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NetBSD/dist/dhcp/minires/res_findzonecut.c

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#if !defined(lint) && !defined(SABER)
static const char rcsid[] = "$Id: res_findzonecut.c,v 1.5 2005/08/11 17:13:26 drochner Exp $";
#endif /* not lint */
/*
* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 1999-2003 by Internet Software Consortium
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Internet Systems Consortium, Inc.
* 950 Charter Street
* Redwood City, CA 94063
* <info@isc.org>
* http://www.isc.org/
*/
/* Import. */
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <limits.h>
#include <netdb.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <isc-dhcp/list.h>
#include "minires/minires.h"
#include "arpa/nameser.h"
/* Data structures. */
typedef struct rr_a {
ISC_LINK(struct rr_a) link;
struct in_addr addr;
} rr_a;
typedef ISC_LIST(rr_a) rrset_a;
typedef struct rr_ns {
ISC_LINK(struct rr_ns) link;
char *name;
rrset_a addrs;
} rr_ns;
typedef ISC_LIST(rr_ns) rrset_ns;
/* Forward. */
static int satisfy(res_state,
const char *, rrset_ns *, struct in_addr *, int);
static int add_addrs(res_state, rr_ns *, struct in_addr *, int);
static ns_rcode get_soa(res_state, const char *, ns_class,
char *, size_t, char *, size_t,
rrset_ns *);
static isc_result_t get_ns(res_state, const char *, ns_class, rrset_ns *);
static isc_result_t get_glue(res_state, ns_class, rrset_ns *);
static isc_result_t save_ns(res_state, ns_msg *, ns_sect,
const char *, ns_class, rrset_ns *);
static isc_result_t save_a(res_state, ns_msg *, ns_sect,
const char *, ns_class, rrset_a *);
static void free_nsrrset(rrset_ns *);
static void free_nsrr(rrset_ns *, rr_ns *);
static rr_ns * find_ns(rrset_ns *, const char *);
static isc_result_t do_query(res_state, const char *, ns_class, ns_type,
double *, ns_msg *, int *);
/* Public. */
/*
* int
* res_findzonecut(res, dname, class, zname, zsize, addrs, naddrs)
* find enclosing zone for a <dname,class>, and some server addresses
* parameters:
* res - resolver context to work within (is modified)
* dname - domain name whose enclosing zone is desired
* class - class of dname (and its enclosing zone)
* zname - found zone name
* zsize - allocated size of zname
* addrs - found server addresses
* naddrs - max number of addrs
* return values:
* < 0 - an error occurred (check errno)
* = 0 - zname is now valid, but addrs[] wasn't changed
* > 0 - zname is now valid, and return value is number of addrs[] found
* notes:
* this function calls res_nsend() which means it depends on correctly
* functioning recursive nameservers (usually defined in /etc/resolv.conf
* or its local equivilent).
*
* we start by asking for an SOA<dname,class>. if we get one as an
* answer, that just means <dname,class> is a zone top, which is fine.
* more than likely we'll be told to go pound sand, in the form of a
* negative answer.
*
* note that we are not prepared to deal with referrals since that would
* only come from authority servers and our correctly functioning local
* recursive server would have followed the referral and got us something
* more definite.
*
* if the authority section contains an SOA, this SOA should also be the
* closest enclosing zone, since any intermediary zone cuts would've been
* returned as referrals and dealt with by our correctly functioning local
* recursive name server. but an SOA in the authority section should NOT
* match our dname (since that would have been returned in the answer
* section). an authority section SOA has to be "above" our dname.
*
* we cannot fail to find an SOA in this way. ultimately we'll return
* a zname indicating the root zone if that's the closest enclosing zone.
* however, since authority section SOA's were once optional, it's
* possible that we'll have to go hunting for the enclosing SOA by
* ripping labels off the front of our dname -- this is known as "doing
* it the hard way."
*
* ultimately we want some server addresses, which are ideally the ones
* pertaining to the SOA.MNAME, but only if there is a matching NS RR.
* so the second phase (after we find an SOA) is to go looking for the
* NS RRset for that SOA's zone.
