/* Resolver state initialization and resolv.conf parsing.
Copyright (C) 1995-2017 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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/>. */
/*
* Copyright (c) 1985, 1989, 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.
*/
/*
* Portions Copyright (c) 1996-1999 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM 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 <ctype.h>
#include <netdb.h>
#include <resolv/resolv-internal.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <net/if.h>
#include <netinet/in.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <inet/net-internal.h>
#include <errno.h>
static void res_setoptions (res_state, const char *, const char *);
static uint32_t net_mask (struct in_addr);
unsigned long long int __res_initstamp attribute_hidden;
int
res_ninit (res_state statp)
{
return __res_vinit (statp, 0);
}
libc_hidden_def (__res_ninit)
/* Return true if CH separates the netmask in the "sortlist"
directive. */
static inline bool
is_sort_mask (char ch)
{
return ch == '/' || ch == '&';
}
/* Internal helper function for __res_vinit, to aid with resource
deallocation and error handling. Return true on success, false on
failure. */
static bool
res_vinit_1 (res_state statp, bool preinit, FILE *fp, char **buffer)
{
char *cp, **pp;
size_t buffer_size = 0;
int nserv = 0; /* Number of nameservers read from file. */
bool have_serv6 = false;
bool haveenv = false;
bool havesearch = false;
int nsort = 0;
char *net;
statp->_u._ext.initstamp = __res_initstamp;
if (!preinit)
{
statp->retrans = RES_TIMEOUT;
statp->retry = RES_DFLRETRY;
statp->options = RES_DEFAULT;
statp->id = res_randomid ();
}
statp->nscount = 0;
statp->defdname[0] = '\0';
statp->ndots = 1;
statp->pfcode = 0;
statp->_vcsock = -1;
statp->_flags = 0;
statp->__glibc_unused_qhook = NULL;
statp->__glibc_unused_rhook = NULL;
statp->_u._ext.nscount = 0;
for (int n = 0; n < MAXNS; n++)
statp->_u._ext.nsaddrs[n] = NULL;
/* Allow user to override the local domain definition. */
if ((cp = getenv ("LOCALDOMAIN")) != NULL)
{
strncpy (statp->defdname, cp, sizeof (statp->defdname) - 1);
statp->defdname[sizeof (statp->defdname) - 1] = '\0';
haveenv = true;
/* Set search list to be blank-separated strings from rest of
env value. Permits users of LOCALDOMAIN to still have a
search list, and anyone to set the one that they want to use
as an individual (even more important now that the rfc1535
stuff restricts searches). */
cp = statp->defdname;
pp = statp->dnsrch;
*pp++ = cp;
for (int n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++)
{
if (*cp == '\n')
break;
else if (*cp == ' ' || *cp == '\t')
{
*cp = 0;
n = 1;
}
else if (n > 0)
{
*pp++ = cp;
n = 0;
havesearch = true;
}
}
/* Null terminate last domain if there are excess. */
while (*cp != '\0' && *cp != ' ' && *cp != '\t' && *cp != '\n')
cp++;
*cp = '\0';
*pp++ = 0;
}
#define MATCH(line, name) \
(!strncmp ((line), name, sizeof (name) - 1) \
&& ((line)[sizeof (name) - 1] == ' ' \
|| (line)[sizeof (name) - 1] == '\t'))
if (fp != NULL)
{
/* No threads use this stream. */
__fsetlocking (fp, FSETLOCKING_BYCALLER);
/* Read the config file. */
while (true)
{
{
ssize_t ret = __getline (buffer, &buffer_size, fp);
if (ret <= 0)
{
if (_IO_ferror_unlocked (fp))
return false;
else
break;
}
}
/* Skip comments. */
if (**buffer == ';' || **buffer == '#')
continue;
/* Read default domain name. */
if (MATCH (*buffer, "domain"))
{
if (haveenv)
/* LOCALDOMAIN overrides the configuration file. */
continue;
cp = *buffer + sizeof ("domain") - 1;
while (*cp == ' ' || *cp == '\t')
cp++;
if ((*cp == '\0') || (*cp == '\n'))
continue;
strncpy (statp->defdname, cp, sizeof (statp->defdname) - 1);
statp->defdname[sizeof (statp->defdname) - 1] = '\0';
if ((cp = strpbrk (statp->defdname, " \t\n")) != NULL)
*cp = '\0';
havesearch = false;
continue;
}
/* Set search list. */
if (MATCH (*buffer, "search"))
{
if (haveenv)
/* LOCALDOMAIN overrides the configuration file. */
