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48c41d04ee
glibc/resolv/nss_dns/dns-host.c
Siddhesh Poyarekar 48c41d04ee Consider TTL of CNAME record and return minimum TTL in the chain 
[BZ #13928] A DNS request consists of multiple resources combined into
a single hostent, including multiple CNAME records that may have been
assigned different TTL values. In such a case, nscd should take the
least TTL among all of the resources as the timeout for the hostent
before it is reloaded in its cache so that the hostent remains stale
in the database for the least amount of time.
2012-03-30 21:30:01 +05:30

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/* Copyright (C) 1996-2004, 2007-2010, 2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Extended from original form by Ulrich Drepper <drepper@cygnus.com>, 1996.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
/* Parts of this file are plain copies of the file `gethtnamadr.c' from
the bind package and it has the following copyright. */
/*
* ++Copyright++ 1985, 1988, 1993
* -
* Copyright (c) 1985, 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* -
* Portions Copyright (c) 1993 by Digital Equipment Corporation.
*
* 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, and that
* the name of Digital Equipment Corporation not be used in advertising or
* publicity pertaining to distribution of the document or software without
* specific, written prior permission.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
* WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
* CORPORATION 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.
* -
* --Copyright--
*/
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <sys/syslog.h>
#include "nsswitch.h"
/* Get implementation for some internal functions. */
#include <resolv/mapv4v6addr.h>
#include <resolv/mapv4v6hostent.h>
#define RESOLVSORT
/* Maximum number of aliases we allow. */
#define MAX_NR_ALIASES 48
#define MAX_NR_ADDRS 48
#if PACKETSZ > 65536
# define MAXPACKET PACKETSZ
#else
# define MAXPACKET 65536
#endif
/* As per RFC 1034 and 1035 a host name cannot exceed 255 octets in length. */
#ifdef MAXHOSTNAMELEN
# undef MAXHOSTNAMELEN
#endif
#define MAXHOSTNAMELEN 256
static const char AskedForGot[] = "\
gethostby*.getanswer: asked for \"%s\", got \"%s\"";
/* We need this time later. */
typedef union querybuf
{
HEADER hdr;
u_char buf[MAXPACKET];
} querybuf;
/* These functions are defined in res_comp.c. */
#define NS_MAXCDNAME 255 /* maximum compressed domain name */
extern int __ns_name_ntop (const u_char *, char *, size_t);
extern int __ns_name_unpack (const u_char *, const u_char *,
const u_char *, u_char *, size_t);
static enum nss_status getanswer_r (const querybuf *answer, int anslen,
const char *qname, int qtype,
struct hostent *result, char *buffer,
size_t buflen, int *errnop, int *h_errnop,
int map, int32_t *ttlp, char **canonp);
static enum nss_status gaih_getanswer (const querybuf *answer1, int anslen1,
const querybuf *answer2, int anslen2,
const char *qname,
struct gaih_addrtuple **pat,
char *buffer, size_t buflen,
int *errnop, int *h_errnop,
int32_t *ttlp);
extern enum nss_status _nss_dns_gethostbyname3_r (const char *name, int af,
struct hostent *result,
char *buffer, size_t buflen,
int *errnop, int *h_errnop,
int32_t *ttlp,
char **canonp);
hidden_proto (_nss_dns_gethostbyname3_r)
enum nss_status
_nss_dns_gethostbyname3_r (const char *name, int af, struct hostent *result,
char *buffer, size_t buflen, int *errnop,
int *h_errnop, int32_t *ttlp, char **canonp)
{
union
{
querybuf *buf;
u_char *ptr;
} host_buffer;
querybuf *orig_host_buffer;
char tmp[NS_MAXDNAME];
int size, type, n;
const char *cp;
int map = 0;
int olderr = errno;
enum nss_status status;
if (__res_maybe_init (&_res, 0) == -1)
return NSS_STATUS_UNAVAIL;
switch (af) {
case AF_INET:
size = INADDRSZ;
type = T_A;
break;
case AF_INET6:
size = IN6ADDRSZ;
type = T_AAAA;
break;
default:
*h_errnop = NO_DATA;
*errnop = EAFNOSUPPORT;
return NSS_STATUS_UNAVAIL;
}
result->h_addrtype = af;
result->h_length = size;
/*
* if there aren't any dots, it could be a user-level alias.
* this is also done in res_query() since we are not the only
* function that looks up host names.