*
* no answer section processed by this code is allowed to contain CNAME
* or DNAME RR's. for the SOA query this means we strip a label and
* keep going. for the NS and A queries this means we just give up.
*/
isc_result_t
res_findzonecut(res_state statp, const char *dname, ns_class class, int opts,
char *zname, size_t zsize, struct in_addr *addrs, int naddrs,
int *count, void *zcookie)
{
char mname[NS_MAXDNAME];
u_long save_pfcode;
rrset_ns nsrrs;
int n = 0;
isc_result_t rcode;
DPRINTF(("START dname='%s' class=%s, zsize=%ld, naddrs=%d",
dname, p_class(class), (long)zsize, naddrs));
save_pfcode = statp->pfcode;
statp->pfcode |= RES_PRF_HEAD2 | RES_PRF_HEAD1 | RES_PRF_HEADX |
RES_PRF_QUES | RES_PRF_ANS |
RES_PRF_AUTH | RES_PRF_ADD;
ISC_LIST_INIT(nsrrs);
DPRINTF (("look for a predefined zone statement"));
rcode = find_cached_zone (dname, class, zname, zsize,
addrs, naddrs, &n, zcookie);
if (rcode == ISC_R_SUCCESS)
goto done;
DPRINTF(("get the soa, and see if it has enough glue"));
if ((rcode = get_soa(statp, dname, class, zname, zsize,
mname, sizeof mname, &nsrrs)) != ISC_R_SUCCESS ||
((opts & RES_EXHAUSTIVE) == 0 &&
(n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
goto done;
DPRINTF(("get the ns rrset and see if it has enough glue"));
if ((rcode = get_ns(statp, zname, class, &nsrrs)) != ISC_R_SUCCESS ||
((opts & RES_EXHAUSTIVE) == 0 &&
(n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
goto done;
DPRINTF(("get the missing glue and see if it's finally enough"));
if ((rcode = get_glue(statp, class, &nsrrs)) == ISC_R_SUCCESS)
n = satisfy(statp, mname, &nsrrs, addrs, naddrs);
/* If we found the zone, cache it. */
if (n > 0)
cache_found_zone (class, zname, addrs, n);
done:
DPRINTF(("FINISH n=%d (%s)", n, (n < 0) ? strerror(errno) : "OK"));
free_nsrrset(&nsrrs);
statp->pfcode = save_pfcode;
if (count)
*count = n;
return rcode;
}
/* Private. */
static int
satisfy(res_state statp,
const char *mname, rrset_ns *nsrrsp, struct in_addr *addrs, int naddrs)
{
rr_ns *nsrr;
int n, x;
n = 0;
nsrr = find_ns(nsrrsp, mname);
if (nsrr != NULL) {
x = add_addrs(statp, nsrr, addrs, naddrs);
addrs += x;
naddrs -= x;
n += x;
}
for (nsrr = ISC_LIST_HEAD(*nsrrsp);
nsrr != NULL && naddrs > 0;
nsrr = ISC_LIST_NEXT(nsrr, link))
if (ns_samename(nsrr->name, mname) != 1) {
x = add_addrs(statp, nsrr, addrs, naddrs);
addrs += x;
naddrs -= x;
n += x;
}
DPRINTF(("satisfy(%s): %d", mname, n));
return (n);
}
static int
add_addrs(res_state statp, rr_ns *nsrr, struct in_addr *addrs, int naddrs) {
rr_a *arr;
int n = 0;
for (arr = ISC_LIST_HEAD(nsrr->addrs);
arr != NULL; arr = ISC_LIST_NEXT(arr, link)) {
if (naddrs <= 0)
return (0);
*addrs++ = arr->addr;
naddrs--;
n++;
}
DPRINTF(("add_addrs: %d", n));
return (n);
}
static ns_rcode
get_soa(res_state statp, const char *dname, ns_class class,
char *zname, size_t zsize, char *mname, size_t msize,
rrset_ns *nsrrsp)
{
char tname[NS_MAXDNAME];
double resp[NS_PACKETSZ / sizeof (double)];
int n, i, ancount, nscount;
ns_sect sect;
ns_msg msg;
u_int rcode;
isc_result_t status;
/*
* Find closest enclosing SOA, even if it's for the root zone.
