chiark / gitweb /
FIXMEs for multithreading and IPv6 - deferred.
[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;
f2ad23ee 36 const typeinfo *typei;
5c596e4d 37 adns_query qu, nqu;
38 dns_rcode rcode;
54ed1d64 39 adns_status st;
1e9efa71 40 vbuf tempvb;
f2ad23ee 41 byte *newquery, *rrsdata;
26eb6bdc 42 parseinfo pai;
168e26fe 43
5c596e4d 44 if (dglen<DNS_HDRSIZE) {
11c8bf9b 45 adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
168e26fe 46 return;
47 }
9a2b67d4 48 cbyte= 0;
54ed1d64 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);
5c596e4d 56 assert(cbyte == DNS_HDRSIZE);
168e26fe 57
7f702335 58 flg_qr= f1&0x80;
59 opcode= (f1&0x78)>>3;
f2ad23ee 60 flg_tc= f1&0x02;
7f702335 61 flg_rd= f1&0x01;
8312a1c2 62 flg_ra= f2&0x80;
1e9efa71 63 rcode= (f2&0x0f);
8312a1c2 64
1e9efa71 65 cname_here= 0;
66
9a2b67d4 67 if (!flg_qr) {
11c8bf9b 68 adns__diag(ads,serv,0,"server sent us a query, not a response");
168e26fe 69 return;
70 }
7f702335 71 if (opcode) {
11c8bf9b 72 adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
168e26fe 73 return;
74 }
75 if (!qdcount) {
11c8bf9b 76 adns__diag(ads,serv,0,"server sent reply without quoting our question");
168e26fe 77 return;
78 } else if (qdcount>1) {
11c8bf9b 79 adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
168e26fe 80 qdcount);
81 return;
82 }
5c596e4d 83 for (qu= ads->timew.head; qu; qu= nqu) {
168e26fe 84 nqu= qu->next;
85 if (qu->id != id) continue;
11c8bf9b 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))
54ed1d64 90 continue;
168e26fe 91 break;
92 }
93 if (!qu) {
1e9efa71 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",
cd363ffd 97 id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE));
1e9efa71 98 adns__vbuf_free(&tempvb);
99 }
168e26fe 100 return;
101 }
1e9efa71 102 anstart= qu->query_dglen;
f318f883 103 arstart= -1;
5c596e4d 104
105 LIST_UNLINK(ads->timew,qu);
106 /* We're definitely going to do something with this query now */
107
54ed1d64 108 switch (rcode) {
109 case rcode_noerror:
110 case rcode_nxdomain:
168e26fe 111 break;
54ed1d64 112 case rcode_formaterror:
7f702335 113 adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
9b86645c 114 adns__query_fail(qu,adns_s_rcodeformaterror);
168e26fe 115 return;
5c596e4d 116 case rcode_servfail:
9b86645c 117 adns__query_fail(qu,adns_s_rcodeservfail);
168e26fe 118 return;
54ed1d64 119 case rcode_notimp:
7f702335 120 adns__warn(ads,serv,qu,"server claims not to implement our query");
9b86645c 121 adns__query_fail(qu,adns_s_rcodenotimplemented);
54ed1d64 122 return;
123 case rcode_refused:
7f702335 124 adns__warn(ads,serv,qu,"server refused our query");
9b86645c 125 adns__query_fail(qu,adns_s_rcoderefused);
54ed1d64 126 return;
127 default:
7f702335 128 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
9b86645c 129 adns__query_fail(qu,adns_s_rcodeunknown);
54ed1d64 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;
1e9efa71 137 cbyte= anstart;
54ed1d64 138 for (rri= 0; rri<ancount; rri++) {
139 rrstart= cbyte;
11c8bf9b 140 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
141 &rrtype,&rrclass,&rdlength,&rdstart,
142 &ownermatched);
1e9efa71 143 if (st) { adns__query_fail(qu,st); return; }
8312a1c2 144 if (rrtype == -1) goto x_truncated;
145
54ed1d64 146 if (rrclass != DNS_CLASS_IN) {
7f702335 147 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
54ed1d64 148 rrclass,DNS_CLASS_IN);
149 continue;
150 }
8312a1c2 151 if (!ownermatched) {
5c596e4d 152 if (ads->iflags & adns_if_debug) {
7f702335 153 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
cd363ffd 154 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rrstart));
8312a1c2 155 }
54ed1d64 156 continue;
157 }
f2ad23ee 158 if (rrtype == adns_r_cname && /* fixme - implement adns_qf_nocname */
7f702335 159 (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
59fbb06a 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 */
7f702335 164 qu->cname_begin= rdstart;
7f702335 165 qu->cname_dglen= dglen;
cd363ffd 166 st= adns__parse_domain(ads,serv,qu, &qu->vb,
167 qu->flags & adns_qf_quoteok_cname ? pdf_quoteok : 0,
7f702335 168 dgram,dglen, &rdstart,rdstart+rdlength);