*/
if (strchr (name, '.') == NULL
&& (cp = res_hostalias (&_res, name, tmp, sizeof (tmp))) != NULL)
name = cp;
host_buffer.buf = orig_host_buffer = (querybuf *) alloca (1024);
n = __libc_res_nsearch (&_res, name, C_IN, type, host_buffer.buf->buf,
1024, &host_buffer.ptr, NULL, NULL, NULL);
if (n < 0)
{
switch (errno)
{
case ESRCH:
status = NSS_STATUS_TRYAGAIN;
h_errno = TRY_AGAIN;
break;
case ECONNREFUSED:
case ETIMEDOUT:
status = NSS_STATUS_UNAVAIL;
break;
default:
status = NSS_STATUS_NOTFOUND;
break;
}
*h_errnop = h_errno;
if (h_errno == TRY_AGAIN)
*errnop = EAGAIN;
else
__set_errno (olderr);
/* If we are looking for an IPv6 address and mapping is enabled
by having the RES_USE_INET6 bit in _res.options set, we try
another lookup. */
if (af == AF_INET6 && (_res.options & RES_USE_INET6))
n = __libc_res_nsearch (&_res, name, C_IN, T_A, host_buffer.buf->buf,
host_buffer.buf != orig_host_buffer
? MAXPACKET : 1024, &host_buffer.ptr,
NULL, NULL, NULL);
if (n < 0)
{
if (host_buffer.buf != orig_host_buffer)
free (host_buffer.buf);
return status;
}
map = 1;
result->h_addrtype = AF_INET;
result->h_length = INADDRSZ;
}
status = getanswer_r (host_buffer.buf, n, name, type, result, buffer, buflen,
errnop, h_errnop, map, ttlp, canonp);
if (host_buffer.buf != orig_host_buffer)
free (host_buffer.buf);
return status;
}
hidden_def (_nss_dns_gethostbyname3_r)
enum nss_status
_nss_dns_gethostbyname2_r (const char *name, int af, struct hostent *result,
char *buffer, size_t buflen, int *errnop,
int *h_errnop)
{
return _nss_dns_gethostbyname3_r (name, af, result, buffer, buflen, errnop,
h_errnop, NULL, NULL);
}
enum nss_status
_nss_dns_gethostbyname_r (const char *name, struct hostent *result,
char *buffer, size_t buflen, int *errnop,
int *h_errnop)
{
enum nss_status status = NSS_STATUS_NOTFOUND;
if (_res.options & RES_USE_INET6)
status = _nss_dns_gethostbyname3_r (name, AF_INET6, result, buffer,
buflen, errnop, h_errnop, NULL, NULL);
if (status == NSS_STATUS_NOTFOUND)
status = _nss_dns_gethostbyname3_r (name, AF_INET, result, buffer,
buflen, errnop, h_errnop, NULL, NULL);
return status;
}
enum nss_status
_nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
char *buffer, size_t buflen, int *errnop,
int *herrnop, int32_t *ttlp)
{
if (__res_maybe_init (&_res, 0) == -1)
return NSS_STATUS_UNAVAIL;
/*
* if there aren't any dots, it could be a user-level alias.
* this is also done in res_query() since we are not the only
* function that looks up host names.
*/
if (strchr (name, '.') == NULL)
{
char *tmp = alloca (NS_MAXDNAME);
const char *cp = res_hostalias (&_res, name, tmp, NS_MAXDNAME);
if (cp != NULL)
name = cp;
}
union
{
querybuf *buf;
u_char *ptr;
} host_buffer;
querybuf *orig_host_buffer;
host_buffer.buf = orig_host_buffer = (querybuf *) alloca (2048);
u_char *ans2p = NULL;
int nans2p = 0;
int resplen2 = 0;
int olderr = errno;
enum nss_status status;
int n = __libc_res_nsearch (&_res, name, C_IN, T_UNSPEC,
host_buffer.buf->buf, 2048, &host_buffer.ptr,
&ans2p, &nans2p, &resplen2);
if (n < 0)
{
if (errno == ESRCH)
{
status = NSS_STATUS_TRYAGAIN;
h_errno = TRY_AGAIN;
}
else
status = (errno == ECONNREFUSED
? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND);
*herrnop = h_errno;
if (h_errno == TRY_AGAIN)
*errnop = EAGAIN;
else
__set_errno (olderr);
if (host_buffer.buf != orig_host_buffer)
free (host_buffer.buf);
return status;
}
status = gaih_getanswer(host_buffer.buf, n, (const querybuf *) ans2p,
resplen2, name, pat, buffer, buflen,
errnop, herrnop, ttlp);
if (host_buffer.buf != orig_host_buffer)
free (host_buffer.buf);
return status;
}
extern enum nss_status _nss_dns_gethostbyaddr2_r (const void *addr,
socklen_t len, int af,
