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NetBSD/lib/libresolv/res_findzonecut.c

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/* $NetBSD: res_findzonecut.c,v 1.1 2012/11/15 18:48:48 christos Exp $ */
/*
* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
* Copyright (c) 1999 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.
*/
#include <sys/cdefs.h>
#if 0
static const char rcsid[] = "Id: res_findzonecut.c,v 1.10 2005/10/11 00:10:16 marka Exp ";
#else
__RCSID("$NetBSD: res_findzonecut.c,v 1.1 2012/11/15 18:48:48 christos Exp $");
#endif
/* Import. */
#include "port_before.h"
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/queue.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <errno.h>
#include <limits.h>
#include <netdb.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "port_after.h"
#include <resolv.h>
/* Data structures. */
typedef struct rr_a {
TAILQ_ENTRY(rr_a) link;
union res_sockaddr_union addr;
} rr_a;
typedef TAILQ_HEAD(rrset_a, rr_a) rrset_a;
typedef struct rr_ns {
TAILQ_ENTRY(rr_ns) link;
const char * name;
unsigned int flags;
rrset_a addrs;
} rr_ns;
typedef TAILQ_HEAD(rrset_ns, rr_ns) rrset_ns;
#define RR_NS_HAVE_V4 0x01
#define RR_NS_HAVE_V6 0x02
/* Forward. */
static int satisfy(res_state, const char *, rrset_ns *,
union res_sockaddr_union *, int);
static int add_addrs(res_state, rr_ns *,
union res_sockaddr_union *, int);
static int get_soa(res_state, const char *, ns_class, int,
char *, size_t, char *, size_t,
rrset_ns *);
static int get_ns(res_state, const char *, ns_class, int, rrset_ns *);
static int get_glue(res_state, ns_class, int, rrset_ns *);
static int save_ns(res_state, ns_msg *, ns_sect,
const char *, ns_class, int, rrset_ns *);
static int save_a(res_state, ns_msg *, ns_sect,
const char *, ns_class, int, rr_ns *);
static void free_nsrrset(rrset_ns *);
static void free_nsrr(rrset_ns *, rr_ns *);
static rr_ns * find_ns(rrset_ns *, const char *);
static int do_query(res_state, const char *, ns_class, ns_type,
u_char *, ns_msg *);
static void res_dprintf(const char *, ...) ISC_FORMAT_PRINTF(1, 2);
/* Macros. */
#define DPRINTF(x) do {\
int save_errno = errno; \
if ((statp->options & RES_DEBUG) != 0U) res_dprintf x; \
errno = save_errno; \
} while (/*CONSTCOND*/0)
/* Public. */
/*%
* find enclosing zone for a <dname,class>, and some server addresses
*
* parameters:
*\li res - resolver context to work within (is modified)
*\li dname - domain name whose enclosing zone is desired
*\li class - class of dname (and its enclosing zone)
*\li zname - found zone name
*\li zsize - allocated size of zname
*\li addrs - found server addresses
*\li naddrs - max number of addrs
*
* return values:
*\li < 0 - an error occurred (check errno)
*\li = 0 - zname is now valid, but addrs[] wasn't changed
*\li > 0 - zname is now valid, and return value is number of addrs[] found
*
* notes:
*\li this function calls res_nsend() which means it depends on correctly
* functioning recursive nameservers (usually defined in /etc/resolv.conf
* or its local equivilent).
*
*\li 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.
*
*\li 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.
*
*\li 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.
*
*\li 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."
*
*\li 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.
*
*\li 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.
