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; |
88372443 |
35 | int ownermatched, l, nrrs; |
e062dcae |
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; |
1dfe95d8 |
42 | parseinfo pai; |
ec477b9e |
43 | |
98a3f706 |
44 | if (dglen<DNS_HDRSIZE) { |
3955725c |
45 | adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen); |
ec477b9e |
46 | return; |
47 | } |
9557e604 |
48 | cbyte= 0; |
b9de380c |
49 | GET_W(cbyte,id); |
50 | GET_B(cbyte,f1); |
51 | GET_B(cbyte,f2); |
52 | GET_W(cbyte,qdcount); |
53 | GET_W(cbyte,ancount); |
54 | GET_W(cbyte,nscount); |
55 | GET_W(cbyte,arcount); |
98a3f706 |
56 | assert(cbyte == DNS_HDRSIZE); |
ec477b9e |
57 | |
31144a72 |
58 | flg_qr= f1&0x80; |
59 | opcode= (f1&0x78)>>3; |
e062dcae |
60 | flg_tc= f1&0x02; |
31144a72 |
61 | flg_rd= f1&0x01; |
0ba0614a |
62 | flg_ra= f2&0x80; |
86e7b8d9 |
63 | rcode= (f2&0x0f); |
0ba0614a |
64 | |
86e7b8d9 |
65 | cname_here= 0; |
66 | |
9557e604 |
67 | if (!flg_qr) { |
3955725c |
68 | adns__diag(ads,serv,0,"server sent us a query, not a response"); |
ec477b9e |
69 | return; |
70 | } |
31144a72 |
71 | if (opcode) { |
3955725c |
72 | adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode); |
ec477b9e |
73 | return; |
74 | } |
75 | if (!qdcount) { |
3955725c |
76 | adns__diag(ads,serv,0,"server sent reply without quoting our question"); |
ec477b9e |
77 | return; |
78 | } else if (qdcount>1) { |
3955725c |
79 | adns__diag(ads,serv,0,"server claimed to answer %d questions with one message", |
ec477b9e |
80 | qdcount); |
81 | return; |
82 | } |
98a3f706 |
83 | for (qu= ads->timew.head; qu; qu= nqu) { |
ec477b9e |
84 | nqu= qu->next; |
85 | if (qu->id != id) continue; |
3955725c |
86 | if (dglen < qu->query_dglen) continue; |
87 | if (memcmp(qu->query_dgram+DNS_HDRSIZE, |
88 | dgram+DNS_HDRSIZE, |
89 | qu->query_dglen-DNS_HDRSIZE)) |
b9de380c |
90 | continue; |
ec477b9e |
91 | break; |
92 | } |
93 | if (!qu) { |
86e7b8d9 |
94 | if (ads->iflags & adns_if_debug) { |
95 | adns__vbuf_init(&tempvb); |
96 | adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s", |
828d89bd |
97 | id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE)); |
86e7b8d9 |
98 | adns__vbuf_free(&tempvb); |
99 | } |
ec477b9e |
100 | return; |
101 | } |
86e7b8d9 |
102 | anstart= qu->query_dglen; |
88372443 |
103 | arstart= -1; |
98a3f706 |
104 | |
105 | LIST_UNLINK(ads->timew,qu); |
106 | /* We're definitely going to do something with this query now */ |
107 | |
b9de380c |
108 | switch (rcode) { |
109 | case rcode_noerror: |
110 | case rcode_nxdomain: |
ec477b9e |
111 | break; |
b9de380c |
112 | case rcode_formaterror: |
31144a72 |
113 | adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)"); |
ea1e31e3 |
114 | adns__query_fail(qu,adns_s_rcodeformaterror); |
ec477b9e |
115 | return; |
98a3f706 |
116 | case rcode_servfail: |
ea1e31e3 |
117 | adns__query_fail(qu,adns_s_rcodeservfail); |
ec477b9e |
118 | return; |
b9de380c |
119 | case rcode_notimp: |
31144a72 |
120 | adns__warn(ads,serv,qu,"server claims not to implement our query"); |
ea1e31e3 |
121 | adns__query_fail(qu,adns_s_rcodenotimplemented); |
b9de380c |
122 | return; |
123 | case rcode_refused: |
31144a72 |
124 | adns__warn(ads,serv,qu,"server refused our query"); |
ea1e31e3 |
125 | adns__query_fail(qu,adns_s_rcoderefused); |
b9de380c |
126 | return; |
127 | default: |
31144a72 |
128 | adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode); |
ea1e31e3 |
129 | adns__query_fail(qu,adns_s_rcodeunknown); |
b9de380c |
130 | return; |
131 | } |
132 | |
133 | /* Now, take a look at the answer section, and see if it is complete. |
134 | * If it has any CNAMEs we stuff them in the answer. |
135 | */ |
136 | wantedrrs= 0; |
86e7b8d9 |
137 | cbyte= anstart; |
b9de380c |
138 | for (rri= 0; rri<ancount; rri++) { |
139 | rrstart= cbyte; |
3955725c |