struct hostent *result,
char *buffer, size_t buflen,
int *errnop, int *h_errnop,
int32_t *ttlp);
hidden_proto (_nss_dns_gethostbyaddr2_r)
enum nss_status
_nss_dns_gethostbyaddr2_r (const void *addr, socklen_t len, int af,
struct hostent *result, char *buffer, size_t buflen,
int *errnop, int *h_errnop, int32_t *ttlp)
{
static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
static const u_char v6local[] = { 0,0, 0,1 };
const u_char *uaddr = (const u_char *)addr;
struct host_data
{
char *aliases[MAX_NR_ALIASES];
unsigned char host_addr[16]; /* IPv4 or IPv6 */
char *h_addr_ptrs[MAX_NR_ADDRS + 1];
char linebuffer[0];
} *host_data = (struct host_data *) buffer;
union
{
querybuf *buf;
u_char *ptr;
} host_buffer;
querybuf *orig_host_buffer;
char qbuf[MAXDNAME+1], *qp = NULL;
size_t size;
int n, status;
int olderr = errno;
uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct host_data);
buffer += pad;
buflen = buflen > pad ? buflen - pad : 0;
if (__builtin_expect (buflen < sizeof (struct host_data), 0))
{
*errnop = ERANGE;
*h_errnop = NETDB_INTERNAL;
return NSS_STATUS_TRYAGAIN;
}
host_data = (struct host_data *) buffer;
if (__res_maybe_init (&_res, 0) == -1)
return NSS_STATUS_UNAVAIL;
if (af == AF_INET6 && len == IN6ADDRSZ
&& (memcmp (uaddr, mapped, sizeof mapped) == 0
|| (memcmp (uaddr, tunnelled, sizeof tunnelled) == 0
&& memcmp (&uaddr[sizeof tunnelled], v6local, sizeof v6local))))
{
/* Unmap. */
addr += sizeof mapped;
uaddr += sizeof mapped;
af = AF_INET;
len = INADDRSZ;
}
switch (af)
{
case AF_INET:
size = INADDRSZ;
break;
case AF_INET6:
size = IN6ADDRSZ;
break;
default:
*errnop = EAFNOSUPPORT;
*h_errnop = NETDB_INTERNAL;
return NSS_STATUS_UNAVAIL;
}
if (size > len)
{
*errnop = EAFNOSUPPORT;
*h_errnop = NETDB_INTERNAL;
return NSS_STATUS_UNAVAIL;
}
host_buffer.buf = orig_host_buffer = (querybuf *) alloca (1024);
switch (af)
{
case AF_INET:
sprintf (qbuf, "%u.%u.%u.%u.in-addr.arpa", (uaddr[3] & 0xff),
(uaddr[2] & 0xff), (uaddr[1] & 0xff), (uaddr[0] & 0xff));
break;
case AF_INET6:
/* Only lookup with the byte string format if the user wants it. */
if (__builtin_expect (_res.options & RES_USEBSTRING, 0))
{
qp = stpcpy (qbuf, "\\[x");
for (n = 0; n < IN6ADDRSZ; ++n)
qp += sprintf (qp, "%02hhx", uaddr[n]);
strcpy (qp, "].ip6.arpa");
n = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR,
host_buffer.buf->buf, 1024, &host_buffer.ptr,
NULL, NULL, NULL);
if (n >= 0)
goto got_it_already;
}
qp = qbuf;
for (n = IN6ADDRSZ - 1; n >= 0; n--)
{
static const char nibblechar[16] = "0123456789abcdef";
*qp++ = nibblechar[uaddr[n] & 0xf];
*qp++ = '.';
*qp++ = nibblechar[(uaddr[n] >> 4) & 0xf];
*qp++ = '.';
}
strcpy(qp, "ip6.arpa");
break;
default:
/* Cannot happen. */
break;
}
n = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, host_buffer.buf->buf,
1024, &host_buffer.ptr, NULL, NULL, NULL);
if (n < 0 && af == AF_INET6 && (_res.options & RES_NOIP6DOTINT) == 0)
{
strcpy (qp, "ip6.int");
n = __libc_res_nquery (&_res, qbuf, C_IN, T_PTR, host_buffer.buf->buf,
host_buffer.buf != orig_host_buffer
? MAXPACKET : 1024, &host_buffer.ptr,
NULL, NULL, NULL);
}
if (n < 0)
{
*h_errnop = h_errno;
__set_errno (olderr);
if (host_buffer.buf != orig_host_buffer)
free (host_buffer.buf);
return errno == ECONNREFUSED ? NSS_STATUS_UNAVAIL : NSS_STATUS_NOTFOUND;
}
got_it_already:
status = getanswer_r (host_buffer.buf, n, qbuf, T_PTR, result, buffer, buflen,
errnop, h_errnop, 0 /* XXX */, ttlp, NULL);
if (host_buffer.buf != orig_host_buffer)
free (host_buffer.buf);
if (status != NSS_STATUS_SUCCESS)
return status;
#ifdef SUNSECURITY
This is not implemented because it is not possible to use the current
source from bind in a multi-threaded program.
