chiark / gitweb /
Restarting a TCP-using query doesn't abort.
[adns] / src / reply.c
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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 28void 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;
1be24aef 173 qu->answer->cname= adns__alloc_preserved(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 }
11c8bf9b 310 adns__query_done(qu);
5c596e4d 311 return;
8312a1c2 312
98db6da3 313 x_truncated:
f2ad23ee 314
5c596e4d 315 if (!flg_tc) {
7f702335 316 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
9b86645c 317 adns__query_fail(qu,adns_s_invalidresponse);
5c596e4d 318 return;
319 }
5c596e4d 320 qu->flags |= adns_qf_usevc;
f2ad23ee 321
322 x_restartquery:
f2ad23ee 323 if (qu->cname_dgram) {
324 st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id,
325 qu->cname_dgram, qu->cname_dglen, qu->cname_begin,
326 qu->typei->type, qu->flags);
327 if (st) { adns__query_fail(qu,st); return; }
328
329 newquery= realloc(qu->query_dgram,qu->vb.used);
9b86645c 330 if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; }
f2ad23ee 331
332 qu->query_dgram= newquery;
333 qu->query_dglen= qu->vb.used;
334 memcpy(newquery,qu->vb.buf,qu->vb.used);
335 }
336
24d52b13 337 if (qu->state == query_tcpsent) qu->state= query_tosend;
1be24aef 338 adns__reset_preserved(qu);
24d52b13 339 adns__query_send(qu,now);
5c596e4d 340}