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glibc/resolv/nss_dns/dns-host.c
Andreas Schwab 6b142b3a1d Record TTL also for DNS PTR queries (bug 18513) 
This allows nscd to manage proper TTL for GETHOSTBYADDR[v6] requests.
2015-06-22 14:04:34 +02:00

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/* Copyright (C) 1996-2015 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
#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, NULL);
if (n < 0)
{
switch (errno)
{
case ESRCH:
status = NSS_STATUS_TRYAGAIN;
h_errno = TRY_AGAIN;
break;
/* System has run out of file descriptors. */
case EMFILE:
case ENFILE:
h_errno = NETDB_INTERNAL;
/* Fall through. */
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, 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 ans2p_malloced = 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, &ans2p_malloced);
if (n >= 0)
{
status = gaih_getanswer (host_buffer.buf, n, (const querybuf *) ans2p,
resplen2, name, pat, buffer, buflen,
errnop, herrnop, ttlp);
}
else
{
switch (errno)
{
case ESRCH:
status = NSS_STATUS_TRYAGAIN;
h_errno = TRY_AGAIN;
break;
/* System has run out of file descriptors. */
case EMFILE:
case ENFILE:
h_errno = NETDB_INTERNAL;
/* Fall through. */
case ECONNREFUSED:
case ETIMEDOUT:
status = NSS_STATUS_UNAVAIL;
break;
default:
status = NSS_STATUS_NOTFOUND;
break;
}
*herrnop = h_errno;
if (h_errno == TRY_AGAIN)
*errnop = EAGAIN;
else
__set_errno (olderr);
}
/* Check whether ans2p was separately allocated. */
if (ans2p_malloced)
free (ans2p);
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 (__glibc_unlikely (buflen < sizeof (struct host_data)))
{
*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 (__glibc_unlikely (_res.options & RES_USEBSTRING))
{
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, 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, 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, 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;
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;
buflen = buflen > pad ? buflen - pad : 0;
if (__glibc_unlikely (buflen < sizeof (struct host_data)))
{
/* 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 (__glibc_unlikely (n < 0 || (*name_ok) (bp) == 0))
{
++had_error;
continue;
}
cp += n; /* name */
if (__glibc_unlikely (cp + 10 > end_of_message))
{
++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 (__glibc_unlikely (class != C_IN))
{
/* 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 (__glibc_unlikely (n < 0 || (*name_ok) (tbuf) == 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 (__glibc_unlikely (n > linebuflen))
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)
{
/* 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 (__glibc_unlikely (n < 0 || res_dnok (tbuf) == 0))
{
++had_error;
continue;
}
cp += n;
/* Get canonical name. */
n = strlen (tbuf) + 1; /* For the \0. */
if (__glibc_unlikely (n > linebuflen))
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 (type == T_A && qtype == T_AAAA && map)
have_to_map = 1;
else if (__glibc_unlikely (type != qtype))
{
/* Log a low priority message if we get an unexpected record, but
skip it if we are using DNSSEC since it uses many different types
in responses that do not match QTYPE. */
if ((_res.options & RES_USE_DNSSEC) == 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 (__glibc_unlikely (strcasecmp (tname, bp) != 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 (__glibc_unlikely (n < 0 || res_hnok (bp) == 0))
{
++had_error;
break;
}
if (ttlp != NULL && ttl < *ttlp)
*ttlp = ttl;
/* bind would put multiple PTR records as aliases, but we don't do
that. */
result->h_name = bp;
if (have_to_map)
{
n = strlen (bp) + 1; /* for the \0 */
if (__glibc_unlikely (n >= MAXHOSTNAMELEN))
{
++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;
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)
{
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 (__glibc_unlikely (n > linebuflen))
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 (__glibc_unlikely (qdcount != 1))
{
*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 (__glibc_unlikely (n < 0 || res_hnok (buffer) == 0))
{
++had_error;
continue;
}
if (*firstp && canon == NULL)
{
h_name = buffer;
buffer += h_namelen;
buflen -= h_namelen;
}
cp += n; /* name */
if (__glibc_unlikely (cp + 10 > end_of_message))
{
++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 (__glibc_unlikely (n < 0 || res_hnok (tbuf) == 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 (__glibc_unlikely (n > buflen))
goto too_small;
if (__glibc_unlikely (n >= MAXHOSTNAMELEN))
{
++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 (__glibc_unlikely (type != T_A && type != T_AAAA))
#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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