#endif
result->h_addrtype = af;
result->h_length = len;
memcpy (host_data->host_addr, addr, len);
host_data->h_addr_ptrs[0] = (char *) host_data->host_addr;
host_data->h_addr_ptrs[1] = NULL;
#if 0
/* XXX I think this is wrong. Why should an IPv4 address be
converted to IPv6 if the user explicitly asked for IPv4? */
if (af == AF_INET && (_res.options & RES_USE_INET6))
{
map_v4v6_address ((char *) host_data->host_addr,
(char *) host_data->host_addr);
result->h_addrtype = AF_INET6;
result->h_length = IN6ADDRSZ;
}
#endif
*h_errnop = NETDB_SUCCESS;
return NSS_STATUS_SUCCESS;
}
hidden_def (_nss_dns_gethostbyaddr2_r)
enum nss_status
_nss_dns_gethostbyaddr_r (const void *addr, socklen_t len, int af,
struct hostent *result, char *buffer, size_t buflen,
int *errnop, int *h_errnop)
{
return _nss_dns_gethostbyaddr2_r (addr, len, af, result, buffer, buflen,
errnop, h_errnop, NULL);
}
#ifdef RESOLVSORT
static void addrsort (char **ap, int num);
static void
addrsort (char **ap, int num)
{
int i, j;
char **p;
short aval[MAX_NR_ADDRS];
int needsort = 0;
p = ap;
if (num > MAX_NR_ADDRS)
num = MAX_NR_ADDRS;
for (i = 0; i < num; i++, p++)
{
for (j = 0 ; (unsigned)j < _res.nsort; j++)
if (_res.sort_list[j].addr.s_addr ==
(((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
break;
aval[i] = j;
if (needsort == 0 && i > 0 && j < aval[i-1])
needsort = i;
}
if (!needsort)
return;
while (needsort++ < num)
for (j = needsort - 2; j >= 0; j--)
if (aval[j] > aval[j+1])
{
char *hp;
i = aval[j];
aval[j] = aval[j+1];
aval[j+1] = i;
hp = ap[j];
ap[j] = ap[j+1];
ap[j+1] = hp;
}
else
break;
}
#endif
static enum nss_status
getanswer_r (const querybuf *answer, int anslen, const char *qname, int qtype,
struct hostent *result, char *buffer, size_t buflen,
int *errnop, int *h_errnop, int map, int32_t *ttlp, char **canonp)
{
struct host_data
{
char *aliases[MAX_NR_ALIASES];
unsigned char host_addr[16]; /* IPv4 or IPv6 */
char *h_addr_ptrs[0];
} *host_data;
int linebuflen;
register const HEADER *hp;
const u_char *end_of_message, *cp;
int n, ancount, qdcount;
int haveanswer, had_error;
char *bp, **ap, **hap;
char tbuf[MAXDNAME];
const char *tname;
int (*name_ok) (const char *);
u_char packtmp[NS_MAXCDNAME];
int have_to_map = 0;
uintptr_t pad = -(uintptr_t) buffer % __alignof__ (struct host_data);
buffer += pad;
if (__builtin_expect (buflen < sizeof (struct host_data) + pad, 0))
{
/* The buffer is too small. */
too_small:
*errnop = ERANGE;
*h_errnop = NETDB_INTERNAL;
return NSS_STATUS_TRYAGAIN;
}
host_data = (struct host_data *) buffer;
linebuflen = buflen - sizeof (struct host_data);
if (buflen - sizeof (struct host_data) != linebuflen)
linebuflen = INT_MAX;
tname = qname;
result->h_name = NULL;
end_of_message = answer->buf + anslen;
switch (qtype)
{
case T_A:
case T_AAAA:
name_ok = res_hnok;
break;
case T_PTR:
name_ok = res_dnok;
break;
default:
*errnop = ENOENT;
return NSS_STATUS_UNAVAIL; /* XXX should be abort(); */
}
/*
* find first satisfactory answer
*/
hp = &answer->hdr;
ancount = ntohs (hp->ancount);
qdcount = ntohs (hp->qdcount);
cp = answer->buf + HFIXEDSZ;
if (__builtin_expect (qdcount, 1) != 1)
{
*h_errnop = NO_RECOVERY;
return NSS_STATUS_UNAVAIL;
}
if (sizeof (struct host_data) + (ancount + 1) * sizeof (char *) >= buflen)
goto too_small;
bp = (char *) &host_data->h_addr_ptrs[ancount + 1];
linebuflen -= (ancount + 1) * sizeof (char *);
n = __ns_name_unpack (answer->buf, end_of_message, cp,
packtmp, sizeof packtmp);
if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
{
if (__builtin_expect (errno, 0) == EMSGSIZE)
goto too_small;
n = -1;
}
if (n > 0 && bp[0] == '.')