140 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
141 | &rrtype,&rrclass,&rdlength,&rdstart, |
142 | &ownermatched); |
86e7b8d9 |
143 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
144 | if (rrtype == -1) goto x_truncated; |
145 | |
b9de380c |
146 | if (rrclass != DNS_CLASS_IN) { |
31144a72 |
147 | adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)", |
b9de380c |
148 | rrclass,DNS_CLASS_IN); |
149 | continue; |
150 | } |
0ba0614a |
151 | if (!ownermatched) { |
98a3f706 |
152 | if (ads->iflags & adns_if_debug) { |
31144a72 |
153 | adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s", |
828d89bd |
154 | adns__diag_domain(ads,serv,qu, &qu->vb, 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) { |
4b707d8b |
160 | if (qu->flags & adns_qf_cname_forbid) { |
161 | adns__query_fail(qu,adns_s_prohibitedcname); |
162 | return; |
163 | } else if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */ |
31144a72 |
164 | qu->cname_begin= rdstart; |
31144a72 |
165 | qu->cname_dglen= dglen; |
828d89bd |
166 | st= adns__parse_domain(ads,serv,qu, &qu->vb, |
167 | qu->flags & adns_qf_quoteok_cname ? pdf_quoteok : 0, |
31144a72 |
168 | dgram,dglen, &rdstart,rdstart+rdlength); |
3955725c |
169 | if (!qu->vb.used) goto x_truncated; |
170 | if (st) { adns__query_fail(qu,st); return; } |
171 | l= strlen(qu->vb.buf)+1; |
172 | qu->answer->cname= adns__alloc_interim(qu,l); |
ea1e31e3 |
173 | if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; } |
e062dcae |
174 | |
175 | qu->cname_dgram= adns__alloc_mine(qu,dglen); |
176 | memcpy(qu->cname_dgram,dgram,dglen); |
177 | |
3955725c |
178 | memcpy(qu->answer->cname,qu->vb.buf,l); |
86e7b8d9 |
179 | cname_here= 1; |
31144a72 |
180 | /* If we find the answer section truncated after this point we restart |
181 | * the query at the CNAME; if beforehand then we obviously have to use |
182 | * TCP. If there is no truncation we can use the whole answer if |
183 | * it contains the relevant info. |
184 | */ |
185 | } else { |
186 | adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)", |
828d89bd |
187 | adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart), |
3955725c |
188 | qu->answer->cname); |
31144a72 |
189 | } |
98a3f706 |
190 | } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) { |
b9de380c |
191 | wantedrrs++; |
192 | } else { |
31144a72 |
193 | adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype); |
b9de380c |
194 | } |
195 | } |
196 | |
e062dcae |
197 | /* We defer handling truncated responses here, in case there was a CNAME |
198 | * which we could use. |
199 | */ |
200 | if (flg_tc) goto x_truncated; |
201 | |
b9de380c |
202 | nsstart= cbyte; |
203 | |
204 | if (!wantedrrs) { |
205 | /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */ |
206 | |
207 | if (rcode == rcode_nxdomain) { |
3955725c |
208 | adns__query_fail(qu,adns_s_nxdomain); |
b9de380c |
209 | return; |
210 | } |
211 | |
212 | /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */ |
0ba0614a |
213 | foundsoa= 0; foundns= 0; |
b9de380c |
214 | for (rri= 0; rri<nscount; rri++) { |
0ba0614a |
215 | rrstart= cbyte; |
3955725c |
216 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
217 | &rrtype,&rrclass,&rdlength,&rdstart, 0); |
218 | if (st) { adns__query_fail(qu,st); return; } |
0ba0614a |
219 | if (rrtype==-1) goto x_truncated; |
220 | if (rrclass != DNS_CLASS_IN) { |
31144a72 |
221 | adns__diag(ads,serv,qu, |
222 | "ignoring authority RR with wrong class %d (expected IN=%d)", |
0ba0614a |
223 | rrclass,DNS_CLASS_IN); |
224 | continue; |
225 | } |
226 | if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; } |
227 | else if (rrtype == adns_r_ns_raw) { foundns= 1; } |
b9de380c |
228 | } |
0ba0614a |
229 | |
230 | if (foundsoa || !foundns) { |
231 | /* Aha ! A NODATA response, good. */ |
3955725c |
