ossp-pkg/adns/adns_reply.c
1.7
/*
* reply.c
* - main handling and parsing routine for received datagrams
*/
/*
* This file is
* Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
*
* It is part of adns, which is
* Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
* Copyright (C) 1999-2000 Tony Finch <dot@dotat.at>
*
* 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 <stdlib.h>
#include "adns_internal.h"
void adns__procdgram(adns_state ads, const byte *dgram, int dglen,
int serv, int viatcp, struct timeval now) {
int cbyte, rrstart, wantedrrs, rri, foundsoa, foundns, cname_here;
int id, f1, f2, qdcount, ancount, nscount, arcount;
int flg_ra, flg_rd, flg_tc, flg_qr, opcode;
int rrtype, rrclass, rdlength, rdstart;
int anstart, nsstart, arstart;
int ownermatched, l, nrrs;
unsigned long ttl, soattl;
const typeinfo *typei;
adns_query qu, nqu;
dns_rcode rcode;
adns_status st;
vbuf tempvb;
byte *newquery, *rrsdata;
parseinfo pai;
if (dglen<DNS_HDRSIZE) {
adns__diag(ads,serv,0,"received datagram too short for message header (%d)",dglen);
return;
}
cbyte= 0;
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&0x02;
flg_rd= f1&0x01;
flg_ra= f2&0x80;
rcode= (f2&0x0f);
cname_here= 0;
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;
}
qu= 0;
/* See if we can find the relevant query, or leave qu=0 otherwise ... */
if (qdcount == 1) {
for (qu= viatcp ? ads->tcpw.head : ads->udpw.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;
if (viatcp) {
assert(qu->state == query_tcpw);
} else {
assert(qu->state == query_tosend);
if (!(qu->udpsent & (1<<serv))) continue;
}
break;
}
if (qu) {
/* We're definitely going to do something with this query now */
if (viatcp) ADNS_LIST_UNLINK(ads->tcpw,qu);
else ADNS_LIST_UNLINK(ads->udpw,qu);
}
}
/* If we're going to ignore the packet, we return as soon as we have
* failed the query (if any) and printed the warning message (if
* any).
*/
switch (rcode) {
case rcode_noerror:
case rcode_nxdomain:
break;
case rcode_formaterror:
adns__warn(ads,serv,qu,"server cannot understand our query (Format Error)");
if (qu) adns__query_fail(qu,adns_s_rcodeformaterror);
return;
case rcode_servfail:
if (qu) adns__query_fail(qu,adns_s_rcodeservfail);
else adns__debug(ads,serv,qu,"server failure on unidentifiable query");
return;
case rcode_notimp:
adns__warn(ads,serv,qu,"server claims not to implement our query");
if (qu) adns__query_fail(qu,adns_s_rcodenotimplemented);
return;
case rcode_refused:
adns__debug(ads,serv,qu,"server refused our query");
if (qu) adns__query_fail(qu,adns_s_rcoderefused);
return;
default:
adns__warn(ads,serv,qu,"server gave unknown response code %d",rcode);
if (qu) adns__query_fail(qu,adns_s_rcodeunknown);
return;
}
if (!qu) {
if (!qdcount) {
adns__diag(ads,serv,0,"server sent reply without quoting our question");
} else if (qdcount>1) {
adns__diag(ads,serv,0,"server claimed to answer %d questions with one message",
qdcount);
} else if (ads->iflags & adns_if_debug) {
adns__vbuf_init(&tempvb);
adns__debug(ads,serv,0,"reply not found, id %02x, query owner %s",
id, adns__diag_domain(ads,serv,0,&tempvb,dgram,dglen,DNS_HDRSIZE));
adns__vbuf_free(&tempvb);
}
return;
}
/* We're definitely going to do something with this packet and this query now. */
anstart= qu->query_dglen;
arstart= -1;
/* 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;
cbyte= anstart;
for (rri= 0; rri<ancount; rri++) {
rrstart= cbyte;
st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
&rrtype,&rrclass,&ttl, &rdlength,&rdstart,
&ownermatched);
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 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, dgram,dglen,rrstart));
}
continue;
}
if (rrtype == adns_r_cname &&
(qu->typei->type & adns__rrt_typemask) != adns_r_cname) {
if (qu->flags & adns_qf_cname_forbid) {
adns__query_fail(qu,adns_s_prohibitedcname);
return;
} else if (qu->cname_dgram) { /* Ignore second and subsequent CNAME(s) */
adns__debug(ads,serv,qu,"allegedly canonical name %s is actually alias for %s",
qu->answer->cname,
adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart));
adns__query_fail(qu,adns_s_prohibitedcname);
return;
} else if (wantedrrs) { /* Ignore CNAME(s) after RR(s). */
adns__debug(ads,serv,qu,"ignoring CNAME (to %s) coexisting with RR",
adns__diag_domain(ads,serv,qu, &qu->vb, dgram,dglen,rdstart));
} else {
qu->cname_begin= rdstart;
qu->cname_dglen= dglen;
st= adns__parse_domain(ads,serv,qu, &qu->vb,
qu->flags & adns_qf_quotefail_cname ? 0 : pdf_quoteok,
dgram,dglen, &rdstart,rdstart+rdlength);
if (!qu->vb.used) goto x_truncated;
if (st) { adns__query_fail(qu,st); return; }
l= strlen((char *)qu->vb.buf)+1;
qu->answer->cname= adns__alloc_preserved(qu,l);
if (!qu->answer->cname) { adns__query_fail(qu,adns_s_nomemory); return; }
qu->cname_dgram= adns__alloc_mine(qu,dglen);
memcpy(qu->cname_dgram,dgram,dglen);
memcpy(qu->answer->cname,qu->vb.buf,l);
cname_here= 1;
adns__update_expires(qu,ttl,now);
/* 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 if (rrtype == (qu->typei->type & adns__rrt_typemask)) {
wantedrrs++;
} else {
adns__debug(ads,serv,qu,"ignoring answer RR with irrelevant type %d",rrtype);
}
}
/* We defer handling truncated responses here, in case there was a CNAME
* which we could use.