bp[0] = '\0';
if (__builtin_expect (n < 0 || ((*name_ok) (bp) == 0 && (errno = EBADMSG)),
0))
{
*errnop = errno;
*h_errnop = NO_RECOVERY;
return NSS_STATUS_UNAVAIL;
}
cp += n + QFIXEDSZ;
if (qtype == T_A || qtype == T_AAAA)
{
/* res_send() has already verified that the query name is the
* same as the one we sent; this just gets the expanded name
* (i.e., with the succeeding search-domain tacked on).
*/
n = strlen (bp) + 1; /* for the \0 */
if (n >= MAXHOSTNAMELEN)
{
*h_errnop = NO_RECOVERY;
*errnop = ENOENT;
return NSS_STATUS_TRYAGAIN;
}
result->h_name = bp;
bp += n;
linebuflen -= n;
if (linebuflen < 0)
goto too_small;
/* The qname can be abbreviated, but h_name is now absolute. */
qname = result->h_name;
}
ap = host_data->aliases;
*ap = NULL;
result->h_aliases = host_data->aliases;
hap = host_data->h_addr_ptrs;
*hap = NULL;
result->h_addr_list = host_data->h_addr_ptrs;
haveanswer = 0;
had_error = 0;
while (ancount-- > 0 && cp < end_of_message && had_error == 0)
{
int type, class;
n = __ns_name_unpack (answer->buf, end_of_message, cp,
packtmp, sizeof packtmp);
if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
{
if (__builtin_expect (errno, 0) == EMSGSIZE)
goto too_small;
n = -1;
}
if (__builtin_expect (n < 0 || (*name_ok) (bp) == 0, 0))
{
++had_error;
continue;
}
cp += n; /* name */
if (__builtin_expect (cp + 10 > end_of_message, 0))
{
++had_error;
continue;
}
type = __ns_get16 (cp);
cp += INT16SZ; /* type */
class = __ns_get16 (cp);
cp += INT16SZ; /* class */
int32_t ttl = __ns_get32 (cp);
cp += INT32SZ; /* TTL */
n = __ns_get16 (cp);
cp += INT16SZ; /* len */
if (__builtin_expect (class != C_IN, 0))
{
/* XXX - debug? syslog? */
cp += n;
continue; /* XXX - had_error++ ? */
}
if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME)
{
/* A CNAME could also have a TTL entry. */
if (ttlp != NULL && ttl < *ttlp)
*ttlp = ttl;
if (ap >= &host_data->aliases[MAX_NR_ALIASES - 1])
continue;
n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf);
if (__builtin_expect (n < 0 || (*name_ok) (tbuf) == 0, 0))
{
++had_error;
continue;
}
cp += n;
/* Store alias. */
*ap++ = bp;
n = strlen (bp) + 1; /* For the \0. */
if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN)
{
++had_error;
continue;
}
bp += n;
linebuflen -= n;
/* Get canonical name. */
n = strlen (tbuf) + 1; /* For the \0. */
if (__builtin_expect (n > linebuflen, 0))
goto too_small;
if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN)
{
++had_error;
continue;
}
result->h_name = bp;
bp = __mempcpy (bp, tbuf, n); /* Cannot overflow. */
linebuflen -= n;
continue;
}
if (qtype == T_PTR && type == T_CNAME)
{
n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf);
if (__builtin_expect (n < 0 || res_dnok (tbuf) == 0, 0))
{
++had_error;
continue;
}
cp += n;
/* Get canonical name. */
n = strlen (tbuf) + 1; /* For the \0. */
if (__builtin_expect (n > linebuflen, 0))
goto too_small;
if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN)
{
++had_error;
continue;
}
tname = bp;
bp = __mempcpy (bp, tbuf, n); /* Cannot overflow. */
linebuflen -= n;
continue;
}
if (__builtin_expect (type == T_SIG, 0)
|| __builtin_expect (type == T_KEY, 0)
|| __builtin_expect (type == T_NXT, 0))
{
/* We don't support DNSSEC yet. For now, ignore the record
