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#if !defined(lint) && !defined(SABER)
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static const char rcsid[] = "$Id: res_findzonecut.c,v 1.16 2005/03/17 20:15:18 dhankins Exp $";
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* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
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* Copyright (c) 1999-2003 by Internet Software Consortium
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
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* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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* Internet Systems Consortium, Inc.
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* Redwood City, CA 94063
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#include <sys/param.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <isc-dhcp/list.h>
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#include "minires/minires.h"
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#include "arpa/nameser.h"
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/* Data structures. */
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ISC_LINK(struct rr_a) link;
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typedef ISC_LIST(rr_a) rrset_a;
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typedef struct rr_ns {
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ISC_LINK(struct rr_ns) link;
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typedef ISC_LIST(rr_ns) rrset_ns;
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static int satisfy(res_state,
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const char *, rrset_ns *, struct in_addr *, int);
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static int add_addrs(res_state, rr_ns *, struct in_addr *, int);
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static ns_rcode get_soa(res_state, const char *, ns_class,
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char *, size_t, char *, size_t,
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static isc_result_t get_ns(res_state, const char *, ns_class, rrset_ns *);
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static isc_result_t get_glue(res_state, ns_class, rrset_ns *);
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static isc_result_t save_ns(res_state, ns_msg *, ns_sect,
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const char *, ns_class, rrset_ns *);
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static isc_result_t save_a(res_state, ns_msg *, ns_sect,
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const char *, ns_class, rrset_a *);
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static void free_nsrrset(rrset_ns *);
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static void free_nsrr(rrset_ns *, rr_ns *);
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static rr_ns * find_ns(rrset_ns *, const char *);
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static isc_result_t do_query(res_state, const char *, ns_class, ns_type,
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double *, ns_msg *, int *);
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* res_findzonecut(res, dname, class, zname, zsize, addrs, naddrs)
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* find enclosing zone for a <dname,class>, and some server addresses
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* res - resolver context to work within (is modified)
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* dname - domain name whose enclosing zone is desired
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* class - class of dname (and its enclosing zone)
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* zname - found zone name
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* zsize - allocated size of zname
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* addrs - found server addresses
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* naddrs - max number of addrs
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* < 0 - an error occurred (check errno)
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* = 0 - zname is now valid, but addrs[] wasn't changed
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* > 0 - zname is now valid, and return value is number of addrs[] found
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* this function calls res_nsend() which means it depends on correctly
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* functioning recursive nameservers (usually defined in /etc/resolv.conf
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* or its local equivilent).
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* we start by asking for an SOA<dname,class>. if we get one as an
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* answer, that just means <dname,class> is a zone top, which is fine.
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* more than likely we'll be told to go pound sand, in the form of a
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* note that we are not prepared to deal with referrals since that would
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* only come from authority servers and our correctly functioning local
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* recursive server would have followed the referral and got us something
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* if the authority section contains an SOA, this SOA should also be the
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* closest enclosing zone, since any intermediary zone cuts would've been
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* returned as referrals and dealt with by our correctly functioning local
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* recursive name server. but an SOA in the authority section should NOT
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* match our dname (since that would have been returned in the answer
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* section). an authority section SOA has to be "above" our dname.
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* we cannot fail to find an SOA in this way. ultimately we'll return
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* a zname indicating the root zone if that's the closest enclosing zone.
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* however, since authority section SOA's were once optional, it's
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* possible that we'll have to go hunting for the enclosing SOA by
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* ripping labels off the front of our dname -- this is known as "doing
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* ultimately we want some server addresses, which are ideally the ones
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* pertaining to the SOA.MNAME, but only if there is a matching NS RR.
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* so the second phase (after we find an SOA) is to go looking for the
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* NS RRset for that SOA's zone.
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* no answer section processed by this code is allowed to contain CNAME
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* or DNAME RR's. for the SOA query this means we strip a label and
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* keep going. for the NS and A queries this means we just give up.
