/*
* 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.
*
* $Id: reply.c,v 1.2 2003/06/14 13:55:50 tr-ircd Exp $
*/
#include "struct.h"
#include "memory.h"
#include "fileio.h"
#include "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)
LIST_UNLINK(ads->tcpw, qu);
else
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 && ++qu->cname_count >= 2) {
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;
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 = (byte *) MyRealloc(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);
}
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