and send a low priority message to syslog. */
syslog (LOG_DEBUG | LOG_AUTH,
"gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
qname, p_class (C_IN), p_type(qtype), p_type (type));
cp += n;
continue;
}
if (type == T_A && qtype == T_AAAA && map)
have_to_map = 1;
else if (__builtin_expect (type != qtype, 0))
{
syslog (LOG_NOTICE | LOG_AUTH,
"gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
qname, p_class (C_IN), p_type (qtype), p_type (type));
cp += n;
continue; /* XXX - had_error++ ? */
}
switch (type)
{
case T_PTR:
if (__builtin_expect (strcasecmp (tname, bp) != 0, 0))
{
syslog (LOG_NOTICE | LOG_AUTH, AskedForGot, qname, bp);
cp += n;
continue; /* XXX - had_error++ ? */
}
n = __ns_name_unpack (answer->buf, end_of_message, cp,
packtmp, sizeof packtmp);
if (n != -1 && __ns_name_ntop (packtmp, bp, linebuflen) == -1)
{
if (__builtin_expect (errno, 0) == EMSGSIZE)
goto too_small;
n = -1;
}
if (__builtin_expect (n < 0 || res_hnok (bp) == 0, 0))
{
++had_error;
break;
}
#if MULTI_PTRS_ARE_ALIASES
cp += n;
if (haveanswer == 0)
result->h_name = bp;
else if (ap < &host_data->aliases[MAXALIASES-1])
*ap++ = bp;
else
n = -1;
if (n != -1)
{
n = strlen (bp) + 1; /* for the \0 */
if (__builtin_expect (n, 0) >= MAXHOSTNAMELEN)
{
++had_error;
break;
}
bp += n;
linebuflen -= n;
}
break;
#else
result->h_name = bp;
if (have_to_map)
{
n = strlen (bp) + 1; /* for the \0 */
if (__builtin_expect (n >= MAXHOSTNAMELEN, 0))
{
++had_error;
break;
}
bp += n;
linebuflen -= n;
if (map_v4v6_hostent (result, &bp, &linebuflen))
goto too_small;
}
*h_errnop = NETDB_SUCCESS;
return NSS_STATUS_SUCCESS;
#endif
case T_A:
case T_AAAA:
if (__builtin_expect (strcasecmp (result->h_name, bp), 0) != 0)
{
syslog (LOG_NOTICE | LOG_AUTH, AskedForGot, result->h_name, bp);
cp += n;
continue; /* XXX - had_error++ ? */
}
if (n != result->h_length)
{
cp += n;
continue;
}
if (!haveanswer)
{
register int nn;
/* We compose a single hostent out of the entire chain of
entries, so the TTL of the hostent is essentially the lowest
TTL in the chain. */
if (ttlp != NULL && ttl < *ttlp)
*ttlp = ttl;
if (canonp != NULL)
*canonp = bp;
result->h_name = bp;
nn = strlen (bp) + 1; /* for the \0 */
bp += nn;
linebuflen -= nn;
}
linebuflen -= sizeof (align) - ((u_long) bp % sizeof (align));
bp += sizeof (align) - ((u_long) bp % sizeof (align));
if (__builtin_expect (n > linebuflen, 0))
goto too_small;
bp = __mempcpy (*hap++ = bp, cp, n);
cp += n;
linebuflen -= n;
break;
default:
abort ();
}
if (had_error == 0)
++haveanswer;
}
if (haveanswer > 0)
{
*ap = NULL;
*hap = NULL;
#if defined RESOLVSORT
/*
* Note: we sort even if host can take only one address
* in its return structures - should give it the "best"
* address in that case, not some random one
*/
if (_res.nsort && haveanswer > 1 && qtype == T_A)
addrsort (host_data->h_addr_ptrs, haveanswer);
#endif /*RESOLVSORT*/
if (result->h_name == NULL)
{
n = strlen (qname) + 1; /* For the \0. */
if (n > linebuflen)
goto too_small;
if (n >= MAXHOSTNAMELEN)
goto no_recovery;
result->h_name = bp;
bp = __mempcpy (bp, qname, n); /* Cannot overflow. */
linebuflen -= n;
}
if (have_to_map)
if (map_v4v6_hostent (result, &bp, &linebuflen))
goto too_small;
*h_errnop = NETDB_SUCCESS;
return NSS_STATUS_SUCCESS;
}
no_recovery:
*h_errnop = NO_RECOVERY;
*errnop = ENOENT;