continue;
cp = *buffer + sizeof ("search") - 1;
while (*cp == ' ' || *cp == '\t')
cp++;
if ((*cp == '\0') || (*cp == '\n'))
continue;
strncpy (statp->defdname, cp, sizeof (statp->defdname) - 1);
statp->defdname[sizeof (statp->defdname) - 1] = '\0';
if ((cp = strchr (statp->defdname, '\n')) != NULL)
*cp = '\0';
/* Set search list to be blank-separated strings on rest
of line. */
cp = statp->defdname;
pp = statp->dnsrch;
*pp++ = cp;
for (int n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++)
{
if (*cp == ' ' || *cp == '\t')
{
*cp = 0;
n = 1;
}
else if (n)
{
*pp++ = cp;
n = 0;
}
}
/* Null terminate last domain if there are excess. */
while (*cp != '\0' && *cp != ' ' && *cp != '\t')
cp++;
*cp = '\0';
*pp++ = 0;
havesearch = true;
continue;
}
/* Read nameservers to query. */
if (MATCH (*buffer, "nameserver") && nserv < MAXNS)
{
struct in_addr a;
cp = *buffer + sizeof ("nameserver") - 1;
while (*cp == ' ' || *cp == '\t')
cp++;
if ((*cp != '\0') && (*cp != '\n') && __inet_aton (cp, &a))
{
statp->nsaddr_list[nserv].sin_addr = a;
statp->nsaddr_list[nserv].sin_family = AF_INET;
statp->nsaddr_list[nserv].sin_port = htons (NAMESERVER_PORT);
nserv++;
}
else
{
struct in6_addr a6;
char *el;
if ((el = strpbrk (cp, " \t\n")) != NULL)
*el = '\0';
if ((el = strchr (cp, SCOPE_DELIMITER)) != NULL)
*el = '\0';
if ((*cp != '\0') && (__inet_pton (AF_INET6, cp, &a6) > 0))
{
struct sockaddr_in6 *sa6;
sa6 = malloc (sizeof (*sa6));
if (sa6 == NULL)
return false;
sa6->sin6_family = AF_INET6;
sa6->sin6_port = htons (NAMESERVER_PORT);
sa6->sin6_flowinfo = 0;
sa6->sin6_addr = a6;
sa6->sin6_scope_id = 0;
if (__glibc_likely (el != NULL))
/* Ignore errors, for backwards
compatibility. */
__inet6_scopeid_pton
(&a6, el + 1, &sa6->sin6_scope_id);
statp->nsaddr_list[nserv].sin_family = 0;
statp->_u._ext.nsaddrs[nserv] = sa6;
statp->_u._ext.nssocks[nserv] = -1;
have_serv6 = true;
nserv++;
}
}
continue;
}
if (MATCH (*buffer, "sortlist"))
{
struct in_addr a;
cp = *buffer + sizeof ("sortlist") - 1;
while (nsort < MAXRESOLVSORT)
{
while (*cp == ' ' || *cp == '\t')
cp++;
if (*cp == '\0' || *cp == '\n' || *cp == ';')
break;
net = cp;
while (*cp && !is_sort_mask (*cp) && *cp != ';'
&& isascii (*cp) && !isspace (*cp))
cp++;
char separator = *cp;
*cp = 0;
if (__inet_aton (net, &a))
{
statp->sort_list[nsort].addr = a;
if (is_sort_mask (separator))
{
*cp++ = separator;
net = cp;
while (*cp && *cp != ';'
&& isascii (*cp) && !isspace (*cp))
cp++;
separator = *cp;
*cp = 0;
if (__inet_aton (net, &a))
statp->sort_list[nsort].mask = a.s_addr;
else
statp->sort_list[nsort].mask
= net_mask (statp->sort_list[nsort].addr);
}
else
statp->sort_list[nsort].mask
= net_mask (statp->sort_list[nsort].addr);
nsort++;
}
*cp = separator;
}
continue;
}
if (MATCH (*buffer, "options"))
{
res_setoptions (statp, *buffer + sizeof ("options") - 1, "conf");
continue;
}
}
statp->nscount = nserv;
if (have_serv6)
/* We try IPv6 servers again. */
statp->ipv6_unavail = false;
statp->nsort = nsort;
fclose (fp);
}
if (__glibc_unlikely (statp->nscount == 0))
{
statp->nsaddr.sin_addr = __inet_makeaddr (IN_LOOPBACKNET, 1);
statp->nsaddr.sin_family = AF_INET;
statp->nsaddr.sin_port = htons (NAMESERVER_PORT);
statp->nscount = 1;
}
if (statp->defdname[0] == 0)
{
char buf[sizeof (statp->defdname)];
if (__gethostname (buf, sizeof (statp->defdname) - 1) == 0
&& (cp = strchr (buf, '.')) != NULL)
strcpy (statp->defdname, cp + 1);
}
/* Find components of local domain that might be searched. */
if (!havesearch)
{
pp = statp->dnsrch;
*pp++ = statp->defdname;
*pp = NULL;
}
if ((cp = getenv ("RES_OPTIONS")) != NULL)
res_setoptions (statp, cp, "env");
statp->options |= RES_INIT;
return true;
}
/* Set up default settings. If the /etc/resolv.conf configuration
file exist, the values there will have precedence. Otherwise, the
server address is set to INADDR_LOOPBACK and the default domain
name comes from gethostname. The RES_OPTIONS and LOCALDOMAIN
environment variables can be used to override some settings.