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res_findzonecut(res_state statp, const char *dname, ns_class class, int opts,
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char *zname, size_t zsize, struct in_addr *addrs, int naddrs,
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int *count, void *zcookie)
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char mname[NS_MAXDNAME];
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DPRINTF(("START dname='%s' class=%s, zsize=%ld, naddrs=%d",
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dname, p_class(class), (long)zsize, naddrs));
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save_pfcode = statp->pfcode;
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statp->pfcode |= RES_PRF_HEAD2 | RES_PRF_HEAD1 | RES_PRF_HEADX |
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RES_PRF_QUES | RES_PRF_ANS |
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RES_PRF_AUTH | RES_PRF_ADD;
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ISC_LIST_INIT(nsrrs);
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DPRINTF (("look for a predefined zone statement"));
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rcode = find_cached_zone (dname, class, zname, zsize,
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addrs, naddrs, &n, zcookie);
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if (rcode == ISC_R_SUCCESS)
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DPRINTF(("get the soa, and see if it has enough glue"));
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if ((rcode = get_soa(statp, dname, class, zname, zsize,
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mname, sizeof mname, &nsrrs)) != ISC_R_SUCCESS ||
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((opts & RES_EXHAUSTIVE) == 0 &&
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(n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
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DPRINTF(("get the ns rrset and see if it has enough glue"));
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if ((rcode = get_ns(statp, zname, class, &nsrrs)) != ISC_R_SUCCESS ||
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((opts & RES_EXHAUSTIVE) == 0 &&
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(n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
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DPRINTF(("get the missing glue and see if it's finally enough"));
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if ((rcode = get_glue(statp, class, &nsrrs)) == ISC_R_SUCCESS)
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n = satisfy(statp, mname, &nsrrs, addrs, naddrs);
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/* If we found the zone, cache it. */
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cache_found_zone (class, zname, addrs, n);
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DPRINTF(("FINISH n=%d (%s)", n, (n < 0) ? strerror(errno) : "OK"));
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free_nsrrset(&nsrrs);
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statp->pfcode = save_pfcode;
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satisfy(res_state statp,
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const char *mname, rrset_ns *nsrrsp, struct in_addr *addrs, int naddrs)
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nsrr = find_ns(nsrrsp, mname);
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x = add_addrs(statp, nsrr, addrs, naddrs);
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for (nsrr = ISC_LIST_HEAD(*nsrrsp);
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nsrr != NULL && naddrs > 0;
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nsrr = ISC_LIST_NEXT(nsrr, link))
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if (ns_samename(nsrr->name, mname) != 1) {
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x = add_addrs(statp, nsrr, addrs, naddrs);
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DPRINTF(("satisfy(%s): %d", mname, n));
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add_addrs(res_state statp, rr_ns *nsrr, struct in_addr *addrs, int naddrs) {
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for (arr = ISC_LIST_HEAD(nsrr->addrs);
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arr != NULL; arr = ISC_LIST_NEXT(arr, link)) {
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*addrs++ = arr->addr;
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DPRINTF(("add_addrs: %d", n));
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get_soa(res_state statp, const char *dname, ns_class class,
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char *zname, size_t zsize, char *mname, size_t msize,
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char tname[NS_MAXDNAME];
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double resp[NS_PACKETSZ / sizeof (double)];
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int n, i, ancount, nscount;
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* Find closest enclosing SOA, even if it's for the root zone.
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/* First canonicalize dname (exactly one unescaped trailing "."). */
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status = ns_makecanon(dname, tname, sizeof tname);
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if (status != ISC_R_SUCCESS)
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/* Now grovel the subdomains, hunting for an SOA answer or auth. */
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/* Leading or inter-label '.' are skipped here. */
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while (*dname == '.')
