e576be50 |
1 | /* |
2 | * reply.c |
3 | * - main handling and parsing routine for received datagrams |
4 | */ |
5 | /* |
6 | * This file is part of adns, which is Copyright (C) 1997, 1998 Ian Jackson |
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, |
29 | int serv, 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; |
e062dcae |
35 | int ownermatched, l, nrrs, place; |
36 | const typeinfo *typei; |
98a3f706 |
37 | adns_query qu, nqu; |
38 | dns_rcode rcode; |
b9de380c |
39 | adns_status st; |
86e7b8d9 |
40 | vbuf tempvb; |
e062dcae |
41 | byte *newquery, *rrsdata; |
ec477b9e |
42 | |
98a3f706 |
43 | if (dglen<DNS_HDRSIZE) { |
3955725c |
44 | adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen); |
ec477b9e |
45 | return; |
46 | } |
9557e604 |
47 | cbyte= 0; |
b9de380c |
48 | GET_W(cbyte,id); |
49 | GET_B(cbyte,f1); |
50 | GET_B(cbyte,f2); |
51 | GET_W(cbyte,qdcount); |
52 | GET_W(cbyte,ancount); |
53 | GET_W(cbyte,nscount); |
54 | GET_W(cbyte,arcount); |
98a3f706 |
55 | assert(cbyte == DNS_HDRSIZE); |
ec477b9e |
56 | |
31144a72 |
57 | flg_qr= f1&0x80; |
58 | opcode= (f1&0x78)>>3; |
e062dcae |
59 | flg_tc= f1&0x02; |
31144a72 |
60 | flg_rd= f1&0x01; |
0ba0614a |
61 | flg_ra= f2&0x80; |
86e7b8d9 |
62 | rcode= (f2&0x0f); |
0ba0614a |
63 | |
86e7b8d9 |
64 | cname_here= 0; |
65 | |
9557e604 |
66 | if (!flg_qr) { |
3955725c |
67 | adns__diag(ads,serv,0,"server sent us a query, not a response"); |
ec477b9e |
68 | return; |
69 | } |
31144a72 |
70 | if (opcode) { |
3955725c |
71 | adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode); |
ec477b9e |
72 | return; |
73 | } |
74 | if (!qdcount) { |
3955725c |
75 | adns__diag(ads,serv,0,"server sent reply without quoting our question"); |
ec477b9e |
76 | return; |
77 | } else if (qdcount>1) { |
3955725c |
78 | adns__diag(ads,serv,0,"server claimed to answer %d questions with one message", |
ec477b9e |
79 | qdcount); |
80 | return; |
81 | } |
98a3f706 |
82 | for (qu= ads->timew.head; qu; qu= nqu) { |
ec477b9e |
83 | nqu= qu->next; |
84 | if (qu->id != id) continue; |
3955725c |
85 | if (dglen < qu->query_dglen) continue; |
86 | if (memcmp(qu->query_dgram+DNS_HDRSIZE, |
87 | dgram+DNS_HDRSIZE, |
88 | qu->query_dglen-DNS_HDRSIZE)) |
b9de380c |
89 | continue; |
ec477b9e |
90 | break; |
91 | } |
92 | if (!qu) { |
86e7b8d9 |
93 | if (ads->iflags & adns_if_debug) { |
94 | adns__vbuf_init(&tempvb); |
95 | adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s", |
96 | id, adns__diag_domain(ads,serv,0,&tempvb,adns_qf_anyquote, |
97 | dgram,dglen,DNS_HDRSIZE)); |
98 | adns__vbuf_free(&tempvb); |
99 | } |
ec477b9e |
100 | return; |
101 | } |
86e7b8d9 |
102 | anstart= qu->query_dglen; |
98a3f706 |
103 | |
104 | LIST_UNLINK(ads->timew,qu); |
105 | /* We're definitely going to do something with this query now */ |
106 | |
b9de380c |
107 | switch (rcode) { |
108 | case rcode_noerror: |
109 | case rcode_nxdomain: |
ec477b9e |
110 | break; |
b9de380c |
111 | case rcode_formaterror: |
31144a72 |
112 | adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)"); |
3955725c |
113 | adns__query_fail(qu,adns_s_serverfaulty); |
ec477b9e |
114 | return; |
98a3f706 |
115 | case rcode_servfail: |
3955725c |
116 | adns__query_fail(qu,adns_s_servfail); |
ec477b9e |
117 | return; |
b9de380c |
118 | case rcode_notimp: |
31144a72 |
119 | adns__warn(ads,serv,qu,"server claims not to implement our query"); |
3955725c |
120 | adns__query_fail(qu,adns_s_notimplemented); |
b9de380c |
121 | return; |
122 | case rcode_refused: |
31144a72 |
123 | adns__warn(ads,serv,qu,"server refused our query"); |
3955725c |
124 | adns__query_fail(qu,adns_s_refused); |
b9de380c |
125 | return; |
126 | default: |
31144a72 |
127 | adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode); |
3955725c |
128 | adns__query_fail(qu,adns_s_reasonunknown); |
b9de380c |
129 | return; |
130 | } |
131 | |
132 | /* Now, take a look at the answer section, and see if it is complete. |