/* Special case here: if the resolver sent a result but it only
contains a CNAME while we are looking for a T_A or T_AAAA record,
we fail with NOTFOUND instead of TRYAGAIN. */
return ((qtype == T_A || qtype == T_AAAA) && ap != host_data->aliases
? NSS_STATUS_NOTFOUND : NSS_STATUS_TRYAGAIN);
}
static enum nss_status
gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname,
struct gaih_addrtuple ***patp,
char **bufferp, size_t *buflenp,
int *errnop, int *h_errnop, int32_t *ttlp, int *firstp)
{
char *buffer = *bufferp;
size_t buflen = *buflenp;
struct gaih_addrtuple **pat = *patp;
const HEADER *hp = &answer->hdr;
int ancount = ntohs (hp->ancount);
int qdcount = ntohs (hp->qdcount);
const u_char *cp = answer->buf + HFIXEDSZ;
const u_char *end_of_message = answer->buf + anslen;
if (__builtin_expect (qdcount != 1, 0))
{
*h_errnop = NO_RECOVERY;
return NSS_STATUS_UNAVAIL;
}
u_char packtmp[NS_MAXCDNAME];
int n = __ns_name_unpack (answer->buf, end_of_message, cp,
packtmp, sizeof packtmp);
/* We unpack the name to check it for validity. But we do not need
it later. */
if (n != -1 && __ns_name_ntop (packtmp, buffer, buflen) == -1)
{
if (__builtin_expect (errno, 0) == EMSGSIZE)
{
too_small:
*errnop = ERANGE;
*h_errnop = NETDB_INTERNAL;
return NSS_STATUS_TRYAGAIN;
}
n = -1;
}
if (__builtin_expect (n < 0 || (res_hnok (buffer) == 0
&& (errno = EBADMSG)), 0))
{
*errnop = errno;
*h_errnop = NO_RECOVERY;
return NSS_STATUS_UNAVAIL;
}
cp += n + QFIXEDSZ;
int haveanswer = 0;
int had_error = 0;
char *canon = NULL;
char *h_name = NULL;
int h_namelen = 0;
if (ancount == 0)
return NSS_STATUS_NOTFOUND;
while (ancount-- > 0 && cp < end_of_message && had_error == 0)
{
n = __ns_name_unpack (answer->buf, end_of_message, cp,
packtmp, sizeof packtmp);
if (n != -1 &&
(h_namelen = __ns_name_ntop (packtmp, buffer, buflen)) == -1)
{
if (__builtin_expect (errno, 0) == EMSGSIZE)
goto too_small;
n = -1;
}
if (__builtin_expect (n < 0 || res_hnok (buffer) == 0, 0))
{
++had_error;
continue;
}
if (*firstp && canon == NULL)
{
h_name = buffer;
buffer += h_namelen;
buflen -= h_namelen;
}
cp += n; /* name */
if (__builtin_expect (cp + 10 > end_of_message, 0))
{
++had_error;
continue;
}
int type = __ns_get16 (cp);
cp += INT16SZ; /* type */
int class = __ns_get16 (cp);
cp += INT16SZ; /* class */
int32_t ttl = __ns_get32 (cp);
cp += INT32SZ; /* TTL */
n = __ns_get16 (cp);
cp += INT16SZ; /* len */
if (class != C_IN)
{
cp += n;
continue;
}
if (type == T_CNAME)
{
char tbuf[MAXDNAME];
/* A CNAME could also have a TTL entry. */
if (ttlp != NULL && ttl < *ttlp)
*ttlp = ttl;
n = dn_expand (answer->buf, end_of_message, cp, tbuf, sizeof tbuf);
if (__builtin_expect (n < 0 || res_hnok (tbuf) == 0, 0))
{
++had_error;
continue;
}
cp += n;
if (*firstp)
{
/* Reclaim buffer space. */
if (h_name + h_namelen == buffer)
{
buffer = h_name;
buflen += h_namelen;
}
n = strlen (tbuf) + 1;
if (__builtin_expect (n > buflen, 0))
goto too_small;
if (__builtin_expect (n >= MAXHOSTNAMELEN, 0))
{
++had_error;
continue;
}
canon = buffer;
buffer = __mempcpy (buffer, tbuf, n);
buflen -= n;
h_namelen = 0;
}
continue;
}
#if 1
// We should not see any types other than those explicitly listed
// below. Some types sent by server seem missing, though. Just
// collect the data for now.