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/* Is there an SOA? */
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rcode = do_query(statp, dname, class, ns_t_soa,
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if (rcode != ISC_R_SUCCESS) {
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DPRINTF(("get_soa: do_query('%s', %s) failed (%d)",
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dname, p_class(class), n));
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DPRINTF(("get_soa: CNAME or DNAME found"));
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sect = ns_s_max, n = 0;
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ancount = ns_msg_count(msg, ns_s_an);
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nscount = ns_msg_count(msg, ns_s_ns);
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if (ancount > 0 && rcode == ISC_R_SUCCESS)
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sect = ns_s_an, n = ancount;
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else if (nscount > 0)
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sect = ns_s_ns, n = nscount;
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sect = ns_s_max, n = 0;
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for (i = 0; i < n; i++) {
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rcode = ns_parserr(&msg, sect, i, &rr) < 0;
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if (rcode != ISC_R_SUCCESS) {
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DPRINTF(("get_soa: ns_parserr(%s, %d) failed",
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p_section(sect, ns_o_query), i));
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if (ns_rr_type(rr) == ns_t_cname ||
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ns_rr_type(rr) == ns_t_dname)
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if (ns_rr_type(rr) != ns_t_soa ||
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ns_rr_class(rr) != class)
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if (ns_samedomain(dname, t) == 0) {
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DPRINTF(("get_soa: %s'%s', '%s') == 0",
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"ns_samedomain(", dname, t));
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return ISC_R_NOTZONE;
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if (ns_samename(dname, t) == 1 ||
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ns_samedomain(dname, t) == 0) {
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DPRINTF(("get_soa: %smain('%s', '%s')",
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"ns_samename() || !ns_samedo",
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return ISC_R_NOTZONE;
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if (strlen(t) + 1 > zsize) {
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DPRINTF(("get_soa: zname(%d) too small (%d)",
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zsize, strlen(t) + 1));
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return ISC_R_NOSPACE;
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rdata = ns_rr_rdata(rr);
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rdlen = ns_rr_rdlen(rr);
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if (ns_name_uncompress((u_char *)resp,
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ns_msg_end(msg), rdata,
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DPRINTF(("get_soa: %s failed",
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"ns_name_uncompress"));
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return ISC_R_NOMEMORY;
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rcode = save_ns(statp, &msg,
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ns_s_ns, zname, class, nsrrsp);
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if (rcode != ISC_R_SUCCESS) {
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DPRINTF(("get_soa: save_ns failed"));
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return ISC_R_SUCCESS;
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/* If we're out of labels, then not even "." has an SOA! */
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/* Find label-terminating "."; top of loop will skip it. */
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while (*dname != '.') {
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if (*++dname == '\0') {
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return ISC_R_NOSPACE;
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DPRINTF(("get_soa: out of labels"));
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return ISC_R_DESTADDRREQ;
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get_ns(res_state statp, const char *zname, ns_class class, rrset_ns *nsrrsp) {
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double resp[NS_PACKETSZ / sizeof (double)];
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/* Go and get the NS RRs for this zone. */
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rcode = do_query(statp, zname, class, ns_t_ns, resp, &msg, &n);
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if (rcode != ISC_R_SUCCESS) {
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DPRINTF(("get_ns: do_query('zname', %s) failed (%d)",
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zname, p_class(class), rcode));
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/* Remember the NS RRs and associated A RRs that came back. */
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rcode = save_ns(statp, &msg, ns_s_an, zname, class, nsrrsp);
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if (rcode != ISC_R_SUCCESS) {
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DPRINTF(("get_ns save_ns('%s', %s) failed",
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zname, p_class(class)));
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return ISC_R_SUCCESS;
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get_glue(res_state statp, ns_class class, rrset_ns *nsrrsp) {
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rr_ns *nsrr, *nsrr_n;
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/* Go and get the A RRs for each empty NS RR on our list. */
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for (nsrr = ISC_LIST_HEAD(*nsrrsp); nsrr != NULL; nsrr = nsrr_n) {
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double resp[NS_PACKETSZ / sizeof (double)];
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nsrr_n = ISC_LIST_NEXT(nsrr, link);
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if (ISC_LIST_EMPTY(nsrr->addrs)) {