Return 0 if completes successfully, -1 on error. */
int
__res_vinit (res_state statp, int preinit)
{
FILE *fp = fopen (_PATH_RESCONF, "rce");
if (fp == NULL)
switch (errno)
{
case EACCES:
case EISDIR:
case ELOOP:
case ENOENT:
case ENOTDIR:
case EPERM:
/* Ignore these errors. They are persistent errors caused
by file system contents. */
break;
default:
/* Other errors refer to resource allocation problems and
need to be handled by the application. */
return -1;
}
char *buffer = NULL;
bool ok = res_vinit_1 (statp, preinit, fp, &buffer);
free (buffer);
if (!ok)
{
/* Deallocate the name server addresses which have been
allocated. */
for (int n = 0; n < MAXNS; n++)
free (statp->_u._ext.nsaddrs[n]);
return -1;
}
return 0;
}
static void
res_setoptions (res_state statp, const char *options, const char *source)
{
const char *cp = options;
while (*cp)
{
/* Skip leading and inner runs of spaces. */
while (*cp == ' ' || *cp == '\t')
cp++;
/* Search for and process individual options. */
if (!strncmp (cp, "ndots:", sizeof ("ndots:") - 1))
{
int i = atoi (cp + sizeof ("ndots:") - 1);
if (i <= RES_MAXNDOTS)
statp->ndots = i;
else
statp->ndots = RES_MAXNDOTS;
}
else if (!strncmp (cp, "timeout:", sizeof ("timeout:") - 1))
{
int i = atoi (cp + sizeof ("timeout:") - 1);
if (i <= RES_MAXRETRANS)
statp->retrans = i;
else
statp->retrans = RES_MAXRETRANS;
}
else if (!strncmp (cp, "attempts:", sizeof ("attempts:") - 1))
{
int i = atoi (cp + sizeof ("attempts:") - 1);
if (i <= RES_MAXRETRY)
statp->retry = i;
else
statp->retry = RES_MAXRETRY;
}
else
{
static const struct
{
char str[22];
uint8_t len;
uint8_t clear;
unsigned long int flag;
} options[] = {
#define STRnLEN(str) str, sizeof (str) - 1
{ STRnLEN ("inet6"), 0, DEPRECATED_RES_USE_INET6 },
{ STRnLEN ("rotate"), 0, RES_ROTATE },
{ STRnLEN ("edns0"), 0, RES_USE_EDNS0 },
{ STRnLEN ("single-request-reopen"), 0, RES_SNGLKUPREOP },
{ STRnLEN ("single-request"), 0, RES_SNGLKUP },
{ STRnLEN ("no_tld_query"), 0, RES_NOTLDQUERY },
{ STRnLEN ("no-tld-query"), 0, RES_NOTLDQUERY },
{ STRnLEN ("use-vc"), 0, RES_USEVC }
};
#define noptions (sizeof (options) / sizeof (options[0]))
for (int i = 0; i < noptions; ++i)
if (strncmp (cp, options[i].str, options[i].len) == 0)
{
if (options[i].clear)
statp->options &= options[i].flag;
else
statp->options |= options[i].flag;
break;
}
}
/* Skip to next run of spaces. */
while (*cp && *cp != ' ' && *cp != '\t')
cp++;
}
}
static uint32_t
net_mask (struct in_addr in)
{
uint32_t i = ntohl (in.s_addr);
if (IN_CLASSA (i))
return htonl (IN_CLASSA_NET);
else if (IN_CLASSB (i))
return htonl (IN_CLASSB_NET);
return htonl (IN_CLASSC_NET);
}