if (__builtin_expect (type != T_A && type != T_AAAA, 0))
#else
if (__builtin_expect (type == T_SIG, 0)
|| __builtin_expect (type == T_KEY, 0)
|| __builtin_expect (type == T_NXT, 0)
|| __builtin_expect (type == T_PTR, 0)
|| __builtin_expect (type == T_DNAME, 0))
#endif
{
/* We don't support DNSSEC yet. For now, ignore the record
and send a low priority message to syslog.
We also don't expect T_PTR or T_DNAME messages. */
syslog (LOG_DEBUG | LOG_AUTH,
"getaddrinfo*.gaih_getanswer: got type \"%s\"",
p_type (type));
cp += n;
continue;
}
if (type != T_A && type != T_AAAA)
abort ();
if (*pat == NULL)
{
uintptr_t pad = (-(uintptr_t) buffer
% __alignof__ (struct gaih_addrtuple));
buffer += pad;
buflen = buflen > pad ? buflen - pad : 0;
if (__builtin_expect (buflen < sizeof (struct gaih_addrtuple),
0))
goto too_small;
*pat = (struct gaih_addrtuple *) buffer;
buffer += sizeof (struct gaih_addrtuple);
buflen -= sizeof (struct gaih_addrtuple);
}
(*pat)->name = NULL;
(*pat)->next = NULL;
if (*firstp)
{
/* We compose a single hostent out of the entire chain of
entries, so the TTL of the hostent is essentially the lowest
TTL in the chain. */
if (ttlp != NULL && ttl < *ttlp)
*ttlp = ttl;
(*pat)->name = canon ?: h_name;
*firstp = 0;
}
(*pat)->family = type == T_A ? AF_INET : AF_INET6;
if (__builtin_expect ((type == T_A && n != INADDRSZ)
|| (type == T_AAAA && n != IN6ADDRSZ), 0))
{
++had_error;
continue;
}
memcpy ((*pat)->addr, cp, n);
cp += n;
(*pat)->scopeid = 0;
pat = &((*pat)->next);
haveanswer = 1;
}
if (haveanswer)
{
*patp = pat;
*bufferp = buffer;
*buflenp = buflen;
*h_errnop = NETDB_SUCCESS;
return NSS_STATUS_SUCCESS;
}
/* Special case here: if the resolver sent a result but it only
contains a CNAME while we are looking for a T_A or T_AAAA record,
we fail with NOTFOUND instead of TRYAGAIN. */
return canon == NULL ? NSS_STATUS_TRYAGAIN : NSS_STATUS_NOTFOUND;
}
static enum nss_status
gaih_getanswer (const querybuf *answer1, int anslen1, const querybuf *answer2,
int anslen2, const char *qname,
struct gaih_addrtuple **pat, char *buffer, size_t buflen,
int *errnop, int *h_errnop, int32_t *ttlp)
{
int first = 1;
enum nss_status status = NSS_STATUS_NOTFOUND;
if (anslen1 > 0)
status = gaih_getanswer_slice(answer1, anslen1, qname,
&pat, &buffer, &buflen,
errnop, h_errnop, ttlp,
&first);
if ((status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND
|| (status == NSS_STATUS_TRYAGAIN
/* We want to look at the second answer in case of an
NSS_STATUS_TRYAGAIN only if the error is non-recoverable, i.e.
*h_errnop is NO_RECOVERY. If not, and if the failure was due to
an insufficient buffer (ERANGE), then we need to drop the results
and pass on the NSS_STATUS_TRYAGAIN to the caller so that it can
repeat the query with a larger buffer. */
&& (*errnop != ERANGE || *h_errnop == NO_RECOVERY)))
&& answer2 != NULL && anslen2 > 0)
{
enum nss_status status2 = gaih_getanswer_slice(answer2, anslen2, qname,
&pat, &buffer, &buflen,
errnop, h_errnop, ttlp,
&first);
if (status != NSS_STATUS_SUCCESS && status2 != NSS_STATUS_NOTFOUND)
status = status2;
}
return status;
}
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