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glibc/resolv/res_init.c
Ross Lagerwall ad8ac1bd6a Open /etc/resolv.conf with FD_CLOEXEC
2011-12-17 14:43:40 -05:00

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/*
* 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static const char sccsid[] = "@(#)res_init.c 8.1 (Berkeley) 6/7/93";
static const char rcsid[] = "$BINDId: res_init.c,v 8.16 2000/05/09 07:10:12 vixie Exp $";
#endif /* LIBC_SCCS and not lint */
#include <ctype.h>
#include <netdb.h>
#include <resolv.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.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 <not-cancel.h>
/* Options. Should all be left alone. */
#define RESOLVSORT
#define RFC1535
/* #undef DEBUG */
static void res_setoptions (res_state, const char *, const char *)
internal_function;
#ifdef RESOLVSORT
static const char sort_mask_chars[] = "/&";
#define ISSORTMASK(ch) (strchr(sort_mask_chars, ch) != NULL)
static u_int32_t net_mask (struct in_addr) __THROW;
#endif
#if !defined(isascii) /* XXX - could be a function */
# define isascii(c) (!(c & 0200))
#endif
#ifdef _LIBC
unsigned long long int __res_initstamp attribute_hidden;
#endif
/*
* Resolver state default settings.
*/
/*
* Set up default settings. If the configuration file exist, the values
* there will have precedence. Otherwise, the server address is set to
* INADDR_ANY and the default domain name comes from the gethostname().
*
* An interrim version of this code (BIND 4.9, pre-4.4BSD) used 127.0.0.1
* rather than INADDR_ANY ("0.0.0.0") as the default name server address
* since it was noted that INADDR_ANY actually meant ``the first interface
* you "ifconfig"'d at boot time'' and if this was a SLIP or PPP interface,
* it had to be "up" in order for you to reach your own name server. It
* was later decided that since the recommended practice is to always
* install local static routes through 127.0.0.1 for all your network
* interfaces, that we could solve this problem without a code change.
*
* The configuration file should always be used, since it is the only way
* to specify a default domain. If you are running a server on your local
* machine, you should say "nameserver 0.0.0.0" or "nameserver 127.0.0.1"
* in the configuration file.
*
* Return 0 if completes successfully, -1 on error
*/
int
res_ninit(res_state statp) {
extern int __res_vinit(res_state, int);
return (__res_vinit(statp, 0));
}
#ifdef _LIBC
libc_hidden_def (__res_ninit)
#endif
/* This function has to be reachable by res_data.c but not publically. */
int
__res_vinit(res_state statp, int preinit) {
register FILE *fp;
register char *cp, **pp;
register int n;
char buf[BUFSIZ];
int nserv = 0; /* number of nameserver records read from file */
#ifdef _LIBC
int nservall = 0; /* number of NS records read, nserv IPv4 only */
#endif
int haveenv = 0;
int havesearch = 0;
#ifdef RESOLVSORT
int nsort = 0;
char *net;
#endif
#ifndef RFC1535
int dots;
#endif
#ifdef _LIBC
statp->_u._ext.initstamp = __res_initstamp;
#endif
if (!preinit) {
statp->retrans = RES_TIMEOUT;
statp->retry = RES_DFLRETRY;
statp->options = RES_DEFAULT;
statp->id = res_randomid();
}
statp->nscount = 0;
statp->ndots = 1;
statp->pfcode = 0;
statp->_vcsock = -1;
statp->_flags = 0;
statp->qhook = NULL;
statp->rhook = NULL;
statp->_u._ext.nsinit = 0;
statp->_u._ext.nscount = 0;
#ifdef _LIBC
statp->_u._ext.nscount6 = 0;
for (n = 0; n < MAXNS; n++) {
statp->_u._ext.nsaddrs[n] = NULL;
statp->_u._ext.nsmap[n] = MAXNS;
}
#endif
/* Allow user to override the local domain definition */
if ((cp = getenv("LOCALDOMAIN")) != NULL) {
(void)strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
statp->defdname[sizeof(statp->defdname) - 1] = '\0';
haveenv++;
/*
