e576be50 |
1 | /* |
2 | * reply.c |
3 | * - main handling and parsing routine for received datagrams |
4 | */ |
5 | /* |
a719a4be |
6 | * This file is part of adns, which is Copyright (C) 1997-1999 Ian Jackson |
e576be50 |
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 | */ |
4353a5c4 |
22 | |
e062dcae |
23 | #include <stdlib.h> |
24 | #include <string.h> |
4353a5c4 |
25 | |
e062dcae |
26 | #include "internal.h" |
b9de380c |
27 | |
98a3f706 |
28 | void adns__procdgram(adns_state ads, const byte *dgram, int dglen, |
ebf4877a |
29 | int serv, int viatcp, struct timeval now) { |
86e7b8d9 |
30 | int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here; |
3955725c |
31 | int id, f1, f2, qdcount, ancount, nscount, arcount; |
32 | int flg_ra, flg_rd, flg_tc, flg_qr, opcode; |
e062dcae |
33 | int rrtype, rrclass, rdlength, rdstart; |
98a3f706 |
34 | int anstart, nsstart, arstart; |
88372443 |
35 | int ownermatched, l, nrrs; |
73dba56e |
36 | unsigned long ttl, soattl; |
e062dcae |
37 | const typeinfo *typei; |
98a3f706 |
38 | adns_query qu, nqu; |
39 | dns_rcode rcode; |
b9de380c |
40 | adns_status st; |
86e7b8d9 |
41 | vbuf tempvb; |
e062dcae |
42 | byte *newquery, *rrsdata; |
1dfe95d8 |
43 | parseinfo pai; |
ec477b9e |
44 | |
98a3f706 |
45 | if (dglen<DNS_HDRSIZE) { |
3955725c |
46 | adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen); |
ec477b9e |
47 | return; |
48 | } |
9557e604 |
49 | cbyte= 0; |
b9de380c |
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); |
98a3f706 |
57 | assert(cbyte == DNS_HDRSIZE); |
ec477b9e |
58 | |
31144a72 |
59 | flg_qr= f1&0x80; |
60 | opcode= (f1&0x78)>>3; |
e062dcae |
61 | flg_tc= f1&0x02; |
31144a72 |
62 | flg_rd= f1&0x01; |
0ba0614a |
63 | flg_ra= f2&0x80; |
86e7b8d9 |
64 | rcode= (f2&0x0f); |
0ba0614a |
65 | |
86e7b8d9 |
66 | cname_here= 0; |
67 | |
9557e604 |
68 | if (!flg_qr) { |
3955725c |
69 | adns__diag(ads,serv,0,"server sent us a query, not a response"); |
ec477b9e |
70 | return; |
71 | } |
31144a72 |
72 | if (opcode) { |
3955725c |
73 | adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode); |
ec477b9e |
74 | return; |
75 | } |
76 | if (!qdcount) { |
3955725c |
77 | adns__diag(ads,serv,0,"server sent reply without quoting our question"); |
ec477b9e |
78 | return; |
79 | } else if (qdcount>1) { |
3955725c |
80 | adns__diag(ads,serv,0,"server claimed to answer %d questions with one message", |
ec477b9e |
81 | qdcount); |
82 | return; |
83 | } |
98a3f706 |
84 | for (qu= ads->timew.head; qu; qu= nqu) { |
ec477b9e |
85 | nqu= qu->next; |
86 | if (qu->id != id) continue; |
3955725c |
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)) |
b9de380c |
91 | continue; |
ebf4877a |
92 | if (viatcp) { |
93 | if (qu->state != query_tcpsent) continue; |
94 | } else { |
95 | if (qu->state != query_tosend) continue; |
96 | if (!(qu->udpsent & (1<<serv))) continue; |
97 | } |
ec477b9e |
98 | break; |
99 | } |
100 | if (!qu) { |
86e7b8d9 |
101 | if (ads->iflags & adns_if_debug) { |
102 | adns__vbuf_init(&tempvb); |
103 | adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s", |
828d89bd |
104 | id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE)); |
86e7b8d9 |
105 | adns__vbuf_free(&tempvb); |
106 | } |
ec477b9e |
107 | return; |
108 | } |
86e7b8d9 |
109 | anstart= qu->query_dglen; |
