-/**/
+/*
+ * reply.c
+ * - main handling and parsing routine for received datagrams
+ */
+/*
+ * This file is part of adns, which is Copyright (C) 1997, 1998 Ian Jackson
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
#include "internal.h"
-void adns__procdgram(adns_state ads, const byte *dgram, int len, int serv) {
- /* FIXME do something with incoming datagrams */
- adns__diag(ads,serv,"received datagram size %d",len);
+static void cname_recurse(adns_query qu, adns_queryflags xflags) {
+ abort(); /* FIXME */
+}
+
+void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
+ int serv, struct timeval now) {
+ int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns;
+ int id, f1, f2, qdcount, ancount, nscount, arcount;
+ int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
+ int rrtype, rrclass, rdlength, rdstart, ownermatched, l;
+ int anstart, nsstart, arstart;
+ adns_query qu, nqu;
+ dns_rcode rcode;
+ adns_status st;
+
+ if (dglen<DNS_HDRSIZE) {
+ adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
+ return;
+ }
+ GET_W(cbyte,id);
+ GET_B(cbyte,f1);
+ GET_B(cbyte,f2);
+ GET_W(cbyte,qdcount);
+ GET_W(cbyte,ancount);
+ GET_W(cbyte,nscount);
+ GET_W(cbyte,arcount);
+ assert(cbyte == DNS_HDRSIZE);
+
+ flg_qr= f1&0x80;
+ opcode= (f1&0x78)>>3;
+ flg_tc= f1&0x20;
+ flg_rd= f1&0x01;
+ flg_ra= f2&0x80;
+ rcode= (f1&0x0f);
+
+ if (flg_qr) {
+ adns__diag(ads,serv,0,"server sent us a query, not a response");
+ return;
+ }
+ if (opcode) {
+ adns__diag(ads,serv,0,"server sent us unknown opcode %d (wanted 0=QUERY)",opcode);
+ return;
+ }
+ if (!qdcount) {
+ adns__diag(ads,serv,0,"server sent reply without quoting our question");
+ return;
+ } else if (qdcount>1) {
+ adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
+ qdcount);
+ return;
+ }
+ for (qu= ads->timew.head; qu; qu= nqu) {
+ nqu= qu->next;
+ if (qu->id != id) continue;
+ if (dglen < qu->query_dglen) continue;
+ if (memcmp(qu->query_dgram+DNS_HDRSIZE,
+ dgram+DNS_HDRSIZE,
+ qu->query_dglen-DNS_HDRSIZE))
+ continue;
+ break;
+ }
+ anstart= qu->query_dglen;
+ if (!qu) {
+ adns__debug(ads,serv,0,"reply not found (id=%02x)",id);
+ return;
+ }
+
+ LIST_UNLINK(ads->timew,qu);
+ /* We're definitely going to do something with this query now */
+
+ switch (rcode) {
+ case rcode_noerror:
+ case rcode_nxdomain:
+ break;
+ case rcode_formaterror:
+ adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
+ adns__query_fail(qu,adns_s_serverfaulty);
+ return;
+ case rcode_servfail:
+ adns__query_fail(qu,adns_s_servfail);
+ return;
+ case rcode_notimp:
+ adns__warn(ads,serv,qu,"server claims not to implement our query");
+ adns__query_fail(qu,adns_s_notimplemented);
+ return;
+ case rcode_refused:
+ adns__warn(ads,serv,qu,"server refused our query");
+ adns__query_fail(qu,adns_s_refused);
+ return;
+ default:
+ adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
+ adns__query_fail(qu,adns_s_reasonunknown);
+ return;
+ }
+
+ /* Now, take a look at the answer section, and see if it is complete.
+ * If it has any CNAMEs we stuff them in the answer.
+ */
+ wantedrrs= 0;
+ for (rri= 0; rri<ancount; rri++) {
+ rrstart= cbyte;
+ st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
+ &rrtype,&rrclass,&rdlength,&rdstart,
+ &ownermatched);
+ if (st) adns__query_fail(qu,st);
+ if (rrtype == -1) goto x_truncated;
+
+ if (rrclass != DNS_CLASS_IN) {
+ adns__diag(ads,serv,qu,"ignoring answer RR with wrong class %d (expected IN=%d)",
+ rrclass,DNS_CLASS_IN);
+ continue;
+ }
+ if (!ownermatched) {
+ if (ads->iflags & adns_if_debug) {
+ adns__debug(ads,serv,qu,"ignoring RR with an unexpected owner %s",
+ adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
+ dgram,dglen,rrstart));
+ }
+ continue;
+ }
+ if (rrtype == adns_r_cname &&
+ (qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
+ if (!qu->cname_dgram) { /* Ignore second and subsequent CNAMEs */
+ qu->cname_dgram= adns__alloc_mine(qu,dglen);
+ if (!qu->cname_dgram) return;
+ qu->cname_begin= rdstart;
+ qu->cname_dglen= dglen;
+ st= adns__parse_domain(ads,serv,qu, &qu->vb,qu->flags,
+ dgram,dglen, &rdstart,rdstart+rdlength);
+ if (!qu->vb.used) goto x_truncated;
+ if (st) { adns__query_fail(qu,st); return; }
+ l= strlen(qu->vb.buf)+1;
+ qu->answer->cname= adns__alloc_interim(qu,l);
+ if (!qu->answer->cname) return;
+ memcpy(qu->answer->cname,qu->vb.buf,l);
+ /* If we find the answer section truncated after this point we restart
+ * the query at the CNAME; if beforehand then we obviously have to use
+ * TCP. If there is no truncation we can use the whole answer if
+ * it contains the relevant info.