* 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 (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
if (*cp == '\n') /* silly backwards compat */
break;
else if (*cp == ' ' || *cp == '\t') {
*cp = 0;
n = 1;
} else if (n) {
*pp++ = cp;
n = 0;
havesearch = 1;
}
}
/* 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 = fopen(_PATH_RESCONF, "rce")) != NULL) {
/* No threads use this stream. */
__fsetlocking (fp, FSETLOCKING_BYCALLER);
/* read the config file */
while (fgets_unlocked(buf, sizeof(buf), fp) != NULL) {
/* skip comments */
if (*buf == ';' || *buf == '#')
continue;
/* read default domain name */
if (MATCH(buf, "domain")) {
if (haveenv) /* skip if have from environ */
continue;
cp = buf + 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 = 0;
continue;
}
/* set search list */
if (MATCH(buf, "search")) {
if (haveenv) /* skip if have from environ */
continue;
cp = buf + 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 (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 = 1;
continue;
}
/* read nameservers to query */
#ifdef _LIBC
if (MATCH(buf, "nameserver") && nservall < MAXNS) {
#else
if (MATCH(buf, "nameserver") && nserv < MAXNS) {
#endif
struct in_addr a;
cp = buf + sizeof("nameserver") - 1;
while (*cp == ' ' || *cp == '\t')
cp++;
if ((*cp != '\0') && (*cp != '\n')
&& __inet_aton(cp, &a)) {
statp->nsaddr_list[nservall].sin_addr = a;
statp->nsaddr_list[nservall].sin_family = AF_INET;
statp->nsaddr_list[nservall].sin_port =
htons(NAMESERVER_PORT);
nserv++;
#ifdef _LIBC
nservall++;
} 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) {
sa6->sin6_family = AF_INET6;
sa6->sin6_port = htons(NAMESERVER_PORT);
sa6->sin6_flowinfo = 0;
sa6->sin6_addr = a6;
if (__builtin_expect (el == NULL, 1))
sa6->sin6_scope_id = 0;
else {
int try_numericscope = 1;
if (IN6_IS_ADDR_LINKLOCAL (&a6)
|| IN6_IS_ADDR_MC_LINKLOCAL (&a6)) {
sa6->sin6_scope_id
= if_nametoindex (el + 1);
if (sa6->sin6_scope_id != 0)
try_numericscope = 0;
}
if (try_numericscope) {
char *end;
sa6->sin6_scope_id
= (uint32_t) strtoul (el + 1, &end,
10);
if (*end != '\0')
sa6->sin6_scope_id = 0;
}
}
statp->_u._ext.nsaddrs[nservall] = sa6;
statp->_u._ext.nssocks[nservall] = -1;
statp->_u._ext.nsmap[nservall] = MAXNS + 1;
nservall++;
}
}
#endif
}
continue;
}
#ifdef RESOLVSORT
if (MATCH(buf, "sortlist")) {
struct in_addr a;
cp = buf + sizeof("sortlist") - 1;
while (nsort < MAXRESOLVSORT) {
while (*cp == ' ' || *cp == '\t')
cp++;
if (*cp == '\0' || *cp == '\n' || *cp == ';')
break;
net = cp;
while (*cp && !ISSORTMASK(*cp) && *cp != ';' &&
isascii(*cp) && !isspace(*cp))
cp++;
n = *cp;
*cp = 0;
if (__inet_aton(net, &a)) {
statp->sort_list[nsort].addr = a;
if (ISSORTMASK(n)) {
*cp++ = n;
net = cp;
while (*cp && *cp != ';' &&
isascii(*cp) && !isspace(*cp))
cp++;
n = *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 = n;
}
continue;
}
#endif
if (MATCH(buf, "options")) {
res_setoptions(statp, buf + sizeof("options") - 1, "conf");
continue;
}
}
statp->nscount = nservall;
#ifdef _LIBC
if (nservall - nserv > 0) {
statp->_u._ext.nscount6 = nservall - nserv;
/* We try IPv6 servers again. */
statp->ipv6_unavail = false;
}
#endif
#ifdef RESOLVSORT
statp->nsort = nsort;
#endif
(void) fclose(fp);
}
if (__builtin_expect(statp->nscount == 0, 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 &&
__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 == 0) {
pp = statp->dnsrch;
*pp++ = statp->defdname;
*pp = NULL;
#ifndef RFC1535
dots = 0;
for (cp = statp->defdname; *cp; cp++)
dots += (*cp == '.');
cp = statp->defdname;
while (pp < statp->dnsrch + MAXDFLSRCH) {
if (dots < LOCALDOMAINPARTS)
break;
cp = __rawmemchr(cp, '.') + 1; /* we know there is one */
*pp++ = cp;
dots--;
}
*pp = NULL;
#ifdef DEBUG
if (statp->options & RES_DEBUG) {
printf(";; res_init()... default dnsrch list:\n");
