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[adns] / src / reply.c
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98db6da3 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 */
d05cc330 22
23#include "internal.h"
24
11c8bf9b 25static void cname_recurse(adns_query qu, adns_queryflags xflags) {
5c596e4d 26 abort(); /* FIXME */
54ed1d64 27}
28
5c596e4d 29void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
30 int serv, struct timeval now) {
31 int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns;
11c8bf9b 32 int id, f1, f2, qdcount, ancount, nscount, arcount;
33 int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
34 int rrtype, rrclass, rdlength, rdstart, ownermatched, l;
5c596e4d 35 int anstart, nsstart, arstart;
5c596e4d 36 adns_query qu, nqu;
37 dns_rcode rcode;
54ed1d64 38 adns_status st;
168e26fe 39
5c596e4d 40 if (dglen<DNS_HDRSIZE) {
11c8bf9b 41 adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
168e26fe 42 return;
43 }
54ed1d64 44 GET_W(cbyte,id);
45 GET_B(cbyte,f1);
46 GET_B(cbyte,f2);
47 GET_W(cbyte,qdcount);
48 GET_W(cbyte,ancount);
49 GET_W(cbyte,nscount);
50 GET_W(cbyte,arcount);
5c596e4d 51 assert(cbyte == DNS_HDRSIZE);
168e26fe 52
7f702335 53 flg_qr= f1&0x80;
54 opcode= (f1&0x78)>>3;
5c596e4d 55 flg_tc= f1&0x20;
7f702335 56 flg_rd= f1&0x01;
8312a1c2 57 flg_ra= f2&0x80;
7f702335 58 rcode= (f1&0x0f);
8312a1c2 59
7f702335 60 if (flg_qr) {
11c8bf9b 61 adns__diag(ads,serv,0,"server sent us a query, not a response");
168e26fe 62 return;
63 }
7f702335 64 if (opcode) {
11c8bf9b 65 adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
168e26fe 66 return;
67 }
68 if (!qdcount) {
11c8bf9b 69 adns__diag(ads,serv,0,"server sent reply without quoting our question");
168e26fe 70 return;
71 } else if (qdcount>1) {
11c8bf9b 72 adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
168e26fe 73 qdcount);
74 return;
75 }
5c596e4d 76 for (qu= ads->timew.head; qu; qu= nqu) {
168e26fe 77 nqu= qu->next;
78 if (qu->id != id) continue;
11c8bf9b 79 if (dglen < qu->query_dglen) continue;
80 if (memcmp(qu->query_dgram+DNS_HDRSIZE,
81 dgram+DNS_HDRSIZE,
82 qu->query_dglen-DNS_HDRSIZE))
54ed1d64 83 continue;
168e26fe 84 break;
85 }
11c8bf9b 86 anstart= qu->query_dglen;
168e26fe 87 if (!qu) {
11c8bf9b 88 adns__debug(ads,serv,0,"reply not found (id=%02x)",id);
168e26fe 89 return;
90 }
5c596e4d 91
92 LIST_UNLINK(ads->timew,qu);
93 /* We're definitely going to do something with this query now */
94
54ed1d64 95 switch (rcode) {
96 case rcode_noerror:
97 case rcode_nxdomain:
168e26fe 98 break;
54ed1d64 99 case rcode_formaterror:
7f702335 100 adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
11c8bf9b 101 adns__query_fail(qu,adns_s_serverfaulty);
168e26fe 102 return;
5c596e4d 103 case rcode_servfail:
11c8bf9b 104 adns__query_fail(qu,adns_s_servfail);
168e26fe 105 return;
54ed1d64 106 case rcode_notimp:
7f702335 107 adns__warn(ads,serv,qu,"server claims not to implement our query");
11c8bf9b 108 adns__query_fail(qu,adns_s_notimplemented);
54ed1d64 109 return;
110 case rcode_refused:
7f702335 111 adns__warn(ads,serv,qu,"server refused our query");
11c8bf9b 112 adns__query_fail(qu,adns_s_refused);
54ed1d64 113 return;
114 default:
7f702335 115 adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
11c8bf9b 116 adns__query_fail(qu,adns_s_reasonunknown);
54ed1d64 117 return;
118 }
119
120 /* Now, take a look at the answer section, and see if it is complete.
121 * If it has any CNAMEs we stuff them in the answer.
122 */
123 wantedrrs= 0;
124 for (rri= 0; rri<ancount; rri++) {
125 rrstart= cbyte;
11c8bf9b 126 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
127 &rrtype,&rrclass,&rdlength,&rdstart,
128 &ownermatched);
129 if (st) adns__query_fail(qu,st);
8312a1c2 130 if (rrtype == -1) goto x_truncated;
131
54ed1d64 132 if (rrclass != DNS_CLASS_IN) {
7f702335 133 adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
54ed1d64 134 rrclass,DNS_CLASS_IN);
135 continue;
136 }
8312a1c2 137 if (!ownermatched) {
5c596e4d 138 if (ads->iflags & adns_if_debug) {
7f702335 139 adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
11c8bf9b 140 adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
141 dgram,dglen,rrstart));
8312a1c2 142 }
54ed1d64 143 continue;
144 }
7f702335 145 if (rrtype == adns_r_cname &&
146 (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
11c8bf9b 147 if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */
148 qu->cname_dgram= adns__alloc_mine(qu,dglen);
149 if (!qu->cname_dgram) return;
7f702335 150 qu->cname_begin= rdstart;
7f702335 151 qu->cname_dglen= dglen;
11c8bf9b 152 st= adns__parse_domain(ads,serv,qu, &qu->vb,qu->flags,
7f702335 153 dgram,dglen, &rdstart,rdstart+rdlength);
11c8bf9b 154 if (!qu->vb.used) goto x_truncated;
155 if (st) { adns__query_fail(qu,st); return; }
156 l= strlen(qu->vb.buf)+1;
157 qu->answer->cname= adns__alloc_interim(qu,l);
965c9782 158 if (!qu->answer->cname) return;
11c8bf9b 159 memcpy(qu->answer->cname,qu->vb.buf,l);
7f702335 160 /* If we find the answer section truncated after this point we restart
161 * the query at the CNAME; if beforehand then we obviously have to use
162 * TCP. If there is no truncation we can use the whole answer if
163 * it contains the relevant info.
