stuff them in the answer. |
146 | */ |
147 | wantedrrs= 0; |
86e7b8d9 |
148 | cbyte= anstart; |
b9de380c |
149 | for (rri= 0; rri<ancount; rri++) { |
150 | rrstart= cbyte; |
3955725c |
151 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
152 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
3955725c |
153 | &ownermatched); |
86e7b8d9 |
154 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
155 | if (rrtype == -1) goto x_truncated; |
156 | |
b9de380c |
157 | if (rrclass != DNS_CLASS_IN) { |
31144a72 |
158 | adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)", |
b9de380c |
159 | rrclass,DNS_CLASS_IN); |
160 | continue; |
161 | } |
0ba0614a |
162 | if (!ownermatched) { |
98a3f706 |
163 | if (ads->iflags & adns_if_debug) { |
31144a72 |
164 | adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s", |
828d89bd |
165 | adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rrstart)); |
0ba0614a |
166 | } |
b9de380c |
167 | continue; |
168 | } |
2a6d6736 |
169 | if (rrtype == adns_r_cname && |
31144a72 |
170 | (qu->typei->type & adns__rrt_typemask) != adns_r_cname) { |
4b707d8b |
171 | if (qu->flags & adns_qf_cname_forbid) { |
172 | adns__query_fail(qu,adns_s_prohibitedcname); |
173 | return; |
636b69b1 |
174 | } else if (qu->cname_dgram) { /* Ignore second and subsequent CNAME(s) */ |
05db5bce |
175 | adns__debug(ads,serv,qu,"allegedly canonical name %s is actually alias for %s", |
176 | qu->answer->cname, |
177 | adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart)); |
178 | adns__query_fail(qu,adns_s_prohibitedcname); |
179 | return; |
636b69b1 |
180 | } else if (wantedrrs) { /* Ignore CNAME(s) after RR(s). */ |
181 | adns__debug(ads,serv,qu,"ignoring CNAME (to %s) coexisting with RR", |
182 | adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart)); |
183 | } else { |
31144a72 |
184 | qu->cname_begin= rdstart; |
31144a72 |
185 | qu->cname_dglen= dglen; |
828d89bd |
186 | st= adns__parse_domain(ads,serv,qu, &qu->vb, |
187 | qu->flags & adns_qf_quoteok_cname ? pdf_quoteok : 0, |
31144a72 |
188 | dgram,dglen, &rdstart,rdstart+rdlength); |
3955725c |
189 | if (!qu->vb.used) goto x_truncated; |
190 | if (st) { adns__query_fail(qu,st); return; } |
191 | l= strlen(qu->vb.buf)+1; |
8b3d55e3 |
192 | qu->answer->cname= adns__alloc_preserved(qu,l); |
ea1e31e3 |
193 | if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; } |
e062dcae |
194 | |
195 | qu->cname_dgram= adns__alloc_mine(qu,dglen); |
196 | memcpy(qu->cname_dgram,dgram,dglen); |
197 | |
3955725c |
198 | memcpy(qu->answer->cname,qu->vb.buf,l); |
86e7b8d9 |
199 | cname_here= 1; |
73dba56e |
200 | adns__update_expires(qu,ttl,now); |
31144a72 |
201 | /* If we find the answer section truncated after this point we restart |
202 | * the query at the CNAME; if beforehand then we obviously have to use |
203 | * TCP. If there is no truncation we can use the whole answer if |
204 | * it contains the relevant info. |
205 | */ |
31144a72 |
206 | } |
98a3f706 |
207 | } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) { |
b9de380c |
208 | wantedrrs++; |
209 | } else { |
31144a72 |
210 | adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype); |
b9de380c |
211 | } |
212 | } |
213 | |
e062dcae |
214 | /* We defer handling truncated responses here, in case there was a CNAME |
215 | * which we could use. |
216 | */ |
217 | if (flg_tc) goto x_truncated; |
218 | |
b9de380c |
219 | nsstart= cbyte; |
220 | |
221 | if (!wantedrrs) { |
222 | /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */ |
b9de380c |
223 | |
224 | /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */ |
73dba56e |
225 | foundsoa= 0; soattl= 0; foundns= 0; |
b9de380c |
226 | for (rri= 0; rri<nscount; rri++) { |
0ba0614a |
227 | rrstart= cbyte; |
3955725c |
228 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
229 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0); |
3955725c |
230 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
231 | if (rrtype==-1) goto x_truncated; |
232 | if (rrclass != DNS_CLASS_IN) { |
31144a72 |
233 | adns__diag(ads,serv,qu, |
234 | "ignoring authority RR with wrong class %d (expected IN=%d)", |
0ba0614a |
235 | rrclass,DNS_CLASS_IN); |
236 | continue; |
237 | } |
73dba56e |
238 | if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; } |
0ba0614a |
239 | else if (rrtype == adns_r_ns_raw) { foundns= 1; } |
b9de380c |
240 | } |
73dba56e |
241 | |
242 | if (rcode == rcode_nxdomain) { |