*/
if (flg_tc) goto x_truncated;
nsstart= cbyte;
if (!wantedrrs) {
/* Oops, NODATA or NXDOMAIN or perhaps a referral (which would be a problem) */
/* RFC2308: NODATA has _either_ a SOA _or_ _no_ NS records in authority section */
foundsoa= 0; soattl= 0; foundns= 0;
for (rri= 0; rri<nscount; rri++) {
rrstart= cbyte;
st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
&rrtype,&rrclass,&ttl, &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; soattl= ttl; break; }
else if (rrtype == adns_r_ns_raw) { foundns= 1; }
}
if (rcode == rcode_nxdomain) {
/* We still wanted to look for the SOA so we could find the TTL. */
adns__update_expires(qu,soattl,now);
if (qu->flags & adns_qf_search) {
adns__search_next(ads,qu,now);
} else {
adns__query_fail(qu,adns_s_nxdomain);
}
return;
}
if (foundsoa || !foundns) {
/* Aha ! A NODATA response, good. */
adns__update_expires(qu,soattl,now);
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 (cname_here) goto x_restartquery;
/* Bloody hell, I thought we asked for recursion ? */
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 {
if (!flg_rd)
adns__diag(ads,serv,qu,"server thinks we didn't ask for recursive lookup");
else
adns__debug(ads,serv,qu,"server claims to do recursion, but gave us a referral");
adns__query_fail(qu,adns_s_invalidresponse);
}
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) { adns__query_fail(qu,adns_s_nomemory); return; }
typei= qu->typei;
cbyte= anstart;
rrsdata= qu->answer->rrs.bytes;
pai.ads= qu->ads;
pai.qu= qu;
pai.serv= serv;
pai.dgram= dgram;
pai.dglen= dglen;
pai.nsstart= nsstart;
pai.nscount= nscount;
pai.arcount= arcount;
pai.now= now;
for (rri=0, nrrs=0; rri<ancount; rri++) {
st= adns__findrr(qu,serv, dgram,dglen,&cbyte,
&rrtype,&rrclass,&ttl, &rdlength,&rdstart,
&ownermatched);
assert(!st); assert(rrtype != -1);
if (rrclass != DNS_CLASS_IN ||
rrtype != (qu->typei->type & adns__rrt_typemask) ||
!ownermatched)
continue;
adns__update_expires(qu,ttl,now);
st= typei->parse(&pai, rdstart,rdstart+rdlength, rrsdata+nrrs*typei->rrsz);
if (st) { adns__query_fail(qu,st); return; }
if (rdstart==-1) goto x_truncated;
nrrs++;
}
assert(nrrs==wantedrrs);
qu->answer->nrrs= nrrs;
/* This may have generated some child queries ... */
if (qu->children.head) {
qu->state= query_childw;
ADNS_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_invalidresponse);
return;
}
qu->flags |= adns_qf_usevc;
x_restartquery:
if (qu->cname_dgram) {
st= adns__mkquery_frdgram(qu->ads,&qu->vb,&qu->id,
qu->cname_dgram, qu->cname_dglen, qu->cname_begin,
qu->typei->type, qu->flags);
if (st) { adns__query_fail(qu,st); return; }
newquery= realloc(qu->query_dgram,qu->vb.used);
if (!newquery) { adns__query_fail(qu,adns_s_nomemory); return; }
qu->query_dgram= newquery;
qu->query_dglen= qu->vb.used;
memcpy(newquery,qu->vb.buf,qu->vb.used);
}
if (qu->state == query_tcpw) qu->state= query_tosend;
qu->retries= 0;
adns__reset_preserved(qu);
adns__query_send(qu,now);
}