*/
int
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 result, i;
union res_sockaddr_union *u;
opts |= RES_IPV4ONLY;
opts &= ~RES_IPV6ONLY;
u = calloc(naddrs, sizeof(*u));
if (u == NULL)
return(-1);
result = res_findzonecut2(statp, dname, class, opts, zname, zsize,
u, naddrs);
for (i = 0; i < result; i++) {
addrs[i] = u[i].sin.sin_addr;
}
free(u);
return (result);
}
int
res_findzonecut2(res_state statp, const char *dname, ns_class class, int opts,
char *zname, size_t zsize, union res_sockaddr_union *addrs,
int naddrs)
{
char mname[NS_MAXDNAME];
u_long save_pfcode;
rrset_ns nsrrs;
int n;
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;
TAILQ_INIT(&nsrrs);
DPRINTF(("get the soa, and see if it has enough glue"));
if ((n = get_soa(statp, dname, class, opts, zname, zsize,
mname, sizeof mname, &nsrrs)) < 0 ||
((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 ((n = get_ns(statp, zname, class, opts, &nsrrs)) < 0 ||
((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 ((n = get_glue(statp, class, opts, &nsrrs)) >= 0)
n = satisfy(statp, mname, &nsrrs, addrs, naddrs);
done:
DPRINTF(("FINISH n=%d (%s)", n, (n < 0) ? strerror(errno) : "OK"));
free_nsrrset(&nsrrs);
statp->pfcode = save_pfcode;
return (n);
}
/* Private. */
static int
satisfy(res_state statp, const char *mname, rrset_ns *nsrrsp,
union res_sockaddr_union *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;
}
TAILQ_FOREACH(nsrr, nsrrsp, link) {
if (naddrs <= 0)
break;
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,
union res_sockaddr_union *addrs, int naddrs)
{
rr_a *arr;
int n = 0;
TAILQ_FOREACH(arr, &nsrr->addrs, link) {
if (naddrs <= 0)
return (0);
*addrs++ = arr->addr;
naddrs--;
n++;
}
DPRINTF(("add_addrs: %d", n));
return (n);
}
static int
get_soa(res_state statp, const char *dname, ns_class class, int opts,
char *zname, size_t zsize, char *mname, size_t msize,
rrset_ns *nsrrsp)
{
char tname[NS_MAXDNAME];
u_char *resp = NULL;
int n, i, ancount, nscount;
ns_sect sect;
ns_msg msg;
u_int rcode;
/*
* Find closest enclosing SOA, even if it's for the root zone.
*/
/* First canonicalize dname (exactly one unescaped trailing "."). */
if (ns_makecanon(dname, tname, sizeof tname) < 0)
goto cleanup;
dname = tname;
resp = malloc(NS_MAXMSG);
if (resp == NULL)
goto cleanup;
/* 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? */
n = do_query(statp, dname, class, ns_t_soa, resp, &msg);
if (n < 0) {
DPRINTF(("get_soa: do_query('%s', %s) failed (%d)",
dname, p_class(class), n));
goto cleanup;
}
if (n > 0) {
DPRINTF(("get_soa: CNAME or DNAME found"));
sect = ns_s_max, n = 0;
} else {
rcode = ns_msg_getflag(msg, ns_f_rcode);
ancount = ns_msg_count(msg, ns_s_an);
nscount = ns_msg_count(msg, ns_s_ns);
if (ancount > 0 && rcode == ns_r_noerror)
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;
ns_rr rr;
if (ns_parserr(&msg, sect, i, &rr) < 0) {
DPRINTF(("get_soa: ns_parserr(%s, %d) failed",
p_section(sect, ns_o_query), i));
goto cleanup;
}
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: ns_samedomain('%s', '%s') == 0",
dname, t)
);
errno = EPROTOTYPE;
goto cleanup;
}
break;
case ns_s_ns:
if (ns_samename(dname, t) == 1 ||
ns_samedomain(dname, t) == 0) {
DPRINTF(
("get_soa: ns_samename() || !ns_samedomain('%s', '%s')",
dname, t)
);
errno = EPROTOTYPE;
goto cleanup;
}
break;
default:
abort();
}
if (strlen(t) + 1 > zsize) {
DPRINTF(("get_soa: zname(%lu) too small (%lu)",
(unsigned long)zsize,
(unsigned long)strlen(t) + 1));