164 */
165 } else {
166 adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
11c8bf9b 167 adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
168 dgram,dglen,rdstart),
169 qu->answer->cname);
7f702335 170 }
5c596e4d 171 } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
54ed1d64 172 wantedrrs++;
173 } else {
7f702335 174 adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
54ed1d64 175 }
176 }
177
178 /* If we got here then the answer section is intact. */
179 nsstart= cbyte;
180
181 if (!wantedrrs) {
182 /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
183
184 if (rcode == rcode_nxdomain) {
11c8bf9b 185 adns__query_fail(qu,adns_s_nxdomain);
54ed1d64 186 return;
187 }
188
189 /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
8312a1c2 190 foundsoa= 0; foundns= 0;
54ed1d64 191 for (rri= 0; rri<nscount; rri++) {
8312a1c2 192 rrstart= cbyte;
11c8bf9b 193 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
194 &rrtype,&rrclass,&rdlength,&rdstart, 0);
195 if (st) { adns__query_fail(qu,st); return; }
8312a1c2 196 if (rrtype==-1) goto x_truncated;
197 if (rrclass != DNS_CLASS_IN) {
7f702335 198 adns__diag(ads,serv,qu,
199 "ignoring authority RR with wrong class %d (expected IN=%d)",
8312a1c2 200 rrclass,DNS_CLASS_IN);
201 continue;
202 }
203 if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; }
204 else if (rrtype == adns_r_ns_raw) { foundns= 1; }
54ed1d64 205 }
8312a1c2 206
207 if (foundsoa || !foundns) {
208 /* Aha ! A NODATA response, good. */
11c8bf9b 209 adns__query_fail(qu,adns_s_nodata);
8312a1c2 210 return;
211 }
212
213 /* Now what ? No relevant answers, no SOA, and at least some NS's.
214 * Looks like a referral. Just one last chance ... if we came across
7f702335 215 * a CNAME in this datagram then we should probably do our own CNAME
216 * lookup now in the hope that we won't get a referral again.
8312a1c2 217 */
11c8bf9b 218 if (qu->cname_dgram == dgram) { cname_recurse(qu,0); return; }
8312a1c2 219
220 /* Bloody hell, I thought we asked for recursion ? */
7f702335 221 if (flg_rd) {
222 adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
223 }
8312a1c2 224 if (!flg_ra) {
7f702335 225 adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
11c8bf9b 226 adns__query_fail(qu,adns_s_norecurse);
7f702335 227 } else {
228 adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
11c8bf9b 229 adns__query_fail(qu,adns_s_serverfaulty);
8312a1c2 230 }
54ed1d64 231 return;
232 }
233
8312a1c2 234 /* Now, we have some RRs which we wanted. */
54ed1d64 235
11c8bf9b 236 qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
237 if (!qu->answer->rrs.untyped) return;
5c596e4d 238
239 cbyte= anstart;
5c596e4d 240 arstart= -1;
241 for (rri=0; rri<ancount; rri++) {
11c8bf9b 242 st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
243 &rrtype,&rrclass,&rdlength,&rdstart,
244 &ownermatched);
5c596e4d 245 assert(!st); assert(rrtype != -1);
246 if (rrclass != DNS_CLASS_IN ||
7f702335 247 rrtype != (qu->typei->type & adns__rrt_typemask) ||
248 !ownermatched)
5c596e4d 249 continue;
11c8bf9b 250 assert(qu->answer->nrrs<wantedrrs);
251 st= qu->typei->parse(qu,serv,
252 dgram,dglen, rdstart,rdstart+rdlength,
253 qu->answer->rrs.bytes+qu->answer->nrrs*qu->typei->rrsz);
254 if (st) { adns__query_fail(qu,st); return; }
7f702335 255 if (rdstart==-1) goto x_truncated;
5c596e4d 256 }
54ed1d64 257
5c596e4d 258 /* This may have generated some child queries ... */
259 if (qu->children.head) {
260 qu->state= query_child;
261 LIST_LINK_TAIL(ads->childw,qu);
262 return;
54ed1d64 263 }
168e26fe 264
11c8bf9b 265 adns__query_done(qu);
5c596e4d 266 return;
8312a1c2 267
98db6da3 268 x_truncated:
5c596e4d 269 if (!flg_tc) {
7f702335 270 adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
11c8bf9b 271 adns__query_fail(qu,adns_s_serverfaulty);
5c596e4d 272 return;
273 }
11c8bf9b 274 if (qu->cname_dgram) { cname_recurse(qu,adns_qf_usevc); return; }
275 adns__reset_cnameonly(qu);
5c596e4d 276 qu->flags |= adns_qf_usevc;
11c8bf9b 277 adns__query_udp(qu,now);
5c596e4d 278}