*/
/* First canonicalize dname (exactly one unescaped trailing "."). */
status = ns_makecanon(dname, tname, sizeof tname);
if (status != ISC_R_SUCCESS)
return status;
dname = tname;
/* Now grovel the subdomains, hunting for an SOA answer or auth. */
for (;;) {
/* Leading or inter-label '.' are skipped here. */
while (*dname == '.')
dname++;
/* Is there an SOA? */
rcode = do_query(statp, dname, class, ns_t_soa,
resp, &msg, &n);
if (rcode != ISC_R_SUCCESS) {
DPRINTF(("get_soa: do_query('%s', %s) failed (%d)",
dname, p_class(class), n));
return rcode;
}
if (n > 0) {
DPRINTF(("get_soa: CNAME or DNAME found"));
sect = ns_s_max, n = 0;
} else {
ancount = ns_msg_count(msg, ns_s_an);
nscount = ns_msg_count(msg, ns_s_ns);
if (ancount > 0 && rcode == ISC_R_SUCCESS)
sect = ns_s_an, n = ancount;
else if (nscount > 0)
sect = ns_s_ns, n = nscount;
else
sect = ns_s_max, n = 0;
}
for (i = 0; i < n; i++) {
const char *t;
const u_char *rdata;
int rdlen;
ns_rr rr;
rcode = ns_parserr(&msg, sect, i, &rr);
if (rcode != ISC_R_SUCCESS) {
DPRINTF(("get_soa: ns_parserr(%s, %d) failed",
p_section(sect, ns_o_query), i));
return rcode;
}
if (ns_rr_type(rr) == ns_t_cname ||
ns_rr_type(rr) == ns_t_dname)
break;
if (ns_rr_type(rr) != ns_t_soa ||
ns_rr_class(rr) != class)
continue;
t = ns_rr_name(rr);
switch (sect) {
case ns_s_an:
if (ns_samedomain(dname, t) == 0) {
DPRINTF(("get_soa: %s'%s', '%s') == 0",
"ns_samedomain(", dname, t));
return ISC_R_NOTZONE;
}
break;
case ns_s_ns:
if (ns_samename(dname, t) == 1 ||
ns_samedomain(dname, t) == 0) {
DPRINTF(("get_soa: %smain('%s', '%s')",
"ns_samename() || !ns_samedo",
dname, t));
return ISC_R_NOTZONE;
}
break;
default:
abort();
}
if (strlen(t) + 1 > zsize) {
DPRINTF(("get_soa: zname(%d) too small (%d)",
zsize, strlen(t) + 1));
return ISC_R_NOSPACE;
}
strcpy(zname, t);
rdata = ns_rr_rdata(rr);
rdlen = ns_rr_rdlen(rr);
if (ns_name_uncompress((u_char *)resp,
ns_msg_end(msg), rdata,
mname, msize) < 0) {
DPRINTF(("get_soa: %s failed",
"ns_name_uncompress"));
return ISC_R_NOMEMORY;
}
rcode = save_ns(statp, &msg,
ns_s_ns, zname, class, nsrrsp);
if (rcode != ISC_R_SUCCESS) {
DPRINTF(("get_soa: save_ns failed"));
return rcode;
}
return ISC_R_SUCCESS;
}
/* If we're out of labels, then not even "." has an SOA! */
if (*dname == '\0')
break;
/* Find label-terminating "."; top of loop will skip it. */
while (*dname != '.') {
if (*dname == '\\')
if (*++dname == '\0') {
return ISC_R_NOSPACE;
}
dname++;
}
}
DPRINTF(("get_soa: out of labels"));
return ISC_R_DESTADDRREQ;
}
static isc_result_t
get_ns(res_state statp, const char *zname, ns_class class, rrset_ns *nsrrsp) {
double resp[NS_PACKETSZ / sizeof (double)];
ns_msg msg;
int n;
isc_result_t rcode;
/* Go and get the NS RRs for this zone. */