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rcode = do_query(statp, nsrr->name, class, ns_t_a,
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if (rcode != ISC_R_SUCCESS) {
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DPRINTF(("get_glue: do_query('%s', %s') failed",
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nsrr->name, p_class(class)));
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"get_glue: do_query('%s', %s') CNAME or DNAME found",
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nsrr->name, p_class(class)));
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rcode = save_a(statp, &msg, ns_s_an, nsrr->name, class,
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if (rcode != ISC_R_SUCCESS) {
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DPRINTF(("get_glue: save_r('%s', %s) failed",
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nsrr->name, p_class(class)));
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/* If it's still empty, it's just chaff. */
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if (ISC_LIST_EMPTY(nsrr->addrs)) {
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DPRINTF(("get_glue: removing empty '%s' NS",
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free_nsrr(nsrrsp, nsrr);
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return ISC_R_SUCCESS;
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save_ns(res_state statp, ns_msg *msg, ns_sect sect,
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const char *owner, ns_class class,
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for (i = 0; i < ns_msg_count(*msg, sect); i++) {
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char tname[MAXDNAME];
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rcode = ns_parserr(msg, sect, i, &rr);
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if (rcode != ISC_R_SUCCESS) {
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DPRINTF(("save_ns: ns_parserr(%s, %d) failed",
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p_section(sect, ns_o_query), i));
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if (ns_rr_type(rr) != ns_t_ns ||
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ns_rr_class(rr) != class ||
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ns_samename(ns_rr_name(rr), owner) != 1)
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nsrr = find_ns(nsrrsp, ns_rr_name(rr));
470
nsrr = malloc(sizeof *nsrr);
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DPRINTF(("save_ns: malloc failed"));
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return ISC_R_NOMEMORY;
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rdata = ns_rr_rdata(rr);
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rdlen = ns_rr_rdlen(rr);
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if (ns_name_uncompress(ns_msg_base(*msg),
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ns_msg_end(*msg), rdata,
479
tname, sizeof tname) < 0) {
480
DPRINTF(("save_ns: ns_name_uncompress failed"));
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return ISC_R_NOMEMORY;
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nsrr->name = strdup(tname);
485
if (nsrr->name == NULL) {
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DPRINTF(("save_ns: strdup failed"));
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return ISC_R_NOMEMORY;
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ISC_LIST_INIT(nsrr->addrs);
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ISC_LIST_APPEND(*nsrrsp, nsrr, link);
493
rcode = save_a(statp, msg, ns_s_ar,
494
nsrr->name, class, &nsrr->addrs);
495
if (rcode != ISC_R_SUCCESS) {
496
DPRINTF(("save_ns: save_r('%s', %s) failed",
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nsrr->name, p_class(class)));
501
return ISC_R_SUCCESS;
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save_a(res_state statp, ns_msg *msg, ns_sect sect,
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const char *owner, ns_class class,
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for (i = 0; i < ns_msg_count(*msg, sect); i++) {
516
rcode = ns_parserr(msg, sect, i, &rr);
517
if (rcode != ISC_R_SUCCESS) {
518
DPRINTF(("save_a: ns_parserr(%s, %d) failed",
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p_section(sect, ns_o_query), i));
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if (ns_rr_type(rr) != ns_t_a ||
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ns_rr_class(rr) != class ||
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ns_samename(ns_rr_name(rr), owner) != 1 ||
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ns_rr_rdlen(rr) != NS_INADDRSZ)
527
arr = malloc(sizeof *arr);
529
DPRINTF(("save_a: malloc failed"));
530
return ISC_R_NOMEMORY;
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memcpy(&arr->addr, ns_rr_rdata(rr), NS_INADDRSZ);
533
ISC_LIST_APPEND(*arrsp, arr, link);
535
return ISC_R_SUCCESS;
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free_nsrrset(rrset_ns *nsrrsp) {
542
while ((nsrr = ISC_LIST_HEAD(*nsrrsp)) != NULL)
543
free_nsrr(nsrrsp, nsrr);
547
free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) {
550
while ((arr = ISC_LIST_HEAD(nsrr->addrs)) != NULL) {
551
ISC_LIST_UNLINK(nsrr->addrs, arr, link);
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free((char *)nsrr->name);
555
ISC_LIST_UNLINK(*nsrrsp, nsrr, link);
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find_ns(rrset_ns *nsrrsp, const char *dname) {
563
for (nsrr = ISC_LIST_HEAD(*nsrrsp);
564
nsrr != NULL; nsrr = ISC_LIST_NEXT(nsrr, link))
565
if (ns_samename(nsrr->name, dname) == 1)
571
do_query(res_state statp, const char *dname, ns_class class, ns_type qtype,
572
double *resp, ns_msg *msg, int *alias_count)
574
double req[NS_PACKETSZ / sizeof (double)];
579
status = res_nmkquery(statp, ns_o_query, dname, class, qtype,
580
NULL, 0, NULL, req, NS_PACKETSZ, &n);
581
if (status != ISC_R_SUCCESS) {
582
DPRINTF(("do_query: res_nmkquery failed"));
585
status = res_nsend(statp, req, n, resp, NS_PACKETSZ, &n);
586
if (status != ISC_R_SUCCESS) {
587
DPRINTF(("do_query: res_nsend failed"));
591
DPRINTF(("do_query: res_nsend returned 0"));
592
return ISC_R_NOTFOUND;
594
if (ns_initparse((u_char *)resp, n, msg) < 0) {
595
DPRINTF(("do_query: ns_initparse failed"));
596
return ISC_R_NOSPACE;
599
for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) {
602
status = ns_parserr(msg, ns_s_an, i, &rr);
603
if (status != ISC_R_SUCCESS) {
604
DPRINTF(("do_query: ns_parserr failed"));
607
n += (ns_rr_class(rr) == class &&
608
(ns_rr_type(rr) == ns_t_cname ||
609
ns_rr_type(rr) == ns_t_dname));
613
return ISC_R_SUCCESS;
added
removed
minires/res_findzonecut.c