for (pp = statp->dnsrch; *pp; pp++)
printf(";;\t%s\n", *pp);
printf(";;\t..END..\n");
}
#endif
#endif /* !RFC1535 */
}
if ((cp = getenv("RES_OPTIONS")) != NULL)
res_setoptions(statp, cp, "env");
statp->options |= RES_INIT;
return (0);
}
static void
internal_function
res_setoptions(res_state statp, const char *options, const char *source) {
const char *cp = options;
int i;
#ifdef DEBUG
if (statp->options & RES_DEBUG)
printf(";; res_setoptions(\"%s\", \"%s\")...\n",
options, source);
#endif
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)) {
i = atoi(cp + sizeof("ndots:") - 1);
if (i <= RES_MAXNDOTS)
statp->ndots = i;
else
statp->ndots = RES_MAXNDOTS;
#ifdef DEBUG
if (statp->options & RES_DEBUG)
printf(";;\tndots=%d\n", statp->ndots);
#endif
} else if (!strncmp(cp, "timeout:", sizeof("timeout:") - 1)) {
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)){
i = atoi(cp + sizeof("attempts:") - 1);
if (i <= RES_MAXRETRY)
statp->retry = i;
else
statp->retry = RES_MAXRETRY;
} else if (!strncmp(cp, "debug", sizeof("debug") - 1)) {
#ifdef DEBUG
if (!(statp->options & RES_DEBUG)) {
printf(";; res_setoptions(\"%s\", \"%s\")..\n",
options, source);
statp->options |= RES_DEBUG;
}
printf(";;\tdebug\n");
#endif
} 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, RES_USE_INET6 },
{ STRnLEN ("ip6-bytestring"), 0, RES_USEBSTRING },
{ STRnLEN ("no-ip6-dotint"), 0, RES_NOIP6DOTINT },
{ STRnLEN ("ip6-dotint"), 1, ~RES_NOIP6DOTINT },
{ STRnLEN ("rotate"), 0, RES_ROTATE },
{ STRnLEN ("no-check-names"), 0, RES_NOCHECKNAME },
{ 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]))
int i;
for (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;
}
if (i == noptions) {
/* XXX - print a warning here? */
}
}
/* skip to next run of spaces */
while (*cp && *cp != ' ' && *cp != '\t')
cp++;
}
}
#ifdef RESOLVSORT
/* XXX - should really support CIDR which means explicit masks always. */
static u_int32_t
net_mask(in) /* XXX - should really use system's version of this */
struct in_addr in;
{
register u_int32_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));
}
#endif
u_int
res_randomid(void) {
return 0xffff & __getpid();
}
#ifdef _LIBC
libc_hidden_def (__res_randomid)
#endif
/*
* This routine is for closing the socket if a virtual circuit is used and
* the program wants to close it. This provides support for endhostent()
* which expects to close the socket.
*
* This routine is not expected to be user visible.
*/
void
__res_iclose(res_state statp, bool free_addr) {
int ns;
if (statp->_vcsock >= 0) {
close_not_cancel_no_status(statp->_vcsock);
statp->_vcsock = -1;
statp->_flags &= ~(RES_F_VC | RES_F_CONN);
}
#ifdef _LIBC
for (ns = 0; ns < MAXNS; ns++)
#else
for (ns = 0; ns < statp->_u._ext.nscount; ns++)
#endif
if (statp->_u._ext.nsaddrs[ns]) {
if (statp->_u._ext.nssocks[ns] != -1) {
close_not_cancel_no_status(statp->_u._ext.nssocks[ns]);
statp->_u._ext.nssocks[ns] = -1;
}
if (free_addr) {
free (statp->_u._ext.nsaddrs[ns]);
statp->_u._ext.nsaddrs[ns] = NULL;
}
}
statp->_u._ext.nsinit = 0;
}
libc_hidden_def (__res_iclose)
void
res_nclose(res_state statp)
{
__res_iclose (statp, true);
}
#ifdef _LIBC
libc_hidden_def (__res_nclose)
#endif
#ifdef _LIBC
# ifdef _LIBC_REENTRANT
/* This is called when a thread is exiting to free resources held in _res. */
static void __attribute__ ((section ("__libc_thread_freeres_fn")))
res_thread_freeres (void)
{
if (_res.nscount == 0)
/* Never called res_ninit. */
return;
__res_iclose (&_res, true); /* Close any VC sockets. */
/* Make sure we do a full re-initialization the next time. */
_res.options = 0;
}
text_set_element (__libc_thread_subfreeres, res_thread_freeres);
text_set_element (__libc_subfreeres, res_thread_freeres);
# endif
#endif
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