+ */
+ } else {
+ adns__debug(ads,serv,qu,"ignoring duplicate CNAME (%s, as well as %s)",
+ adns__diag_domain(ads,serv,qu, &qu->vb,qu->flags,
+ dgram,dglen,rdstart),
+ qu->answer->cname);
+ }
+ } else if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
+ wantedrrs++;
+ } else {
+ adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
+ }
+ }
+
+ /* If we got here then the answer section is intact. */
+ nsstart= cbyte;
+
+ if (!wantedrrs) {
+ /* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
+
+ if (rcode == rcode_nxdomain) {
+ adns__query_fail(qu,adns_s_nxdomain);
+ return;
+ }
+
+ /* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
+ foundsoa= 0; foundns= 0;
+ for (rri= 0; rri<nscount; rri++) {
+ rrstart= cbyte;
+ st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
+ &rrtype,&rrclass,&rdlength,&rdstart, 0);
+ if (st) { adns__query_fail(qu,st); return; }
+ if (rrtype==-1) goto x_truncated;
+ if (rrclass != DNS_CLASS_IN) {
+ adns__diag(ads,serv,qu,
+ "ignoring authority RR with wrong class %d (expected IN=%d)",
+ rrclass,DNS_CLASS_IN);
+ continue;
+ }
+ if (rrtype == adns_r_soa_raw) { foundsoa= 1; break; }
+ else if (rrtype == adns_r_ns_raw) { foundns= 1; }
+ }
+
+ if (foundsoa || !foundns) {
+ /* Aha ! A NODATA response, good. */
+ adns__query_fail(qu,adns_s_nodata);
+ return;
+ }
+
+ /* Now what ? No relevant answers, no SOA, and at least some NS's.
+ * Looks like a referral. Just one last chance ... if we came across
+ * a CNAME in this datagram then we should probably do our own CNAME
+ * lookup now in the hope that we won't get a referral again.
+ */
+ if (qu->cname_dgram == dgram) { cname_recurse(qu,0); return; }
+
+ /* Bloody hell, I thought we asked for recursion ? */
+ if (flg_rd) {
+ adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
+ }
+ if (!flg_ra) {
+ adns__diag(ads,serv,qu,"server is not willing to do recursive lookups for us");
+ adns__query_fail(qu,adns_s_norecurse);
+ } else {
+ adns__diag(ads,serv,qu,"server claims to do recursion, but gave us a referral");
+ adns__query_fail(qu,adns_s_serverfaulty);
+ }
+ return;
+ }
+
+ /* Now, we have some RRs which we wanted. */
+
+ qu->answer->rrs.untyped= adns__alloc_interim(qu,qu->typei->rrsz*wantedrrs);
+ if (!qu->answer->rrs.untyped) return;
+
+ cbyte= anstart;
+ arstart= -1;
+ for (rri=0; rri<ancount; rri++) {
+ st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
+ &rrtype,&rrclass,&rdlength,&rdstart,
+ &ownermatched);
+ assert(!st); assert(rrtype != -1);
+ if (rrclass != DNS_CLASS_IN ||
+ rrtype != (qu->typei->type & adns__rrt_typemask) ||
+ !ownermatched)
+ continue;
+ assert(qu->answer->nrrs<wantedrrs);
+ st= qu->typei->parse(qu,serv,
+ dgram,dglen, rdstart,rdstart+rdlength,
+ qu->answer->rrs.bytes+qu->answer->nrrs*qu->typei->rrsz);
+ if (st) { adns__query_fail(qu,st); return; }
+ if (rdstart==-1) goto x_truncated;
+ }
+
+ /* This may have generated some child queries ... */
+ if (qu->children.head) {
+ qu->state= query_child;
+ LIST_LINK_TAIL(ads->childw,qu);
+ return;
+ }
+
+ adns__query_done(qu);
+ return;
+
+ x_truncated:
+ if (!flg_tc) {
+ adns__diag(ads,serv,qu,"server sent datagram which points outside itself");
+ adns__query_fail(qu,adns_s_serverfaulty);
+ return;
+ }
+ if (qu->cname_dgram) { cname_recurse(qu,adns_qf_usevc); return; }
+ adns__reset_cnameonly(qu);
+ qu->flags |= adns_qf_usevc;
+ adns__query_udp(qu,now);
}
~ianmdlvl / adns.git / blobdiff