rcode = do_query(statp, zname, class, ns_t_ns, resp, &msg, &n);
if (rcode != ISC_R_SUCCESS) {
DPRINTF(("get_ns: do_query('zname', %s) failed (%d)",
zname, p_class(class), rcode));
return rcode;
}
/* Remember the NS RRs and associated A RRs that came back. */
rcode = save_ns(statp, &msg, ns_s_an, zname, class, nsrrsp);
if (rcode != ISC_R_SUCCESS) {
DPRINTF(("get_ns save_ns('%s', %s) failed",
zname, p_class(class)));
return rcode;
}
return ISC_R_SUCCESS;
}
static isc_result_t
get_glue(res_state statp, ns_class class, rrset_ns *nsrrsp) {
rr_ns *nsrr, *nsrr_n;
/* Go and get the A RRs for each empty NS RR on our list. */
for (nsrr = ISC_LIST_HEAD(*nsrrsp); nsrr != NULL; nsrr = nsrr_n) {
double resp[NS_PACKETSZ / sizeof (double)];
ns_msg msg;
int n;
isc_result_t rcode;
nsrr_n = ISC_LIST_NEXT(nsrr, link);
if (ISC_LIST_EMPTY(nsrr->addrs)) {
rcode = do_query(statp, nsrr->name, class, ns_t_a,
resp, &msg, &n);
if (rcode != ISC_R_SUCCESS) {
DPRINTF(("get_glue: do_query('%s', %s') failed",
nsrr->name, p_class(class)));
return rcode;
}
if (n > 0) {
DPRINTF((
"get_glue: do_query('%s', %s') CNAME or DNAME found",
nsrr->name, p_class(class)));
}
rcode = save_a(statp, &msg, ns_s_an, nsrr->name, class,
&nsrr->addrs);
if (rcode != ISC_R_SUCCESS) {
DPRINTF(("get_glue: save_r('%s', %s) failed",
nsrr->name, p_class(class)));
return rcode;
}
/* If it's still empty, it's just chaff. */
if (ISC_LIST_EMPTY(nsrr->addrs)) {
DPRINTF(("get_glue: removing empty '%s' NS",
nsrr->name));
free_nsrr(nsrrsp, nsrr);
}
}
}
return ISC_R_SUCCESS;
}
static isc_result_t
save_ns(res_state statp, ns_msg *msg, ns_sect sect,
const char *owner, ns_class class,
rrset_ns *nsrrsp)
{
int i;
isc_result_t rcode;
for (i = 0; i < ns_msg_count(*msg, sect); i++) {
char tname[MAXDNAME];
const u_char *rdata;
rr_ns *nsrr;
ns_rr rr;
int rdlen;
rcode = ns_parserr(msg, sect, i, &rr);
if (rcode != ISC_R_SUCCESS) {
DPRINTF(("save_ns: ns_parserr(%s, %d) failed",
p_section(sect, ns_o_query), i));
return rcode;
}
if (ns_rr_type(rr) != ns_t_ns ||
ns_rr_class(rr) != class ||
ns_samename(ns_rr_name(rr), owner) != 1)
continue;
nsrr = find_ns(nsrrsp, ns_rr_name(rr));
if (nsrr == NULL) {
nsrr = malloc(sizeof *nsrr);
if (nsrr == NULL) {
DPRINTF(("save_ns: malloc failed"));
return ISC_R_NOMEMORY;
}
rdata = ns_rr_rdata(rr);
rdlen = ns_rr_rdlen(rr);
if (ns_name_uncompress(ns_msg_base(*msg),
ns_msg_end(*msg), rdata,
tname, sizeof tname) < 0) {
DPRINTF(("save_ns: ns_name_uncompress failed"));
free(nsrr);
return ISC_R_NOMEMORY;
}
nsrr->name = strdup(tname);
if (nsrr->name == NULL) {
DPRINTF(("save_ns: strdup failed"));
free(nsrr);
return ISC_R_NOMEMORY;
}
ISC_LIST_INIT(nsrr->addrs);
ISC_LIST_APPEND(*nsrrsp, nsrr, link);
}
rcode = save_a(statp, msg, ns_s_ar,
nsrr->name, class, &nsrr->addrs);