133 | * If it has any CNAMEs we stuff them in the answer. |
134 | */ |
135 | wantedrrs= 0; |
86e7b8d9 |
136 | cbyte= anstart; |
b9de380c |
137 | for (rri= 0; rri<ancount; rri++) { |
138 | rrstart= cbyte; |
3955725c |
139 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
140 | &rrtype,&rrclass,&rdlength,&rdstart, |
141 | &ownermatched); |
86e7b8d9 |
142 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
143 | if (rrtype == -1) goto x_truncated; |
144 | |
b9de380c |
145 | if (rrclass != DNS_CLASS_IN) { |
31144a72 |
146 | adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)", |
b9de380c |
147 | rrclass,DNS_CLASS_IN); |
148 | continue; |
149 | } |
0ba0614a |
150 | if (!ownermatched) { |
98a3f706 |
151 | if (ads->iflags & adns_if_debug) { |
31144a72 |
152 | adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s", |
3955725c |
153 | adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags, |
154 | dgram,dglen,rrstart)); |
0ba0614a |
155 | } |
b9de380c |
156 | continue; |
157 | } |
e062dcae |
158 | if (rrtype == adns_r_cname && /* fixme - implement adns_qf_nocname */ |
31144a72 |
159 | (qu->typei->type & adns__rrt_typemask) != adns_r_cname) { |
3955725c |
160 | if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */ |
31144a72 |
161 | qu->cname_begin= rdstart; |
31144a72 |
162 | qu->cname_dglen= dglen; |
3955725c |
163 | st= adns__parse_domain(ads,serv,qu, &qu->vb,qu->flags, |
31144a72 |
164 | dgram,dglen, &rdstart,rdstart+rdlength); |
3955725c |
165 | if (!qu->vb.used) goto x_truncated; |
166 | if (st) { adns__query_fail(qu,st); return; } |
167 | l= strlen(qu->vb.buf)+1; |
168 | qu->answer->cname= adns__alloc_interim(qu,l); |
e062dcae |
169 | if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nolocalmem); return; } |
170 | |
171 | qu->cname_dgram= adns__alloc_mine(qu,dglen); |
172 | memcpy(qu->cname_dgram,dgram,dglen); |
173 | |
3955725c |
174 | memcpy(qu->answer->cname,qu->vb.buf,l); |
86e7b8d9 |
175 | cname_here= 1; |
31144a72 |
176 | /* If we find the answer section truncated after this point we restart |
177 | * the query at the CNAME; if beforehand then we obviously have to use |
178 | * TCP. If there is no truncation we can use the whole answer if |
179 | * it contains the relevant info. |
180 | */ |
181 | } else { |
182 | adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)", |
3955725c |
183 | adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags, |
184 | dgram,dglen,rdstart), |
185 | qu->answer->cname); |
31144a72 |
186 | } |
98a3f706 |
187 | } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) { |
b9de380c |
188 | wantedrrs++; |
189 | } else { |
31144a72 |
190 | adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype); |
b9de380c |
191 | } |
192 | } |
193 | |
e062dcae |
194 | /* We defer handling truncated responses here, in case there was a CNAME |
195 | * which we could use. |
196 | */ |
197 | if (flg_tc) goto x_truncated; |
198 | |
b9de380c |
199 | nsstart= cbyte; |
200 | |
201 | if (!wantedrrs) { |
202 | /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */ |
203 | |
204 | if (rcode == rcode_nxdomain) { |
3955725c |
205 | adns__query_fail(qu,adns_s_nxdomain); |
b9de380c |
206 | return; |
207 | } |
208 | |
209 | /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */ |
0ba0614a |
210 | foundsoa= 0; foundns= 0; |
b9de380c |
211 | for (rri= 0; rri<nscount; rri++) { |
0ba0614a |
212 | rrstart= cbyte; |
3955725c |
213 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
214 | &rrtype,&rrclass,&rdlength,&rdstart, 0); |
215 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
216 | if (rrtype==-1) goto x_truncated; |
217 | if (rrclass != DNS_CLASS_IN) { |
31144a72 |
218 | adns__diag(ads,serv,qu, |
219 | "ignoring authority RR with wrong class %d (expected IN=%d)", |
0ba0614a |
220 | rrclass,DNS_CLASS_IN); |
221 | continue; |
222 | } |
223 | if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; } |