232 | adns__query_fail(qu,adns_s_nodata); |
0ba0614a |
233 | return; |
234 | } |
235 | |
236 | /* Now what ? No relevant answers, no SOA, and at least some NS's. |
237 | * Looks like a referral. Just one last chance ... if we came across |
31144a72 |
238 | * a CNAME in this datagram then we should probably do our own CNAME |
239 | * lookup now in the hope that we won't get a referral again. |
0ba0614a |
240 | */ |
e062dcae |
241 | if (cname_here) goto x_restartquery; |
0ba0614a |
242 | |
243 | /* Bloody hell, I thought we asked for recursion ? */ |
31144a72 |
244 | if (flg_rd) { |
245 | adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup"); |
246 | } |
0ba0614a |
247 | if (!flg_ra) { |
31144a72 |
248 | adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us"); |
3955725c |
249 | adns__query_fail(qu,adns_s_norecurse); |
31144a72 |
250 | } else { |
251 | adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral"); |
ea1e31e3 |
252 | adns__query_fail(qu,adns_s_invalidresponse); |
0ba0614a |
253 | } |
b9de380c |
254 | return; |
255 | } |
256 | |
0ba0614a |
257 | /* Now, we have some RRs which we wanted. */ |
b9de380c |
258 | |
3955725c |
259 | qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs); |
ea1e31e3 |
260 | if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nomemory); return; } |
98a3f706 |
261 | |
e062dcae |
262 | typei= qu->typei; |
98a3f706 |
263 | cbyte= anstart; |
e062dcae |
264 | rrsdata= qu->answer->rrs.bytes; |
1dfe95d8 |
265 | |
266 | pai.ads= qu->ads; |
267 | pai.qu= qu; |
268 | pai.serv= serv; |
269 | pai.dgram= dgram; |
270 | pai.dglen= dglen; |
271 | pai.nsstart= nsstart; |
272 | pai.nscount= nscount; |
273 | pai.arcount= arcount; |
7da21070 |
274 | pai.now= now; |
1dfe95d8 |
275 | |
276 | for (rri=0, nrrs=0; rri<ancount; rri++) { |
3955725c |
277 | st= adns__findrr(qu,serv, dgram,dglen,&cbyte, |
278 | &rrtype,&rrclass,&rdlength,&rdstart, |
279 | &ownermatched); |
98a3f706 |
280 | assert(!st); assert(rrtype != -1); |
281 | if (rrclass != DNS_CLASS_IN || |
31144a72 |
282 | rrtype != (qu->typei->type & adns__rrt_typemask) || |
283 | !ownermatched) |
98a3f706 |
284 | continue; |
1dfe95d8 |
285 | st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz); |
3955725c |
286 | if (st) { adns__query_fail(qu,st); return; } |
31144a72 |
287 | if (rdstart==-1) goto x_truncated; |
e062dcae |
288 | nrrs++; |
98a3f706 |
289 | } |
e062dcae |
290 | assert(nrrs==wantedrrs); |
291 | qu->answer->nrrs= nrrs; |
b9de380c |
292 | |
98a3f706 |
293 | /* This may have generated some child queries ... */ |
294 | if (qu->children.head) { |
295 | qu->state= query_child; |
296 | LIST_LINK_TAIL(ads->childw,qu); |
297 | return; |
b9de380c |
298 | } |
ec477b9e |
299 | |
3955725c |
300 | adns__query_done(qu); |
98a3f706 |
301 | return; |
0ba0614a |
302 | |
e576be50 |
303 | x_truncated: |
e062dcae |
304 | |
98a3f706 |
305 | if (!flg_tc) { |
31144a72 |
306 | adns__diag(ads,serv,qu,"server sent datagram which points outside itself"); |
ea1e31e3 |
307 | adns__query_fail(qu,adns_s_invalidresponse); |
98a3f706 |
308 | return; |
309 | } |
98a3f706 |
310 | qu->flags |= adns_qf_usevc; |
e062dcae |
311 | |
312 | x_restartquery: |
313 | |
314 | if (qu->cname_dgram) { |
315 | st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id, |
316 | qu->cname_dgram, qu->cname_dglen, qu->cname_begin, |
317 | qu->typei->type, qu->flags); |
318 | if (st) { adns__query_fail(qu,st); return; } |
319 | |
320 | newquery= realloc(qu->query_dgram,qu->vb.used); |
ea1e31e3 |
321 | if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; } |
e062dcae |
322 | |
323 | qu->query_dgram= newquery; |
324 | qu->query_dglen= qu->vb.used; |
325 | memcpy(newquery,qu->vb.buf,qu->vb.used); |
326 | } |
327 | |
328 | adns__reset_cnameonly(qu); |
3955725c |
329 | adns__query_udp(qu,now); |
98a3f706 |
330 | } |