11c8bf9b 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);
9b86645c 173 if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; }
f2ad23ee 174
175 qu->cname_dgram= adns__alloc_mine(qu,dglen);
176 memcpy(qu->cname_dgram,dgram,dglen);
177
11c8bf9b 178 memcpy(qu->answer->cname,qu->vb.buf,l);
1e9efa71 179 cname_here= 1;
7f702335 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)",
cd363ffd 187 adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart),
11c8bf9b 188 qu->answer->cname);
7f702335 189 }
5c596e4d 190 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
54ed1d64 191 wantedrrs++;
192 } else {
7f702335 193 adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
54ed1d64 194 }
195 }
196
f2ad23ee 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
54ed1d64 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) {
11c8bf9b 208 adns__query_fail(qu,adns_s_nxdomain);
54ed1d64 209 return;
210 }
211
212 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
8312a1c2 213 foundsoa= 0; foundns= 0;
54ed1d64 214 for (rri= 0; rri<nscount; rri++) {
8312a1c2 215 rrstart= cbyte;
11c8bf9b 216 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
217 &rrtype,&rrclass,&rdlength,&rdstart, 0);
218 if (st) { adns__query_fail(qu,st); return; }
8312a1c2 219 if (rrtype==-1) goto x_truncated;
220 if (rrclass != DNS_CLASS_IN) {
7f702335 221 adns__diag(ads,serv,qu,
222 "ignoring authority RR with wrong class %d (expected IN=%d)",
8312a1c2 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; }
54ed1d64 228 }
8312a1c2 229
230 if (foundsoa || !foundns) {
231 /* Aha ! A NODATA response, good. */
11c8bf9b 232 adns__query_fail(qu,adns_s_nodata);
8312a1c2 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
7f702335 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.
8312a1c2 240 */
f2ad23ee 241 if (cname_here) goto x_restartquery;
8312a1c2 242
243 /* Bloody hell, I thought we asked for recursion ? */
7f702335 244 if (flg_rd) {
245 adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
246 }
8312a1c2 247 if (!flg_ra) {
7f702335 248 adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
11c8bf9b 249 adns__query_fail(qu,adns_s_norecurse);
7f702335 250 } else {
251 adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
9b86645c 252 adns__query_fail(qu,adns_s_invalidresponse);
8312a1c2 253 }
54ed1d64 254 return;
255 }
256
8312a1c2 257 /* Now, we have some RRs which we wanted. */
54ed1d64 258
11c8bf9b 259 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
9b86645c 260 if (!qu->answer->rrs.untyped) { adns__query_fail(qu,adns_s_nomemory); return; }
5c596e4d 261
f2ad23ee 262 typei= qu->typei;
5c596e4d 263 cbyte= anstart;
f2ad23ee 264 rrsdata= qu->answer->rrs.bytes;
26eb6bdc 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;
ba1ddf08 274 pai.now= now;
26eb6bdc 275
276 for (rri=0, nrrs=0; rri<ancount; rri++) {
11c8bf9b 277 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
278 &rrtype,&rrclass,&rdlength,&rdstart,
279 &ownermatched);
5c596e4d 280 assert(!st); assert(rrtype != -1);
281 if (rrclass != DNS_CLASS_IN ||
7f702335 282 rrtype != (qu->typei->type & adns__rrt_typemask) ||
283 !ownermatched)
5c596e4d 284 continue;
26eb6bdc 285 st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz);
11c8bf9b 286 if (st) { adns__query_fail(qu,st); return; }
7f702335 287 if (rdstart==-1) goto x_truncated;
f2ad23ee 288 nrrs++;
5c596e4d 289 }
f2ad23ee 290 assert(nrrs==wantedrrs);
291 qu->answer->nrrs= nrrs;
54ed1d64 292
5c596e4d 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;
54ed1d64 298 }
168e26fe 299
11c8bf9b 300 adns__query_done(qu);
5c596e4d 301 return;
8312a1c2 302
98db6da3 303 x_truncated:
f2ad23ee 304
5c596e4d 305 if (!flg_tc) {
7f702335 306 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
9b86645c 307 adns__query_fail(qu,adns_s_invalidresponse);
5c596e4d 308 return;
309 }
5c596e4d 310 qu->flags |= adns_qf_usevc;
f2ad23ee 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);
9b86645c 321 if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; }
f2ad23ee 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);
11c8bf9b 329 adns__query_udp(qu,now);
5c596e4d 330}