224 | else if (rrtype == adns_r_ns_raw) { foundns= 1; } |
b9de380c |
225 | } |
0ba0614a |
226 | |
227 | if (foundsoa || !foundns) { |
228 | /* Aha ! A NODATA response, good. */ |
3955725c |
229 | adns__query_fail(qu,adns_s_nodata); |
0ba0614a |
230 | return; |
231 | } |
232 | |
233 | /* Now what ? No relevant answers, no SOA, and at least some NS's. |
234 | * Looks like a referral. Just one last chance ... if we came across |
31144a72 |
235 | * a CNAME in this datagram then we should probably do our own CNAME |
236 | * lookup now in the hope that we won't get a referral again. |
0ba0614a |
237 | */ |
e062dcae |
238 | if (cname_here) goto x_restartquery; |
0ba0614a |
239 | |
240 | /* Bloody hell, I thought we asked for recursion ? */ |
31144a72 |
241 | if (flg_rd) { |
242 | adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup"); |
243 | } |
0ba0614a |
244 | if (!flg_ra) { |
31144a72 |
245 | adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us"); |
3955725c |
246 | adns__query_fail(qu,adns_s_norecurse); |
31144a72 |
247 | } else { |
248 | adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral"); |
3955725c |
249 | adns__query_fail(qu,adns_s_serverfaulty); |
0ba0614a |
250 | } |
b9de380c |
251 | return; |
252 | } |
253 | |
0ba0614a |
254 | /* Now, we have some RRs which we wanted. */ |
b9de380c |
255 | |
3955725c |
256 | qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs); |
e062dcae |
257 | if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nolocalmem); return; } |
98a3f706 |
258 | |
e062dcae |
259 | typei= qu->typei; |
98a3f706 |
260 | cbyte= anstart; |
98a3f706 |
261 | arstart= -1; |
e062dcae |
262 | rrsdata= qu->answer->rrs.bytes; |
263 | |
264 | if (typei->diff_needswap) { |
265 | if (!adns__vbuf_ensure(&qu->vb,typei->rrsz)) { |
266 | adns__query_fail(qu,adns_s_nolocalmem); |
267 | return; |
268 | } |
269 | } |
270 | nrrs= 0; |
271 | |
98a3f706 |
272 | for (rri=0; rri<ancount; rri++) { |
3955725c |
273 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
274 | &rrtype,&rrclass,&rdlength,&rdstart, |
275 | &ownermatched); |
98a3f706 |
276 | assert(!st); assert(rrtype != -1); |
277 | if (rrclass != DNS_CLASS_IN || |
31144a72 |
278 | rrtype != (qu->typei->type & adns__rrt_typemask) || |
279 | !ownermatched) |
98a3f706 |
280 | continue; |
e062dcae |
281 | st= typei->parse(qu,serv, dgram,dglen, rdstart,rdstart+rdlength, |
282 | rrsdata+nrrs*typei->rrsz); |
3955725c |
283 | if (st) { adns__query_fail(qu,st); return; } |
31144a72 |
284 | if (rdstart==-1) goto x_truncated; |
e062dcae |
285 | |
286 | if (typei->diff_needswap) { |
287 | for (place= nrrs; |
288 | place>0 && typei->diff_needswap(rrsdata+(place-1)*typei->rrsz, |
289 | rrsdata+nrrs*typei->rrsz); |
290 | place--); |
291 | if (place != nrrs) { |
292 | memcpy(qu->vb.buf,rrsdata+nrrs*typei->rrsz,typei->rrsz); |
293 | memmove(rrsdata+(place+1)*typei->rrsz, |
294 | rrsdata+place*typei->rrsz, |
295 | (nrrs-place)*typei->rrsz); |
296 | memcpy(rrsdata+place*typei->rrsz,qu->vb.buf,typei->rrsz); |
297 | } |
298 | } |
299 | nrrs++; |
98a3f706 |
300 | } |
e062dcae |
301 | assert(nrrs==wantedrrs); |
302 | qu->answer->nrrs= nrrs; |
b9de380c |
303 | |
98a3f706 |
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; |
b9de380c |
309 | } |
ec477b9e |
310 | |
3955725c |
311 | adns__query_done(qu); |
98a3f706 |
312 | return; |
0ba0614a |
313 | |
e576be50 |
314 | x_truncated: |
e062dcae |
315 | |
98a3f706 |
316 | if (!flg_tc) { |
31144a72 |
317 | adns__diag(ads,serv,qu,"server sent datagram which points outside itself"); |
3955725c |
318 | adns__query_fail(qu,adns_s_serverfaulty); |
98a3f706 |
319 | return; |
320 | } |
98a3f706 |
321 | qu->flags |= adns_qf_usevc; |
e062dcae |
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); |
332 | if (!newquery) { adns__query_fail(qu,adns_s_nolocalmem); return; } |
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); |
3955725c |
340 | adns__query_udp(qu,now); |
98a3f706 |
341 | } |