168 lines
3.6 KiB
C
168 lines
3.6 KiB
C
/*
|
|
* fs/cifs/dns_resolve.c
|
|
*
|
|
* Copyright (c) 2007 Igor Mammedov
|
|
* Author(s): Igor Mammedov (niallain@gmail.com)
|
|
* Steve French (sfrench@us.ibm.com)
|
|
*
|
|
* Contains the CIFS DFS upcall routines used for hostname to
|
|
* IP address translation.
|
|
*
|
|
* This 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.
|
|
*
|
|
* This 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 this library; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
*/
|
|
|
|
#include <keys/user-type.h>
|
|
#include "dns_resolve.h"
|
|
#include "cifsglob.h"
|
|
#include "cifsproto.h"
|
|
#include "cifs_debug.h"
|
|
|
|
/* Checks if supplied name is IP address
|
|
* returns:
|
|
* 1 - name is IP
|
|
* 0 - name is not IP
|
|
*/
|
|
static int
|
|
is_ip(char *name)
|
|
{
|
|
struct sockaddr_storage ss;
|
|
|
|
return cifs_convert_address(name, &ss);
|
|
}
|
|
|
|
static int
|
|
dns_resolver_instantiate(struct key *key, const void *data,
|
|
size_t datalen)
|
|
{
|
|
int rc = 0;
|
|
char *ip;
|
|
|
|
ip = kmalloc(datalen + 1, GFP_KERNEL);
|
|
if (!ip)
|
|
return -ENOMEM;
|
|
|
|
memcpy(ip, data, datalen);
|
|
ip[datalen] = '\0';
|
|
|
|
/* make sure this looks like an address */
|
|
if (!is_ip(ip)) {
|
|
kfree(ip);
|
|
return -EINVAL;
|
|
}
|
|
|
|
key->type_data.x[0] = datalen;
|
|
key->payload.data = ip;
|
|
|
|
return rc;
|
|
}
|
|
|
|
static void
|
|
dns_resolver_destroy(struct key *key)
|
|
{
|
|
kfree(key->payload.data);
|
|
}
|
|
|
|
struct key_type key_type_dns_resolver = {
|
|
.name = "dns_resolver",
|
|
.def_datalen = sizeof(struct in_addr),
|
|
.describe = user_describe,
|
|
.instantiate = dns_resolver_instantiate,
|
|
.destroy = dns_resolver_destroy,
|
|
.match = user_match,
|
|
};
|
|
|
|
/* Resolves server name to ip address.
|
|
* input:
|
|
* unc - server UNC
|
|
* output:
|
|
* *ip_addr - pointer to server ip, caller responcible for freeing it.
|
|
* return 0 on success
|
|
*/
|
|
int
|
|
dns_resolve_server_name_to_ip(const char *unc, char **ip_addr)
|
|
{
|
|
int rc = -EAGAIN;
|
|
struct key *rkey = ERR_PTR(-EAGAIN);
|
|
char *name;
|
|
char *data = NULL;
|
|
int len;
|
|
|
|
if (!ip_addr || !unc)
|
|
return -EINVAL;
|
|
|
|
/* search for server name delimiter */
|
|
len = strlen(unc);
|
|
if (len < 3) {
|
|
cFYI(1, ("%s: unc is too short: %s", __func__, unc));
|
|
return -EINVAL;
|
|
}
|
|
len -= 2;
|
|
name = memchr(unc+2, '\\', len);
|
|
if (!name) {
|
|
cFYI(1, ("%s: probably server name is whole unc: %s",
|
|
__func__, unc));
|
|
} else {
|
|
len = (name - unc) - 2/* leading // */;
|
|
}
|
|
|
|
name = kmalloc(len+1, GFP_KERNEL);
|
|
if (!name) {
|
|
rc = -ENOMEM;
|
|
return rc;
|
|
}
|
|
memcpy(name, unc+2, len);
|
|
name[len] = 0;
|
|
|
|
if (is_ip(name)) {
|
|
cFYI(1, ("%s: it is IP, skipping dns upcall: %s",
|
|
__func__, name));
|
|
data = name;
|
|
goto skip_upcall;
|
|
}
|
|
|
|
rkey = request_key(&key_type_dns_resolver, name, "");
|
|
if (!IS_ERR(rkey)) {
|
|
len = rkey->type_data.x[0];
|
|
data = rkey->payload.data;
|
|
} else {
|
|
cERROR(1, ("%s: unable to resolve: %s", __func__, name));
|
|
goto out;
|
|
}
|
|
|
|
skip_upcall:
|
|
if (data) {
|
|
*ip_addr = kmalloc(len + 1, GFP_KERNEL);
|
|
if (*ip_addr) {
|
|
memcpy(*ip_addr, data, len + 1);
|
|
if (!IS_ERR(rkey))
|
|
cFYI(1, ("%s: resolved: %s to %s", __func__,
|
|
name,
|
|
*ip_addr
|
|
));
|
|
rc = 0;
|
|
} else {
|
|
rc = -ENOMEM;
|
|
}
|
|
if (!IS_ERR(rkey))
|
|
key_put(rkey);
|
|
}
|
|
|
|
out:
|
|
kfree(name);
|
|
return rc;
|
|
}
|
|
|
|
|