if (rcode != ISC_R_SUCCESS) {
DPRINTF(("save_ns: save_r('%s', %s) failed",
nsrr->name, p_class(class)));
return rcode;
}
}
return ISC_R_SUCCESS;
}
static isc_result_t
save_a(res_state statp, ns_msg *msg, ns_sect sect,
const char *owner, ns_class class,
rrset_a *arrsp)
{
int i;
isc_result_t rcode;
for (i = 0; i < ns_msg_count(*msg, sect); i++) {
ns_rr rr;
rr_a *arr;
rcode = ns_parserr(msg, sect, i, &rr);
if (rcode != ISC_R_SUCCESS) {
DPRINTF(("save_a: ns_parserr(%s, %d) failed",
p_section(sect, ns_o_query), i));
return rcode;
}
if (ns_rr_type(rr) != ns_t_a ||
ns_rr_class(rr) != class ||
ns_samename(ns_rr_name(rr), owner) != 1 ||
ns_rr_rdlen(rr) != NS_INADDRSZ)
continue;
arr = malloc(sizeof *arr);
if (arr == NULL) {
DPRINTF(("save_a: malloc failed"));
return ISC_R_NOMEMORY;
}
memcpy(&arr->addr, ns_rr_rdata(rr), NS_INADDRSZ);
ISC_LIST_APPEND(*arrsp, arr, link);
}
return ISC_R_SUCCESS;
}
static void
free_nsrrset(rrset_ns *nsrrsp) {
rr_ns *nsrr;
while ((nsrr = ISC_LIST_HEAD(*nsrrsp)) != NULL)
free_nsrr(nsrrsp, nsrr);
}
static void
free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) {
rr_a *arr;
while ((arr = ISC_LIST_HEAD(nsrr->addrs)) != NULL) {
ISC_LIST_UNLINK(nsrr->addrs, arr, link);
free(arr);
}
free((char *)nsrr->name);
ISC_LIST_UNLINK(*nsrrsp, nsrr, link);
free(nsrr);
}
static rr_ns *
find_ns(rrset_ns *nsrrsp, const char *dname) {
rr_ns *nsrr;
for (nsrr = ISC_LIST_HEAD(*nsrrsp);
nsrr != NULL; nsrr = ISC_LIST_NEXT(nsrr, link))
if (ns_samename(nsrr->name, dname) == 1)
return (nsrr);
return (NULL);
}
static isc_result_t
do_query(res_state statp, const char *dname, ns_class class, ns_type qtype,
double *resp, ns_msg *msg, int *alias_count)
{
double req[NS_PACKETSZ / sizeof (double)];
int i;
unsigned n;
isc_result_t status;
status = res_nmkquery(statp, ns_o_query, dname, class, qtype,
NULL, 0, NULL, req, NS_PACKETSZ, &n);
if (status != ISC_R_SUCCESS) {
DPRINTF(("do_query: res_nmkquery failed"));
return status;
}
status = res_nsend(statp, req, n, resp, NS_PACKETSZ, &n);
if (status != ISC_R_SUCCESS) {
DPRINTF(("do_query: res_nsend failed"));
return status;
}
if (n == 0) {
DPRINTF(("do_query: res_nsend returned 0"));
return ISC_R_NOTFOUND;
}
if (ns_initparse((u_char *)resp, n, msg) != ISC_R_SUCCESS) {
DPRINTF(("do_query: ns_initparse failed"));
return ISC_R_NOSPACE;
}
n = 0;
for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) {
ns_rr rr;
status = ns_parserr(msg, ns_s_an, i, &rr);
if (status != ISC_R_SUCCESS) {
DPRINTF(("do_query: ns_parserr failed"));
return status;
}
n += (ns_rr_class(rr) == class &&
(ns_rr_type(rr) == ns_t_cname ||
ns_rr_type(rr) == ns_t_dname));
}
if (alias_count)
*alias_count = n;
return ISC_R_SUCCESS;
}
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