freebsd-dev/lib/libc/net/gethostbynis.c
Brian Feldman 33dee81933 Make the resolver(3) and many associated interfaces much more reentrant.
The getaddrinfo(3), getipnodebyname(3) and resolver(3) can coincide now
with what should be totally reentrant, and h_errno values will now
be preserved correctly, but this does not affect interfaces such as
gethostbyname(3) which are still mostly non-reentrant.

In all of these relevant functions, the thread-safety has been pushed
down as far as it seems possible right now.  This means that operations
that are selected via nsdispatch(3) (i.e. files, yp, dns) are protected
still under global locks that getaddrinfo(3) defines, but where possible
the locking is greatly reduced.  The most noticeable improvement is
that multiple DNS lookups can now be run at the same time, and this
shows major improvement in performance of DNS-lookup threaded programs,
and solves the "Mozilla tab serialization" problem.

No single-threaded applications need to be recompiled.  Multi-threaded
applications that reference "_res" to change resolver(3) options will
need to be recompiled, and ones which reference "h_errno" will also
if they desire the correct h_errno values.  If the applications already
understood that _res and h_errno were not thread-safe and had their own
locking, they will see no performance improvement but will not
actually break in any way.

Please note that when NSS modules are used, or when nsdispatch(3)
defaults to adding any lookups of its own to the individual libc
_nsdispatch() calls, those MUST be reentrant as well.
2004-02-25 21:03:46 +00:00

191 lines
4.5 KiB
C

/*-
* Copyright (c) 1994, Garrett Wollman
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <errno.h>
#include <string.h>
#include <stdarg.h>
#include <nsswitch.h>
#ifdef YP
#include <rpc/rpc.h>
#include <rpcsvc/yp_prot.h>
#include <rpcsvc/ypclnt.h>
#endif
#define MAXALIASES 35
#define MAXADDRS 35
#ifdef YP
static char *host_aliases[MAXALIASES];
static char hostaddr[MAXADDRS];
static char *host_addrs[2];
static struct hostent *
_gethostbynis(name, map, af)
const char *name;
char *map;
int af;
{
char *cp, **q;
char *result;
int resultlen,size;
static struct hostent h;
static char *domain = (char *)NULL;
static char ypbuf[YPMAXRECORD + 2];
in_addr_t addr;
switch(af) {
case AF_INET:
size = NS_INADDRSZ;
break;
default:
case AF_INET6:
size = NS_IN6ADDRSZ;
errno = EAFNOSUPPORT;
h_errno = NETDB_INTERNAL;
return NULL;
}
if (domain == (char *)NULL)
if (yp_get_default_domain (&domain)) {
h_errno = NETDB_INTERNAL;
return ((struct hostent *)NULL);
}
if (yp_match(domain, map, name, strlen(name), &result, &resultlen)) {
h_errno = HOST_NOT_FOUND;
return ((struct hostent *)NULL);
}
/* avoid potential memory leak */
bcopy((char *)result, (char *)&ypbuf, resultlen);
ypbuf[resultlen] = '\0';
free(result);
result = (char *)&ypbuf;
if ((cp = index(result, '\n')))
*cp = '\0';
cp = strpbrk(result, " \t");
*cp++ = '\0';
h.h_addr_list = host_addrs;
h.h_addr = hostaddr;
addr = inet_addr(result);
bcopy((char *)&addr, h.h_addr, size);
h.h_length = size;
h.h_addrtype = AF_INET;
while (*cp == ' ' || *cp == '\t')
cp++;
h.h_name = cp;
q = h.h_aliases = host_aliases;
cp = strpbrk(cp, " \t");
if (cp != NULL)
*cp++ = '\0';
while (cp && *cp) {
if (*cp == ' ' || *cp == '\t') {
cp++;
continue;
}
if (q < &host_aliases[MAXALIASES - 1])
*q++ = cp;
cp = strpbrk(cp, " \t");
if (cp != NULL)
*cp++ = '\0';
}
*q = NULL;
return (&h);
}
#endif /* YP */
/* XXX _gethostbynisname/_gethostbynisaddr only used by getaddrinfo */
struct hostent *
_gethostbynisname(const char *name, int af)
{
#ifdef YP
return _gethostbynis(name, "hosts.byname", af);
#else
return NULL;
#endif
}
struct hostent *
_gethostbynisaddr(const char *addr, int len, int af)
{
#ifdef YP
return _gethostbynis(inet_ntoa(*(struct in_addr *)addr),
"hosts.byaddr", af);
#else
return NULL;
#endif
}
int
_nis_gethostbyname(void *rval, void *cb_data, va_list ap)
{
#ifdef YP
const char *name;
int af;
name = va_arg(ap, const char *);
af = va_arg(ap, int);
*(struct hostent **)rval = _gethostbynis(name, "hosts.byname", af);
return (*(struct hostent **)rval != NULL) ? NS_SUCCESS : NS_NOTFOUND;
#else
return NS_UNAVAIL;
#endif
}
int
_nis_gethostbyaddr(void *rval, void *cb_data, va_list ap)
{
#ifdef YP
const char *addr;
int len;
int af;
addr = va_arg(ap, const char *);
len = va_arg(ap, int);
af = va_arg(ap, int);
*(struct hostent **)rval =_gethostbynis(inet_ntoa(*(struct in_addr *)addr),"hosts.byaddr", af);
return (*(struct hostent **)rval != NULL) ? NS_SUCCESS : NS_NOTFOUND;
#else
return NS_UNAVAIL;
#endif
}