2 * fs/cifs/dns_resolve.c
4 * Copyright (c) 2007 Igor Mammedov
5 * Author(s): Igor Mammedov (niallain@gmail.com)
6 * Steve French (sfrench@us.ibm.com)
8 * Contains the CIFS DFS upcall routines used for hostname to
9 * IP address translation.
11 * This library is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU Lesser General Public License as published
13 * by the Free Software Foundation; either version 2.1 of the License, or
14 * (at your option) any later version.
16 * This library is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
19 * the GNU Lesser General Public License for more details.
21 * You should have received a copy of the GNU Lesser General Public License
22 * along with this library; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
26 #include <linux/slab.h>
27 #include <keys/user-type.h>
28 #include "dns_resolve.h"
30 #include "cifsproto.h"
31 #include "cifs_debug.h"
33 /* Checks if supplied name is IP address
41 struct sockaddr_storage ss;
43 return cifs_convert_address(name, &ss);
47 dns_resolver_instantiate(struct key *key, const void *data,
53 ip = kmalloc(datalen + 1, GFP_KERNEL);
57 memcpy(ip, data, datalen);
60 /* make sure this looks like an address */
66 key->type_data.x[0] = datalen;
67 key->payload.data = ip;
73 dns_resolver_destroy(struct key *key)
75 kfree(key->payload.data);
78 struct key_type key_type_dns_resolver = {
79 .name = "dns_resolver",
80 .def_datalen = sizeof(struct in_addr),
81 .describe = user_describe,
82 .instantiate = dns_resolver_instantiate,
83 .destroy = dns_resolver_destroy,
87 /* Resolves server name to ip address.
91 * *ip_addr - pointer to server ip, caller responcible for freeing it.
95 dns_resolve_server_name_to_ip(const char *unc, char **ip_addr)
98 struct key *rkey = ERR_PTR(-EAGAIN);
103 if (!ip_addr || !unc)
106 /* search for server name delimiter */
109 cFYI(1, "%s: unc is too short: %s", __func__, unc);
113 name = memchr(unc+2, '\\', len);
115 cFYI(1, "%s: probably server name is whole unc: %s",
118 len = (name - unc) - 2/* leading // */;
121 name = kmalloc(len+1, GFP_KERNEL);
126 memcpy(name, unc+2, len);
130 cFYI(1, "%s: it is IP, skipping dns upcall: %s",
136 rkey = request_key(&key_type_dns_resolver, name, "");
138 len = rkey->type_data.x[0];
139 data = rkey->payload.data;
141 cERROR(1, "%s: unable to resolve: %s", __func__, name);
147 *ip_addr = kmalloc(len + 1, GFP_KERNEL);
149 memcpy(*ip_addr, data, len + 1);
151 cFYI(1, "%s: resolved: %s to %s", __func__,