88372443 |
110 | arstart= -1; |
98a3f706 |
111 | |
112 | LIST_UNLINK(ads->timew,qu); |
113 | /* We're definitely going to do something with this query now */ |
114 | |
b9de380c |
115 | switch (rcode) { |
116 | case rcode_noerror: |
117 | case rcode_nxdomain: |
ec477b9e |
118 | break; |
b9de380c |
119 | case rcode_formaterror: |
31144a72 |
120 | adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)"); |
ea1e31e3 |
121 | adns__query_fail(qu,adns_s_rcodeformaterror); |
ec477b9e |
122 | return; |
98a3f706 |
123 | case rcode_servfail: |
ea1e31e3 |
124 | adns__query_fail(qu,adns_s_rcodeservfail); |
ec477b9e |
125 | return; |
b9de380c |
126 | case rcode_notimp: |
31144a72 |
127 | adns__warn(ads,serv,qu,"server claims not to implement our query"); |
ea1e31e3 |
128 | adns__query_fail(qu,adns_s_rcodenotimplemented); |
b9de380c |
129 | return; |
130 | case rcode_refused: |
31144a72 |
131 | adns__warn(ads,serv,qu,"server refused our query"); |
ea1e31e3 |
132 | 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); |
ea1e31e3 |
136 | adns__query_fail(qu,adns_s_rcodeunknown); |
b9de380c |
137 | return; |
138 | } |
139 | |
140 | /* Now, take a look at the answer section, and see if it is complete. |
141 | * If it has any CNAMEs we stuff them in the answer. |
142 | */ |
143 | wantedrrs= 0; |
86e7b8d9 |
144 | cbyte= anstart; |
b9de380c |
145 | for (rri= 0; rri<ancount; rri++) { |
146 | rrstart= cbyte; |
3955725c |
147 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
148 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
3955725c |
149 | &ownermatched); |
86e7b8d9 |
150 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
151 | if (rrtype == -1) goto x_truncated; |
152 | |
b9de380c |
153 | if (rrclass != DNS_CLASS_IN) { |
31144a72 |
154 | adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)", |
b9de380c |
155 | rrclass,DNS_CLASS_IN); |
156 | continue; |
157 | } |
0ba0614a |
158 | if (!ownermatched) { |
98a3f706 |
159 | if (ads->iflags & adns_if_debug) { |
31144a72 |
160 | adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s", |
828d89bd |
161 | adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rrstart)); |
0ba0614a |
162 | } |
b9de380c |
163 | continue; |
164 | } |
2a6d6736 |
165 | if (rrtype == adns_r_cname && |
31144a72 |
166 | (qu->typei->type & adns__rrt_typemask) != adns_r_cname) { |
4b707d8b |
167 | if (qu->flags & adns_qf_cname_forbid) { |
168 | adns__query_fail(qu,adns_s_prohibitedcname); |
169 | return; |
170 | } else if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */ |
31144a72 |
171 | qu->cname_begin= rdstart; |
31144a72 |
172 | qu->cname_dglen= dglen; |
828d89bd |
173 | st= adns__parse_domain(ads,serv,qu, &qu->vb, |
174 | qu->flags & adns_qf_quoteok_cname ? pdf_quoteok : 0, |
31144a72 |
175 | dgram,dglen, &rdstart,rdstart+rdlength); |
3955725c |
176 | if (!qu->vb.used) goto x_truncated; |
177 | if (st) { adns__query_fail(qu,st); return; } |
178 | l= strlen(qu->vb.buf)+1; |
8b3d55e3 |
179 | qu->answer->cname= adns__alloc_preserved(qu,l); |
ea1e31e3 |
180 | if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; } |
e062dcae |
181 | |
182 | qu->cname_dgram= adns__alloc_mine(qu,dglen); |
183 | memcpy(qu->cname_dgram,dgram,dglen); |
184 | |
3955725c |
185 | memcpy(qu->answer->cname,qu->vb.buf,l); |