errno = EMSGSIZE;
goto cleanup;
}
strcpy(zname, t);
rdata = ns_rr_rdata(rr);
if (ns_name_uncompress(resp, ns_msg_end(msg), rdata,
mname, msize) < 0) {
DPRINTF(("get_soa: ns_name_uncompress failed")
);
goto cleanup;
}
if (save_ns(statp, &msg, ns_s_ns,
zname, class, opts, nsrrsp) < 0) {
DPRINTF(("get_soa: save_ns failed"));
goto cleanup;
}
free(resp);
return (0);
}
/* 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') {
errno = EMSGSIZE;
goto cleanup;
}
dname++;
}
}
DPRINTF(("get_soa: out of labels"));
errno = EDESTADDRREQ;
cleanup:
if (resp != NULL)
free(resp);
return (-1);
}
static int
get_ns(res_state statp, const char *zname, ns_class class, int opts,
rrset_ns *nsrrsp)
{
u_char *resp;
ns_msg msg;
int n;
resp = malloc(NS_MAXMSG);
if (resp == NULL)
return (-1);
/* Go and get the NS RRs for this zone. */
n = do_query(statp, zname, class, ns_t_ns, resp, &msg);
if (n != 0) {
DPRINTF(("get_ns: do_query('%s', %s) failed (%d)",
zname, p_class(class), n));
free(resp);
return (-1);
}
/* Remember the NS RRs and associated A RRs that came back. */
if (save_ns(statp, &msg, ns_s_an, zname, class, opts, nsrrsp) < 0) {
DPRINTF(("get_ns save_ns('%s', %s) failed",
zname, p_class(class)));
free(resp);
return (-1);
}
free(resp);
return (0);
}
static int
get_glue(res_state statp, ns_class class, int opts, rrset_ns *nsrrsp) {
rr_ns *nsrr, *nsrr_n;
u_char *resp;
resp = malloc(NS_MAXMSG);
if (resp == NULL)
return(-1);
/* Go and get the A RRs for each empty NS RR on our list. */
TAILQ_FOREACH_SAFE(nsrr, nsrrsp, link, nsrr_n) {
ns_msg msg;
int n;
if ((nsrr->flags & RR_NS_HAVE_V4) == 0) {
n = do_query(statp, nsrr->name, class, ns_t_a,
resp, &msg);
if (n < 0) {
DPRINTF(
("get_glue: do_query('%s', %s') failed",
nsrr->name, p_class(class)));
goto cleanup;
}
if (n > 0) {
DPRINTF((
"get_glue: do_query('%s', %s') CNAME or DNAME found",
nsrr->name, p_class(class)));
}
if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
opts, nsrr) < 0) {
DPRINTF(("get_glue: save_r('%s', %s) failed",
nsrr->name, p_class(class)));
goto cleanup;
}
}
if ((nsrr->flags & RR_NS_HAVE_V6) == 0) {
n = do_query(statp, nsrr->name, class, ns_t_aaaa,
resp, &msg);
if (n < 0) {
DPRINTF(
("get_glue: do_query('%s', %s') failed",
nsrr->name, p_class(class)));
goto cleanup;
}
if (n > 0) {
DPRINTF((
"get_glue: do_query('%s', %s') CNAME or DNAME found",
nsrr->name, p_class(class)));
}
if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
opts, nsrr) < 0) {
DPRINTF(("get_glue: save_r('%s', %s) failed",
nsrr->name, p_class(class)));
goto cleanup;
}
}
/* If it's still empty, it's just chaff. */
if (TAILQ_EMPTY(&nsrr->addrs)) {
DPRINTF(("get_glue: removing empty '%s' NS",
nsrr->name));
free_nsrr(nsrrsp, nsrr);
}
}
free(resp);
return (0);
cleanup:
free(resp);
return (-1);
}
static int
save_ns(res_state statp, ns_msg *msg, ns_sect sect,
const char *owner, ns_class class, int opts,
rrset_ns *nsrrsp)
{
int i;
for (i = 0; i < ns_msg_count(*msg, sect); i++) {
char tname[MAXDNAME];
const u_char *rdata;
rr_ns *nsrr;
ns_rr rr;
if (ns_parserr(msg, sect, i, &rr) < 0) {
DPRINTF(("save_ns: ns_parserr(%s, %d) failed",
p_section(sect, ns_o_query), i));
return (-1);
}
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 (-1);
}
rdata = ns_rr_rdata(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 (-1);
}
nsrr->name = strdup(tname);
if (nsrr->name == NULL) {
DPRINTF(("save_ns: strdup failed"));
free(nsrr);
return (-1);
}
TAILQ_INIT(&nsrr->addrs);