243 | /* We still wanted to look for the SOA so we could find the TTL. */ |
244 | adns__update_expires(qu,soattl,now); |
660d7d3b |
245 | |
246 | if (qu->flags & adns_qf_search) { |
247 | adns__search_next(ads,qu,now); |
248 | } else { |
249 | adns__query_fail(qu,adns_s_nxdomain); |
250 | } |
73dba56e |
251 | return; |
252 | } |
0ba0614a |
253 | |
254 | if (foundsoa || !foundns) { |
255 | /* Aha ! A NODATA response, good. */ |
73dba56e |
256 | adns__update_expires(qu,soattl,now); |
3955725c |
257 | adns__query_fail(qu,adns_s_nodata); |
0ba0614a |
258 | return; |
259 | } |
260 | |
261 | /* Now what ? No relevant answers, no SOA, and at least some NS's. |
262 | * Looks like a referral. Just one last chance ... if we came across |
31144a72 |
263 | * a CNAME in this datagram then we should probably do our own CNAME |
264 | * lookup now in the hope that we won't get a referral again. |
0ba0614a |
265 | */ |
e062dcae |
266 | if (cname_here) goto x_restartquery; |
0ba0614a |
267 | |
268 | /* Bloody hell, I thought we asked for recursion ? */ |
31144a72 |
269 | if (flg_rd) { |
270 | adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup"); |
271 | } |
0ba0614a |
272 | if (!flg_ra) { |
31144a72 |
273 | adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us"); |
3955725c |
274 | adns__query_fail(qu,adns_s_norecurse); |
31144a72 |
275 | } else { |
276 | adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral"); |
ea1e31e3 |
277 | adns__query_fail(qu,adns_s_invalidresponse); |
0ba0614a |
278 | } |
b9de380c |
279 | return; |
280 | } |
281 | |
0ba0614a |
282 | /* Now, we have some RRs which we wanted. */ |
b9de380c |
283 | |
3955725c |
284 | qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs); |
ea1e31e3 |
285 | if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nomemory); return; } |
98a3f706 |
286 | |
e062dcae |
287 | typei= qu->typei; |
98a3f706 |
288 | cbyte= anstart; |
e062dcae |
289 | rrsdata= qu->answer->rrs.bytes; |
1dfe95d8 |
290 | |
291 | pai.ads= qu->ads; |
292 | pai.qu= qu; |
293 | pai.serv= serv; |
294 | pai.dgram= dgram; |
295 | pai.dglen= dglen; |
296 | pai.nsstart= nsstart; |
297 | pai.nscount= nscount; |
298 | pai.arcount= arcount; |
7da21070 |
299 | pai.now= now; |
1dfe95d8 |
300 | |
301 | for (rri=0, nrrs=0; rri<ancount; rri++) { |
3955725c |
302 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
303 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
3955725c |
304 | &ownermatched); |
98a3f706 |
305 | assert(!st); assert(rrtype != -1); |
306 | if (rrclass != DNS_CLASS_IN || |
31144a72 |
307 | rrtype != (qu->typei->type & adns__rrt_typemask) || |
308 | !ownermatched) |
98a3f706 |
309 | continue; |
73dba56e |
310 | adns__update_expires(qu,ttl,now); |
1dfe95d8 |
311 | st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz); |
3955725c |
312 | if (st) { adns__query_fail(qu,st); return; } |
31144a72 |
313 | if (rdstart==-1) goto x_truncated; |
e062dcae |
314 | nrrs++; |
98a3f706 |
315 | } |
e062dcae |
316 | assert(nrrs==wantedrrs); |
317 | qu->answer->nrrs= nrrs; |
b9de380c |
318 | |
98a3f706 |
319 | /* This may have generated some child queries ... */ |
320 | if (qu->children.head) { |
321 | qu->state= query_child; |
322 | LIST_LINK_TAIL(ads->childw,qu); |
323 | return; |
b9de380c |
324 | } |
3955725c |
325 | adns__query_done(qu); |
98a3f706 |
326 | return; |
0ba0614a |
327 | |
e576be50 |
328 | x_truncated: |
e062dcae |
329 | |
98a3f706 |
330 | if (!flg_tc) { |
31144a72 |
331 | adns__diag(ads,serv,qu,"server sent datagram which points outside itself"); |
ea1e31e3 |
332 | adns__query_fail(qu,adns_s_invalidresponse); |
98a3f706 |
333 | return; |
334 | } |
98a3f706 |
335 | qu->flags |= adns_qf_usevc; |
e062dcae |
336 | |
337 | x_restartquery: |
e062dcae |
338 | if (qu->cname_dgram) { |
339 | st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id, |
340 | qu->cname_dgram, qu->cname_dglen, qu->cname_begin, |
341 | qu->typei->type, qu->flags); |
342 | if (st) { adns__query_fail(qu,st); return; } |
343 | |
344 | newquery= realloc(qu->query_dgram,qu->vb.used); |
ea1e31e3 |
345 | if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; } |
e062dcae |
346 | |
347 | qu->query_dgram= newquery; |
348 | qu->query_dglen= qu->vb.used; |
349 | memcpy(newquery,qu->vb.buf,qu->vb.used); |
350 | } |
351 | |
d8c062fa |
352 | if (qu->state == query_tcpsent) qu->state= query_tosend; |
8b3d55e3 |
353 | adns__reset_preserved(qu); |
d8c062fa |
354 | adns__query_send(qu,now); |
98a3f706 |
355 | } |