86e7b8d9 |
186 | cname_here= 1; |
73dba56e |
187 | adns__update_expires(qu,ttl,now); |
31144a72 |
188 | /* If we find the answer section truncated after this point we restart |
189 | * the query at the CNAME; if beforehand then we obviously have to use |
190 | * TCP. If there is no truncation we can use the whole answer if |
191 | * it contains the relevant info. |
192 | */ |
193 | } else { |
194 | adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)", |
828d89bd |
195 | adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart), |
3955725c |
196 | qu->answer->cname); |
31144a72 |
197 | } |
98a3f706 |
198 | } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) { |
b9de380c |
199 | wantedrrs++; |
200 | } else { |
31144a72 |
201 | adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype); |
b9de380c |
202 | } |
203 | } |
204 | |
e062dcae |
205 | /* We defer handling truncated responses here, in case there was a CNAME |
206 | * which we could use. |
207 | */ |
208 | if (flg_tc) goto x_truncated; |
209 | |
b9de380c |
210 | nsstart= cbyte; |
211 | |
212 | if (!wantedrrs) { |
213 | /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */ |
b9de380c |
214 | |
215 | /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */ |
73dba56e |
216 | foundsoa= 0; soattl= 0; foundns= 0; |
b9de380c |
217 | for (rri= 0; rri<nscount; rri++) { |
0ba0614a |
218 | rrstart= cbyte; |
3955725c |
219 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
220 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, 0); |
3955725c |
221 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
222 | if (rrtype==-1) goto x_truncated; |
223 | if (rrclass != DNS_CLASS_IN) { |
31144a72 |
224 | adns__diag(ads,serv,qu, |
225 | "ignoring authority RR with wrong class %d (expected IN=%d)", |
0ba0614a |
226 | rrclass,DNS_CLASS_IN); |
227 | continue; |
228 | } |
73dba56e |
229 | if (rrtype == adns_r_soa_raw) { foundsoa= 1; soattl= ttl; break; } |
0ba0614a |
230 | else if (rrtype == adns_r_ns_raw) { foundns= 1; } |
b9de380c |
231 | } |
73dba56e |
232 | |
233 | if (rcode == rcode_nxdomain) { |
234 | /* We still wanted to look for the SOA so we could find the TTL. */ |
235 | adns__update_expires(qu,soattl,now); |
660d7d3b |
236 | |
237 | if (qu->flags & adns_qf_search) { |
238 | adns__search_next(ads,qu,now); |
239 | } else { |
240 | adns__query_fail(qu,adns_s_nxdomain); |
241 | } |
73dba56e |
242 | return; |
243 | } |
0ba0614a |
244 | |
245 | if (foundsoa || !foundns) { |
246 | /* Aha ! A NODATA response, good. */ |
73dba56e |
247 | adns__update_expires(qu,soattl,now); |
3955725c |
248 | adns__query_fail(qu,adns_s_nodata); |
0ba0614a |
249 | return; |
250 | } |
251 | |
252 | /* Now what ? No relevant answers, no SOA, and at least some NS's. |
253 | * Looks like a referral. Just one last chance ... if we came across |
31144a72 |
254 | * a CNAME in this datagram then we should probably do our own CNAME |
255 | * lookup now in the hope that we won't get a referral again. |
0ba0614a |
256 | */ |
e062dcae |
257 | if (cname_here) goto x_restartquery; |
0ba0614a |
258 | |
259 | /* Bloody hell, I thought we asked for recursion ? */ |
31144a72 |
260 | if (flg_rd) { |
261 | adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup"); |
262 | } |
0ba0614a |
263 | if (!flg_ra) { |