nsrr->flags = 0;
TAILQ_INSERT_TAIL(nsrrsp, nsrr, link);
}
if (save_a(statp, msg, ns_s_ar,
nsrr->name, class, opts, nsrr) < 0) {
DPRINTF(("save_ns: save_r('%s', %s) failed",
nsrr->name, p_class(class)));
return (-1);
}
}
return (0);
}
static int
save_a(res_state statp, ns_msg *msg, ns_sect sect,
const char *owner, ns_class class, int opts,
rr_ns *nsrr)
{
int i;
for (i = 0; i < ns_msg_count(*msg, sect); i++) {
ns_rr rr;
rr_a *arr;
if (ns_parserr(msg, sect, i, &rr) < 0) {
DPRINTF(("save_a: ns_parserr(%s, %d) failed",
p_section(sect, ns_o_query), i));
return (-1);
}
if ((ns_rr_type(rr) != ns_t_a &&
ns_rr_type(rr) != ns_t_aaaa) ||
ns_rr_class(rr) != class ||
ns_samename(ns_rr_name(rr), owner) != 1 ||
ns_rr_rdlen(rr) != NS_INADDRSZ)
continue;
if ((opts & RES_IPV6ONLY) != 0 && ns_rr_type(rr) != ns_t_aaaa)
continue;
if ((opts & RES_IPV4ONLY) != 0 && ns_rr_type(rr) != ns_t_a)
continue;
arr = malloc(sizeof *arr);
if (arr == NULL) {
DPRINTF(("save_a: malloc failed"));
return (-1);
}
memset(&arr->addr, 0, sizeof(arr->addr));
switch (ns_rr_type(rr)) {
case ns_t_a:
arr->addr.sin.sin_family = AF_INET;
#ifdef HAVE_SA_LEN
arr->addr.sin.sin_len = sizeof(arr->addr.sin);
#endif
memcpy(&arr->addr.sin.sin_addr, ns_rr_rdata(rr),
NS_INADDRSZ);
arr->addr.sin.sin_port = htons(NAMESERVER_PORT);
nsrr->flags |= RR_NS_HAVE_V4;
break;
case ns_t_aaaa:
arr->addr.sin6.sin6_family = AF_INET6;
#ifdef HAVE_SA_LEN
arr->addr.sin6.sin6_len = sizeof(arr->addr.sin6);
#endif
memcpy(&arr->addr.sin6.sin6_addr, ns_rr_rdata(rr), 16);
arr->addr.sin.sin_port = htons(NAMESERVER_PORT);
nsrr->flags |= RR_NS_HAVE_V6;
break;
default:
abort();
}
TAILQ_INSERT_TAIL(&nsrr->addrs, arr, link);
}
return (0);
}
static void
free_nsrrset(rrset_ns *nsrrsp) {
rr_ns *nsrr, *tmp;
TAILQ_FOREACH_SAFE(nsrr, nsrrsp, link, tmp)
free_nsrr(nsrrsp, nsrr);
}
static void
free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) {
rr_a *arr, *n_arr;
char *tmp;
TAILQ_FOREACH_SAFE(arr, &nsrr->addrs, link, n_arr) {
TAILQ_REMOVE(&nsrr->addrs, arr, link);
free(arr);
}
DE_CONST(nsrr->name, tmp);
free(tmp);
TAILQ_REMOVE(nsrrsp, nsrr, link);
free(nsrr);
}
static rr_ns *
find_ns(rrset_ns *nsrrsp, const char *dname) {
rr_ns *nsrr;
TAILQ_FOREACH(nsrr, nsrrsp, link)
if (ns_samename(nsrr->name, dname) == 1)
return (nsrr);
return (NULL);
}
static int
do_query(res_state statp, const char *dname, ns_class class, ns_type qtype,
u_char *resp, ns_msg *msg)
{
u_char req[NS_PACKETSZ];
int i, n;
n = res_nmkquery(statp, ns_o_query, dname, class, qtype,
NULL, 0, NULL, req, NS_PACKETSZ);
if (n < 0) {
DPRINTF(("do_query: res_nmkquery failed"));
return (-1);
}
n = res_nsend(statp, req, n, resp, NS_MAXMSG);
if (n < 0) {
DPRINTF(("do_query: res_nsend failed"));
return (-1);
}
if (n == 0) {
DPRINTF(("do_query: res_nsend returned 0"));
errno = EMSGSIZE;
return (-1);
}
if (ns_initparse(resp, n, msg) < 0) {
DPRINTF(("do_query: ns_initparse failed"));
return (-1);
}
n = 0;
for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) {
ns_rr rr;
if (ns_parserr(msg, ns_s_an, i, &rr) < 0) {
DPRINTF(("do_query: ns_parserr failed"));
return (-1);
}
n += (ns_rr_class(rr) == class &&
(ns_rr_type(rr) == ns_t_cname ||
ns_rr_type(rr) == ns_t_dname));
}
return (n);
}
static void
res_dprintf(const char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
fputs(";; res_findzonecut: ", stderr);
vfprintf(stderr, fmt, ap);
fputc('\n', stderr);
va_end(ap);
}
/*! \file */
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