31144a72 |
264 | adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us"); |
3955725c |
265 | adns__query_fail(qu,adns_s_norecurse); |
31144a72 |
266 | } else { |
267 | adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral"); |
ea1e31e3 |
268 | adns__query_fail(qu,adns_s_invalidresponse); |
0ba0614a |
269 | } |
b9de380c |
270 | return; |
271 | } |
272 | |
0ba0614a |
273 | /* Now, we have some RRs which we wanted. */ |
b9de380c |
274 | |
3955725c |
275 | qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs); |
ea1e31e3 |
276 | if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nomemory); return; } |
98a3f706 |
277 | |
e062dcae |
278 | typei= qu->typei; |
98a3f706 |
279 | cbyte= anstart; |
e062dcae |
280 | rrsdata= qu->answer->rrs.bytes; |
1dfe95d8 |
281 | |
282 | pai.ads= qu->ads; |
283 | pai.qu= qu; |
284 | pai.serv= serv; |
285 | pai.dgram= dgram; |
286 | pai.dglen= dglen; |
287 | pai.nsstart= nsstart; |
288 | pai.nscount= nscount; |
289 | pai.arcount= arcount; |
7da21070 |
290 | pai.now= now; |
1dfe95d8 |
291 | |
292 | for (rri=0, nrrs=0; rri<ancount; rri++) { |
3955725c |
293 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
73dba56e |
294 | &rrtype,&rrclass,&ttl, &rdlength,&rdstart, |
3955725c |
295 | &ownermatched); |
98a3f706 |
296 | assert(!st); assert(rrtype != -1); |
297 | if (rrclass != DNS_CLASS_IN || |
31144a72 |
298 | rrtype != (qu->typei->type & adns__rrt_typemask) || |
299 | !ownermatched) |
98a3f706 |
300 | continue; |
73dba56e |
301 | adns__update_expires(qu,ttl,now); |
1dfe95d8 |
302 | st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz); |
3955725c |
303 | if (st) { adns__query_fail(qu,st); return; } |
31144a72 |
304 | if (rdstart==-1) goto x_truncated; |
e062dcae |
305 | nrrs++; |
98a3f706 |
306 | } |
e062dcae |
307 | assert(nrrs==wantedrrs); |
308 | qu->answer->nrrs= nrrs; |
b9de380c |
309 | |
98a3f706 |
310 | /* This may have generated some child queries ... */ |
311 | if (qu->children.head) { |
312 | qu->state= query_child; |
313 | LIST_LINK_TAIL(ads->childw,qu); |
314 | return; |
b9de380c |
315 | } |
3955725c |
316 | adns__query_done(qu); |
98a3f706 |
317 | return; |
0ba0614a |
318 | |
e576be50 |
319 | x_truncated: |
e062dcae |
320 | |
98a3f706 |
321 | if (!flg_tc) { |
31144a72 |
322 | adns__diag(ads,serv,qu,"server sent datagram which points outside itself"); |
ea1e31e3 |
323 | adns__query_fail(qu,adns_s_invalidresponse); |
98a3f706 |
324 | return; |
325 | } |
98a3f706 |
326 | qu->flags |= adns_qf_usevc; |
e062dcae |
327 | |
328 | x_restartquery: |
e062dcae |
329 | if (qu->cname_dgram) { |
330 | st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id, |
331 | qu->cname_dgram, qu->cname_dglen, qu->cname_begin, |
332 | qu->typei->type, qu->flags); |
333 | if (st) { adns__query_fail(qu,st); return; } |
334 | |
335 | newquery= realloc(qu->query_dgram,qu->vb.used); |
ea1e31e3 |
336 | if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; } |
e062dcae |
337 | |
338 | qu->query_dgram= newquery; |
339 | qu->query_dglen= qu->vb.used; |
340 | memcpy(newquery,qu->vb.buf,qu->vb.used); |
341 | } |
342 | |
d8c062fa |
343 | if (qu->state == query_tcpsent) qu->state= query_tosend; |
8b3d55e3 |
344 | adns__reset_preserved(qu); |
d8c062fa |
345 | adns__query_send(qu,now); |
98a3f706 |
346 | } |